Using high-power lasers for detection of elastic photon-photon scattering

The properties of four-wave interaction via the nonlinear quantum vacuum is investigated. The effect of the quantum vacuum is to generate photons with new frequencies and wave vectors, due to elastic photon-photon scattering. An expression for the number of generated photons is derived, and using state-of-the-art laser data it is found that the number of photons can reach detectable levels. In particular, the prospect of using the high-repetition Astra Gemini system at the Rutherford Appleton Laboratory is discussed. The problem of noise sources is reviewed, and it is found that the noise level can be reduced well below the signal level. Thus, detection of elastic photon-photon scattering may for the first time be achieved.     

非常温溶液除湿自主再生空调系统性能分析

提出一种新型的将溶液除湿与热泵相结合的温湿度独立处理空调系统,该系统使用低温、低浓度的除湿溶液,在任何工况下冷凝热都能满足溶液再生的需求。建立了整个系统的数学模型,研究系统自身参数变化(溶液温度、浓度)和环境参数变化(空气温度、湿度)对系统性能的影响;并对系统应对高温、高湿度环境的调整方法进行了分析。结果表明,在夏季典型工况下,除湿溶液的理想温度为17~19℃、相应的质量浓度为25.39%~26.88%;系统具有较高的能效,并且能够在高温潮湿地区发挥其节能潜力。     

Radiation-driven hydrodynamics of high- hohlraums on the national ignition facility

The first hohlraum experiments on the National Ignition Facility (NIF) using the initial four laser beams tested radiation temperature limits imposed by plasma filling. For a variety of hohlraum sizes and pulse lengths, the measured x-ray flux shows signatures of filling that coincide with hard x-ray emission from plasma streaming out of the hohlraum. These observations agree with hydrodynamic simulations and with an analytical model that includes hydrodynamic and coronal radiative losses. The modeling predicts radiation temperature limits with full NIF (1.8 MJ), greater, and of longer duration than required for ignition hohlraums.     

Quasiparticle approach to the modulational instability of drift waves coupling to zonal flows

The interaction between broadband drift mode turbulence and zonal flows has been studied through the wave-kinetic approach. Simulations have been conducted in which a particle-in-cell representation is used for the quasiparticles, while a fluid model is employed for the plasma. The interactions have been studied in a plasma edge configuration which has applications in both tokamak physics and magnetopause boundary layer studies. Simulation results show the development of a zonal flow through the modulational instability of the drift wave distribution, as well as the existence of solitary zonal flow structures about an ion gyroradius wide, drifting towards steeper relative density gradients.     

近红外光谱相关系数法用于快速检测药品的质量

对近红外光谱相关系数法检测药品质量变化的效果进行了研究,并考察了相关系数方法对同一品种药品来自不同厂家生产的样品的区分能力进行了计算,还研究了在不同仪器上、由不同人员测定光谱时相关系数方法的识别能力。本文还对计算相关系数时的光谱预处理方法和谱段等参数进行了探讨,提供了建议性的参数条件,为近红外光谱相关系数方法用于药品质量快速分析提供参考。     

Frequency discrimination of complex tones; assessing the role of component resolvability and temporal fine structure

Thresholds for discriminating the fundamental frequency (FO) of a complex tone, FODLs, are small when low harmonics are present, but increase when the number of the lowest harmonic, N, is above eight. To assess whether the relatively small FODLs for N in the range 8-10 are based on (partly) resolved harmonics or on temporal fine structure information, FODLs were measured as a function of N for tones with three successive harmonics which were added either in cosine or alternating phase. The center frequency was 2000 Hz, and N was varied by changing the mean FO. A background noise was used to mask combination tones. The value of FO was roved across trials to force subjects to make within-trial comparisons. N was roved by +/- 1 for every stimulus, to prevent subjects from using excitation pattern cues. FODLs were not influenced by component phase for N= 6 or 7, but were smaller for cosine than for alternating phase once N exceeded 7, suggesting that temporal fine structure plays a role in this range. When the center frequency was increased to 5000 Hz, performance was much worse for low N, suggesting that phase locking is important for obtaining low FODLs with resolved harmonics.     

吸光度比值-导数光谱法同时测定铜(Ⅱ)和铬(Ⅲ)的研究

提出了运用吸光度比值-导数光谱法同时测定Cr(Ⅲ)与Cu(Ⅱ)含量的新方法。在pH 5.7的HAc-NaAc的缓冲溶液中,Cr3+,Cu2+与铬天青S(CAS)和溴化十六烷基三甲胺(CTMAB)可分别形成蓝色三元络合物。其摩尔吸光系数分别为2.52×105 L·mol-1·cm-1和1.01×105 L·mol-1·cm-1。Cu2+和Cr3+的浓度分别在0.08～1.2 μg·mL-1和0.05～0.52 μg·mL-1范围内符合比尔定律,其检测限分别为0.014和0.013 μg·mL-1。此方法应用于环境水中Cr(Ⅲ),Cu(Ⅱ)的同时测定,取得了满意的结果。     

维生素A酸在银溶胶液中的表面增强拉曼散射光谱

将水中不溶的药物维生素A酸(VAA)溶于氯仿中,然后与银溶胶液混合,振摇,取静置分层后的上层溶胶液测定表面增强拉曼光谱,氯仿在银溶胶中无表面增强效应,不干扰维生素A酸的测定。与固体粉末拉曼光谱相比较,对光谱峰归属进行了解释。通过分析CO伸缩振动带和ν(COO)振动峰明显增强的现象,讨论了维生素A酸分子在银颗粒表面可能的吸附取向,并推断维生素A酸在银表面的吸附发生在COO-基团。以维生素A酸表面增强拉曼光谱在1583cm-1处的峰强度对浓度进行线性回归,求得线性回归方程Y=10×108+95585,在10×10-6～50×10-5mol·L-1范围呈良好的线性关系,最小检测限为10×10-7mol·L-1。结果表明,维生素A酸表面增强拉曼光谱峰数量少,灵敏度高,是定量分析痕量维生素A酸的很好方法。