The synthesis of dispersions of MMA (methylmethacrylate) with different concentrations of oleic acid coated nano-TiO_2 particles was performed by hydrolysis of TiCI_4 in the mixture solutions of MMA, oleic acid and H_...The synthesis of dispersions of MMA (methylmethacrylate) with different concentrations of oleic acid coated nano-TiO_2 particles was performed by hydrolysis of TiCI_4 in the mixture solutions of MMA, oleic acid and H_2O with various concentrations. When MMA: oleic acid: H_2O : TiCi_4 =1.00: 0.064 : 0.01: 0.032 (by mol fraction), the dispersion of MMA with oleic acid coated nano-TiO_2 particles was very stable. Optical absorption result showed that the absorption band was located in the ultraviolet range from 200 to 400 nm. This dispersion was added to a kind of automobile surface lustering agent (type II), and then this lustering agent with nano-TiO_2 was coated on the surface of automobile surface paint. When the doping amount of the dispersion in the lustering agent=10 vol. pct, the state of paint (color and glossiness) did not present any change after irradiation of an ultraviolet lamp with the power of 1000 watt for two days. The sample with surface paint and lustering agent doped by 10 percent dispersion after suffering from irradiation of the sunlight for half a year (from May to November) kept the original state. However, for the samples with automobile paint and lustering agent without doping of nano- TiO_2, the color and glossiness lost easily after irradiation of an ultraviolet lamp. These results prove that nano-TiO_2 is a kind of high-efficient additive of paint for protection against ultraviolet irradiation.展开更多
The influence of three important operation parameters in Jinlong flashsmelting furnace, including the distributing blast speed, the oxygen enrichment rate of process airand the ratio of central oxygen to overall oxyge...The influence of three important operation parameters in Jinlong flashsmelting furnace, including the distributing blast speed, the oxygen enrichment rate of process airand the ratio of central oxygen to overall oxygen (O_c/O_o), has been investigated using a virtualsimulation system on copper flash smelting furnace. The core of this virtual simulation system is anumerical simulation of CFD (computational fluid dynamics), and this system incorporates couplingmomentum transport, heat transport, mass transport, reaction kinetics between gas and particles andchemical reactions between gas and gas. A set of numerical predicted data were obtained. The CFDsimulation shows that there is a sensitive zone of the distributing blast speed, and the dustcontent ascends when the speed exceeds 180 m centre dot s^(-1). Increasing the oxygen concentrationof processing air benefits the efficient production of the flash smelting furnace.展开更多
Fluid flow, heat transfer and combustion in Jinlong CJD concentrate burnerflash smelting furnace have been investigated by numerical modeling and flow visualization. Themodeling is based on the Eulerian approach for t...Fluid flow, heat transfer and combustion in Jinlong CJD concentrate burnerflash smelting furnace have been investigated by numerical modeling and flow visualization. Themodeling is based on the Eulerian approach for the gas flow equations and the Lagrangian approachfor the particles. Interaction between the gas phase and particle phase, such as frictional forces,heat and mass transfer, are included by the addition of sources and sinks. The modeling resultsincluding the fluid flow field, temperature field, concentration field of gas phase and thetrajectories of particles have been obtained. The predicted results are in good agreement with thedata obtained from a series of experiments and tests in the Jinlong Copper Smelter and thetemperature error is less than 20 K.展开更多
Du’an Yao Autonomous County is a typical area for the distribution of karst rocky desertification in Guangxi. The indices for the grades of rocky desertification are selected according to the scientific meaning of ka...Du’an Yao Autonomous County is a typical area for the distribution of karst rocky desertification in Guangxi. The indices for the grades of rocky desertification are selected according to the scientific meaning of karst rocky desertification and after the interpretative symbol system of rocky desertification. RS images are established by the landscape characteristics of Du’an karst and its TM image. Relying on RS & GIS means and taking land use map as base map, this paper conducts synthetic analysis on the 1999a TM image (126-043) and the correlation data involving landform, soil, geological map and GPS—database and photo on the spot, and brings forth a map showing the Du’an rocky desertification grades and a digital lithology map. As can be viewed from spatial correlation, the inherent connection is also illuminated between the various levels of rocky desertification and the carbonate lithology.展开更多
The change of the temperature coefficient of resistivity (a) with the particle size, dp, and the grain size, dc, in the nanostructured Ag bulk samples was investigated. dp and dc were controlled by heating the nano-Ag...The change of the temperature coefficient of resistivity (a) with the particle size, dp, and the grain size, dc, in the nanostructured Ag bulk samples was investigated. dp and dc were controlled by heating the nano-Ag powders over the temperature range from 393 to 453 K. The electrical resistance measurements of the nanostructured Ag bulk samples obtained by compacting the Ag powders after heat treatments showed a change in the sign of a with dP and dc. When dp and dc are smaller or equal to 18 and 11 nm below room temperature or 20 and 12 nm above room temperature, respectively, the sign of the temperature coefficient of resistivity changes from positive to negative. The negative a arises mainly from the high resistivity induced by the particle interfaces with very lowly ordered or even disordered structure, a large volume fraction of interfaces and impurities existing in the interfaces, and the quantum size effect appearing in the nano-Ag grains.展开更多
The relationship between the stress intensity factor K_1~* required for brittle crack initiation and propa- gation and the fractal dimension D_F of the fracture surface was derived,i.e, InK_1~*=(1/2)In2γE'+(1/2)I...The relationship between the stress intensity factor K_1~* required for brittle crack initiation and propa- gation and the fractal dimension D_F of the fracture surface was derived,i.e, InK_1~*=(1/2)In2γE'+(1/2)In(d_f/L_0)(1-D_F) The real surface energy can be calculated based on the measured linear relation of the InK_1~* vs D_F, The equation is not only suitable for the overload fracture but also for the delayed fracture,e.g. hydrogen induced cracking (HIC) and stress corrosion cracking (SCC).The experiment results showed that the hydrogen induced delayed cracking occurred in the Ti-24AI-11 Nb alloy during dy- namic charging,and the threshold stress intensity factor was very low,i.e..K_(IH)/K_(IC)= 0.43.The ex- perimental relationship between the stress intensity factor K_1~* and D_F was consistent with the theo- retical equation.展开更多
In situ tensile test of brass foil specimens in TEM showed that many dislocations were emitted from a loaded crack tip, and a dislocation free zone (DFZ) was formed under the condition of constant displacement. The D...In situ tensile test of brass foil specimens in TEM showed that many dislocations were emitted from a loaded crack tip, and a dislocation free zone (DFZ) was formed under the condition of constant displacement. The DFZ is an elastic zone, where the stress may equal to the cohesive strength sigma //t//h when the applied stress is high enough. As a result, nano-cracks would initiate discontinuously in the DFZ or, sometimes, at a blunted-crack tip. As soon as the nano-crack nucleated, it quickly blunts into a void, which results in ductile fracture. (Edited author abstract) 10 Refs.展开更多
Alumina aerogels with high porosity of nanometer size were prepared from Al, n-butanol and ethyl acetoacetate by the sol-gel route and the N2 supercritical extraction drying technique. Optical experiment results showe...Alumina aerogels with high porosity of nanometer size were prepared from Al, n-butanol and ethyl acetoacetate by the sol-gel route and the N2 supercritical extraction drying technique. Optical experiment results showed that for alumina aerogels after annealing at 500℃ for 4 h one intense blue emission band appeared in the wavelength range of 400 to 800 nm, and the optical absorption edge moved from 8.0 eV of coarse grain Al203 to 3～eV and with increasing the annealing temperature, this luminescence band presented blue shifts. The reasons of these new optical properties are discussed in detail.展开更多
Effect of solution treatment temperature on transformations and two way memory, effect in a Ti- 55.2 wt-%Ni alloy was investigated. The results show that with increasing the solution treatment temperature (T_s), two w...Effect of solution treatment temperature on transformations and two way memory, effect in a Ti- 55.2 wt-%Ni alloy was investigated. The results show that with increasing the solution treatment temperature (T_s), two way memory effect (TWME) decreases continuously and temperatures of martensite and reverse, martensite transformations (MR) rise, but the temperature of R start trans- formation (parent→R) does not change. The results of the internal friction measurements indicate that when T_s=1073 K, internal friction peaks of MR and P→R transformations are larger than those of the specimens after solution-treatments at 973 and 1173 K. With increasing T_s, the de- crease of TWME can be attributed to that the defect stress field caused by the rolling fades out grad- ually and preferential martensite variants, which fit into the defect stress field, decrease. The changes of transformation temperatures and internal friction peaks with T_s are closely related to the change of defect numbers.展开更多
文摘The synthesis of dispersions of MMA (methylmethacrylate) with different concentrations of oleic acid coated nano-TiO_2 particles was performed by hydrolysis of TiCI_4 in the mixture solutions of MMA, oleic acid and H_2O with various concentrations. When MMA: oleic acid: H_2O : TiCi_4 =1.00: 0.064 : 0.01: 0.032 (by mol fraction), the dispersion of MMA with oleic acid coated nano-TiO_2 particles was very stable. Optical absorption result showed that the absorption band was located in the ultraviolet range from 200 to 400 nm. This dispersion was added to a kind of automobile surface lustering agent (type II), and then this lustering agent with nano-TiO_2 was coated on the surface of automobile surface paint. When the doping amount of the dispersion in the lustering agent=10 vol. pct, the state of paint (color and glossiness) did not present any change after irradiation of an ultraviolet lamp with the power of 1000 watt for two days. The sample with surface paint and lustering agent doped by 10 percent dispersion after suffering from irradiation of the sunlight for half a year (from May to November) kept the original state. However, for the samples with automobile paint and lustering agent without doping of nano- TiO_2, the color and glossiness lost easily after irradiation of an ultraviolet lamp. These results prove that nano-TiO_2 is a kind of high-efficient additive of paint for protection against ultraviolet irradiation.
文摘The influence of three important operation parameters in Jinlong flashsmelting furnace, including the distributing blast speed, the oxygen enrichment rate of process airand the ratio of central oxygen to overall oxygen (O_c/O_o), has been investigated using a virtualsimulation system on copper flash smelting furnace. The core of this virtual simulation system is anumerical simulation of CFD (computational fluid dynamics), and this system incorporates couplingmomentum transport, heat transport, mass transport, reaction kinetics between gas and particles andchemical reactions between gas and gas. A set of numerical predicted data were obtained. The CFDsimulation shows that there is a sensitive zone of the distributing blast speed, and the dustcontent ascends when the speed exceeds 180 m centre dot s^(-1). Increasing the oxygen concentrationof processing air benefits the efficient production of the flash smelting furnace.
文摘Fluid flow, heat transfer and combustion in Jinlong CJD concentrate burnerflash smelting furnace have been investigated by numerical modeling and flow visualization. Themodeling is based on the Eulerian approach for the gas flow equations and the Lagrangian approachfor the particles. Interaction between the gas phase and particle phase, such as frictional forces,heat and mass transfer, are included by the addition of sources and sinks. The modeling resultsincluding the fluid flow field, temperature field, concentration field of gas phase and thetrajectories of particles have been obtained. The predicted results are in good agreement with thedata obtained from a series of experiments and tests in the Jinlong Copper Smelter and thetemperature error is less than 20 K.
基金supported jointly by National Natural Science Foundation of China(Grant Nos.40161004 and 40361002)Guangxi Natural Science Foundation(Guikeji Grant No.0236046 and Guikezi Grant No.0342001-2)the Resource and Environmental Information System Laboratory project of Guangxi Teachers Education University-Guangxi Science and Technological Innovation Unit.
文摘Du’an Yao Autonomous County is a typical area for the distribution of karst rocky desertification in Guangxi. The indices for the grades of rocky desertification are selected according to the scientific meaning of karst rocky desertification and after the interpretative symbol system of rocky desertification. RS images are established by the landscape characteristics of Du’an karst and its TM image. Relying on RS & GIS means and taking land use map as base map, this paper conducts synthetic analysis on the 1999a TM image (126-043) and the correlation data involving landform, soil, geological map and GPS—database and photo on the spot, and brings forth a map showing the Du’an rocky desertification grades and a digital lithology map. As can be viewed from spatial correlation, the inherent connection is also illuminated between the various levels of rocky desertification and the carbonate lithology.
基金the National Natural Science FOundation of China under grant! No.19974041the National Major Fundamental ResearCh Program-Nal
文摘The change of the temperature coefficient of resistivity (a) with the particle size, dp, and the grain size, dc, in the nanostructured Ag bulk samples was investigated. dp and dc were controlled by heating the nano-Ag powders over the temperature range from 393 to 453 K. The electrical resistance measurements of the nanostructured Ag bulk samples obtained by compacting the Ag powders after heat treatments showed a change in the sign of a with dP and dc. When dp and dc are smaller or equal to 18 and 11 nm below room temperature or 20 and 12 nm above room temperature, respectively, the sign of the temperature coefficient of resistivity changes from positive to negative. The negative a arises mainly from the high resistivity induced by the particle interfaces with very lowly ordered or even disordered structure, a large volume fraction of interfaces and impurities existing in the interfaces, and the quantum size effect appearing in the nano-Ag grains.
文摘The relationship between the stress intensity factor K_1~* required for brittle crack initiation and propa- gation and the fractal dimension D_F of the fracture surface was derived,i.e, InK_1~*=(1/2)In2γE'+(1/2)In(d_f/L_0)(1-D_F) The real surface energy can be calculated based on the measured linear relation of the InK_1~* vs D_F, The equation is not only suitable for the overload fracture but also for the delayed fracture,e.g. hydrogen induced cracking (HIC) and stress corrosion cracking (SCC).The experiment results showed that the hydrogen induced delayed cracking occurred in the Ti-24AI-11 Nb alloy during dy- namic charging,and the threshold stress intensity factor was very low,i.e..K_(IH)/K_(IC)= 0.43.The ex- perimental relationship between the stress intensity factor K_1~* and D_F was consistent with the theo- retical equation.
文摘In situ tensile test of brass foil specimens in TEM showed that many dislocations were emitted from a loaded crack tip, and a dislocation free zone (DFZ) was formed under the condition of constant displacement. The DFZ is an elastic zone, where the stress may equal to the cohesive strength sigma //t//h when the applied stress is high enough. As a result, nano-cracks would initiate discontinuously in the DFZ or, sometimes, at a blunted-crack tip. As soon as the nano-crack nucleated, it quickly blunts into a void, which results in ductile fracture. (Edited author abstract) 10 Refs.
文摘Alumina aerogels with high porosity of nanometer size were prepared from Al, n-butanol and ethyl acetoacetate by the sol-gel route and the N2 supercritical extraction drying technique. Optical experiment results showed that for alumina aerogels after annealing at 500℃ for 4 h one intense blue emission band appeared in the wavelength range of 400 to 800 nm, and the optical absorption edge moved from 8.0 eV of coarse grain Al203 to 3～eV and with increasing the annealing temperature, this luminescence band presented blue shifts. The reasons of these new optical properties are discussed in detail.
文摘Effect of solution treatment temperature on transformations and two way memory, effect in a Ti- 55.2 wt-%Ni alloy was investigated. The results show that with increasing the solution treatment temperature (T_s), two way memory effect (TWME) decreases continuously and temperatures of martensite and reverse, martensite transformations (MR) rise, but the temperature of R start trans- formation (parent→R) does not change. The results of the internal friction measurements indicate that when T_s=1073 K, internal friction peaks of MR and P→R transformations are larger than those of the specimens after solution-treatments at 973 and 1173 K. With increasing T_s, the de- crease of TWME can be attributed to that the defect stress field caused by the rolling fades out grad- ually and preferential martensite variants, which fit into the defect stress field, decrease. The changes of transformation temperatures and internal friction peaks with T_s are closely related to the change of defect numbers.
文摘目的 调查川东北地区某医学院校大学生精神健康素养的现状及影响因素,为高等院校有针对性地开展医学生精神卫生教育提供依据。方法 采用单纯随机抽样的方法,于2022年6月在川东北地区某医学院校抽取在校大学生1 000人进行精神卫生与心理保健知识问卷(mental health and mental health knowledge questionnaire,MHMHKQ)、精神疾病有关态度问卷(devaluation-discrimination scale,DDS)调查,并对数据进行分析。结果 在校大学生MHMHKQ平均得分为(15.61±2.68)分,合格率为93.4%;DDS平均得分为(36.07±5.43)分,合格率为61.2%。不同性别、年级、生源地、是否接受过精神卫生相关知识教育、是否学习过《精神病学》的MHMHKQ得分比较,差异均有统计学意义(均P<0.05);不同年级的DDS得分比较,差异有统计学意义(P<0.05);不同性别、年级、是否学习过《精神病学》的MHMHKQ合格率比较,差异均有统计学意义(均P<0.05);不同年级和是否学习过《精神病学》的DDS合格率比较,差异均有统计学意义(均P<0.05)。多元线性回归分析结果显示,性别、年级、是否接受过精神卫生相关知识教育、是否学习过《精神病学》均是影响MHMHKQ得分的独立危险因素。多因素logistic回归分析结果显示,低年级和学习过《精神病学》的学生对待精神疾病患者的态度较好。结论 川东北地区某医学院校大学生具备较高的精神健康素养,精神卫生与心理保健知识掌握情况总体较好,尤其是女性、低年级、城镇生源、接受过精神卫生相关知识教育的学生,但对精神疾病的态度仍有待提高。学校应加强非医学专业学生的精神健康教育,传播精神卫生相关知识,以达到提高精神健康素养的目的。
