In this paper,we introduce the censored composite conditional quantile coefficient(cC-CQC)to rank the relative importance of each predictor in high-dimensional censored regression.The cCCQC takes advantage of all usef...In this paper,we introduce the censored composite conditional quantile coefficient(cC-CQC)to rank the relative importance of each predictor in high-dimensional censored regression.The cCCQC takes advantage of all useful information across quantiles and can detect nonlinear effects including interactions and heterogeneity,effectively.Furthermore,the proposed screening method based on cCCQC is robust to the existence of outliers and enjoys the sure screening property.Simulation results demonstrate that the proposed method performs competitively on survival datasets of high-dimensional predictors,particularly when the variables are highly correlated.展开更多
Objective Detection and quantification of RNA synthesis in cells is a widely used technique for monitoring cell viability,health,and metabolic rate.After exposure to environmental stimuli,both the internal reference g...Objective Detection and quantification of RNA synthesis in cells is a widely used technique for monitoring cell viability,health,and metabolic rate.After exposure to environmental stimuli,both the internal reference gene and target gene would be degraded.As a result,it is imperative to consider the accurate capture of nascent RNA and the detection of transcriptional levels of RNA following environmental stimulation.This study aims to create a Click Chemistry method that utilizes its property to capture nascent RNA from total RNA that was stimulated by the environment.Methods The new RNA was labeled with 5-ethyluridine(5-EU)instead of uracil,and the azido-biotin medium ligand was connected to the magnetic sphere using a combination of“Click Chemistry”and magnetic bead screening.Then the new RNA was captured and the transcription rate of 16S rRNA was detected by fluorescence molecular beacon(M.B.)and quantitative reverse transcription PCR(qRT-PCR).Results The bacterial nascent RNA captured by“Click Chemistry”screening can be used as a reverse transcription template to form cDNA.Combined with the fluorescent molecular beacon M.B.1,the synthesis rate of rRNA at 37℃is 1.2 times higher than that at 15℃.The 16S rRNA gene and cspI gene can be detected by fluorescent quantitative PCR,it was found that the measured relative gene expression changes were significantly enhanced at 25℃and 16℃when analyzed with nascent RNA rather than total RNA,enabling accurate detection of RNA transcription rates.Conclusion Compared to other article reported experimental methods that utilize screening magnetic columns,the technical scheme employed in this study is more suitable for bacteria,and the operation steps are simple and easy to implement,making it an effective RNA capture method for researchers.展开更多
The advancement of Clustered Regularly Interspaced Short Palindromic Repeats(CRISPR)gene editing technology has revolutionized the comprehension of human genome,propelling molecular and cellular biology research into ...The advancement of Clustered Regularly Interspaced Short Palindromic Repeats(CRISPR)gene editing technology has revolutionized the comprehension of human genome,propelling molecular and cellular biology research into unexplored realms and accelerating progress in life sciences and medicine.CRISPR-based gene screening,recognized for its efficiency and practicality,is widely utilized across diverse biological fields.Aging is a multifaceted process governed by a myriad of genetic and epigenetic factors.Unraveling the genes regulating aging holds promise for understanding this intricate phenomenon and devising strategies for its assessment and intervention.This review provides a comprehensive overview of the progress in CRISPR screening and its applications in aging research,while also offering insights into future directions.CRISPR-based genetic-manipulation tools are positioned as indispensable instruments for mitigating aging and managing age-related diseases.展开更多
The benzene alkylation process for the production of ethylbenzene has undergone significant improvements during recent decades.Various environmentally benign zeolite-catalyzed ethylbenzene processes,including ZSM-5-ze...The benzene alkylation process for the production of ethylbenzene has undergone significant improvements during recent decades.Various environmentally benign zeolite-catalyzed ethylbenzene processes,including ZSM-5-zeolite-based vapor-phase ethylbenzene processes and Y-,β-,and MCM-22-zeolite-based liquid-phase processes,have been developed and commercialized.Pure ethylene,ethanol,and dilute ethylene have been used as ethylation agents.Here,the development and industrial application of alkylation catalysts and benzene ethylation techniques are summarized,and some other promising innovations are discussed.Recent advances in benzene alkylation over hierarchical zeolites with improved access to active sites and molecular transport are also covered.Zeolites with short diffusion lengths are promising candidates as better alkylation catalysts.The key point is how to obtain such materials easily and economically.The structure-activity relationships of commercial zeolites in these processes are discussed.Liquid-phase processes catalyzed by β and MCM-22 are more profitable than vapor-phase processes catalyzed by ZSM-5.展开更多
Micro-mesoporous ZK-1 molecular sieves with different Si/Al ratios were used as supports for binary Co-Mo hydrodesulfurization(HDS) catalysts.The CoMo/ZK-1 catalysts were prepared using an over-loading impregnation ...Micro-mesoporous ZK-1 molecular sieves with different Si/Al ratios were used as supports for binary Co-Mo hydrodesulfurization(HDS) catalysts.The CoMo/ZK-1 catalysts were prepared using an over-loading impregnation method,and characterized using N2 physisorption,X-ray diffraction,temperature-programmed NH3 desorption,temperature-programmed reduction(TPR),ultraviolet-visible diffuse reflectance spectroscopy,and high-resolution transmission electron microscopy(HRTEM).The results show that the CoMo/ZK-1 catalysts have high surface areas(~700 m^2/g),large pore volumes,and hierarchical porous structures,which promote the dispersion of Co and Mo oxide phases on the ZK-1 supports.The TPR results show that the interactions between the Co and Mo oxide phases and the ZK-1 support are weaker than those in the CoMo/γ-Al2O3 catalyst.The HRTEM results show that the CoMo/ZK-1 catalysts have better MoS2 dispersion and more active edge sites.The catalysts were tested in HDS of dibenzothiophene.Under mild reaction conditions,the activity of Co and Mo sulfides supported on ZK-1 was higher than those of Co and Mo sulfides supported on ZSM-5,A1KIT-1,and γ-Al2O3.展开更多
Volatile organic compounds(VOCs) are a major component in air pollutants and pose great risks to both human health and environmental protection. Currently, VOC abatement in industrial applications is through the use...Volatile organic compounds(VOCs) are a major component in air pollutants and pose great risks to both human health and environmental protection. Currently, VOC abatement in industrial applications is through the use of activated carbons as adsorbents and oxide-supported metals as catalysts. Notably, activated carbons easily adsorb water, which strongly hinders the adsorption of VOCs; conventional oxides typically possess relatively low surface areas and random pores, which effectively influence the catalytic conversion of VOCs. Zeolites, in contrast with activated carbons and oxides, can be designed to have very uniform and controllable micropores, in addition to tailored wettability properties, which can favor the selective adsorption of VOCs. In particular, zeolites with selective adsorptive properties when combined with catalytically active metals result in zeolite-supported metals exhibiting significantly improved performance in the catalytic combustion of VOCs compared with conventional oxide-supported catalysts. In this review, recent developments on VOC abatement by adsorptive and catalytic techniques over zeolite-based materials have been briefly summarized.展开更多
The ZSM-5 zeolite with an unusual snowflake-shaped morphology was hydrothermally synthesized for the first time,and compared with common ellipsoidal and boat-like shaped samples.These samples were characterized by N2 ...The ZSM-5 zeolite with an unusual snowflake-shaped morphology was hydrothermally synthesized for the first time,and compared with common ellipsoidal and boat-like shaped samples.These samples were characterized by N2 adsorption-desorption,X-ray fluorescence spectroscopy,scanning electron microscopy,X-ray diffraction,magic angle spinning nuclear magnetic resonance,temperature-programmed desorption of ammonia,and infrared spectroscopy of pyridine adsorption.The results suggest that the BET surface area and SiO2/Al2O3 ratio of these samples are similar,while the snowflake-shaped ZSM-5 zeolite possesses more of the(101) face,and distortion,dislocation,and asymmetry in the framework,resulting in a larger number of acid sites than the conventional samples.Catalysts for the methanol to olefin(MTO) reaction were prepared by loading Ca on the samples.The snowflake-shaped Ca/ZSM-5 zeolite exhibited excellent selectivity for total light olefin(72%) and propene(39%) in MTO.The catalytic performance influenced by the morphology can be mainly attributed to the snowflake-shaped ZSM-5 zeolite possessing distortion,dislocation,and asymmetry in the framework,and lower diffusion limitation than the conventional samples.展开更多
AFLP analysis was performed between a pair of thermo_sensitive genic male sterile (TGMS) rice allelic mutant lines (5460S and 5460F). The reaction conditions for rice AFLP assay were optimized. The relative efficienci...AFLP analysis was performed between a pair of thermo_sensitive genic male sterile (TGMS) rice allelic mutant lines (5460S and 5460F). The reaction conditions for rice AFLP assay were optimized. The relative efficiencies for polymorphism detection of RFLP, RAPD and AFLP were compared. The results indicated that the efficiency for polymorphism detection in rice was in the order of AFLP>RAPD>RFLP, and also indicated that AFLP was a powerful DNA molecular marker technique for polymorphism detection, especially in the case of extremely low polymorphism, such as isogenic lines and allelic mutant lines. Some of the AFLP products between the TGMS rice allelic mutant lines were cloned. Three of them were used as mixed probes to screen BAC library of rice line 5460S. 12 positive clones were screened out. In addition, the advantages and disadvantages of these three molecular marker systems were discussed.展开更多
[Objective] The aim was to screen out simple methods of DNA extraction and effective ISSR primers suitable to all germplasm materials of Camellia chekiangoleosa.[Method] The modified CTAB method was used in the extrac...[Objective] The aim was to screen out simple methods of DNA extraction and effective ISSR primers suitable to all germplasm materials of Camellia chekiangoleosa.[Method] The modified CTAB method was used in the extraction of the genomic DNA,50 ISSR primers from other Camellia plants were used in the ISSR-PCR amplification for 20 germplasm materials from 10 populations in Fujian,Zhejiang,Jiangxi and Anhui Province.[Result] Pure DNA could be obtained rapidly by using the improved CTAB method,and the 20 selected effective primers had rich polymorphism,clear bands and good repeatability.337 DNA bands were obtained,of which 281 bands were polymorphic,accounting for 83.4% of the total amplified bands.And 16.85 bands could be amplified with a primer,averagely.[Conclusion] The selected 20 primers could be effectively applied to ISSR analysis of the germplasm resources of C.chekiangoleosa in Zhejiang.展开更多
[ Objective] To provide effective primers for the rapid and accurate ISSR analysis of the germplasm materials of Mallotus oblongiolus (Miq.) Muello-Arg.. [Method] The modified CTAB method was used in the extraction ...[ Objective] To provide effective primers for the rapid and accurate ISSR analysis of the germplasm materials of Mallotus oblongiolus (Miq.) Muello-Arg.. [Method] The modified CTAB method was used in the extraction of the genomic DNA. 99 ISSR primers were used in the ISSR-PCR amplification for 20 germplasm materials from 10 populations in Hainan Island, so that some primers, which were suitable to all gerplasm materials of M. oblongiolu, could be selected. [ Result] 15 effective primers with characteristics of rich polymorphism, clear bands, and good repeatability were selected from 99 test primers. The 15 primers selected were used in the ISSR-PCR amplification for 66 germplasm materials of M. oblongiolus. From all of which the abundant and distinct DNA fingerprintings could be obtained. 286 DNA bands were obtained, and of which 231 bands were polymorphic, which amounted to 80.77% of the total bands amplified. And 19.1 bands could be obtained with each primer, averagely. [ Conclusion] The 15 primers selected could be effectively applied to ISSR analysis of the germplasm resources of M. oblongiolus.展开更多
The promoting effect of introducing Zn into nano-ZSM-5 zeolites by conventional impregnation method and isomorphous substitution on the performance of 1-hexene aromatization was investigated. The nano-ZSM-5 zeolite wa...The promoting effect of introducing Zn into nano-ZSM-5 zeolites by conventional impregnation method and isomorphous substitution on the performance of 1-hexene aromatization was investigated. The nano-ZSM-5 zeolite was synthesized by a seed-induced method without organic templates. The Zn-modified nano-ZSM-5 zeolite catalysts, xZ n/HNZ5 and y Zn/Al-HNZ5, were prepared by the conventional impregnation method and isomorphous substitution, respectively. The structure, chemical composition and acidity of the catalysts were characterized by XRD, XRF, N2 adsorption, SEM, NH3-TPD and Py-IR, while the catalytic properties were evaluated at 480 °C and a weight hourly space velocity(WHSV) of 2.0 h-1 in the aromatization procedure of 1-hexene. Compared with xZ n/HNZ5, y Zn/Al-HNZ5 exhibited smaller particles and higher dispersion of Zn species, which led to greater intergranular mesopore and homogeneous acidity distribution. Experimental results indicated that the synergy effect between the Brnsted and Lewis acid sites of the isomorphously substituted nano-ZSM-5 zeolites could significantly increase aromatics yield and improve catalytic stability in the 1-hexene aromatization.展开更多
In order to determine the applicability of microsatellite primers developed from common carp ( Cyprinuscario ) for genomic analysis in mud carp ( Cirrhina molitorella ), 24 primer pairs from common carp were desig...In order to determine the applicability of microsatellite primers developed from common carp ( Cyprinuscario ) for genomic analysis in mud carp ( Cirrhina molitorella ), 24 primer pairs from common carp were designed to amplify microsatellite loci in the mud carp containing CA, GA, AT and GGGA sequences. Thirteen primers (54%) successfully amplified specific products in the mud carp and 11 primers (48%) showed high polymorphism in the mud carp population. The results indicated that the average number of alleles per locus in the mud carp stocks was 5.2. Average heterozygosity (Ho), unbiased expected heterozygosity (He) and polymorphism information content (PIC) in the wild population were 0.61 ± 0.2, 0.8 ± 0.09 and 0.72 ± 0.1 respectively. Several Hardy-Weinberg departure value were significandy departed from Hardy-Weinberg equilibrium. The study showed that microsatellite primers from a species of Cyprinidae can be used for mud carp genetic analysis without much cost or time input.展开更多
[Objective] Simple and reliable identification criteria used in screening phosphorus efficiency of soybean at seedling stage was discussed.[Method] Using the high and low phosphorus soil pot experiment,the soybean see...[Objective] Simple and reliable identification criteria used in screening phosphorus efficiency of soybean at seedling stage was discussed.[Method] Using the high and low phosphorus soil pot experiment,the soybean seedling stage's 5 criteria including RPH,RAW,RRW,RAPC and RRPC were studied.[Result] Low phosphorus stress had the low effects on relative plant height,the coefficient of variation was only 9.07%,has not achieved the remarkable level with its its criteria's relevance;Low phosphorus stress had the higher effects on relatively above-ground dry weight and relative dry weight of root,relatively above-ground phosphorus concentration and relative root phosphorus concentration,its coefficient of variation was also big,in turn is 26.67%,22.68%,24.01% and 15.87%,The correlation coefficient among the indicators had significantly or extremely significantly positive correlation.[Conclusion] Relatively above-ground dry weight and relative dry weight of root,relatively above-ground phosphorus concentration can be used as an important indicator of comprehensive evaluation of screening phosphorus efficiency of soybean at seedling stage,while the relative root phosphorus concentration can be used as secondary screening index.展开更多
The structure and catalytic properties of PtSn catalysts supported on SUZ-4 and ZSM-5 zeolite have been studied by using various experimental techniques including XRD,nitrogen adsorption,NH3-TPD,TG,H2-TPR and TPO tech...The structure and catalytic properties of PtSn catalysts supported on SUZ-4 and ZSM-5 zeolite have been studied by using various experimental techniques including XRD,nitrogen adsorption,NH3-TPD,TG,H2-TPR and TPO techniques combined with propane dehydrogenation tests.It has been shown that SUZ-4-supported PtSnNa(PtSnNa/SUZ-4) was determined to be a better catalyst for propane dehydrogenation than conventional catalysts supported on ZSM-5,owing to its higher catalytic activity and stability.Dibenzothiophene poisoning experiments were performed to investigate the detailed structures of the two supported catalysts.The characterization of the two catalysts indicates that the distribution of Pt on the porous support affects the activity.In contrast to ZSM-5-supported catalysts,Pt particles on the PtSnNa/SUZ-4 are primarily dispersed over the external surface and are not as readily deactivated by carbon deposition.This is because that the strong acid sites of the SUZ-4 zeolite evidently prevented the impregnation of the Pt precursor H_2PtCl_6 into the zeolite.In contrast,the weak acid sites of the ZSM-5 zeolite led to more of the precursor entering the zeolite tunnels,followed by transformation to highly dispersed Pt clusters during calcination.In the case of the PtSnNa/ZSM-5,the interactions between Sn oxides and the support were lessened,owing to the weaker acidity of the ZSM-5 zeolite.The dispersed Sn oxides were therefore easier to reduce to the metallic state,thus decreasing the catalytic activity for hydrocarbon dehydrogenation.展开更多
[ Objective] The aim of this study was to isolate the endophyte of three solanaceae fruits and vegetables such as tomato, pepper and eggplant, to screen and identify the bacterial wilt antagonistic bacteria. [ Methodl...[ Objective] The aim of this study was to isolate the endophyte of three solanaceae fruits and vegetables such as tomato, pepper and eggplant, to screen and identify the bacterial wilt antagonistic bacteria. [ Methodl According to the lapping liquid culture method, the endophyte of three plants was isolated by the selective medium and purified by the plate streaking method, so the purified enclophyte was screened by the hyphal pieces confront culture method. Furthermore, the screened antagonistic and endophyteic bacteria was identified and classified through culture characteristics of isolates and morphological features of thallus, Gram stain as well as physiological and biochemical reactions. [ Result] Fifty-three endophytic bacteria, fifty-three endophytic fungi and forty-four endophytic actinomycetes were separated from the endophyte of three plants. The screened fourteen endophytic bacteria with strong antagonistic effect on the bacterial wilt were classified to Bacillus, Escherichia, Klebsiella, Agromonas, Erwinia and Curto Bacterium respectively. Especially, Bacillus was the dominant species, which had the strongest antagonistic effect on the bacterial wilt. [ Conclusion] This study provides an effective way for biological control of the bacterial wilt in solanaceae.展开更多
[ Objective] The aim of this study was to lay a foundation for obtaining effective traditional Chinese medicine preparations controlling chicken colibacillosis. [ Method] With the western medicine Lomeflbxacin Hydroch...[ Objective] The aim of this study was to lay a foundation for obtaining effective traditional Chinese medicine preparations controlling chicken colibacillosis. [ Method] With the western medicine Lomeflbxacin Hydrochloride and Sodium Chloride Injection as the control, drug sensitivity tests of 15 single traditional Chinese herbs and seven self-made Chinese herbal compounds were conducted. Subsequently, the single traditional Chinese herbs presenting good in vitro antibacterial effects against Escherichia coli and all the seven compounds were given to the chicks artificially infected with E. coil to observe their efficacies. [ Result] The results of drug sensitivity tests showed that all the 15 traditional Chinese herbs had certain antibacterial effect against E. coli, among which aloe, pomegranate rind and radix sanguisorbae were the best. Compound 1, 2 and 5 had good antibacterial effects in vitro. By in vivo test, traditional Chinese medicines showed superior efficacies on infected chicks than western medicine, and compound 1 and 2 performed well. [ConclusiOn] Traditional Chinese medicine preparations are good at controlling Chicken colibacillosis, but their bacteriostasis mechanism in vivo was different with that in vitro.展开更多
[Objective] The aim was to separate chromium-resistant microorganism from soil contaminated by chromium.[Method] Separation and purification technique was used as follows:different concentrations of Cr^6+ were added...[Objective] The aim was to separate chromium-resistant microorganism from soil contaminated by chromium.[Method] Separation and purification technique was used as follows:different concentrations of Cr^6+ were added into medium,and chromium-resistant fungi were screened after separations and domestications.The selected fungi were under preliminary identification according to its morphological and colony characteristics.Then,related biological characteristics were studied,including measurement of growth curve,growing effects by temperature,pH value and osmotic pressure.[Result] The Cr(VI) with concentration of 1 000 mg/L was separated and selected from soils in ten different places contaminated seriously by heavy metal in adjacent region of Yulin City.Considering its morphological and colony characteristics,it was preliminarily identified as saccharomycetes,which can well grow within 15-37 ℃,and whose most suitable temperature was 28℃.Bacterial strain can grow well with pH of 4-10,and the optimum pH was 7.2;besides,it can grow well with NaCl concentration of 0.5%-5.0%.Through the experiment,the bacteria was found with resistance not only to chromium,but also to heavy metals such as Pb+Cu,Cu+Fe,Pb+Fe,and Pb+Cu+Fe.[Conclusion] The fungi selected from the experiment were of good adaptability to natural environment,and it also had resistance to other heavy metals.展开更多
Literature lacked in providing a comprehensive research on heavy metal detection in aquatic, biological and sedimentary states of rivers. The present study was imparted with all these three components of the river. He...Literature lacked in providing a comprehensive research on heavy metal detection in aquatic, biological and sedimentary states of rivers. The present study was imparted with all these three components of the river. Heavy metal toxicity or pollution index was used as a tool for ecological risk assessment by considering the single state studies conducted by many researchers. An intensive ecological risk assessment model was constructed and heavy metals were indicated as a serious threat to the environment. The model was applied to determining five toxic heavy metals in three states of the Songhua River. According to the ecological risk index, heavy metal pollution in three phases was categorized as aquatic〉biological〉sedimentary, while the overall descending order of heavy metal ecological risk index was as Cd〉Hg〉As〉Pb〉Cr. Cd and Hg were selected as the priority pollutants of Songhua River.展开更多
[Objective] The research aimed to obtain an effectively-decomposing strain of silkworm chrysalis protein and discuss its enzymatic properties.[Method] The effectively-decomposing bacteria of protein was isolated from ...[Objective] The research aimed to obtain an effectively-decomposing strain of silkworm chrysalis protein and discuss its enzymatic properties.[Method] The effectively-decomposing bacteria of protein was isolated from the decayed silkworm chrysalis by using dilution plate and its enzymatic properties were tested after primary screening and second screening.The enzyme activity was determined and the intermediate and small molecule protein content in silkworm chrysalis was measured after solid-state fermentati...展开更多
基金Outstanding Youth Foundation of Hunan Provincial Department of Education(Grant No.22B0911)。
文摘In this paper,we introduce the censored composite conditional quantile coefficient(cC-CQC)to rank the relative importance of each predictor in high-dimensional censored regression.The cCCQC takes advantage of all useful information across quantiles and can detect nonlinear effects including interactions and heterogeneity,effectively.Furthermore,the proposed screening method based on cCCQC is robust to the existence of outliers and enjoys the sure screening property.Simulation results demonstrate that the proposed method performs competitively on survival datasets of high-dimensional predictors,particularly when the variables are highly correlated.
文摘Objective Detection and quantification of RNA synthesis in cells is a widely used technique for monitoring cell viability,health,and metabolic rate.After exposure to environmental stimuli,both the internal reference gene and target gene would be degraded.As a result,it is imperative to consider the accurate capture of nascent RNA and the detection of transcriptional levels of RNA following environmental stimulation.This study aims to create a Click Chemistry method that utilizes its property to capture nascent RNA from total RNA that was stimulated by the environment.Methods The new RNA was labeled with 5-ethyluridine(5-EU)instead of uracil,and the azido-biotin medium ligand was connected to the magnetic sphere using a combination of“Click Chemistry”and magnetic bead screening.Then the new RNA was captured and the transcription rate of 16S rRNA was detected by fluorescence molecular beacon(M.B.)and quantitative reverse transcription PCR(qRT-PCR).Results The bacterial nascent RNA captured by“Click Chemistry”screening can be used as a reverse transcription template to form cDNA.Combined with the fluorescent molecular beacon M.B.1,the synthesis rate of rRNA at 37℃is 1.2 times higher than that at 15℃.The 16S rRNA gene and cspI gene can be detected by fluorescent quantitative PCR,it was found that the measured relative gene expression changes were significantly enhanced at 25℃and 16℃when analyzed with nascent RNA rather than total RNA,enabling accurate detection of RNA transcription rates.Conclusion Compared to other article reported experimental methods that utilize screening magnetic columns,the technical scheme employed in this study is more suitable for bacteria,and the operation steps are simple and easy to implement,making it an effective RNA capture method for researchers.
文摘The advancement of Clustered Regularly Interspaced Short Palindromic Repeats(CRISPR)gene editing technology has revolutionized the comprehension of human genome,propelling molecular and cellular biology research into unexplored realms and accelerating progress in life sciences and medicine.CRISPR-based gene screening,recognized for its efficiency and practicality,is widely utilized across diverse biological fields.Aging is a multifaceted process governed by a myriad of genetic and epigenetic factors.Unraveling the genes regulating aging holds promise for understanding this intricate phenomenon and devising strategies for its assessment and intervention.This review provides a comprehensive overview of the progress in CRISPR screening and its applications in aging research,while also offering insights into future directions.CRISPR-based genetic-manipulation tools are positioned as indispensable instruments for mitigating aging and managing age-related diseases.
文摘The benzene alkylation process for the production of ethylbenzene has undergone significant improvements during recent decades.Various environmentally benign zeolite-catalyzed ethylbenzene processes,including ZSM-5-zeolite-based vapor-phase ethylbenzene processes and Y-,β-,and MCM-22-zeolite-based liquid-phase processes,have been developed and commercialized.Pure ethylene,ethanol,and dilute ethylene have been used as ethylation agents.Here,the development and industrial application of alkylation catalysts and benzene ethylation techniques are summarized,and some other promising innovations are discussed.Recent advances in benzene alkylation over hierarchical zeolites with improved access to active sites and molecular transport are also covered.Zeolites with short diffusion lengths are promising candidates as better alkylation catalysts.The key point is how to obtain such materials easily and economically.The structure-activity relationships of commercial zeolites in these processes are discussed.Liquid-phase processes catalyzed by β and MCM-22 are more profitable than vapor-phase processes catalyzed by ZSM-5.
基金financially supported by the National Natural Science Foundation of China (NNSFC,21206017)~~
文摘Micro-mesoporous ZK-1 molecular sieves with different Si/Al ratios were used as supports for binary Co-Mo hydrodesulfurization(HDS) catalysts.The CoMo/ZK-1 catalysts were prepared using an over-loading impregnation method,and characterized using N2 physisorption,X-ray diffraction,temperature-programmed NH3 desorption,temperature-programmed reduction(TPR),ultraviolet-visible diffuse reflectance spectroscopy,and high-resolution transmission electron microscopy(HRTEM).The results show that the CoMo/ZK-1 catalysts have high surface areas(~700 m^2/g),large pore volumes,and hierarchical porous structures,which promote the dispersion of Co and Mo oxide phases on the ZK-1 supports.The TPR results show that the interactions between the Co and Mo oxide phases and the ZK-1 support are weaker than those in the CoMo/γ-Al2O3 catalyst.The HRTEM results show that the CoMo/ZK-1 catalysts have better MoS2 dispersion and more active edge sites.The catalysts were tested in HDS of dibenzothiophene.Under mild reaction conditions,the activity of Co and Mo sulfides supported on ZK-1 was higher than those of Co and Mo sulfides supported on ZSM-5,A1KIT-1,and γ-Al2O3.
基金supported by the Fundamental Research Funds for the Central Universities(2015XZZX004-04)Zhejiang Provincial Natural Science Foundation(LR15B030001)~~
文摘Volatile organic compounds(VOCs) are a major component in air pollutants and pose great risks to both human health and environmental protection. Currently, VOC abatement in industrial applications is through the use of activated carbons as adsorbents and oxide-supported metals as catalysts. Notably, activated carbons easily adsorb water, which strongly hinders the adsorption of VOCs; conventional oxides typically possess relatively low surface areas and random pores, which effectively influence the catalytic conversion of VOCs. Zeolites, in contrast with activated carbons and oxides, can be designed to have very uniform and controllable micropores, in addition to tailored wettability properties, which can favor the selective adsorption of VOCs. In particular, zeolites with selective adsorptive properties when combined with catalytically active metals result in zeolite-supported metals exhibiting significantly improved performance in the catalytic combustion of VOCs compared with conventional oxide-supported catalysts. In this review, recent developments on VOC abatement by adsorptive and catalytic techniques over zeolite-based materials have been briefly summarized.
基金Synfuels China Co.Ltd.for the financial and equipments support
文摘The ZSM-5 zeolite with an unusual snowflake-shaped morphology was hydrothermally synthesized for the first time,and compared with common ellipsoidal and boat-like shaped samples.These samples were characterized by N2 adsorption-desorption,X-ray fluorescence spectroscopy,scanning electron microscopy,X-ray diffraction,magic angle spinning nuclear magnetic resonance,temperature-programmed desorption of ammonia,and infrared spectroscopy of pyridine adsorption.The results suggest that the BET surface area and SiO2/Al2O3 ratio of these samples are similar,while the snowflake-shaped ZSM-5 zeolite possesses more of the(101) face,and distortion,dislocation,and asymmetry in the framework,resulting in a larger number of acid sites than the conventional samples.Catalysts for the methanol to olefin(MTO) reaction were prepared by loading Ca on the samples.The snowflake-shaped Ca/ZSM-5 zeolite exhibited excellent selectivity for total light olefin(72%) and propene(39%) in MTO.The catalytic performance influenced by the morphology can be mainly attributed to the snowflake-shaped ZSM-5 zeolite possessing distortion,dislocation,and asymmetry in the framework,and lower diffusion limitation than the conventional samples.
文摘AFLP analysis was performed between a pair of thermo_sensitive genic male sterile (TGMS) rice allelic mutant lines (5460S and 5460F). The reaction conditions for rice AFLP assay were optimized. The relative efficiencies for polymorphism detection of RFLP, RAPD and AFLP were compared. The results indicated that the efficiency for polymorphism detection in rice was in the order of AFLP>RAPD>RFLP, and also indicated that AFLP was a powerful DNA molecular marker technique for polymorphism detection, especially in the case of extremely low polymorphism, such as isogenic lines and allelic mutant lines. Some of the AFLP products between the TGMS rice allelic mutant lines were cloned. Three of them were used as mixed probes to screen BAC library of rice line 5460S. 12 positive clones were screened out. In addition, the advantages and disadvantages of these three molecular marker systems were discussed.
基金Supported by Project of Zhejiang Provincial Department of Scienceand Technology(2010C32043)~~
文摘[Objective] The aim was to screen out simple methods of DNA extraction and effective ISSR primers suitable to all germplasm materials of Camellia chekiangoleosa.[Method] The modified CTAB method was used in the extraction of the genomic DNA,50 ISSR primers from other Camellia plants were used in the ISSR-PCR amplification for 20 germplasm materials from 10 populations in Fujian,Zhejiang,Jiangxi and Anhui Province.[Result] Pure DNA could be obtained rapidly by using the improved CTAB method,and the 20 selected effective primers had rich polymorphism,clear bands and good repeatability.337 DNA bands were obtained,of which 281 bands were polymorphic,accounting for 83.4% of the total amplified bands.And 16.85 bands could be amplified with a primer,averagely.[Conclusion] The selected 20 primers could be effectively applied to ISSR analysis of the germplasm resources of C.chekiangoleosa in Zhejiang.
基金Supported by Special Fund for Key Disciplines Program of HainanUniversity~~
文摘[ Objective] To provide effective primers for the rapid and accurate ISSR analysis of the germplasm materials of Mallotus oblongiolus (Miq.) Muello-Arg.. [Method] The modified CTAB method was used in the extraction of the genomic DNA. 99 ISSR primers were used in the ISSR-PCR amplification for 20 germplasm materials from 10 populations in Hainan Island, so that some primers, which were suitable to all gerplasm materials of M. oblongiolu, could be selected. [ Result] 15 effective primers with characteristics of rich polymorphism, clear bands, and good repeatability were selected from 99 test primers. The 15 primers selected were used in the ISSR-PCR amplification for 66 germplasm materials of M. oblongiolus. From all of which the abundant and distinct DNA fingerprintings could be obtained. 286 DNA bands were obtained, and of which 231 bands were polymorphic, which amounted to 80.77% of the total bands amplified. And 19.1 bands could be obtained with each primer, averagely. [ Conclusion] The 15 primers selected could be effectively applied to ISSR analysis of the germplasm resources of M. oblongiolus.
基金Project(21276067)supported by the National Natural Science Foundation of China
文摘The promoting effect of introducing Zn into nano-ZSM-5 zeolites by conventional impregnation method and isomorphous substitution on the performance of 1-hexene aromatization was investigated. The nano-ZSM-5 zeolite was synthesized by a seed-induced method without organic templates. The Zn-modified nano-ZSM-5 zeolite catalysts, xZ n/HNZ5 and y Zn/Al-HNZ5, were prepared by the conventional impregnation method and isomorphous substitution, respectively. The structure, chemical composition and acidity of the catalysts were characterized by XRD, XRF, N2 adsorption, SEM, NH3-TPD and Py-IR, while the catalytic properties were evaluated at 480 °C and a weight hourly space velocity(WHSV) of 2.0 h-1 in the aromatization procedure of 1-hexene. Compared with xZ n/HNZ5, y Zn/Al-HNZ5 exhibited smaller particles and higher dispersion of Zn species, which led to greater intergranular mesopore and homogeneous acidity distribution. Experimental results indicated that the synergy effect between the Brnsted and Lewis acid sites of the isomorphously substituted nano-ZSM-5 zeolites could significantly increase aromatics yield and improve catalytic stability in the 1-hexene aromatization.
文摘In order to determine the applicability of microsatellite primers developed from common carp ( Cyprinuscario ) for genomic analysis in mud carp ( Cirrhina molitorella ), 24 primer pairs from common carp were designed to amplify microsatellite loci in the mud carp containing CA, GA, AT and GGGA sequences. Thirteen primers (54%) successfully amplified specific products in the mud carp and 11 primers (48%) showed high polymorphism in the mud carp population. The results indicated that the average number of alleles per locus in the mud carp stocks was 5.2. Average heterozygosity (Ho), unbiased expected heterozygosity (He) and polymorphism information content (PIC) in the wild population were 0.61 ± 0.2, 0.8 ± 0.09 and 0.72 ± 0.1 respectively. Several Hardy-Weinberg departure value were significandy departed from Hardy-Weinberg equilibrium. The study showed that microsatellite primers from a species of Cyprinidae can be used for mud carp genetic analysis without much cost or time input.
基金Supported by Foundation of Heilongjiang Provincial Department of Education"Biological Basis of the Roots from Different Soybean Genotypes Adapting to Low-phosphorus Soil"(10551033)Scientific Research Startup Foundation for Doctor Program of Mudanjiang Normal University(MSB200912)~~
文摘[Objective] Simple and reliable identification criteria used in screening phosphorus efficiency of soybean at seedling stage was discussed.[Method] Using the high and low phosphorus soil pot experiment,the soybean seedling stage's 5 criteria including RPH,RAW,RRW,RAPC and RRPC were studied.[Result] Low phosphorus stress had the low effects on relative plant height,the coefficient of variation was only 9.07%,has not achieved the remarkable level with its its criteria's relevance;Low phosphorus stress had the higher effects on relatively above-ground dry weight and relative dry weight of root,relatively above-ground phosphorus concentration and relative root phosphorus concentration,its coefficient of variation was also big,in turn is 26.67%,22.68%,24.01% and 15.87%,The correlation coefficient among the indicators had significantly or extremely significantly positive correlation.[Conclusion] Relatively above-ground dry weight and relative dry weight of root,relatively above-ground phosphorus concentration can be used as an important indicator of comprehensive evaluation of screening phosphorus efficiency of soybean at seedling stage,while the relative root phosphorus concentration can be used as secondary screening index.
基金supported by the Jiangsu Planned Projects for Postdoctoral Research Funds(1301080C)NNSFC(21202141,21173182)+1 种基金Key Science&Technology Specific Projects of Yangzhou(YZ20122029)the Innovation Foundation of Yangzhou University(2015CXJ009)~~
文摘The structure and catalytic properties of PtSn catalysts supported on SUZ-4 and ZSM-5 zeolite have been studied by using various experimental techniques including XRD,nitrogen adsorption,NH3-TPD,TG,H2-TPR and TPO techniques combined with propane dehydrogenation tests.It has been shown that SUZ-4-supported PtSnNa(PtSnNa/SUZ-4) was determined to be a better catalyst for propane dehydrogenation than conventional catalysts supported on ZSM-5,owing to its higher catalytic activity and stability.Dibenzothiophene poisoning experiments were performed to investigate the detailed structures of the two supported catalysts.The characterization of the two catalysts indicates that the distribution of Pt on the porous support affects the activity.In contrast to ZSM-5-supported catalysts,Pt particles on the PtSnNa/SUZ-4 are primarily dispersed over the external surface and are not as readily deactivated by carbon deposition.This is because that the strong acid sites of the SUZ-4 zeolite evidently prevented the impregnation of the Pt precursor H_2PtCl_6 into the zeolite.In contrast,the weak acid sites of the ZSM-5 zeolite led to more of the precursor entering the zeolite tunnels,followed by transformation to highly dispersed Pt clusters during calcination.In the case of the PtSnNa/ZSM-5,the interactions between Sn oxides and the support were lessened,owing to the weaker acidity of the ZSM-5 zeolite.The dispersed Sn oxides were therefore easier to reduce to the metallic state,thus decreasing the catalytic activity for hydrocarbon dehydrogenation.
文摘[ Objective] The aim of this study was to isolate the endophyte of three solanaceae fruits and vegetables such as tomato, pepper and eggplant, to screen and identify the bacterial wilt antagonistic bacteria. [ Methodl According to the lapping liquid culture method, the endophyte of three plants was isolated by the selective medium and purified by the plate streaking method, so the purified enclophyte was screened by the hyphal pieces confront culture method. Furthermore, the screened antagonistic and endophyteic bacteria was identified and classified through culture characteristics of isolates and morphological features of thallus, Gram stain as well as physiological and biochemical reactions. [ Result] Fifty-three endophytic bacteria, fifty-three endophytic fungi and forty-four endophytic actinomycetes were separated from the endophyte of three plants. The screened fourteen endophytic bacteria with strong antagonistic effect on the bacterial wilt were classified to Bacillus, Escherichia, Klebsiella, Agromonas, Erwinia and Curto Bacterium respectively. Especially, Bacillus was the dominant species, which had the strongest antagonistic effect on the bacterial wilt. [ Conclusion] This study provides an effective way for biological control of the bacterial wilt in solanaceae.
基金Supported by Fund of Education Department in Hebei Province(2007408)~~
文摘[ Objective] The aim of this study was to lay a foundation for obtaining effective traditional Chinese medicine preparations controlling chicken colibacillosis. [ Method] With the western medicine Lomeflbxacin Hydrochloride and Sodium Chloride Injection as the control, drug sensitivity tests of 15 single traditional Chinese herbs and seven self-made Chinese herbal compounds were conducted. Subsequently, the single traditional Chinese herbs presenting good in vitro antibacterial effects against Escherichia coli and all the seven compounds were given to the chicks artificially infected with E. coil to observe their efficacies. [ Result] The results of drug sensitivity tests showed that all the 15 traditional Chinese herbs had certain antibacterial effect against E. coli, among which aloe, pomegranate rind and radix sanguisorbae were the best. Compound 1, 2 and 5 had good antibacterial effects in vitro. By in vivo test, traditional Chinese medicines showed superior efficacies on infected chicks than western medicine, and compound 1 and 2 performed well. [ConclusiOn] Traditional Chinese medicine preparations are good at controlling Chicken colibacillosis, but their bacteriostasis mechanism in vivo was different with that in vitro.
基金Supported by Chinese National Natural Science Foundation(30960008 )Educational Commission of Guangxi Province(200810LX393)+2 种基金Starting Project of Yulin Normal College,Guangxi ProvinceSpecialized Research Project of Yulin Normal College,Guangxi Province (2011YJZX01)Project Supported by the Science Foundation for Young Scientists of Guangxi Yulin Normal College (2010YJQN24)~~
文摘[Objective] The aim was to separate chromium-resistant microorganism from soil contaminated by chromium.[Method] Separation and purification technique was used as follows:different concentrations of Cr^6+ were added into medium,and chromium-resistant fungi were screened after separations and domestications.The selected fungi were under preliminary identification according to its morphological and colony characteristics.Then,related biological characteristics were studied,including measurement of growth curve,growing effects by temperature,pH value and osmotic pressure.[Result] The Cr(VI) with concentration of 1 000 mg/L was separated and selected from soils in ten different places contaminated seriously by heavy metal in adjacent region of Yulin City.Considering its morphological and colony characteristics,it was preliminarily identified as saccharomycetes,which can well grow within 15-37 ℃,and whose most suitable temperature was 28℃.Bacterial strain can grow well with pH of 4-10,and the optimum pH was 7.2;besides,it can grow well with NaCl concentration of 0.5%-5.0%.Through the experiment,the bacteria was found with resistance not only to chromium,but also to heavy metals such as Pb+Cu,Cu+Fe,Pb+Fe,and Pb+Cu+Fe.[Conclusion] The fungi selected from the experiment were of good adaptability to natural environment,and it also had resistance to other heavy metals.
基金Project(2010467038)supported by the Special Fund for Environmental Research in the Public Interest,China
文摘Literature lacked in providing a comprehensive research on heavy metal detection in aquatic, biological and sedimentary states of rivers. The present study was imparted with all these three components of the river. Heavy metal toxicity or pollution index was used as a tool for ecological risk assessment by considering the single state studies conducted by many researchers. An intensive ecological risk assessment model was constructed and heavy metals were indicated as a serious threat to the environment. The model was applied to determining five toxic heavy metals in three states of the Songhua River. According to the ecological risk index, heavy metal pollution in three phases was categorized as aquatic〉biological〉sedimentary, while the overall descending order of heavy metal ecological risk index was as Cd〉Hg〉As〉Pb〉Cr. Cd and Hg were selected as the priority pollutants of Songhua River.
基金Supported by Agricultural Key Project of Guangdong Province(2007A0201000043)Key Bidding Projects in Key Fields of Guangdong and Hongkong(2006A25001002)Special Fund for the Construction of National Modern Agro-industry Technology System~~
文摘[Objective] The research aimed to obtain an effectively-decomposing strain of silkworm chrysalis protein and discuss its enzymatic properties.[Method] The effectively-decomposing bacteria of protein was isolated from the decayed silkworm chrysalis by using dilution plate and its enzymatic properties were tested after primary screening and second screening.The enzyme activity was determined and the intermediate and small molecule protein content in silkworm chrysalis was measured after solid-state fermentati...