Foot-and-mouth disease (FMD) is an infectious and sometimes fatal viral disease that affects cloven-hoofed animals, and Chinese government adopts compulsory immunization measures for FMD. The adverse effects of FMD va...Foot-and-mouth disease (FMD) is an infectious and sometimes fatal viral disease that affects cloven-hoofed animals, and Chinese government adopts compulsory immunization measures for FMD. The adverse effects of FMD vaccine to pigs, cattle and goats have been reported increasingly frequent during the spring and autumn seasons when large numbers of farm livestock are vaccinated. The financial losses caused by vaccine adverse effects have been a serious concern for both farmers and primary prevention personnel. There are various causative factors reported to involve into adverse effect of FMD vaccine, including the inappropriate vaccine production, transportation and storage, livestock poor tolerance, and unqualified vaccinating manipulations. Symptomatic treatment and early drug prevention have a certain effect on the adverse effects. To analyze causes and propose countermeasures, in the current study possible reasons during the production and processing procedures of inactivated FMD vaccine were reviewed and corresponding countermeasures were recommended. The review may provide references for better use of vaccine to prevent FMD.展开更多
Microstructure performance in the welding zone of T91 heat-resistant steel under the condition of TIG welding was researched by means of metallography, X-ray diffraction and scanning electron microscope (SEM). Experim...Microstructure performance in the welding zone of T91 heat-resistant steel under the condition of TIG welding was researched by means of metallography, X-ray diffraction and scanning electron microscope (SEM). Experimental results indicated that microstructure of T91 weld metal was austenite + a little amount of S ferrite when using TGS-9cb filler wire. Substructure inside the austenite grain was crypto-crystal lath martensite, on which some Cr23C6 blocky carbides were distributed. The maximum hardness (HRC44) in the welding zone is near the fusion zone. There existed no obvious softening zone in the heat-affected zone (HAZ). For T91 steel tube of $63 mmx5 mm, when increasing welding heat input (E) from 4.8 kJ/cm to 12 5 kJ/cm, fracture morphology in the fusion zone and the HAZ changed from dimple fracture into quasi-cleavage fracture (QC). Controlling the welding heat input of about 9.8 kJ/cm is suitable in the welding of T91 heat-resistant steel.展开更多
Gene expression labeling and conditional manipulation of gene function are important for elaborate dissection of gene function.However,contemporary generation of pairwise dual-function knockin alleles to achieve both ...Gene expression labeling and conditional manipulation of gene function are important for elaborate dissection of gene function.However,contemporary generation of pairwise dual-function knockin alleles to achieve both conditional and geno-tagging effects with a single donor has not been reported.Here we first developed a strategy based on a flipping donor named FoRe to generate conditional knockout alleles coupled with fluorescent allele-labeling through NHEJ-mediated unidirectional targeted insertion in zebrafish facilitated by the CRISPR/Cas system.We demonstrated the feasibility of this strategy at sox10 and isl1 loci,and successfully achieved Cre-induced conditional knockout of target gene function and simultaneous switch of the fluorescent reporter,allowing generation of genetic mosaics for lineage tracing.We then improved the donor design enabling efficient one-step bidirectional knockin to generate paired positive and negative conditional alleles,both tagged with two different fluorescent reporters.By introducing Cre recombinase,these alleles could be used to achieve both conditional knockout and conditional gene restoration in parallel;furthermore,differential fluorescent labeling of the positive and negative alleles enables simple,early and efficient realtime discrimination of individual live embryos bearing different genotypes prior to the emergence of morphologically visible phenotypes.We named our improved donor as Bi-FoRe and demonstrated its feasibility at the sox10 locus.Furthermore,we eliminated the undesirable bacterial backbone in the donor using minicircle DNA technology.Our system could easily be expanded for other applications or to other organisms,and coupling fluorescent labeling of gene expression and conditional manipulation of gene function will provide unique opportunities to fully reveal the power of emerging single-cell sequencing technologies.展开更多
The Al-Cu-Li alloy is welded by using laser beam welding,and the welding wire ER4043 is used as filler metal. The microstructure and mechanical property of welded joints are systematically investigated. Microstructure...The Al-Cu-Li alloy is welded by using laser beam welding,and the welding wire ER4043 is used as filler metal. The microstructure and mechanical property of welded joints are systematically investigated. Microstructure analyses show that the fusion zone is mainly composed of α-Al matrix phase and some strengthening phases including T,δ’,θ’,β’ and T1,etc. During welding,the weld formation and joint quality are obviously improved by the addition of Al-Si filler wire. The measurements of mechanical property indicate that,compared with that of the base metal(BM), the microhardness in the weld zone is decreased to a certain extent. Under the appropriate welding parameters,the tensile strength of welded joint reaches 369.4 MPa,which is 67.8% of that of the BM. There are many dimples on the joint fracture surface,and it mainly presents the fracture characteristic of dimple aggregation.展开更多
文摘The title compound 5 was synthesized in 45% yield by the reaction of compound 3 with a, a-bis (bromomethyl)-2, 2-bipyridine in CH3CN at 70℃ for 24 h.
文摘Foot-and-mouth disease (FMD) is an infectious and sometimes fatal viral disease that affects cloven-hoofed animals, and Chinese government adopts compulsory immunization measures for FMD. The adverse effects of FMD vaccine to pigs, cattle and goats have been reported increasingly frequent during the spring and autumn seasons when large numbers of farm livestock are vaccinated. The financial losses caused by vaccine adverse effects have been a serious concern for both farmers and primary prevention personnel. There are various causative factors reported to involve into adverse effect of FMD vaccine, including the inappropriate vaccine production, transportation and storage, livestock poor tolerance, and unqualified vaccinating manipulations. Symptomatic treatment and early drug prevention have a certain effect on the adverse effects. To analyze causes and propose countermeasures, in the current study possible reasons during the production and processing procedures of inactivated FMD vaccine were reviewed and corresponding countermeasures were recommended. The review may provide references for better use of vaccine to prevent FMD.
基金The work was supported by the Foundation of National Key Laboratory of Advanced Welding Production Technology, Harbin Institute of Technology, China.
文摘Microstructure performance in the welding zone of T91 heat-resistant steel under the condition of TIG welding was researched by means of metallography, X-ray diffraction and scanning electron microscope (SEM). Experimental results indicated that microstructure of T91 weld metal was austenite + a little amount of S ferrite when using TGS-9cb filler wire. Substructure inside the austenite grain was crypto-crystal lath martensite, on which some Cr23C6 blocky carbides were distributed. The maximum hardness (HRC44) in the welding zone is near the fusion zone. There existed no obvious softening zone in the heat-affected zone (HAZ). For T91 steel tube of $63 mmx5 mm, when increasing welding heat input (E) from 4.8 kJ/cm to 12 5 kJ/cm, fracture morphology in the fusion zone and the HAZ changed from dimple fracture into quasi-cleavage fracture (QC). Controlling the welding heat input of about 9.8 kJ/cm is suitable in the welding of T91 heat-resistant steel.
基金This work was partially supported by grants from the National Key Research and Development Program of China(2019YFA0802800,2018YFA0801000,2016YFA0100500)the National Natural Science Foundation of China(NSFC)(Grant Nos.81770376,31871458,31671500 and 81371264)and the PKU Qidong-SLS Innovation Fund.
文摘Gene expression labeling and conditional manipulation of gene function are important for elaborate dissection of gene function.However,contemporary generation of pairwise dual-function knockin alleles to achieve both conditional and geno-tagging effects with a single donor has not been reported.Here we first developed a strategy based on a flipping donor named FoRe to generate conditional knockout alleles coupled with fluorescent allele-labeling through NHEJ-mediated unidirectional targeted insertion in zebrafish facilitated by the CRISPR/Cas system.We demonstrated the feasibility of this strategy at sox10 and isl1 loci,and successfully achieved Cre-induced conditional knockout of target gene function and simultaneous switch of the fluorescent reporter,allowing generation of genetic mosaics for lineage tracing.We then improved the donor design enabling efficient one-step bidirectional knockin to generate paired positive and negative conditional alleles,both tagged with two different fluorescent reporters.By introducing Cre recombinase,these alleles could be used to achieve both conditional knockout and conditional gene restoration in parallel;furthermore,differential fluorescent labeling of the positive and negative alleles enables simple,early and efficient realtime discrimination of individual live embryos bearing different genotypes prior to the emergence of morphologically visible phenotypes.We named our improved donor as Bi-FoRe and demonstrated its feasibility at the sox10 locus.Furthermore,we eliminated the undesirable bacterial backbone in the donor using minicircle DNA technology.Our system could easily be expanded for other applications or to other organisms,and coupling fluorescent labeling of gene expression and conditional manipulation of gene function will provide unique opportunities to fully reveal the power of emerging single-cell sequencing technologies.
基金supported by the Key Research and Development Program of Zhenjiang City(No. GY2019004).
文摘The Al-Cu-Li alloy is welded by using laser beam welding,and the welding wire ER4043 is used as filler metal. The microstructure and mechanical property of welded joints are systematically investigated. Microstructure analyses show that the fusion zone is mainly composed of α-Al matrix phase and some strengthening phases including T,δ’,θ’,β’ and T1,etc. During welding,the weld formation and joint quality are obviously improved by the addition of Al-Si filler wire. The measurements of mechanical property indicate that,compared with that of the base metal(BM), the microhardness in the weld zone is decreased to a certain extent. Under the appropriate welding parameters,the tensile strength of welded joint reaches 369.4 MPa,which is 67.8% of that of the BM. There are many dimples on the joint fracture surface,and it mainly presents the fracture characteristic of dimple aggregation.
