Use of a handheld Raman spectrometer for fast screening of microbial pigments in cultures of halophilic microorganisms and in microbial communities in hypersaline environments in nature

A compact handheld Raman spectrometer equipped with a 532 nm excitation laser was used to detect pigments as possible biomarkers in autotrophic (cyanobacteria and purple sulfur bacteria) and heterotrophic halophilic microorganisms (Archaea of the family Halobacteriaceae, Salinibacter). Common as well as less common carotenoids, including α‐bacterioruberin, salinixanthin, and spirilloxanthin derivatives were detected in cell pellets of model organisms belonging to the genera Haloferax, Haloarcula, Halobacterium (Archaea), Salinibacter (Bacteroidetes), and Ectothiorhodospira (Gammaproteobacteria). Direct measurements on such cultures provide fast and reliable identification of pigments. Bacterioruberin was detected as the dominant carotenoid in pellets of cells collected from the saltern crystallizer ponds in Eilat, Israel. Raman analysis of the colored layered microbial communities in a benthic gypsum crust in the saltern evaporation ponds showed signals consistent with the presence of myxoxanthophyll and echinenone carotenoids in the upper orange and dark‐green cyanobacterial layers. Chlorophyll a and phycocyanin expected in the green layer were not detected using the green excitation. Spirilloxanthin dominates the red layer below, inhabited mainly by purple sulfur bacteria. To our best knowledge, this is the first attempt to detect and identify pigments in natural microbial communities consisting of different types of halophilic microorganisms by direct Raman spectrometric measurements using light compact handheld devices. Copyright © 2013 John Wiley & Sons, Ltd.     

空间遥感大气痕量气体临边探测仪设计与研究

为满足空间大气痕量气体探测的迫切需求,设计并研制了一个空间遥感大气痕量气体临边探测仪原型样机.该样机光学系统由离轴抛物面望远镜和改进型Czerny-Turner光谱仪组成,工作波段为380~570 nm.在工作波段内,点列图半径的均方根值均小于9 μm,校正了像散,整个工作波段内同时获得了良好的成像质量.原型样机质量12 kg,体积420×350×200 mm³,空间像元分辨力0.6 km,光谱分辨力0.86 nm,各项指标均满足要求.利用临边探测仪原型样机进行了外场观测试验,外场观测光谱数据与模拟光谱数据进行了比对,二者具有很好的一致性,表明大气痕量气体临边探测仪功能和性能良好,满足大气痕量气体探测的应用要求.     

Elemental Analyzer-Quadrupole MS Coupling—A Low Cost Equipment for the Simultaneous Determination of Carbon/13C and Nitrogen/15N in Isotopically Enriched Soil and Plant Samples

Abstract

Since the end of the 80s elemental analyzer-isotope ratio mass spectrometer connections have been used for the fast, automatic and highly precise determination of carbon and nitrogen content as well as their isotopic composition in one run. But for artificially enriched stable isotopes as tracer in biological processes and since these processes have a high biological variability anyway (e.g. soil processes) the use of these highly precise but also sophisticated and expensive instruments is not required. In this case the use of a quadrupole mass spectrometer connected with an elemental analyzer can offer a low cost alternative. As shown, such coupling is suitable for automatic simultaneous routine analysis of total nitrogen and carbon and their isotopic enrichment (¹⁵N, ¹³C) in plant material and soils. The relative standard deviation for ¹⁵N and ¹³C determination is 2% To meet this precision a careful sample homogenization by grinding is very important. The duration of one measurement is 6–8 min. depending on whether nitrogen alone or both nitrogen and carbon are determined. This enables a high sample throughput.     

Spectrometer for hard X‐ray free‐electron laser based on diffraction focusing

X‐ray free‐electron lasers (XFELs) generate sequences of ultra‐short spatially coherent pulses of X‐ray radiation. A diffraction focusing spectrometer (DFS), which is able to measure the whole energy spectrum of the radiation of a single XFEL pulse with an energy resolution of ΔE/E? 2 × 10^?6, is proposed. This is much better than for most modern X‐ray spectrometers. Such resolution allows one to resolve the fine spectral structure of the XFEL pulse. The effect of diffraction focusing occurs in a single‐crystal plate due to dynamical scattering, and is similar to focusing in a Pendry lens made from a metamaterial with a negative refraction index. Such a spectrometer is easier to operate than those based on bent crystals. It is shown that the DFS can be used in a wide energy range from 5 keV to 20 keV.     

Determining Ppb Mercury Concentrations Using a Spark-Source Mass Spectrometer Sample Changer

Abstract

A probe-type sample changer has been added to a spark-source mass spectrometer enabling the rapid determination of ppb levels of mercury by isotope dilution. The technique has also been used for determining Cd, Hg, and Zr in samples of air, water, and urine.     

Simple,Versatile, Pseudo “Double Beam” Photoacoustic Spectrometer

Abstract

We describe in this paper a “pseudo-double beam” photoacoustic spectrometer using a wide aperture monochromator (F/2) and a very sensitive cell. The double signals required to get the normalized value, i.e., the sample signal and a carbon black reference signal, are obtained by a slow (1.7 Hz) alternating movement of the two cells support, the sample and the reference being alternately placed at the focus point of the beam which is fixed in space and time. The modulation of the light flux is independently ensured by a mechanical chopper. Such an original device associates good performances in resolution (0.7 nm), signal-to-noise ratio (1200 for HO₂O₃ at 450 nm with a 5 nm bandwidth) and normalization in a wide spectral range.     

Reaction Of Nitrides And Oxide With Bath Metals In Gas Analysis In Metals

Abstract

Reactions of two nitrides, an oxide (α-SiaNi, A1N and α-AI2O3) and bath metals (platinum, iron and tin) in graphite capsules were investigated in vacuum fusion analysis by measuring gas extraction curves with a quadrupole mass spectrometer which can simultaneously measure nitrogen and carbon monoxide from the furnace. From the characteristic gas extraction patterns of each bath metals, gas release reaction mechanisms and their temperatures were studied.     

特定化合物碳同位素分析系统中的氧化反应装置的研制

通过对比实验,研制了特定化合物碳同位素在线分析系统中连接气相色谱与同位素比质谱的核心部分——氧化反应装置,包括加热系统、氧化反应系统及接口系统,并以特定化合物的碳同位素分析为例,选用天然气工作标准样品,在600～950℃之间选择8个温度点进行了氧化反应实验,表明其碳同位素测定值(δ13C1,δ13C2,δ13C3)随反应温度升高而逐渐趋于稳定,符合氧化反应过程的一般规律.通过对不同碳数(1≤n≤31)烃类样品(工作标准、国际参考标准、天然气及原油样品)的测试,显示碳同位素值(δ13Calkane)的测试精度优于±(0.2～0.5)‰,满足研究需求,并有效降低了分析成本,具有良好的应用及推广价值.     

A miniature X‐ray emission spectrometer (miniXES) for high‐pressure studies in a diamond anvil cell

Core–shell X‐ray emission spectroscopy (XES) is a valuable complement to X‐ray absorption spectroscopy (XAS) techniques. However, XES in the hard X‐ray regime is much less frequently employed than XAS, often as a consequence of the relative scarcity of XES instrumentation having energy resolutions comparable with the relevant core‐hole lifetimes. To address this, a family of inexpensive and easily operated short‐working‐distance X‐ray emission spectrometers has been developed. The use of computer‐aided design and rapid prototype machining of plastics allows customization for various emission lines having energies from ～3 keV to ～10 keV. The specific instrument described here, based on a coarsely diced approximant of the Johansson optic, is intended to study volume collapse in Pr metal and compounds by observing the pressure dependence of the Pr Lα emission spectrum. The collection solid angle is ～50 msr, roughly equivalent to that of six traditional spherically bent crystal analyzers. The miniature X‐ray emission spectrometer (miniXES) methodology will help encourage the adoption and broad application of high‐resolution XES capabilities at hard X‐ray synchrotron facilities.     

太阳极紫外成像光谱仪光学系统设计

在极紫外波段对太阳进行超光谱成像观测是研究太阳上层大气,日冕中等离子物理特性的重要手段。依据太阳极紫外成像光谱仪的应用,结合国内外极紫外成像光谱仪发展现状,制定了太阳极紫外成像光谱仪的性能指标。通过比较各种光学结构的优缺点,选择望远镜与光谱仪组合的结构。讨论并选择了可用的基本元器件,望远系统采用离轴抛物面反射镜,分光器件为高密度超环面等间距光栅。设计出符合指标的光学系统。最后给出了太阳极紫外成像光谱仪的设计过程、详细参数与结果。光学系统的工作波段为17.0～21.0nm,视场是1 228″×1 024″,空间分辨率达到0.8arcsec.pixel-1,光谱分辨率约为0.001 98nm.pixel-1,系统总长度约为2.8m。