Open-celled porous NiAl intermetallics with adjustable pore characteristics and mechanical properties were successfully prepared by using spherical carbamide as space-holders via combustion synthesis.Examinations of m...Open-celled porous NiAl intermetallics with adjustable pore characteristics and mechanical properties were successfully prepared by using spherical carbamide as space-holders via combustion synthesis.Examinations of macroscopic and microscopic morphologies as well as the quasi-static compressive test for the resultant materials were carried out.Depending on the volume fraction and particle size of the carbamide,the porosity and pore size of the porous NiAl intermetallics can be controlled freely in a range of 57.57%-84.58% and 0.4-2.0 mm,respectively.Furthermore,quasi-static compressive tests indicate that the mechanical behavior of the present porous materials is in good agreement with the Gibson-Ashby model.展开更多
Chemical doping is an effective method to intrinsically modify the chemical and electronic property of graphene. We propose a novel approach to synthesize the nitrogen-doped graphene via thermal annealing graphene wit...Chemical doping is an effective method to intrinsically modify the chemical and electronic property of graphene. We propose a novel approach to synthesize the nitrogen-doped graphene via thermal annealing graphene with urea, in which the nitrogen source can be controllably released from the urea by varying the annealed temperature and time. The doped N content and the configuration N as well as the thermal stabilities are also evaluated with X-ray photoelectron spectroscopy and Raman spectra. Electrical measurements indi- cate that the conductivity of doped graphene can be well regulated with the N content. The method is expected to produce large scale and controllable N-doped graphene sheets for a variety of potential applications.展开更多
A novel bead form of ploymer of high sorption capacity for urea were obtained by the reaction of glutaric dialdehyde wigh chitosan dispersed in acetic acid solution. The sorption capacity reached ￣ 82.0 mg / g sorbe...A novel bead form of ploymer of high sorption capacity for urea were obtained by the reaction of glutaric dialdehyde wigh chitosan dispersed in acetic acid solution. The sorption capacity reached ￣ 82.0 mg / g sorbent at 37℃ and pH 7.4 The concentration of urea in the buffer solution was 1300 mg/ L. The sorption of urea was related to the degree of crosslinking of the sorbent, concentration ofurea, ionic strength and temperature.展开更多
Toluene-2,4-bisurea (TBU) is an important intermediate for urea route to dimethyl toluene-2,4-dicarbamate and the study on TBU synthesis via the reaction of 2,4-toluene diamine (TDA) and urea is of great significance....Toluene-2,4-bisurea (TBU) is an important intermediate for urea route to dimethyl toluene-2,4-dicarbamate and the study on TBU synthesis via the reaction of 2,4-toluene diamine (TDA) and urea is of great significance. Firstly, thermodynamic analysis shows that the reaction is exothermic and a high equilibrium conversion of TDA is expected due to its large reaction equilibrium constant. Secondly, under the suitable reaction conditions, 130 °C, 7 h, and molar ratio of TDA/zinc acetate/urea/sulfolane 1/0.05/3.5/10, TDA conversion is 54.3%, and TBU yield and selectivity are 39.8% and 73.3% respectively. Lastly, the synthesis of TBU is a 1st order reaction with respect to TDA and the reaction kinetics model is established. This work will provide useful information for commercializing the urea route to toluene-2,4-dicarbamate (TDC).展开更多
A series of Zn–Ca–Al oxides with different CaO and ZnO contents have been prepared and evaluated in the synthesis of propylene carbonate(PC) from 1,2-propylene glycol(PG) and urea in a batch reactor. The effect of c...A series of Zn–Ca–Al oxides with different CaO and ZnO contents have been prepared and evaluated in the synthesis of propylene carbonate(PC) from 1,2-propylene glycol(PG) and urea in a batch reactor. The effect of catalyst composition, basicity and reaction process parameters such as temperature, catalyst dose, molar ratio of PG to urea, purge gas flow and reaction time has been studied to find suitable reaction conditions for the PC synthesis. The PC selectivity and yield under the desired conditions could reach 98.4% and 90.8%, respectively. The best performing catalyst also exhibited a good reusability without appreciable loss in the PC selectivity and yield after five consecutive reaction runs. In addition, a stepwise reaction pathway involving a 2-hydroxypropyl carbamate intermediate was proposed for the urea alcoholysis to PC in the presence of Zn–Ca–Al catalysts, according to the time dependences of reaction intermediates and products.展开更多
The crystal structure of [Ni(C5H2N2O4)(2, 2?bipy)(H2O)2]?H2O 1 has been determined by X-ray diffraction. Crystal data: triclinic system, space group P with a = 7.9424(3), b = 9.9417(3), c = 12.1867(3) ? a = 84.771(1),...The crystal structure of [Ni(C5H2N2O4)(2, 2?bipy)(H2O)2]?H2O 1 has been determined by X-ray diffraction. Crystal data: triclinic system, space group P with a = 7.9424(3), b = 9.9417(3), c = 12.1867(3) ? a = 84.771(1), b = 77.375(2), g = 68.993(2)? C15H18N4O8Ni, Mr = 440.7, V = 876.16(5) 3, Z = 2, Dc = 1.672 g/cm3, F(000) = 456, m(MoKa) = 1.162 mm-1, the final R = 0.0464 and wR = 0.1055 for 3026 observed reflections with I > 2s(I). In the title compound, the nickel ion is coordinated by a nitrogen atom and an oxygen atom from the orotate ligand, two nitrogen atoms from 2, 2?bipy and two oxygen atoms from the coordinated water molecules in a distorted octahedral geometry. The presence of intermolecular hydrogen bonding and p-p stacking interaction of aromatic rings from 2, 2?bipy results in a 3D structure.展开更多
Quality marker(Q-marker)of Chinese materia medica(CMM)plays an important role in quality control of CMM products.However,its research strategy and technique remain unclear.Based on the fact that quality standard of CM...Quality marker(Q-marker)of Chinese materia medica(CMM)plays an important role in quality control of CMM products.However,its research strategy and technique remain unclear.Based on the fact that quality standard of CMM should be associated with clinical efficacy,taking Jinqi Jiangtang tablet treating type 2 diabetes as an example,the Q-marker related to activity via the reverse analysis of drug metabolism in clinic and traceability of botanic biosynthetic pathways is discovered and validated.Therefore,we proposed a new research strategy of Q-marker of CMM with"Discovery of clinical active constituents as guidance,Reverse analysis of metabolic transformations as link,and Traceability of biosynthesis pathways as key",to improve quality control of CMM products.展开更多
As an oral chemotherapy prodrug,tegafur,can be converted to 5-fluorouracil,which is activated to kill tumor cells mainly by the inhibition of thymidylate synthase.In the present study,we synthesized 20 new tegafur der...As an oral chemotherapy prodrug,tegafur,can be converted to 5-fluorouracil,which is activated to kill tumor cells mainly by the inhibition of thymidylate synthase.In the present study,we synthesized 20 new tegafur derivatives containing amino acid ester groups by substitution,hydrolysis,and condensation.Their structures were confirmed by 1H NMR,13C NMR,and H RMS,and their inhibitory effects on tumor cell growth were studied.The results showed that some of the compounds had good anti-tumor activity.展开更多
This work provides an effective low-cost synthesis and in-depth mechanistic study of high quality large-area nitrogen-doped graphene(NG) films. These films were synthesized using urea as nitrogen source and methane as...This work provides an effective low-cost synthesis and in-depth mechanistic study of high quality large-area nitrogen-doped graphene(NG) films. These films were synthesized using urea as nitrogen source and methane as carbon source, and were characterized by scanning electron microscopy(SEM), Raman spectroscopy and X-ray photoelectron spectroscopy(XPS). The N doping level was determined to be 3.72 at.%, and N atoms were suggested to mainly incorporated in a pyrrolic N configuration. All distinct Raman peaks display a shift due to the nitrogen-doping and compressive strain. The increase in urea concentration broadens the D and 2D peak's Full Width at Half Maximum(FWHM), due to the decrease of mean free path of phonons. The N-doped graphene exhibited an n-type doping behavior with a considerably high carrier mobility of about 74.1 cm2/(V s), confirmed by electrical transport measurements.展开更多
基金Project (51072104) supported by the National Natural Science Foundation of ChinaProject (BS2010CL038) supported by the Research Award Fund for Outstanding Young and Middle-aged Scientists of Shandong Province,China
文摘Open-celled porous NiAl intermetallics with adjustable pore characteristics and mechanical properties were successfully prepared by using spherical carbamide as space-holders via combustion synthesis.Examinations of macroscopic and microscopic morphologies as well as the quasi-static compressive test for the resultant materials were carried out.Depending on the volume fraction and particle size of the carbamide,the porosity and pore size of the porous NiAl intermetallics can be controlled freely in a range of 57.57%-84.58% and 0.4-2.0 mm,respectively.Furthermore,quasi-static compressive tests indicate that the mechanical behavior of the present porous materials is in good agreement with the Gibson-Ashby model.
文摘Chemical doping is an effective method to intrinsically modify the chemical and electronic property of graphene. We propose a novel approach to synthesize the nitrogen-doped graphene via thermal annealing graphene with urea, in which the nitrogen source can be controllably released from the urea by varying the annealed temperature and time. The doped N content and the configuration N as well as the thermal stabilities are also evaluated with X-ray photoelectron spectroscopy and Raman spectra. Electrical measurements indi- cate that the conductivity of doped graphene can be well regulated with the N content. The method is expected to produce large scale and controllable N-doped graphene sheets for a variety of potential applications.
文摘A novel bead form of ploymer of high sorption capacity for urea were obtained by the reaction of glutaric dialdehyde wigh chitosan dispersed in acetic acid solution. The sorption capacity reached ￣ 82.0 mg / g sorbent at 37℃ and pH 7.4 The concentration of urea in the buffer solution was 1300 mg/ L. The sorption of urea was related to the degree of crosslinking of the sorbent, concentration ofurea, ionic strength and temperature.
基金Supported by the National Natural Science Foundation of China （20976035, 21076059） the Natural Science Foundation of Hebei Province （B2010000019）
文摘Toluene-2,4-bisurea (TBU) is an important intermediate for urea route to dimethyl toluene-2,4-dicarbamate and the study on TBU synthesis via the reaction of 2,4-toluene diamine (TDA) and urea is of great significance. Firstly, thermodynamic analysis shows that the reaction is exothermic and a high equilibrium conversion of TDA is expected due to its large reaction equilibrium constant. Secondly, under the suitable reaction conditions, 130 °C, 7 h, and molar ratio of TDA/zinc acetate/urea/sulfolane 1/0.05/3.5/10, TDA conversion is 54.3%, and TBU yield and selectivity are 39.8% and 73.3% respectively. Lastly, the synthesis of TBU is a 1st order reaction with respect to TDA and the reaction kinetics model is established. This work will provide useful information for commercializing the urea route to toluene-2,4-dicarbamate (TDC).
基金Supported by the Changcheng Scholars Program of Beijing(CIT&TCD 20150316)
文摘A series of Zn–Ca–Al oxides with different CaO and ZnO contents have been prepared and evaluated in the synthesis of propylene carbonate(PC) from 1,2-propylene glycol(PG) and urea in a batch reactor. The effect of catalyst composition, basicity and reaction process parameters such as temperature, catalyst dose, molar ratio of PG to urea, purge gas flow and reaction time has been studied to find suitable reaction conditions for the PC synthesis. The PC selectivity and yield under the desired conditions could reach 98.4% and 90.8%, respectively. The best performing catalyst also exhibited a good reusability without appreciable loss in the PC selectivity and yield after five consecutive reaction runs. In addition, a stepwise reaction pathway involving a 2-hydroxypropyl carbamate intermediate was proposed for the urea alcoholysis to PC in the presence of Zn–Ca–Al catalysts, according to the time dependences of reaction intermediates and products.
基金This project was supported by the Natural Science Foundation of China and Chinese Academy of Sciences
文摘The crystal structure of [Ni(C5H2N2O4)(2, 2?bipy)(H2O)2]?H2O 1 has been determined by X-ray diffraction. Crystal data: triclinic system, space group P with a = 7.9424(3), b = 9.9417(3), c = 12.1867(3) ? a = 84.771(1), b = 77.375(2), g = 68.993(2)? C15H18N4O8Ni, Mr = 440.7, V = 876.16(5) 3, Z = 2, Dc = 1.672 g/cm3, F(000) = 456, m(MoKa) = 1.162 mm-1, the final R = 0.0464 and wR = 0.1055 for 3026 observed reflections with I > 2s(I). In the title compound, the nickel ion is coordinated by a nitrogen atom and an oxygen atom from the orotate ligand, two nitrogen atoms from 2, 2?bipy and two oxygen atoms from the coordinated water molecules in a distorted octahedral geometry. The presence of intermolecular hydrogen bonding and p-p stacking interaction of aromatic rings from 2, 2?bipy results in a 3D structure.
基金the National Natural Science Foundation of China(81773891)the National Great New Drugs Development Project of China(2017ZX09301-040)+3 种基金the Beijing Natural Science Foundation(7162092)Beijing Talents Project(2017A19)Beijing Municipal Science&Technology Commission(XMLX201704,Z161100000516074)the Open Research Fund of the State Key Laboratory Breeding Base of Systematic Research,Development and Utilization of Chinese Medicinal Resources.
文摘Quality marker(Q-marker)of Chinese materia medica(CMM)plays an important role in quality control of CMM products.However,its research strategy and technique remain unclear.Based on the fact that quality standard of CMM should be associated with clinical efficacy,taking Jinqi Jiangtang tablet treating type 2 diabetes as an example,the Q-marker related to activity via the reverse analysis of drug metabolism in clinic and traceability of botanic biosynthetic pathways is discovered and validated.Therefore,we proposed a new research strategy of Q-marker of CMM with"Discovery of clinical active constituents as guidance,Reverse analysis of metabolic transformations as link,and Traceability of biosynthesis pathways as key",to improve quality control of CMM products.
基金Science and Technology Program of Shandong Academy of Medical Sciences(Grant No.2016-5)National Innovation and Entrepreneurship Training Program for College Students(Grant No.201810427013)。
文摘As an oral chemotherapy prodrug,tegafur,can be converted to 5-fluorouracil,which is activated to kill tumor cells mainly by the inhibition of thymidylate synthase.In the present study,we synthesized 20 new tegafur derivatives containing amino acid ester groups by substitution,hydrolysis,and condensation.Their structures were confirmed by 1H NMR,13C NMR,and H RMS,and their inhibitory effects on tumor cell growth were studied.The results showed that some of the compounds had good anti-tumor activity.
基金supported by the National Natural Science Foundation of China(Grant Nos.91123009,10975115)the Natural Science Foundation of Fujian Province of China(Grant No.2012J06002)
文摘This work provides an effective low-cost synthesis and in-depth mechanistic study of high quality large-area nitrogen-doped graphene(NG) films. These films were synthesized using urea as nitrogen source and methane as carbon source, and were characterized by scanning electron microscopy(SEM), Raman spectroscopy and X-ray photoelectron spectroscopy(XPS). The N doping level was determined to be 3.72 at.%, and N atoms were suggested to mainly incorporated in a pyrrolic N configuration. All distinct Raman peaks display a shift due to the nitrogen-doping and compressive strain. The increase in urea concentration broadens the D and 2D peak's Full Width at Half Maximum(FWHM), due to the decrease of mean free path of phonons. The N-doped graphene exhibited an n-type doping behavior with a considerably high carrier mobility of about 74.1 cm2/(V s), confirmed by electrical transport measurements.
