Visible light induced reversible extrusion of nitric oxide from a ruthenium(II) nitrosyl complex: a facile delivery of nitric oxide

The new ruthenium compound [Ru(NO)(pysiS4)]Br (3) (pysiS4 = 2,6-bis(3-triphenylsilyl-2-sulfanylphenylthiomethyl)pyridine), containing sterically bulky SiPh3 groups ortho to the thiolate donors, has been synthesized. In solution, 3 releases NO efficiently on exposure to visible light (lambda >/= 455 nm) at room temperature to afford [Ru(Br)(pysiS4)] (4). Treatment of 4 with NO yielded exclusively 3 without any metal-bound side reaction.     

STRATOSPHERIC OZONE DEPLETION BETWEEN 1979 and 1992: IMPLICATIONS FOR BIOLOGICALLY ACTIVE ULTRAVIOLET-B RADIATION and NON-MELANOMA SKIN CANCER INCIDENCE

Abstract— The depletion of stratospheric ozone (0₃) has predictable implications for increases in biologically damaging solar ultraviolet-B radiation (UVB,280–320 nm) reaching the earth's surface. A radiative transfer analysis of satellite-based O₃ measurements between January 1979 and December 1992 shows that surface UVB levels increased substantially at all latitudes except the tropics, if other factors such as cloud cover and local pollutant levels have remained constant over this period. Exposure to UVB radiation is known to induce basal cell and squamous cell skin cancers, and dose-response relationships derived from epidemiological data can be combined with the UVB enhancements to estimate the seasonal and latitudinal distribution of future expected increases in the incidence of these cancers.     

A natural 15N approach to determine the biological fixation of atmospheric nitrogen by biological soil crusts of the Negev Desert

Biological soil crusts are important cryptogamic communities covering the sand dunes of the north-western Negev. The biological crusts contain cyanobacteria and other free-living N(2)-fixing bacteria and are hence able to fix atmospheric nitrogen (N). This is why they are considered to be one of the main N input pathways into the desert ecosystem. However, up to now, in situ determinations of the N(2) fixation in the field are not known to have been carried out. We examined the natural (15)N method to determine the biological N(2) fixation by these soil crusts under field conditions. This novel natural (15)N method uses the lichen Squamarina with symbiotic green algae--which are unable to fix N(2)--as a reference in order to determine N(2) fixation. Depending on the sampling location and year, the relative biological fixation of atmospheric nitrogen was estimated at 84-91% of the total N content of the biological soil crust. The cyanobacteria-containing soil lichen Collema had a fixation rate of about 88%. These fixation rates were used to derive an absolute atmospheric N input of 10-41 kg N ha(-1) year(-1). These values are reasonable results for the fixation of atmospheric N(2) by the biological crusts and cyanolichens and are in agreement with other comparable lab investigations. As far as we are aware, the results presented are the first to have been obtained from in situ field measurements, albeit only one location of the Negev with a small number of samples was investigated.     

Synthese und Charakterisierung von Pr2InF und [K(15-Krone-5)2][Pr2InCl2]. Die Kristallstrukturen von [Pr2InCl] ∞ und [K(15-Krone-5)2][Pr2InCl2] Bernhard Neumüller

The reaction of ⁱPr₂InCl (1) with KF and 15-crown-5 in acetonitrile at room temperature leads to the toluene-soluble crown ether salt [K(15-crown-5)₂][ⁱPr₂InCl₂] (2) and to the MeCN-soluble diorganoindium fluoride ⁱPr₂InF (3). Pure 3 can be isolated, when the reaction is carried out with KF but without crown ether at −15°C. Crystals of 1 und 2, suitable for X-ray structure determinations, were obtained when 1 and 2 were recrystallized from toluene. 1 exists as infinite chains of the monomeric unit ⁱPr₂InCl, while the unit cell of 2 contains separate ions.     

8-羟基喹啉-硅胶介质的合成及其在海水中痕量铅检测的应用

详细研究了以大孔硅胶为基质,一步合成8羟-基喹啉(8-HQ)型金属螯合色谱填料的方法,采用正交试验对合成方法进行了优化。与传统合成方法所得的填料进行了比较,从理化指标等方面来看,新的合成方法为佳。将该法用作微柱流动注射(FIA)在线分离、富集和电感耦合等离子体质谱(ICP-MS)分析流程中的固定相,对大洋海水中的痕量铅进行了在线分析,得到了较满意的结果。     

Photochemical structuring and fixing of structures in binary polymer brush layers via 2pi+2pi photodimerization

Binary polymer brushes grafted to Si wafers were prepared from hydrophilic and hydrophobic polymer components, which allow switching the surface properties (as revealed by contact angles) by exposure to varying solvents. The hydrophilic component was poly-2-vinylpyridine; the hydrophobic component was a copolymer of styrene and 2-(4-vinylphenyl)indene containing the photodimerizable phenylindene chromophore. The brushes were prepared via thermal and via photochemical grafting-to methods, which led to distinct layer thicknesses. Structural patterns differing in surface properties were produced and fixed via crosslinking the hydrophobic component by 2pi+2pi photodimerization of phenylindene moieties. The patterns were visually observable.