Cracking can allow moisture to penetrate and corrode the reinforcement. Antibiotics alone are not effective because they may not penetrate infected tissues sufficiently. Signals in the ELF frequency range, however, can penetrate much deeper. These pila could often penetrate enemy shields and hit the soldiers behind them. Sperm typically cannot penetrate it. These tags are quantum dots attached to proteins that penetrate cell membranes. German snipers used armour-piercing bullets that allowed them to penetrate loopholes. Delay fuzes allow the shell to penetrate the ground before exploding. The platysma is vulnerable to neck injuries that may penetrate it. Bullets will not penetrate most objects, but they will break glass. To be effective in soil formation, water must penetrate the regolith. The bite did in fact penetrate his skin, but did not cause any notable harm. Preservative oils tend to not penetrate satisfactorily by this method. ACP whose large, slow bullet does not penetrate armor to any great extent. Then they penetrate the mucosa and submucosa and enter venules or lymphatics.