Gold(Au) nanostructures(NSs) have been widely employed as cocatalysts to improve the photoactivity of semiconductor materials, while a systematic summary of the engineering approaches of Au NSs to maximize the solar-t...Gold(Au) nanostructures(NSs) have been widely employed as cocatalysts to improve the photoactivity of semiconductor materials, while a systematic summary of the engineering approaches of Au NSs to maximize the solar-to-fuel conversion efficiency is still lacking. In this review, the recently developed strategies for elevating the overall photocatalytic performance of Au-based catalysts and the deep physical chemistry mechanisms are highlighted. Firstly, the synthetic approaches of Au NSs are summarized, followed by an elaboration on their multiple functions in improving photoactivity. Afterward, modification strategies of Au NSs used to enhance the photocatalytic efficiency of Au-semiconductor composites,including controlling the Au NSs morphology, size, crystal phase, defect engineering, alloying with different metals, modulating interfacial interaction, and introducing an external field, are summarized and discussed independently. Additionally, advanced characterization techniques that can provide insights into the charge dynamics of the photocatalysts are introduced. Finally, we share our opinion on the challenges and outline potentially promising opportunities and directions for efficient Au-based photocatalysis research moving forward. We sincerely look forward to this review can deliver insightful views to design efficient Au-based photocatalysts and spur certain innovations to other metal-based catalysts.展开更多
Azalomycin F<sub>5a</sub>, a 36-membered macrocyclic lactone isolated from several streptomyces strains, presented remarkable anti-methicillin-resistant Staphylococcus aureus (MRSA) activities. To improve ...Azalomycin F<sub>5a</sub>, a 36-membered macrocyclic lactone isolated from several streptomyces strains, presented remarkable anti-methicillin-resistant Staphylococcus aureus (MRSA) activities. To improve its anti-MRSA potential and to evaluate the probability of MRSA resistant to it before development, the anti-MRSA activities of azalomycin F<sub>5a</sub> in combination with vitamin K<sub>3</sub> were first evaluated using checkerboard assay. Then the minimal concentration inhibiting colony formation by 99% (MIC<sub>99</sub>) and mutant prevention concentration (MPC) of azalomycin F<sub>5a</sub> alone and in combination with vitamin K<sub>3</sub> against MRSA were determined using agar plates with linear antimicrobial concentration decrease. The fractional inhibitory concentration indexes (FICIs) of 0.25 - 0.50 showed the synergistic activity of azalomycin F<sub>5a</sub> in combination with vitamin K<sub>3</sub>. The mutant selection windows (MSWs, MIC<sub>99</sub>-MPC) of azalomycin F<sub>5a</sub> alone against MRSA tested were 2.07 - 6.40 μg/mL, and the MPCs of azalomycin F<sub>5a</sub> in combination with vitamin K<sub>3</sub> against MRSA tested were 1.60 - 3.20 μg/mL. These indicated that the MPCs of azalomycin F<sub>5a</sub> in combination could drop down to below its MIC<sub>99</sub> alone. According to the hypothesis of MSW, the narrower MSWs of azalomycin F<sub>5a </sub>alone, even closed MSWs in combination with vitamin K<sub>3</sub>, together with their synergistic anti-MRSA activities, indicated that azalomycin F<sub>5a </sub>had a good potential to develop as a new antimicrobial agent.展开更多
Streptomyces sp. ZZ035 isolated from a folk medicinal soil sample in China showed remarkable antimicrobial activities. During the isolation of secondary metabolites, a white crystal powder (1) was isolated from the br...Streptomyces sp. ZZ035 isolated from a folk medicinal soil sample in China showed remarkable antimicrobial activities. During the isolation of secondary metabolites, a white crystal powder (1) was isolated from the broth of this strain. Its nuclear magnetic resonance (NMR) and infrared (IR) spectra indicated that it was a complex composed of triglycerides. Next, six C15-17 long- chain fatty acids derived from these triglycerides were respectively identified as n-pentadecanoyl, 12-methyltetradecanoyl, 14-methyl pentadecanoyl, palmitoyl, 15-methyl hexadecanoyl and 14-methyl hexadecanoyl using the gas chromatography-mass spectroscopy (GC-MS) technology. Finally, the 13C and 1H assignments of 1 were achieved through the analyses of NMR data. Based on above, their detailed NMR spectroscopic elucidation and meticulous 13C, 1H assignments, especially the split peaks and coupling correlation of protons attached on the glycerol carbons, were performed for distinguishing triglycerides from other glycerides and for the identification of the long-chain fatty acids, and which would be helpful to the qualitative and quantitative analyses of tri-, di-and mono-glycerides.展开更多
This study focuses on analyzing aqueous solutions of aroma-active compounds in Xinhui Chenpi distilled after being heated with headspace solid-phase microextraction and gas chromatography-mass spectrometry(HS-SPME-GC/...This study focuses on analyzing aqueous solutions of aroma-active compounds in Xinhui Chenpi distilled after being heated with headspace solid-phase microextraction and gas chromatography-mass spectrometry(HS-SPME-GC/MS).Feasibility of this method was also tested by comparison with crushed samples.The study also analyzed the aqueous solutions of the aroma-active compounds employing gas chromatography-olfactometry(GC-O)defense,aroma extraction dilution analysis(AEDA)and odor activity value(OAV)as well as their emission patterns.According to the study,there are 24 major aroma-active detected in the aqueous solution.Linalool,d-limonene,2-methoxy-4-vinylphenol,andα-terpineol with sweet,spicy,and woody aroma contributed the most to the aroma-active compounds and were considered to be the essential aroma substances of Chenpi.When heated,the aroma of aromatic-active compounds rich in Chenpi volatilized rapidly and the release dropped dramatically in a short time.The substantial aroma-active compounds can be collected from the first ten released segments.展开更多
基金financially supported by the National Natural Science Foundation of China (21902132)the Research Foundation-Flanders (1280021N, 1242922N, 1298323N)。
文摘Gold(Au) nanostructures(NSs) have been widely employed as cocatalysts to improve the photoactivity of semiconductor materials, while a systematic summary of the engineering approaches of Au NSs to maximize the solar-to-fuel conversion efficiency is still lacking. In this review, the recently developed strategies for elevating the overall photocatalytic performance of Au-based catalysts and the deep physical chemistry mechanisms are highlighted. Firstly, the synthetic approaches of Au NSs are summarized, followed by an elaboration on their multiple functions in improving photoactivity. Afterward, modification strategies of Au NSs used to enhance the photocatalytic efficiency of Au-semiconductor composites,including controlling the Au NSs morphology, size, crystal phase, defect engineering, alloying with different metals, modulating interfacial interaction, and introducing an external field, are summarized and discussed independently. Additionally, advanced characterization techniques that can provide insights into the charge dynamics of the photocatalysts are introduced. Finally, we share our opinion on the challenges and outline potentially promising opportunities and directions for efficient Au-based photocatalysis research moving forward. We sincerely look forward to this review can deliver insightful views to design efficient Au-based photocatalysts and spur certain innovations to other metal-based catalysts.
文摘Azalomycin F<sub>5a</sub>, a 36-membered macrocyclic lactone isolated from several streptomyces strains, presented remarkable anti-methicillin-resistant Staphylococcus aureus (MRSA) activities. To improve its anti-MRSA potential and to evaluate the probability of MRSA resistant to it before development, the anti-MRSA activities of azalomycin F<sub>5a</sub> in combination with vitamin K<sub>3</sub> were first evaluated using checkerboard assay. Then the minimal concentration inhibiting colony formation by 99% (MIC<sub>99</sub>) and mutant prevention concentration (MPC) of azalomycin F<sub>5a</sub> alone and in combination with vitamin K<sub>3</sub> against MRSA were determined using agar plates with linear antimicrobial concentration decrease. The fractional inhibitory concentration indexes (FICIs) of 0.25 - 0.50 showed the synergistic activity of azalomycin F<sub>5a</sub> in combination with vitamin K<sub>3</sub>. The mutant selection windows (MSWs, MIC<sub>99</sub>-MPC) of azalomycin F<sub>5a</sub> alone against MRSA tested were 2.07 - 6.40 μg/mL, and the MPCs of azalomycin F<sub>5a</sub> in combination with vitamin K<sub>3</sub> against MRSA tested were 1.60 - 3.20 μg/mL. These indicated that the MPCs of azalomycin F<sub>5a</sub> in combination could drop down to below its MIC<sub>99</sub> alone. According to the hypothesis of MSW, the narrower MSWs of azalomycin F<sub>5a </sub>alone, even closed MSWs in combination with vitamin K<sub>3</sub>, together with their synergistic anti-MRSA activities, indicated that azalomycin F<sub>5a </sub>had a good potential to develop as a new antimicrobial agent.
文摘Streptomyces sp. ZZ035 isolated from a folk medicinal soil sample in China showed remarkable antimicrobial activities. During the isolation of secondary metabolites, a white crystal powder (1) was isolated from the broth of this strain. Its nuclear magnetic resonance (NMR) and infrared (IR) spectra indicated that it was a complex composed of triglycerides. Next, six C15-17 long- chain fatty acids derived from these triglycerides were respectively identified as n-pentadecanoyl, 12-methyltetradecanoyl, 14-methyl pentadecanoyl, palmitoyl, 15-methyl hexadecanoyl and 14-methyl hexadecanoyl using the gas chromatography-mass spectroscopy (GC-MS) technology. Finally, the 13C and 1H assignments of 1 were achieved through the analyses of NMR data. Based on above, their detailed NMR spectroscopic elucidation and meticulous 13C, 1H assignments, especially the split peaks and coupling correlation of protons attached on the glycerol carbons, were performed for distinguishing triglycerides from other glycerides and for the identification of the long-chain fatty acids, and which would be helpful to the qualitative and quantitative analyses of tri-, di-and mono-glycerides.
基金Youth Top Talents Project in Tianjin Special Support Program,the Science and technology Project of Tianjin(Grant No.21ZYCGSN00410)the Science and technology Project of Tianjin(Grant No.21YDTPJC00910)+4 种基金the National Natural Science Foundation of China[32102004]the Project funded by China Postdoctoral Science Foundation[2021M701169,2022T150206]the China Agriculture Research System of MOF and MARAthe Construction of World Big-leaf Tea Technology Innovation Center and Industrialization of Achievements[202102AE090038]the Scientific and Technological Talents and Platform Plan(Academician Expert Workstation)[202104AC100001-B01].
文摘This study focuses on analyzing aqueous solutions of aroma-active compounds in Xinhui Chenpi distilled after being heated with headspace solid-phase microextraction and gas chromatography-mass spectrometry(HS-SPME-GC/MS).Feasibility of this method was also tested by comparison with crushed samples.The study also analyzed the aqueous solutions of the aroma-active compounds employing gas chromatography-olfactometry(GC-O)defense,aroma extraction dilution analysis(AEDA)and odor activity value(OAV)as well as their emission patterns.According to the study,there are 24 major aroma-active detected in the aqueous solution.Linalool,d-limonene,2-methoxy-4-vinylphenol,andα-terpineol with sweet,spicy,and woody aroma contributed the most to the aroma-active compounds and were considered to be the essential aroma substances of Chenpi.When heated,the aroma of aromatic-active compounds rich in Chenpi volatilized rapidly and the release dropped dramatically in a short time.The substantial aroma-active compounds can be collected from the first ten released segments.
