Ribosomally synthesized and post-translationally modified peptides(RiPPs)constitute a vast and diverse family of bioactive peptides.These peptides,synthesized by ribosomes and subsequently modified by various tailorin...Ribosomally synthesized and post-translationally modified peptides(RiPPs)constitute a vast and diverse family of bioactive peptides.These peptides,synthesized by ribosomes and subsequently modified by various tailoring enzymes,possess a wide chemical space.Among these modifications,radical S-adenosylmethionine(rSAM)enzymes employ unique radical chemistry to introduce a variety of novel peptide structures,which are crucial for their activity.This review examines the major types of modifications in RiPPs catalyzed by rSAM enzymes,incorporating recent advancements in protein structure analysis techniques and computational methods.Additionally,it elucidates the diverse catalytic mechanisms and substrate selectivity of these enzymes through an analysis of the latest crystal structures.展开更多
Radiotherapy has played an important role in treatment of tumor patientssince it appeared about 80 years ago, and has been an indispensable part of the management of about50% of tumors (especially 60% - 70% of maligna...Radiotherapy has played an important role in treatment of tumor patientssince it appeared about 80 years ago, and has been an indispensable part of the management of about50% of tumors (especially 60% - 70% of malignant tumors). Currently, radiotherapy is used in simpleand palliative therapy, adjuvant therapy after or before surgery, simultaneous radio-chemotherapy,combined BRM (biological response modifier) therapy, ets. Radiosensitizing agents enhance theradiation effects on tumor cells so as to have better responses in radiotherapy. Tumor intrinsicradiosensitivity is affected by the hy-poxic level in solid tumor, the ability of the cells torepair the radiation-induced DNA damage, the number of cells which have a clonogenic capability toreestablish uncontrolled cell growth, the amount of dividing cells, and the distribution of cellsthroughout the cell cycle. Consequently , it is necessary and useful to add one or moreradiosensitizing agents in radiotherapy to increase the radio-sensitivity of tumor cells.展开更多
It was shown by TEM and X-ray analysis that there are four types of grains of the main Ni3Al phase in the structure of the intermetallic obtained by the self-propagation high temperature method (SHS). Every type of gr...It was shown by TEM and X-ray analysis that there are four types of grains of the main Ni3Al phase in the structure of the intermetallic obtained by the self-propagation high temperature method (SHS). Every type of grains has its own domain and dislocation structure. There are mono- and polydomains with and without dislocations. The grains of the main phase of monoand polydomains without dislocations and polydomains with dislocations were formed by diffusion in the solid phase. In these conditions NiAl3 phase is located on the grain boundary of the main phase. The Ni2Al3 phase is located at the triple joints of the main phase.展开更多
Tin oxide （SnO2） is one of the most promising transparent conducting oxide materials, which is widely used in thin film gas sensors. We investigate the dependence of the deposition time on structural, morphologicaJ ...Tin oxide （SnO2） is one of the most promising transparent conducting oxide materials, which is widely used in thin film gas sensors. We investigate the dependence of the deposition time on structural, morphologicaJ and hydrogen gas sensing properties of SnO2 thin films synthesized by dc magnetron sputtering. The deposited samples are characterized by XRD, SEM, AFM, surface area measurements and surface profiler. Also the H2 gas sensing properties of SnO2 deposited samples are performed against a wide range of operating temperature. The XRD analysis demonstrates that the degree of crystallinity of the deposited SnO2 films strongly depends on the deposition time. SEM and AFM analyses reveal that the size of nanoparticles or agglomerates, and both average and rms surface roughness is enhanced with the increasing deposition time. Also gas sensors based on these SnO2 nanolayers show an acceptable response to hydrogen at various operating temperatures.展开更多
The synthesis of diamond single crystal in the Fe64Ni36-C system with h-BN additive is investigated at pressure 6.5 GPa and temperature range of 1300-1400℃. The color of the obtained diamond crystals translates from ...The synthesis of diamond single crystal in the Fe64Ni36-C system with h-BN additive is investigated at pressure 6.5 GPa and temperature range of 1300-1400℃. The color of the obtained diamond crystals translates from yellow to dark green with increasing the h-BN addition. Fourier-transform infrared （FTIR） results indicate that sp2 hybridization B-N-B and B-N structures generate when the additive content reaches a certain value in the system. The two peaks are located at 745 and 1425cm-1, respectively. Fhrthermore, the FTIR characteristic peak resulting from nitrogen pairs is noticed and it tends to vanish when the h-BN addition reaches 1.1 wt%. Furthermore, Raman peak of the synthesized diamond shifts down to a lower wavenumber with increasing the h-BN ~ddition content in the synthesis system.展开更多
The in situ synthesized MoSi2-SiC composite is proved to be of higher fracture toughness than the monolithic MoSi2. The TEM and HREM study reveals that the interface between MoSi2/SiC is of direct atomic bonding witho...The in situ synthesized MoSi2-SiC composite is proved to be of higher fracture toughness than the monolithic MoSi2. The TEM and HREM study reveals that the interface between MoSi2/SiC is of direct atomic bonding without any amorphous glassy phase, such the SiO2 structure. Based on the fractography and the observation of crack propagation path from indentation, it is concluded that the toughening of such composite at room temperature can be attributed to the high interfacial binding energy, the refinement of the MoSi2 matrix and the deflection and bridging behavior in the crack propagation.展开更多
Synthesized allopolyploids are valuable materials for comparative analyses of two or more distinct genomes, such as the expression changes （activation, inactivation or differential expression） of orthologous genes f...Synthesized allopolyploids are valuable materials for comparative analyses of two or more distinct genomes, such as the expression changes （activation, inactivation or differential expression） of orthologous genes following allopolyploidization. CENH3 is a centromerespecific histone H3 variant and has been regarded as a central component in kinetochore formation and centromere function. In this study, interspecific hybrids of Oryza genus （AA × CC, AA × CCDD） and their backcross progenies were produced, and the genome constitutions were identified as AC, ACC, ACD, AACD, or AA（CD） by Genomic in situ hybridization （GISH）. We further cloned and sequenced the CENH3 genes from O. sativa （AA）, O. officinalis （CC） and O. latifolia （CCDD）. Sequencing of RT-PCR products revealed that CENH3_C2 and CENH3_D, the two CENH3 alleles from O. latifolia, showed polymophism in several sites, while CENH3_C2 and CENH3_C1 from O. officinalis were different at only two amino acids positions. Moreover, we found that the CENH3 genes from both parents are expressed in interspecific hybrids and their progenies. Specifically, based on our cDNA sequencing data, the ratio of expres- sion level between CENH3_A and CENH3_C1 was approximately 1 in AC and 0.5 in ACC genomes, respectively. As a result, the CENH3 expression patterns shed more light on the inter-coordination between varied centromeric DNA sequences and highly conserved kinetochore protein in synthesized allopolyploids of Oryza genus.展开更多
A Ti-BN complex cathode is made from Ti and h-BN powders by the powder metallurgy technology, and TiBN coating is obtained by plasma immersion ion implantation and deposition with this Ti-BN composite cathode. The TiB...A Ti-BN complex cathode is made from Ti and h-BN powders by the powder metallurgy technology, and TiBN coating is obtained by plasma immersion ion implantation and deposition with this Ti-BN composite cathode. The TiBN coating shows a self-forming multilayered nanocomposite structure while with relative uniform elemental distributions. High resolution transmission electron microscopy images reveal that the multilayered structure is derived from different grain sizes in the nanocomposite. Due to the existence of h-BN phase, the friction coefficient of the coating is about 0.25.展开更多
The Ni_3B phase was formed when boron (0.5 at. pct B) was added to the intermetallic of sto- ichiometric and off-stoichiometric (Ni-24 at. pct Al) compounds. In the alloy of stoichiometric composition the particles o...The Ni_3B phase was formed when boron (0.5 at. pct B) was added to the intermetallic of sto- ichiometric and off-stoichiometric (Ni-24 at. pct Al) compounds. In the alloy of stoichiometric composition the particles of Ni_3B phase has the size around 0.1μm and is located on the grain boundary of the main phase. The decreasing of concentrations of Al in the ofF-stoichiometric alloy leads to increase in the degree of the long-range order parameter, increasing the concen- trations of boron in the solid solution and decreasing its localization on the grain boundary. Microalloying of boron leads to increasing in the fraction of grain monodomains with disloca- tions up to 0.7 in the alloy of the off-stoichiometric composition and up to 1 in the alloy of the stoichiometric composition. It was established the correlation between the degree of the concentration inhomogeneity, average density of the dislocations and the average long range-order parameter.展开更多
The use of the four new synthesized polyurethane acrylate binders in the pigment print paste for screen printing cotton and polyester fabrics and pigment fixation through the polymerization process of the binder by us...The use of the four new synthesized polyurethane acrylate binders in the pigment print paste for screen printing cotton and polyester fabrics and pigment fixation through the polymerization process of the binder by using the thermofixation technique as well as the UV curing technique was studied. The effect of changing time and temperature of thermofixation, and the time of UV curing on the color strength, and prints fastness properties were also studied. The results showed that, the newly synthesized polyurethane acrylate binders could be successfully used for pigment fixation on cotton and polyester using the two fixation techniques and in general their prints possessed better color strength values as compared to those obtained upon using the selected commercial binders.展开更多
Nano-composite particles can be synthesized by a hydrogen arc plasma method, which possesses the advantages of high productivity, controllable size distribution and low electric energy consumption comparing with conve...Nano-composite particles can be synthesized by a hydrogen arc plasma method, which possesses the advantages of high productivity, controllable size distribution and low electric energy consumption comparing with conventional gas condensation method. With this method, not only the nanoparticles of metals and alloys, but also the nano-composite particles with shell structure can be synthesized. The microstructures, compositions and the formation mechanism of the nano composite particles were studied展开更多
Triangular mesh is often used to describe geometric object as computed model in digital manufacture,thus the mesh model with both uniform triangular shape and excellent geometric shape is expected.But in fact,the opti...Triangular mesh is often used to describe geometric object as computed model in digital manufacture,thus the mesh model with both uniform triangular shape and excellent geometric shape is expected.But in fact,the optimization of triangu- lar shape often is contrary with that of geometric shape.In this paper,one synthesized optimizing algorithm is presented through subdividing triangles to achieve the trade-off solution between the geometric and triangular shape optimization of mesh model.The result mesh with uniform triangular shape and excellent topology are obtained.展开更多
Objective: To investigate the antiviral property of a lead ligand, YK51 that was synthesized based on the flavanoid of a natural product toward dengue virus type-2(DENV2)replication.Methods: c RNA was isolated from He...Objective: To investigate the antiviral property of a lead ligand, YK51 that was synthesized based on the flavanoid of a natural product toward dengue virus type-2(DENV2)replication.Methods: c RNA was isolated from HepG2 cells inoculated with 1 000 median tissue culture infective dose of DENV2 and treated with different doses of the ligand followed by RT-PCR to quantify the virus gene copies. Confocal microscopy of actin and tubulin redistribution was also performed.Results: The quantitative RT-PCR result showed reduction of the DENV2 gene copies as the ligand concentration was increased. The confocal microscopy result showed increase in the tubulin intensity(79.6%) of infected BHK21 cells treated with the ligand,compared with the non-treated cells(54.8%). The 1.5-fold increase in the intensity of tubulin suggested that the ligand inhibitory effect stabilized the cellular microtubule structure.Conclusions: The synthesized ligand YK51 reduced DENV2 viral load by inhibiting virus replication thus is highly potential to be developed as antiviral agent.展开更多
In situ synthesized MgAl2O4whiskers reinforced 6061 Al alloy composites were fabricated by a powder metallurgy method.Nano-sized MgAl2O4spinel whiskers distributed uniformly in 6061 Al alloy matrix without any interfa...In situ synthesized MgAl2O4whiskers reinforced 6061 Al alloy composites were fabricated by a powder metallurgy method.Nano-sized MgAl2O4spinel whiskers distributed uniformly in 6061 Al alloy matrix without any interfacial product and laid along the extrusion direction after hot extrusion.As-extruded composite samples were annealed at 530,580,600 and 630℃for 1 h and examined by electron backscattered diffraction to investigate the recrystallization behavior of obtained composites.Microstructure and texture evolution was investigated,and it is found that the recrystallization process is inhibited by whiskers because of Zener pinning.Slender fibrous grains remain until 630℃,and deformation textures still exist even in specimen annealed at 630℃.Hardness and tensile tests show that the completely recrystallized sample has an ultimate tensile strength of 218 MPa and a hardness of HV52 compared with 283 MPa and HV 69 of the unannealed sample.Mechanical properties of the annealed samples decline slightly with annealing temperature increasing up to 600℃.展开更多
In this peper we have synthesized powder crystal form (Y,Gd) BO3:Eu(3+)Phosphors by microwave heating method. ItS structure belongs to hexagonal system with lattice parameters a=0.3796,c=0. 8835. Its excitation spetra...In this peper we have synthesized powder crystal form (Y,Gd) BO3:Eu(3+)Phosphors by microwave heating method. ItS structure belongs to hexagonal system with lattice parameters a=0.3796,c=0. 8835. Its excitation spetra peaks at 239.0nm and 240. 0nm monitored at the emission of 589nm and 612nm respectively, the half peak width is 40nm. Under 240nm excitation the phosphors show a strons oranse-red luminescence, the fluorescent intensity ratio for I589/I612 is 1.9/1展开更多
ZrO2/Graphene nanocomposites are fabricated from graphene oxide by one-step, green, facile and low-cost SCCO2 method. The as-prepared nanocomposites are characterized by means of X-ray photoelectron, transmission elec...ZrO2/Graphene nanocomposites are fabricated from graphene oxide by one-step, green, facile and low-cost SCCO2 method. The as-prepared nanocomposites are characterized by means of X-ray photoelectron, transmission electron microscopy and catalytic chemiluminescence measurement. The ZrO2 nanoparticles with size of several nanometers are uniformly coated on the graphene surface. The chemiluminescence characteristic to ethanol of the as-prepared nanocomposite paper is also investigated. The nanocomposite paper obtained displays high catalytic chemiluminescence sensitivity and highly selectivity to the ethanol gas. This study provides a facile, green and low-cost route to prepare nanoscopic gas sensing devices with application in safe protection, food fermentation, medical process and traffic safe.展开更多
The crystallization behaviour of the laser synthesized nanometric amorphous Si3N4 powders with the particle size of 15 nm in diameter has been studied between 1200° and 1700℃ by XRD,TEM and FTIR techniques. A sm...The crystallization behaviour of the laser synthesized nanometric amorphous Si3N4 powders with the particle size of 15 nm in diameter has been studied between 1200° and 1700℃ by XRD,TEM and FTIR techniques. A small amount of β-Si3N4 formed at 1250℃ and increased slowly until the α- β transformation happened at 1700℃, whereas α-Si3N4 appeared at 1300℃ andincreased rapidly between 1500-1600℃. The formation of β phase at the lower temperature was caused by the nitridation of free Si due to the preexisted β-nuclei in the Si3N4 particles, whereasthe α phase was formed by solid crystallization from the amorphous matrix. There were α and β SiC formed at 1700℃ due to the presence of Sio and Co gases in the system. FTIR analysis shows that two new IR absorption at 1356 and 1420 cm-1, and an overall strong absorption in wide wavenumber range resulted from the powders annealed at 1600 and 1700℃ respectively展开更多
Gamma irradiation is employed for in situ preparation of PVA-PANI-ZnS nanocomposite. The irradiation dose is varied from 10 to 40 kGy at 10 kGy intervals. The XRD result confirms the formation of crystalline phases co...Gamma irradiation is employed for in situ preparation of PVA-PANI-ZnS nanocomposite. The irradiation dose is varied from 10 to 40 kGy at 10 kGy intervals. The XRD result confirms the formation of crystalline phases corresponding to ZnS nanoparticles, PVA and PANI. Field emission scanning electron microscopy shows the formation of agglomerated PANI along the PVA backbone, within which the ZnS nanoparticles are dispersed.UV-visible spectroscopy is conducted to measure the transmittance spectra of samples revealing the electronic absorption characteristics of ZnS and PANI nanoparticles. Photo-acoustic（PA） setup is installed to investigate the thermal properties of samples. The PA spectroscopy indicates a high value of thermal diffusivity for samples due to the presence of ZnS and PANI nanoparticles. Moreover, at higher doses, the more polymerization and formation of PANI and ZnS nanoparticles result in enhancement of thermal diffusivity.展开更多
The differential thermal analysis （DTA） curves were measured at different heating rates in flowing air for studying the synthesis of the spinel LiMn2O3 with Li2CO3 and MnO2, The reaction began at about 503K, and fin...The differential thermal analysis （DTA） curves were measured at different heating rates in flowing air for studying the synthesis of the spinel LiMn2O3 with Li2CO3 and MnO2, The reaction began at about 503K, and finished at about 873K. The apparent activation energy of Kissinger method was about 122.77kJ.mol^-1, the reaction orderwas 1.67, the frequency factor was 7.81×10^9, and therefore the dinetic epuation was dδ/dt=A·exp（- E/RT）·（1-δ）^n=7.81×10^9, exp（-122770/RT）·（l-δ）^1.67 . Coats-Redfem integral method was used to analyze the DTA curves of the samples at different heating rates, and the calculated apparent activation energy and frequency factor were 112. 13kJ· mol^-1 and 1.18 × 10^9, respectively, rather close to that of Kissinger method. X-ray diffraction （XRD） and scanning electron microscope （SEM） results shown that the synthesized LiMn2O3 possesses pure phase, regular shape and normal particle distribution.展开更多
The chemical compositions of the sludge after treatment are tested by fully chemical analysis techniques. Its crystalline phase structure changes of the sludge calcined at different temperature are characterized by XR...The chemical compositions of the sludge after treatment are tested by fully chemical analysis techniques. Its crystalline phase structure changes of the sludge calcined at different temperature are characterized by XRD method. Nitrogen gas isothermal adsorption method （77 K） is applied to measure the influences of ammonium bicarbonate on specific surface area and pore structure of activated alumina synthesized from waste aluminum sludge. The result shows that the amount of Al2O3 in the sludge accounts for more than 94%, and Na2Owt% in a 0.1-0.2% range. By calcining raw sludge at 600℃, monophase γ-Al2O3 is obtained. And this can satisfy the performance requirements of activated alumina adsorbent. The specific surface area of the specimen with NH4HCO3 added has expanded from 179 to 249 m^2/g and the pore volume from 0.25 to 1.11 cm^3/g as well as the average pore diameter from 5.6 to 17.8 nm. All these show that NH4HCO3 is an effective pore-expansion agent to remarkably improve the structure and performance of activated alumina synthesized from waste aluminum sludge.展开更多
基金supported by the National Key Research and Development Program of China(No.2023YFA0916000)the National Natural Science Foundation of China(No.32371324)the High-level Talent Startup Fund provided by China Pharmaceutical University.
文摘Ribosomally synthesized and post-translationally modified peptides(RiPPs)constitute a vast and diverse family of bioactive peptides.These peptides,synthesized by ribosomes and subsequently modified by various tailoring enzymes,possess a wide chemical space.Among these modifications,radical S-adenosylmethionine(rSAM)enzymes employ unique radical chemistry to introduce a variety of novel peptide structures,which are crucial for their activity.This review examines the major types of modifications in RiPPs catalyzed by rSAM enzymes,incorporating recent advancements in protein structure analysis techniques and computational methods.Additionally,it elucidates the diverse catalytic mechanisms and substrate selectivity of these enzymes through an analysis of the latest crystal structures.
文摘Radiotherapy has played an important role in treatment of tumor patientssince it appeared about 80 years ago, and has been an indispensable part of the management of about50% of tumors (especially 60% - 70% of malignant tumors). Currently, radiotherapy is used in simpleand palliative therapy, adjuvant therapy after or before surgery, simultaneous radio-chemotherapy,combined BRM (biological response modifier) therapy, ets. Radiosensitizing agents enhance theradiation effects on tumor cells so as to have better responses in radiotherapy. Tumor intrinsicradiosensitivity is affected by the hy-poxic level in solid tumor, the ability of the cells torepair the radiation-induced DNA damage, the number of cells which have a clonogenic capability toreestablish uncontrolled cell growth, the amount of dividing cells, and the distribution of cellsthroughout the cell cycle. Consequently , it is necessary and useful to add one or moreradiosensitizing agents in radiotherapy to increase the radio-sensitivity of tumor cells.
文摘It was shown by TEM and X-ray analysis that there are four types of grains of the main Ni3Al phase in the structure of the intermetallic obtained by the self-propagation high temperature method (SHS). Every type of grains has its own domain and dislocation structure. There are mono- and polydomains with and without dislocations. The grains of the main phase of monoand polydomains without dislocations and polydomains with dislocations were formed by diffusion in the solid phase. In these conditions NiAl3 phase is located on the grain boundary of the main phase. The Ni2Al3 phase is located at the triple joints of the main phase.
基金Supported by the Bandar Abbas Branch of the Islamic Azad University
文摘Tin oxide （SnO2） is one of the most promising transparent conducting oxide materials, which is widely used in thin film gas sensors. We investigate the dependence of the deposition time on structural, morphologicaJ and hydrogen gas sensing properties of SnO2 thin films synthesized by dc magnetron sputtering. The deposited samples are characterized by XRD, SEM, AFM, surface area measurements and surface profiler. Also the H2 gas sensing properties of SnO2 deposited samples are performed against a wide range of operating temperature. The XRD analysis demonstrates that the degree of crystallinity of the deposited SnO2 films strongly depends on the deposition time. SEM and AFM analyses reveal that the size of nanoparticles or agglomerates, and both average and rms surface roughness is enhanced with the increasing deposition time. Also gas sensors based on these SnO2 nanolayers show an acceptable response to hydrogen at various operating temperatures.
基金Supported by the National Natural Science Foundation of China under Grant No 51172089the Natural Science Foundation of Guizhou Province Education Department under Grant No KY[2013]183the Natural Science Foundation of Guizhou Province Science and Technology Agency under Grant Nos LH[2015]7232 and LH[2015]7228
文摘The synthesis of diamond single crystal in the Fe64Ni36-C system with h-BN additive is investigated at pressure 6.5 GPa and temperature range of 1300-1400℃. The color of the obtained diamond crystals translates from yellow to dark green with increasing the h-BN addition. Fourier-transform infrared （FTIR） results indicate that sp2 hybridization B-N-B and B-N structures generate when the additive content reaches a certain value in the system. The two peaks are located at 745 and 1425cm-1, respectively. Fhrthermore, the FTIR characteristic peak resulting from nitrogen pairs is noticed and it tends to vanish when the h-BN addition reaches 1.1 wt%. Furthermore, Raman peak of the synthesized diamond shifts down to a lower wavenumber with increasing the h-BN ~ddition content in the synthesis system.
基金the National Natural Science Foundation of China (No. 59895150-04-02).
文摘The in situ synthesized MoSi2-SiC composite is proved to be of higher fracture toughness than the monolithic MoSi2. The TEM and HREM study reveals that the interface between MoSi2/SiC is of direct atomic bonding without any amorphous glassy phase, such the SiO2 structure. Based on the fractography and the observation of crack propagation path from indentation, it is concluded that the toughening of such composite at room temperature can be attributed to the high interfacial binding energy, the refinement of the MoSi2 matrix and the deflection and bridging behavior in the crack propagation.
基金supported by the Natural Science Foundation of China (No. 31025018)by the Program for National Transgenic Research Program of China (No. 2009ZX08010-00313) to W.W. Jin.
文摘Synthesized allopolyploids are valuable materials for comparative analyses of two or more distinct genomes, such as the expression changes （activation, inactivation or differential expression） of orthologous genes following allopolyploidization. CENH3 is a centromerespecific histone H3 variant and has been regarded as a central component in kinetochore formation and centromere function. In this study, interspecific hybrids of Oryza genus （AA × CC, AA × CCDD） and their backcross progenies were produced, and the genome constitutions were identified as AC, ACC, ACD, AACD, or AA（CD） by Genomic in situ hybridization （GISH）. We further cloned and sequenced the CENH3 genes from O. sativa （AA）, O. officinalis （CC） and O. latifolia （CCDD）. Sequencing of RT-PCR products revealed that CENH3_C2 and CENH3_D, the two CENH3 alleles from O. latifolia, showed polymophism in several sites, while CENH3_C2 and CENH3_C1 from O. officinalis were different at only two amino acids positions. Moreover, we found that the CENH3 genes from both parents are expressed in interspecific hybrids and their progenies. Specifically, based on our cDNA sequencing data, the ratio of expres- sion level between CENH3_A and CENH3_C1 was approximately 1 in AC and 0.5 in ACC genomes, respectively. As a result, the CENH3 expression patterns shed more light on the inter-coordination between varied centromeric DNA sequences and highly conserved kinetochore protein in synthesized allopolyploids of Oryza genus.
基金Supported by the Fund of National Key Laboratory of High Power Microwave Technology under Grant No 2014-763.xy.kthe National Natural Science Foundation of China under Grant No 21573054the Joint Funds Key Project of the National Natural Science Foundation of China under Grant No U1537214
文摘A Ti-BN complex cathode is made from Ti and h-BN powders by the powder metallurgy technology, and TiBN coating is obtained by plasma immersion ion implantation and deposition with this Ti-BN composite cathode. The TiBN coating shows a self-forming multilayered nanocomposite structure while with relative uniform elemental distributions. High resolution transmission electron microscopy images reveal that the multilayered structure is derived from different grain sizes in the nanocomposite. Due to the existence of h-BN phase, the friction coefficient of the coating is about 0.25.
文摘The Ni_3B phase was formed when boron (0.5 at. pct B) was added to the intermetallic of sto- ichiometric and off-stoichiometric (Ni-24 at. pct Al) compounds. In the alloy of stoichiometric composition the particles of Ni_3B phase has the size around 0.1μm and is located on the grain boundary of the main phase. The decreasing of concentrations of Al in the ofF-stoichiometric alloy leads to increase in the degree of the long-range order parameter, increasing the concen- trations of boron in the solid solution and decreasing its localization on the grain boundary. Microalloying of boron leads to increasing in the fraction of grain monodomains with disloca- tions up to 0.7 in the alloy of the off-stoichiometric composition and up to 1 in the alloy of the stoichiometric composition. It was established the correlation between the degree of the concentration inhomogeneity, average density of the dislocations and the average long range-order parameter.
文摘The use of the four new synthesized polyurethane acrylate binders in the pigment print paste for screen printing cotton and polyester fabrics and pigment fixation through the polymerization process of the binder by using the thermofixation technique as well as the UV curing technique was studied. The effect of changing time and temperature of thermofixation, and the time of UV curing on the color strength, and prints fastness properties were also studied. The results showed that, the newly synthesized polyurethane acrylate binders could be successfully used for pigment fixation on cotton and polyester using the two fixation techniques and in general their prints possessed better color strength values as compared to those obtained upon using the selected commercial binders.
文摘Nano-composite particles can be synthesized by a hydrogen arc plasma method, which possesses the advantages of high productivity, controllable size distribution and low electric energy consumption comparing with conventional gas condensation method. With this method, not only the nanoparticles of metals and alloys, but also the nano-composite particles with shell structure can be synthesized. The microstructures, compositions and the formation mechanism of the nano composite particles were studied
基金Supported by the National Nature Science Foundation of China under Grant No 50335020the National Basic Research Progra of China under Grant No 2006CB705400
文摘Triangular mesh is often used to describe geometric object as computed model in digital manufacture,thus the mesh model with both uniform triangular shape and excellent geometric shape is expected.But in fact,the optimization of triangu- lar shape often is contrary with that of geometric shape.In this paper,one synthesized optimizing algorithm is presented through subdividing triangles to achieve the trade-off solution between the geometric and triangular shape optimization of mesh model.The result mesh with uniform triangular shape and excellent topology are obtained.
基金Supported by Science Fund from the Ministry of Science,Technology and Innovation Malaysia and Research Acculturation Grants of Universiti Teknologi MARA(UiTM)[RAGS/2012/Ui TM/ST04/1],Malaysia
文摘Objective: To investigate the antiviral property of a lead ligand, YK51 that was synthesized based on the flavanoid of a natural product toward dengue virus type-2(DENV2)replication.Methods: c RNA was isolated from HepG2 cells inoculated with 1 000 median tissue culture infective dose of DENV2 and treated with different doses of the ligand followed by RT-PCR to quantify the virus gene copies. Confocal microscopy of actin and tubulin redistribution was also performed.Results: The quantitative RT-PCR result showed reduction of the DENV2 gene copies as the ligand concentration was increased. The confocal microscopy result showed increase in the tubulin intensity(79.6%) of infected BHK21 cells treated with the ligand,compared with the non-treated cells(54.8%). The 1.5-fold increase in the intensity of tubulin suggested that the ligand inhibitory effect stabilized the cellular microtubule structure.Conclusions: The synthesized ligand YK51 reduced DENV2 viral load by inhibiting virus replication thus is highly potential to be developed as antiviral agent.
基金financially supported by the National Natural Science Foundation of China(No.51571147)。
文摘In situ synthesized MgAl2O4whiskers reinforced 6061 Al alloy composites were fabricated by a powder metallurgy method.Nano-sized MgAl2O4spinel whiskers distributed uniformly in 6061 Al alloy matrix without any interfacial product and laid along the extrusion direction after hot extrusion.As-extruded composite samples were annealed at 530,580,600 and 630℃for 1 h and examined by electron backscattered diffraction to investigate the recrystallization behavior of obtained composites.Microstructure and texture evolution was investigated,and it is found that the recrystallization process is inhibited by whiskers because of Zener pinning.Slender fibrous grains remain until 630℃,and deformation textures still exist even in specimen annealed at 630℃.Hardness and tensile tests show that the completely recrystallized sample has an ultimate tensile strength of 218 MPa and a hardness of HV52 compared with 283 MPa and HV 69 of the unannealed sample.Mechanical properties of the annealed samples decline slightly with annealing temperature increasing up to 600℃.
文摘In this peper we have synthesized powder crystal form (Y,Gd) BO3:Eu(3+)Phosphors by microwave heating method. ItS structure belongs to hexagonal system with lattice parameters a=0.3796,c=0. 8835. Its excitation spetra peaks at 239.0nm and 240. 0nm monitored at the emission of 589nm and 612nm respectively, the half peak width is 40nm. Under 240nm excitation the phosphors show a strons oranse-red luminescence, the fluorescent intensity ratio for I589/I612 is 1.9/1
文摘ZrO2/Graphene nanocomposites are fabricated from graphene oxide by one-step, green, facile and low-cost SCCO2 method. The as-prepared nanocomposites are characterized by means of X-ray photoelectron, transmission electron microscopy and catalytic chemiluminescence measurement. The ZrO2 nanoparticles with size of several nanometers are uniformly coated on the graphene surface. The chemiluminescence characteristic to ethanol of the as-prepared nanocomposite paper is also investigated. The nanocomposite paper obtained displays high catalytic chemiluminescence sensitivity and highly selectivity to the ethanol gas. This study provides a facile, green and low-cost route to prepare nanoscopic gas sensing devices with application in safe protection, food fermentation, medical process and traffic safe.
文摘The crystallization behaviour of the laser synthesized nanometric amorphous Si3N4 powders with the particle size of 15 nm in diameter has been studied between 1200° and 1700℃ by XRD,TEM and FTIR techniques. A small amount of β-Si3N4 formed at 1250℃ and increased slowly until the α- β transformation happened at 1700℃, whereas α-Si3N4 appeared at 1300℃ andincreased rapidly between 1500-1600℃. The formation of β phase at the lower temperature was caused by the nitridation of free Si due to the preexisted β-nuclei in the Si3N4 particles, whereasthe α phase was formed by solid crystallization from the amorphous matrix. There were α and β SiC formed at 1700℃ due to the presence of Sio and Co gases in the system. FTIR analysis shows that two new IR absorption at 1356 and 1420 cm-1, and an overall strong absorption in wide wavenumber range resulted from the powders annealed at 1600 and 1700℃ respectively
文摘Gamma irradiation is employed for in situ preparation of PVA-PANI-ZnS nanocomposite. The irradiation dose is varied from 10 to 40 kGy at 10 kGy intervals. The XRD result confirms the formation of crystalline phases corresponding to ZnS nanoparticles, PVA and PANI. Field emission scanning electron microscopy shows the formation of agglomerated PANI along the PVA backbone, within which the ZnS nanoparticles are dispersed.UV-visible spectroscopy is conducted to measure the transmittance spectra of samples revealing the electronic absorption characteristics of ZnS and PANI nanoparticles. Photo-acoustic（PA） setup is installed to investigate the thermal properties of samples. The PA spectroscopy indicates a high value of thermal diffusivity for samples due to the presence of ZnS and PANI nanoparticles. Moreover, at higher doses, the more polymerization and formation of PANI and ZnS nanoparticles result in enhancement of thermal diffusivity.
文摘The differential thermal analysis （DTA） curves were measured at different heating rates in flowing air for studying the synthesis of the spinel LiMn2O3 with Li2CO3 and MnO2, The reaction began at about 503K, and finished at about 873K. The apparent activation energy of Kissinger method was about 122.77kJ.mol^-1, the reaction orderwas 1.67, the frequency factor was 7.81×10^9, and therefore the dinetic epuation was dδ/dt=A·exp（- E/RT）·（1-δ）^n=7.81×10^9, exp（-122770/RT）·（l-δ）^1.67 . Coats-Redfem integral method was used to analyze the DTA curves of the samples at different heating rates, and the calculated apparent activation energy and frequency factor were 112. 13kJ· mol^-1 and 1.18 × 10^9, respectively, rather close to that of Kissinger method. X-ray diffraction （XRD） and scanning electron microscope （SEM） results shown that the synthesized LiMn2O3 possesses pure phase, regular shape and normal particle distribution.
文摘The chemical compositions of the sludge after treatment are tested by fully chemical analysis techniques. Its crystalline phase structure changes of the sludge calcined at different temperature are characterized by XRD method. Nitrogen gas isothermal adsorption method （77 K） is applied to measure the influences of ammonium bicarbonate on specific surface area and pore structure of activated alumina synthesized from waste aluminum sludge. The result shows that the amount of Al2O3 in the sludge accounts for more than 94%, and Na2Owt% in a 0.1-0.2% range. By calcining raw sludge at 600℃, monophase γ-Al2O3 is obtained. And this can satisfy the performance requirements of activated alumina adsorbent. The specific surface area of the specimen with NH4HCO3 added has expanded from 179 to 249 m^2/g and the pore volume from 0.25 to 1.11 cm^3/g as well as the average pore diameter from 5.6 to 17.8 nm. All these show that NH4HCO3 is an effective pore-expansion agent to remarkably improve the structure and performance of activated alumina synthesized from waste aluminum sludge.
