用二维基及补充元计算RAMAN散射张量

用二维基及补充元计算ＲＡＭＡＮ散射张量郝伟，廖理几，金泽宸（北京工业大学应用物理系北京１０００２２）ＣａｌｃｕｌａｔｉｎｇＲａｍａｎｓｃａｔｔｅｒｉｎｇｔｅｎｓｏｒｓｂｙ２－ｄｉｍｅｎｓｉｏｎａｌｂａｓｅｓａｎｄａｄｄｉｔｉｏｎａｌｏｐｅｒａｔｉｏｎ...

二维基波超声造影联合盆腔水造影评估输卵管伞端形态与功能的风险预测模型构建及验证

目的构建二维基波超声造影(2D-FS)联合盆腔水造影(SIPS)评估输卵管伞端形态与功能的风险预测模型,并进行验证。方法63例不孕症女性患者、126条输卵管,随机分为模型构建组(56例)和模型验证组(7例),结合患者病史及三维超声造影检查排除已切除或完全不通的输卵管,然后行2D-FS联合SIPS评估剩余输卵管伞端的形态与功能,并于6个月内接受腹腔镜直视下输卵管通染术(LDT)作为“金标准”。选取模型构建组数据,采用Logistic回归分析法筛选出伞端异常的超声诊断指标,构建风险预测模型并绘制受试者工作特征(ROC)曲线,分析该预测模型对验证组样本伞端的诊断效能。结果Logistic回归分析显示超声造影评价伞端异常的特征性危险因素为输卵管伞端指状突起的宽径(χ2)、回声(χ3)、活动度(χ4)、造影剂的溢出速度与形状(χ5),而输卵管伞端指状突起的数量(χ1)为保护因素。Logistic回归方程为y=-2.639-0.409χ1+1-763χ2+1.625χ3+1.955χ4+2.762χ5,超声造影预测模型预测输卵管伞端形态与功能的ROC曲线下面积(AUC)为0.902,敏感性及特异性分别为80.65%、97.87%。模型验证组的AUC为0.833,敏感性及特异性分别为96.89%、66.67%。结论2D-FS联合SIPS评价输卵管伞端形态与功能的风险预测模型具有较高的应用价值,可为临床选择治疗策略、判断手术预后提供客观依据。

快离子导体AgxTiS2中Ag^＋离子-空位的二维基态结构与能量性质研究

根据Ag+离子-空位的二维有序结构建立了三维晶胞模型.采用局域密度近似下的平面波赝势方法,对有序AgxTiS2(x=0,1/4,1/3,1/2,2/3,3/4,1)系列进行了几何结构优化和总能量计算,并与LixTiS2系列进行了对比研究.有序AgxTiS2系统的晶格参量增量Δa0和Δc0随离子浓度单调增加,与实验结果符合得较好.有序AgxTiS2和LixTiS2系统的总能量均随插层离子浓度增加线性下降,且前者下降较快.有序AgxTiS2(x=0,1/4,1/3,1/2,2/3,3/4,1)系统的形成能均小于零,表明其基态性质.具有3a0×3a0超结构的Ag1/3TiS2系统的形成能最低.能量性质的对比显示,有序AgxTiS2系统的形成能较低,有序-无序相变温度较高,离子扩散活化能较高.根据计算结果对有关实验给出了合理解释.

Optimization of Plasma Etching Parameters and Mask for Silica Optical Waveguides

Optical waveguides in silica-on-silicon are one of the key elements in optical communications.The processes of deep etching silica waveguides using resist and metal masks in RIE plasma are investigated.The etching responses,including etching rate and selectivity as functions of variation of parameters,are modeled with a 3D neural network.A novel resist/metal combined mask that can overcome the single-layer masks’ limitations is developed for enhancing the waveguides deep etching and low-loss optical waveguides are fabricated at last.

Hydroxyl radicals-mediated oxidative cleavage of the glycosidic bond in cellobiose by copper catalysts and its application to low-temperature depolymerization of cellulose

As the most abundant source of biomass in nature for sustainable production of fuels and chemicals,efficient depolymerization of cellulose under mild conditions,due to the difficulty in selective cleavage of itsβ-1,4-glycosidic bonds,still remains challenging.Here,we report a novel method for oxidative cleavage of the glycosidic bonds by free radicals.Probed by the cellobiose reaction,it was found that·OH radicals,generated from the decomposition of H2O2 catalyzed by CuSO4 or CuO/SiO2,were efficient for selective conversion of cellobiose to glucose and gluconic acid at a low temperature of 333 K,and their selectivities reached 30.0%and 34.6%,respectively,at 23.4%cellobiose conversion.Other radicals,such as·SO4?,also exhibited high efficacy in the cellobiose reaction.Mechanistic studies suggest that the oxidative cleavage of theβ-1,4-glycosidic bond by the free radicals involve formation of the carbon radical intermediate via abstraction of the H atom dominantly at the C1 position.Following this oxidative mechanism,treatment of microcrystalline cellulose with·OH by impregnation with H2O2 and CuSO4 catalyst at 343 K led to significant enhancement in its hydrolysis efficiency.These results demonstrate the effectiveness of this new method in the oxidative cleavage of glycosidic bonds,and its viability for the efficient depolymerization of cellulose at low temperatures,which can be further improved,for example,by exploring new free radicals and optimizing their reactivity and selectivity.

Collapse Analysis of Imperfect Subsea Pipelines Based on 2D High-Order Nonlinear Model

To study the collapse of imperfect subsea pipelinos, a 2D high-order nonlinear model is developed. In this model, the large deformation of the pipes is considered by raiaining the high-order nonlinear terms of strain. In addi-tion, the J2 plastic flow theory is adopted to describe the elasioplastic constitutive relations of material. The quasi-static process of collapse is analyzed by the increment method. For each load step, the equations based on the principle of virtual work are presented and solved by the discrete Newton＇s method. Furthermore, finite element simulations and full-scale experiments were preformed to validate the results of the model. Research on the major influencing factors of collapse pressure, including D/t, material type and initial ovality, is also presented.

Construction of 2D Zn‐MOF/BiVO_(4)S‐scheme heterojunction for efficient photocatalytic CO_(2) conversion under visible light irradiation

The construction of S‐scheme heterojunction photocatalysts has been regarded as an effective avenue to facilitate the conversion of solar energy to fuel.However,there are still considerable challenges with regard to efficient charge transfer,the abundance of catalytic sites,and extended light absorption.Herein,an S‐scheme heterojunction of 2D/2D zinc porphyrin‐based metal‐organic frameworks/BiVO_(4)nanosheets(Zn‐MOF/BVON)was fabricated for efficient photocatalytic CO_(2)conversion.The optimal one shows a 22‐fold photoactivity enhancement when compared to the previously reported BiVO4 nanoflake(ca.15 nm),and even exhibits~2‐time improvement than the traditional g‐C3N4/BiVO4 heterojunction.The excellent photoactivities are ascribed to the strengthened S‐scheme charge transfer and separation,promoted CO_(2)activation by the well‐dispersed metal nodes Zn_(2)(COO)_(4)in the Zn‐MOF,and extended visible light response range based on the results of the electrochemical reduction,electron paramagnetic resonance,and in‐situ diffuse reflectance infrared Fourier transform spectroscopy.The dimension‐matched Zn‐MOF/BVON S‐scheme heterojunction endowed with highly efficient charge separation and abundant catalytic active sites contributed to the superior CO2 conversion.This study offers a facile strategy for constructing S‐scheme heterojunctions involving porphyrin‐based MOFs for solar fuel production.

Upregulation of TNF-α mRNA in hepatic fibrosis rats induced by dimethylnitrosamine

Objective:To observe the expression level of TNF-α mRNA in rats with hepatic fibrosis induced by dimethylnitrosamine (DMN) and to explore its relationship with collagen metabolism and its diagnostic value for hepatic fibrosis.Methods: Twenty-five male Wistar rats were randomly divided into normal control group (n=10) and model group (n=15). Model rats were induced by DMN for 4 weeks and at final stage were executed. TNF-α mRNA were detected by RT-PCR and the inflammatory necrosis and collagen deposition in hepatic tissue were observed by HE stain and Sirius red stain. The liver functions were determined by automatic biochemical analytic device. The serum marks of liver fibrosis, such as HA, LN and Ⅳ-C were measured with ELISA and RIA. Results: In this study, the rat model of liver fibrosis induced by DMN was successfully constructed. RT-PCR reveals that TNF-α mRNA expression in control group is lower than that of model group. The liver functions of model group were impaired compared with those of the control group (P<0.01). Semi-quantitive analysis revealed that TNF-α/β-actin of normal rats was 0.39±0.12, while 0.93±0.05 of model rats. The concentration of HA (434.44±98.81 vs 252.9±26.59 ng/ml, P<0.01), LN (70.67±6.32 vs 37.90±5.97 ng/ml, P<0.01) and Ⅳ-C (79.39±10.52 vs 21.40±4.17 ng/ml, P<0.01) were significantly increased in the model group as well. Changes of the indexes were similar to the pathological damage of the liver. Conclusion: The results suggested that activation of TNF-α in liver tissues may be the common pathogenic mechanism of liver fibrosis. TNF-α may be a useful index for the diagnosis of hepatic fibrosis which worthies further investigation.

Processing and properties of 2D SiC/SiC composites by precursor infiltration and pyrolysis

Two-dimensional plain-weave silicon carbide fiber fabric reinforced silicon carbide(2D-SiC/SiC)composites were molded by stacking method and densified through precursor infiltration and pyrolysis(PIP)process.SiC coating was deposited as the fiber/matrix interphase layer by chemical vapor deposition(CVD)technique.Fiber/matrix debonding and relatively long fiber pullouts were observed on the fracture surfaces.Additionally,the flexural strength and elastic modulus of the composites with and without fiber/matrix interphase layer were investigated using three-point bending test and single-edge notched beam test.The results show that the fiber fraction and the porosity of 2D-SiC/SiC composites with and without coating are 27.2%(volume fraction)and 11.1%,and 40.7%(volume fraction)and 7.5%,respectively.And the flexural strength and elastic modulus of 2D-SiC/SiC composites with and without coating are 363.3 MPa and 127.8 GPa,and 180.2 MPa and 97.2 GPa,respectively.With a proper thickness,the coating can effectively adjust the fiber/matrix interface,thus causing a dramatic increase in the mechanical properties of the composites.

Flotation separation of quartz from magnesite using carboxymethyl cellulose as depressant

Carboxymethyl cellulose(CMC)was introduced as a depressant in reverse flotation separation of quartz from magnesite.The flotation behavior and surface properties of magnesite and quartz exposed to CMC were studied by zeta potential tests,atomic force microscopy imaging and contact angle measurements.The addition of CMC as the depressant in reverse flotation using dodecylamine(DDA)as the collector exhibited a selectively depressive performance towards magnesite and achieved an improved recovery of magnesite.The study of surface properties demonstrated that CMC and DDA exhibited different adsorption strengths on the surface of magnesite and quartz.It was found that the adsorption of CMC on magnesite surface was stronger than that of DDA,which hindered the subsequent adsorption of DDA on magnesite surface.On the contrary,the quartz surface was strongly adsorbed by DDA instead of CMC,which proved that the addition of CMC did not influence the flotation of quartz.

Nanoencapsulation of Lutein with Hydroxypropylmethyl Cellulose Phthalate by Supercritical Anfisolvent

Lutein was nano-encapsuled with hydroxypropylmethyl cellulose phthalate （HPMCP） to maintain its bioactivity and to avoid thermal/light degradation. Supercritical antisolvent precipitation was applied to prepare lutein/HPMCP nano-capsule. The effects of several operating parameters on the yield, lutein loading, encapsulation efficiency, particle size and particle size distribution of the nanocapsule were investigated. The mean diameter of nanocapsules ranged from 163 nm to 219 nm under appropriate experimental conditions. The result of scanning electron microscope showed that the nanocapsules were nearly spherical. The highest yield reached 95.35% when the initial concentration of lutein was saturated. The highest lutein loading of 15.80% and encapsulation efficiency of 88,41% were obtained under the conditions of 11 MPa, 40℃ and CHPMCP： Clutein= 5：1. The results may promote the application of lutein in food industry.

Iron deposition and fat accumulation in dimethylnitrosamine-induced liver fibrosis in rat

AIM： To investigate if iron deposition and fat accumulation in the liver play a pathogenetic role in dimethylnitrosamine （DMN）-induced liver fibrosis in rat.METHODS： Thirty rats were treated with DMN at does consecutive days of 10 μL/kg daily, i.p., for 3 consecutive day each week for 4 wk. Rats （n = 30） were sacrificed on the first day （model group A） and 21st d （model group B） after cessation of DMN injection. The control group （n = 10） received an equivalent amount of saline. Liver tissues were stained with hematoxylin ＆ eosin （HE） and Masson and Prussian blue assay and oberserved under electron microscopy. Serum alanine aminotransferase （ALT）and liver tissue hydroxyproline （Hyp） content were tested.RESULTS： The liver fibrosis did not automaticallyreverse, which was similar to previous reports, the perilobular deposition of iron accompanied with collagen showed marked characteristics at both the first and 21st d after cessation of DMN injection. However, fat accumulation in hepatocytes occurred only at the 21^st d after cessation of DMN injection.CONCLUSION： Iron deposition and fat accumulation may play important roles in pathological changes in DMN-induced rat liver fibrosis. The detailed mechanisms of these characteristics need further research.

PREPARATION OF UREA NITROGEN ADSORBENT OF COMPLEX TYPE AND ADSORPTION CAPACITY OF UREA NITROGEN ONTO THE ADSORBENT

The urea nitrogen adsorbent of complex type, which consists of chitosan coated dialdehyde cellulose （CDAC） and immobilized urease in gelatin membrane （IE）, was prepared. The cellulose, the dialdehyde cellulose （DAC） and the CDAC were characterized by scanning electronic microscope. The results indicate that the cellulose C2-C3 bond was broken under the oxidation of periodate and it was oxidated to DAC. The DAC was coated with chitosan and the CDAC was obtained. The adsorption of urea nitrogen onto the adsorbent in Na2HPO4-NaH2PO4 buffer solution was studied in batch system. The effects of the experiment parameters, including degree of oxidation of CDAC, initial urea nitrogen concentration, pH and temperature, on the adsorption capacity of urea nitrogen onto the adsorbent at CDAC/IE weight ratio 10：1 were investigated. The results indicate that these parameters affected significantly the adsorption capacity. The adsorption capacity of urea nitrogen onto the adsorbent was 36.7 mg/g at the degree of oxidation of CDAC 88%, initial urea nitrogen concentration 600 mg/L, pH 7.4 and temperature 37℃.

Design of observer-based discrete repetitive-control system based on 2D model

A discrete observer-based repetitive control(RC) design method for a linear system with uncertainties was presented based on two-dimensional(2D) system theory. Firstly, a 2D discrete model was established to describe both the control behavior within a repetition period and the learning process taking place between periods. Next, by converting the designing problem of repetitive controller into one of the feedback gains of reconstructed variables, the stable condition was obtained through linear matrix inequality(LMI) and also the gain coefficient of repetitive system. Numerical simulation shows an exceptional feasibility of this proposal with remarkable robustness and tracking speed.

Two-Dimensional Infrared Spectroscopy of the Photoproduct of π-Cyclopentadienyliron Dicarbonyl Dimer

Equilibrium photoproduct of 7r-cyclopentadienyliron dicarbonyl dimer [CpFe（CO）2]2 in non- polar solvent carbon tetrachloride （CC14） is investigated using time-resolved 2D IR spec- troscopy. One of the several possible visible-light-driven photoreaction pathways is confirmed and the product is found to contain a di-carbonyl group that exhibits quantum beating be- tween two equivalent transitions in time-resolved 2D IR spectra, which turns out to be the anti-symmetric and symmetric stretching of the terminal carbonyl stretching modes of CpFe（CO）2C1. This is the main product and its reaction pathway involves radical formation, followed by chloride addition. Quantum-chemistry computations support these experimental results. Our results indicate that 2D IR method can be used to identify in situ structures and dynamics of chemical species involved in condensed-phase chemical reactions.

Decomposition of Cellulose to Produce 5-Hydroxymethyl-Furaldehyde in Subcritical Water

A method for decomposition of cellulose to produce 5-hydroxymethyl-furaldehyde （5- HMF） in subcritical water-carbon dioxide binary system was proposed. A series of experiments were performed in a batch reaction vessel. Main products of the decomposition of cellulose are 5-HMF, furfural, levulinic acid and 1, 2, 4-benzenetrioI.The optimum condition for the preparation of 5-HMF was found as 523.15 K, 5.0% carbon dioxide mole fraction, and 30 min reaction time. The addition of carbon dioxide to water conduced to the decomposition of cellulose to 5-HMF. As can be seen from the distribution of the prod-ucts, the decomposition mechanism of cellulose is similar to the hydrothermal reaction of D-glucose and D-fructose.

A Study of Soil-dynamics Based on a Simulated Drought in an Alpine Meadow on the Tibetan Plateau

Extreme weather events have played an important role in driving the ecosystem dynamics in high altitude areas, but the underlying mechanism remains unclear. To understand if and how the soil processes of an ecosystem react to extreme drought, we manipulated a once-in-a-century meteorological extreme drought in an alpine meadow on the Tibetan Plateau, which is also known as the ＂forerunner of global weather changes＂. The extremity was determined by statistical extreme weather events with respect to a historical reference period from April to September during 1962 - 2004, where the local historical precipitation data was calculated and intensified to loo-year recurrent drought event with Gumbel I distribution. The indicators we measured included soil microbial biomass C/N/P and soil enzymatic activities of phosphatase （AP） disbounding organic phosphate, cellobiohydrolase （CBH）, β- glucocidase （BG）, N-releasing enzyme N-acetyl- glucosaminidase （NAG） as well as soil respirations, during and after the treatments. It was found that the manipulated event induced a rapid shift in microbial biomass and activities, indicating a lower resistance of the underground process. However, the microbial and biochemical parameters saw rapid recovery after the event, which meant the soil processes enjoyed high resilience. The high responsiveness and lag-time effects of the soil indicators rendered new horizons for us to evaluate the interaction between the extremes and the ecosystem stability. Our study indicated that the once-in-a-century extreme drought induced very short term response in the soil biotic process, and the soil processes worked to buffer against such events under the observation period.

A Note on Casoratian Solutions to Two-Dimensional Toda Lattice

In this short paper we generalize the conditions that Casoratian entries satisfy for the two-dlmenslonal Toda lattice. Although we finally conclude that our generalization is trivial in some sense for getting new solutions, our discussion is still helpful for the study of Wronskian technique.

Magnetic Solid-Phase Extraction of Phthalate Esters from Environmental Water Samples using Fibrous Phenyl-functionalized Fe3O4@SiO2@KCC-1

A new kind of phenyl-functionalized magnetic fibrous mesoporous silica(Fe3 O4@Si O2@KCC-1-phenyl) was prepared by copolymerization as an efficient adsorbent for the magnetic extraction of phthalate esters from environmental water samples. The obtained Fe3 O4@Si O2@KCC-1-phenyl showed monodisperse fibrous spherical morphology, fairly strong magnetic response(29 emu/g), and an abundant π-electron system, which allowed rapid isolation of the Fe3 O4@Si O2@KCC-1-phenyl from solutions upon applying an appropriate magnetic field. Several variables that affect the extraction efficiency of the analytes,including the type of the elution solvent, amount of adsorbent, extraction time and reusability, were investigated and optimized. Under optimum conditions, the Fe3 O4@Si O2@KCC-1-phenyl was used for the extraction of four phthalate esters from environmental water samples followed by high-performance liquid chromatographic analysis. Validation experiments indicated that the developed method presented good linearity(0.1-20 ng/m L), low limit of detection(7.5-29 μg/L, S/N =3). The proposed method was applied to the determination of phthalate esters in different real water samples, with relative recoveries of 93%-103.4%and relative standard deviation of 0.8%-8.3%.

Allium sativum Flavor Compounds as an Indicator for Garlic Identity and Quality Determination

The objective of the study was to research the aroma profile of volatile compounds in garlic subspecies originating from Latvia, and compare them with the aroma composition of garlic grown in the region of Midi-Pyrenees （France）. It was established that hard-neck garlic tends to contain more diallyl disulfide （DADS）, the main decomposition product of allicin. Compared to the hard-neck subspecies, the content of allyl mercaptan, one of the major compounds producing the strong odor detectable after ingestion of garlic, was significantly lower in the soft-neck garlic clones. The amount of cyclic compound 3-vinyl-1,2-dithiin differed considerably with higher contents in the soft-neck subspecies. The results also demonstrate the soft-neck garlic as a more suitable subspecies for long-term storage. In general, the results show no significant difference in the content of DADS and the total content of other flavor compounds between hard-neck and soft-neck garlic grown in the region of Midi-Pyrenees and Latvia. However, comparing garlic subspecies originating from France and Latvia by the content of allyl mercaptan, 1,2-dithiolane and 3-vinyl-1,2-dithiin, a considerable proportional difference of these volatiles was determined. Also, a significant difference was established in the content of DADS between the white garlic variety ＂Blanc de Lomagne＂ （France, region of Midi-Pyrenees） and white garlic grown in other countries. The results of this study suggest the suitability of solid phase microextraction （SPME） and gas chromatography （GC） methods for quality control of garlic originating from France.