一种自适应层进式Savitzky‐Golay光谱滤波算法及其应用

可调谐半导体激光吸收光谱技术（TDLAS）利用半导体激光器的可调谐和窄线宽特性，通过选择特定气体的单条吸收线，排除其余气体的干扰，可以实现高精度、高选择性的气体浓度测量，在气体浓度检测系统中具有广泛的应用前景。在不同的应用条件和环境下，需要解决相应的硬件和数据处理方面的技术问题。主要研究TDLAS技术机动车尾气CO组分浓度遥测系统中的光谱数据处理问题，该系统利用路面漫反射回波信号遥测行驶中的机动车尾气CO组分浓度。由于激光扫描光谱回波信号受到漫反射面情况变化、空气环境变化、尾气湍流影响等因素影响，探测器收集到的信号不仅较弱同时也夹杂着多种噪声, 即测量光路信噪比较差, 故提出一种自适应层进式Savitzky-Golay(S-G)平滑滤波算法，实现了对光谱进行滤波处理从而更加准确地反演CO浓度。S-G滤波算法因其原理简单、功能强大、只需设置两个参数（窗口大小、拟合阶数）等优点，已广泛应用于光谱处理。如何正确设置S-G算法参数使滤波效果在去噪不足和过度滤波之间找到平衡点，是该滤波算法应用的一大难题。设计的检测系统中，测量光路光谱信号为非平稳信号，噪声和有效信号幅度时变，最佳窗口大小和多项式阶数随信号动态而变化，且变化区间较大，使用固定参数的S-G滤波器难以达到最佳效果。提出的自适应层进式S-G平滑滤波算法，通过逐层将测量光路光谱信号经过S-G滤波后，与参考光路的光谱信号设置的参考段比对信号相关系数和信号一阶导相关系数的和，以自适应得到逐层最优参数。通过对信噪比从9.81～29.77的10组不同带噪光谱分析验证了该算法的有效性，自适应层进式S-G算法能较好地去除噪声并还原带噪信号所携带的待测气体浓度信息，与带噪光谱对比，吸收光谱峰值最大误差由25.152%降至5.917%，积分吸光度最大误差由18.1%降至3.9%。在实现的系统中，使用自适应层进式S-G算法对测量光路进行滤波处理，并对不同车型、不同排量、燃烧不同油品的机动车在怠速和缓速通过(5 km·h-1)系统时其排放的CO浓度进行实时在线监测。     

Hydrothermal synthesis of ZnO whiskers from ɛ-Zn(OH)2 in NaOH/Na2SO4 solution

The influence of Na₂SO₄ on the formation of ZnO whiskers was investigated in this paper. ZnO whiskers with aspect ratios of up to 50 were synthesized by dissolving ɛ-Zn(OH)₂ precursor in NaOH/Na₂SO₄ solution at room temperature, followed by aging of the resulting solution at 140 °C for 6 h. Fourier transform infrared spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy analyses revealed that SO₄²⁻ ions were primarily adsorbed on the (1 0 0) plane of the ZnO whiskers via an outer-sphere complex configuration (OH···O), thereby promoting the one-dimensional growth of ZnO whiskers along the c-axis.     

EAST极紫外空间分辨光谱分析软件的开发

基于Matlab软件的图形用户界面开发环境(GUIDE)设计开发了一套交互式界面，可以自动读取、解析原始数据，开展波长标定，将谱强度与谱仪系统空间测量位置以及EAST实验放电时间等信息相关联，从而快速、便捷地计算杂质离子发出的线光谱强度的空间分布并绘图。该空间分辨光谱分析软件的开发和应用大大提高了谱仪数据处理和分析的便捷性和效率，保证了放电期间数据处理的准实时性。     

Optimization of a transmit/receive surface coil for squirrel monkey spinal cord imaging

MR Imaging the spinal cord of non-human primates (NHP), such as squirrel monkey, is important since the injuries in NHP resemble those that afflict human spinal cords. Our previous studies have reported a multi-parametric MRI protocol, including functional MRI, diffusion tensor imaging, quantitative magnetization transfer and chemical exchange saturation transfer, which allows non-invasive detection and monitoring of injury-associated structural, functional and molecular changes over time. High signal-to-noise ratio (SNR) is critical for obtaining high-resolution images and robust estimates of MRI parameters. In this work, we describe our construction and use of a single channel coil designed to maximize the SNR for imaging the squirrel monkey cervical spinal cord in a 21 cm bore magnet at 9.4 T. We first numerically optimized the coil dimension of a single loop coil and then evaluated the benefits of a quadrature design. We then built an optimized coil based on the simulation results and compared its SNR performance with a non-optimized single coil in both phantoms and in vivo.     

A Lewis acid-catalyzed tandem reaction enabling 2-arylglycerol derivative as a versatile 1,3-biselectrophile for the synthesis of 4H-chromenes and 2-pyridinones

Acid-catalyzed tandem reactions were established by employing a novel class of 2-arylglycerol derivative,5-aryl-1,3-dioxan-5-ol, as versatile 1,3-biselectrophile. In the reactions, 5-aryl-1,3-dioxan-5-ol works like atropaldehydes or 2-aryl malondialdehydes, and can react with 2-naphthols and β-keto amides, allowing the synthesis of 4H-chromenes and 5-aryl-2-pyridinones. High yields, good functional group tolerance,broad substrate scope and simple reaction operation make this protocol attractive.     

Noble metal nanoparticles meet molecular cages: A tale of integration and synergy

Noble metal nanoparticles attract growing interest owing to their high surface-to-volume ratio and unique optical, electric and catalytic properties. Fine-tuning these properties and broadening potential applications can be envisaged if nanoparticles are coupled to supramolecular cages that afford a highly tailorable inner environment as well as rich endo-/exo-functionalization. Due to rich chemical/physical properties of cages, integration of multiple host-guest interactions in confined cavities through endo-molecular design has been achieved. Such cages provide ideal confined templates for size-controlled synthesis of ultrafine nanoparticles with superior catalytic activities. Moreover, exo-functionalization of cages offers huge opportunities to couple with nanoparticles, generating cage-nanoparticle hybrids or hierarchical assemblies that combine merits of both. The present review provides recent advances in cage-mediated nanoparticle systems with synergistic effects and integrated functions, and demonstrates their applications in catalysis, sensing, chiral amplification, plasmonic switches, imaging and cell therapy. Finally, we highlight key challenges and identify emerging directions in the coming years.     

A Polarized Gel Electrolyte for Wide-Temperature Flexible Zinc-Air Batteries

The development of flexible zinc-air batteries (FZABs) has attracted broad attention in the field of wearable electronic devices. Gel electrolyte is one of the most important components in FZABs, which is urgent to be optimized to match with Zn anode and adapt to severe climates. In this work, a polarized gel electrolyte of polyacrylamide-sodium citric (PAM-SC) is designed for FZABs, in which the SC molecules contain large amount of polarized −COO⁻ functional groups. The polarized −COO⁻ groups can form an electrical field between gel electrolyte and Zn anode to suppress Zn dendrite growth. Besides, the −COO⁻ groups in PAM-SC can fix H₂O molecules, which prevents water from freezing and evaporating. The polarized PAM-SC hydrogel delivers a high ionic conductivity of 324.68 mS cm⁻¹ and water retention of 96.85 % after being exposed for 96 h. FZABs with the PAM-SC gel electrolyte exhibit long cycling life of 700 cycles at −40 °C, showing the application prospect under extreme conditions.     

The effect of the alkyl chain length of the tetraalkylammonium cation on CO2 electroreduction in an aprotic medium

The effect of tetraalkylammonium cation (TAA⁺) chain length on CO₂ electroreduction is investigated on an Ag electrode in a DMF solution. Linear sweep voltammetric (LSV) studies show that the onset potentials of CO₂ reduction move to increasingly negative potentials upon increasing the alkyl chain length of the tetraalkylammonium cation of the supporting electrolyte. Density functional theory (DFT) computations indicate that the onset potential of CO₂ reduction is dependent on the strength of ion pairing between TAA⁺ cation and the electrogenerated CO₂^.−. CO₂ disturbance experiments reveal that the peak current of CO₂ reduction is determined by the quantity of TAA⁺ cation adsorbed on the Ag surface.     

Addendum to “Volumetric properties of binary liquid-phase mixture of (water + glycerol) at temperatures of (278.15 to 323.15) K and pressures of (0.1 to 100) MPa” [J. Chem. Thermodyn. 79 (2014) 135–158]: Effect of pressure on excess thermodynamic characteristics of mixture water + glycerol

Experimentally determined volumetric properties of the liquid binary mixture of {water (1) + glycerol (2)} were processed to calculate the changes of the following thermodynamic parameters with pressure: excess molar Gibbs free energy, ${\mathrm{\Delta }}_{P_o\to P}{G}_m^E$, excess molar entropy, ${\mathrm{\Delta }}_{P_o\to P}{S}_m^E$, excess molar enthalpy, ${\mathrm{\Delta }}_{P_o\to P}{H}_m^E$, as well as the enthalpy of mixing of water and glycerol, $H_m^E$, at 100 MPa. The mixing enthalpies of water and glycerol, $H_m^E$, became more exothermic with pressure increasing at all temperatures studied.