Decrease In Cl Concentration Research Articles

Lyophilized histidine investigated using X-ray photoelectron spectroscopy and cryogenics: Deprotonation in vacuum

Lyophilized histidine samples were investigated using X-ray photoelectron spectroscopy (XPS). Lyophilized samples were prepared from aqueous solutions at a pH in the range between ∼1.5 and ∼10, and with no further addition of electrolyte. The use of cryogenics allowed the determination of protonated to unprotonated molar ratios of sites in l-histidine, which correlates well with the dissociation constants of the residual amino acid sites. When cryogenics was not used deprotonation of the lyophilized samples occurred, where the degree and the total concentration of deprotonated sites correlates well with the formation constants and the decrease in Cl concentration, respectively. This later relation clearly indicates a correlation between deprotonation and the desorption of HCl from lyophilized samples.

Fabrication of amorphous boron–carbon–nitrogen films by hot-wire CVD

Amorphous boron–carbon–nitrogen (a-BCN) films have been fabricated by hot-wire chemical vapor deposition using BCl 3, C 2H 2 and N 2 or NH 3. The N concentration of the films fabricated by using a N 2 was below several at.%, and Cl atoms were incorporated to 3–5 at.%. Whereas the N concentration increased and the Cl concentration decreased by using NH 3 gas. In the case of NH 3 gas, the N concentration was nearly equal to the B concentration in most cases. The nearly equal concentrations in N and B resulted from high chemical reactivity between the BCl 3 and NH 3 gases, and the decrease in Cl concentration resulted from the removal as HCl due to NH 3 gas. These results indicate that the combination of BCl 3 and NH 3 is suitable for fabrication of a-BCN films by the CVD method.

Regulation of ion content in primary cultures from reabsorptive ducts of human sweat glands studied by X-ray microanalysis.

X-ray microanalysis was used to investigate whether cAMP- and/or Ca2+-activated regulation of chloride and potassium efflux is expressed in primary cultures of sweat gland duct cells. The effects of extracellular UTP and ATP on the duct cells, and the signalling system involved in the response to ATP was also studied. Primary cultures from duct cells of human sweat glands responded to 1 microM carbachol, 2 microM of the Ca2+ ionophore A23187, or 5 mM 8-bromo-cAMP stimulation for 5 min, resulting in a decrease in cellular Cl and K concentrations. 50 microM 5-nitro-2-(3-phenylpropyl-amino)-benzoic acid (NPPB), a Cl- channel blocker, can inhibit the decrease in Cl concentration induced by cAMP. Extracellular (200 microM) ATP caused a decrease of Cl and K in cultured duct cells, while (200 microM and 2 mM) UTP was ineffective. Both the phosphoinositidase C inhibitor U73122 (10 microM) and the absence of extracellular Ca2+ abolished the ATP-induced decrease in Cl and K content. Alloxan (1.25 mM), an adenylate cyclase inhibitor, had an inhibitory effect on the response to ATP. The decrease in K, but not in Cl, content in the cells elicited by ATP was blocked by prior incubation with 100 ng/ml pertussis toxin, indicating the coupling of ATP to pertussis toxin-sensitive G-proteins. In conclusion, both Ca2+- and cAMP-dependent Cl- permeability is present in primary cultures from duct cells of human sweat gland. The response to ATP can be mediated both by Ca2+- and by cAMP-dependent pathways, and is coupled to pertussis toxin-sensitive G-proteins.

NaCl Formation in Spray-Deposited SnO2:F Films

Pyrolytically deposited SnO{sub 2} films on soda glass were analyzed by SEM, XRD, SAM, and XPS. The films were deposited at different temperatures and time periods. Some films revealed large NaCl crystals situated in holes or on the surface; other films were topologically smooth. However, small NaCl crystallites were observed in all films. The XPS analyses revealed that all Cl was bound to Na in the form of NaCl and two Auger Cl peaks were observed in all samples. The lower energy Auger Cl peak resulted from bulk NaCl, whereas the second peak, shifted by 10 eV toward higher kinetic energy, was associated with the SnO{sub 2}/NaCl interface. Annealing of the SnO{sub 2} films revealed a large decrease in Cl concentration. The excess Na is associated with the SnO{sub 2} matrix, most likely in two forms, interstitially in the film lattice as well as in the form of Na{sub 2}SnO{sub 3}.