Modern approaches for detection of volatile organic compounds in metabolic studies focusing on pathogenic bacteria:Current state of the art

Pathogenic microorganisms produce numerous metabolites,including volatile organic compounds(VOCs).Monitoring these metabolites in biological matrices(e.g.,urine,blood,or breath)can reveal the presence of specific microorganisms,enabling the early diagnosis of infections and the timely implementation of tar-geted therapy.However,complex matrices only contain trace levels of VOCs,and their constituent com-ponents can hinder determination of these compounds.Therefore,modern analytical techniques enabling the non-invasive identification and precise quantification of microbial VOCs are needed.In this paper,we discuss bacterial VOC analysis under in vitro conditions,in animal models and disease diagnosis in humans,including techniques for offline and online analysis in clinical settings.We also consider the advantages and limitations of novel microextraction techniques used to prepare biological samples for VOC analysis,in addition to reviewing current clinical studies on bacterial volatilomes that address inter-species in-teractions,the kinetics of VOC metabolism,and species-and drug-resistance specificity.

Remove volatile organic compounds(VOCs) with membrane separation techniques

Membrane separation, a new technology for removing VOCs including pervaporation, vapor permeation, membrane contactor, and membrane bioreactor was presented. Comparing with traditional techniques, these special techniques are an efficient and energy saving technology. Vapor permeation can be applied to recovery of organic solvents from exhaust streams. Membrane contactor could be used for removing or recovering VOCs from air or wastewater. Pervaporation and vapor permeation are viable methods for removing VOCs from wastewater to yield a VOC concentrate which could either be destroyed by conventional means, or be recycled for reuse.

Study on compound ultra-precision alignment technique

A nano-displacement measurement system with duo-gratings is analyzed by using optics theory,a math- ematic model for the system is established,and the characteristic of laser Moirésignals is studied through CAD simu- lation.To improve signal sensitivity and positioning accuracy,two methods of precision positioning are brought for- ward:differential Moirépositioning method and modified Moirépositioning method.A compound control system for precision positioning is set up by combining these 2 Moiréalignment methods,in which the modified Moiréalignment technique is used for coarse alignment and the differential Moiréalignment technique is used for fine alignment,and the system obtains positioning accuracy of±10 nm in±500μm positioning range with shot response time.

THE DAMAGE MEASUREMENT OF ION- IMPLANTED COMPOUND SEMICONDUCTOR GaAs BY PIXE-CHANNELING TECHNIQUE

A combined PIXE-RBS channeling measurement system to examine Ⅲ-Ⅴ compound semiconductors has been established. Preliminary results on studying Si+ and Te+ implanted GaAs have been presented and discussed.

Experimental Study on the Feasibility of Methane Drainage in Coal Seams with Compound Technique of Perforating and Fracturing

Compound technique of perforating and fracturing can effectively control the perforating direction and the fracturing expansion. The feasibility of this technique used in fracturing coal seams is analyzed. In this paper, the experiments of perforating and fracturing are carried out on samples of coal and the experimental effects are satisfactory. Compound technique of perforating and fracturing is promising in coal seams.

Characterization of CdZnTe crystal grown by bottom-seeded Bridgman and Bridgman accelerated crucible rotation techniques

The growth of CdZnTe crystals with diameter up to 60 mm using bottom-seeded Bridgman method as well as Bridgman accelerated crucible rotation technique (ACRT-B) was investigated. Both ingots exhibit high yields, where single crystal with the volume exceeding 200 cm3 is produced. The crystal properties of two ingots were compared in the aspects of yields, crystalline quality and composition uniformity. For CdZnTe ingot grown by bottom-seeded Bridgman method, the full width at half-maximum (FWHM) of X-ray rocking curve was determined to be 36″, indicating a better crystalline quality than ingot grown by ACRT-B method, which gave FWHM of 56″. The composition distribution of Zn and In in CdZnTe was determined by using electron probe microanalysis (EPMA) and inductively coupled plasma mass spectrometry (ICP-MS), respectively. The effective segregation coefficients of Zn kZn and In kIn in the two ingots were evaluated by fitting the experimental data with the Pfann equation.

Nonlinear optical properties of [（CH3）4N]Au（dmit）2 using Z-scan technique

The third-order optical nonlinearities of [（CH3）4N]Au（dmit）2 （dmit = 4,5-dithiolate-1,3-dithiole-2-thione） at 532 nm and 1064 nm are investigated using the Z-scan technique with pulses of picoseconds duration. The Z-scan spectra reveal a strong nonlinear absorption （reverse saturable absorption） and a negative nonlinear refraction at 532 nm. No nonlinear absorption is observed at 1064 nm. The molecular second-order hyperpolarizability γ for the [（CH3）4N]Au（dmit）2 molecule at 532nm is estimated to be as high as （2.1 ±0.1） × 10^-31 esu, which is nearly three times larger than that at 1064 nm. The mechanism responsible for the difference between the results is analysed. Nonlinear transmission measurements suggest that this material has potential applications in optical limiting.

大豆玉米带状复合种植技术探讨

大豆玉米带状复合种植技术可以充分发挥大豆固氮作用和玉米边际效应,实现良种良法配套、农技农艺融合、种地养地有机结合,有效解决传统作物套种生产效率低下、争光、争肥和争水等问题,有效提升农业生产效益。以灵台县农业生产实际情况为例,对大豆玉米带状复合种植技术进行研究,以期为广大种植户提供技术参考。

不同预处理和干燥方式下养心菜粉色泽、功能成分和抗氧化性水平的比较

为了研究养心菜的加工适用性,拓展其利用途径,采用未预处理(Untreated,UT)、沸水漂烫(Boiling Water Blanching,BWB)、沸水+护色漂烫(COLOR Protection+Water Blanching,CPB)、蒸汽漂烫(Steam Blanching,SB)与冻融(Freeze-Thawing,FT)五种预处理方式处理后,分别进行热风干燥(Hot Air Drying,HA)、热泵干燥(Heat Pump Drying,HP),得到UT HP、UT HA、BWB HP、BWB HA、CPB HP、CPB HA、SB HP、SB HA、FT HP及FT HA 10种养心菜粉,比较不同预处理方式和干燥方式下养心菜色泽、功能成分及抗氧化能力水平的变化。结果表明:UT HP没食子酸和山萘酚含量最高,但色泽差、叶绿素含量较低,干燥时间长;CPB HP的干燥时间短,Vc含量最高,具有较高的抗氧化水平,但没食子酸含量较低;SB HP总酚、总黄酮、槲皮素含量最高,其他品质指标介于中间;FT HP养心菜具有最好的色泽、最高的叶绿素、游离氨基酸含量,但总酚、总黄酮、槲皮素、山萘酚以及抗氧化水平低。从主成分分析来看,BWB HP、CPB HP、SB HP和BWB HA、CPB HA、SB HA的养心菜品质分别具有一定的相似性,UT HP、FT HP、UT HA、UT HA和其有明显差异。该文综合比较了养心菜不同预处理及干燥方法的优劣,在养心菜下游的功能性食品的开发过程中,可以根据需求选择合适的干燥方法。

油茶籽油生物活性成分、风味物质及脂质组成研究进展

油茶是世界四大木本油料作物之一,油茶籽油是富含不饱和脂肪酸的传统食用油,备受人们青睐。生物活性成分含量、风味物质和脂质组成是评价植物油品质和消费者选择食用油的重要依据。油茶籽油生物活性成分主要有角鲨烯、生育酚、植物甾醇、多酚和类胡萝卜素,其具有抗炎、抗氧化和抗肿瘤等作用。本文对油茶籽油生物活性成分、风味物质以及脂质组成的最新研究进展进行了全面概述,重点介绍了油茶籽油中生物活性成分的种类和功效、挥发性风味物质和脂质组成检测方法、产生挥发性化合物的物质基础及影响油茶籽油风味形成的因素,并对油茶籽油产业的健康发展进行了展望。

水产品挥发性风味化合物生成机理及其分析技术研究进展

水产品是海洋和淡水渔业生产的水产动植物产品及其加工产品的总称,营养丰富,蛋白质含量是禽畜产品的2~4倍,且易于人体吸收,含有维生素和矿物质(如维生素D、硒、磷和钙等)。此外,水产品提供的n-3多不饱和脂肪酸,包括二十碳五烯酸和二十二碳六烯酸,对大脑发育起着重要作用^([1])。随着我国居民收入、生活水平提高,国民膳食结构逐渐优化,水产品的食物健康功能越来越受到重视,水产品在居民膳食中的比重越来越高,消费需求量也越来越大。根据《中华人民共和国2021年国民经济和社会发展统计公报》报道,2021年我国全年水产品产量6693万t,比上年增长2.2%。2021年渔业产值14 507亿元,比2012年增加6103亿元,2013—2021年年均增长3.4%^([2])。

用于太阳光泵浦光纤激光聚光系统的改进型复合抛物面聚光器的设计

为研制适用于太阳光泵浦光纤激光器的聚光系统,在分析了传统复合抛物面聚光器(CPC)用于耦合光纤的可行性及其缺陷的基础上,提出了一种改进型CPC用于光纤耦合。完成了由主级抛物面反射镜和次级改进型CPC组成的太阳光泵浦多级聚光方案,并与普通CPC和透镜组构成次级聚光器的方案以及无次级聚光器的方案进行了对比。光线追迹仿真模拟结果表明:改进型CPC能够克服普通CPC出射光线发散的缺陷,从而提高与光纤的耦合效率,当主镜接收角度在±0.55°范围内,其耦合效率维持在93.53%-96.43%,该结果优于其他方案。

基于Web of Science的挥发性有机化合物无创诊断肿瘤文献计量与可视化分析

目的对近20年使用挥发性有机化合物(VOCs)进行肿瘤无创诊断的研究展开文献计量及可视化分析,总结其研究现状、不足及发展趋势,为未来临床实施应用提供参考。方法以“neoplasia”和“volatile organic compound”为共同主题,采用主题词和自由词结合的方式,检索2002年1月1日至2022年10月26日发表在Web of Science核心合集数据库的VOCs无创诊断肿瘤相关研究,通过Citespace和VOSviewer软件生成知识图谱,对年度出版物、国家、作者机构、出版物、参考文献及关键词进行可视化分析。结果经检索共纳入641项研究,年度发文量整体呈上升趋势。“肺癌”“呼出气”一直是该领域核心组成部分;传感器检测技术在更多癌症中应用和发展,以及探索潜在特异性生物标志物成为新的研究趋势。结论利用VOCs进行肿瘤无创诊断将继续成为一个活跃的研究领域,但追求创新的同时,还需考虑实际需求,如果没有统一的操作标准,不是特定癌种可靠且可重复的生物标志物群,VOCs的临床应用依然会受到极大限制。

Crystal growth of Gd_2PdSi_3 intermetallic compound

Gd2PdSi3 single crystals were grown by a vertical floating zone method with radiation heating at a zone traveling rate of 3 mm/h. The compound exhibited congruent melting behavior at a liquidus temperature of about 1700 ＆#176;C. The slightly Pd-depleted composition of the crystal, with respect to the nominal Gd2PdSi3 stoichiometry, led to gradual accumulation of Pd in the traveling zone and to a decreasing operating temperature during the growth process. Thin platelet-like precipitates of a GdSi phase were detected in the stoichiometric feed rod growth crystal matrix which can be reduced by annealing treatment. Feed rod composition shift crystal growth was proved to be a better way of getting high quality of Gd2PdSi3 single crystal.

基于改进的辛周期模态分解的滚动轴承复合故障诊断方法

辛周期模态分解(symplectic period mode decomposition, SPMD)方法可以准确地提取周期脉冲分量,是一种有效的滚动轴承单一故障诊断方法。但在滚动轴承出现复合故障时,尤其是强背景噪声下,周期脉冲信号往往较微弱,使得SPMD难以提取出不同周期的脉冲分量,进而限制了其在复合故障诊断中的应用。对此,提出了改进的辛周期模态分解(improved symplectic period mode decomposition, ISPMD)方法。该方法首先采用求差增强技术和最小噪声幅值反卷积相结合的方法对信号进行降噪,增强周期脉冲,以准确估计故障周期;然后构造对应的周期截断矩阵,并通过辛几何相似变换和周期冲击强度获得辛几何周期分量;最后对残差信号采用迭代分解,进而得到不同周期的辛几何周期分量。试验结果表明,ISPMD能准确提取出周期脉冲分量,是一种有效的滚动轴承复合故障诊断方法。

铂基纳米制剂平台在医学多模态成像中的应用

铂基纳米制剂平台由于铂的高原子序数存在,能够增强对X线的吸收,应用于CT成像。同时铂基纳米材料具有良好的近红外光吸收特性和光热转换效应,使其具有光热成像和光声成像能力。另外,通过减少横向和纵向弛豫时间,铂基纳米制剂平台可以介导MRI。本文对基于铂基纳米制剂平台的多模态成像系统引导癌症治疗诊疗平台开发和医学应用研究进行综述,分析利用铂基纳米制剂平台的多模态成像技术在癌症诊断和治疗中的应用前景,总结基于铂基纳米制剂平台在改善医学图像的对比度和提高癌症治疗效果方面的研究进展。

日光温室水果黄瓜岩棉椰糠复合基质高效栽培技术

为了解决当前土壤种植条件下土壤病原菌富集、盐分积累、土壤酸化等问题,本文总结了日光温室水果黄瓜岩棉椰糠复合基质高效栽培技术,包括日光温室准备、基质栽培系统构建、品种选择、育苗、栽培管理、吊蔓整枝、采收、采后处理等方面内容,以期实现水果黄瓜的周年无障碍生产,达到效益提升的目的。

炼化企业VOCs及异味治理技术要点与应用研究

通常,炼化企业在生产过程中会出现大量的挥发性有机物(Volatile Organic Compounds,VOCs)及异味,不仅对周围生态环境造成严重的破坏,同时对企业员工身体健康造成较大的威胁。因此,需要通过合理的治理技术,控制好炼化企业VOCs与异味的出现。基于此,结合具体工程案例,以电子技术为基础,对炼化企业VOCs与异味治理的具体技术要点进行研究分析,同时对不同电子技术的应用效果进行概括,以期为相关人员提供参考。

复方黄柏液坐浴辅助内口封闭联合负压封闭引流技术治疗高位肛周脓肿的效果

目的:分析复方黄柏液坐浴辅助内口封闭联合负压封闭引流技术治疗高位肛周脓肿的效果。方法:选取2020年4月—2022年11月深圳出入境边防检查总站医院收治的100例高位肛周脓肿患者作为研究对象,随机分为两组,各50例。对照组采取内口封闭联合负压封闭引流技术治疗,观察组在对照组基础上实施复方黄柏液坐浴治疗。比较两组治疗效果。结果:观察组治疗总有效率高于对照组,差异有统计学意义(P=0.014)。观察组创面疼痛以及创面水肿评分低于对照组,愈合时间短于对照组,差异有统计学意义(P<0.001)。治疗前,两组C反应蛋白(CRP)、肿瘤坏死因子-α(TNF-α)、白细胞介素-6(IL-6)水平比较,差异无统计学意义(P>0.05);治疗后,两组CRP、TNF-α、IL-6水平低于治疗前,且观察组低于对照组,差异有统计学意义(P<0.05)。治疗前,两组5-羟色胺(5-HT)、去甲肾上腺素(NE)、P物质(SP)水平比较,差异无统计学意义(P>0.05);治疗后,两组5-HT、NE、SP水平低于治疗前,且观察组低于对照组,差异有统计学意义(P<0.05)。结论:复方黄柏液坐浴辅助内口封闭联合负压封闭引流技术治疗高位肛周脓肿的效果显著,可促进创面恢复,减轻炎性反应,缓解疼痛。

水泥窑协同处置技术在污染场地土壤修复中的工程实践

四川某机械设备厂的污染场地问题是土壤中苯系物及石油烃含量超标,对人体健康构成威胁。为有效解决这一问题,经过慎重考量,项目施工方决定采用水泥窑协同处置技术进行污染土壤修复工作。在既定工期内,施工方经过精心组织施工,成功完成了修复工作。经过专业评估和验收,该工程治理效果显著,土壤质量得到明显改善,污染物浓度大幅降低,达到了预期目标。