Photoirradiation of polycyclic aromatic hydrocarbon diones by UVA light leading to lipid peroxidation

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous genotoxic environmental pollutants and potentially pose a health risk to humans. In most if not all cases, PAHs in the environment can be oxidized into their corresponding PAH-diones. This process is considered a detoxification pathway with regard to tumorigenicity. Nevertheless, photo-induced toxicological activity of PAH-diones has not been systematically investigated. In this study, we show that 27 potential environmental PAH-diones induced lipid peroxidation, in a dose (light) response manner, when irradiated with UVA at 7 and 21 J cm⁻². Photoirradiation in the presence of sodium azide, deuterated methanol, or superoxide dismutase revealed that lipid peroxidation is mediated by reactive oxygen species. Electron spin resonance (ESR) spin trapping studies supported this observation. These results suggest that UVA photoirradiation of PAH-diones generates reactive oxygen species and induces lipid peroxidation.     

大跨人行过街天桥利用MTMD减振控制的理论分析

大跨人行天桥的自振频率通常比较低,与人行走时的频率接近,因此行人通过天桥时容易产生竖向共振,影响天桥的正常使用。本文研究多重调谐质量阻尼(MTMD)系统对大跨人行过街天桥竖向振动的控制作用,首先建立起天桥-MTMD系统的分析模型,推导出系统的传递函数及动力放大系数的数学表达式,继而分析了TMD的数量、阻尼比和频带宽等参数对结构的动力放大系数的影响,为实际工程结构设计MTMD减振系统时提供参考。以沈阳某大跨人行天桥为例,进行MTMD优化设置后,能有效减小天桥的受迫振动和自由振动,从而将振动控制在人体的舒适度范围之内。     

GJB4．7—83“舰船电子设备环境试验振动试验”和MIL—STD-167—1A“舰船设备的机械振动（Ⅰ类-环境振动）”的分析与对比

设备的振动试验不仅涉及到设备共振频率（或响应极值频率）和设备功能或结构完整性受影响的非响应极值频率（如任何出现结构、功能、机械或电气异常的频率）的确定，还有耐久试验频率及适当试验时间的选择。本文在对国军标GIB4．7-83誓舰船电子设备环境试验振动试验”与美军标MILSTD-167—1A“舰船设备的机械振动（Ⅰ类-环境振动）”比较和分析的基础上，提出了GJB47—83修订的必要性。     

The bioeffects of extremely weak power-frequency alternating magnetic fields

We report the results of a study of the influence of extremely-weak alternating magnetic fields (EW AMF) directed co-linearly to the static Earth’s magnetic field on the rate of regeneration in planarians and also on the rate of gravitropic response in the stem segments of flax. In particular we obtained the data on the dependence of the value of bioeffects on the amplitude (at fixed 60 Hz—frequency) and on the frequency (at fixed 1.6 μT—amplitude) of the alternating component. Our data show unambiguously that EW AMF substantially affect the properties of the biosystems. The experimental data may be approximated by the theoretical expression following directly from a general formula, derived in the theory of magnetic parametric resonance. Our data indicate that the nuclear spins of hydrogen atoms serve as the primary targets for the action of the EW AMF on the biosystems. The values of bioeffects of combined magnetic fields with extremely weak alternating component are completely determined by the parameter , where γ = 42.578 Hz/μT—gyromagnetic ratio of the nuclear spins of hydrogen atoms, and and f correspond to magnetic induction and frequency of the alternating magnetic component. The dependence of bioeffect’s value on —parameter is polyextremal: well expressed maxima are observed at and minor maxima at . The bioeffects are absent at , 3.8, 5.3, 6.7. At the values of the bioeffect changes its sign—activation of planarian’s regeneration starts to be replaced by its inhibition. The inhibition takes place for the range of the amplitudes from 10 to 140 μT. The observed change in the sign of the effect may result to the prevalence of the effects caused by the induction of the alternating currents in the test-system at relatively high —amplitudes. These results provide the basis for planning of the epidemiological studies and interpretation of the corresponding results.     

基于随机森林的光散射法传感器微站PM2.5监测值的校正方法研究

光散射法传感器微站以其体积小、反应迅速、成本低等优点,已成为城市PM_2.5规模化移动监测的新选择.由于其标准与传统标准台站不同,必须对这类微站的监测数据进行准确地校正.本研究利用2021年06月—2022年02月武汉市江夏区标准台站及同期传感器微站监测数据,探讨传感器微站监测误差与温度、相对湿度的关系,并通过随机森林回归（Random Forest Regressor,RFR）校正传感器微站PM_2.5监测数据.对比单一RFR模型、按气象因素分类后RFR模型、“小波去噪+RFR”组合模型、“加权滑动平均去噪+RFR”组合模型校正效果,结果表明：RFR模型和分类后RFR模型均出现泛化能力差的问题,不能满足校正需求;“小波去噪+RFR”组合模型、“加权滑动平均去噪+RFR”组合模型平均绝对误差分别为8.77 μg·m^-3和4.78 μg·m^-3,平均相对误差分别为40.80%和18.13%.去噪组合模型能满足校正需求,且“加权滑动平均+RFR”组合模型校正效果明显优于“小波去噪+RFR”组合模型.研究结果可为光散射法传感器微站PM_2.5监测值校正提供有益参考.     

Constructing a Raman and surface-enhanced Raman scattering spectral reference library for fine-particle analysis

Fine particles associated with haze pollution threaten the health of over 400 million people in China. Owing to excellent non-destructive fingerprint recognition characteristics, Raman and surface-enhanced Raman scattering (SERS) are often used to analyze the composition of fine particles to determine their physical and chemical properties as well as reaction mechanisms. However, there is no comprehensive Raman spectral library of fine particles. Furthermore, various studies that used SERS for fine-particle composition analysis showed that the uniqueness of the SERS substrates and different excitation wavelengths can produce a different spectrum for the same fine-particle component. To overcome this limitation, we conducted SERS experiments with a portable Raman spectrometer using two common SERS substrates (silver (Ag) foil and gold nanoparticles (Au NPs)) and a 785 nm laser. Herein, we introduced three main particle component types (sulfate-nitrate-ammonium (SNA), organic material, and soot) with a total of 39 chemical substances. We scanned the solid Raman, liquid Raman, and SERS spectra of these substances and constructed a fine-particle reference library containing 105 spectra. Spectral results indicated that for soot and SNA, the differences in characteristic peaks mainly originated from the solid-liquid phase transition; Ag foil had little effect on this difference, while the Au NPs caused a significant red shift in the peak positions of polycyclic aromatic hydrocarbons. Moreover, with various characteristic peak positions in the three types of spectra, we could quickly and correctly distinguish substances. We hope that this spectral library will aid in the future identification of fine particles.     

Role of Hydrophilic and Hydrophobic Interactions in Structure Development of Zein Films

Zein has been studied for its potential as a biobased polymeric material. Due to the fact that films made exclusively from zein are brittle, composites of zein and oleic acid were prepared in our lab and formed into flexible films. Film properties were believed related to their structure. X-ray scattering measurements on zein films suggested the formation of layers along the plane of the film. Oleic acid seemed to play an important role in layer formation. However, X-ray measurements could not yield information on the nature of the interface between oleic acid and zein. Surface plasmon resonance (SPR) was used to further investigate interaction between zein and oleic acid. Dynamic adsorption of zein from alcoholic solutions onto hydrophilic and hydrophobic surfaces generated by self-assembled monolayers of 11-mercaptoundecanoic acid or 1-octanethiol was monitored by SPR. It was observed that zein had a greater affinity for hydrophilic than for hydrophobic surfaces under the prevalent experimental conditions. A mechanism for structure development of zein-oleate films was proposed based on these results and previous X-ray measurements. It is suggested that the structure development involves hydrophilic adsorption of fatty acids onto the zein surface followed by hydrophobic associations leading to a layered film structure organization.     

激光光散射在混凝研究中的应用评述

混凝研究的理论与实践近三十年来得到长足的发展，很大的原因在于现代检测技术与手段的大力运用，激光光散射为其中得力的方法之一。本文对其基本操作原理作了简要介绍，并对测定过程中存在的若干问题作了探讨。然后就其在混凝领域中诸层次的研究现状与发展趋势进行了若干概括。本文试图阐明其应用于混凝领域的研究所具有的巨大潜力及困难与局限所在，以期将来更大的进展     

Au/Fe3O4/GO复合SERS基底的制备及对水溶液中低浓度芘的富集-检测

以氧化石墨烯(GO)为载体,利用静电吸附将氨基修饰的Fe_3O_4磁性纳米颗粒负载到GO表面得到GO-Fe_3O_4复合材料,再通过静电作用将Au纳米颗粒与GO-Fe_3O_4复合材料组装,制备了Au/Fe_3O_4/GO复合材料,并考察其表面增强拉曼(SERS)活性.首先以罗丹明B(Rh B)为探针分子,考察Au纳米颗粒的粒径对SERS性能的影响,发现平均粒径为40 nm的Au纳米颗粒具有最好的SERS效果.SERS检测性能随着Au负载量的提高而逐渐变优,Au/GO中Au负载量为20%时最优.以多环芳烃分子芘为探针分子,探究Au/Fe_3O_4/GO复合材料中各组分对SERS性能的影响发现,Au纳米颗粒对拉曼信号的增强起主要作用,GO可以通过化学增强效应及对芘的吸附富集作用有效提高SERS检出限,Fe_3O_4的存在可以使基底快速分离,简化实验步骤,便于基底重复利用.该方法对水溶液中芘的检出限达到10-8mol·L-1,相对于普通拉曼的检出限有了明显的降低,有望被用于环境中痕量多环芳烃的富集-检测.     

SH波入射多个半圆形谷地浅埋圆孔的动力分析

应用辅助函数的思想，通过复变函数和多级坐标的方法给出了SH波入射条件下多个半圆形沉积谷地附近多个浅埋圆形孔洞动力分析问题的解答。求解过程中将整个求解区域划分成两部分来处理：区域Ⅰ为多个半圆形沉积谷地，区域Ⅱ为多个浅埋圆形孔洞附近带多个半圆形凹陷的半无限弹性空间。在区域Ⅰ和Ⅱ中分别构造位移解，并在二个区域的“公共边界”上实施位移、应力的连续条件，建立起求解该问题的无穷代数方程组。最后．给出了分析例题和数值结果．并对其进行了讨论。