A field experiment was conducted from 1999 to 2002 to compare and evaluate the effects of nutrient and water regimes on paddy soil quality by investigating soil chemical and microbiological parameters. Four nutrient r...A field experiment was conducted from 1999 to 2002 to compare and evaluate the effects of nutrient and water regimes on paddy soil quality by investigating soil chemical and microbiological parameters. Four nutrient regimes, a control, chemical fertilizers only (CF), chemical fertilizers with swine manure (SM), and chemical fertilizers with wheat straw (WS), and two soil moisture regimes, continuous waterlogging (CWL) and alternate wetting and drying (AWD), were investigated. With SM and WS total organic carbon and total nitrogen in the paddy soil were significantly higher (P < 0.05) than those with CF. A similar effect for organic amendments was observed in the soil light fraction organic C (LFOC), water-soluble carbohydrates (WSC), and water-soluble organic C (WSOC). CWL, in particular when swine manure was incorporated into the paddy soil, markedly decreased soil redox potential (Eh) and increased total active reducing substances (ARS). Meanwhile, as compared to CF, SM and WS significantly (P < 0.05) increased soil microbial biomass C (MBC) and mineralizable carbon, with differences in AWD being higher than CWL. In addition, SM and WS treatments significantly (P < 0.05) improved rice above-ground biomass and grain yield, with AWD being greater than CWL. Thus, for ecologically sustainable agricultural management of paddy soils, long-term waterlogging should be avoided when organic manure was incorporated into paddy soil.展开更多
AIM: To probe into the genetic susceptibility of HLA-DRB1 alleles to esophageal carcinoma in Han Chinese in Hubei Province.METHODS: HLA-DRB1 allele polymorphisms were typed by polymerase chain reaction with sequence-s...AIM: To probe into the genetic susceptibility of HLA-DRB1 alleles to esophageal carcinoma in Han Chinese in Hubei Province.METHODS: HLA-DRB1 allele polymorphisms were typed by polymerase chain reaction with sequence-specific primers (PCR-SSP) in 42 unrelated patients with esophageal cancer and 136 unrelated normal control subjects and the associated HLA-DRB1 allele was measured by nucleotide sequence analysis with PCR.SAS software was used in statistics.RESULTS: Allele frequency (AF) of HLA-DRB1·0901 was significantly higher in esophageal carcinoma patients than that in the normal controls (0.2500 vs0.1397, P=0.028, the odds ratio 2.053, etiologic fraction 0.1282). After analyzed the allele nucleotide sequence of HLA-DRB1·0901 which approachs to the corresponded exon 2 sequence of the allele in genebank. There was no association between patients and controls in the rested HLA-DRB1 alleles.CONCLUSION: HLA-DRB1·0901 allele is more common in the patients with esophageal carcinoma than in the healthy controls, which is positively associated with the patients of Hubei Han Chinese. Individuals carrying HLA-DRB1·0901may be susceptible to esophageal carcinoma.展开更多
Friction stir welding achieves the weld in solid phase by locally introducing frictional heating and plastic flow arising from rotation of the welding tool, which results in changes in the local microstructure of magn...Friction stir welding achieves the weld in solid phase by locally introducing frictional heating and plastic flow arising from rotation of the welding tool, which results in changes in the local microstructure of magnesium alloy. The purpose in the paper is to study the microstructures of friction stir welded AZ31 magnesium alloy. Residual microstructures, including dynamic re-crystallization zone and nugget structures have been systematically investigated utilizing optical microscopy (OM), scanning electric microscopy (SEM), transmission electron microscopy (TEM) with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and micro-hardness. AZ31 magnesium alloy has been successfully friction stir welded and exhibits the variations of microstructure including dynamically recrystallized, equaxied grains in the weld nugget. Residual hardness in the nugget was found slightly lower than the parent but not too obvious.展开更多
Synthesis of the third-order nonlinear materials: bis (1,4-dihydroxynaphthalene) tetrathiafulvalene and bis (1,4-dialkoxylnaphthalene) tetrathiafulvalene has been achieved in four steps, starting from 2,3-dichloro-1,4...Synthesis of the third-order nonlinear materials: bis (1,4-dihydroxynaphthalene) tetrathiafulvalene and bis (1,4-dialkoxylnaphthalene) tetrathiafulvalene has been achieved in four steps, starting from 2,3-dichloro-1,4-naphthaquinone. The materials exhibit larger third-order nonlinear optical susceptibilities c(3) .展开更多
Surface modification of magnesium alloy AZ91HP (9wt%Al, 0.5wt%Zn, 0.5wt%Mn, Mg remaining percentage) by high current pulsed electron beam (HCPEB) treatment was studied in this paper. The secondary phase MgnAln is near...Surface modification of magnesium alloy AZ91HP (9wt%Al, 0.5wt%Zn, 0.5wt%Mn, Mg remaining percentage) by high current pulsed electron beam (HCPEB) treatment was studied in this paper. The secondary phase MgnAln is nearly completely dissolved and as a result, a super-saturated solid solution forms on the re-melted surface. The microhardness is increased both in and far beyond the heat-affected zone (HAZ), reaching about 250um. Measurements on sliding wear have shown that the wear resistance of the treated samples was improved by a factor of about 2.4 as compared to the as-received sample. It is also found that the sliding wear resistance can be further improved by surface alloying with TiN.展开更多
A novel scheme of M-ary multi-carrier spread spectrum based on wavelet packet is proposed. Its performance is investigated for a multipath, slow Rayleigh fading channel. The performance advantages of the system over t...A novel scheme of M-ary multi-carrier spread spectrum based on wavelet packet is proposed. Its performance is investigated for a multipath, slow Rayleigh fading channel. The performance advantages of the system over that based on DFT are demonstrated by both analytical and simulation methods.展开更多
An experimental way to analyze the thermal characterization of semiconductor lasers based on spectroscopy method under pulse driving conditions has been developed. By using this way the thermal characteristics of stra...An experimental way to analyze the thermal characterization of semiconductor lasers based on spectroscopy method under pulse driving conditions has been developed. By using this way the thermal characteristics of strain compensated 1.3 μm InAsP/InGaAsP ridge waveguide MQW laser diodes have been investigated. Results show that by measuring and analyzing the lasing spectra under appropriate driving parameters and temperature ranges, the thermal resistance of the laser diodes could be deduced easily. A higher thermal resistance of 640 K/W has been measured on a narrow ridge laser chip without soldering. Other thermal and spectral properties of the lasers have also been measured and discussed.展开更多
Reactive ion etching characteristics of GaAs,GaSb,InP and InAs using Cl2/Ar plasma have been investigated,it is that,etching rates and etching profiles as functions of etching time,gas flow ratio and RF power.Etch rat...Reactive ion etching characteristics of GaAs,GaSb,InP and InAs using Cl2/Ar plasma have been investigated,it is that,etching rates and etching profiles as functions of etching time,gas flow ratio and RF power.Etch rates of above 0.45 μm/min and 1.2 μm/min have been obtained in etching of GaAs and GaSb respectively, while very slow etch rates （<40 nm/min） were observed in etching of In-containing materials,which were linearly increased with the applied RF power.Etched surfaces have remained smooth over a wide range of plasma conditions in the etching of GaAs,InP and InAs,however,were partly blackened in etching of GaSb due to a rough appearance.展开更多
The novel free-form deformation (FFD) technique presented in the paper uses scalar fields definedby skeletons with arbitrary topology. The technique embeds objects into the scalar field by assigning a field value to e...The novel free-form deformation (FFD) technique presented in the paper uses scalar fields definedby skeletons with arbitrary topology. The technique embeds objects into the scalar field by assigning a field value to each point of the objects. When the space of the skeleton is changed, the distribution of the scalar field changes accordingly, which implicitly defines a deformation of the space. The generality of skeletons assures that the technique can freely define deformable regions to produce a broader range of shape deformations.展开更多
Mo is difficult to sinter densely at a relatively low temperature due to its high melting point. In the present paper, by adding different weight contents of Ni and Cu additives, Mo alloys have been densified at 1473 ...Mo is difficult to sinter densely at a relatively low temperature due to its high melting point. In the present paper, by adding different weight contents of Ni and Cu additives, Mo alloys have been densified at 1473 K for an hour by hot-pressing method, and the optimum contents of Cu and Ni additives have been acquired: when the contents of Ni and Cu are 3 and 2 wt pct respectively, the relative density of the sample reaches the maximum value. It was found that when the Ni-Cu solid solution was added into Mo alloys, the achieved density is higher than the case of Ni and Cu additives. The experimental results indicate that, Ni and Cu play different roles in the process of sintering, the Ni-Cu solid solution has the same function as Ni and Cu additives in the course of sintering Mo alloys, It shows more activating sintering feature for Mo than the Ni and Cu additives.展开更多
Software for calculating the strip profile in 4-high hot rolling mill was developed using influence coefficient method.Regularity of backup roller diameter effect rate was studied systematically using the software. Th...Software for calculating the strip profile in 4-high hot rolling mill was developed using influence coefficient method.Regularity of backup roller diameter effect rate was studied systematically using the software. The results show that backup roller diameter effect rates decrease versus the increase of strip width, increase significantly versus theincrease of backup roller diameter and obscurely increase versus the increase of reduction. The difference betweenbackup roller diameter effect rate and it is reference value increases versus strip width increasing. When backuprollers diameter is set to be 1.64 m and strip width is 1.85 m, the error of strip profile calculated using the model of backup roller diameter effect rate reference value will be 3.55 μm. Based on the results, reference values of roller diameter effect rate and six power polynomial fitting coefficients of modification coefficients were determined considering coherent parameters. The high precision model of backup roller diameter effect rate was established.When the model is used to predict strip profile, the accuracy is less than 5.0μm.展开更多
The hole transporting layer (HTL) of organic light-emitting device (OLED) was processed by vacuum deposition and spin coating method, respectively, where N,N’-biphenyl-N, N’-bis(3-methylphenyl)-1,1’-biphenyl-4,4’ ...The hole transporting layer (HTL) of organic light-emitting device (OLED) was processed by vacuum deposition and spin coating method, respectively, where N,N’-biphenyl-N, N’-bis(3-methylphenyl)-1,1’-biphenyl-4,4’ -diamine (TPD) and poly (vinylcarbazole) (PVK) acted as the hole-transport materials. Tris-(8-hydroxyquinoline)- aluminum (Alq3) was utilized as both the light-emitting layer and the electron transporting layer. The basic structure of the device cell was: indium-tin-oxide (ITO)/PVK : TPD/Alq3/Mg:Ag. The electroluminescent (EL) characteristics of devices were characterized. The results showed that the peak of EL spectra was located at 530 nm, which conformed to the characterizing spectrum of Alq3. Compared with using vacuum deposition method, the green emission with a maximum luminance up to 26135 cd/m2 could be achieved at a drive voltage of 15 V by selecting proper solvent using spin-coating technique, and its maximum lumi- nance efficiency was 2.56 lm/W at a drive voltage of 5.5 V.展开更多
Microcavity structure consisting of distributed Bragg reflector and metal aluminum mirror is designed. Using tris (8-hydroxyquinoline) aluminum as electron-transport layer and emissive layer, and N, N′-bis (3-methylp...Microcavity structure consisting of distributed Bragg reflector and metal aluminum mirror is designed. Using tris (8-hydroxyquinoline) aluminum as electron-transport layer and emissive layer, and N, N′-bis (3-methylphenyl)-N, N′-diphenylbenzidine as a hole-transport layer, microcavity organic light-emitting diodes(MOLEDs) are fabricated. Compared to the electroluminescence spectra of non-cavity OLEDs, the linewidth of the MOLEDs is compressed from 75 nm to 7 nm, and the peak intensity enhances by a factor of about 3. When the effective length of the microcavity is modified, resonance wavelength can be selectively scanned over a very wide range of wavelengths that cover almost 140 nm.展开更多
The application of irradiation in silicon crystal is introduced.The defects caused by irradiation are reviewed and some major ways of studying defects in irradiated silicon are summarized.Furthermore the problems in t...The application of irradiation in silicon crystal is introduced.The defects caused by irradiation are reviewed and some major ways of studying defects in irradiated silicon are summarized.Furthermore the problems in the investigation of irradiated silicon are discussed as well as its properties.展开更多
The AR coatings for GaInP/GaAs tandem solar cell are simulated.Results show that,under the condition of the lack of suitable encapsulation, a very low energy loss could be reached on MgF2/ZnS system; in the case of gl...The AR coatings for GaInP/GaAs tandem solar cell are simulated.Results show that,under the condition of the lack of suitable encapsulation, a very low energy loss could be reached on MgF2/ZnS system; in the case of glass encapsulation,the Al2O3/ZrO2 and Al2O3/TiO2 systems are appropriate choice; for AlInP window layer,the thickness of 30 nm is suitable.展开更多
A sedimentation method is proposed to fabricate functionally graded materials (FGMs) with the continuous andsmooth variations of composition. The relations between the compositional distribution of deposited body and ...A sedimentation method is proposed to fabricate functionally graded materials (FGMs) with the continuous andsmooth variations of composition. The relations between the compositional distribution of deposited body and thepowder characteristics of raw materials as well as settling parameters are derived. Subsequently, the mathematicalmodel of forming FGM based on the co-sedimentation has been established. At last, numerical simulations areconducted to explore the effects of the particle sizes of raw materials and suspension height on the compositionaldistribution of final products.展开更多
Based on the experiment and the thermodynamics analysis for CuO/Al system, it is founded that the compounding reaction of CuO/Al under low temperature is available. The general equation of adiabatic temperature of the...Based on the experiment and the thermodynamics analysis for CuO/Al system, it is founded that the compounding reaction of CuO/Al under low temperature is available. The general equation of adiabatic temperature of the system is set up, and the influence of resultant concentration and temperature on adiabatic temperature is theoretically analyzed. The values of heat effect of CuO/Al system under different temperature are also caculated.展开更多
Study on presolar grains including diamond, silicon carbide, graphite, silicon nitrite (Si\-3N\-4), corundum and spinel isolated from meteorites is summarized in this paper. Except for nanometer\|sized diamond, the ot...Study on presolar grains including diamond, silicon carbide, graphite, silicon nitrite (Si\-3N\-4), corundum and spinel isolated from meteorites is summarized in this paper. Except for nanometer\|sized diamond, the other grains are micrometers to submicrometers in size. The presolar grains survived mainly in the fine \|grained matrix of primitive chondrites and were isolated by chemical treatments. Diamond contains Xe isotopes (Xe\|HL), typically produced in p\| and r\|processes, probably formed in supernovae. Mainstream silicon carbides are enriched in \{\{\}\+\{29,30\}Si\} and \{\{\}\+\{13\}C\}, but depleted in \{\{\}\+\{15\}N\}. They also contain various s\|process products, consistent with calculations of AGB stars. Other silicon carbides exhibit much larger isotopic anomalies and are classified as groups X, Y, Z and AB. Among them, group X of SiC is characterized by enrichment of \{\{\}\+\{28\}Si\} and daughter isotopes of various short\|lived nuclides, suggesting an origin from supernovae. Graphite can be divided into four density fractions with distinct isotopic compositions. They may form in AGB stars, novae and supernovae, respectively. Si\-3N\-4 is similar to X\|SiC in isotopic composition. Corundum is classified as four groups based on their oxygen isotopic compositions. AGB and red giant stars are possible sources for the oxide. More comprehensive study of presolar grains, especially discovery of the other types of oxides and silicates, isotopic analyses of individual submicrometer\|sized grains and distribution of presolar grains among various chemical groups and petrographic types of chondrites will provide new information on nucleosynthesis, stellar evolution and formation of the solar nebula.展开更多
Amorphous carbon nitride thin films were prepared by plasma-enhanced DC magnetron sputtering using twinned microwave electron cyclotron resonance plasma sources. Chemical structure of deposited films was investigated ...Amorphous carbon nitride thin films were prepared by plasma-enhanced DC magnetron sputtering using twinned microwave electron cyclotron resonance plasma sources. Chemical structure of deposited films was investigated using X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The results indicate that the deposition rate is strongly affected by direct current bias, and the films are mainly composed of a single amorphous carbon nitride phase with N/C ratio close to C3N4, and the bonding is predominantly of C^N type.展开更多
Solder bridge is a serious defect of solder joints in ultrafine pitch electronic device assemblies. Generation of the solder bridge is closely related to forming process of the solder joints. A three-dimensional model...Solder bridge is a serious defect of solder joints in ultrafine pitch electronic device assemblies. Generation of the solder bridge is closely related to forming process of the solder joints. A three-dimensional model to simulate the formation of the solder bridge of QFP256 (quad flat packaging with 256 leads) is established and numerically calculated to predict the formation shape of the solder joints using surface evolver program. Based on the model, influence of structure of pads printed on circuit board on solder bridging is investigated. The results show that there is a critical solder volume Vc for solder joints to avoid solder bridging, and parameters of the pad size influence the critical solder volume.展开更多
基金1Project supported by the Knowledge Innovative Program of the Chinese Academy of Sciences (No. KZCX2-413) andthe National High Technology Research and Development Program of China (863 Program) (No. 2002AA601012).
文摘A field experiment was conducted from 1999 to 2002 to compare and evaluate the effects of nutrient and water regimes on paddy soil quality by investigating soil chemical and microbiological parameters. Four nutrient regimes, a control, chemical fertilizers only (CF), chemical fertilizers with swine manure (SM), and chemical fertilizers with wheat straw (WS), and two soil moisture regimes, continuous waterlogging (CWL) and alternate wetting and drying (AWD), were investigated. With SM and WS total organic carbon and total nitrogen in the paddy soil were significantly higher (P < 0.05) than those with CF. A similar effect for organic amendments was observed in the soil light fraction organic C (LFOC), water-soluble carbohydrates (WSC), and water-soluble organic C (WSOC). CWL, in particular when swine manure was incorporated into the paddy soil, markedly decreased soil redox potential (Eh) and increased total active reducing substances (ARS). Meanwhile, as compared to CF, SM and WS significantly (P < 0.05) increased soil microbial biomass C (MBC) and mineralizable carbon, with differences in AWD being higher than CWL. In addition, SM and WS treatments significantly (P < 0.05) improved rice above-ground biomass and grain yield, with AWD being greater than CWL. Thus, for ecologically sustainable agricultural management of paddy soils, long-term waterlogging should be avoided when organic manure was incorporated into paddy soil.
文摘AIM: To probe into the genetic susceptibility of HLA-DRB1 alleles to esophageal carcinoma in Han Chinese in Hubei Province.METHODS: HLA-DRB1 allele polymorphisms were typed by polymerase chain reaction with sequence-specific primers (PCR-SSP) in 42 unrelated patients with esophageal cancer and 136 unrelated normal control subjects and the associated HLA-DRB1 allele was measured by nucleotide sequence analysis with PCR.SAS software was used in statistics.RESULTS: Allele frequency (AF) of HLA-DRB1·0901 was significantly higher in esophageal carcinoma patients than that in the normal controls (0.2500 vs0.1397, P=0.028, the odds ratio 2.053, etiologic fraction 0.1282). After analyzed the allele nucleotide sequence of HLA-DRB1·0901 which approachs to the corresponded exon 2 sequence of the allele in genebank. There was no association between patients and controls in the rested HLA-DRB1 alleles.CONCLUSION: HLA-DRB1·0901 allele is more common in the patients with esophageal carcinoma than in the healthy controls, which is positively associated with the patients of Hubei Han Chinese. Individuals carrying HLA-DRB1·0901may be susceptible to esophageal carcinoma.
基金supported by the National High Technique Development Foundation of China(No.2002AA331160).
文摘Friction stir welding achieves the weld in solid phase by locally introducing frictional heating and plastic flow arising from rotation of the welding tool, which results in changes in the local microstructure of magnesium alloy. The purpose in the paper is to study the microstructures of friction stir welded AZ31 magnesium alloy. Residual microstructures, including dynamic re-crystallization zone and nugget structures have been systematically investigated utilizing optical microscopy (OM), scanning electric microscopy (SEM), transmission electron microscopy (TEM) with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and micro-hardness. AZ31 magnesium alloy has been successfully friction stir welded and exhibits the variations of microstructure including dynamically recrystallized, equaxied grains in the weld nugget. Residual hardness in the nugget was found slightly lower than the parent but not too obvious.
基金This research was supported by the National Natural Science Foundation (29476227) the Natural Science Foundation of Zhejiang Province (1999-299003).
文摘Synthesis of the third-order nonlinear materials: bis (1,4-dihydroxynaphthalene) tetrathiafulvalene and bis (1,4-dialkoxylnaphthalene) tetrathiafulvalene has been achieved in four steps, starting from 2,3-dichloro-1,4-naphthaquinone. The materials exhibit larger third-order nonlinear optical susceptibilities c(3) .
文摘Surface modification of magnesium alloy AZ91HP (9wt%Al, 0.5wt%Zn, 0.5wt%Mn, Mg remaining percentage) by high current pulsed electron beam (HCPEB) treatment was studied in this paper. The secondary phase MgnAln is nearly completely dissolved and as a result, a super-saturated solid solution forms on the re-melted surface. The microhardness is increased both in and far beyond the heat-affected zone (HAZ), reaching about 250um. Measurements on sliding wear have shown that the wear resistance of the treated samples was improved by a factor of about 2.4 as compared to the as-received sample. It is also found that the sliding wear resistance can be further improved by surface alloying with TiN.
基金Supported by the National Natural Science Foundation of China(No.60172029)
文摘A novel scheme of M-ary multi-carrier spread spectrum based on wavelet packet is proposed. Its performance is investigated for a multipath, slow Rayleigh fading channel. The performance advantages of the system over that based on DFT are demonstrated by both analytical and simulation methods.
文摘An experimental way to analyze the thermal characterization of semiconductor lasers based on spectroscopy method under pulse driving conditions has been developed. By using this way the thermal characteristics of strain compensated 1.3 μm InAsP/InGaAsP ridge waveguide MQW laser diodes have been investigated. Results show that by measuring and analyzing the lasing spectra under appropriate driving parameters and temperature ranges, the thermal resistance of the laser diodes could be deduced easily. A higher thermal resistance of 640 K/W has been measured on a narrow ridge laser chip without soldering. Other thermal and spectral properties of the lasers have also been measured and discussed.
文摘Reactive ion etching characteristics of GaAs,GaSb,InP and InAs using Cl2/Ar plasma have been investigated,it is that,etching rates and etching profiles as functions of etching time,gas flow ratio and RF power.Etch rates of above 0.45 μm/min and 1.2 μm/min have been obtained in etching of GaAs and GaSb respectively, while very slow etch rates （<40 nm/min） were observed in etching of In-containing materials,which were linearly increased with the applied RF power.Etched surfaces have remained smooth over a wide range of plasma conditions in the etching of GaAs,InP and InAs,however,were partly blackened in etching of GaSb due to a rough appearance.
文摘The novel free-form deformation (FFD) technique presented in the paper uses scalar fields definedby skeletons with arbitrary topology. The technique embeds objects into the scalar field by assigning a field value to each point of the objects. When the space of the skeleton is changed, the distribution of the scalar field changes accordingly, which implicitly defines a deformation of the space. The generality of skeletons assures that the technique can freely define deformable regions to produce a broader range of shape deformations.
基金This research is sponsored by the National Natural Science Foundation of China under grant No.50171049.
文摘Mo is difficult to sinter densely at a relatively low temperature due to its high melting point. In the present paper, by adding different weight contents of Ni and Cu additives, Mo alloys have been densified at 1473 K for an hour by hot-pressing method, and the optimum contents of Cu and Ni additives have been acquired: when the contents of Ni and Cu are 3 and 2 wt pct respectively, the relative density of the sample reaches the maximum value. It was found that when the Ni-Cu solid solution was added into Mo alloys, the achieved density is higher than the case of Ni and Cu additives. The experimental results indicate that, Ni and Cu play different roles in the process of sintering, the Ni-Cu solid solution has the same function as Ni and Cu additives in the course of sintering Mo alloys, It shows more activating sintering feature for Mo than the Ni and Cu additives.
基金the National Natu-ral Science Foundation of China,under the contract No.59995440the State Key Development Prograrmming Research under the contract No.G2000027208-4 the Natural Science Foundation ofLiaoning Province,under the contract No.2001101021.
文摘Software for calculating the strip profile in 4-high hot rolling mill was developed using influence coefficient method.Regularity of backup roller diameter effect rate was studied systematically using the software. The results show that backup roller diameter effect rates decrease versus the increase of strip width, increase significantly versus theincrease of backup roller diameter and obscurely increase versus the increase of reduction. The difference betweenbackup roller diameter effect rate and it is reference value increases versus strip width increasing. When backuprollers diameter is set to be 1.64 m and strip width is 1.85 m, the error of strip profile calculated using the model of backup roller diameter effect rate reference value will be 3.55 μm. Based on the results, reference values of roller diameter effect rate and six power polynomial fitting coefficients of modification coefficients were determined considering coherent parameters. The high precision model of backup roller diameter effect rate was established.When the model is used to predict strip profile, the accuracy is less than 5.0μm.
基金This project was sponsored by Ministry level fundingthe Young Excellence Project of UESTC.(Grant No.: UESTC-2006206)
文摘The hole transporting layer (HTL) of organic light-emitting device (OLED) was processed by vacuum deposition and spin coating method, respectively, where N,N’-biphenyl-N, N’-bis(3-methylphenyl)-1,1’-biphenyl-4,4’ -diamine (TPD) and poly (vinylcarbazole) (PVK) acted as the hole-transport materials. Tris-(8-hydroxyquinoline)- aluminum (Alq3) was utilized as both the light-emitting layer and the electron transporting layer. The basic structure of the device cell was: indium-tin-oxide (ITO)/PVK : TPD/Alq3/Mg:Ag. The electroluminescent (EL) characteristics of devices were characterized. The results showed that the peak of EL spectra was located at 530 nm, which conformed to the characterizing spectrum of Alq3. Compared with using vacuum deposition method, the green emission with a maximum luminance up to 26135 cd/m2 could be achieved at a drive voltage of 15 V by selecting proper solvent using spin-coating technique, and its maximum lumi- nance efficiency was 2.56 lm/W at a drive voltage of 5.5 V.
文摘Microcavity structure consisting of distributed Bragg reflector and metal aluminum mirror is designed. Using tris (8-hydroxyquinoline) aluminum as electron-transport layer and emissive layer, and N, N′-bis (3-methylphenyl)-N, N′-diphenylbenzidine as a hole-transport layer, microcavity organic light-emitting diodes(MOLEDs) are fabricated. Compared to the electroluminescence spectra of non-cavity OLEDs, the linewidth of the MOLEDs is compressed from 75 nm to 7 nm, and the peak intensity enhances by a factor of about 3. When the effective length of the microcavity is modified, resonance wavelength can be selectively scanned over a very wide range of wavelengths that cover almost 140 nm.
文摘The application of irradiation in silicon crystal is introduced.The defects caused by irradiation are reviewed and some major ways of studying defects in irradiated silicon are summarized.Furthermore the problems in the investigation of irradiated silicon are discussed as well as its properties.
文摘The AR coatings for GaInP/GaAs tandem solar cell are simulated.Results show that,under the condition of the lack of suitable encapsulation, a very low energy loss could be reached on MgF2/ZnS system; in the case of glass encapsulation,the Al2O3/ZrO2 and Al2O3/TiO2 systems are appropriate choice; for AlInP window layer,the thickness of 30 nm is suitable.
基金This research is sponsored by the National Natural Science Foundation of China under grant No,50171049the Doctoral Science Foundation of Ministty of Education of China under the grant 1999049702.
文摘A sedimentation method is proposed to fabricate functionally graded materials (FGMs) with the continuous andsmooth variations of composition. The relations between the compositional distribution of deposited body and thepowder characteristics of raw materials as well as settling parameters are derived. Subsequently, the mathematicalmodel of forming FGM based on the co-sedimentation has been established. At last, numerical simulations areconducted to explore the effects of the particle sizes of raw materials and suspension height on the compositionaldistribution of final products.
文摘Based on the experiment and the thermodynamics analysis for CuO/Al system, it is founded that the compounding reaction of CuO/Al under low temperature is available. The general equation of adiabatic temperature of the system is set up, and the influence of resultant concentration and temperature on adiabatic temperature is theoretically analyzed. The values of heat effect of CuO/Al system under different temperature are also caculated.
文摘Study on presolar grains including diamond, silicon carbide, graphite, silicon nitrite (Si\-3N\-4), corundum and spinel isolated from meteorites is summarized in this paper. Except for nanometer\|sized diamond, the other grains are micrometers to submicrometers in size. The presolar grains survived mainly in the fine \|grained matrix of primitive chondrites and were isolated by chemical treatments. Diamond contains Xe isotopes (Xe\|HL), typically produced in p\| and r\|processes, probably formed in supernovae. Mainstream silicon carbides are enriched in \{\{\}\+\{29,30\}Si\} and \{\{\}\+\{13\}C\}, but depleted in \{\{\}\+\{15\}N\}. They also contain various s\|process products, consistent with calculations of AGB stars. Other silicon carbides exhibit much larger isotopic anomalies and are classified as groups X, Y, Z and AB. Among them, group X of SiC is characterized by enrichment of \{\{\}\+\{28\}Si\} and daughter isotopes of various short\|lived nuclides, suggesting an origin from supernovae. Graphite can be divided into four density fractions with distinct isotopic compositions. They may form in AGB stars, novae and supernovae, respectively. Si\-3N\-4 is similar to X\|SiC in isotopic composition. Corundum is classified as four groups based on their oxygen isotopic compositions. AGB and red giant stars are possible sources for the oxide. More comprehensive study of presolar grains, especially discovery of the other types of oxides and silicates, isotopic analyses of individual submicrometer\|sized grains and distribution of presolar grains among various chemical groups and petrographic types of chondrites will provide new information on nucleosynthesis, stellar evolution and formation of the solar nebula.
基金supported by the National Natural Science Foundation of China under grant number 50135040&90206022.
文摘Amorphous carbon nitride thin films were prepared by plasma-enhanced DC magnetron sputtering using twinned microwave electron cyclotron resonance plasma sources. Chemical structure of deposited films was investigated using X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The results indicate that the deposition rate is strongly affected by direct current bias, and the films are mainly composed of a single amorphous carbon nitride phase with N/C ratio close to C3N4, and the bonding is predominantly of C^N type.
文摘Solder bridge is a serious defect of solder joints in ultrafine pitch electronic device assemblies. Generation of the solder bridge is closely related to forming process of the solder joints. A three-dimensional model to simulate the formation of the solder bridge of QFP256 (quad flat packaging with 256 leads) is established and numerically calculated to predict the formation shape of the solder joints using surface evolver program. Based on the model, influence of structure of pads printed on circuit board on solder bridging is investigated. The results show that there is a critical solder volume Vc for solder joints to avoid solder bridging, and parameters of the pad size influence the critical solder volume.
