The free solution electrophoretic mobilities of poly(styrenesulfonate), ss-DNA, and duplex DNA are measured by capillary electrophoresis across a range of ionic strengths and, for poly(styrenesulfonate) and ss-DNA, across a range of chain lengths. The data are then compared with mobilities reported in the literature and predicted by theory. For ionic strengths below 0.1 M, the capillary method is more accurate and rapid than previous techniques; it also provides a distribution of mobility values for polyelectrolyte mixtures. A maximum of the free solution mobility with respect to chain length is discovered in the oligomer range for both poly(styrenesulfonate) and ss-DNA; lowering ionic strength accentuates this unexplained phenomenon. In the large chain limit, where the mobility is independent of chain length, the ionic strength dependences of mobility for all three polymers are remarkably similar. These dependences can only be explained by models that incorporate nonlinear electrostatic effects into the description of the counterion cloud. The Manning model (with relaxation correction) best approximates the dependence of mobility on ionic strength.

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The human skin microbiome has been suggested to play an essential role in maintaining health by contributing to innate defense of the skin. These observations have inspired speculation that the use of common skin washing techniques may be detrimental to the epidermal antibacterial defense system by altering the microbiome. In this study, several common skin cleansers were used to wash human forearms and the short-term effect on the abundance of the antimicrobial peptide LL-37 and the abundance and diversity of bacterial DNA was measured. Despite small but significant decreases in the amount of LL-37 on the skin surface shortly after washing, no significant change in the bacterial community was detected. Furthermore, Group A Streptococcus did not survive better on the skin after washing. In contrast, the addition of antimicrobial compounds such as benzalkonium chloride or triclocarban to soap before washing decreased the growth of Group A Streptococcus applied after rinse. These results support prior studies that hand washing techniques in the health care setting are beneficial and should be continued. Additional research is necessary to better understand the effects of chronic washing and the potential impact of skin care products on the development of dysbiosis in some individuals.

SYNOPSISThe effective sphere approximation for modeling electrophoretic transport of macromolecules in highly porous gels (the "Ogston model") is examined, and contrasted with similar mobility models for stiff and flexible solutes. Calculation of segmental depletion near gel obstacles of various shapes demonstrates the limited applicability of the effective sphere approach. For highly flexible chains, both theory and experiment reveal a nonunique mapping between mobility and molecular size when the molecular radius is comparable to that of gel fibers. Turning to mobility behavior in more concentrated gels, neither flexible or stiff macromolecules behave as spheres; for the particular case of flexible chains, the presence of entropic barriers in concentrated gels can be understood in terms of a simple random planes model for the gel structure.

The studies presented in this paper support occlusion of the dentine surface upon the deposition of an arginine-rich layer together with copolymer and phosphate ions from an alcohol-free mouthwash containing 0.8% arginine, PVM/MA copolymer, pyrophosphates and 0.05% sodium fluoride.