CO的第二泛频(3←0)跃迁谱线线形强度测量研究

CO分子是监测大气污染气体的优异示踪气体,要实现对CO分子实时监控就需要做到对气体浓度的精确快速测量。气体分子浓度测量可以利用测量吸收光谱和谱线线形强度得到,CO的(3←0)泛频谱带是吸收较弱的跃迁波段,利用以干空气为缓冲气体的200μmol/mol的CO混合物,基于稳频的光腔衰荡装置测量了在温度293K、压力13~93kPa下的CO分子R支3条跃迁谱线的吸收光谱。HTP(Hartmann-Tran profile)线形被用来获得这些谱线的线形强度,测量结果的相对标准不确定度优于1%,与国际HITRAN、HITEMP和GEISA光谱数据库比较,相对偏差小于4%。     

Investigation of Environmental Noise in Small Electrical Conductors

Large excess resistance noise has been observed in small conductors surrounded by air. The conductor resistance was found to have a well-defined average power spectral density over the observed frequency range from 10^-4 to 200 Hz and the dependence of the noise was measured as a function of bias current, temperature, temperature coefficient of resistance (TCR), spatial correlation, and state of the surrounding air. In this paper, three different mechanisms were identified that produce the noise. The room-temperature fluctuations were measured and found to have a spectral density nearly proportional to f^-2 over the observed six-order-of-magnitude frequency range. The lowest frequency noise around 10^-4 Hz could be predicted from the measured temperature fluctuations using the TCR. Above 10^-3 Hz and below 1 Hz, enclosing the wire in a box greatly reduces the noise, and placing the wire in a vacuum eliminates the predominant noise. This noise was directly related to the temperature of the conductor, somewhat proportional to the TCR, independent of bias current, and has a correlation length smaller than the specimen size. The highest frequency noise does not depend on the conductor temperature, TCR, or the presence of air. It had a very strong dependence on bias current and had a long spatial correlation. The mechanism that generates this noise is not understood     

Friction and Heat Transfer in the Boundary Layer on a Permeable Surface with Injection of Foreign Gas

A three-parameter (for energy, friction, and vorticity of turbulence) model is used to perform a numerical investigation of the boundary layer on a permeable surface under conditions of injection of a gas whose density and temperature differ from those of the gas of incident flow. The results obtained for the friction coefficient and Stanton number are compared with the available experimental data for the injection of helium, air, carbon dioxide, and Freon into a flow of heated air. It is demonstrated that the density ratio between the gas being injected and the gas of incident flow affects significantly the dependence of friction and heat transfer on the injection parameter.     

Optical switching property of Pd-capped Mg-Ni alloy thin films prepared by magnetron sputtering

Pd-capped Mg-Ni alloy thin films were prepared by magnetron sputtering, on glass substrates, and the dependence of the optical switching property of these films on alloy composition and temperature has been investigated using diluted hydrogen gas and dry air for changing. The transition from the transparent state to the mirror state by dehydrization shows strong dependence on both factors, while the hydrization transition has weak dependence. At higher temperature, the dehydrization is much faster for Mg-rich Mg-Ni thin film whose transition is very slow at room temperature. By using heated air to change from the transparent state to the mirror state, a fast switching can be done for Mg-rich Mg-Ni alloy thin film which has a wide optical modulation range.     

Ice clouds and Asian dust studied with lidar measurements of particle extinction-to-backscatter ratio, particle depolarization, and water-vapor mixing ratio over Tsukuba

The tropospheric particle extinction-to-backscatter ratio, the depolarization ratio, and the water-vapor mixing ratio were measured by use of a Raman lidar and a polarization lidar during the Asian dust seasons in 2001 and 2002 in Tsukuba, Japan. The apparent (not corrected for multiple-scattering effects) extinction-to-backscatter ratios (Sp) showed a dependence on the relative humidity with respect to ice (RHice) obtained from the lidar-derived water-vapor mixing ratio and radiosonde-derived temperature; they were mostly higher than 30 sr in dry air (RHice < 50%), whereas they were mostly lower than 30 sr in ice-supersaturated air (RHice > or = 100%), where the apparent extinction coefficients were larger than 0.036 km(-1). Both regions showed mean particle depolarization ratios of 20%-22%. Comparisons with theoretical calculations and the previous experiments suggest that the observed dependence of Sp on RHice is attributed to the difference in the predominant particles: nonspherical aerosols (mainly the Asian dust) in dry air and cloud particles in ice-supersaturated air.     

Qualitative Determination of the Degree of Doping of Commercial SnO2 Semiconductor Sensors from the Nature of Their Reaction with Hydrogen

The interaction of commercial gas sensors TGS 109, TGS 812, TGS 813, and TGS 815D, manufactured by Figaro, Inc., Japan, with hydrogen has been studied to explain the degree to which they are doped with palladium as a catalyst and the results of those studies are reported here. The method used in the study is based on finding the exponent of the power-law dependence of the sensor conductivity on the hydrogen concentration in the air.     

燃料电池轿车空气辅助系统噪声研究的进展

国内外对燃料电池轿车总体噪声的研究中已指出,空气辅助系统是燃料电池整车的主要噪声源;在对此的分析和介绍中,通过一个实例给出了某燃料电池车空辅系统噪声频谱特性;最后总结了燃料电池车空辅系统噪声研究的方向。     

单泡声致发光中泡内气体含量参数实验研究

液体中的含气量是单泡声致发光相空间的重要参数，对声致发光气泡的运动及发光有重要影响本文给出了一种使用插入式荧光光谱含氧量计测量稳态单泡声致发光的液体中气体含量参数的方法，并对这父键性参数与气泡平衡半径R0和声压Pa的关系进行了具体的研究，再次验证了扩散平衡、化学分解假设理论。     

Polarimetric measurements of long-wave infrared spectral radiance from water

Polarimetric measurements of the thermal infrared spectral radiance from water are reported and are compared with calculations from a recently published model over the spectral range of 600-1600 cm(-1) (6.25-16.67-mum wavelength). In this spectral range, warm water viewed under a dry, clear atmosphere appears vertically polarized by 6-12%. The measured spectral degree of polarization agrees with calculations within the measurement uncertainty (~0.5% polarization in spectral regions with high atmospheric transmittance and 1.5% polarization in spectral regions with low atmospheric transmittance). Uncertainty also arises from temporal changes in water and air temperatures between measurements at orthogonal polarization states, indicating the desirability of simultaneous measurements for both polarization states.     

Ultrasensitive chemiresistors based on electrospun TiO2 nanofibers

Nanostructured semiconducting metal oxides and particularly single nanowire devices offer exceptional gas sensitivity but at the expense of statistical variations and excessive noise levels. In this study TiO2/poly(vinyl acetate) composite nanofiber mats were directly electrospun onto interdigitated Pt electrode arrays, hot pressed at 120 degrees C, and calcined at 450 degrees C. This resulted in a novel multiple nanowire network composed of sheaths of 200-500 nm diameter cores filled with readily gas accessible approximately 10 nm thick single-crystal anatase fibrils. TiO2 nanofiber sensors tested for NO2, in dry air, exhibited exceptional sensitivity showing with, for example, a 833% increase in sensor resistance when exposed to 500 ppb NO2 at 300 degrees C, consistent with a detection limit estimated to be well below 1 ppb. Unusual response patterns were observed at high NO2 concentrations (> 12.5 ppm), consistent with n to p inversion of the surface-trap limited conduction facilitated by the high surface-to-volume ratio of this material.     

Investigation of spermatozoa and seminal plasma by fourier transform infrared spectroscopy

Fourier transform infrared (FT-IR) spectra of human spermatozoa and seminal plasma were recorded and analyzed. The procedure that was established for sample preparation enabled acquisition of reproducible spectra. The parameter I(1087)/I(966) for controlling spectra reproducibility was defined. The assignment of bands was carried out using an empirical approach and the origin of the "sperm specific doublet", the bands at 968 cm(-1) and 981 cm(-1), was determined. The principal component regression (PCR) algorithm was used to define the specific spectral regions correlating to characteristics of spermatozoa, such as concentration, straight-line velocity (VSL), and beat cross frequency (BCF). Then, simple spectral parameters, such as band intensities and band ratios, were tested to determine which one best correlates to characteristics of spermatozoa. The region of the amide I band, between 1700 cm(-1) and 1590 cm(-1), was defined as a specific spectral region that correlates to the concentration of spermatozoa. The parameter that gave the linear dependence to the concentration of spermatozoa was the intensity of the amide I band. For VSL, the bands between 1119 cm(-1) and 943 cm(-1) were defined as the specific spectral region. The relative amount of nucleic acids with respect to proteins showed linear dependence on the straight-line velocity of spermatozoa. BCF showed the best correlation to the bands between 3678 cm(-1) and 2749 cm(-1), which largely represent lipids and proteins. These results suggest that FT-IR spectroscopy can serve as an adjunct to conventional histopathology studies.     

浅谈术语“气体吸湿剂＂

“固体吸湿剂”、“液体吸湿剂”常作为吸湿剂中的两大类型被提及。固体吸湿剂利用吸附原理,对湿空气进行除湿;液体吸湿剂利用吸收原理,使空气达到除湿的效果。而压缩空气作为一种极为干燥的空气,我们称之为“气体吸湿剂”,此空气通过和湿空气混合,实现对湿空气稀释除湿的目的。同时经过压缩空气气体吸湿剂除湿后的空气可以与蒸发冷却技术相结合应用于空调中,大大提高蒸发冷却降温的效率。另外,在我国西北等干燥地区大气中存在着一种经过大自然除湿后的天然干燥空气一千空气,我们可充分利用这种气体吸湿剂,直接送入建筑物内消除室内的湿负荷,大大降低人工制冷除湿的能耗,同时充分利用“干空气能”,达到尽量采用蒸发冷却天然冷源降温的效果,从而实现建筑低能耗的目的。“气体吸湿剂”是一种新的吸湿剂概念,为此,本文对术语“气体吸湿剂”进行了初步的探讨。     

Emission characteristics of coal combustion in different O2/N2, O2/CO2 and O2/RFG atmosphere

This study investigates the emission characteristics of CO(2), SO(2) and NOx in the flue gas of coal combustion by varying the compositions and concentrations of feed gas (O(2)/CO(2)/N(2)) and the ratios of recycled flue gas. The differences between O(2)/recycled flue gas (O(2)/RFG) combustion and general air combustion are also discussed. Experimental results indicate that the maximum concentration of CO(2) in O(2)/CO(2) combustion system is 95% as the feed gas is 30% O(2)/70% CO(2). The average concentration of CO(2) in the flue gas of O(2)/CO(2) coal combustion system is higher than 90% and much higher than that of O(2)/N(2) coal combustion system. This high concentration of CO(2) is beneficial for the separation of CO(2) from the flue gas by adsorption or absorption technologies. The maximum concentration of CO(2) in O(2)/N(2) combustion system is only 34% at the feed gas 50% O(2)/50% N(2), the concentration of CO(2) is increased with the concentration of O(2) in feed gas. By O(2)/CO(2) combustion technology, higher concentration of SO(2) is produced as the feed gas is 30% O(2)/70% CO(2) or 40% O(2)/60% CO(2), while higher concentration of NOx is produced as the feed gas is 20% O(2)/80% CO(2) or 50% O(2)/50% CO(2). The mass flow rates of CO(2), SO(2) and NOx in the flue gas are all increased with the ratio of recycled flue gas except for the feed gas 20% O(2)/80% CO(2). The enhanced mass flow rates of air pollutants in such O(2)/RFG combustion system are also beneficial for improving the control efficiencies of air pollution control devices. By O(2)/N(2) combustion technology, higher concentrations of SO(2) and NOx are produced as the feed gas is 21% O(2)/79% N(2). The results also indicate that the formation of NOx in general air combustion system is higher than that in O(2)/RFG or O(2)/CO(2) combustion system.     

Band-integrated infrared absorptance of low-molecular-weight paraffin hydrocarbons at high temperatures

The spectral absorptance of the 3.4-mum band of methane, ethane, propane, and butane has been measured with a Fourier transform infrared spectrometer over a range of temperatures from 296 to 900 K. The measurements were made at a 4-cm(-1) resolution and integrated over the entire band to give the total absorptance. The total absorptance is found to behave in such a way that it can be correlated by a combination of algebraic expressions that depend on the gas temperature and concentration. Average discrepancies between the correlations and the measurements are less than 4%, with maximum differences of no greater than 17%. In addition, the correlations presented here for methane are shown to be in good agreement with established models. Expressions given for the integrated intensity of each gas show an inverse dependence on temperature, reflecting the associated change in density.     

Narrow-linewidth vertical-cavity surface-emitting lasers for oxygen detection

The use of vertical-cavity surface-emitting lasers (VCSEL's) for optical detection of atmospheric oxygen is described. The VCSEL's were custom designed for single-mode emission in the 763-nm wavelength range, with low noise and narrow optical linewidth. Using standard wavelength modulation spectroscopy and a second-harmonic detection scheme with a 1-m air path, we determined an oxygen concentration resolution of 0.2%. Because of its small size, low power dissipation, and good tunability characteristics, the VCSEL promises to be an attractive light source for use in compact, low-cost optical sensor microsystems for trace gas detection.     

Dependence of the channel electron multiplier noise spectral functions on the parameters of its operation

The channel electron multiplier (CEM) current flicker noise was examined for different parameters of its operation. In particular, the dependence of CEM power spectral density function on its output current value has been verified. Also the dependence of the CEM power spectral density function on the input electron energy was investigated.     

Particle-phase dry deposition and air-soil gas exchange of polycyclic aromatic hydrocarbons (PAHs) in Izmir, Turkey

Ambient air and dry deposition samples were collected at suburban and urban sites in Izmir, Turkey. Atmospheric total (particle+gas) ∑(14)PAHs concentrations were 36±39 and 144±163 ng m(-3) for suburban and urban sites, respectively. Phenanthrene was the most abundant compound at all sites, and all samples were dominated by low molecular weight PAHs. Average particulate ∑(14)PAH dry deposition fluxes were 8160±5024 and 4286±2782 ng m(-2) day(-1) and overall average particulate dry deposition velocities were 1.5±2.4 and 1.0±2.3 cm s(-1) for suburban and urban sites, respectively. Soil samples were collected at suburban site. Average soil concentration for ∑(14)PAH was 55.9±14.4 ng g(-1) dry weight. Calculated gas-phase air-soil exchange fluxes indicated that fluorene, phenanthrene, anthracene, and carbazole were deposited to soil in winter while they were volatilized in summer. Other compounds (fluoranthene-benzo[g,h,i]perylene) were deposited to soil in both periods. Annual average fluxes of PAHs representing soil to air (i.e., gas volatilization) and air to soil transfer (i.e., gas absorption, dry deposition, and wet deposition) processes were also compared. All processes were comparable for Σ(14)PAHs however their input was dominated by gas absorption. Gas absorption dominated for lower molecular weight PAHs, however dry deposition dominated for higher molecular weight PAHs. The results have suggested that for fluorene, soil and air may be approaching a steady state condition. For the remaining compounds, there was a net accumulation into the soil.     

大型空分设备气体放空的噪声控制与治理

文章简介了空分设备气体放空时产生的噪声对周围环境的污染和伤害,并对放空气体噪声的控制与治理进行了分析对比;提出大型空分设备,特别是内压缩流程的空分设备,大流量低、中、高压气体放空,应采用消声塔集中排放,有效控制和治理气体放空噪声。     

大型空分设备气体放空的噪声控制与治理

文章简介了空分设备气体放空时产生的噪声对周围环境的污染和伤害，并对放空气体噪声的控制与治理进行了分析对比；提出大型空分设备，特别是内压缩流程的空分设备，大流量低、中、高压气体放空，应采用消声塔集中排放，有效控制和治理气体放空噪声。     

Solid-state stability studies of faropenem based on chromatography,spectroscopy and theoretical analysis

Aim: The purpose of this study was to investigate the stability of faropenem in solid state.

Results: The kinetic and thermodynamic parameters of degradation of faropenem were studied using an RP-HPLC method while the changes of spectral properties were investigated using derivative UV and FT-IR. Quantum-chemical calculations, based on the density functional theory, were carried out to support the estimation of the intra-ring stresses of faropenem and for theoretical interpretation of the spectra. The degradation of faropenem was a first-order reaction depending on the substrate concentration at an increased relative humidity and in dry air. The dependence ln k = f(1/T) became the ln k?=?(2.03?±?3.22)?×?10⁴–(9761?±?3052)(1/T) in dry air and ln k?=?(1.25?±?0.22)?×?10⁵–(9004?±?3479)(1/T?) at 90.0% RH. The thermodynamic parameters E_a, ΔH^≠a, and ΔS^≠a of the degradation of faropenem were calculated. The dependence ln k?=?f(RH%) assumed the form ln k?=?(7.58?±?1.88)?×?10^?2 (RH%) – (5.90?±?3.90)?×?10^?8.

Conclusions: Stability studies of faropenem showed that the fusion of β-lactam and thiazolidine rings reduces the intra-ring stress, leading to a lower susceptibility to degradation in dry air and at increased RH.