基于重水拉曼技术评价口腔抑菌剂对粪肠球菌抑菌效能的研究

目的:开发有效且对患者副作用小的口腔抑菌剂配方,系统评价过氧化氢(hydrogen peroxide,H_(2)O_(2))、次氯酸钠(Sodium hypochlorite,NaClO)对粪肠球菌(Enterococcus faecalis ATCC29212)的抑菌效能。方法:分别采用肉汤稀释法和重水拉曼技术(D_(2)O-labeled single-cell Raman micro-spectroscopy),通过最小抑菌浓度(minimum inhibitory concentration,MIC)和最低抑制代谢浓度(minimum inhibitory concentration based on metabolic activity,MIC-MA)定量评价了抑菌剂对粪肠球菌的生长和代谢抑制作用。结果:对于过氧化氢和次氯酸钠,MIC分别为110 mg/L和0.45 g/L,尽管生长完全停止,但细菌细胞的代谢活性在8 h平均降低了71%、70%,显示出一种“非生长但代谢活跃”(NGMA)的状态,这种状态可能导致潜在的难治性反复感染。而MIC-MA分别为220 mg/L和0.9 g/L时,所有细胞的代谢活动在暴露8 h后完全停止。此外,NaClO+H_(2)O_(2)的组合使用优于单独使用次氯酸钠、过氧化氢。结论:MIC-MA有利于严格评估抗细菌疗效,NaClO+H_(2)O_(2)可作为细菌病原体更有效的抑菌剂方案。

显微红外光谱仪与显微拉曼光谱仪对纺用无色单根纤维的检测

目的研究常见纺用单根无色纤维的有效鉴别方法。方法使用显微红外光谱仪、显微激光拉曼光谱仪研究7大类纺用单根无色纤维的分子光谱。结果显微红外光谱仪、显微激光拉曼光谱仪能有效区分包括棉、粘胶、羊毛、丝、聚酰胺、聚丙烯腈和聚酯在内的7种纤维,是检测单根纤维的有效手段。785nm激发光源是显微激光拉曼光谱仪研究这7类纤维的最佳波长。但由于纺用纤维生产过程的标准化,仅依据红外或者拉曼的峰位置区分同种类、不同产地纤维的效果一般。结论显微红外光谱仪、显微激光拉曼光谱仪是鉴别常见纺用单根无色纤维的有效方法。

亚氯酸盐预处理杉木细胞壁木质素溶解机理研究

为了探究亚氯酸盐预处理过程中植物细胞壁木质素的区域化学溶解机理,采用紫外-可见光光谱与共聚焦拉曼显微光谱,对杉木管胞细胞壁在不同预处理时间亚细胞区域木质素分布规律及其含量变化进行了研究。结果表明:亚氯酸盐预处理杉木细胞壁木质素的溶解总体上分为4个阶段,木质素少量溶解(Ⅰ),反应溶液缓慢渗透到样品内部(Ⅱ),快速脱除内部大量木质素(Ⅲ),反应平衡阶段(Ⅳ)。尽管杉木细胞壁各层,细胞角隅(CC)、胞间层(CML)及次生壁(SW)都具有木质素的存在,但木质素在细胞壁不同形态区域中的分布具有明显的不均一性,因此在亚氯酸盐预处理过程中细胞壁不同形态学区域木质素的脱除速率不同,大量脱除木质素阶段(8~10 min)时呈现CC>CML>SW的规律。

哀牢山—红河剪切带中流体记录及地质意义

剪切带作为大陆岩石圈中的局部高应变带,是岩石变质-变形作用和流体活动的重要场所。沿着哀牢山—红河走滑剪切带内发育的点苍山深变质杂岩,保存了新生代以来极其丰富的构造-热演化信息。在点苍山杂岩体内出露有一系列具有不同构造特征的石英脉,我们选取了遭受剪切变形的石英脉作为主要研究对象,在野外构造观测和室内显微构造特征分析的基础上,利用傅立叶变换红外光谱(FTIR)、激光拉曼显微光谱(LRM)以及流体包裹体技术(FI)对其开展了进一步的精细研究。研究结果表明:(1)变形石英脉在显微镜下具有不同类型的塑性变形特征,其中以强烈细粒化和动态重结晶为主要特征的石英颗粒中包裹体类型主要为CO_2-H_2O包裹体和纯CO_2流体包裹体,包裹体多沿颗粒边界分布;在以条带状和细粒化为主要特征且具有典型核-幔构造的石英颗粒中,重结晶颗粒基本不含流体包裹体,石英条带中含有大量水溶液包裹体;在定向拉长的粗颗粒石英中其变形行为主要表现为波状消光和局部应变导致的塑性流动构造,在该类型石英颗粒中只含有水溶液包裹体且无明显分布特征。(2)根据各类流体包裹体测温数据估算出包裹体捕获温压为500～550℃、260～290MPa,深度约为10km,其流体来源主要为变质流体,剥露过程中的快速降压使得流体发生相分离及变形作用并导致的水丢失,这是CO_2-H_2O包裹体与水溶液包裹体出现的主要原因。(3)石英脉中的石英颗粒除含有一定量的包裹体水之外还含有少量的结构水,水在颗粒内部的分布为非均匀状态,通常边部水含量高于核部,同时水的分布特征和含量可随包裹体的变化而改变。(4)重结晶石英颗粒中的包裹体常在颗粒边界富集,认为其边界局部流体压力和流体的渗透或释放能弱化晶体平面,促进晶格位错滑移和溶解蠕变。

Corrosion behaviors and mechanism of electroless Ni-Cu-P/n-TiN composite coating

In the present investigation, electroless Ni-Cu-P/n-TiN composite coating was prepared using alkaline citrate-based bath. X-ray diffraction （XRD）, scanning electron microscopy（SEM）, energy-dispersive spectroscopy（EDS）, electrochemical measurements, weight loss tests and Raman spectrometer were used to character the properties of the coating. As the Cu content increased from 7.3 wt% to 24.8 wt%, the corrosion current density of the Ni-Cu-P/n-TiN coating decreased from 10.80 to 4.34 ~tA. And the inclusion of Cu in NiP alloy resulted in refinement and less porosity in microstructure. The addition of TiN resulted in a slight decline in anti-corrosion property of the coating. As the mass loss test showed, Ni-24.8%Cu-P exhibited perfect corrosion resistance. Studies by Raman spectroscopy on coatings proved that Cu（II）3（PO4）（OH）3, Cu（OH）2 and CuO were examined while no compound of nickel was found, and Cu exhibited preferred corrosion in saline solution, providing cathodic protection to Ni alloy.

Study on fluid inclusions of Shawang gold deposit in Haiyang of Shandong

Shawang gold deposit is a large gold deposit, located in the NE margin of the Jiaolai basin, which is part of Muping-Jimo metallogenic belt in eastern Shandong. It was controlled by the footwall of Guocheng fault zone and secondary faults zone. Aiming to the fluid inclusions in Shawang gold deposit, the authors carry on petrographic, microthermometric and Raman spectroscopic component analyses. The results show that there are four-type fluid inclusions： single phase inclusions, gas-liquid two-phase inclusions, pure CO2 inclusions and three-phase inclusions containing CO2. Ore-forming fluid is characterized by low salinity （4.3%-12.6% NaC1. eqv）, low density （0.64-0.97 g/cm3 ）, medium-high temperature （280℃-320℃）, metallogenic pressure with 81-94 MPa, and metallogenic depth as 7.39-7.98 kin. The fluid experienced immiscibility of CO2-NaCl- H2O system during the metallogenic process. In combination with the analysis of hydrogen and oxygen isotopes in fluid inclusions, it is determined that the Shawang gold deposit is mesothermal vein-type, with participation of mantle-derived water and magmatic water for its genesis.

Scanning Raman Picoscopy: Angstrom-Resolved Tip-Enhanced Raman Spectromicroscopy

In this review,we present a brief overview on the recent advances in Angstr6m-resolved tip-enhanced Raman spectromicroscopy.We first introduce the theoretical understanding of the confinement of light at the atomistic scale,and explain how the Raman scattering from a single molecule happens under the“illumination”of such an atomically confined light.Then we describe the latest developments on Angstr6m-resolved tipenhanced Raman spectromicroscopy,particularly on a new methodology called“scanning Raman picoscopy”for visually cons true ting the chemical st ruc ture of a single molecule in real space.Finally,we give a perspective of this technique in various applications where iden ti fying the chemical st ruc tu res of mat erials at the chemical bond level is required.

多光谱成像技术分析彩色艺术品的相关基础研究

多光谱成像技术集数字成像和光谱测量技术于一体,是一种记录光学信息的新型无损分析技术。基于对国内外文化遗产领域多光谱成像技术研究现状的分析,使用自行搭建的多光谱成像系统对敦煌壁画颜料模拟试板和现代国画在300~1000 nm范围内进行光谱图像采集,检验多光谱成像系统的适用性。结果显示多光谱图像能对外观相近的不同颜料做出快速区别,结合激光显微拉曼光谱技术,可进一步识别样品中颜料的种类;同时,多光谱图像还能够揭示具有紫外激发可见荧光特性的物质分布、画稿中的底稿信息、水渍痕迹等信息。实验表明多光谱成像技术可以有效获取彩色艺术品的多样化信息,在彩色艺术品研究领域具有良好的应用前景。

Radiation induced graft polymerization of multi-walled carbon nanotubes for superhydrophobic composite membrane preparation

Highly soluble multi-walled carbon nanotubes （MWNTs） were prepared by radiation-induced free radical graft polymerization of vinyl acetate （VAc） onto pristine MWNT surfaces. High resolution transmission electron microscopy （HR-TEM）, Fourier transform infrared （FT1R） spectroscopy, and micro-Raman spectroscopy were used to confirm that poly（vinyl acetate） （PVAc） had been successfully grafted onto the surface of the MWNTs. The effects of experimental parameters on the degree of graft- ing （DG） of PVAc were also investigated, including adsorbed dose, dose rate, initial monomer concentration, and solvents. The grafted MWNTs （MWNTs-g-PVAc） exhibited good solubility in common organic solvents at high mass fraction. In addition, a superhydrophobic composite membrane could be readily fabricated by vacuum filtration of MWNTs-g-PVAc onto a support- ing membrane, as was confirmed by water contact angle testing and visualization by scanning electron microscopy.

Complete thermoelectric benchmarking of individual InSb nanowires using combined micro-Raman and electric transport analysis

Nanowires （NWs） are ideal nanostructures for exploring the effects of low dimensionality and thermal conductivity suppression on thermoelectric behavior. However, it is challenging to accurately measure temperature gradients and heat flow in such systems. Here, using a combination of spatially resolved Raman spectroscopy and transport measurements, we determine all the thermoelectric properties of single Se-doped InSb NWs and quantify the figure of merit ZT. The measured laser-induced heating in the NWs and associated electrical response are well described by a 1D heat equation model. Our method allows the determination of the thermal contact resistances at the source and drain electrodes of the NW, which are negligible in our system. The measured thermoelectric parameters of InSb NWs agree well with those obtained based on field-effect transistor Seebeck measurements.

Arc corrosion behavior of Cu-Ti_3AlC_2 composites in air atmosphere

The arc corrosion evolution of Cu-20 vol.% Ti_3 AlC_2 cathodes is presented here. After eroded by 3, 4, 5, 6, 7, 8, 9, 10 kV DC voltage, respectively, the surface morphologies were characterized by field emission scanning electron microscope with craters and protrusions. Compared to small craters and dense protrusions of the morphology by high voltage, the eroded surface was covered with bigger craters and sparse protrusions at low voltage. No crack was discovered on the surface even at 10 kV. By means of energy dispersive spectroscopy and Raman spectroscopy, the decomposition of Cu-20 vol.% Ti_3 AlC_2 cathode to CuO,Al__2 O_3 and TiO_2 were proved. Meanwhile, W anode is oxidized to WO_2. The peak current increases with the increasing breakdown voltage, which is recorded by a digital memory oscilloscope.

Proton irradiation effects on HVPE GaN

GaNs grown by hydride vapor phase epitaxy(HVPE) were irradiated by protons with different fluences.The changes of surface topography of as-grown and irradiated samples were characterized by atomic force microscopy(AFM).The crystal quality and optical properties of GaN films were examined by the variations of the micro-Raman and photoluminescence(PL) spectra with proton fluence.It was observed that the surface became a little more rough after irradiation.The Raman spectra indicated that the strain of materials and carrier concentration were not affected by the proton injection.The full-width at half-maximum(FWHM) of E 2 high phonon mode narrowed,which was consistent with the FWHM of PL near-band-edge emission(BE).The spectra of yellow luminescence and blue luminescence normalized to the intensity of BE demonstrated a little increase of Ga vacancy and a large decrease of O N,which may be the main reason for the change of optical properties.

Laser induced oxidation and optical properties of stoichiometric and non-stoichiometric Bi2Te3 nanoplates

Bi-Te nanoplates （NPs） grown by a low pressure vapor transport method have been studied by Raman spectroscopy, atomic force microscopy （AFM）, energy- dispersive X-ray spectroscopy （EDS）, and Auger electron spectroscopy （AES）. We find that the surface of relatively thick （more than tens of nanometers） Bi2Te3 NPs is oxidized in the air and forms a bump under heating with moderate laser power, as revealed by the emergence of Raman lines characteristic of Bi2O3 and TeO2 and characterization by AFM and EDS. Further increase of laser power burns holes on the surface of the NPs. Thin （thicknesses less than 20 nm） NPs with stoichiometry different from Bi2Te3 were also studied. Raman lines from non-stoichiometric NPs are different from those of stoichiometric ones and display characteristic changes with the increase of Bi concentration. Thin NPs with the same thickness but different stoichiometries show different color contrast compared to the substrate in the optical image. This indicates that the optical absorption coefficient in thin Bi-Te NPs strongly depends on their stoichiometry.

Structure and magneto-electrical properties of Fe-C films prepared by magnetron sputtering

Fe-doped amorphous FexCl~ granular films were prepared on n-Si （100） substrates by d.c. magnetron sputtering. The structur- al properties of FexC1-x films were investigated by X-ray diffraction （XRD）, atomic force microscope （AFM） and Raman spec- troscopy. The results show that the iron and carbon of as-deposited films are in amorphous state, and the FexC1-x films are di- amond-like carbon （DLC） films. After doping iron into the DLC films, a smooth surface morphology of the FexC1-x films has been obtained with the surface roughness Ra of about 0.231 nm for x=18at%. The FexC1-x films have good soft magnetic prop- erties with the coercivity of approximately 20 Oe. A high positive magnetoresistance （MR） up to 93% with x=lat% was ob- served in a FexCl-x granular film at 300 K. The resistance characteristic of Fe-C films is changed at about 230 K and the positive MR effect can be understood by the p-n heterojunction theory.

Separation of Gold Nanorods Using Density Gradient Ultracentrifugation

High quality gold nanorods （NRs） with a monodisperse size and aspect ratio are essential for many applications. Here, we describe how nearly monodisperse gold NRs can be separated from polydisperse samples using density gradient ultracentrifugation. Size and dimension analysis by transmission electron microscopy （TEM） and absorption spectroscopy revealed that the Au NRs were separated mainly as a function of their aspect ratio The surface-enhanced Raman scattering （SERS） activity of Au NRs with lower aspect ratio is notably stronger than that of NRs with higher aspect ratio under 633 nm laser excitation, due to the size-dependent absorption of the longitudinal plasmon band. The separation approach provides a method to improve the quality of NRs produced by large scale synthetic methods.

Kinetics of defect formation in chemically vapor deposited （CVD） graphene during laser irradiation： The case of Raman investigation

The effect of laser irradiation on chemically vapor deposited （CVD） graphene was studied by analyzing the temporal evolution of Raman spectra acquired under various illumination conditions. The spectra showed that the normalized intensity of the defect-related peak increases with the square root of the exposure time and varies almost linearly with the laser power density. Furthermore, the hardness of graphene to radiation damage depends on its intrinsic structural quality. The results suggest that, contrary to the common belief, micro-Raman spectroscopy cannot be considered a noninvasive tool for the characterization of graphene. The experimental observations are compatible with a model that we derived from the interpretative approach of the Staebler-Wronski effect in hydrogenated amorphous silicon; this approach assumes that the recombination of photoexcited carriers induces the breaking of weak C-C bonds.

Evolution of the Raman spectrum of graphene grown on copper upon oxidation of the substrate

Significant changes in the Raman spectrum of single-layer graphene grown on a copper film were observed after the spontaneous oxidation of the underlying substrate that occurred under ambient conditions. The frequencies of the graphene G and 2D Raman modes were found to undergo red shifts, while the intensities of the two bands change by more than an order of magnitude. To understand the origin of these effects, we further characterized the samples by scanning tunneling microscopy （STM）, scanning tunneling spectroscopy （STS）, and atomic force microscopy （AFM）. The oxidation of the substrate produced an appreciable corrugation in the substrate without disrupting the crystalline order of the graphene overlayer and/or changing the carrier doping level. We explain the red shifts of the Raman frequencies in terms of tensile strain induced by corrugation of the graphene layer. The changes in Raman intensity with oxidation arise from the influence of the thin cuprous oxide film on the efficiency of light coupling with the graphene layer in the Raman scattering process.

Preparation of nano-porous AlN micro-rods

In this paper, nano-porous A1N micro-rods were prepared and characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, Brunauer-Emett-Teller （BET） method of nitrogen adsorption at low temperature, UV-via absorption spectrometry and Raman spectrometry. The SEM images and TEM images showed that the A1N samples were micro-size rods with pores in their surfaces evenly. The length of the rod was in the range of a few mi- crons to tens of micron, the diameter of the rods was about one micron, the diameter of the pore was about hundreds of nano- meter and the wall thickness of the pore about tens of nanometer. The BET surface area of the sample was 41.424 ma/g. The optical spectra showed that the optical properties of the A1N samples almost agreed with that of A1N bulk or film.

Si@Cu@Au AFM tips for tip-enhanced Raman spectrum

Tip-enhanced Raman spectrum(TERS) is a scanning probe technique for acquiring chemical information at high spatial resolution and with high chemical sensitivity. The sensitivity of TERS with atomic force microscopy(AFM) system is mainly determined by the metalized tips. Here, we report a fabrication protocol for AFM-TERS tips that incorporate a copper(Cu) primer film between a gold(Au) layer and a Si AFM tip. They were fabricated by coating the Si tip with a 2 nm Cu layer prior to adding a 20 nm Au layer. For top illumination TERS experiments, these tips exhibited superior TERS performance relative to that observed for tips coated with Au only. Samples included graphene, thiophenol and brilliant cresyl blue. The results may derive from the surface roughness of the tip apex and a Cu/Au synergism of local surface plasmon resonances.

Electrochemical synthesis and the functionalization of few layer graphene in ionic liquid and redox ionic liquid

Electrochemical reductive exfoliation of graphite to few layered graphene(FLG) in presence of 1-ethyl-2,3-dimethyl imidazolium bis(trifluoromethylsulfonyl) imide ionic liquid and redox ionic liquid based ferrocene has been investigated. Thus, by applying a mild negative potential(-2.7 V vs. Fc/Fc^+) to carbon electrode in ionic liquid graphene flakes could be generated. The generated materials have been characterized by X-ray photoelectron spectroscopy, Raman spectroscopy, high resolution transmission electron microscopy and atomic force microscopy. XPS and Raman analysis show that the electrochemical reductive exfoliation provides the formation of FLG. The thickness of the resulting FLG was found to be ranged between 4 and1 nm. HR-TEM images reveal the formation of few graphene layers and in some cases single graphene layer was observed.Moreover, this electrochemical route conduces to the formation of ionic liquid functionalized FLG. Finally, the reductive exfoliation was further investigated in the presence of redox ionic liquid. XPS and electrochemical measurements confirm the presence of ferrocene.