Because of its high purity and excellent orientation, mesophase pitch is a superior precursor for high-performance car-bon materials. However, the preparation of top-notch mesophase pitch faces challenges. Catalytic p...Because of its high purity and excellent orientation, mesophase pitch is a superior precursor for high-performance car-bon materials. However, the preparation of top-notch mesophase pitch faces challenges. Catalytic polycondensation at low temperat-ures is more favorable for synthesizing mesophase pitch, because it circumvents the high-temperature free radical reaction of other thermal polycondensation approaches. The reaction is gentle and can be easily controlled. It has the potential to significantly im-prove the yield of mesophase pitch and easily introduce naphthenic characteristics into the molecules, catalytic polycondensation is therefore a preferred method of synthesizing highly spinnable mesophase pitch. This review provides a synopsis of the selective pre-treatment of the raw materials to prepare different mesophase pitches, and explains the reaction mechanism and associated research advances for different catalytic systems in recent years. Finally, how to manufacture high-quality mesophase pitch by using a cata-lyst-promoter system is summarized and proposed, which may provide a theoretical basis for the future design of high-quality pitch molecules.展开更多
Objective: Allelic polymorphisms of CCR5△32CCR2b-64I,CX3CR1-2491280M and SDF1-3'A associatedwith HIV-1 infection and disease progression wereinvestigated in indigenous Uygur populations from theXinjiang Uygur Aut...Objective: Allelic polymorphisms of CCR5△32CCR2b-64I,CX3CR1-2491280M and SDF1-3'A associatedwith HIV-1 infection and disease progression wereinvestigated in indigenous Uygur populations from theXinjiang Uygur Autonomous Region of China. Methods: The study population comprised 316 healthyUygur subjects with an age range of 1-80 years old, fromwhom whole peripheral blood samples were collected andnone were HIV-1 seropositive. Genomic DNA samples werepurified using a Qiagen Blood Kit. Genotyping of theaforementioned four alleles was performed using PCR orPCR/RFLP assay, and further confirmed by direct DNAsequencing. Results: The allelic frequencies in Chinese Uygurpopulation were as follows: 3.48% for CCR5△32; 19.45% forCCR2b-64I; 13.8% for CX3CR1-2491280M haplotype, and20.41% for SDF1-3'A. Mutant allele distributions amongUygur populations were in accordance with theHardy-Weinberg equilibrium. No statistical difference wasfound between the frequency of the three HIV coreceptors andtheir respective ligand genes. Conclusion: The frequency of SDF1-3'A andCX3CR1-2491280M haplotypes in these Uygur populationswas similar to that of Caucasian people, while the frequency ofthe CCR2b-64I haplotype more closely matched the HanChinese. The frequency of CCR5△A32 in Uygur populationswas between Caucasian and Hall frequencies, the more closelymatching the frequency in Medi-Asia people. No geneticlinkage between any two of the three HIV coreceptor geneswas found, but obvious genetic linkages existed betweenCX3CR1-249I and CX3CR1-280M,with even higher linkagedegrees than Caucasian people.展开更多
This paper aims to examine the specific ways in which China＇s exports of manufactured goods to the United States boost the U.S. job market. Using the OECD STAN Bilateral Trade Database by Industry and End-use Categor...This paper aims to examine the specific ways in which China＇s exports of manufactured goods to the United States boost the U.S. job market. Using the OECD STAN Bilateral Trade Database by Industry and End-use Category to calculate the share of U.S. intermediate products used in the manufactured goods China exports to the U.S., this paper finds that the ＂U.S. content＂ in China＇s exports of manufactured goods to the U.S. increases with the technology content of the goods and shows a decreasing trend over time. From 2006 to 2010, the average ＂US. content＂ in China＇s exports of manufactured goods to the U.S. was 1%, and such content in China＇s exports of high-end manufactured goods was 1.6%. On this basis and using the employment-output ratio in the U.S. Employment Demand Matrix, this paper concludes that as many as 1.71 million jobs have been created by the U.S. intermediate products used in China＇s exports of manufactured goods to the U.S. during the same period. Thus, the development of Sino-U.S. trade has a positive impact on the job market in the U.S.. By contrast, instead of improving the employment situation in the U.S., the RMB appreciation proposed by the U.S. might even have a negative effect.展开更多
文摘Because of its high purity and excellent orientation, mesophase pitch is a superior precursor for high-performance car-bon materials. However, the preparation of top-notch mesophase pitch faces challenges. Catalytic polycondensation at low temperat-ures is more favorable for synthesizing mesophase pitch, because it circumvents the high-temperature free radical reaction of other thermal polycondensation approaches. The reaction is gentle and can be easily controlled. It has the potential to significantly im-prove the yield of mesophase pitch and easily introduce naphthenic characteristics into the molecules, catalytic polycondensation is therefore a preferred method of synthesizing highly spinnable mesophase pitch. This review provides a synopsis of the selective pre-treatment of the raw materials to prepare different mesophase pitches, and explains the reaction mechanism and associated research advances for different catalytic systems in recent years. Finally, how to manufacture high-quality mesophase pitch by using a cata-lyst-promoter system is summarized and proposed, which may provide a theoretical basis for the future design of high-quality pitch molecules.
基金This project was funded by the National Natural Science Foundation of China(No:397706830)
文摘Objective: Allelic polymorphisms of CCR5△32CCR2b-64I,CX3CR1-2491280M and SDF1-3'A associatedwith HIV-1 infection and disease progression wereinvestigated in indigenous Uygur populations from theXinjiang Uygur Autonomous Region of China. Methods: The study population comprised 316 healthyUygur subjects with an age range of 1-80 years old, fromwhom whole peripheral blood samples were collected andnone were HIV-1 seropositive. Genomic DNA samples werepurified using a Qiagen Blood Kit. Genotyping of theaforementioned four alleles was performed using PCR orPCR/RFLP assay, and further confirmed by direct DNAsequencing. Results: The allelic frequencies in Chinese Uygurpopulation were as follows: 3.48% for CCR5△32; 19.45% forCCR2b-64I; 13.8% for CX3CR1-2491280M haplotype, and20.41% for SDF1-3'A. Mutant allele distributions amongUygur populations were in accordance with theHardy-Weinberg equilibrium. No statistical difference wasfound between the frequency of the three HIV coreceptors andtheir respective ligand genes. Conclusion: The frequency of SDF1-3'A andCX3CR1-2491280M haplotypes in these Uygur populationswas similar to that of Caucasian people, while the frequency ofthe CCR2b-64I haplotype more closely matched the HanChinese. The frequency of CCR5△A32 in Uygur populationswas between Caucasian and Hall frequencies, the more closelymatching the frequency in Medi-Asia people. No geneticlinkage between any two of the three HIV coreceptor geneswas found, but obvious genetic linkages existed betweenCX3CR1-249I and CX3CR1-280M,with even higher linkagedegrees than Caucasian people.
基金supported by the Fundamental Research Funds for the Central Universitiesthe Research Funds of Renmin University of China(Grant No.13XNI006)
文摘This paper aims to examine the specific ways in which China＇s exports of manufactured goods to the United States boost the U.S. job market. Using the OECD STAN Bilateral Trade Database by Industry and End-use Category to calculate the share of U.S. intermediate products used in the manufactured goods China exports to the U.S., this paper finds that the ＂U.S. content＂ in China＇s exports of manufactured goods to the U.S. increases with the technology content of the goods and shows a decreasing trend over time. From 2006 to 2010, the average ＂US. content＂ in China＇s exports of manufactured goods to the U.S. was 1%, and such content in China＇s exports of high-end manufactured goods was 1.6%. On this basis and using the employment-output ratio in the U.S. Employment Demand Matrix, this paper concludes that as many as 1.71 million jobs have been created by the U.S. intermediate products used in China＇s exports of manufactured goods to the U.S. during the same period. Thus, the development of Sino-U.S. trade has a positive impact on the job market in the U.S.. By contrast, instead of improving the employment situation in the U.S., the RMB appreciation proposed by the U.S. might even have a negative effect.
