A new FTIR-ATR cell for drug diffusion studies

The drug diffusion of most compounds, particularly hydrophilic molecules through the skin is limited by the permeation of the outermost cell layers of the epidermis, the stratum corneum(SC). For this reason it is of interest to characterize drug diffusion processes through this skin layer. A new FTIR-ATR cell was developed for non-invasive real time measurements of drug diffusion. The diffusion of water through an artificial polyethyleneglycol-polydimethylsiloxane membrane was studied. Additionally the diffusion of urea in human SC was analyzed. Based on a mathematical model the diffusion coefficients were derived. We could reveal that this cell associates the advantages of the Franz diffusion cell and the FTIR-ATR spectroscopy as a new powerful method for determining drug diffusion through biological membranes.     

LiSr2(NCN)I3: the first empty tetrahedral strontium(II) entity coordinated by carbodiimide units but without strontium-strontium bonding

LiSr(2)(NCN)I(3), the first extended compound containing empty tetrahedral Sr(4) entities, is synthesized using a new flux route, and it exhibits two interpenetrating three-dimensional networks made up from Sr tetrahedra capped by NCN(2-) anions on their triangular faces and vertex-sharing LiI(6) octahedra.     

Selective Catalytic Reduction of Nitric Oxide by Ammonia over Ag and Zn‐Exchanged Cuban Natural Zeolites

The catalytic selective reduction of NO over metal‐exchanged (Zn^II, Ag^I) natural zeolites (mordenite and clinoptilolite) from Cuba using NH₃ as a reducing agent in the presence of excess oxygen was studied. Both transition metals slightly improve the catalytic performance for the NO reduction. Zn^II‐exchanged zeolites exhibit a moderate catalytic activity, with conversions of NO of ≈58 % and high selectivity to N₂ at high temperatures.     

Evasion and Prediction II

A subgroup G Z exhibits the Specker phenomenon if every homomorphismG Z maps almost all unit vectors to 0. We give several combinatorialcharacterizations of the cardinal e, the size of the smallestG Z exhibiting the Specker phenomenon. We also prove the consistencyof > e, where is the unbounding number and e the evasionnumber. Our results answer several questions addressed by Blass.     

Lech's Conjecture on Deformations of Singularities and Second Harrison Cohomology

Let B₀ be a local singularity of dimension d. Then we considerthe problem of Lech, whether for every deformation (A, m) (B,n) of B₀ the inequality between the Hilbert functions is true,and give a positive answer in the case that the formal versaldeformation of B₀ is a base change of an algebraic family (R,M) (S, N), where R is regular and dim S = dim R + d. So one would hope to lift versal deformations in that way. Thereare obstructions against this in certain second Harrison cohomologygroups.     

Efficient Deposition of Semiconductor Powders for Photoelectrocatalysis by Airbrush Spraying

Powder catalysts were deposited as thin films on transparent conductive oxides (TCO) by means of an airbrush spray coating technique. Photoelectrocatalytic properties of the powder catalysts were characterized using photocurrent spectroscopy at different wavelengths demonstrating on the one hand the stability of the films and on the other hand the electrical connection with the electrode surface. The morphology and thickness of the deposited powder catalyst films on TCO were characterized using scanning electron microscopy. Aiming at photocatalytic water splitting, semiconductor powders like gallium oxide (Ga₂O₃) and zinc oxide (ZnO) were used as test samples to optimize the deposition technique resulting in thin homogeneous layers and good adhesion on the conductive substrate. The proposed airbrush deposition technique of powder catalysts allows closing an experimental gap between microheterogeneous systems and modified electrodes for finding suitable materials for photoelectrochemical water splitting.