To construct a pUCP18/lasR^antisense plasmid carrying the reversed gene and analyze its effect on the virulence of Pseudomonas aeruginosus, LasR gene was amplified from the genome of Pseudomonas aeruginosus by PCR and...To construct a pUCP18/lasR^antisense plasmid carrying the reversed gene and analyze its effect on the virulence of Pseudomonas aeruginosus, LasR gene was amplified from the genome of Pseudomonas aeruginosus by PCR and reversely recombined with plasmid pUCP18. The recombinant pUCP18/lasR^antisense was verified by enzyme digestion, PCR and sequencing. The biological effects of pUCP18/lasR^antisense were examined by using RT-PCR, NAD method and the assay of pyocyanin. Our results showed that the expected full length lasR fragment （721 bp） was extended from Pseudomonas aeruginosus gene with PCR. And it is consistent with LasR gene of Pseudomonas aeruginosa in GenBank （No. NC_002516）. The recombinant plasmid was successfully constructed and transferred into Pseudomonas aeruginosus. The antisense nucleic acid of LasR gene could reduce the virulence of Pseudomonas aeruginosus and might serve as a new target site for treatment purpose.展开更多
The recently synthesized first 4d transition-metal oxide-hydride LaSr3NiRuO4H4 with the unusual high H:O ratio surprisingly displays no magnetic order down to 1.8 K. This is in sharp contrast to the similar unusual lo...The recently synthesized first 4d transition-metal oxide-hydride LaSr3NiRuO4H4 with the unusual high H:O ratio surprisingly displays no magnetic order down to 1.8 K. This is in sharp contrast to the similar unusual low-valent Ni^+-Ru^2+ layered oxide LaSrNiRuO4 which has a rather high ferromagnetic(FM) ordering Curie temperature TC^250 K. Using density functional calculations with the aid of crystal field level diagrams and superexchange pictures, we find that the contrasting magnetism is due to the distinct spin-orbital states of the Ru^2+ions(in addition to the common Ni+S = 1/2 state but with a different orbital state): the Ru^2+S = 0 state in LaSr3NiRuO4H4, but the Ru^2+S= 1 state in LaSrNiRuO4. The Ru^2+S = 0 state has the(xy)^2(xz, yz)^4 occupation due to the RuH4O2 octahedral coordination, and then the nonmagnetic Ru2+ions dilute the S= 1/2 Ni^+ sublattice which consequently has a very weak antiferromagnetic superexchange and thus accounts for the presence of no magnetic order down to 1.8 K in LaSr3NiRuO4H4. In strong contrast, the Ru^2+S = 1 state in LaSrNiRuO4 has the(3z^2-r^2)^2(xz, yz)^3(xy)^1 occupation due to the planar square RuO4 coordination, and then the multi-orbital FM superexchange between the S= 1/2 Ni^+ and S= 1 Ru^2+ions gives rise to the high TC in LaSrNiRuO4. This work highlights the importance of spin-orbital states in determining the distinct magnetism.展开更多
LaSr2A1Os：Sm3＋ phosphors were synthesized by the Pechini-type sol-gel process. The X-ray diffraction pattern revealed that a pure LaSr2AIO5 phase was obtained with a sintering temperature of 1200 ℃. Microstructure ...LaSr2A1Os：Sm3＋ phosphors were synthesized by the Pechini-type sol-gel process. The X-ray diffraction pattern revealed that a pure LaSr2AIO5 phase was obtained with a sintering temperature of 1200 ℃. Microstructure characterization showed that the particles were spherical in shape with a mean size of 2.93 μm. Being a candidate orange/red emitting phosphor for orange and white light emitting diodes, LaSr2A1Os：Sm3＋ could be effectively excited by both near-ultraviolet （NUV） and blue lights with typical f-f transitions of Sm3＋ ions. The most intense emission corresponding to 4G5/2---＊6H7/2 （604 nm） could be achieved at the same Sm3＋ concentration of 4 mol.%. The chromaticity coordinates of La0.96Sr2A1Os：0.04Sm3. phosphor under the excitation of 407 and 458 nm were （0.57, 0.43） and （0.59, 0.38）, respectively. Further study was carried out using Van Uitert＇s and Dexter＇s models. A consistent result was obtained that electric dipole-dipole interaction was dominant for the energy transfer among Sm3＋ ions. The critical distance for energy transfer among Sm3＋ ions in LaSr2A105 was calculated to be ca. 1.843 nm.展开更多
LaSr2 Mn2 O7,a Ruddlesden-Popper type bilayered perovskite,was investigated as oxygen catalyst for oxygen reduction reaction(ORR) and active electrode material for electrochemical capacitors in KOH solutions.XPS resul...LaSr2 Mn2 O7,a Ruddlesden-Popper type bilayered perovskite,was investigated as oxygen catalyst for oxygen reduction reaction(ORR) and active electrode material for electrochemical capacitors in KOH solutions.XPS results show that Mn takes a mixed Mn2+,Mn3+and Mn4+valence state with an average valence of 3.4.As catalyst towards ORR,LaSr2 Mn2 O7 and LaSr2 Mn2 O7/acetylene black composite favor four electron pathways for ORR.LaSr2 Mn2 O7/C composite shows a comparable onset potential for ORR to that of Pt/C electrode.The improved ORR activity of LaSr2 Mn2 O7/acetylene black composite is attributed to the synergy between catalytic LaSr2 Mn2 O7 and conductive acetylene black.As electrode material for electrochemical capacitors,LaSr2 Mn2 O7 exhibits a maximum specific capacitance of 167.2 F/g with 62%faradic contribution at a scan rate of 1 mV/s in cyclic voltammetry test.展开更多
基金This project was supported by a grant from Wuhan Mu-nicipal Health Bureau (No 2005CB522901)
文摘To construct a pUCP18/lasR^antisense plasmid carrying the reversed gene and analyze its effect on the virulence of Pseudomonas aeruginosus, LasR gene was amplified from the genome of Pseudomonas aeruginosus by PCR and reversely recombined with plasmid pUCP18. The recombinant pUCP18/lasR^antisense was verified by enzyme digestion, PCR and sequencing. The biological effects of pUCP18/lasR^antisense were examined by using RT-PCR, NAD method and the assay of pyocyanin. Our results showed that the expected full length lasR fragment （721 bp） was extended from Pseudomonas aeruginosus gene with PCR. And it is consistent with LasR gene of Pseudomonas aeruginosa in GenBank （No. NC_002516）. The recombinant plasmid was successfully constructed and transferred into Pseudomonas aeruginosus. The antisense nucleic acid of LasR gene could reduce the virulence of Pseudomonas aeruginosus and might serve as a new target site for treatment purpose.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11674064 and 11474059the National Key Research and Development Program of China under Grant No 2016YFA0300700
文摘The recently synthesized first 4d transition-metal oxide-hydride LaSr3NiRuO4H4 with the unusual high H:O ratio surprisingly displays no magnetic order down to 1.8 K. This is in sharp contrast to the similar unusual low-valent Ni^+-Ru^2+ layered oxide LaSrNiRuO4 which has a rather high ferromagnetic(FM) ordering Curie temperature TC^250 K. Using density functional calculations with the aid of crystal field level diagrams and superexchange pictures, we find that the contrasting magnetism is due to the distinct spin-orbital states of the Ru^2+ions(in addition to the common Ni+S = 1/2 state but with a different orbital state): the Ru^2+S = 0 state in LaSr3NiRuO4H4, but the Ru^2+S= 1 state in LaSrNiRuO4. The Ru^2+S = 0 state has the(xy)^2(xz, yz)^4 occupation due to the RuH4O2 octahedral coordination, and then the nonmagnetic Ru2+ions dilute the S= 1/2 Ni^+ sublattice which consequently has a very weak antiferromagnetic superexchange and thus accounts for the presence of no magnetic order down to 1.8 K in LaSr3NiRuO4H4. In strong contrast, the Ru^2+S = 1 state in LaSrNiRuO4 has the(3z^2-r^2)^2(xz, yz)^3(xy)^1 occupation due to the planar square RuO4 coordination, and then the multi-orbital FM superexchange between the S= 1/2 Ni^+ and S= 1 Ru^2+ions gives rise to the high TC in LaSrNiRuO4. This work highlights the importance of spin-orbital states in determining the distinct magnetism.
基金supported by the Funding of Jiangsu Innovation Program for Graduate Education(CXZZ12_0147)funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘LaSr2A1Os：Sm3＋ phosphors were synthesized by the Pechini-type sol-gel process. The X-ray diffraction pattern revealed that a pure LaSr2AIO5 phase was obtained with a sintering temperature of 1200 ℃. Microstructure characterization showed that the particles were spherical in shape with a mean size of 2.93 μm. Being a candidate orange/red emitting phosphor for orange and white light emitting diodes, LaSr2A1Os：Sm3＋ could be effectively excited by both near-ultraviolet （NUV） and blue lights with typical f-f transitions of Sm3＋ ions. The most intense emission corresponding to 4G5/2---＊6H7/2 （604 nm） could be achieved at the same Sm3＋ concentration of 4 mol.%. The chromaticity coordinates of La0.96Sr2A1Os：0.04Sm3. phosphor under the excitation of 407 and 458 nm were （0.57, 0.43） and （0.59, 0.38）, respectively. Further study was carried out using Van Uitert＇s and Dexter＇s models. A consistent result was obtained that electric dipole-dipole interaction was dominant for the energy transfer among Sm3＋ ions. The critical distance for energy transfer among Sm3＋ ions in LaSr2A105 was calculated to be ca. 1.843 nm.
基金Project supported by National Natural Science Foundation of China (21571095,61366004)。
文摘LaSr2 Mn2 O7,a Ruddlesden-Popper type bilayered perovskite,was investigated as oxygen catalyst for oxygen reduction reaction(ORR) and active electrode material for electrochemical capacitors in KOH solutions.XPS results show that Mn takes a mixed Mn2+,Mn3+and Mn4+valence state with an average valence of 3.4.As catalyst towards ORR,LaSr2 Mn2 O7 and LaSr2 Mn2 O7/acetylene black composite favor four electron pathways for ORR.LaSr2 Mn2 O7/C composite shows a comparable onset potential for ORR to that of Pt/C electrode.The improved ORR activity of LaSr2 Mn2 O7/acetylene black composite is attributed to the synergy between catalytic LaSr2 Mn2 O7 and conductive acetylene black.As electrode material for electrochemical capacitors,LaSr2 Mn2 O7 exhibits a maximum specific capacitance of 167.2 F/g with 62%faradic contribution at a scan rate of 1 mV/s in cyclic voltammetry test.
