High sensitivity CW-cavity ring down spectroscopy of water in the region of the 1.5 μm atmospheric window

The absorption spectrum of natural water vapour around 1.5 μm has been recorded with a typical sensitivity of 5 × 10⁻¹⁰ cm⁻¹ by using a CW-cavity ring down spectroscopy set up based on fibred DFB lasers. A series of 31 DFB lasers has allowed a full coverage of the 6130.8-6748.5 cm⁻¹ (1.63-1.48 μm) region corresponding to the H transparency band of the atmosphere. The line parameters (wavenumber and intensity) of a total of 5190 lines, including 4247 lines of water vapor, were derived by a one by one fit of the lines to a Voigt profile. Different isotopologues of water (H₂¹⁶O, H₂¹⁸O, H₂¹⁷O, and HD¹⁶O) present in natural abundance in the sample contribute to the spectrum. For the main isotopologue, H₂¹⁶O, 2130 lines were measured with line intensities as weak as 10⁻²⁹ cm/molecule while only 926 lines (including a proportion of 30% inaccurate calculated lines) with a minimum intensity of 3 × 10⁻²⁷ cm/molecule are provided by the HITRAN and GEISA databases. Our comparison in the whole 5750-7965 cm⁻¹ region, has also evidenced that an error in the process of conversion of the intensity units from cm⁻²/atm to cm⁻¹/(molecule × cm⁻²) at 296 K, has led to H₂¹⁶O line intensities values listed in the HITRAN-2000 database, systematically 8 % below the original FTS values. The rovibrational assignment was performed on the basis of the ab initio calculations by Schwenke and Partridge with a subsequent refinement and validation using the Ritz combination principle together with all previously measured water transitions relevant to this study. This procedure allowed determining 172, 139, 71, and 115 new energy levels for the H₂¹⁶O, H₂¹⁸O, H₂¹⁷O, and HD¹⁶O isotopologues, respectively. The results are compared with the available databases and discussed in regard of previous investigations by Fourier transform spectroscopy. The spectrum analysis has showed that most of the transitions which cannot be assigned to water are very weak and are due to impurities such as carbon dioxide and ammonia, leaving only about 3% of the observed transitions unassigned. The interest of a detailed knowledge of water absorption for trace detectors developed in the 1.5 μm range is underlined: for instance HDO contributes significantly to the considered spectrum while no HDO line parameters are provided by the HITRAN database.     

Three-dimensional hydrogen-bond geometry and probability information from a crystal survey

Summary An extensive crystal survey of the Cambridge Structural Database has been carried out to provide hydrogen-bond data for use in drug-design strategies. Previous crystal surveys have generated 1D frequency distributions of hydrogen-bond distances and angles, which are not sufficient to model the hydrogen bond as a ligand-receptor interaction. For each hydrogen-bonding group of interest to the drug designer, geometric hydrogen-bond criteria have been derived. The 3D distribution of complementary atoms about each hydrogen-bonding group has been ascertained by dividing the space about each group into bins of equal volume and counting the number of observed hydrogen-bonding contacts in each bin. Finally, the propensity of each group to form a hydrogen bond has been calculated. Together, these data can be used to predict the potential site points with which a ligand could interact and there-fore could be used in molecular-similarity studies, pharmacophore query searching of databases, or de novo design algorithms.     

一种有机质谱谱图的库检索新算法

一种有机质谱谱图的库检索新算法律祥俊，林少凡，张金碚，张法义（南开大学中心实验室，天津，３０００７１）关键词检索，算法，质谱，数据库利用计算机匹配技术识别有机质谱谱图中的库检索方法仅需用低分辨质谱图即可识别未知化合物，似为最成功的方法［１～３］．质谱...     

TTRMDB: A database for structural and functional analysis on the impact of SNPs over transthyretin (TTR) using bioinformatic tools

Hereditary Transthyretin-associated amyloidosis (ATTR) is an autosomal dominant protein-folding disorder with adult-onset caused by mutation of transthyretin (TTR). TTR is characterized by extracellular deposition of amyloid, leading to loss of autonomy and finally, death. More than 100 distinct mutations in TTR gene have been reported from variable age of onset, clinical expression and penetrance data. Besides, the cure for the disease remains still obscure. Further, the prioritizing of mutations concerning the characteristic features governing the stability and pathogenicity of TTR mutant proteins remains unanswered, to date and thus, a complex state of study for researchers. Herein, we provide a full report encompassing the effects of every reported mutant model of TTR protein about the stability, functionality and pathogenicity using various computational tools. In addition, the results obtained from our study were used to create TTRMDB (Transthyretin mutant database), which could be easy access to researchers at http://vit.ac.in/ttrmdb.     

基于ARM11的热力站远程水质监控系统设计

为实现对循环水水质的远程监测,设计并开发了一种基于嵌入式技术的热力站远程水质监测系统的监测终端。监测终端由水质传感器、GPRS模块、通信转换模块及嵌入式开发板组成。嵌入式开发板以ARM11系列的Tiny6410为硬件基础,并嵌入WinCE系统作为软件平台,同时加入SQLite数据库以实现将水质传感器采集到的氯离子、PH值、溶解氧等参数的本地存储、查询及图表显示。最后监测终端通过GPRS模块与数据中心建立无线连接,接收数据中心的配置命令,并将现场测得数据发送到远端数据中心。调试结果表明：远程监测终端实现了循环水水质远程监测的功能要求,对于实现水质自动化监测具有一定的理论意义和实用价值。     

Empirical line parameters of methane in the 1.63–1.48 μm transparency window by high sensitivity Cavity Ring Down Spectroscopy

The positions and intensities of methane in the 1.58 μm transparency window have been measured by high sensitivity Cavity Ring Down Spectroscopy at room temperature. The achieved sensitivity allowed measuring intensities as small as 3 × 10⁻²⁹ cm/molecule i.e. three orders of magnitude smaller than the intensity cut off of the HITRAN line list of methane. The complete list contains a total of 16,149 transitions between 6165 and 6750 cm⁻¹. Their intensity values vary over six orders of magnitude from 1.6 × 10⁻²⁹ to 2.5 × 10⁻²³ cm/molecule. Transitions due to CH₃D in “natural” abundance in our methane sample were identified using a new spectrum of CH₃D recorded separately with a Fourier Transform spectrometer. From simulations of the CH₃D and methane spectra at low resolution, the CH₃D isotopologue has be found to contribute by up to 30% of the absorption near 1.58 μm.     

利用HITRAN资料研究黑碳和沙尘气溶胶粒子的光学特性

在IDL程序语言中实现Mie理论的数值算法,利用HITRAN资料提供的气溶胶粒子复折射指数,计算分析了沙尘、黑炭2种气溶胶粒子在不同半径（1μm,2.5μm和10μm）时,对波长为400nm和860nm光的散射效率以及散射相函数矩阵元素。结果表明：黑炭与沙尘有明显的光学性质差别,沙尘粒子不仅散射效率大于黑碳,而且后向散射比黑碳粒子强。 2种粒子对400 nm和860 nm太阳光的偏振也不同,可以利用此特性鉴别这2种气溶胶。     

基于组态软件和多串口通讯的真空检漏监测系统设计与开发

许 婕,蔡立君,卢 勇,罗 山,张 龙,田培红     

Temperature dependence of the absorption spectrum of CH4 by high resolution spectroscopy at 81 K: (I) The region of the 2ν3 band at 1.66 μm

In a recent contribution, (Gao B, Kassi S, Campargue A. Empirical low energy values for methane transitions in the 5852-6181 cm⁻¹ region by absorption spectroscopy at 81 K. J Mol Spectrosc 2009;253:55-63.), the low energy values of methane transitions between 1.71 and 1.62 μm were derived from the variation of the line intensities between 296 and 81 K. The line intensities at 81 K were retrieved from the high resolution absorption spectrum of methane recorded at liquid nitrogen temperature by direct absorption spectroscopy using a cryogenic cell and a series of distributed feed back (DFB) diode lasers. For the line intensities at 296 K, the values provided by the HITRAN database were used. As a consequence of the relatively high intensity cut off (4×10⁻²⁴ cm/molecule) of the HITRAN line list in the considered region, the lower energy values were derived for only 845 of the 2187 transitions measured at 81 K. In the present work, our line list was extended by the retrieval of many weak line intensities leading to a set of 3251 transitions. The minimum value of the measured line intensities (at 81 K) is on the order of 10⁻²⁶ cm/molecule. In relation with the project “Greenhouse Gases Observing Satellite” (GOSAT), a much more complete line list for CH₄ at 296 K has become available (intensity cut off of 4×10⁻²⁶ cm/molecule). By applying the two temperature method to our line intensities at 81 K and GOSAT intensities at 296 K, the lower energy values of 2297 transitions could be derived. These transitions represent 99.1% and 90.8% of the total absorbance in the region, at 81 and 296 K respectively. This line list provided as Supplementary Material allows then accounting for the temperature dependence of CH₄ absorption below 300 K. The investigated spectral range is dominated by the 2ν₃ band near 6005 cm⁻¹ which is of particular interest for atmospheric retrievals. The factor 2 narrowing of the Doppler linewidth from room temperature down to 81 K has allowed the resolution of a number of 2ν₃ multiplets and improving the line intensity retrievals. A detailed comparison with GOSAT and HITRAN line lists has revealed a number of possible improvements.