Adsorption layers of β-casein formed at the interface between air and a buffer including various concentrations of guanidine hydrochloride (GuHCl) were studied by neutron reflectivity and by bubble tensiometry. A transition in the structure and in the properties of the adsorption layer seems to occur around a GuHCl concentration of 1.5 M. The data are interpreted assuming that the adsorbed protein molecules behave like multiblock copolymers with alternating hydrophilic and hydrophobic sequences. Below the transition, the hydrophilic coils and the hydrophobic two-dimensional blocks have a fractal dimension larger than that beyond the transition where they have the features of either two-dimensional or three-dimensional excluded volume coils. The effect of temperature on these phenomena indicates that they are not dominated by hydrophobic interactions. Thus, the attractions between amino acids which are broken by GuHCl might be hydrogen bonds which are frequently encountered in the secondary structure of polypeptide chains. These results show that even with the flexible polypeptide chain of β-casein, interactions between amino acids contribute significantly to the structure of the adsorption layer formed from a buffer devoid of denaturing agent.
We investigate the electrical behavior of a symmetric liquid crystal (LC) cell: elecrode-silane-LC-silane-electrode. The silane (chlorodimethyloctadecyl-silane) layer induces a homeotropic orientation of the nematic liquid crystal (NLC) molecules. The wettability technique is used to detect the change of the surface energy of the electrode upon cleaning and silane layer deposition. We report on the dynamic impedance measurements of the nematic liquid crystal cell. It is found that the silane alignment layer has a blocking effect on the liquid crystal (LC) cell. We also study the relaxation behavior of the cell which is later assimilated as an electrical equivalent circuit.
SUMMARYThis paper presents the application of an iterative method for fast computation of microstrip interdigital capacitor (IDC) and a quasi-lumped miniaturized "lter. The use of a 2D-FFT algorithm allows simpli"cations in the calculation process leading to accurate results obtained 20 times faster than in the conventional method cases.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.