In this work,Fe_3Si–Si_3N_4–Al_2O_3 composites were prepared at 1300°C in an N_2 atmosphere using fused corundum and tabular alumina particles,Al_2O_3 fine powder,and ferrosilicon nitride(Fe_3Si–Si_3N_4) as ra...In this work,Fe_3Si–Si_3N_4–Al_2O_3 composites were prepared at 1300°C in an N_2 atmosphere using fused corundum and tabular alumina particles,Al_2O_3 fine powder,and ferrosilicon nitride(Fe_3Si–Si_3N_4) as raw materials and thermosetting phenolic resin as a binder.The effect of ferrosilicon nitride with different concentrations(0wt%,5wt%,10wt%,15wt%,20wt%,and 25wt%) on the properties of Fe_3Si–Si_3N_4–Al_2O_3 composites was investigated.The results show that the apparent porosity varies between 10.3% and 17.3%,the bulk density varies from 2.94 g/cm^3 and 3.30 g/cm^3,and the cold crushing strength ranges from 67 MPa to 93 MPa.Under the experimental conditions,ferrosilicon nitride,whose content decreases substantially,is unstable;part of the ferrosilicon nitride is converted into Fe_2C,whereas the remainder is retained,eventually forming the ferrosilicon alloy.Thermodynamic assessment of the Si_5AlON_7 indicated that the ferrosilicon alloy accelerated the reactions between Si_3N_4 and α-Al_2O_3 fine powder and that Si in the ferrosilicon alloy was nitrided directly,forming β-Si Al ON simultaneously.In addition,fused corundum did not react directly with Si_3N_4 because of its low reactivity.展开更多
Objective: To investigate the distributions of human leukocyte antigen (HLA)-A and-B alleles and HLA-A-B haplotypes in the Yi ethnic minority of the Yunnan Province, situated in southwestern China. Methods: DNA typing...Objective: To investigate the distributions of human leukocyte antigen (HLA)-A and-B alleles and HLA-A-B haplotypes in the Yi ethnic minority of the Yunnan Province, situated in southwestern China. Methods: DNA typing for HLA-A and-B loci was performed using the polymerase chain reaction-sequence-based typing (PCR-SBT) method on 114 randomly selected healthy individuals of the Yi population. The allelic frequencies of HLA-A and-B loci were calculated by direct counting and HLA-A-B haplotypes were estimated using the expectation maximization algorithm. Results: A total of 17 HLA-A and 38 HLA-B alleles were found in the Yi population. The most frequent alleles were A2402 (32.46%), A1101 (26.32%), and A0203 (10.09%) at the HLA-A locus and B4601 (12.28%), B1525 (10.09%), B4001 (8.77%), and B3802 (7.89%) at the HLA-B locus. The predominant HLA-A-B haplotypes were A2402-B1525 (7.86%) and A0203-B3802 (5.64%), followed by A1101-B4001 (4.69%). Phylogenetic analysis indicates that the Yi population in the Honghe, Yunnan Province of China basically belongs to groups of southeastern Asian origin, but shares some characteristics with northeastern Asian groups. Conclusion: The present study may add to the understanding of HLA polymorphism in the Yi ethnic group that was poorly defined previously, and provide useful information for bone marrow transplantation, anthropological research, and forensic sciences as well as for disease-association studies.展开更多
We studied the allelic frequency distributions and statistical forensic parameters of 21 new short tandem repeat(STR)loci and the amelogenin locus,which are not included in the combined DNA index system(CODIS),in a Ru...We studied the allelic frequency distributions and statistical forensic parameters of 21 new short tandem repeat(STR)loci and the amelogenin locus,which are not included in the combined DNA index system(CODIS),in a Russian ethnic minority group from the Inner Mongolia Autonomous Region,China.A total of 114 bloodstain samples from unrelated individuals were extracted and co-amplified with four fluorescence-labeled primers in a multiplex polymerase chain reaction(PCR)system.Using capillary electrophoresis,the PCR products of the 21 STR loci were separated and genotyped.A total of 161 alleles were observed in the Russian ethnic minority group,and corresponding allelic frequencies ranged from 0.0044 to 0.5965.The 21 non-CODIS STR loci of the Russian ethnic minority group were characterized by high genetic diversity and therefore may be useful for elucidating the population's genetic background,for individual identification,and for paternity testing in forensic practice.展开更多
文摘In this work,Fe_3Si–Si_3N_4–Al_2O_3 composites were prepared at 1300°C in an N_2 atmosphere using fused corundum and tabular alumina particles,Al_2O_3 fine powder,and ferrosilicon nitride(Fe_3Si–Si_3N_4) as raw materials and thermosetting phenolic resin as a binder.The effect of ferrosilicon nitride with different concentrations(0wt%,5wt%,10wt%,15wt%,20wt%,and 25wt%) on the properties of Fe_3Si–Si_3N_4–Al_2O_3 composites was investigated.The results show that the apparent porosity varies between 10.3% and 17.3%,the bulk density varies from 2.94 g/cm^3 and 3.30 g/cm^3,and the cold crushing strength ranges from 67 MPa to 93 MPa.Under the experimental conditions,ferrosilicon nitride,whose content decreases substantially,is unstable;part of the ferrosilicon nitride is converted into Fe_2C,whereas the remainder is retained,eventually forming the ferrosilicon alloy.Thermodynamic assessment of the Si_5AlON_7 indicated that the ferrosilicon alloy accelerated the reactions between Si_3N_4 and α-Al_2O_3 fine powder and that Si in the ferrosilicon alloy was nitrided directly,forming β-Si Al ON simultaneously.In addition,fused corundum did not react directly with Si_3N_4 because of its low reactivity.
基金Project supported by the National Natural Science Foundation of China (Nos. 30700470 and 30871348)the Shaan’xi Provincial Science and Technology Research and Development Project Fund (No. 2008K09-02), China
文摘Objective: To investigate the distributions of human leukocyte antigen (HLA)-A and-B alleles and HLA-A-B haplotypes in the Yi ethnic minority of the Yunnan Province, situated in southwestern China. Methods: DNA typing for HLA-A and-B loci was performed using the polymerase chain reaction-sequence-based typing (PCR-SBT) method on 114 randomly selected healthy individuals of the Yi population. The allelic frequencies of HLA-A and-B loci were calculated by direct counting and HLA-A-B haplotypes were estimated using the expectation maximization algorithm. Results: A total of 17 HLA-A and 38 HLA-B alleles were found in the Yi population. The most frequent alleles were A2402 (32.46%), A1101 (26.32%), and A0203 (10.09%) at the HLA-A locus and B4601 (12.28%), B1525 (10.09%), B4001 (8.77%), and B3802 (7.89%) at the HLA-B locus. The predominant HLA-A-B haplotypes were A2402-B1525 (7.86%) and A0203-B3802 (5.64%), followed by A1101-B4001 (4.69%). Phylogenetic analysis indicates that the Yi population in the Honghe, Yunnan Province of China basically belongs to groups of southeastern Asian origin, but shares some characteristics with northeastern Asian groups. Conclusion: The present study may add to the understanding of HLA polymorphism in the Yi ethnic group that was poorly defined previously, and provide useful information for bone marrow transplantation, anthropological research, and forensic sciences as well as for disease-association studies.
基金Project supported by the Program for New Century Excellent Talents of the Ministry of Education,China (No. NECT-10-0687)the Fun-damental Research Funds for the Central University (No. 2011jdgz20)the Shaanxi Provincial Science and Technology Research and Development Project Fund (No. 2012K16-08-01),China
文摘We studied the allelic frequency distributions and statistical forensic parameters of 21 new short tandem repeat(STR)loci and the amelogenin locus,which are not included in the combined DNA index system(CODIS),in a Russian ethnic minority group from the Inner Mongolia Autonomous Region,China.A total of 114 bloodstain samples from unrelated individuals were extracted and co-amplified with four fluorescence-labeled primers in a multiplex polymerase chain reaction(PCR)system.Using capillary electrophoresis,the PCR products of the 21 STR loci were separated and genotyped.A total of 161 alleles were observed in the Russian ethnic minority group,and corresponding allelic frequencies ranged from 0.0044 to 0.5965.The 21 non-CODIS STR loci of the Russian ethnic minority group were characterized by high genetic diversity and therefore may be useful for elucidating the population's genetic background,for individual identification,and for paternity testing in forensic practice.
