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Bacteria communicate using secreted chemical signaling molecules called autoinducers in a process known as quorum sensing. The quorum-sensing network of the marine bacterium Vibrio harveyi uses three autoinducers, each known to encode distinct ecological information. Yet how cells integrate and interpret the information contained within these three autoinducer signals remains a mystery. Here, we develop a new framework for analyzing signal integration on the basis of information theory and use it to analyze quorum sensing in V. harveyi. We quantify how much the cells can learn about individual autoinducers and explain the experimentally observed input–output relation of the V. harveyi quorum-sensing circuit. Our results suggest that the need to limit interference between input signals places strong constraints on the architecture of bacterial signal-integration networks, and that bacteria probably have evolved active strategies for minimizing this interference. Here, we analyze two such strategies: manipulation of autoinducer production and feedback on receptor number ratios.
Unicellular organisms live in complex and dynamic environments. They sense and respond to both external environmental cues and to each other through quorum sensing, that is, cell-to-cell communication. Adapting to changing environments often requires cells to simultaneously integrate information from multiple environmental inputs, and cells have developed elaborate signaling networks to accomplish this feat. However, the design principles underlying the architectures of these networks remain largely mysterious. For example, in the model quorum-sensing bacterium Vibrio harveyi, three chemical communication signals are integrated to regulate gene expression, but the logic and mechanism underlying this integration are poorly understood. Such open questions highlight the need for new conceptual and theoretical tools to supplement ongoing experimental work. Here, we present a new theoretical framework for understanding signal integration based on information theory (Shannon, 1948) and we use it to study information processing in the V. harveyi quorum-sensing circuit.
Quorum sensing is widespread in the bacterial world and can occur both within and between bacterial species, and even between bacteria and their eukaryotic hosts (Waters and Bassler, 2005). Quorum sensing enables bacteria to alter their behavior depending on the number and/or species of bacteria present and is important for a variety of collective behaviors, such as biofilm formation, bioluminescence, virulence, as well as stress response (Waters and Bassler, 2005, 2006; Bassler and Losick, 2006). The V. harveyi quorum-sensing circuit is among the best characterized of all quorum-sensing networks (Figure 1A). V. harveyi produces and detects three chemical signaling molecules called autoinducers (AIs), AI-1, CAI-1, and AI-2. Although AI-1 is produced only by V. harveyi, CAI-1 is produced by other Vibrio species, and AI-2 is produced by a large variety of both Gram-negative and Gram-positive bacteria and probably functions as a universal signaling molecule. Thus, the use of multiple AIs potentially provides bacteria with information about the local density of V. harveyi, all Vibrio species, and total bacteria (Waters and Bassler, 2005). Sensory information from the three AIs is channeled through a common phosphorelay (see Figure 1). The three autoinducers, AI-1, AI-2, and CAI-1, are detected by cognate transmembrane receptors, LuxN, LuxPQ, and CqsS, respectively (Henke and Bassler, 2004), and they collectively control production of the master quorum-sensing transcriptional regulator LuxR (see Figure 1A; Tu and Bassler, 2007).
As all information about the AIs is channeled through a common phosphorelay, it is unclear how much bacteria can learn about each individual input. Even less clear is how the architecture and kinetic parameters (e.g. kinase and phosphatase rates) of the quorum-sensing network affect its signal-transduction properties. To address these questions, we have developed a new mathematical framework for analyzing signal integration in cells on the basis of information theory (Shannon, 1948; MacKay, 2003). Information theory provides a natural language for formulating questions about information processing and signal integration. It is used extensively in engineering to model signaling in man-made communication devices and has also proven to be a powerful tool in neuroscience (Rieke et al, 1997; Borst and Theunissen, 1999). Very recently, information theory has been applied to genetic networks to study development in fruit fly embryos and to investigate properties of small stochastic biochemical networks (Ziv et al, 2007; Tkacik et al, 2008a, 2008b; Tostevin and ten Wolde, 2009; Walczak et al, 2009). Here, we adapt information theory to study a biological circuit with multiple inputs and a single output.
One of the advantages of using information theory to describe cellular signaling is that, in principle, no detailed knowledge of the components and kinetic parameters that constitute the signaling circuit is required. Rather, the signaling circuit is modeled by its input–output relationship, often called the transfer function, which describes how the output varies as a function of the input signals. The transfer function of the V. harveyi quorum-sensing circuit was recently measured using single-cell fluorescence microscopy (see Figure 1B and Long et al, 2009). In this study, we consider a class of transfer functions for the V. harveyi quorum-sensing circuit on the basis of a simple model of V. harveyi signal transduction consistent with the aforementioned experiments. We show that many features of the experimentally measured transfer function can be understood using information theory. We argue that our analysis of the V. harveyi quorum-sensing network provides insight into broader design principles applicable to many signal integration networks in cells.
A central concept in information theory is mutual information (see below for a mathematical definition). The mutual information is a symmetric measure of the correlation between inputs and outputs, and measures how much one can learn on average about the input from the output, and vice versa. In the context of cellular biology, mutual information provides a measure of how much a cell can learn about external signals. Cells constantly sense their environments and adjust their gene expression accordingly. This requires cells to faithfully convey information about external signals, even in the presence of noise. The mutual information quantifies, in bits, how much bacteria learn about an external signal (e.g. autoinducer). A bit is the standard unit of information and is defined as the quantity of information required to distinguish two mutually exclusive but equally probable states from each other. Consequently, calculating the mutual information between each input signal and the output in a multi-input signaling system, such as the V. harveyi quorum-sensing circuit, allows us to quantify how much bacteria can learn on average about each input from the shared output.
There are three basic components of our information theory formalism: (1) a model of the signaling circuit, (2) a statistical model (a 'prior') for the likelihood of encountering a particular input signal, and (3) the various mutual information between the inputs and the output (Figure 2A). We now discuss each of these components in greater detail.
Mutual information is a statistical quantity that measures the average amount that can be learned about an input, with the average taken over the input prior, q(X, Y). Consequently, all three mutual informations depend on both the transfer function of the signaling circuit, P(ZX, Y) and on the prior, q(X, Y). The relevant expressions are (Shannon, 1948; MacKay, 2003).
with the joint probability p(Z, X, Y)=P(ZX, Y)q(X, Y) and p(Z = ∫ dXdYP(Z|X,Y)q(X,Y), and
with p(Z,X) = ∫ dYP(Z|X,Y)q(X,Y) and p(Z) as above, and the expression for I(Z, Y) is the same as I(Z, X) except with X and Y interchanged I.
Applying information theory to the V. harveyi quorum-sensing circuit requires explicit models for the transfer function and the prior. The input–output relationship for the V. harveyi quorum-sensing circuit was experimentally quantified in genetically engineered strains lacking the CAI-1-CqsS pathway to study the integration of signals from autoinducers AI-1 and AI-2 (Long et al, 2009). In these experiments, strains were engineered with gfp fused to the promoter of qrr4, which is one of the genes encoding the quorum-sensing small RNAs activated by phospho-LuxO. As shown in Figure 1, signals from AI-1 and AI-2 are already integrated at this stage of the quorum-sensing circuit. Recent experimental and theoretical study suggest that the detection of AIs by their cognate receptors (e.g. LuxN, LuxPQ) can be understood using a simple two-state model in which receptors exists in two states: a low kinase activity state ('off') and a high kinase activity state ('on') (Keymer et al, 2006; Swem et al, 2008; Supplementary information). In addition to their kinase activities, the quorum-sensing receptors have a strong state-independent phosphatase activity (Long et al, 2009). AIs act by binding to a receptor and decreasing the probability that the receptor is in the high kinase activity, 'on' state. Thus, specifying the external concentration of an AI in the environment is equivalent to specifying the probability that the corresponding receptor is in its high activity state. Hence, we take the input signals, X and Y, to be the probabilities that LuxN and LuxPQ, respectively, are in their kinase-active states. An advantage of this formulation is that input signals are bounded between 0 and 1. These probabilities are related to the autoinducer concentrations through the formulas
(see Supplementary information).
Motivated by experiment (Long et al, 2009), we model the mean response of the V. harveyi quorum-sensing circuit using the expression
with Z the output signal, that is, the fraction of phospho-LuxO, kX the total kinase rate of active LuxN, kY the total kinase rate of active LuxPQ, and p the total phosphatase rate from both receptors. The second, approximate expression, applies because, for the quorum-sensing circuit, the total phosphatase rate is much larger than the maximal total kinase rate, pkX+kY. The mean transfer function f(X, Y) is plotted in Figure 3 for the cases kXkY, kX=kY, and kXkY. Experiments indicate that the actual kinase activities of the AI-1 and AI-2 pathways are nearly equal (Figure 1B, Long et al, 2009).
In a standard manner, we approximate the probabilistic transfer function, P(ZX, Y) as a Gaussian channel, in which the probability of observing an output for a given input is modeled by a Gaussian distribution around the mean output level for that input (Detwiler et al, 2000; MacKay, 2003; Ziv et al, 2007; Tkacik et al, 2008a, 2008b). Explicitly, we model the noisy transfer function as
where f(X, Y), given by equation (4), is the deterministic transfer function describing the average output Z as a function of the inputs X and Y, and σ(X, Y) is the input-dependent standard deviation of the output signal for a given input (cf. Figure 2B). Experimentally, the standard deviation σ(X, Y) is measured by looking at cell-to-cell variations in a clonal population using single-cell fluorescence microscopy (Long et al, 2009). We expect that (5) is a good approximation for the true transfer function because, experimentally, the noise is well approximated by a Gaussian and is much smaller than the mean signal, σ(X, Y)/f(X, Y)1 (Long et al, 2009).
Unfortunately, little is known at a quantitative level about the natural environment of V. harveyi, making it difficult to accurately model the prior q(X, Y). Therefore, we take the approach of performing all our calculations for a variety of reasonable priors. In this report, we present results for three choices of prior: a flat prior in which all inputs are equally likely, a bimodal prior which is symmetric in the two inputs, and a non-symmetric bimodal prior (see Supplementary information). We have verified that our main conclusions are insensitive to the choice of prior.
Finally, we note that there is a one-to-one correspondence between priors on receptor kinase-active probabilities, (X, Y), and priors on autoinducer concentrations as long as fluctuations in receptor probabilities are negligible. In this case, receptor probabilities and autoinducer concentrations are related by the deterministic equation (3) and any prior on autoinducer concentrations can be transformed into a prior on receptor probabilities. Although the specific form of the transformation of the prior depends on the binding affinities of the autoinducers for the receptors, by definition, the mutual information between the input and output is independent of whether one treats the autoinducer concentrations or the receptor probabilities as the inputs.
In a circuit that integrates multiple signals, information transmission about each individual signal is limited by two distinct phenomena: biochemical noise and interference from other signals (see Figure 2). Noise arises from both the stochastic nature of biochemical reactions underlying the signaling circuit and as well as other sources of cellular variability (Elowitz et al, 2002). In the presence of noise, a single input gives rise to a distribution of outputs. This type of noise limits information transmission because it introduces uncertainty about the input given the output. A second, independent phenomenon that limits information transmission about individual inputs in multi-input circuits is interference from other signals. Generally, different combinations of the input signals can give rise to the same output signal. Consequently, when a multi-input circuit is viewed as a single-input channel for a particular input, other signals introduce additional uncertainty about that input even in the absence of noise, that is, other signals act as additional noise sources (see. Figure 2C).
In the V. harveyi quorum-sensing circuit, experiments indicate that the noise is generally significantly smaller than the mean input signal, with the signal-to-noise ratio always greater than 2.5 (σ(X, Y)/f(X, Y)2.5). Thus, the circuit is always in a 'low-noise' regime. To assess whether noise or interference from other signals is the primary limitation on information transmission about individual signals, we have obtained formulas for the mutual information, I(Z, X) and I(Z, Y), in the low-noise regime using a saddle-point approximation (see Supplementary information). The saddle-point approximation, also known as the method of steepest descent, gives an asymptotic expansion for the mutual information valid in the limit of large signal-to-noise ratio. The mutual information formulas are most easily expressed in terms of transformed coordinates (f, θ) related to (X, Y) by the coordinate transformation (X, Y) → (f=f(X, Y), θ=X). Explicitly one has,
A similar formula can be derived for I(Z, X) (see Supplementary information).
Recall that I(Z, X) and I(Z, Y) measure the average amount of information that can be learned about the individual inputs X and Y from the output Z, and therefore I(Z, X) and I(Z, Y) allow us to quantify information transmission about individual inputs. We find that our approximate expressions for these quantities do not depend on the noise, indicating that information transmission about each input is primarily limited by interference from other signals.
We can also discover how much bacteria can learn on average about all the inputs from the mutual information I(Z,(X, Y)) between the output Z and the ordered pair of inputs (Z, X). In contrast to the case of individual inputs considered above, we find that even in the low-noise regime, total information transmission is limited by noise when both signals are considered. Explicitly, one has
where q(f, θ) indicates the expectation value with respect to the prior distribution
and H(Z) is the entropy of the output Z (see Supplementary information). Notice that I(Z,(X, Y) is primarily limited by the noise, σ(f, θ), in the transfer function. Our approximate expressions are analogous to those obtained for a single-input, single-output biochemical network (Tkacik et al, 2008b; Supplementary information). This follows intuitively because I(Z,(X, Y)) is insensitive to the identity of the individual signals X and Y and thus the circuit effectively has a single input (X, Y) and a single output Z.
We calculated the total information transmission in the V. harveyi quorum-sensing circuit using data from Long et al, 2009 (see Supplementary information). We calculated the mutual information I(GFP, (X, Y)) between the GFP output signal and the inputs, and observed that the information is of order 1.5 bits for a variety of priors. It should be noted that by standard information theoretic inequalities, I(GFP, (X, Y)) is a lower bound on I(Phospho−LuxO, (X, Y)) the information transmitted between the inputs and LuxO, the output of the quorum-sensing phosphorelay (MacKay, 2003). Nonetheless, we stress that I(GFP, (X, Y)) is a reasonable proxy for the true information transmission because information from the inputs is eventually transmitted to the master quorum-sensing regulator LuxR through the small RNAs (see Figure 2A).
Experiments indicate that in V. harveyi, signals from two of the autoinducers, AI-1 and AI-2, are combined strictly additively in a shared phosphorelay pathway, with each autoinducer contributing very nearly equally to the total response (Long et al, 2009). In terms of the mean response (equation (4)), this means that the maximal kinase activities of the AI-1/LuxN and AI-2/LuxPQ pathways are almost identical, that is, kX≈kY. The observed transfer function seems puzzling at first—it is symmetric in the two inputs (see Figure 1B), indicating that bacteria cannot distinguish between AI-1 and AI-2 even though the two AIs encode distinct information about local species composition. This conundrum motivated us to investigate how kinase rates of the two pathways, kX and kY, and phosphatase rate, p, affect information transmission, by calculating the mutual informations, I(Z, X) and I(Z, Y), for different choices of circuit parameters.
Our results indicate that the signal processing properties of the quorum-sensing circuit vary dramatically with changes in the relative strength of the kinase activities of the two pathways. In contrast, when phosphatase activity is large compared with the kinase activity and the noise is small, the net phosphatase activity, p, affects information transmission about individual inputs only modestly. The reason for this is that the phosphatase activity, p, simply rescales the output Z (see equation (4)), and mutual information is insensitive to re-scalings. Figure 4 shows plots of I(Z, X) and I(Z, Y), as functions of the ratio of kinase activities, kY/kX, for various priors. As discussed previously, I(Z, X) and I(Z, Y) are limited primarily by interference between signals, not by noise. Therefore, we used the low-noise expressions (see Supplementary information). Our results indicate that if kY/kX1, I(Z, Y) can be very large (1) but I(Z, X) is very small (1). However, if kY/kX1, I(Z, Y) is very small but I(Z, X) is very large. Thus, if the kinase activity of one pathway is much larger than the other, the cell can only learn about the stronger pathway. Only when the kinase activities of the two pathways are roughly equal, kY≈kX, can the cell learn, in an information theoretic sense, about both inputs. We conclude that V. harveyi must tune kinase activities of AI-1 and AI-2 pathways to be roughly equal to learn about both inputs. Indeed, this is what is observed in experiments (Long et al, 2009). Nonetheless, even when kinase activities are equal, small numerical values of the mutual information (see Figure 4) indicate that interference between signals is a major impediment to learning about individual inputs.
These results can be intuitively understood as follows. The architecture of prokaryotic phosphorelays is such that a single phosphate group is passed from receptors detecting the inputs to the output response regulator. Thus, in the V. harveyi quorum-sensing circuit, all information about the inputs is encoded in a single number, the number of phospho-LuxO molecules. At steady state, bacteria are limited to what is commonly referred to in the language of information theory as 'amplitude encoding', (i.e. all information is stored in the magnitude of the output variable). Amplitude encoding places strong limitations on how signals can be integrated. If the kinase rate of the X-signaling branch is much larger than that of the Y-signaling branch, (kY/kX1), then the number of phospho-LuxO almost entirely reflects the magnitude of the input signal X and contains very little information about Y. However, if (kY/kX1), then the number of phospho-LuxO almost entirely reflects the magnitude of the input signal Y and contains very little information about X. This relation can be observed graphically from the constant output contours of Figure 3. The contours are almost vertical when kY/kX1, indicating that Z is highly correlated with X but largely uncorrelated with Y. The opposite is true when kY/kX1.
We conclude that for the number of phospho-LuxO molecules to contain information about both signaling branches, it is necessary that, on average, both signaling branches phosphorylate about equal numbers of LuxO. In terms of kinase activities, this translates into the requirement that the maximal kinase activities of the two signaling pathways be approximately equal, kX≈kY. In light of these results, we speculate that the reason that the kinase activities of the AI-1/LuxN and AI-2/LuxPQ pathways are nearly identical is to allow bacteria to learn about the concentration of both autoinducers individually.
Setting kX≈kY has the consequence of introducing symmetry in the input–output relation such that bacteria cannot distinguish the input (X, Y) from the input (Y, X). For example, bacteria cannot distinguish saturating AI-1 and no AI-2 condition from saturating AI-2 and no AI-1 condition (Long et al, 2009). This constraint limits how much cells can learn about either input. Quantitatively, from our calculations, for kX≈kY, cells can learn only about 0.6–0.8 bits about each input signal, with the exact number depending on the choice of prior. This is significantly less information than that contained in the input distribution. For comparison, bacteria would have to learn 1 bit to distinguish between two states of the autoinducers (e.g. high and low concentration) and the Bicoid–Hunchback system in early Drosophila development was recently measured to transmit 1.5 bits (Tkacik et al, 2008a). The low mutual information between inputs and outputs indicates that interference between signals greatly limits information transmission in these systems and serves as a major impediment to learning about multiple signals. This observation led us to consider possible mechanisms that would allow bacteria to increase how much they learned about individual inputs. Below, we consider two such strategies: manipulation of individual input signals and feedbacks on receptors.
In quorum sensing, bacteria both produce and detect autoinducers. This led us to consider whether bacteria could increase the information they obtain about their environments by manipulating relative autoinducer production rates. As discussed, the primary limit on information transmission when the kinase rates of AI-1 and AI-2 signaling pathways are equal is the symmetry in the input–output relation. We hypothesized that bacteria may distinctly manipulate the different autoinducer production rates to remove the ambiguity between the two input signals, and thereby increase the information the AIs provide. For example, bacteria could temporally segregate signals by first producing one autoinducer and then the other. Alternatively, V. harveyi could produce AI-1 and AI-2 at the same rate. This solution would ensure that there was always more AI-2 than AI-1 in the environment because AI-1 is produced only by V. harveyi, whereas AI-2 is produced by almost all bacteria. Within our model, this arrangement corresponds to limiting the input signaling space to XY. We calculated I(Z, X) and I(Z, Y) for the latter scenario and the results are shown in Figure 4. We found that when kX≈kY and XY bacteria could learn ≈1.5 bits about each signal, double of what they can learn when the input space is unrestricted. The additional information gained by the cell stems from the elimination of the degeneracy between AI-1 and AI-2. Namely, for intermediate levels of output, bacteria now know that there is high amount of AI-1 and low amounts of AI-2 in the environment and not high AI-2 and low AI-1. This result confirms that in principle, bacteria can increase information transmission by manipulating autoinducer production rates.
The information theory analysis presented above shows that the signaling properties of the V. harveyi quorum-sensing circuit are sensitive to changes in the kinase rates of the inputs. This raises the intriguing possibility that bacteria might implement more sophisticated signal detection strategies by varying kinase activities as a function of inputs. A simple architecture for achieving this goal would be a feedback on receptor number. Indeed, preliminary experiments indicate such a feedback may exist in the quorum-sensing circuit of V. harveyi, with sRNAs negatively regulating production of LuxN (L Schaffer and B Bassler, unpublished data). We show below that such feedbacks on receptor number potentially allow bacteria to 'focus attention' on different inputs depending on their external environments.
The maximal kinase activity of each autoinducer pathway in V. harveyi depends on two separate quantities: (1) the total number of receptors, and (2) the maximal kinase activity of each individual receptor. Explicitly, maximal kinase rates of the X (AI-1) and Y (AI-2) pathways obey kX=kX0NX and kY=kY0NY, with NX and NY the number of receptors in the X and Y pathways, respectively, and kX0 and kY0 the maximal kinase activities of the individual receptors. Thus, in principle, bacteria can modulate the ratio of maximal kinase rates between the two pathways, kY/kX, as a function of the output, Z, through feedback on receptor number (see Figure 5 and Supplementary information).
We consider here two simple feedback architectures: (1) positive feedback on NY and (2) negative feedback on NX (see Figure 5). In the main text, we restrict our discussion to the case of positive feedback, assumed to act on the receptors in the Y pathway. We consider a positive feedback on the receptors in the Y pathway. In this case, the transfer function, Z=ffb(X, Y), describing the output signal (the fraction of phosphorylated output regulators), as a function of the inputs X and Y (the probability that the corresponding receptors are in their on states) is obtained by solving for the steady state of the differential equations
where NY0 is the number of receptors in the absence of feedback, δNY measures the strength of the feedback, K is value of Z, which is half-maximal for the feedback. When δNyNY0, this implies that at high Z, δNYNY0. For simplicity, we have assumed a Hill coefficient of 1 for the feedback and that the phosphatase rate is independent of the receptor number. We also assume, as above, that the phosphatase rate is much larger than the maximal kinase rate pkX, kY for all choices of inputs. We obtain the steady-state solution by setting the left hand sides of the above equations to zero, which yields
where, for simplicity, we denote the steady-state output by Z. This equation can be solved for Z to obtain the transfer function, ffb(X, Y), in the presence of feedback.
A particularly interesting parameter range is the regime when kY0(NY0+δNY)kXkY0NY0. In this case, the maximal kinase activity of the X-pathway is much greater than the maximal kinase activity of the Y-pathway at low Z, and the opposite is true at large Z. Thus, the positive feedback on receptor number, NY, allows the bacteria to access information preferentially about input X at low Z (i.e. at high cell density) and learn preferentially about Y at high Z (i.e. at low cell density). In the low-noise limit, the mutual informations, I(Z, X) and I(Z, Y), only depend on three combinations of parameters, ratios of the maximal kinase activities in the presence and absence of feedback, and the half-maximal value of the feedback K (data not shown). Thus, by rescaling X and Y, we can consider the equivalent transfer function
with C=kY0NY0/kX, δC=kY0δNY/kX.
Both of these feedback architectures allow bacteria to tune kinase rates of the two pathways so that kY/kX1 at large (X, Y) and kY/kX1 at small (X, Y). This can be understood graphically in Figure 5A that shows contour lines of constant output, Z, for different values of the inputs X and Y in the presence of a positive feedback from Z on NY. It is noteworthy that for X and Y near 1 (i.e. at low cell density), the constant-Z contours are more horizontal indicating that kY/kX1, whereas for X and Y close to zero (i.e. high cell density), the contour lines are much more vertical indicating that kY/kX1. Therefore, for the positive feedback shown in Figure 5, bacteria preferentially learn about Y (AI-2) at low cell densities and about X (AI-1) at high cell densities. Though less pronounced, analogous results can be achieved using a negative feedback on NX (see Supplementary information).
To quantify information transmission for such feedback architectures, we calculated the mutual informations, I(Z, X) and I(Z, Y), in the presence of feedbacks for various choices of kinetic parameters and a flat prior (see Supplementary information). In all our calculations, we assumed the signal-to-noise ratio to be large, σ(X, Y)/f(X, Y)1, and used the low-noise expressions derived in the Supplementary information. In this limit, I(Z, X) and I(Z, Y) are limited primarily by interference between signals and are independent of any specific choice of noise, σ(X, Y). We found that mutual informations in the presence of either a positive feedback on the receptors for input Y or a negative feedback on the receptors for input X are comparable to those in the absence of feedback. This finding indicates that bacteria can preferentially detect AI-2 (X) at low cell densities and AI-1 (X) at high cell densities without sacrificing how much they learn on average about both inputs. For example, for both the feedback transfer functions shown in Figure 5, I(Z, X) and I(Z, Y) are both ≈1.5 bits for the case when XY, comparable with their values in the absence of feedback (see Figure 4).
Cells constantly sense their environments and adjust their behavior accordingly. Specifically, cells often integrate temporally coincident information from multiple environmental inputs to modulate their gene expression states. However, mechanisms and logic by which cells integrate multiple signals remain by and large poorly understood. We developed a new, mathematical framework for analyzing information processing in cells based on information theory, and used it to study the integration of multiple autoinducer signals using the model quorum-sensing bacterium Vibrio harveyi. Our studies revealed that there are two distinct mechanisms that limit information transmission when bacteria integrate multiple signals, biochemical noise and interference between different signals. Although the former limits the total information that bacteria can learn about all the inputs, signal interference is the primary impediment to learning about individual input signals. Furthermore, we showed that because of signal interference, V. harveyi cells must precisely tune the kinase activity of each input branch of the quorum-sensing pathway to simultaneously learn about individual autoinducer inputs. These theoretically motivated conclusions are consistent with recent quantitative experiments on V. harveyi showing that the maximal kinase activities of AI-1 (LuxN) and AI-2 (LuxPQ) pathways are nearly equal (Long et al, 2009). Our information theory analysis also indicates that bacteria can increase how much they learn about individual inputs by manipulating the different autoinducer production rates. Finally, we have shown that bacteria can learn preferentially about a particular signal in a particular environment, even with a single-output pathway, by using simple feedback loops to control receptor numbers.
Our theory not only explains the puzzling experimental observation of nearly equal kinase activities of the LuxN and LuxPQ pathways (Long et al, 2009), but also makes several testable predictions about the V. harveyi quorum-sensing circuit. First, we predict that the maximal kinase activity of the CAI-1/CqsS branch, when measured, will prove to be similar to that of the AI-1/LuxN and AI-2/LuxPQ pathways (see Figure 2). This prediction follows directly from our information theory analysis, which indicates that the three signaling branches must phosphorylate about equal numbers of LuxO for cells to simultaneously learn about all three input signals. Second, the theoretical work presented here suggests that V. harveyi may manipulate both autoinducer production and receptor numbers to reduce interference between signals, and thereby increase information transmission. Preliminary evidence suggests that this is the case.
An as yet unanswered question is why V. harveyi and related species use multiple autoinducers (AIs) and then funnel all the information from these autoinducers into a single-output pathway. We speculate that different concentrations of multiple autoinducers may represent different stages of community development such as the stages of growth in a biofilm. Unlike eukaryotic development, for example, embryogenesis, in which the rate of development is fixed and driven by a clock (Nieuwkoop and Faber, 1994) and the input signal is often stereotyped (Gregor et al, 2007a, 2007b), the rate of development of a bacterial community depends on unpredictable environmental conditions, such as nutrient availability and population composition and density. To compensate for such variability, quorum sensing could allow bacteria to monitor stages of community development and act accordingly. The architecture of the V. harveyi quorum-sensing circuit, with multiple inputs and a single output, is consistent with the idea that V. harveyi uses quorum sensing to implement a single, multi-stage developmental program, with different genes activated at different levels of LuxR expression. Indeed, Long et al (2009) showed that V. harveyi can 'count' the number of autoinducer signals present. Thus, if AIs accumulate in a defined sequential order, the number of autoinducers present at saturating concentration could signal different stages of development. For example, models of biofilm growth suggest that the universal autoinducer AI-2 may be more informative at early stages of biofilm growth in which communities are expected to be mixed, whereas the species specific autoinducer AI-1 may be more informative at later stages when mostly progeny are nearby (Nadell et al, 2008).
Our detailed analysis of the V. harveyi quorum-sensing network has implications for other prokaryotic signal-integration networks. Signal integration is a common feature of many organisms, and bacteria have developed sophisticated molecular mechanisms for integrating signals from a broad range of inputs using two-component systems and phosphorelays (Perego, 1998; Bassler and Losick, 2006; Kato et al, 2007; Mitrophanov and Groisman, 2008). For example, the sporulation and competence circuits of the soil-dwelling bacterium Bacillus subtilis integrate signals from the environment, cell cycle, and metabolism using a network design based on competition between various protein kinases and phosphatases (Perego, 1998; Veening et al, 2008). Our information theory analysis suggests that the need to minimize interference between signals probably places strong constraints on the design of such signal-integration networks. In particular, our work indicates that the information transmission properties are likely to be extremely sensitive to changes in kinase and phosphatase rates, and that bacteria may have evolved strategies for minimizing interference. One possible strategy for learning about individual input signals is to temporally coordinate signals (Mitrophanov and Groisman, 2008). For example, recent experiments on the B. subtilis sporulation and competence networks indicate that bacteria probably temporally separate input signals (Smits et al, 2007; Veening et al, 2008).
Bacteria may use a range of mechanisms to minimize signal interference by actively controlling both signal production and detection. A simple way to achieve such control is through feedbacks on synthases/receptors. For example, feedbacks on AI production are a common feature of many quorum-sensing systems (Waters and Bassler, 2005), suggesting bacteria actively manipulate the temporal profile of AI production. In V. harveyi, recent experimental evidence suggests such a feedback may act on the AI-1 synthase LuxM (L Schaffer and B Bassler, unpublished data). Moreover, the gene encoding LuxM is located in an operon with the gene encoding the AI-1 receptor LuxN, indicating the feedback also acts on receptor numbers, potentially allowing V. harveyi to focus on different autoinducers at different stages of development. Recent experiments also indicate that Escherichia coli cells manipulate chemoreceptor numbers using feedbacks. When starving, E. coli cells change the ratio of Tar to Tsr receptors, resulting in a change of behavior from heat seeking to cold seeking (Salman and Libchaber, 2007).
The use of signaling pathways with multiple inputs and a single output necessarily entails a loss of information about input signals. This raises the natural question of why such pathways are used by bacteria. For example, one can imagine alternative architectures in which each input is detected by a dedicated signaling pathway and information about multiple inputs is integrated at the promoters of regulated genes through combinatorial gene regulation (Kato et al, 2007; Mitrophanov and Groisman, 2008). We have argued that for V. harveyi such a multi-input, single-output architecture facilitates the implementation of a linear, multi-stage, developmental program. The architecture of signal integration networks may also reflect evolutionary constraints. For example, such networks may have evolved from a single pathway by gene duplication. In addition, when the output of a signal integration network is a master transcription factor regulating the expression of many genes (e.g. LuxR in V. harveyi), the use of a single-output pathway may be more efficient with regard to use of space on the genome than a competing architectures consisting of individual signaling pathways, one for each input, culminating in combinatorial gene regulation. Recent experiments indicate that the sporulation network in B. subtilis may have a similar role in regulating biofilm formation (Vlamakis et al, 2008). In light of the accumulating evidence that bacterial populations behave similarly as multicellular organisms (Shapiro, 1998), we suspect that the use signal integration networks to coordinate development programs may be widespread in prokaryotes.
The study presented here focuses on signal integration in bacteria. The architecture of prokaryotic phosphorelays, in which a single phosphate group is transferred sequentially to downstream components, constrains bacteria to encode information using amplitude encoding, that is, all information about input signals is contained in the number of active response regulator molecules. The use of amplitude encoding places strong constraints on network architecture and limits the amount of information that bacteria can transmit. This contrasts with neural networks, in which spike timing allows neurons to encode information using more sophisticated schemes (Rieke et al, 1997). Signaling in bacteria also differs from signaling in eukaryotes, which often uses multiple phosphorylation sites and kinase cascades that permit temporal encoding schemes, such as dose–duration encoding (Detwiler et al, 2000; Behar et al, 2008). It may prove fruitful to generalize our information theoretic formalism to these more complicated intracellular circuits.
Finally, our results suggest that information theory may prove to be a powerful general tool for analyzing biological signaling networks. Information theory provides a natural language for formulating questions about information processing and signaling integration. An additional advantage of an information theoretic analysis is that no detailed knowledge of the signaling circuit is required. All quantities are calculated using the input–output relationship of a signaling circuit, often an experimentally accessible quantity, even for large signaling networks. For these reasons, we expect the application of information theory to yield new biological insights into cellular signaling in the future.
Supplementary Information, Supplementary figures S1–3
We would like to thank Thierry Mora, Anirvan Senputa, the Wingreen and Bassler labs, and the Princeton biophysics theory group for useful discussions. This study was supported by US National Institute of Health (NIH) grant K25 GM086909-01 (PM); partially supported by the Burroughs Wellcome Fund Graduate Training Program (SG and TL); partially supported by the Defense Advanced Research Projects Agency (DARPA) under grant HR0011-05-1-0057 (SG and NW). This work was also partially supported by National Science Foundation (NSF) Grant Phys-0650617.
The authors declare that they have no conflict of interest.
PubMed Central Canada is a service of the Canadian Institutes of Health Research (CIHR) working in partnership with the National Research Council's national science library in cooperation with the National Center for Biotechnology Information at the U.S. National Library of Medicine(NCBI/NLM). It includes content provided to the PubMed Central International archive by participating publishers.


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Sukh Sagar Apartment, Flat No 8A&B 8th Floor Kolkata West Bengal 700 020
KALIGHAT Kolkata West Bengal 700026
Flr-2 KOLKATA G P O Kolkata West Bengal 700001
3rd Flr KOLKATA G P O Kolkata West Bengal 700001
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I found these hair chalks in the "impulse buy" section of my local Rite Aid. (By "impulse buy" section, I am referring to literally the entire makeup department.) I immediately thought, "Wow this is a really practical buy. Otherwise, what will I do if I suddenly find out that I need blue and/or green hair?" Then, of course, I gave myself a frugal high-five for purchasing a mere two colors, instead of all six-or-so that they had on display. I purchased "Slimy Lime", which is Crayola Green, and "Cryptic Blue", which is a primary-color blue. They are both simple, bright colors... the kind of colors that wouldn't confuse preschoolers. ("What color is this, Billy?" "Pink?" "STAY IN SCHOOL, BILLY, IT'S A WARM-TONED FUSCHIA.")
I have good news and I have bad news.
The bad news is that these are kind of shitty hair chalk. I found that I had a very difficult time building up any color. Furthermore, even setting it with hairspray didn't prevent massive amounts of fading. I can tell it stayed in my hair because when I showered at the end of the night, it turned my bathtub the color of a polluted lagoon. However, it kind of hung out incognito; by lunchtime, you couldn't really see the color at all.
I also discovered that I had to use an absurd amount of chalk. My hair (pictured below) took about half of each of those chalk containers and it is still subdued enough to appear half-hearted.
The good news is that these chalks do have one super handy purpose: eyebrow colors! It's hard to find a good drugstore eyebrow color and, for me, eyeshadow usually doesn't cut the mustard. They got a little powder-y when used for brows, but the color payoff is good and the price is right.
|Fright Night Hair Chalk in Slimy Lime on Human Eyebrows
|Fright Night Hair Chalk in Cryptic Blue on Human Eyebrows


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You missed it This great deal for Evergreen Laser is over. But don't despair, we've got more great deals every day.
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Steve Harvey on Oscars gaffe: 'I'm free at last!'
LOS ANGELES — If Warren Beatty needs someone to talk to following Sunday night's epic award mix-up at Sunday night's Oscars, Steve Harvey is open ears.
Bowie lawyers searching for secret love children
Lawyers for late rock icon David Bowie have asked any secret heirs who might lay claim to his US$100 million fortune to come forward.
U.K.'s tallest man, 'Game of Thrones' actor dies
LONDON — Neil Fingleton, a 7-foot 7-inch actor who played the giant Mag the Mighty in "Game of Thrones" has died at 36.
Celebs, fans mourn Bill Paxton
Hollywood star Bill Paxton has died after suffering complications from surgery.
Lovato sorry for '1% African' tweet
Demi Lovato apologized on Friday for sharing the results of a DNA test which revealed she is one per cent African.
Willie, Whoopi launch pot brands
Country singer Willie Nelson, the children of the late reggae icon Bob Marley and comedian Whoopi Goldberg are just a few of the growing number of celebrities publicly jumping into the marijuana industry and eyeing the California pot market, which is expected to explode after voters legalized the recreational use of weed.
John Legend's Twitter account hacked
John Legend has poked fun at the hacker who took over his Twitter account.
Derringer pleads guilty to carrying gun on plane
Rock guitarist Rick Derringer has pleaded guilty and agreed to pay a US$1,000 fine after stepping off a Delta Air Lines flight from Mexico with a loaded handgun in Atlanta's airport.
Amal Clooney shows off baby bump
George Clooney's pregnant wife Amal glowed on the red carpet at the Cesar Awards in France on Friday as she debuted her baby bump in public.
Bieber swears he didn't actually pee his pants
Justin Bieber has assured fans he didn't soil himself after he was pictured with a wet patch on his trousers on Wednesday.
Patton accuses Thicke of evidence tampering
Robin Thicke's ex-wife is accusing the singer of tampering with a court order in an attempt to get her arrested in their bitter custody dispute.
'Family Matters' star claims wife attacked him
Former Family Matters star Darius McCrary has won a restraining order against his wife after she allegedly attacked him with an iron.
Game of Thrones' star spotted in Calgary
Maisie Williams, a.k.a. Arya Stark, has been spotted in Calgary and Banff over the last couple of days, apparently taking a break from shooting scenes with Alberta wolves for the seventh season of Game of Thrones.
Brady jokes about possible jersey thief suspects
Super Bowl-winning quarterback Tom Brady has jokingly named Lady Gaga among the possible culprits suspected of stealing his jersey after the big game.
O'Connor apologizes for Hall drug claims
Comedian Arsenio Hall has agreed to drop his US$5 million defamation lawsuit against Sinead O'Connor after she apologized for accusing him of providing drugs to Prince.
Video shows Harrison Ford flying over airliner
SANTA ANA, Calif. — Video released Tuesday shows a plane piloted by Harrison Ford suddenly and mistakenly flying low over an airliner with 110 people aboard at a Southern California airport.
Jamie Foxx target of alleged racial slur
Croatian police have filed disorderly conduct charges against two people who allegedly used a racial slur to insult Hollywood actor Jamie Foxx in a restaurant.
Amber Tamblyn and David Cross welcome baby girl
Actress Amber Tamblyn and her comedian husband David Cross have become parents for the first time.
Chris Brown and Soulja Boy fight called off
The boxing match between Chris Brown and Soulja Boy has been called off.


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This is a very new and modern hotel. The installations are very good considering the place you are at. I went twice to this hotel in march and the rooms where clean and comfortable (they where suites). Cons: No room service or any kind of food and beverages after 11 even do the night flight from Lima commonly arrives after midnight. The complementary breakfast was also very poor, but the restaurant for lunch and dinner has a very decent menu and tasty meals. The staff is also very friendly and willing to help you anyway they can. Shuttle service to the airport also works great. To me even do the cons is the best or only decent choice in Pucallpa.
- Also Known As:
- Ucayali River Hotel Pucallpa, Peru


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I can only guess that the person who invited the OP has a completely bogan red-neck family with no clue whatsoever about what's considered appropriate for a christening. It's just too bizarre!! If I held a christening I'd just be happy that anyone turned up!!
It's so varied. Smart casual to me means a nice pair of jeans, nice shoes and nice top and swish handbag and that I would wear to a christening.
GirlsRock (03-01-2016)
nothing too plunging or booby for church either. that first maxi is stunning (in the pics posted above) but I'd feel a bit "on show" wearing it to church.
Thank you ladies for your responses. It has seriously confused me....I actually asked the person earlier who requested the "dress code" what they would want me to wear and not to wear.
Black is bad apparently....my wardrobe consists of mostly black.
Now I'm not a big spender on clothing....I'm quiet plain and just shop at tempt or valley girl. So once I get my answer I'll go and look for something.
(Please don't judge on where I shop) they have nice clothes.
Seriously just wear what the hell you want, even black. Just watch there will be quite a few ppl in black.
Oh I've been in your situation before with people telling me specifically what I can and can't wear, it's so annoying!
I really feel for you. If it's causing you stress don't be afraid to just rsvp no. I've done that before when I was told I couldn't wear anything I own and I should buy something new. Like you I'm not really into clothes and I don't see the point in buying something to only wear once. If people really want your company they won't care what you wear.
Jontu (03-01-2016),LoveLivesHere (03-01-2016)
Can I just ask what you would wear to dinner with friends? Just wear that tbh. Even if there is black in the outfit it would not be a big deal. If shopping especially for something is stressing you out - then don't worry about it and go with what you have.
OP, find something comfy that you will wear again, team it with nice sandals and you will be fine.
lilypily (03-01-2016)
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December 27th, 2015
Residents of Quebec can enter here for a chance to win a Amarula DAVIDsTEA prize pack. I hope that mug is part of the prize. I don't have one like that. I drink my tea from a Pac-Man mug. Good Luck!
Entry Frequency: single
Open to: QC
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alexandriava22301 Review
Great bed!
This is a great bed! As mentioned below, the drawers are very roomy -- it probably provides as much storage as two large dressers. It's very solid and sturdy. The fabric is nice too -- we got the charcoal color and it looks just as advertised on the site. Looks great in our gray and white bedroom. We had a minor issue with delivery (the delivery guy didn't think that the "white glove delivery" included putting the bed together). I called overstock to clarify and they fixed it right away -- they had the company come back that afternoon and put it together. All in all a great bed and very good customer service.
- How did the color on site compare with the actual product? Exact match
- Please tell us about the quality of the product. Very good
- How accurate was the on site description of the product? accurate
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So living in a large rural city in the middle of Victoria's food bowl last year, I was fully expecting the mice plague to eventually invade my home. Thankfully, they never did.
But we moved a month ago, to a town right on the Murray River. It's literally 500m from my front door. And we have mice!
It's a brand new house, and I clean it thoroughly every Saturday morning (just finished!) as well as tidying as I go through the week. So.. I don't think they're here because we're dirty because we're really not!
As well as the mice, the incredible amount of flies is annoying me too! (You would think that growing up in this town I would be used to it, but living away for 6 years I guess I became accustomed to pest-free environment!)
I just looked at research on the ultrasonic plug in devices, but science says they can be nothing but a dud, since the pests habituate to the sound, it doesn't annoy them anyway, and besides- ultrasonic sound cannot go around corners or through walls or furniture, and it loses half it's strength after 15ft and is gone after 30ft.
DP went to Bunnings a few weeks ago and bought some self-baited traps which were supposed to be irresistable to mice, but so far they remain empty, whilst I see mice run into the garage and my linen cupboard (gross )
So- any tips on pest control?


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- Posted Feb. 20, 2012 by David Swatton in Flora & Fauna. Viewed 2098 times
- This is a migrated legacy post. Image resolution is low. Info
In the hothouse at Wisley they currently have hundreds of butterlies fluttering by so we went along there yesterday… with what seemed like about a million other people!
12 There are 12 comments, add yours!
2012.03.05 Edited
Fantastic set, the first shot goes straight into my fav.list!
2012.02.23 Edited
Always fun to chase butterflies around in a confined space... too much trouble when they can get away!
2012.02.21 Edited
love the first one
2012.02.20 Edited
love #1
2012.02.20 Edited
bellissime. come tutte le tue fotografie . baci
2012.02.20 Edited
Very exotic!
2012.02.20 Edited
These are so beautiful. I didn't get to see them when I visited last week as the queue was over an hour to get in. I think your shots have persuaded me to go back on Friday without the half term crowds!
2012.02.20 Edited
These are gorgeous photos. Especially the first. I have always agreed that flutterbies would make much more sense for a name.
2012.02.20 Edited
these are beautifull!very nice shapes and colors.
2012.02.20 Edited
one of the things I never get to take a decent shot of,,, they seem to be an impossible mission to me :) that blue one in 1 is spectacular!
2012.02.20 Edited
The canvas of a butterfly's wings will always make my heart flutter!
2012.02.20 Edited
What a great place to go on a cold winters day... you managed to capture some real beauties!


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Hotfrog NewZealand provides information regarding Home in Palmerston North. Home is located at PO Box 1700, Palmerston North 4440 and provides Air Conditioning services. Contact them on 021 173 3234 or by visiting them on their website http://www.nacs.co.nz.
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When your challenge is to convince a (prospective) client of the value of your IT consultancy, you have to be prepared to convince them from the kickoff meeting. That's where the impact of experiential learning through Business Simulations and Serious Games is a real gamechanger for your client and a differentiator for your company. Experiencing your consultancy's approach firsthand, seeing you in action, is persuasive. And Business Simulations help you understand your client, assess their business needs and organizational culture, and 'speak the same language' crucial to building trust and confidence.
Business Simulations can provide a competitive advantage and bring leadership to your market promising new business opportunities. See how Simagine Business Simulations answer The 5 Must-Have Elements for Powerful Business Simulations.
Simagine Business Simulations are authentic, engaging and 100% relevant for any organization looking at change or process improvement. With a flexible approach and no fixed scenarios, you will benefit from incorporating an innovative and effective learning solutions for your practice. You will be able to offer your clients more effective solutions for business IT alignment, end to end business processes optimizations, IT service management and IT architecture improvement.
Support the Adoption of DevOps with the Business Simulation Bridge-it: Change the mindset of your clients' development and operations team(s).
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A Heart Effort is a very effective game to complete your offering or to serve as a starting point for a change program. Participants highly enjoy playing the game, sharing opinions, hearing new viewpoints. Well embedded in a positive atmosphere minds are opened to new decision making.Sandra Kruijt, Owner and Director at Priorities-Professional Organizing
I've been using Control IT for more than 12 years now. I must have 'played' it with different groups more than 200 times. It's simply great! It gives you the possibility to quickly show your audience where they could improve by just applying basic rules.Peter Gerritsen, Owner and Director at Pepper Group
Flexibility is key when identifying a client's need or business problem. The Simagine sessions demonstrated it has the ability to be a stand-alone session, integrated into a Certification course (ie. ITIL Foundation), or may be included as a tool in a Consultant's toolbox.Consultant at CASK, USA
ITpreneurs provides IT training content, Instructors, Learning Infrastructure and services to training providers, offering these training providers a whole new way to run their business: high impact, low barrier. With thousands of titles covering all key domains within IT, training providers can easily broaden their portfolio and create new revenue without needing to invest in in-house content development and maintenance. Content for training programs is available in up to 15 languages.
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Simagine develops Business Simulations which are not only flexible but are also relevant and realistic. Thanks to the three key concepts, the Simulations have an effect on the learning and change situation in question. The Business Simulations are flexible enough that they can even be adapted to the participant group while being enacted. They are relevant enough for specific subjects in a recognizable organizational environment. And they are realistic, so that participants can make the transfer from the Business Simulation to their daily reality. Learn more about Simagine at simagine-international.com.


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"Murphy was an optimist!"
Men can die December 2, 2005 10:06 amPosted by djuggler in : Daily Life
University of Pennsylvania managed to grow mouse "spermatagonial stem cells" in a dish
That's the stuff that becomes sperm. And the neat thing is they've learned how to alter the genes such that the alterations are passed from generation to generation. In other words now that men aren't necessary (and they really haven't been since the invention of the massager), you can guarantee that all offspring are female!
On a side note, treatment for hysteria was first recommended in 1653.
no comments yet - be the first?


text:
|Publication number
|Publication type
|Application number
|Publication date
|Mar 31, 1987
|Filing date
|Jul 12, 1985
|Priority date
|Jul 16, 1984
|Fee status
|Also published as
|Publication number
|Shinji Kojima, Hirokazu Suzuki, Yuichi Orikasa
|Original Assignee
|Nippon Petrochemicals
|Export Citation
|BiBTeX, EndNote, RefMan
|Patent Citations (2), Referenced by (31), Classifications (66), Legal Events (6)
|External Links: USPTO, USPTO Assignment, Espacenet
1. Field of the Invention
This invention relates to adhesive resins which have good adhesion to various other materials such as polyolefins, polyamides, polyesters, saponified ethylenevinyl acetate copolymers and metals, and also to laminates using the same. More particularly, the invention relates to adhesive resins which are obtained by chemically combining 0.01-10 parts by weight of ethylenically unsaturated fatty acids or derivatives thereof with 100 parts by weight of epoxy group-containing olefin polymers, and to laminates using such adhesive resins. The laminates are useful as food wrap films or materials for food containers.
2. Description of the Prior Art
There have heretofore been proposed and used various types of laminate products which are made by laminating such materials as polyolefins, polyamides, polyesters, saponified ethylene-vinyl acetate copolymers or metals with different kinds of materials so that one material compensates for the defect of another. For instance, laminates of polyolefins with polyamides or polyesters are known as good wrap materials. Because of their good transparency, flexibility, hygienic properties and heat sealability, polyolefins have been wisely used as wrapping or packaging materials for foods. However, polyolefins have a shortcoming in that owing to their high permeability to gases such as oxygen, carbon dioxide and the like, they are unable to preserve foods over a long term. On the other hand, although polyamides have good resistance to heat and an oil, they are poor in vapor permeability and heat sealability. Polyesters or saponified ethylene-vinyl acetate copolymers have low gas permeability and good heat resistance, but they are disadvantageously poor in heat sealability. These disadvantages can be overcome by lamination of polyolefins and these other materials.
However, lamination of these materials involves the drawback that adhesion between these materials is poor, causing delamination or ply separation to readily occur.
There have been conventionally proposed, as adhesive resins capable of improving the interlaminar bond strength, ethylene-vinyl acetate copolymers, ionomer resins or polyolefin resins modified with maleic anhydride or the like (see, for example, Japanese Laid-open Patent Application Nos. 51-92880, 52-32080, 54-82, 54-87753 and 54-160481). However, these resins have good compatibility with polyolefins or polyamides and a fairly high interlaminar bond strength, but are not yet satisfactory. In addition, the strength of adhesion to polyesters is not so high as to stand practical use.
It is accordingly an object of the present invention to provide adhesive resins which overcome the drawbacks of the prior art resins.
It is another object of the invention to provide adhesive resins which have improved interlaminar bond strength with respect to polyolefin and polyamide resins and have much improved adhesion to certain types of low-adhesive resins like polyesters and saponified ethylene-vinyl acetate copolymers.
It is a further object of the invention to provide various types of laminates using the adhesive resins of the type mentioned above whereby high interlaminar bond strength is ensured.
According to one embodiment of the invention, there is provided an adhesive resin which is obtained by reacting 100 parts by weight of an epoxy group-containing olefin polymer with 0.01-10 parts by weight of an ethylenically unsaturated fatty acid or derivative thereof.
According to another embodiment of the invention, there is also provided a laminated article which comprises at least two layers. One layer consists of an adhesive resin which is obtained by reacting 100 parts by weight of an epoxy group-containing olefin polymer with 0.01-10 parts by weight of at least one ethylenically unsaturated fatty acid or derivative thereof, or an olefin polymer composition comprising the adhesive resin. The other layer may be of a material selected from thermoplastic resins, thermosetting resins, rubbers, metals, cloth, paper, wood or glass.
The epoxy group-containing olefin polymers used in the present invention may be copolymers of olefins and unsaturated glycidyl group-containing monomers, and terpolymers or multi-polymers of olefins, unsaturated glycidyl group-containing monomers and ethylenically unsaturated monomers. The olefins in the copolymers should preferably be ethylene. Preferable copolymers consist of 50-99.96 wt % of ethylene, 0.05-50 wt % of a glycidyl group-containing monomer, and 0-49.95 wt % of an ethylenically unsaturated monomer.
Examples of the unsaturated glycidyl group-containing monomers include glycidyl esters such as glycidyl acrylate, glycidyl methacrylate, monoglycidyl itaconate, monoglycidyl butenetricarboxylate, diglycidyl butenetricarboxylate, triglycidyl butenetricarboxylate, glycidyl esters of alpha-chloroallyl, maleic acid, crotonic acid, fumaric acid and the like, glycidyl esters such as vinyl glycidyl ether, allyl glycidyl ether, 2-methylallyl glycidyl ether, glycidyloxyethyl vinyl ether, styrene-p-glycidyl ether and the like, and p-glycidylstyrene. Preferably, glycidyl methacrylate and acryl glycidyl ether are mentioned.
The ethylenically unsaturated monomers of the invention may be at least one monomer selected from olefins, vinyl esters, alpha, beta-ethylenically unsaturated carboxylic acids and derivatives thereof. Specific examples include olefins such as propylene, butene-1, hexene-1, decene-1, octene-1, styrene and the like, vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate and the like, acrylic acid, methacrylic acid and esters thereof such as methyl, ethyl, propyl, butyl, 2-ethylhexyl, cyclohexyl, dodecyl, octadecyl, acrylates or methacrylates, maleic acid, maleic anhydride, itaconic acid, fumaric acid, maleic mono and diesters, vinyl chloride, vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and the like, and acrylic amides. Of these, acrylates are preferred.
The epoxy group-containing olefin polymers are prepared according to a high pressure radical polymerization process in which 50-99.95 wt % of ethylene, 0.05-50 wt % of at least one unsaturated glycidyl group-containing monomer, and 0-49.95 wt % of at least one other ethylenically unsaturated monomer are contacted simultaneously or in a stepwise manner for polymerization in a vessel or tubular reactor in the presence of 0.0001-1 wt % of a free radical catalyst, based on the total weight of the monomers, and also in the presence of a chain transfer agent and, if necessary, an aid under conditions of a polymerization pressure of 500-4000 Kg/cm2, preferably 1000-3500 Kg/cm2 and a reaction temperature of 50�-400� C., preferably 100�-350� C.
The free radical catalysts may be ordinary initiators such as peroxides, hydroperoxides, azo compounds, amine oxide compounds, oxygen and the like.
The chain transfer agents include, for example, hydrogen, propylene, butene-1, saturated aliphatic hydrocarbons and halogenated hydrocarbons having 1-20 carbon atoms or a greater number of carbon atoms, e.g. methane, ethane, propane, butane, isobutane, n-hexane, n-heptane, cycloparaffins, chloroform, carbon tetrachloride, saturated aliphatic alcohols having 1-20 or greater carbon atoms, e.g. methanol, ethanol, propanol, isopropanol and the like, saturated aliphatic carbonyl compounds having 1-20 or greater carbon atoms, e.g. carbon dioxide, acetone, methyl ethyl ketone and the like, and aromatic compounds such as toluene, diethylbenzene, xylene and the like.
The epoxy group-containing olefin polymers used in the present invention may be olefin homopolymers or copolymers modified by graft reaction thereto of the unsaturated glycidyl group-containing monomers.
The olefin polymers for these purposes are, for example, homopolymers such as low, medium and high density polyethylene, polypropylene, polybutene-1, poly-4-methylpentene-1 and the like, copolymers of a major proportion of ethylene and other alpha-olefins such as ethylenepropylene copolymers, ethylene-butene-1 copolymers, ethylene-hexene-1 copolymers, ethylene-4-methylpentene-1 copolymers, ethylene-octene-1 copolymers and the like, copolymers of a major proportion of propylene and other alpha-olefins such as propylene-ethylene block copolymers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-methacrylic acid copolymers, copolymers of ethylene and methyl, ethyl, propyl, isopropyl and butyl esters of acrylic acid or methacrylic acid, ethylene-maleic acid copolymers, ethylene-propylene copolymer rubbers, ethylene-propylene-diene copolymer rubbers, liquid polybutadiene, ethylene-vinyl acetate-vinyl chloride copolymers, and mixtures thereof. These polymers may be further mixed with other types of synthetic resins or rubbers.
The ethylenically unsaturated fatty acids and derivatives thereof are, for example, acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, maleic anhydride, citraconic anhydride, itaconic anhydride, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, monoethyl or diethyl maleate, acrylic amide, methacrylic amide, maleic monoamide, sodium acrylate, sodium methacrylate, potassium acrylate, potassium methacrylate, and the like. Of these, maleic anhydride is most preferable.
In the practice of the invention, an ethylenically unsaturated fatty acid or derivative thereof is subjected to graft reaction with the epoxy group-containing olefin polymer in the presence of a radical generator.
The graft reaction may be carried out by several methods including a method using radical initiators, a method utilizing plasma, and a method in which temperatures are raised to produce thermal radicals. Of these, the method using radical initiators is preferred because of the inexpensive apparatus, convenience and high reactivity.
The radical initiators may be organic peroxides and azo nitriles. Examples of the organic peroxides include ketone peroxides such as methyl ethyl ketone peroxide, cyclohexane peroxide and the like, peroxy ketals such as 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-butylperoxy)cyclohexane and the like, hydroperoxides such as t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide and the like, dialkyl peroxides such as di-t-butyl peroxide, t-butyldicumyl peroxide, dicumyl peroxide, α,α'-bis(t-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 2,5-dimethyl-2,5-di(t-butylperoxy)hexine-3 and the like, diacyl peroxides such as benzoyl peroxide, octanoyl peroxide, decanoyl peroxide and the like, peroxydicarbonates such as diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate and the like, and peroxy esters such as t-butyl peroxyacetate, t-butyl peroxyisobutylate, t-butyl peroxybenzoate and the like. Examples of azonitriles include azobisisobutyronitrile, azobisisopropionitrile and the like. These compounds are properly selected depending on the reaction conditions such as reaction solvent, reaction temperature and the like.
The reaction using the radical initiators may be carried out by a number of methods. For instance, there are mentioned a method in which the reaction is effected in the state of a solution using a medium which is a good solvent for epoxy group-containing olefin polymers (solution reaction), a method in which the reaction is effected in the state of a suspension using a medium which is a poor solvent for epoxy group-containing olefin polymers (suspension reaction), and a method in which the reaction is effected without use of any medium while heating and mixing epoxy group-containing olefin polymers at temperatures higher than the melting or softening point thereof (melt reaction). The mediums used for the solution reaction include aliphatic hydrocarbons such as hexane, heptane, octane, cyclohexane, decaline and the like, aromatic hydrocarbons such as benzene, toluene, xylene, tetralin and the like, and polar solvents such as dichlorobenzene, chloroform, carbon disulfide, carbon tetrachloride, trichloroethane and the like. The mediums suitable for the suspension reaction are, for example, water. For the melt reaction, it is usual to use extruders, kneaders, Banbury mixers and rolls ordinarily used for processing of plastics or rubbers. The reaction conditions should be appropriately selected. The reaction should be effected at temperatures which permit the olefin polymer to melt and the radial initiator to sufficiently decompose within the reaction time. If the temperature is too high, epoxy group-containing olefin polymers or ethylenically unsaturated fatty acids may decompose, causing side reaction to occur. Accordingly, the temperature is preferably in the range of approximately 100�-300� C.
The amount of addition of the ethylenically unsaturated fatty acid is selected from a range of 0.01-10 parts by weight, preferably 0.1-5 parts by weight, per 100 parts by weight of the epoxy group-containing olefin polymer. If the amount is less than 0.01 part by weight, the adhesion strength is not improved and thus the desired effect cannot be attained. On the other hand, when the amount exceeds 10 parts by weight, the resulting resin is colored or gelatin proceeds, thus causing foreign matters to be unfavorably produced.
The adhesive resin obtained in the present invention may be used as adhesive resin compositions by mixing with polyolefins in desired mixing ratio.
In the practice of the invention, both the unsaturated glycidyl group-containing monomer and the ethylenically unsaturated fatty acid may be added to the olefin polymer at the same time.
According to the second embodiment of the invention, the adhesive resin or an olefin polymer composition comprising the adhesive resin is used for lamination with other materials to obtain laminate articles having at least two layers.
Other materials used in the present invention are thermoplastic resins, thermosetting resins, rubbers, metals, cloths, paper, wood and glass.
More particularly, such materials include: olefin polymers including homopolymers such as low, medium and high density polyethylene, polypropylene, polybutene-1, poly-4-methyl-pentene-1 and the like, copolymers of a major proportion of ethylene and other alpha-olefins such as, for example, ethylene-propylene copolymers, ethylene-butene-1 copolymers, ethylene-hexene-1 copolymers, ethylene-4-methylpentene-1 copolymers and the like, copolymers of a major proportion of propylene and other alpha-olefins such as propylene-ethylene block copolymers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-methacrylic acid copolymers, copolymers of ethylene and methyl, ethyl, propyl, isopropyl, butyl esters of acrylic of methacrylic acid, ethylene-maleic acid copolymers, ethylene-vinyl acetate-vinyl chloride copolymers, and mixtures thereof; other thermoplastic resins including saponified ethylene-vinyl acetate copolymers, polyamide resins, polycarbonate resins, polyvinyl chloride resins, polyvinylidene chloride resins, polyester resins, polyacrylonitrile resins, polystyrene resins, polyvinyl alcohol resins, ABS resins, polymethacrylates, fluorocarbon resins, polyimide resins, polyamideimide resins, polyether/ether ketone resins, polyethersulfone resins, polysulfone resins, polyphenylene oxide resins, polyphenylene sulfide resins, polyacetal resins and mixtures thereof; thermosetting resins such as phenolic resins, urea resins, melamine resins and the like; and rubbers.
Examples of rubbers include synthetic rubbers such as polybutadiene, polyisoprene, neoprene rubber, ethylene-propylene copolymers, ethylene-propylene-diene copolymers, styrene-butadiene copolymer, styrene-acrylonitrile-butadiene copolymer, butyl rubber, polyurethane rubber, chlorosulfonated polyethylene, chlorinated polyethylene, fluororubbers, thiokol and the like, and natural rubbers.
Sheets of the synthetic resins or rubbers mixed with fillers may be also used in the present invention.
The fillers for these purposes include, for example, powdery and particulate fillers such as calcium carbonate, magnesium carbonate, calcium sulfate, calcium silicate, clay, diatomaceous earth, talc, alumina, quartz sand, glass powder, iron oxide, metal powders, antimony trioxide, graphite, silicon carbide, silicon nitride, silica, boron nitride, aluminum nitride, wood powder, carbon black and the like; plate-like or flaky fillers such as mica, glass, sericite, pyrophyllite, metal foils such as aluminum flake, graphite and the like; hollow fillers such as Shirasu balloons, metal balloons, glass balloons, pumice stone and the like; fibrous fillers such as glass fibers, carbon fibers, graphite fibers, whiskers, metal fibers, silicon carbide fibers, mineral fibers, e.g. asbestos and wollastonite, and organic fibers such as viscose, polyamide and vinylon fibers; and textile fillers such as glass fiber mats, organic fiber mats and the like.
Other substrate materials include metal foils, metal sheets, metal gauzes and punched plates of metals such as chromium, iron, nickel, zinc, tin, aluminum, copper, brass, galvanized steel and the like.
Cloths that can be employed as substrates include non-woven or woven fabrics or nettings of fibers such as tape yarns and monofilaments obtained from the thermoplastic resins indicated before, split films obtained by finely cutting films of the thermoplastic resins, woven fabrics of synthetic fibers such as vinylon and tetron fibers or natural fibers such as cotton, silk and hemp fibers, and woven fabrics, mats and felts of fibers such as glass fibers, carbon fibers and metal fibers.
Paper sheets used as a substrate material may not be critical and include, for example, packaging papers such as kraft paper, roll paper and the like, thin papers such as glassine paper, paperboards and other machine-made papers, Japanese papers such as shoji paper, and synthetic papers such as polystyrene paper, vinylon paper and the like.
Examples of the multi-layer laminates using different types of materials include polyester resin layer (hereinafter abbreviated as PET)/adhesive resin layer (hereinafter abbreviated as MEGA)/high density polyethylene layer (hereinafter abbreviated as HDPE), PET/MEGA/saponified ethylene-vinyl acetate copolymer (hereinafter abbreviated as saponified EVA), PET/MEGA/aluminum, PET/MEGA/paper, PET/MEGA/PET, PET/MEGA/PET/ethylene-butene-1 copolymer (hereinafter abbreviated as LLDPE), and the like.
The method of making the laminated product is not critical and includes, for example, blown film extrusion using multi-layer dies, flat film extrusion using T-dies, blow molding, injection molding, brush application, fluidized bed coating, powder spray coating, electrostatic coating, press molding and the like.
In the practice of the invention, various forms of materials including films, sheets, plates, bars, pipes, woven fabrics, and other processed articles may be bonded.
Moreover, various additives may be used in the range of amount not impeding the purposes of the invention. Examples of such additives include antioxidants, UV absorbers, flame retardants, copper deactivators, processability improvers, reinforcing agents, fillers, colorants, pigments, antistatic agents, antiblock agents, foaming agents and the like.
The present invention is more particularly described by way of examples and comparative examples.
1.7 kg of ethylene and 30 g of glycidyl methacrylate comonomer were charged into a 3.8 liter autoclave, followed by copolymerizing in the presence of di-tertiary-butyl peroxide under conditions of a pressure of 1700 kg/cm2 �g and a temperature of 170� C., thereby obtaining 100 parts by weight of ethylene-glycidyl methacrylate copolymer (hereinafter referred to simply as Et-GMA). This Et-GMA copolymer was subjected to graft reaction with 0.25 part by weight of maleic anhydride in a plastograph in the presence of 0.015 part by weight of dicumyl peroxide at a temperature of 190� C. for a reaction time of 7 minutes. The resulting product (referred to simply as Et-GMA/MAn) was washed with acetone and made into a thin film, followed by quantitative determination of the amount of combined maleic anhydride by infrared spectroscopic analysis. The results are shown in Table 1 given hereinafter.
The above procedure was repeated using a different amount of the comonomer, thereby obtaining another adhesive resin. The results are also shown in Table 1.
These adhesive resins were used for adhesion to PET and other substrate materials and the resulting laminates were subjected to measurement of interlaminar bond strength with the results shown in Table 1. The interlaminar bond strength was measured under the following conditions.
PET, saponified EVA, HDPE and Al sheets, each having a thickness of 2 mm, were each placed over an adhesive resin sheet having a thickness of 1 mm, which was backed by a 50 μm thick Al foil for its reinforcement. The sheet assemblies were preheated for 5 minutes, and then pressed under conditions of 240� C. and 50 kg/cm2 �5 minutes for PET and under conditions of 180� C. and 50 kg/cm2 �5 minutes for the other materials. Each laminate was subsequently cooled and cut to a width of 25 mm to give a test piece.
The test pieces were subjected to 180� peeling test at a pulling rate of 50 mm/minute, and the values determined were given as the interlaminar bond strength.
The general procedure of Example 1 was repeated using, as the comonomers, glycidyl methacrylate and ethyl acrylate to obtain a terpolymer of ethylene-glycidyl methacrylate-ethyl acrylate (hereinafter referred to as Et-GMA-EA), followed by graft reaction in the same manner as in Example 1 to obtain a melic anhydride grafted polymer (hereinafter referred to simply as Et-GMA-EA/MAn). Thereafter, an adhesion test was conducted in the same mannner as in Examples. The results are shown in Table 1.
One hundred parts by weight of the adhesive resin obtained in Example 2 was blended with 200 parts by weight of ethylene-ethyl acrylate copolymer having an ethyl acrylate content of 19 wt % and a melt index of 5.3 g/10 minutes. The blend was used for the adhesion test in the same manner as in Example 1. The results are also shown in Table 1.
Ethylene-ethyl acrylate copolymer having an ethyl acrylate content of 19 wt % and a melt index of 5.3 g/10 minutes, ethylene-vinyl acetate copolymer having a vinyl acetate content of 15 wt % and a melt index of 1.5 g/10 minutes (hereinafter referred simply as EVA), and maleic anhydride-modified low density polyethylene having a density of 0.92 g/ml and a melt index of 1.0 g/10 minutes (trademark; N Polymer L6100, made by Nippon Petrochemical Co., Ltd.) (hereinafter referred to as N Polymer) were used, as adhesive resins, for adhesion to several substrate materials in the same manner as in Example 1. The results are shown in Table 1.
TABLE 1__________________________________________________________________________ Amount of Comonomer Bond Strength (kg/25 mm in width)Example/ Adhesive Combined MI SaponifiedComp. Ex. Resin (wt %) (g/10 min.) PET EVA HDPE Al__________________________________________________________________________Example 1 Et-GMA/MAn GMA = 5.0 0.5 breakage of 13.0 breakage of breakage of MAn = 0.14 material material materialExample 2 Et-GMA/MAn GMA = 14.0 0.4 breakage of 13.5 breakage of breakage of MAn = 0.14 material material materialExample 3 Et-GMA-EA/MAn GMA = 5.1 0.3 breakage of 13.2 breakage of breakage of EA = 15 material material material MAn = 0.14Example 4 Et-GMA/MAn + GMA = 4.7 2.4 breakage of 13.1 breakage of breakage of EEA blend MAn = 0.05 material material materialComp. Ex. 1 EEA EA = 19 5.3 0.7 0.8 breakage of 9.7 materialComp. Ex. 2 EVA VA = 15 1.5 0.7 0.8 breakage of 12.7 materialComp. Ex. 3 N Polymer -- 1.0 1.5 5.0 breakage of 8.5 material__________________________________________________________________________
The adhesive resins of the invention have good adhesion force and wide utility in the field of coating on and lamination with other materials. They are applicable as a solution in solvent, or by a powder coating method.
Thermoplastic resins including olefin polymers such as polyethylene, polypropylene, ethylene-alpha-olefin copolymers, ethylene-vinyl acetate copolymers and the like may be added to the adhesive resins for dilution.
Laminated sheets, films, or other articles consisting of at least two layers, one of which is made of the adhesive resin, have a high interlaminar bond strength, and can also be readily heat-sealed with other types of materials. Three-layer or multi-layer laminates such as of PET/adhesive resin/polyolefin or saponified EVA make use of the characteristics of polyester, e.g. low gas permeability and high resistance to oil and heat, along with good characteristics of the other materials. These laminates will be utilized as food wrap films, food packaging bottles for mayonnaise, soy sauce, beer, carbonated drinks, oil and the like, films or bottles for wrapping medicines, and gasoline tanks.
|Cited Patent
|Filing date
|Publication date
|Jul 17, 1974
|Apr 27, 1976
|Mitsui Petrochemical Industries Ltd.
|Process for preparation of polyolefin graft copolymers
|Jun 25, 1976
|May 31, 1977
|E. I. Du Pont De Nemours And Company
|Process for making grafted polymeric material
|Citing Patent
|Filing date
|Publication date
|Apr 6, 1987
|Nov 22, 1988
|Kabushiki Kaisha Hosokawa Yoko
|Retortable pouch and packaging material for the retortable pouch
|Sep 24, 1990
|Jan 21, 1992
|Monsanto Company
|Composite of a styrenic polymer adhered to a polyolefin
|Mar 23, 1993
|Jan 11, 1994
|E. I. Du Pont De Nemours And Company
|Adhesives for laminating vinyl to various substrates
|Sep 12, 1991
|Feb 15, 1994
|University Of Massachusetts
|High performance blends of aromatic polyimides with aromatic polyethersulfones
|Jan 14, 1997
|Jul 18, 2000
|Ticona Celstran, Inc.
|Coated, long fiber reinforcing composite structure and process of preparation thereof
|Jul 3, 1997
|Jul 3, 2001
|Elf Atochem S.A.
|Multilayer structure comprising a binder and a layer of polyketone
|Nov 5, 1997
|Nov 26, 2002
|Toray Industries, Inc.
|Laminate containing a layer composed of polyphenylene sulfide blended with other polymers
|Dec 11, 1997
|Apr 20, 2004
|Toray Industries, Inc.
|Laminates for making electroconductive fuel tubes
|Nov 7, 2001
|Jul 12, 2005
|Matsushita Electric Works, Ltd.
|Resin moldings
|Apr 16, 2004
|Jan 20, 2009
|Exxonmobil Chemical Patents Inc.
|Tie-layer materials for use with ionomer-based films and sheets as skins on other materials
|Mar 19, 2004
|May 5, 2009
|3M Innovative Properties Company
|Acrylic-based thermally conductive composition and thermally conductive sheet
|Jun 13, 2007
|Nov 3, 2009
|Nippon Sheet Glass Co., Ltd.
|Glass composition and laminated glass
|Apr 28, 2006
|Aug 2, 2011
|Mitsubishi Chemical Corporation
|Acid-modified polypropylene resin, method for producing same, and resin composition using same
|May 24, 2004
|Dec 13, 2011
|Exxonmobil Chemical Patents Inc.
|Tie-layer materials for use with ionomer-based films and sheets as skins on other materials
|Nov 7, 2001
|Sep 19, 2002
|Matsushita Electric Works, Ltd.
|Resin moldings
|Jun 27, 2001
|Sep 18, 2003
|Hironobu Iyama
|Insulating resin composition, adhesive resin composition and adhesive sheeting
|Mar 12, 2003
|Dec 18, 2003
|William Shepler
|Multilayer storage container
|Apr 16, 2004
|Dec 2, 2004
|Domine Joseph Dominic
|Tie-layer materials for use with ionomer-based films and sheets as skins on other materials
|Nov 29, 2005
|Jun 29, 2006
|Sumitomo Chemical Company, Limited
|Shaped article
|Mar 19, 2004
|Nov 9, 2006
|Yuji Hiroshige
|Acrylic-based thermally conductive composition and thermally conductive sheet
|May 24, 2004
|Mar 8, 2007
|Domine Joseph D
|Ionomer laminates, composite articles, and processes for making the same
|Aug 10, 2004
|Mar 8, 2007
|Yuji Hiroshige
|Foam sheet-forming composition, heat conductive foam sheet and process for the production thereof
|Jan 13, 2005
|Aug 2, 2007
|Yuji Hiroshige
|Flame-retardant acrylic-based thermally conductive sheet
|Jun 13, 2007
|Oct 11, 2007
|Nippon Sheet Glass Co., Ltd.
|Glass composition and laminated glass
|Jul 12, 2005
|Oct 25, 2007
|3M Innovative Properties Company
|Thermally Conductive Composition
|Apr 28, 2006
|Mar 12, 2009
|Mitsubishi Chemical Corporation
|Acid-modified polypropylene resin, method for producing same, and resin composition using same
|Apr 9, 2010
|Aug 5, 2010
|3M Innovative Properties Company
|Foam sheet-forming composition, heat conductive foam sheet and process
|Nov 5, 2012
|May 8, 2014
|Stefanos L. Sakellarides
|Lidding structure based on aromatic polyester film, coextruded with a sealable/peelable epoxy-containing thermoplastic polymer
|Jun 27, 2001
|Apr 16, 2003
|Sumitomo Chemical Company, Limited
|Insulating resin composition, adhesive resin composition and adhesive sheeting
|Jun 27, 2001
|Jun 23, 2004
|Sumitomo Chemical Co
|Insulating resin composition, adhesive resin composition and adhesive sheeting
|Sep 23, 1997
|May 22, 1998
|Aztec Peroxides, Inc.
|Composition and method for producing a reinforced polymeric article by pultrusion molding
|U.S. Classification
|442/149, 428/414, 428/461, 428/513, 428/476.9, 428/418, 428/518, 206/524.1, 428/417, 428/419, 428/413, 428/483, 442/263, 428/441, 426/127, 428/412, 428/576, 428/422, 428/473.5, 428/519, 428/421, 428/520
|International Classification
|Cooperative Classification
|European Classification
|Jul 12, 1985
Owner name: NIPPON PETROCHEMICALS CO., LTD., 3-1, 1-CHOME, UCH
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNORS:KOJIMA, SHINJI;SUZUKI, HIROKAZU;ORIKASA, YUICHI;REEL/FRAME:004430/0679
Effective date: 19850601
|Aug 17, 1990
|Fee payment
Year of fee payment: 4
|Aug 22, 1994
|Fee payment
Year of fee payment: 8
|Oct 20, 1998
|Maintenance fee reminder mailed
|Mar 28, 1999
|Lapse for failure to pay maintenance fees
|Jun 8, 1999
|Expired due to failure to pay maintenance fee
Effective date: 19990331


text:
This is common for Gigantea the Thailand strain. The common form I had
grown for years with out ever seeing a hint of a flower. That was until
several years ago when I made it a goal to get it to flower. I put the
plant on a timed watering system and hit it with a lot of fertilizers in
the hopes of it producing a inflorescence. At the end of summer it did
flower and the flowers were much the same as on the Thailand strain but
they were not as developed. One of the oddest things was the fact that
in this situation the plant which commonly suckered for me started
producing runners which I have never seen on a gigantea before. This
form seems much different than the other clone having odd growths under
the leaves never flowering and constantly suckering. They tend to act
much like to separate species but the flower were unmistakable for this
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