Spin Trapping Isotopically-Labelled Nitric Oxide Produced from [15n]L-Arginine and [17ojdioxygen by Activated Macrophages Using a Water Soluble Fe++-Dithiocarbamate Spin Trap

The unique capabilities of EPR spin trapping of nitric oxide based on a ferrous-dithiocarbamate spin trap have been demonstrated in a study verifying the source of the nitrogen and oxygen atoms in nitric oxide produced from activated macrophages. Spin trapping experiments were performed during nitric oxide generation from activated mouse peritoneal macrophages using the ferrous complex of N-methyl D-glucam-ine dithiocarbamate as a spin trap. When ¹⁵N-substituted arginine was given to the activated macrophages in the presence of the spin trap, a characteristic EPR spectrum of the nitric oxide spin adduct was obtained, which indicates the presence of the ^l5N atom in the nitric oxide molecule. The hyperfine splitting (hfs) constant of the ^l5N nucleus was 17.6 gauss. When ^l7O-containing dioxygen (55%) was supplied to the medium, an EPR spectrum consistent with the “O-substituted nitric oxide spin adduct was observed in the composite spectrum. The hfs of “O was estimated to be 2.5 gauss. The ^l4NO spin adduct observed after prolonged incubation in the medium which contains [^l5N]L-arginine as the only extracellular source of arginine demonstrates that arginine is recycled through its metabolite in activated macrophages.     

Opportunistic use of camera traps to assess habitat-specific mammal and bird diversity in northcentral Namibia

In northcentral Namibia, Waterberg Plateau Park (WPP) is a protected area that acts as a refuge for rare and endangered species, while the farmlands surrounding the Park are managed for livestock production, but support populations of wildlife for game farming, trophy hunting, and conservation. During June–October 2006, camera-traps were set within and surrounding WPP to assess leopard (Panthera pardus) density (n = 19 camera stations and 946 camera-trap-nights). Fortuitously, photographic results (2,265 photos of identifiable mammal (n = 37) and bird (n = 25) species) allowed us to assess aspects of species diversity and differences among the Park, the farmland areas along the Waterberg Plateau escarpment, and the flatlands surrounding the escarpment. Species composition among the three areas was markedly different, and made sense with respect to differences in habitat and management features. Camera-trapping efforts, although intended for a narrow purpose, may also provide a rather robust record of differences in mammal and bird diversity in adjacent habitats and can be incorporated into long-term monitoring programs.     

Detection of superoxide production in stimulated and unstimulated living cells using new cyclic nitrone spin traps

Reactive oxygen species (ROS), including superoxide anion and hydrogen peroxide (H₂O₂), have a diverse array of physiological and pathological effects within living cells depending on the extent, timing, and location of their production. For measuring ROS production in cells, the ESR spin trapping technique using cyclic nitrones distinguishes itself from other methods by its specificity for superoxide and hydroxyl radical. However, several drawbacks, such as the low spin trapping rate and the spontaneous and cell-enhanced decomposition of the spin adducts to ESR-silent products, limit the application of this method to biological systems. Recently, new cyclic nitrones bearing a triphenylphosphonium (Mito-DIPPMPO) or a permethylated β-cyclodextrin moiety (CD-DIPPMPO) have been synthesized and their spin adducts demonstrated increased stability in buffer. In this study, a comparison of the spin trapping efficiency of these new compounds with commonly used cyclic nitrone spin traps, i.e., 5,5-dimethyl-1-pyrroline N-oxide (DMPO), and analogs BMPO, DEPMPO, and DIPPMPO, was performed on RAW 264.7 macrophages stimulated with phorbol 12-myristate 13-acetate. Our results show that Mito-DIPPMPO and CD-DIPPMPO enable a higher detection of superoxide adduct, with a low (if any) amount of hydroxyl adduct. CD-DIPPMPO, especially, appears to be a superior spin trap for extracellular superoxide detection in living macrophages, allowing measurement of superoxide production in unstimulated cells for the first time. The main rationale put forward for this extreme sensitivity is that the extracellular localization of the spin trap prevents the reduction of the spin adducts by ascorbic acid and glutathione within cells.     

Detection of the Ethyl-and Pentyl-Radical Adducts of α-(4-Pyridyl-1-Oxide)-N-Ter J-Butylnitrone in Rat-Liver Microsomes Treated with ADP,NADPH and Ferric Chloride

HPLC-EPR analyses of the reaction mixtures of microsomal suspensions incubated with ADP, ferric chloride, NADPH and α-(4-pyridyl-1-oxide)-N-tert-butylnitrone (4-POBN) were performed. In the elution pattern of the reaction mixture, three peaks (peaks 1, 2 and 3) were detected. The radical adducts (1 and 3) were identified as being the pentyl- and ethyl-radical adducts of 4-POBN by comparing their retention times with those of the authentic radical adducts.     

The use of barrier-connected pitfall trapping for sampling predatory beetles and spiders

The efficiency of barrier-connected pitfall trapping was compared to conventional single traps or arrays. For ground-active beetles, the use of a pitfall system incorporating a wetting agent with five traps arranged in a cross formation connected by plastic barriers was more efficient than a single dry trap by at least an order of magnitude and at least twice as efficient as five traps without connecting barriers. It is argued that the efficiency of pitfall trapping may be improved markedly by using barrier-connected traps, particularly for some carabid and staphylinid beetles and lycosid spiders. Capture of linyphiids was not improved by the use of barriers and was dependent only on the use of wetting agent and number of traps used.     

Possible mechanisms for strand-breaks in DNA induced by stirring

When aqueous solutions of DNA are stirred at room temperature, strand breaks occur extensively. Using various spin-traps, coupled with epr spectroscopy, we have shown that this does not proceed via homolysis. It is suggested that breaks occur by hydrolysis at strongly bent regions, momentarily induced by the stirring.     

Evaluation of Superoxide Scavenging Activity of OPC-14117 By Electron Spin Resonance Technique

OPC-14117 is a potent drug which has both brain function activating effect and protective effect against cerebral ischemia. Occurrences of these effects might be expected due to superoxide dismutase-like activity of OPC-14117. The present study has been conducted to evaluate the active oxygen scavenging activity of OPC-14117 and to explain the mechanisms of its pharmacological activities. The reaction of OPC-14117 and superoxide anion. generated in potassium superoxide, was examined by electron spin resonance technique at both liquid nitrogen (77 K) and room (22°C) temperatures. OPC-14117 showed a higher superoxide scavenging activity than that of α-tocopherol in an aprotic solvent system. The active moiety of OPC-14117 to provide the scavenging effect was found due to the phenolic hydroxyl group of its indan skeleton.     

Spin Trapping by Use of N-Tert-Butylhydroxylamine. Involvement of Fenton Reactions

Spin trapping of short-lived R. radicals is done by use of N-tert-butylhydroxylamine (1) and H²O². The hydroxylamine is oxidized to the radical t-BuN(O)H (2) which is converted into the spin trap 2-methyl-2-nitrosopropane (3). Simultaneously, hydroxyl radicals. OH are formed from H²O². The latter radical species abstracts hydrogen atoms from suitable molecules HR to give R. radicals, which are trapped with the formation of aminooxyl radicals, i. e., t-BuN(O)R (4) detectable by EPR spectroscopy. The reaction is enhanced by the presence of iron ions. The cleavage of H²O² into. OH radicals is considered to involve both a radical-driven (t-BuN(O)H 2) and an iron-driven Fenton reaction.     

Inverse Optical Cavity Design for Ultrabroadband Light Absorption Beyond the Conventional Limit in Low‐Bandgap Nonfullerene Acceptor–Based Solar Cells

In the subwavelength regime, several nanophotonic configurations have been proposed to overcome the conventional light trapping or light absorption enhancement limit in solar cells also known as the Yablonovitch limit. It has been recently suggested that establishing such limit should rely on computational inverse electromagnetic design instead of the traditional approach combining intuition and a priori known physical effect. In the present work, by applying an inverse full wave vector electromagnetic computational approach, a 1D nanostructured optical cavity with a new resonance configuration is designed that provides an ultrabroadband (≈450 nm) light absorption enhancement when applied to a 107 nm thick active layer organic solar cell based on a low‐bandgap (1.32 eV) nonfullerene acceptor. It is demonstrated computationally and experimentally that the absorption enhancement provided by such a cavity surpasses the conventional limit resulting from an ergodic optical geometry by a 7% average over a 450 nm band and by more than 20% in the NIR. In such a cavity configuration the solar cells exhibit a maximum power conversion efficiency above 14%, corresponding to the highest ever measured for devices based on the specific nonfullerene acceptor used.     

贵州赤水桫椤国家级自然保护区鸟兽多样性红外相机初步监测

红外相机监测是了解野生动物多样性和威胁因素的重要手段。本研究采用网格法和分层抽样调查法, 在贵州赤水桫椤国家级自然保护区内选取20个监测位点布设红外相机, 对区内鸟兽物种多样性进行监测。2015年8月至2017年8月, 红外相机累计工作6,370个工作日, 共拍摄45,953张照片, 独立有效照片1,936张。准确鉴定出兽类4目8科19种, 鸟类4目11科28种, 其中, 国家II级重点保护野生动物7种。相对丰富度指数(RAI)排前五位的兽类依次是毛冠鹿(Elaphodus cephalophus)、鼬獾(Melogale moschata)、藏酋猴(Macaca thibetana)、小麂(Muntiacus reevesi)和野猪(Sus scrofa); 鸟类依次是紫啸鸫(Myophonus caeruleus)、红腹角雉(Tragopan temminckii)、灰胸竹鸡(Bambusicola thoracicus)、黑喉噪鹛(Garrulax chinensis)和棕颈钩嘴鹛(Pomatorhinus ruficollis)。物种积累曲线结果表明, 兽类稀疏化曲线在300天后趋于稳定, 表明监测取样已较充分, 而鸟类监测物种数随时间积累依旧保持增长趋势。