A dimeric chromium compound has been synthesized by hydrothermal method and characterized by IR, EPR spectra and TG-DTA technique. The title compound [Cr（aea）]2（OH）2 （aea = N-（2-aminoethyl）aspartate） crystalli...A dimeric chromium compound has been synthesized by hydrothermal method and characterized by IR, EPR spectra and TG-DTA technique. The title compound [Cr（aea）]2（OH）2 （aea = N-（2-aminoethyl）aspartate） crystallizes in monoclinic, space group P21/c with a = 8.9393（10）, b = 6.7198（7）, c = 14.6791（16） A, β = 91.0580（10）°, V= 881.63（17） A3, Z= 2, Mr = 486.34, De= 1.832 g/cm3, F（000） = 500,μ = 1.296 mm-1, R = 0.0271 and wR = 0.0756. Single-crystal X-ray structural analysis indicates that the title compound consists of two Cr（aea） units linked by two bridging hydroxyl groups. The geometry around each chromium center is approximately octahedral and completed by two hydroxyls and a quadridentate ligand which is formed when ethylenediamine reacts with maleic acid.展开更多
Spray-drying was used to produce the high emissivity NiCr2O4 powders with a spinel structure. Preliminary investigations focused on fabricating the high emissivity powders for infrared radiation coatings and finding t...Spray-drying was used to produce the high emissivity NiCr2O4 powders with a spinel structure. Preliminary investigations focused on fabricating the high emissivity powders for infrared radiation coatings and finding the relationship between microstructure and emissivity. The NiCr2O4 powders were characterized for composition, microstructure, and infrared emissivity by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, infrared radiant instrument, and Fourier transform infrared spectra （FT-IR）. Thermogravimetry and differential thermal analysis show that the appropriate baking temperature for NiCr2O4 powder preparation is about 1200？C. The emissivity measurement and FT-IR spectra show that, because of the special spinel structure, the NiCr2O4 powders have a high emissivity about 0.91. Spray-drying is a suitable method to produce the high emissivity ceramic powders.展开更多
A novel method to extract protein and Cr(III) from the chrome leather scrap discarded by leather industry is described. Chrome leather scarp was hydrolyzed under basic condition to remove chromium compound and extract...A novel method to extract protein and Cr(III) from the chrome leather scrap discarded by leather industry is described. Chrome leather scarp was hydrolyzed under basic condition to remove chromium compound and extract protein. The extracted protein was mixed with substrate and used as feed protein after being dried and ground. The basic residue was treated with sulfuric acid to obtain chrome(III) sulfate which can be used as tanning agent again after adjusting pH with base. The acidic residue was processed and used as flower fertilizer. The safety of the protein powder produced has been by toxicology and nutriology test. This reclamation method has been industrialized.展开更多
One of characteristics of Cr2O3-containing refractory is excellent corrosion resistance. However, there is a problem of hexavalent chromium, which is noxious to the human body, and easily formed by the reactions among...One of characteristics of Cr2O3-containing refractory is excellent corrosion resistance. However, there is a problem of hexavalent chromium, which is noxious to the human body, and easily formed by the reactions among the refractory and CaO, Na2O and/or K2O in slag. In this article, the reason why the Cr2O3-containing refractory has excellent corrosion resistance, the forming conditions of hexavalent compounds, and the methods for suppressing generation of the compound, are described as a base of further development of excellent refractories.展开更多
The preparation of divalent chromium N-heterocyclic carbene（NHC,1,3-diisopropyl4,5-dimethylimidazole-2-ylidene） compounds is reported.The reaction of 1：1 molar ratio of NHC with CrCl2 led to an isolation of [（NHC...The preparation of divalent chromium N-heterocyclic carbene（NHC,1,3-diisopropyl4,5-dimethylimidazole-2-ylidene） compounds is reported.The reaction of 1：1 molar ratio of NHC with CrCl2 led to an isolation of [（NHC）CrCl（μ-Cl）（THF）]2（1）,while that of 2：1 ratio resulted in the formation of（NHC）2CrCl2（2）.1 can be considered as an intermediate in the formation of 2 and further converted into 2 by the addition of another equiv.of NHC.The reaction of 2 with CpNa afforded an ion pair compound [（NHC）2CrCp]＋[Cp]-（3）,indicating a strong coordination ability of NHC supplanting one of the ionic Cr-Cp bonding.In combination of methylalumoxane（MAO） as cocatalyst 1 and 2 both are active for catalyzing ethylene polymerization.展开更多
The nonlinear optical properties of a new organic material, N-vinylcarbazole tricarbonyl chromium, are reported. The large two-photon absorption （TPA） coefficient and nonlinear refraction index are measured by an op...The nonlinear optical properties of a new organic material, N-vinylcarbazole tricarbonyl chromium, are reported. The large two-photon absorption （TPA） coefficient and nonlinear refraction index are measured by an open-aperture Z-scan technique and closed-aperture Z-scan technique, respectively. The sample solution shows excellent optical limiting response.展开更多
A pre-pumped passively Q-switched Nd:YAG/Cr: YAG microchip laser is demonstrated with a peak power of 7.5 kW at pulse repetition rate of serveral kilohertzs. The full-width at half-maximum (FWHM) is 734 ps, and the pu...A pre-pumped passively Q-switched Nd:YAG/Cr: YAG microchip laser is demonstrated with a peak power of 7.5 kW at pulse repetition rate of serveral kilohertzs. The full-width at half-maximum (FWHM) is 734 ps, and the pulse energy is 5.5 μJ with a fundamental spatial mode. In this system, the pre-pumped microchip laser of Nd: YAG/Cr: YAG wafer which is bonded through the thermal-bonding technique has achieved a time jitter value of 12 μs and a Q-switched amplitude instability of 1.26% (1δ) through the pre-pumped modulation technique.展开更多
基金Supported by the Ministry of Education of China (No. 207068)the Natural Science Foundation of Henan Province (No. 0611023000)Henan University (06YBZR017)
文摘A dimeric chromium compound has been synthesized by hydrothermal method and characterized by IR, EPR spectra and TG-DTA technique. The title compound [Cr（aea）]2（OH）2 （aea = N-（2-aminoethyl）aspartate） crystallizes in monoclinic, space group P21/c with a = 8.9393（10）, b = 6.7198（7）, c = 14.6791（16） A, β = 91.0580（10）°, V= 881.63（17） A3, Z= 2, Mr = 486.34, De= 1.832 g/cm3, F（000） = 500,μ = 1.296 mm-1, R = 0.0271 and wR = 0.0756. Single-crystal X-ray structural analysis indicates that the title compound consists of two Cr（aea） units linked by two bridging hydroxyl groups. The geometry around each chromium center is approximately octahedral and completed by two hydroxyls and a quadridentate ligand which is formed when ethylenediamine reacts with maleic acid.
文摘Spray-drying was used to produce the high emissivity NiCr2O4 powders with a spinel structure. Preliminary investigations focused on fabricating the high emissivity powders for infrared radiation coatings and finding the relationship between microstructure and emissivity. The NiCr2O4 powders were characterized for composition, microstructure, and infrared emissivity by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, infrared radiant instrument, and Fourier transform infrared spectra （FT-IR）. Thermogravimetry and differential thermal analysis show that the appropriate baking temperature for NiCr2O4 powder preparation is about 1200？C. The emissivity measurement and FT-IR spectra show that, because of the special spinel structure, the NiCr2O4 powders have a high emissivity about 0.91. Spray-drying is a suitable method to produce the high emissivity ceramic powders.
文摘A novel method to extract protein and Cr(III) from the chrome leather scrap discarded by leather industry is described. Chrome leather scarp was hydrolyzed under basic condition to remove chromium compound and extract protein. The extracted protein was mixed with substrate and used as feed protein after being dried and ground. The basic residue was treated with sulfuric acid to obtain chrome(III) sulfate which can be used as tanning agent again after adjusting pH with base. The acidic residue was processed and used as flower fertilizer. The safety of the protein powder produced has been by toxicology and nutriology test. This reclamation method has been industrialized.
文摘One of characteristics of Cr2O3-containing refractory is excellent corrosion resistance. However, there is a problem of hexavalent chromium, which is noxious to the human body, and easily formed by the reactions among the refractory and CaO, Na2O and/or K2O in slag. In this article, the reason why the Cr2O3-containing refractory has excellent corrosion resistance, the forming conditions of hexavalent compounds, and the methods for suppressing generation of the compound, are described as a base of further development of excellent refractories.
基金supported by the National Natural Science Foundation of China (20842006)the Research Fund for New Teacher of Higher Education+1 种基金the Initiation Research Fund for Returned Overseas Researchersthe 985 Project of Chinese Education Ministry
文摘The preparation of divalent chromium N-heterocyclic carbene（NHC,1,3-diisopropyl4,5-dimethylimidazole-2-ylidene） compounds is reported.The reaction of 1：1 molar ratio of NHC with CrCl2 led to an isolation of [（NHC）CrCl（μ-Cl）（THF）]2（1）,while that of 2：1 ratio resulted in the formation of（NHC）2CrCl2（2）.1 can be considered as an intermediate in the formation of 2 and further converted into 2 by the addition of another equiv.of NHC.The reaction of 2 with CpNa afforded an ion pair compound [（NHC）2CrCp]＋[Cp]-（3）,indicating a strong coordination ability of NHC supplanting one of the ionic Cr-Cp bonding.In combination of methylalumoxane（MAO） as cocatalyst 1 and 2 both are active for catalyzing ethylene polymerization.
基金This research was supported by the National Natural Science Foundation of China (Nos. 10234030 and 10574046) National Key Project for Basic Research of China (No. 1999075204) Program for New Century Excellent Talents in University (No. NCET-04-0420) Optics Project sponsored by Shanghai Science and Technology Committee (No. 036105019) Twilight Project sponsored by Shanghai Education Committee (No. 03SG23).
文摘The nonlinear optical properties of a new organic material, N-vinylcarbazole tricarbonyl chromium, are reported. The large two-photon absorption （TPA） coefficient and nonlinear refraction index are measured by an open-aperture Z-scan technique and closed-aperture Z-scan technique, respectively. The sample solution shows excellent optical limiting response.
文摘A pre-pumped passively Q-switched Nd:YAG/Cr: YAG microchip laser is demonstrated with a peak power of 7.5 kW at pulse repetition rate of serveral kilohertzs. The full-width at half-maximum (FWHM) is 734 ps, and the pulse energy is 5.5 μJ with a fundamental spatial mode. In this system, the pre-pumped microchip laser of Nd: YAG/Cr: YAG wafer which is bonded through the thermal-bonding technique has achieved a time jitter value of 12 μs and a Q-switched amplitude instability of 1.26% (1δ) through the pre-pumped modulation technique.
