典型表活剂与稠油在蒙脱石表面吸附行为的分子动力学模拟

为探究蒸汽与表面活性剂复合驱对稠油与黏土矿物表面吸附稳定性的影响，建立表活剂溶液、稠油和蒙脱石的三元吸附体系，采用分子动力学方法阐释稠油与表活剂在蒙脱石表面的微观竞争吸附机理。计算结果表明：非离子型表活剂难以与蒙脱石表面接触，但在高温吸附质环境中具有较强的扩散能力；阳离子型表活剂在较低温度下占据蒙脱石表面吸附位点并使稠油分子脱离蒙脱石；而阴离子表活剂在高温条件下容易使稠油分子远离蒙脱石。高温促使沥青质聚集核离散，从而促进稠油的流动，但会导致部分表活剂更加亲附蒙脱石而造成非必要的损失。本研究为合理调整温度与表活剂的匹配性，为敏感性稠油油藏的开发提供了良好的应用前景及推广意义。     

九江网纹红土中粘土矿物过渡相的矿物学特征及成因

为研究长江中下游网纹红土中粘土矿物过渡相的矿物学特征及成因,采用X射线衍射(XRD)、傅里叶红外吸收光谱(FTIR)、以及高分辨透射电子显微分析(HRTEM)等现代测试技术方法,对江西九江红土剖面网纹红土中粘土矿物过渡相开展系统、深入的研究。X射线衍射及红外吸收光谱分析结果表明,九江剖面网纹红土中粘土矿物组成主要有伊利石和高岭石,少量蒙脱石和伊利石/蒙脱石及微量高岭石/蒙脱石混层矿物过渡相。在高分辨透射电子显微镜下,可观察到蒙脱石晶层向高岭石晶层转化的现象。伊利石/蒙脱石过渡相是伊利石向蒙脱石转化的过渡产物,而高岭石/蒙脱石过渡相则为蒙脱石向高岭石转化的过渡产物,网纹红土中这两种过渡相的出现说明了粘土矿物风化演化的过程,即：伊利石→伊利石/蒙脱石混层矿物→蒙脱石→高岭石/蒙脱石混层矿物→高岭石的演化,同时表明网纹红土形成于风化作用增强的温暖潮湿气候环境。     

利用X射线近边吸收谱学方法研究蒙脱石在高温下吸附汞金属的行为

测量了分别用汞水溶液、汞和半胱氨酸混合溶液处理的蒙脱石样品在高温下汞L₃边X射线近边吸收谱. 利用这个方法研究了汞金属在蒙脱石中的吸附和解吸附行为以及氨基酸对吸附汞吸附行为的影响. 研究结果显示在没有氨基酸介入的情况下,蒙脱石中吸附的汞被6个水分子配位,或者被蒙脱石表面的氧原子配位;当引入半胱氨酸时,汞优先于氨基酸中的硫原子配位,形成更稳定的Hg-S键. 这个结果说明氨基酸的引入能够使得蒙脱石更稳定的吸附汞金属离子,大大缓解汞离子向生物圈中迁移.     

锗在高压下固化时的相演化及动力学成因

 报道了锗在高压下固化时亚稳相的形成和转化。通过原位观测锗在高压下固化过程中的电阻变化、差热信号，并结合X射线衍射分析，详细讨论了锗在高压下固化时的相演化行为。在我们所进行的实验条件下，当压力大于4 GPa时，熔态锗首先固化成金属锗，然后再向GeⅠ或GeⅢ相转变。还讨论了压力对锗的固化动力学参数的影响。     

水在蒙脱石中的吸附与脱除

利用程序升温脱水——色谱检测(TPD-GC),并配合使用热重分析(TGA),差热分析(DTA)和X射线衍射(XRD)研究手段,系统地考察了一组金属离子交换蒙脱石中水的吸附与脱除.实验结果表明,蒙脱石中吸附水的存在状态和数量均明显地依赖于蒙脱石层间可交换金属离子的数目和水合能力.但是,与通常的理解不同,在任何一种离子交换蒙脱石中,这种吸附水都不可能有与蒙脱石间结合力明显不同的两种存在状态. 关键词：     

X射线衍射法定量分析蒙脱石中的α-SiO_2

矿物药蒙脱石(Montmorillonite)是一种硅铝酸盐复合物,由于其特殊的结构,所得到的蒙脱石或多或少的含有α-SiO_2,传统物理化学分析方法只能得到蒙脱石中总的二氧化硅含量,无法得到游离二氧化硅的含量。应用X射线衍射作为现代分析手段,基于待测物相的质量百分含量与该物相在样品中的X射线衍射强度成线性的原理,可确切给出混合物的物相和物相的含量。本文使用此方法快速、方便地测定了蒙脱石中的α-SiO_2含量。     

粘土矿物参与微生物利用木质素形成矿物-菌体残留物的结构特征研究

粘土矿物在催化木质素形成腐殖质方面具有重要贡献。为有效阐明微生物-木质素-粘土矿物三者间的关系，探明矿物-菌体残留物的结构特征，采用液体摇瓶培养法，以木质素为碳源，通过添加高岭石和蒙脱石，在接种复合菌剂后启动110 d液体培养，期间动态收集矿物-菌体残留物，利用傅里叶红外光谱及扫描电子显微镜技术对其结构特性进行了研究。结果表明：高岭石颗粒边缘多由管状体卷曲而成，在参与微生物利用木质素形成矿物-菌体残留物后，连片状细小颗粒结构进一步团聚，结合更加紧凑，短管状结构增多，但整体仍保持多水高岭石的结构特征；在初始富营养条件下，高岭石能够促进微生物繁衍，使大量菌体聚集于高岭石表面，掩蔽了Si-O和Si-O-Al键，且矿物-菌体残留物中脂族碳结构比例增加；菌体中多糖物质通过含氧官能团与高岭石表面的水化层在多个部位形成氢键，氢键的形成对于高岭石稳定木质素及其降解产物具有重要作用，芳香碳结构比例和多糖类物质含量随培养时间逐渐增加，而后复合菌株对掩蔽在矿物表面的菌体进行二次利用，使高岭石Si-O-Al键重现；蒙脱石多由浑圆的颗粒结构组成，接种微生物可使其表面产生溶蚀，团粒结构遭到破碎；与10 d相比，历经30 d培养所得矿物-菌体残留物中的多糖类物质增多，使原本归属蒙脱石Si-O-Si及Si-O结构的1 034~1 038 cm-1处吸收峰强度增加，而后因多糖类物质与蒙脱石表面羟基发生缔合，又使该处吸收峰强度减弱，同时发生了氢键键合，该作用是蒙脱石-微生物-木质素间相互作用、形成矿物-菌体残留物的主要机制；高岭石在稳定有机碳方面的能力要高于蒙脱石，更易促进HS前体物质的形成。     

高温下钙蒙脱石膨胀特性的分子动力学模拟

高温下蒙脱石的膨胀特性在核废料深部封存、二氧化碳封存及页岩气开发等应用中有着重要影响,但相关机理尚不明确.本工作使用分子动力学模拟为技术手段计算5 MPa和298—500 K等条件下,1.40—4.00 nm晶面间距(d)的一系列饱和钙蒙脱石的膨胀压力.以模拟所得的数值结果为依据,基于水化效应、双电层效应和离子关联效应等模型推演膨胀压力随温度与d的变化规律,并与相应的实验数据进行对比.模拟结果表明,当d较小时,因为高温会弱化水化力的强度,钙蒙脱石膨胀压力震荡的幅度降低,同时水化力作用的d的范围减小.当d较大时,因为高温强化离子关联效应,膨胀压力降低,同时双电层力的作用的d的范围增加.在较高温度和较大d时,膨胀压力为收缩力,阻碍膨胀.这些膨胀压力的变化规律与前期钠蒙脱石体系的研究类似.然而,通过对比两种蒙脱石体系的模拟结果,发现两种体系存在显著的差异—钙蒙脱石比钠蒙脱石更难膨胀到较大的d.此模拟结果与前人实验观测的结果相符.我们进一步将此差异归于钙蒙脱石的离子关联效应要远大于钠蒙脱石.有别于分子模拟中对于离子关联效应的精确描述,连续化的Poisson-Boltzmann方程因为忽略了离子关联效应,从而无法表达出与两种体系模拟结果都相吻合的膨胀压力变化规律.     

高温下钙蒙脱石膨胀特性的分子动力学模拟

高温下蒙脱石的膨胀特性在核废料深部封存、二氧化碳封存及页岩气开发等应用中有着重要影响,但相关机理尚不明确.本工作使用分子动力学模拟为技术手段计算5 MPa和298—500 K等条件下,1.40—4.00 nm晶面间距(d)的一系列饱和钙蒙脱石的膨胀压力.以模拟所得的数值结果为依据,基于水化效应、双电层效应和离子关联效应等模型推演膨胀压力随温度与d的变化规律,并与相应的实验数据进行对比.模拟结果表明,当d较小时,因为高温会弱化水化力的强度,钙蒙脱石膨胀压力震荡的幅度降低,同时水化力作用的d的范围减小.当d较大时,因为高温强化离子关联效应,膨胀压力降低,同时双电层力的作用的d的范围增加.在较高温度和较大d时,膨胀压力为收缩力,阻碍膨胀.这些膨胀压力的变化规律与前期钠蒙脱石体系的研究类似.然而,通过对比两种蒙脱石体系的模拟结果,发现两种体系存在显著的差异—钙蒙脱石比钠蒙脱石更难膨胀到较大的d.此模拟结果与前人实验观测的结果相符.我们进一步将此差异归于钙蒙脱石的离子关联效应要远大于钠蒙脱石.有别于分子模拟中对于离子关联效应的精确描述,连续化的Poisson-Boltzmann方程因为忽略了离子关联效应,从而无法表达出与两种体系模拟结果都相吻合的膨胀压力变化规律.     

聚氨酯改性TDE-85/ MeTHPA树脂的固化反应机理及动力学研究

 以聚醚二元醇、甲苯二异氰酸酯为原料，合成了聚醚型聚氨酯预聚体(PUP)。采用该预聚体、扩链剂1,4-丁二醇、交联剂三羟甲基丙烷对TDE-85/甲基四氢邻苯二甲酸酐（MeTHPA)环氧树脂体系进行改性，通过示差扫描量热法与红外光谱法分析，探讨了聚氨酯(PU)改性环氧树脂体系固化反应机理及固化反应动力学特征。固化反应机理研究表明，TDE-85与MeTHPA之间的固化反应形成环氧聚合物网络Ⅰ，1,4-丁二醇及三羟甲基丙烷同PUP进行了扩链、交联反应形成了PU聚合物Ⅱ。异氰酸酯基同环氧基反应，使得聚合物Ⅰ与聚合物Ⅱ形成了接枝化学键。固化反应动力学研究表明，PU的加入可明显降低环氧树脂固化反应的表观活化能，活化能由TDE-85/MeTHPA树脂体系时的83.14 kJ/mol降至PU改性后的67.91 kJ/mol。     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Hybrid Wavelength and Code Division Multiple Access in Optical Networks

A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.     

Single-beam self-referenced phase-sensitive surface plasmon resonance sensor with high detection resolution

A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques.     

Influences of SiO2 protective layers and annealing on the laser-induced damage threshold of Ta2O5 films

Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing.