吉林省辽源市中小学生头发中六种微量元素含量水平的研究

测定了辽源市1147例中小学生头发中Zn、Fe、Cu、Ca、Mn和Pb的含量,讨论了其百分位含量和正常值范围,研究了各元素含量在性别、年龄上的差异性和相关性,观察、分析了用计算机模式识别技术所得到的不同年龄、性别的样本点的二维聚类、分布图,为该地区微量元素科学的研究提供了有价值的信息和数据。     

微量元素既可载舟又可覆舟

“先天不足”和“后天失调”的全球性“元素病”,引起了各国政府的关注。中国政府出台了一系列法律文件,成立了国家级的相应机构进行调研和治理。与此同时,加大了元素科学和生命科学的教育和宣传力度,取得可喜的成绩,控制了“碘缺乏病”和“硒缺乏病”,儿童锌缺乏率和儿童铅超标率下降。为了减少各种慢性病的发病率,卫生部、国家计委、教育部、科技部、民政部、财政部、农业部、贸易部、国务院扶贫办公室、     

微量元素既可载舟又可覆舟

“先天不足”和“后天失调”的全球性“元素病”,引起了各国政府的关注。中国政府出台了一系列法律文件,成立了国家级的相应机构进行调研和治理。与此同时,加大了元素科学和生命科学的教育和宣传力度,取得可喜的成绩,控制了“碘缺乏病”和“硒缺乏病”,儿童锌缺乏率和儿童铅超标率下降。为了减少各种慢性病的发病率,卫生部、国家计委、教育部、科技部、民政部、财政部、农业部、贸易部、国务院扶贫办公室、轻工总会、全国妇联等11个部委联合制订了《中国营养改善行动计划》,     

气相色谱仪验证要点

介绍分析仪器验证的基本概念和主要内容。总结了气相色谱仪验证中设计确认、安装确认、运行确认和性能确认的验证过程和要点,详细介绍了验证内容、具体项目、参考指标、参与人员、时间频次和要点等内容,指出了气相色谱仪验证需要注意的问题,提出了气相色谱仪验证工作的改进建议,为气相色谱仪器验证提供技术参考。     

介孔氧化铝的制备及应用

本文介绍了介孔氧化铝(MA)的各种制备方法,概括了MA制备的分析表征方法,如TEM、SAED、XRD、LAXRD、气体吸附-脱附、DT-TGA等。通过平均孔径、比表面积、MA形貌等因素,讨论和总结了制备方法、铝源、模板剂、反应物配比、pH值和后处理方法等对MA制备和热稳定性的影响,综述了近年来MA的研究和应用进展,并对今后的研究方向进行了展望。     

钙钛矿型高温质子导体研究进展

介绍了钙钛矿型和复合钙钛矿型化合物的结构、常用的制备方法和传导性质,详细分析了其传导机理,评述了其研究进展和在气体传感器、固体燃料电池、有机物加氢和脱氢以及常压电化学合成氨等方面的应用,展望了应用前景和发展趋向.     

大气光化学反应研究（Ⅱ）—二氧化硫与异戊烷的光化学反应

研究了SO_2与异戊烷在无氧和有氧体系中的光化学反应,用GC和GC-MS法确证了部分气、液相产物,包括醇、醛、酮、酯和烃类及含硫有机物,探讨了影响光化学反应的因素和反应机理.     

Ce、Zr、Pd物种的掺杂对NiMgAl类水滑石及衍生复合氧化物催化性能影响

用水热法分别合成了NiMgAl、NiMgCeAl、NiMgZrAl和NiMgPdAl类水滑石,重点考察了Ce、Zr和Pd物种的掺杂对NiMgAl类水滑石结构及衍生复合氧化物的催化性能影响。用XRD、TPR、TPD、TPO和BET等对不同类水滑石及衍生复合氧化物的晶相结构、表面性能等进行了表征,结果表明,Ce物种的掺杂提高了衍生复合氧化物的比表面积,催化活性和抗积碳性能,掺杂Pd提高了H2吸附性能、催化活性和抗积碳性能,而掺杂Zr物种其衍生复合氧化物的比表面积和催化活性有所降低。     

我国金属中气体分析的回顾

近几年来,我国金属中气体分析得到了很大的发展。使用了一些新的技术和方法;研制了各种型号的新仪器,制定了部分标准方法和制备了部分标准试样。同时召开了数次全国性和地区性的报告会和鉴定会,肯定了成果,交流了经验。本文仅就我国金属中气体分析的进展作一简要的回顾。一、热源和测试方法我国金属中气体(指氧、氮、氢)分析,开展较早的单位是科学院金属研究所、有色总公司北京有色金属研究总院和冶金部钢铁研究总院。他们在50年代就建立了真空熔融微压法的实验装置,开展了黑     

微流控芯片电泳的研究进展

该文综述了微流控芯片电泳的制备、结构和应用,比较了不同材料微流控芯片电泳的制备机理、表面改性和性能特点,归纳和总结了不同结构微流控芯片电泳的进样、分离和检测系统以及不同类型微流控芯片电泳在荧光物质、金属离子、糖、药物、核酸、DNA、氨基酸、多肽和蛋白质分析中的应用,并对微流控芯片电泳的未来发展方向做了展望.     

Hard X-ray multilayer mirror round-robin on the wavefront preservation capabilities of W/B4C coatings

A round-robin between the multilayer deposition laboratories of the Advanced Photon Source, the European Synchrotron Radiation Facility and the National Synchrotron Light Source II has been initiated in order to study standard W/B₄C multilayer mirrors produced by the different facilities. The use of such multilayer mirrors for hard X-ray monochromatisation represents an important alternative to crystal-based devices when greater photon flux density is desirable for, e.g., X-ray imaging applications and other photon-intensive techniques. Currently, knowledge about the potential degradation of the wavefront in terms of beam profile distortion and coherence properties due to reflection on a multilayer mirror is limited. In order to address this issue, the beam profile and coherence properties of a monochromatic synchrotron beam reflected by the individual mirrors were studied at the Advanced Photon Source insertion device beamline 32-ID. The results indicate that by using the same coating material, commercially available high quality substrates and a similar coating technique, mirrors with comparable performance can be produced with quite different multilayer deposition facilities. Furthermore, no wave-optical formalism is available at this time which relates the influence of a multilayer reflection on the wavefront to the structural quality of the mirror. Hence, the experimental studies presented are highly targeted in order to identify parameters which have a potential influence on the wavefront preservation properties of a multilayer.     

LB技术组装聚合物／有机染料多层膜的光致发光和电致发光

半导体超晶格材料由于其特殊的光电性质引起人们的关注,So和Tokito等人用分子束沉积的方式制备了有机及有机无机复合的超晶格材料器件,但分子沉积中有机小分子染料的结晶影响薄膜的质量及器件的寿命。最近,我们用两亲性聚合物分子成功地将有机染料分子组装在聚合物LB膜中,有效地限制有机小分子染料结晶,实验证明此多层LB膜具有超晶格结构和较好的稳定性及发光特性。为制备多量子阱结构器件提供了一种新方法。 两亲性聚合物(ES)是由环氧氯丙烷、乙二胺和硬脂酸共聚而成。将染料分子四苯基丁二烯(TPB)与ES相混合的氯仿溶液(TPB与ES质量比为2:10)分散在去离子水亚相表面,在20mN/m的膜压下将其转移到单晶硅片上。用小角X射线衍射实验观察其多层结构,在小角衍射区存在一个Bragg衍射峰(图1),根据Bragg衍射方程得到其层状周期结构为5.8nm。考虑到ES的分子尺寸,我们认为每一周期结构是由两层聚合物的LB膜组成。由于TPB分子是疏水的,通过分子间的相互作用,TPB分子可能镶嵌或吸附在ES的疏水脂肪链中,与无机半导体超晶格结构对照,聚合物ES的亲水网络由于是绝缘材料,带隙很宽相当于能垒,而镶嵌有TPB的疏水层则相当于势阱,这就很可能形成聚合物/有机染料的超晶格结构。考察其发光特性(图2)时,发现聚合物/有机染     

Preliminary synchrotron radiation characterization of first multilayer mirrors for the soft X-ray water window

The development of high-reflectivity devices for soft X-rays at quasi-normal incidence is a challenging research for the development of synchrotron radiation optics, particularly for soft X-ray microscopy and X-ray microprobe spectroscopy. Here we present data concerning the deposition of the first Ni/Ti and Ni/TiO₂ multilayers grown at the INFN Legnaro Laboratories (LNL). These multilayers have a lattice spacing in the order of 14 Å and more than 100 of bilayers. Experimental tests on these multilayers have been performed by a vacuum compatible θ–2θ reflectometer, set up at the INFN Frascati Laboratories (LNF), where their characterization has been accomplished by means of synchrotron radiation.The first multilayer mirrors tailored in order to work at quasi-normal geometry have been measured in the lower X-ray energy domain using both white-beam and monochromatic radiation at about 1 keV.     

Microscopy and microspectroscopy with soft X-rays

The availability of synchrotron radiation from undulators is the basis of a new probe of tunable X-rays. The realization of such a probe requires to produce a demagnified image of the monochromatized radiation from the source on the sample. For this purpose Fresnel zone plates, multilayer covered mirrors, and mirrors at grazing incidence are available. The probe sizes presently are between 30 nm and 1 m.In the scanning microscope at HASYLAB/DESY in Hamburg a grazing incidence ellipsoid mirror is used to focus radiation in the energy range 15 eV to 1200 eV to a spot of 1 m. In the VUV-region below 30 eV a normal incidence Schwarzschild objective allows a spatial resolution of 100 nm. The signals which are available for microscopy and microspectroscopy are transmission, photoelectrons, luminescence in the visible, UV and soft X-ray regions, scattered light and desorbed ions. Spectrometers for photoelectrons and visible/UV-luminescence are installed for secondary spectroscopy. Several of the signals are not only element specific but also specific to the chemical environment and binding character. Most of the techniques are very surface sensitive. Different projects are reviewed while we concentrated mainly on examples from our own station.     

Electric-field-induced fabrication of covalently linked second-order nonlinear optical multilayer films on nonconductive substrates

A highly stable second-order nonlinear optical multilayer film was constructed on insulating substrates using the electric-field-induced layer-by-layer assembly technique. The substrates used in this method could be arbitrary. In another, the substrates could be modified with polyanion solution by spin coating as cladding layer. Then, the nonlinear optical multilayer films were assembled on the cladding layer directly by the electric-field-induced layer-by-layer assembly technique. The resulting cross-linked multilayer films fabricated by this method displayed high optical transparency, good thermal stability, and excellent nonlinear optical properties which can be made into waveguide devices directly.     

A multireflection cell for enhanced absorbance detection in microchip-based capillary electrophoresis devices

The design, fabrication and testing of a photolithographically fabricated, glass-based multireflection absorbance cell for microfluidic devices, in particular microchip-based capillary electrophoresis (CE) systems is described. A multireflection cell was fabricated lithographically using a three-mask process to pattern aluminum mirrors above and below a flow channel in a chip, with 30 microm diameter optical entrance or exit apertures (one in each mirror) positioned 200 microm apart. Source and detector were positioned on opposite sides, and the metal mirrors were made 1 cm square, to reduce stray light effects. Calibration curves using bromothymol blue (BTB) with a 633 nm source (He:Ne laser) were linear to at least 0.5 absorbance units, with typical r2 values of 0.9997, relative standard deviations in the slopes of +/- 1.3%, and intercepts of zero within experimental error. Effective optical pathlengths of 50-272 microm were achieved, compared to single-pass pathlengths of 10-30 microm, corresponding to sensitivity enhancements (i.e., optical path length increase) of 5 to 10-fold over single-pass devices. Baseline absorbance noise varied within a factor of two in almost all devices, depending only weakly on path length. This device can give much higher absorbance sensitivity, and should be much easier to manufacture than planar, glass-based devices previously reported.     

Spray-layer-by-layer assembly can more rapidly produce optical-quality multistack heterostructures

Automated spray-layer-by-layer (LbL) assembly was used to create highly reflective structurally colored thin films with high reflectance at near-UV light wavelengths. Reflectance peaks were tuned by fabricating alternating stacks of high (TiO(2) nanoparticles) and low (SiO(2) nanoparticles) refractive index materials using a non-quarter-wave design. Spray-assembled multilayer heterostructures fabricated with up to 840 individual polymer or nanoparticle deposition steps presented similar roughness and refractive index values compared to Bragg stacks obtained via immersion LbL assembly. Such complex multilayer heterostructures, however, could be fabricated in significantly shorter times; the time required to deposit a complete bilayer was only about 90 s, compared to 36 min for the immersion assembly of the same system. Optimization of the experimental parameters was performed to achieve uniform coatings and relatively smooth interfaces and surfaces. We observed that the spraying times of the nanoparticle and polymer solutions are the main parameters that determine the thickness, optical properties, and uniformity of the assembled films. Ellipsometry, atomic force microscopy (AFM), UV-vis spectroscopy, and transmission electron microscopy (TEM) were used to characterize the samples. The nanoparticle thin films were iridescent and presented relatively narrow peaks of high reflectance (～90%) at visible and near-UV wavelengths of light.     

Comparative X-ray standing wave analysis of metal-phosphonate multilayer films of dodecane and porphyrin molecular square

The nanoscale structures of multilayer metal-phosphonate thin films prepared via a layer-by-layer assembly process using Zr(4+) and 1,12-dodecanediylbis(phosphonic acid) (DDBPA) or porphyrin square bis(phosphonic acid) (PSBPA) were studied using specular X-ray reflectivity (XRR), X-ray fluorescence, and long-period X-ray standing wave (XSW) analysis. The films were prepared in 1, 2, 3, 4, 6, and 8 layer series on both Si(001) substrates for XRR and on 18.6 nm period Si/Mo layered-synthetic microstructure X-ray mirrors for XSW. After functionalizing the SiO(2) substrate surfaces with a monolayer film terminated with phosphonate groups, the organic multilayer films were assembled by alternating immersions in (a) aqueous solutions containing Zr(4+)or Hf(4+) (final metal layer only) cations and then (b) organic solvent solutions of PO(3)-R-PO(3)(4-), where R was DDBPA or PSBPA spacer molecule. The Hf(4+) cation served as the marker for the top surface of the films, whereas the Zr(4+) cation was present in all other layers. The PSBPA also contained Zn and Re atoms at its midline which served as heavy-atom markers for each layer. The long-period XSW generated by the 0th- (total external reflection) through 4th-order Bragg diffraction conditions made it possible to examine the Fourier transforms of the fluorescent atom distributions over a much larger q(z) range in reciprocal space which permitted simultaneous analysis of Hf, Zn/Re, and Zr atomic distributions.     

Layer-by-layer engineered Co-Al hydroxide nanosheets/graphene multilayer films as flexible electrode for supercapacitor

Multilayer films of Co-Al layered double hydroxide nanosheets (Co-Al LDH-NS) and graphene oxide (GO) were fabricated through layer-by-layer (LBL) assembly. By using a three-electrode system, the electrochemical performances of the films were investigated to evaluate their potential as electrode materials to be used in flexible supercapacitor devices. The Co-Al LDH-NS/GO multilayer films exhibited a high specific capacitance of 880 F/g and area capacitance of 70 F/m(2) under the scan rate of 5 mV/s. And the film exhibited good cycle stability over 2000 cycles. After treating the films at 200 °C in H(2) atmosphere, the specific capacitance and area capacitance were largely increased up to 1204 F/g and 90 F/m(2) due to partial reduction of GO. A flexible electrode by depositing Co-Al LDH-NS/GO multilayer film onto PET substrate was prepared to show the potential of Co-Al LDH-NS/GO films for flexible energy storage.     

Use of a ruthenium-containing conjugated polymer as a photosensitizer in photovoltaic devices fabricated by a layer-by-layer deposition process

Multilayer polymer films composed of a ruthenium terpyridine complex containing poly(p-phenylenevinylene) (Ru-PPV) and sulfonated polyaniline (SPAN) were prepared by a layer-by-layer electrostatic self-assembly deposition. The deposition process was carried out from SPAN solution in water and Ru-PPV in dimethylformamide (DMF). Optical-quality multilayer thin films were obtained. The film growth process was monitored by quartz crystal microbalance, and the surface morphology of the films was studied by atomic force microscopy. It was found that the properties of the multilayer films were dependent on deposition conditions such as the pH of the SPAN solution, the presence of salt in the polymer solutions, and the post-film-forming thermal annealing process. Cross-section transmission electron microscopic images suggested that there was no stratified structure formed in the multilayer films. Photovoltaic cells were fabricated by sandwiching the multilayer films between indium-tin-oxide and aluminum electrodes. The device performances were examined by illumination with AM 1.5 simulated solar light. The power conversion efficiencies of these devices were on the order of 10(-3)%. The maximum incident photon-to-electron conversion efficiency (IPCE) of the devices was found to be approximately 2% at 510 nm, which is consistent with the absorption maximum of the ruthenium complex. This indicates that the photosensitization process is due to the electronic excitation of the ruthenium complex.