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1.
According to the principles of simultaneous equilibrium and electronic charge neutrality, the thermodynamics of Zn（II）-NaOH-H2O system was studied in this paper. Varying the concentration of sodium hydroxide, in range of 0- 400 g/L, the distribution law of all zinc species and the mathematical model of equilibrium concentration of zinc in the system were obtained. The relative errors between theoretic calculation and the experimental values of total concentration of zinc were analyzed, and the absolute average error is only 0.129 8%. The mathematical model and the thermodynamic data are believable. 相似文献
2.
Ke Shao Jian-hua Yan Xiao-dong Li Sheng-yong Lu Mu-xing Fu Ying-lei Wei 《浙江大学学报(A卷英文版)》2010,11(5):363-369
The effects of SO2, SO3 on de novo synthesis of polychlorinated dibenzo-p-dioxins （PCDDs） and dibenzofurans （PCDFs） were studied using model fly ashes incorporating copper oxide and activated carbon. It was found that the inhibitive effect of SO2 on PCDD/Fs formation is similar to that of SO3. To investigate the inhibition mechanism, CuSO4 formations from both CuO and CuCl2 were examined. The ability of SO3 to convert CuCl2 and CuO on a silica support into sulfate is much stronger than that of SO2. However, replacing silica by activated carbon leads to a much high conversion of CuCl2 to CuSO4 in the presence of SO2. The promotion by activated carbon is explained by the reduction of CuCl2 to Cu2Cl2 and the eventual conversion of Cu2Cl2 into CuSO4 is the main inhibition mechanism of SO2 on de novo synthesis of PCDD/Fs. 相似文献
3.
采用溶胶——凝胶技术制备了壳聚糖/SiO2/CdS纳米复合材料作为固相微萃取膜,用该萃取膜与气相色谱联用测定环境水样中喹硫磷、甲基对硫磷、对硫磷、二嗪磷等有机磷农药残留。对固相微萃取条件,如萃取温度,萃取时间、萃取的pH值以及萃取时溶液中离子强度等因素进行了优化。在优化的实验条件下,各目标农药样品的检测线性范围为2.0~1000 ng/mL,检出限为1.0~1.7 ng/mL。样品加标回收率为81.13%~105.31%,相对标准偏差(RSD)为2.09%~3.71%。方法具有快速、简便、准确、重现性好的特点。 相似文献
4.
The coal tar was qualitative and quantitative anMyzed by gas chromatography （GC） method. 74 components were identified exactly by gas chromatographY-mass spectrometry （GC-MS）. 31 components （37%） were quantitatively analyzed by gas chromatography-flame ionization detector （GC-FID）. The linearity, accuracy, precision, limit of detection （LOD） and limit of quantitative （LOQ） determination were inspected. The scope of quantitative analysis by CC was discussed. The experimental results of thermogravimetric analysis （TGA） proved that GC quantitative analysis of the coal tar was reliable. 相似文献
5.
Oil spills may considerably damage sensitive coastal wetlands. The phytoremediation potential and restoration of a dominant coastal marsh plant, Cyperus rotundus, for diesel pollutant and its phytoremediation effectiveness were investigated in this open-air pot experiment. Cyperus rotundus was transplanted into soil contaminated with diesel at concentrations of 1 000, 5 000, 10 000, 15 000, 20 000 mg/kg. In order to better elucidate the biochemical and physiological responses to diesel pollutants, activity of the antioxidant enzymes peroxidase （POD）, catalase （CAT） and ascorbic acid oxidase （AAO） were determined in the plant tissue after 50 d treatment at the levels mentioned above. The results showed that CAT and AAO of stem and leaf exhibited peak enzyme activities on 15 000 mg/kg soil and 10 000 mg/kg soil respectively, and declined at higher concentrations. Additionally, the increment of biomass and the content of soluble protein, as well as chlorophyll content were affected by diesel. The highest restoration effectiveness appeared at the level of 5 000 mg/kg. Collectively, Cyperus rotundus is a potential plant which can be used for restoring the diesel-contaminated soil. 相似文献
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7.
采用离子液体/盐双水相萃取的方法,研究了亲水性离子液体[Bmim]BF4/盐双水相对氨苄西林钠萃取性能,分别讨论(NH4)2S04加入量、离子液体[Bmim]BF4体积及氨苄西林钠溶液浓度对萃取率的影响,并通过紫外分光光度计进一步验证了氨苄西林钠与离子液体的相互作用.结果表明,[BTnim]BF4/盐双水相萃取分离氨苄西林钠的最佳参数为:(NH4)2SO4质量0.55g,氨苄西林钠溶液浓度0.013mol·L-1,离子液体[Bmim]BF4体积2.5mL,氨苄西林钠溶液和离子液体[Bmim]BF4的体积比为1∶1. 相似文献
8.
Internal exposure of university students to polycyclic aromatic hydrocarbons(PAHs)was assessed through urinary PAHs metabolites. Eight monohydroxylated PAHs(OH-PAHs)were detected with high performance liquid chromatography (HPLC). The detectable frequencies were 59%-100% for different analytes. Major components in the subjects‘ urine were 2-hydroxynaphthalene(2-OHNap, 0.60 μg/mmol creatinine), followed by hydroxyphenanthrene(ΣOH-Phe, 0.38 μg/mmol cre-atinine)and 2-hydroxyfluorene(2-OHFlu, 0.25 μg/mmol creatinine). Excretion of 1-hydroxypyrene(1-OHPyr, 0.08 μg/mmol creatinine)was almost one order of magnitude lower than the 2-OHNap level in the urine samples. Phenanthrene can be metabolized to five monohydroxy metabolites in human urine. In the present study, 1-or 9-hydroxyphenanthrene(1-or9-OHPhe)was the dominant component(79%), followed by 2-+3-OHPhe(18%)and 4-OHPhe(3%). The study indicates that 1-OHPyr may not be a good marker for total PAHs exposure, and monitoring of 2-OHNap, 2-OHFlu, 1-or 9-OHPhe and 1-OHPyr as multiple biomarkers are more suitable than only using 1-OHPyr. The levels of OH-PAHs detected in urines of students living in Shanghai are higher those of people in other countries or regions. The concentrations of urine OH-PAHs are directly related to the exposure to PAHs in the environment, indicating that Shanghai residents are at high health risk. 相似文献
9.
采用溶胶-凝胶法,以硝酸铜、二氯化锡和钛酸四丁酯为原料,加入十六烷基三甲基溴化铵(CTAB)作软模板,制备CuO/SnO2/TiO2纳米复合物。分别用SEM、XRD、IR、UV-vis等对产物进行表征分析,CuO/SnO2/TiO2晶粒由锐钛矿相的TiO2、金红石相的SnO2和单斜晶系的CuO组成。以甲基橙为模拟污染物,研究其催化活性,结果表明CuO/SnO2/TiO2纳米复合物具有较好的光催化活性。 相似文献
10.
A series of polysulfonamide （PSA）/TiO 2 modifier nano-composite films were successfully prepared by in-situ polymerization at a low temperature based on 4, 4-diaminodiphenylsulfone and terephthaloyl chloride in the common solvent N, N-dimethylacetamide （DMAc）. It was shown that the nano particles were well dispersed in the polymer substrate. Mean-while, PSA/TiO 2 /modifier composites exhibited good UV-resistant properties and mechanical properties. In addition, the composites’ heat stability improved. These prepared composites are promising in preparing spinning solution and might have potential application in heat-resistant fiber. 相似文献
11.
采用溶胶-凝胶法制备了二氧化硅负载硅钨钼酸催化剂.以其为催化剂,对以丁酮和乙二醇为原料合成丁酮乙二醇缩酮的反应条件进行了研究,较系统地研究了酮醇物质的量比、催化剂用量、带水剂环己烷,反应时间对收率的影响.实验表明,二氧化硅负载硅钨钼酸催化剂是合成丁酮乙二醇缩酮的良好催化剂,在n（丁酮）∶n（乙二醇）=1∶1.4,催化剂用量为原料总质量的0.6%,环己烷作带水剂10 mL,反应时间75min的优化条件下,丁酮乙二醇缩酮的收率可达96.77%. 相似文献
12.
Nano-manipulation technology is an emerging field in the development of modern science and technology. Atomic force microscope （AFM）, a sharp weapon for nano imaging and nanomanipulation, which is honored as ＂eye＂ and ＂hand＂ of nano-technology. However, due to the hysteresis, creep and other nonlinearity of piezoelectric ceramics tube （PZT） as well as the probe＇s tip deviations caused by cantilever deformation, AFM has larger error of relative displacement between probe and sample, which creates enormous inconvenience to the nano-manipulation and repositioning. As to improve positioning accuracy, this dissertation presents a novel AFM＇s X-Y dimensional nano-positioning control system with large-scale based on H∞ control. Through careful research on variety of influence factors on AFM＇s precise nano-manipulation, a composite control strategy based on feedforward compensation control of cantilever probe tip＇s offset and H∞ control of piezoelectric scanner is presented in this paper. In the end, simulation results can also testify the tracking ability and better nano-positioning performance of the system. 相似文献
13.
It is difficult to study the mean value properties of the higher-Kloosterman sums S（m,n,q;k） for any positive integer k.In this paper,the fourth power mean of this exponential sums is studied by combining congruence theorey with the analytic method,and an interesting asymptotic formula for it is obtained.The new result is an important generalization and improvement of the previous. 相似文献
14.
A new customization approach based on support vector regression (SVR) is proposed to obtain individual headrelated
impulse response (HRIR) without complex measurement and special equipment. Principal component analysis (PCA) is
first applied to obtain a few principal components and corresponding weight vectors correlated with individual anthropometric
parameters. Then the weight vectors act as output of the nonlinear regression model. Some measured anthropometric
parameters are selected as input of the model according to the correlation coefficients between the parameters and the weight
vectors. After the regression model is learned from the training data, the individual HRIR can be predicted based on the
measured anthropometric parameters. Compared with a back-propagation neural network (BPNN) for nonlinear regression,
better generalization and prediction performance for small training samples can be obtained using the proposed PCA-SVR
algorithm. 相似文献
impulse response (HRIR) without complex measurement and special equipment. Principal component analysis (PCA) is
first applied to obtain a few principal components and corresponding weight vectors correlated with individual anthropometric
parameters. Then the weight vectors act as output of the nonlinear regression model. Some measured anthropometric
parameters are selected as input of the model according to the correlation coefficients between the parameters and the weight
vectors. After the regression model is learned from the training data, the individual HRIR can be predicted based on the
measured anthropometric parameters. Compared with a back-propagation neural network (BPNN) for nonlinear regression,
better generalization and prediction performance for small training samples can be obtained using the proposed PCA-SVR
algorithm. 相似文献
15.
焦更生 《渭南师范学院学报》2012,(2):57-60
为了提高C/C复合材料的高温抗氧化性能,设计了网状的SiC填充高性能的MoSi2和微量的TiSi2涂层,对制备涂层的化学形成机理进行了热力学分析.结果表明,在选择的实验条件下,制备设计的涂层是完全可行的,实验制备的涂层在1773K有氧环境下具有良好的抗氧化性能. 相似文献
16.
以二氧化硅负载磷钼钨酸H3PW6Mo6O40/SiO2为催化剂,苯甲醛和1,2-丙二醇为原料合成苯甲醛1,2-丙二醇缩醛.探讨H3PW6Mo6O40/SiO2对缩醛反应的催化活性,较系统地研究了醛醇物质的量比、催化剂用量、带水剂用量、反应时间等因素对产品收率的影响.实验表明:H3PW6Mo6O40/SiO2是合成苯甲醛1,2-丙二醇缩醛的良好催化剂,在n(苯甲醛)∶n(1,2丙二醇)=1∶1.5,催化剂用量为占总反应物质量的1.0%,带水剂环己烷用量10 mL,反应时间45 min的最佳条件下,苯甲醛1,2-丙二醇缩醛的收率可达83.3%. 相似文献
17.
This paper presents a rheology-based approach to animate realistic face model. The dynamic and biorheological
characteristics of the force member (muscles) and stressed member (face) are considered. The stressed face can be modeled
as viscoelastic bodies with the Hooke bodies and Newton bodies connected in a composite series-parallel manner. Then, the
stress-strain relationship is derived, and the constitutive equations established. Using these constitutive equations, the face
model can be animated with the force generated by muscles. Experimental results show that this method can realistically
simulate the mechanical properties and motion characteristics of human face, and performance of this method is satisfactory. 相似文献
characteristics of the force member (muscles) and stressed member (face) are considered. The stressed face can be modeled
as viscoelastic bodies with the Hooke bodies and Newton bodies connected in a composite series-parallel manner. Then, the
stress-strain relationship is derived, and the constitutive equations established. Using these constitutive equations, the face
model can be animated with the force generated by muscles. Experimental results show that this method can realistically
simulate the mechanical properties and motion characteristics of human face, and performance of this method is satisfactory. 相似文献
18.
Instead of manual polishing work for aluminum wheel hub （hub） surface, a new planetary scroll surface polishing method based on the rotation and revolution of hub in abrasives is presented in this paper. Since conventional barrel rotation polishing mode is unsatisfactory, shorter polishing period and lower energy consumption are expected. The surface polishing mechanism of the proposed method is ghen introduced. The influence of cutting velocity, cutting angle, abrasive on surface polishing quality and efficiency, as well as the correlation of the revolution velocity and the rotation velocity of hub are discussed. Experimental results show that high surface polishing quality and efficiency can be achieved with the new polishing method implying that a dustless clean working environment is realized. 相似文献
19.
以木屑为原料,高温热解制备生物炭。以聚乙烯醇为粘结剂,采用混合法将生物炭与果胶复合,并负载磁性,经烘干定型制备果胶包覆的磁性生物炭材料（果胶@生物炭-Fe3O4）。采用扫描电镜（SEM）、X射线衍射（XRD）及N2吸附-脱附（BET）等方法对果胶@生物炭-Fe3O4进行表征,结合吸附实验分析其对Cu2+的吸附特性。结果表明,当生物炭、果胶、Fe3O4质量比为5：1：1,溶液pH值为6,吸附24 h,果胶@生物炭-Fe3O4对Cu2+吸附效果最好;二级动力学方程能较好地描述果胶@生物炭-Fe3O4对Cu2+的吸附过程,Freundlich模型能较好地拟合其吸附行为;SEM结果显示该材料具有不规则的孔隙结构;XRD分析显示纳米Fe3O4是其主要的晶体结构;BET测得其比表面积为25.654 m2·g-1,平均孔径为20.18 nm。 相似文献
20.
Ba0.6Sr0.4TiO3 （BST） thin films with and without HfO 2 buffer layer were fabricated on Pt/Ti/SiO2/Si substrates by pulsed laser deposition. Dependences of HfO 2 thickness on the dielectric property and leakage current of BST thin films were focused. The dielectric constant of BST thin films increased and then decreased with the increase of HfO 2 thickness, while the dielectric relaxation was gradually improved. The loss tangent and leakage current under positive bias decreased with the HfO 2 thickness increasing. The leakage current analysis based on the Schottky emission indicated an improvement of the BST/Pt interface with HfO 2 buffer layer. The loss tangent, tunability and figure of merit of optimized HfO 2 buffered BST thin film achieved 0.009 8, 21.91% （E max = 200 kV/cm）, 22.40 at 10 6 Hz, respectively. 相似文献