Chinese Chang＇e lunar exploration project aims to collect and return subsurface lunar soil samples at a minimum penetration depth of 2 m in 2017. However, in contrast to those on the Earth, automated drilling and sam...Chinese Chang＇e lunar exploration project aims to collect and return subsurface lunar soil samples at a minimum penetration depth of 2 m in 2017. However, in contrast to those on the Earth, automated drilling and sampling missions on the Moon raise the risk of burning bits. Test-beds are required for testing the thermal properties of drill tools in a lunar environment. In this paper, a novel temperature measuring method based on thermocouples and a slip ring was proposed. Furthermore, a data acquisition system for a drilling process was designed. A vacuous, cryogenic, and anhydrous soil environment simulating the lunar surface was established. A drilling test-bed that can reach a depth of 2.2 m was developed. A control strategy based on online monitoring signals was proposed to improve the drilling performance. Vacuum and non-vacuum experiments were performed to test the temperature rising effect on drill tools. When compared with the non-vacuum experiment, the vacuum temperature rise resulted in a 12 ℃ increase. These experimental results provide significant support for Chinese lunar exploration missions.展开更多
Octaphenylsilsesquioxane(OPhS) was prepared by a modifying method and a new core-shell nanocomposite, octa(2,4-dinitrophenyl)silsesquioxane, [(R_2PhSiO_ 1.5)_8, R=—NO_2, ODNPhS], was synthesized by nitration of OPh...Octaphenylsilsesquioxane(OPhS) was prepared by a modifying method and a new core-shell nanocomposite, octa(2,4-dinitrophenyl)silsesquioxane, [(R_2PhSiO_ 1.5)_8, R=—NO_2, ODNPhS], was synthesized by nitration of OPhS in a mixed acid solution of nitric and sulfuric acids at about 60 ℃. Their molecular structures were determined by DRIFTS, 1H NMR, 13C NMR spectra analysis. The thermal analysis shows that ODNPhS is an explosive that detonates at about 420 ℃.展开更多
Utilizing N-[（4-carboxyphenyl）-sulfonyl]glycine （abbreviated as cbsglyH3）,a new cobalt complex [Co（cbsglyH）（bipy）2]3H2O （bipy = 2,2＇-bipyridine） has been synthesized under mild conditions and characterized ...Utilizing N-[（4-carboxyphenyl）-sulfonyl]glycine （abbreviated as cbsglyH3）,a new cobalt complex [Co（cbsglyH）（bipy）2]3H2O （bipy = 2,2＇-bipyridine） has been synthesized under mild conditions and characterized by IR,elemental analysis,thermogravimetric analysis and X-ray diffraction analysis. It crystallizes in the monoclinic system,space group C2/c with a = 34.978（3）,b = 12.0437（11）,c = 20.0041（19） ,β = 122.2990（10）°,V = 7123.0（11） 3,Z = 8,C29H28CoN5O9S,Mr = 681.55,μ = 0.593 mm-1,Dc = 1.271 Kg/m3,F（000） = 2816,the final R = 0.0434 and wR = 0.1351. The title complex is a monomeric compound which is further assembled by intermolecular hydrogen bonds into a 3-D supramolecular network. Thermogravimetric analysis illustrates that this complex begins decomposing at 100 ℃ and decompounding completely at 560 ℃.展开更多
One new coordination polymer with the chemical formula [CoCu2L2·K2·1.5C2H5OH]n（H4L = 2-hydroxy-3-[（E）-（{3-[（2-hydroxybenzoyl）amino]propyl}imino）methyl] benzoic acid） has been synthesized based on the...One new coordination polymer with the chemical formula [CoCu2L2·K2·1.5C2H5OH]n（H4L = 2-hydroxy-3-[（E）-（{3-[（2-hydroxybenzoyl）amino]propyl}imino）methyl] benzoic acid） has been synthesized based on the slow diffusion method,and characterized by IR spectroscopy,thermalgravimetric and X-ray diffraction analysis.It crystallizes in the monoclinic system,space group P21/n with a = 11.98860（10）,b = 24.4279（3）,c = 14.9008（2） ,β = 104.7490（10）°,V = 4220.01（8） 3,Z = 2,Mr = 1009.94,Dc = 1.590 g/cm3,F（000） = 2056,μ（MoKα） = 1.649 mm-1,the final R = 0.0411 and wR = 0.1178 for 5920 observed reflections with I 2σ（I）.The compound possesses a 2D brick wall structure constructed from trinuclear units.展开更多
The 808-nm vertical cavity surface emitting laser(VCSEL) with strained In_(0.13)Ga_(0.75)Al_(0.12)As/Al_(0.3)Ga_(0.7)As quantum wells is designed and fabricated. Compared with the VCSELs with Al_(0.05)Ga_(0.95)As/Al_(...The 808-nm vertical cavity surface emitting laser(VCSEL) with strained In_(0.13)Ga_(0.75)Al_(0.12)As/Al_(0.3)Ga_(0.7)As quantum wells is designed and fabricated. Compared with the VCSELs with Al_(0.05)Ga_(0.95)As/Al_(0.3)Ga_(0.7)As quantum wells, the VCSEL with strained In_(0.13)Ga_(0.75)Al_(0.12)As/Al_(0.3)Ga_(0.7)As quantum wells is demonstrated to possess higher power conversion efficiency(PCE) and better temperature stability. The maximum PCE of 43.8% for 10-μm VCSEL is achieved at an ambient temperature of 30°C. The size-dependent thermal characteristics are also analyzed by characterizing the spectral power and output power. It demonstrates that small oxide-aperture VCSELs are advantageous for temperature-stable performance.展开更多
The boroxine-linked organic aluminum compound LAl[OB（3-C4H3O）]2（μ-O） was accomplished by reacting LAl H2 {L =（Z）-4-[（2,6-diisopropylphenyl）amino]pent-3-en-2-ylidene-2,6-diisopropylaniline} with furan-3-ylboro...The boroxine-linked organic aluminum compound LAl[OB（3-C4H3O）]2（μ-O） was accomplished by reacting LAl H2 {L =（Z）-4-[（2,6-diisopropylphenyl）amino]pent-3-en-2-ylidene-2,6-diisopropylaniline} with furan-3-ylboronic acid in good yield.The title compound belongs to the orthorhombic system,space group Pnma with a = 10.9774（15）,b = 19.369（3）,c = 17.362（3） A,V = 3691.5（9） A^3,C37H47 Al B2N2O5,Mr = 648.37,Z = 4,Dc = 1.167 Mg/m^3,μ（Mo Kα） = 0.097 mm^–1,F（000） = 1384,S = 1.000,the final R = 0.0589 and w R = 0.1445 for 9138 observed reflections（I 〉 2σ（I）） and R = 0.0683 and w R = 0.1517 for all data.This compound is an unique example of a spiro-centered aluminum atom,showing the inorganic Al O3B2 ring fused to the organic C3N2 part.It was characterized by 1H NMR,IR,elemental analysis,and single-crystal X-ray structural analysis.Furthermore,the compound was studied by TG analysis as well as DSC.展开更多
The manganese(II) complex, [Mn(phen)2(4-CPOA)(H2O)]?5H2O (4-CPOAH2 = 4- carboxyphenoxyacetic acid) has been synthesized and characterized by elemental analyses, IR, TG and single-crystal X-ray diffraction. The cryst...The manganese(II) complex, [Mn(phen)2(4-CPOA)(H2O)]?5H2O (4-CPOAH2 = 4- carboxyphenoxyacetic acid) has been synthesized and characterized by elemental analyses, IR, TG and single-crystal X-ray diffraction. The crystal is of monoclinic, space group C2/c, with a = 27.471(3), b = 18.490(4), c = 14.507(3) ?, β = 115.13(3)o, V = 6671(3) ?3, Z = 8, Mr = 717.58, Dc= 1.429 g/cm3, μ = 0.462 mm–1, F(000) = 2984, the final R = 0.0535 and wR = 0.1200 for 5413 observed reflections with I > 2σ(I). The Mn(II) atom is coordinated by one O atom of 4-carboxy- phenoxyacetate, four N atoms of two 1,10-phenanthroline and one water molecule, residing in a distorted octahedral environment. A supramolecular network structure is formed by hydrogen bonds and π-π stacking interactions.展开更多
We investigate in this article the thermal coliductivity of array Of cylinders embedded in a homogeneous matrix. Using Green's function, we confirm that the method invented by Rayleigh can be generalized to deal w...We investigate in this article the thermal coliductivity of array Of cylinders embedded in a homogeneous matrix. Using Green's function, we confirm that the method invented by Rayleigh can be generalized to deal with thermal property of these systems. A technique for calculating effective thermal conductivities of these systems is proposed. As an example, we consider a system with square symmetry, and a neat formula for effective thermal conductivity is derived. We show that the method also includes the proof of Keller theorem.展开更多
Blends of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) and poly(butylene succinate-adipate) (PBSA), both biodegradable semicrystalline polyesters, were prepared with the ratio of PHBHHx/PBSA ranging from 80/...Blends of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) and poly(butylene succinate-adipate) (PBSA), both biodegradable semicrystalline polyesters, were prepared with the ratio of PHBHHx/PBSA ranging from 80/20 to 20/80 by melt mixing method. Differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), dynamic mechanical thermal analysis (DMA), polarizing optical microscopy (POM) and wide angle X-ray diffractometer (WAXD) were used to study the miscibility and crystallization behavior of PHBHHx/PBSA blends. Experimental results indicate that PHBHHx is immiscible with PBSA as shown by the almost unchanged glass transition temperature and the biphasic melt.展开更多
A series of Al3+-doped 3.5MgO·0.5MgF2·GeO2:Mn4+red-emitting phosphors is synthesized by high temperature solid-state reaction. The broad excitation band at 300 nm–380 nm, resulting from the4A2→4T1transitio...A series of Al3+-doped 3.5MgO·0.5MgF2·GeO2:Mn4+red-emitting phosphors is synthesized by high temperature solid-state reaction. The broad excitation band at 300 nm–380 nm, resulting from the4A2→4T1transition of Mn4+,exhibits a blue shift with the increase of Al2O3 content. The observation of the decreased Mn4+–O2-distance is explained by the crystal field theory. The temperature-dependent photoluminescence spectra with various amounts of Al2O3 content are comparatively measured and the calculation shows that the activation energy increases up to 0.41 eV at the Al2O3 content of 0.1 mol. The maximum phonon densities of state for these samples are calculated from Raman spectra and they are correlated with the thermal properties.展开更多
Magnesium alloys,the lightest structural metal,are used in the field of aeronautics and astronautics more and more,however they are still limited for the poor corrosion resistant and high temperature property.In order...Magnesium alloys,the lightest structural metal,are used in the field of aeronautics and astronautics more and more,however they are still limited for the poor corrosion resistant and high temperature property.In order to satisfy the need of long time store and short time operation at elevated temperature,coating with excellent corrosion resistance and thermal resistance was prepared on the surface of Mg alloy AZ31B.The cathodic electrophoretic deposition was applied for the preparation of coating.The bonding of organic electrophoretic deposition coating with substrate was improved using silane pretreatment.Nano-ZrO_(2) powder treated by silane was added into electrophoretic deposition solution.The corrosion resistance property of electrophoretic coating was evaluated using Machu test,and thermal characteristic using the thermal shock experiment and DTA respectively.The morphology of the coating was examined by SEM.It is found that both the corrosion resistant and thermal shock resistant properties can be improved by modifying the Mg specimen with APS silane,while adding nano-ZrO_(2)powder treated by GPS silane to the coating has the optimal effect.And the results also show that the main reason of the coating damage after thermal shock at 400°C or 500°C is mainly for the thermal stress.展开更多
The target compound(C18H14O4)was synthesized and structurally determined by single-crystal X-ray diffraction.The crystal is of monoclinic system,space group P21/n with a=7.9383(6),b=19.5083(13),c=9.4189(7)?,β=98.981(...The target compound(C18H14O4)was synthesized and structurally determined by single-crystal X-ray diffraction.The crystal is of monoclinic system,space group P21/n with a=7.9383(6),b=19.5083(13),c=9.4189(7)?,β=98.981(2)°,C18H14O4,Mr=294.29,Dc=1.357 g/cm^3,V=1440.75(18)?3,Z=4,F(000)=616,μ(MoKa)=0.096 mm-1,T=293(2)K,3320 independent reflections with 1845 observed ones(I>2σ(I)),R=0.0529 and wR=0.1082 with GOF=1.015(R=0.1202 and wR=0.1278 for all data).The phenanthrene skeleton is coplanar.The overall crystal packing revealed that it has reverse staggered parallel and stratified arrangement.And a one-dimensional interaction model was formed by two kinds ofπ-πinteractions between the two adjacent molecules at upper and lower levels.The decomposition mechanism of compound 3 is complex.展开更多
A novel ligand 11-oxa-4,5,9,10,12,13-hexaaza-cyclopenta [b] triphenylene （OHCT） and its coordination polymer [Zn（OHCT）（1,2-BDC）]n 1 （1,2-BDC = 1,2-benzenedicarboxylate） were synthesized and characterized. Crys...A novel ligand 11-oxa-4,5,9,10,12,13-hexaaza-cyclopenta [b] triphenylene （OHCT） and its coordination polymer [Zn（OHCT）（1,2-BDC）]n 1 （1,2-BDC = 1,2-benzenedicarboxylate） were synthesized and characterized. Crystallographic data for OHCT： C14H6N6O5, Mr = 274.25, monoclinic, space group P21/c, a = 10.755（3）, b = 11.710（4）, c = 9.516（3） , β = 108.457（4）o, V = 1136.9（6） 3, Dc = 1.602 g/cm3, μ（MoKα） = 0.111 mm-1, F（000） = 560, Z = 4, the final R = 0.1534 and wR = 0.39709. Crystallographic data for 1： C22H10ZnN6O5, Mr = 503.73, triclinic, space group P , a = 6.1411（5）, b = 10.9111（9）, c = 14.1925（1） , α = 89.1830（1）, β = 79.3030（1）, γ = 84.6350（1）o, V = 930.36（1） 3, Dc = 1.798 g/cm3, μ（MoKα） = 1.376 mm-1, F（000） = 508, Z = 2, the final R = 0.0323 and wR = 0.0789. 1 has been obtained by using hydrothermal synthesis and characterized by elemental analysis, IR spectrum, thermal analysis, fluorescence spectrum and single-crystal X-ray diffraction. In complex 1, the zinc atom is five-coordinated with three carboxylate oxygen atoms from three different 1,2-BDC ligands and two nitrogen atoms from one OHCT ligand, showing a distorted trigonal bipyramidal configuration.展开更多
The target compound(C19H20ClNO)was structurally determined by single-crystal X-ray diffraction.The crystal is in monoclinic system,space group P21/n with a=9.2365(2),b=12.1241(3),c=14.9960(4)?,β=106.589(3)°,C19H...The target compound(C19H20ClNO)was structurally determined by single-crystal X-ray diffraction.The crystal is in monoclinic system,space group P21/n with a=9.2365(2),b=12.1241(3),c=14.9960(4)?,β=106.589(3)°,C19H20ClNO,Mr=313.81,Dc=1.295 g/cm^3,V=1609.42(7)?3,Z=4,F(000)=664,μ(MoKa)=2.097 mm-1,T=200(10)K,2813 independent reflections with 2533 observed ones(I>2σ(I)),R=0.0389 and wR=0.1057 with GOF=1.043(R=0.0423 and wR=0.1083 for all data).The 3,4-dihydroquinolin-2(1 H)-one moiety maintains thermodynamically stable trans configuration.The decomposition mechanism of compound 3 is complex by thermal analysis.展开更多
By using a strong light-absorbing surface layer and front-surface illumination with a low power He-Ne laser ( 6mW), photoacoustic measurements of the thermal effusivities of materials have been made, based on the phot...By using a strong light-absorbing surface layer and front-surface illumination with a low power He-Ne laser ( 6mW), photoacoustic measurements of the thermal effusivities of materials have been made, based on the photoacoustic theory, derived in this paper, of condensed matter with a strong light- absorbing surface layer. This method can eliminate the stray light, give full play to the power of the light irradiation, and improve the signal to noise ratio. The experiment results are in good agreement with the theoretical values.展开更多
The thermotropic liquid crystal polyester(TLCP)fiber is an increasingly important strategic high-performance fiber.In this paper,the TLCP was prepared by two-step melt polymerization using 4-hydroxybenzoic acid(HBA)an...The thermotropic liquid crystal polyester(TLCP)fiber is an increasingly important strategic high-performance fiber.In this paper,the TLCP was prepared by two-step melt polymerization using 4-hydroxybenzoic acid(HBA)and 6-hydroxy-2-naphthoic acid(HNA)as comonomers at a molar ratio of 7∶3.The structure of TLCP was confirmed by the Fourier transform infrared(FTIR)spectrometer and nuclear magnetic resonance(NMR)spectrometer.The thermal and rheological properties of TLCP before and after heat treatment were analyzed systematically by the differential scanning calorimeter(DSC),dynamic mechanical analyzer(DMA)and high-temperature rotational rheometer.The results revealed that the melting temperature,glass transition temperature and melt viscosity of the TLCP increased significantly after heat treatment.It indicates that the crystallization of the TLCP is perfect,and solid-phase condensation occurs during heat treatment,which increases its molecular mass.In conclusion,heat treatment at a temperature below but close to the melting temperature can effectively regulate the structure and properties of the TLCP,and the results of this study can provide a reference for the high strengthening of TLCP fibers.展开更多
To prepare a high-performance epoxy resin with excellent thermal, chemical and corrosion stability, diaminoxanthone（DAX） was used to cure diglycidylether of bisphenol-A（DGEBA）-based epoxy resin and blend of DGEBA ...To prepare a high-performance epoxy resin with excellent thermal, chemical and corrosion stability, diaminoxanthone（DAX） was used to cure diglycidylether of bisphenol-A（DGEBA）-based epoxy resin and blend of DGEBA with functionalized Fe3O4 nanoparticles. Kinetic parameters of curing and thermal degradation of epoxy resin systems were estimated by differential scanning calorimetry（DSC） and thermogravimetric analysis（TGA）, respectively. The 10% weight loss temperature has been increased from 340 °C to 366 °C and there was an increase in the char yield from 32.6% to 45.3% for the above systems. The corrosion performance of epoxy coated carbon steel was examined by potentiodynamic polarization, along with immersion test in 1.0 mol/L HCl solution. The results showed that epoxy resins cured with DAX had low tendency to corrosion. In addition, the cured epoxy resin containing 10% Fe3O4 had higher anticorrosion activity than bare DGEBA system. The results showed that functionalized Fe3O4 nanoparticles enhanced char formation and improved the thermal stability as well as anticorrosion activity of the resin.展开更多
A novel material of ZrMnMo3012 with negative thermal expansion is presented. The phase transition temperature and coemcient of thermal expansion （CTE） are investigated by temperature-dependent x-ray diffraction and ...A novel material of ZrMnMo3012 with negative thermal expansion is presented. The phase transition temperature and coemcient of thermal expansion （CTE） are investigated by temperature-dependent x-ray diffraction and Raman spectra. It is shown that ZrMnMo3012 adopts monoclinic structure with space group P21/a （No. 14） from 298 to 358K and transforms to orthorhombic with space group Pnma （No. 62） above 363K. The linear CTE obtained from the results of XRD refinement is -2.80 × 10-6 K-1 from 363 to 873 K. The CTE of the bulk cylinder ceramic measured by a thermal dilatometer is -4.7× 10-6 K-1 from 373 to 773K approximatively.展开更多
The effect of rare earth elements on eutectic carbide′s morphology of low chromium semi steel in as cast state and after heat treatment was investigated, and accordingly, the thermal fatigue property of this mater...The effect of rare earth elements on eutectic carbide′s morphology of low chromium semi steel in as cast state and after heat treatment was investigated, and accordingly, the thermal fatigue property of this material was studied. The results show that RE can improve the eutectic carbide′s morphology, inhibit the formation and propagation of thermal fatigue cracks, therefore, promote the thermal fatigue property, which is more noticeable in case of the RE modification in combination with heat treatment. The optimal thermal fatigue property can be obtained when treated with 0.2% RE modification as well as normalization at 950 ℃ for 3 h.展开更多
The thermal fatigue property of Cr-W-Mo-Ni-Mn-RE ferric-base hardfacing layer was investigated. The results show that the generation and propagation of thermal fatigue cracks prefer the parts of oxidation and etching ...The thermal fatigue property of Cr-W-Mo-Ni-Mn-RE ferric-base hardfacing layer was investigated. The results show that the generation and propagation of thermal fatigue cracks prefer the parts of oxidation and etching of the grain boundary, the joint efforts of cycle stress and oxidation at high temperatures are the main factors in the generation and propagation of thermal fatigue cracks. When the temperatures is below 600 ℃, the Cr-W-Mo-Ni-Mn-RE ferric-base hardfacing layer has higher ability of thermal fatigue resistance. The function of the alloy and rare earth elements was discussed.展开更多
基金supported by the China Academy of Space Technology (CAST)
文摘Chinese Chang＇e lunar exploration project aims to collect and return subsurface lunar soil samples at a minimum penetration depth of 2 m in 2017. However, in contrast to those on the Earth, automated drilling and sampling missions on the Moon raise the risk of burning bits. Test-beds are required for testing the thermal properties of drill tools in a lunar environment. In this paper, a novel temperature measuring method based on thermocouples and a slip ring was proposed. Furthermore, a data acquisition system for a drilling process was designed. A vacuous, cryogenic, and anhydrous soil environment simulating the lunar surface was established. A drilling test-bed that can reach a depth of 2.2 m was developed. A control strategy based on online monitoring signals was proposed to improve the drilling performance. Vacuum and non-vacuum experiments were performed to test the temperature rising effect on drill tools. When compared with the non-vacuum experiment, the vacuum temperature rise resulted in a 12 ℃ increase. These experimental results provide significant support for Chinese lunar exploration missions.
文摘Octaphenylsilsesquioxane(OPhS) was prepared by a modifying method and a new core-shell nanocomposite, octa(2,4-dinitrophenyl)silsesquioxane, [(R_2PhSiO_ 1.5)_8, R=—NO_2, ODNPhS], was synthesized by nitration of OPhS in a mixed acid solution of nitric and sulfuric acids at about 60 ℃. Their molecular structures were determined by DRIFTS, 1H NMR, 13C NMR spectra analysis. The thermal analysis shows that ODNPhS is an explosive that detonates at about 420 ℃.
基金supported by the National Natural Science Foundation of China (Nos. 20771054 and 20471026)Henan Tackle Key Problem of Science and Technology (Nos. 072102270030 and 072102270034)
文摘Utilizing N-[（4-carboxyphenyl）-sulfonyl]glycine （abbreviated as cbsglyH3）,a new cobalt complex [Co（cbsglyH）（bipy）2]3H2O （bipy = 2,2＇-bipyridine） has been synthesized under mild conditions and characterized by IR,elemental analysis,thermogravimetric analysis and X-ray diffraction analysis. It crystallizes in the monoclinic system,space group C2/c with a = 34.978（3）,b = 12.0437（11）,c = 20.0041（19） ,β = 122.2990（10）°,V = 7123.0（11） 3,Z = 8,C29H28CoN5O9S,Mr = 681.55,μ = 0.593 mm-1,Dc = 1.271 Kg/m3,F（000） = 2816,the final R = 0.0434 and wR = 0.1351. The title complex is a monomeric compound which is further assembled by intermolecular hydrogen bonds into a 3-D supramolecular network. Thermogravimetric analysis illustrates that this complex begins decomposing at 100 ℃ and decompounding completely at 560 ℃.
基金Supported by the Technology Chamber of Henan Province (092300410031)the Education Chamber of Henan Province (2009A150005)
文摘One new coordination polymer with the chemical formula [CoCu2L2·K2·1.5C2H5OH]n（H4L = 2-hydroxy-3-[（E）-（{3-[（2-hydroxybenzoyl）amino]propyl}imino）methyl] benzoic acid） has been synthesized based on the slow diffusion method,and characterized by IR spectroscopy,thermalgravimetric and X-ray diffraction analysis.It crystallizes in the monoclinic system,space group P21/n with a = 11.98860（10）,b = 24.4279（3）,c = 14.9008（2） ,β = 104.7490（10）°,V = 4220.01（8） 3,Z = 2,Mr = 1009.94,Dc = 1.590 g/cm3,F（000） = 2056,μ（MoKα） = 1.649 mm-1,the final R = 0.0411 and wR = 0.1178 for 5920 observed reflections with I 2σ（I）.The compound possesses a 2D brick wall structure constructed from trinuclear units.
基金Project supported by the National Natural Science Foundation of China (Grant No. 61804175)the Key Research Program of Frontier Sciences, Chinese Academy of Sciences (Grant No. ZDBS-LY-JSC031)the China Postdoctoral Science Foundation (Grant No. BX20200358)。
文摘The 808-nm vertical cavity surface emitting laser(VCSEL) with strained In_(0.13)Ga_(0.75)Al_(0.12)As/Al_(0.3)Ga_(0.7)As quantum wells is designed and fabricated. Compared with the VCSELs with Al_(0.05)Ga_(0.95)As/Al_(0.3)Ga_(0.7)As quantum wells, the VCSEL with strained In_(0.13)Ga_(0.75)Al_(0.12)As/Al_(0.3)Ga_(0.7)As quantum wells is demonstrated to possess higher power conversion efficiency(PCE) and better temperature stability. The maximum PCE of 43.8% for 10-μm VCSEL is achieved at an ambient temperature of 30°C. The size-dependent thermal characteristics are also analyzed by characterizing the spectral power and output power. It demonstrates that small oxide-aperture VCSELs are advantageous for temperature-stable performance.
基金supported by the National Natural Science Foundation of China(No.21001016)the Beijing Natural Science Foundation(No.2132044)Beijing High School Youth Talent Project(YETP1191)
文摘The boroxine-linked organic aluminum compound LAl[OB（3-C4H3O）]2（μ-O） was accomplished by reacting LAl H2 {L =（Z）-4-[（2,6-diisopropylphenyl）amino]pent-3-en-2-ylidene-2,6-diisopropylaniline} with furan-3-ylboronic acid in good yield.The title compound belongs to the orthorhombic system,space group Pnma with a = 10.9774（15）,b = 19.369（3）,c = 17.362（3） A,V = 3691.5（9） A^3,C37H47 Al B2N2O5,Mr = 648.37,Z = 4,Dc = 1.167 Mg/m^3,μ（Mo Kα） = 0.097 mm^–1,F（000） = 1384,S = 1.000,the final R = 0.0589 and w R = 0.1445 for 9138 observed reflections（I 〉 2σ（I）） and R = 0.0683 and w R = 0.1517 for all data.This compound is an unique example of a spiro-centered aluminum atom,showing the inorganic Al O3B2 ring fused to the organic C3N2 part.It was characterized by 1H NMR,IR,elemental analysis,and single-crystal X-ray structural analysis.Furthermore,the compound was studied by TG analysis as well as DSC.
基金This work was supported by the National Natural Science Foundation of China (No. 20101003) Natural Science Foundationof Heilongjiang Province (No. B0007) and Outstanding Teacher Foundation of Heilongjiang Province (1054G036)
文摘The manganese(II) complex, [Mn(phen)2(4-CPOA)(H2O)]?5H2O (4-CPOAH2 = 4- carboxyphenoxyacetic acid) has been synthesized and characterized by elemental analyses, IR, TG and single-crystal X-ray diffraction. The crystal is of monoclinic, space group C2/c, with a = 27.471(3), b = 18.490(4), c = 14.507(3) ?, β = 115.13(3)o, V = 6671(3) ?3, Z = 8, Mr = 717.58, Dc= 1.429 g/cm3, μ = 0.462 mm–1, F(000) = 2984, the final R = 0.0535 and wR = 0.1200 for 5413 observed reflections with I > 2σ(I). The Mn(II) atom is coordinated by one O atom of 4-carboxy- phenoxyacetate, four N atoms of two 1,10-phenanthroline and one water molecule, residing in a distorted octahedral environment. A supramolecular network structure is formed by hydrogen bonds and π-π stacking interactions.
文摘We investigate in this article the thermal coliductivity of array Of cylinders embedded in a homogeneous matrix. Using Green's function, we confirm that the method invented by Rayleigh can be generalized to deal with thermal property of these systems. A technique for calculating effective thermal conductivities of these systems is proposed. As an example, we consider a system with square symmetry, and a neat formula for effective thermal conductivity is derived. We show that the method also includes the proof of Keller theorem.
基金The National Natural Science Foundation of China (No. 20374032) and Tianjin Science and Technology Key Project (No. 05YFSZSF02200)
文摘Blends of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) and poly(butylene succinate-adipate) (PBSA), both biodegradable semicrystalline polyesters, were prepared with the ratio of PHBHHx/PBSA ranging from 80/20 to 20/80 by melt mixing method. Differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), dynamic mechanical thermal analysis (DMA), polarizing optical microscopy (POM) and wide angle X-ray diffractometer (WAXD) were used to study the miscibility and crystallization behavior of PHBHHx/PBSA blends. Experimental results indicate that PHBHHx is immiscible with PBSA as shown by the almost unchanged glass transition temperature and the biphasic melt.
基金supported by the National High Technology Research and Development Program of China(Grant No.2013AA014201)the Natural Science Foundation of Tianjin City,China(Grant Nos.11JCYBJC00300 and 14JCZDJC31200)the National Key Foundation for Exploring Scientific Instrument of China(Grant No.2014YQ120351)
文摘A series of Al3+-doped 3.5MgO·0.5MgF2·GeO2:Mn4+red-emitting phosphors is synthesized by high temperature solid-state reaction. The broad excitation band at 300 nm–380 nm, resulting from the4A2→4T1transition of Mn4+,exhibits a blue shift with the increase of Al2O3 content. The observation of the decreased Mn4+–O2-distance is explained by the crystal field theory. The temperature-dependent photoluminescence spectra with various amounts of Al2O3 content are comparatively measured and the calculation shows that the activation energy increases up to 0.41 eV at the Al2O3 content of 0.1 mol. The maximum phonon densities of state for these samples are calculated from Raman spectra and they are correlated with the thermal properties.
文摘Magnesium alloys,the lightest structural metal,are used in the field of aeronautics and astronautics more and more,however they are still limited for the poor corrosion resistant and high temperature property.In order to satisfy the need of long time store and short time operation at elevated temperature,coating with excellent corrosion resistance and thermal resistance was prepared on the surface of Mg alloy AZ31B.The cathodic electrophoretic deposition was applied for the preparation of coating.The bonding of organic electrophoretic deposition coating with substrate was improved using silane pretreatment.Nano-ZrO_(2) powder treated by silane was added into electrophoretic deposition solution.The corrosion resistance property of electrophoretic coating was evaluated using Machu test,and thermal characteristic using the thermal shock experiment and DTA respectively.The morphology of the coating was examined by SEM.It is found that both the corrosion resistant and thermal shock resistant properties can be improved by modifying the Mg specimen with APS silane,while adding nano-ZrO_(2)powder treated by GPS silane to the coating has the optimal effect.And the results also show that the main reason of the coating damage after thermal shock at 400°C or 500°C is mainly for the thermal stress.
基金supported by the Natural Science Research Projects in Colleges and Universities of Anhui Province(No.KJ2019A0116)Natural Science Foundation of Anhui Province(No.1608085MB38)。
文摘The target compound(C18H14O4)was synthesized and structurally determined by single-crystal X-ray diffraction.The crystal is of monoclinic system,space group P21/n with a=7.9383(6),b=19.5083(13),c=9.4189(7)?,β=98.981(2)°,C18H14O4,Mr=294.29,Dc=1.357 g/cm^3,V=1440.75(18)?3,Z=4,F(000)=616,μ(MoKa)=0.096 mm-1,T=293(2)K,3320 independent reflections with 1845 observed ones(I>2σ(I)),R=0.0529 and wR=0.1082 with GOF=1.015(R=0.1202 and wR=0.1278 for all data).The phenanthrene skeleton is coplanar.The overall crystal packing revealed that it has reverse staggered parallel and stratified arrangement.And a one-dimensional interaction model was formed by two kinds ofπ-πinteractions between the two adjacent molecules at upper and lower levels.The decomposition mechanism of compound 3 is complex.
文摘A novel ligand 11-oxa-4,5,9,10,12,13-hexaaza-cyclopenta [b] triphenylene （OHCT） and its coordination polymer [Zn（OHCT）（1,2-BDC）]n 1 （1,2-BDC = 1,2-benzenedicarboxylate） were synthesized and characterized. Crystallographic data for OHCT： C14H6N6O5, Mr = 274.25, monoclinic, space group P21/c, a = 10.755（3）, b = 11.710（4）, c = 9.516（3） , β = 108.457（4）o, V = 1136.9（6） 3, Dc = 1.602 g/cm3, μ（MoKα） = 0.111 mm-1, F（000） = 560, Z = 4, the final R = 0.1534 and wR = 0.39709. Crystallographic data for 1： C22H10ZnN6O5, Mr = 503.73, triclinic, space group P , a = 6.1411（5）, b = 10.9111（9）, c = 14.1925（1） , α = 89.1830（1）, β = 79.3030（1）, γ = 84.6350（1）o, V = 930.36（1） 3, Dc = 1.798 g/cm3, μ（MoKα） = 1.376 mm-1, F（000） = 508, Z = 2, the final R = 0.0323 and wR = 0.0789. 1 has been obtained by using hydrothermal synthesis and characterized by elemental analysis, IR spectrum, thermal analysis, fluorescence spectrum and single-crystal X-ray diffraction. In complex 1, the zinc atom is five-coordinated with three carboxylate oxygen atoms from three different 1,2-BDC ligands and two nitrogen atoms from one OHCT ligand, showing a distorted trigonal bipyramidal configuration.
基金supported by the Natural Science Research Projects in Colleges and Universities of Anhui Province(No.KJ2019A0116)Natural Science Foundation of Anhui Province(No.1608085MB38)。
文摘The target compound(C19H20ClNO)was structurally determined by single-crystal X-ray diffraction.The crystal is in monoclinic system,space group P21/n with a=9.2365(2),b=12.1241(3),c=14.9960(4)?,β=106.589(3)°,C19H20ClNO,Mr=313.81,Dc=1.295 g/cm^3,V=1609.42(7)?3,Z=4,F(000)=664,μ(MoKa)=2.097 mm-1,T=200(10)K,2813 independent reflections with 2533 observed ones(I>2σ(I)),R=0.0389 and wR=0.1057 with GOF=1.043(R=0.0423 and wR=0.1083 for all data).The 3,4-dihydroquinolin-2(1 H)-one moiety maintains thermodynamically stable trans configuration.The decomposition mechanism of compound 3 is complex by thermal analysis.
文摘By using a strong light-absorbing surface layer and front-surface illumination with a low power He-Ne laser ( 6mW), photoacoustic measurements of the thermal effusivities of materials have been made, based on the photoacoustic theory, derived in this paper, of condensed matter with a strong light- absorbing surface layer. This method can eliminate the stray light, give full play to the power of the light irradiation, and improve the signal to noise ratio. The experiment results are in good agreement with the theoretical values.
基金National Key Research and Development Program of China (No.2021YFB3700105)。
文摘The thermotropic liquid crystal polyester(TLCP)fiber is an increasingly important strategic high-performance fiber.In this paper,the TLCP was prepared by two-step melt polymerization using 4-hydroxybenzoic acid(HBA)and 6-hydroxy-2-naphthoic acid(HNA)as comonomers at a molar ratio of 7∶3.The structure of TLCP was confirmed by the Fourier transform infrared(FTIR)spectrometer and nuclear magnetic resonance(NMR)spectrometer.The thermal and rheological properties of TLCP before and after heat treatment were analyzed systematically by the differential scanning calorimeter(DSC),dynamic mechanical analyzer(DMA)and high-temperature rotational rheometer.The results revealed that the melting temperature,glass transition temperature and melt viscosity of the TLCP increased significantly after heat treatment.It indicates that the crystallization of the TLCP is perfect,and solid-phase condensation occurs during heat treatment,which increases its molecular mass.In conclusion,heat treatment at a temperature below but close to the melting temperature can effectively regulate the structure and properties of the TLCP,and the results of this study can provide a reference for the high strengthening of TLCP fibers.
文摘To prepare a high-performance epoxy resin with excellent thermal, chemical and corrosion stability, diaminoxanthone（DAX） was used to cure diglycidylether of bisphenol-A（DGEBA）-based epoxy resin and blend of DGEBA with functionalized Fe3O4 nanoparticles. Kinetic parameters of curing and thermal degradation of epoxy resin systems were estimated by differential scanning calorimetry（DSC） and thermogravimetric analysis（TGA）, respectively. The 10% weight loss temperature has been increased from 340 °C to 366 °C and there was an increase in the char yield from 32.6% to 45.3% for the above systems. The corrosion performance of epoxy coated carbon steel was examined by potentiodynamic polarization, along with immersion test in 1.0 mol/L HCl solution. The results showed that epoxy resins cured with DAX had low tendency to corrosion. In addition, the cured epoxy resin containing 10% Fe3O4 had higher anticorrosion activity than bare DGEBA system. The results showed that functionalized Fe3O4 nanoparticles enhanced char formation and improved the thermal stability as well as anticorrosion activity of the resin.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11574276,51503185 and 51302249the Doctoral Fund of the Ministry of Education of China under Grant No 20114101110003
文摘A novel material of ZrMnMo3012 with negative thermal expansion is presented. The phase transition temperature and coemcient of thermal expansion （CTE） are investigated by temperature-dependent x-ray diffraction and Raman spectra. It is shown that ZrMnMo3012 adopts monoclinic structure with space group P21/a （No. 14） from 298 to 358K and transforms to orthorhombic with space group Pnma （No. 62） above 363K. The linear CTE obtained from the results of XRD refinement is -2.80 × 10-6 K-1 from 363 to 873 K. The CTE of the bulk cylinder ceramic measured by a thermal dilatometer is -4.7× 10-6 K-1 from 373 to 773K approximatively.
文摘The effect of rare earth elements on eutectic carbide′s morphology of low chromium semi steel in as cast state and after heat treatment was investigated, and accordingly, the thermal fatigue property of this material was studied. The results show that RE can improve the eutectic carbide′s morphology, inhibit the formation and propagation of thermal fatigue cracks, therefore, promote the thermal fatigue property, which is more noticeable in case of the RE modification in combination with heat treatment. The optimal thermal fatigue property can be obtained when treated with 0.2% RE modification as well as normalization at 950 ℃ for 3 h.
文摘The thermal fatigue property of Cr-W-Mo-Ni-Mn-RE ferric-base hardfacing layer was investigated. The results show that the generation and propagation of thermal fatigue cracks prefer the parts of oxidation and etching of the grain boundary, the joint efforts of cycle stress and oxidation at high temperatures are the main factors in the generation and propagation of thermal fatigue cracks. When the temperatures is below 600 ℃, the Cr-W-Mo-Ni-Mn-RE ferric-base hardfacing layer has higher ability of thermal fatigue resistance. The function of the alloy and rare earth elements was discussed.
