The phylogenetic diversity of cuhurable psychrophilic bacteria associated with sea ice from the high latitude regions of Canadian Basin and Chukchi Sea, Arctic, was investigated. A total of 34 psychropilic strains wer...The phylogenetic diversity of cuhurable psychrophilic bacteria associated with sea ice from the high latitude regions of Canadian Basin and Chukchi Sea, Arctic, was investigated. A total of 34 psychropilic strains were isolated using three methods of （ Ⅰ ） dilution plating （ at 4 ℃ ）, （ Ⅱ ） bath culturing （ at - 1 ℃ ） and dilution plating, and （ Ⅲ） cold shock （ -20 ℃ for 24 h）, bath culturing and dilution plating under aerobic conditions. Sea-ice samples were exposed to -20 ℃ for 24 h that might reduce the number of common microorganisms and encourage outgrowth of psyehrophilic strains. This process might be able to be introduced to isolation psychrophilic bacteria from other environmental samples in future study. 16S rDNA nearly full-length sequence analysis revealed that psychrophilic strains felled in two phylo- genetic divisions, γ-proteobacteria （in the genera ColweUia,Marinobaeter、Shewanella,Glaciecola,Marinomortas and Pseudoalteromortas ） and Cytophaga-Flexibacter-Baeteroides （ Flavobacterlum and Psyehroflexus）. Fifteen of bacterial isolates quite likely represented novel species （16S rDNA sequence similarity below 98% ）. One of strains （BSi20002） from Canadian Basin showed 100% sequence similarity to that of Marinobacter sp. ANT8277 isolated from the Antarctic Weddell sea ice, suggesting bacteria may have a bipolar distribution at the species level.展开更多
A convenient and practicable method for the synthesis of the novel 2-（trifluoromethyl）-6-arylimidazo[2,1-b][1,3,4]-thiadiazole （bis-）Mannich base derivatives containing various substitutedpiperazine motif has been...A convenient and practicable method for the synthesis of the novel 2-（trifluoromethyl）-6-arylimidazo[2,1-b][1,3,4]-thiadiazole （bis-）Mannich base derivatives containing various substitutedpiperazine motif has been developed based on the fused-heterocycle intermediate. The new structures were identified through melting points, ^1H NMR, ^13C NMR, ^19F NMR, elemental analysis （or HRMS） and X-ray single-crystal diffraction. The pesticidal bioassays showed that some of compounds exhibited good fungicidal activities against Cercospora arachidicola, Physalospora piricola and Rhizoctonia cereali at 50 mg/L; some of them displayed favourable insecticidal activities against oriental armyworm （Mythimna separata Walker） at 200 rag/L, particularly, Vk and Vm with mortality rate of 75% and 80% respectively, could be considered as new insecticidal lead compounds for further structural optimization.展开更多
Cellulose diacetate(CDA)can be melt processed to produce numerous and widely-used plastic products.However,due to the high glass transition temperature(Tg)of CDA,the addition of up to 30 wt%of micromolecular plasticiz...Cellulose diacetate(CDA)can be melt processed to produce numerous and widely-used plastic products.However,due to the high glass transition temperature(Tg)of CDA,the addition of up to 30 wt%of micromolecular plasticizers is indispensable,which significantly reduces the dimensional stability and raises safety concerns from the migration of plasticizers.In this work,a series of CDA-graft poly(lactic acid)(CDA-g-PLA)copolymers were synthesized by ring-opening polymerization of lactide onto the hydroxyI groups of CDA.The resultant CDA-g-PLA copolymers possess adjustable degrees of substitution(DSpua)and side chain length(DPpLa)by controlling the reaction time and feed ratio.The Tgs and thermal flow temperatures(Ts)of CDA-g-PLA strongly depend on DPpA such as the Tgs decrease linearly with the increase of DPA.The CDA-g-PLA copolymers with the DPLA of 3-9 can be directly processed to transparent plastics by melt processing without any external plasticizers,because of their low Tfs of 170-215℃.More impressively.the CDA-g PLA can act as the macromolecular plasticizer.The obtained CDA/CDA-g-PLA has higher storage modulus,flexural modulus and Young's modulus than the commercial CDA plasticized with triethyl citrate.In addition,the CDA/CDA-g PLA exhibits high dimensional stabilty and anti-migration property.During a long term treatment at 80℃ and 60%humidity,the CDA/CDA-g-PLA can retain the initial shape.Therefore,this work not only proposes a facile method for achieving a direct thermoplastic processing of CDA,but also provides a macromolecular plasticizer for CDA to make lightweight,stable and safer biobased thermoplastics.展开更多
文摘The phylogenetic diversity of cuhurable psychrophilic bacteria associated with sea ice from the high latitude regions of Canadian Basin and Chukchi Sea, Arctic, was investigated. A total of 34 psychropilic strains were isolated using three methods of （ Ⅰ ） dilution plating （ at 4 ℃ ）, （ Ⅱ ） bath culturing （ at - 1 ℃ ） and dilution plating, and （ Ⅲ） cold shock （ -20 ℃ for 24 h）, bath culturing and dilution plating under aerobic conditions. Sea-ice samples were exposed to -20 ℃ for 24 h that might reduce the number of common microorganisms and encourage outgrowth of psyehrophilic strains. This process might be able to be introduced to isolation psychrophilic bacteria from other environmental samples in future study. 16S rDNA nearly full-length sequence analysis revealed that psychrophilic strains felled in two phylo- genetic divisions, γ-proteobacteria （in the genera ColweUia,Marinobaeter、Shewanella,Glaciecola,Marinomortas and Pseudoalteromortas ） and Cytophaga-Flexibacter-Baeteroides （ Flavobacterlum and Psyehroflexus）. Fifteen of bacterial isolates quite likely represented novel species （16S rDNA sequence similarity below 98% ）. One of strains （BSi20002） from Canadian Basin showed 100% sequence similarity to that of Marinobacter sp. ANT8277 isolated from the Antarctic Weddell sea ice, suggesting bacteria may have a bipolar distribution at the species level.
基金This work was supported by the National Key Research and Development Program of China （No. 2017YFD0200505）, the National Natural Science Foundation of China （Nos. 21372133 and 21772103）, and Tianjin Natural Science Foundation （No. 17JCYBJC19900）. We thank the teachers of the Biological Assay Center, Nankai University, for kind bioassay assistance of compounds.
文摘A convenient and practicable method for the synthesis of the novel 2-（trifluoromethyl）-6-arylimidazo[2,1-b][1,3,4]-thiadiazole （bis-）Mannich base derivatives containing various substitutedpiperazine motif has been developed based on the fused-heterocycle intermediate. The new structures were identified through melting points, ^1H NMR, ^13C NMR, ^19F NMR, elemental analysis （or HRMS） and X-ray single-crystal diffraction. The pesticidal bioassays showed that some of compounds exhibited good fungicidal activities against Cercospora arachidicola, Physalospora piricola and Rhizoctonia cereali at 50 mg/L; some of them displayed favourable insecticidal activities against oriental armyworm （Mythimna separata Walker） at 200 rag/L, particularly, Vk and Vm with mortality rate of 75% and 80% respectively, could be considered as new insecticidal lead compounds for further structural optimization.
基金This work was finacially supported by the National Key Research and Development Program of China(No.2017YFA0403103)the Key Programs of the Chinese Academy of Sciences(No.ZDRW-CN-2018-2)the Youth Innovation Promotion Association CAS(No.2018040).
文摘Cellulose diacetate(CDA)can be melt processed to produce numerous and widely-used plastic products.However,due to the high glass transition temperature(Tg)of CDA,the addition of up to 30 wt%of micromolecular plasticizers is indispensable,which significantly reduces the dimensional stability and raises safety concerns from the migration of plasticizers.In this work,a series of CDA-graft poly(lactic acid)(CDA-g-PLA)copolymers were synthesized by ring-opening polymerization of lactide onto the hydroxyI groups of CDA.The resultant CDA-g-PLA copolymers possess adjustable degrees of substitution(DSpua)and side chain length(DPpLa)by controlling the reaction time and feed ratio.The Tgs and thermal flow temperatures(Ts)of CDA-g-PLA strongly depend on DPpA such as the Tgs decrease linearly with the increase of DPA.The CDA-g-PLA copolymers with the DPLA of 3-9 can be directly processed to transparent plastics by melt processing without any external plasticizers,because of their low Tfs of 170-215℃.More impressively.the CDA-g PLA can act as the macromolecular plasticizer.The obtained CDA/CDA-g-PLA has higher storage modulus,flexural modulus and Young's modulus than the commercial CDA plasticized with triethyl citrate.In addition,the CDA/CDA-g PLA exhibits high dimensional stabilty and anti-migration property.During a long term treatment at 80℃ and 60%humidity,the CDA/CDA-g-PLA can retain the initial shape.Therefore,this work not only proposes a facile method for achieving a direct thermoplastic processing of CDA,but also provides a macromolecular plasticizer for CDA to make lightweight,stable and safer biobased thermoplastics.
