Virtual machine(VM)consolidation is an effective way to improve resource utilization and reduce energy consumption in cloud data centers.Most existing studies have considered VM consolidation as a bin-packing problem,...Virtual machine(VM)consolidation is an effective way to improve resource utilization and reduce energy consumption in cloud data centers.Most existing studies have considered VM consolidation as a bin-packing problem,but the current schemes commonly ignore the long-term relationship between VMs and hosts.In addition,there is a lack of long-term consideration for resource optimization in the VM consolidation,which results in unnecessary VM migration and increased energy consumption.To address these limitations,a VM consolidation method based on multi-step prediction and affinity-aware technique for energy-efficient cloud data centers(MPaAF-VMC)is proposed.The proposed method uses an improved linear regression prediction algorithm to predict the next-moment resource utilization of hosts and VMs,and obtains the stage demand of resources in the future period through multi-step prediction,which is realized by iterative prediction.Then,based on the multi-step prediction,an affinity model between the VM and host is designed using the first-order correlation coefficient and Euclidean distance.During the VM consolidation,the affinity value is used to select the migration VM and placement host.The proposed method is compared with the existing consolidation algorithms on the PlanetLab and Google cluster real workload data using the CloudSim simulation platform.Experimental results show that the proposed method can achieve significant improvement in reducing energy consumption,VM migration costs,and service level agreement(SLA)violations.展开更多
The formulae for parameters of a negative electron affinity semiconductor(NEAS)with large mean escape depth of secondary electrons A(NEASLD)are deduced.The methods for obtaining parameters such asλ,B,E_(pom)and the m...The formulae for parameters of a negative electron affinity semiconductor(NEAS)with large mean escape depth of secondary electrons A(NEASLD)are deduced.The methods for obtaining parameters such asλ,B,E_(pom)and the maximumδandδat 100.0 keV≥E_(po)≥1.0 keV of a NEASLD with the deduced formulae are presented(B is the probability that an internal secondary electron escapes into the vacuum upon reaching the emission surface of the emitter,δis the secondary electron yield,E_(po)is the incident energy of primary electrons and E_(pom)is the E_(po)corresponding to the maximumδ).The parameters obtained here are analyzed,and it can be concluded that several parameters of NEASLDs obtained by the methods presented here agree with those obtained by other authors.The relation between the secondary electron emission and photoemission from a NEAS with large mean escape depth of excited electrons is investigated,and it is concluded that the presented method of obtaining A is more accurate than that of obtaining the corresponding parameter for a NEAS with largeλ_(ph)(λ_(ph)being the mean escape depth of photoelectrons),and that the presented method of calculating B at E_(po)>10.0 keV is more widely applicable for obtaining the corresponding parameters for a NEAS with largeλ_(ph).展开更多
Affinity propagation(AP)is a widely used exemplar-based clustering approach with superior efficiency and clustering quality.Nevertheless,a common issue with AP clustering is the presence of excessive exemplars,which l...Affinity propagation(AP)is a widely used exemplar-based clustering approach with superior efficiency and clustering quality.Nevertheless,a common issue with AP clustering is the presence of excessive exemplars,which limits its ability to perform effective aggregation.This research aims to enable AP to automatically aggregate to produce fewer and more compact clusters,without changing the similarity matrix or customizing preference parameters,as done in existing enhanced approaches.An automatic aggregation enhanced affinity propagation(AAEAP)clustering algorithm is proposed,which combines a dependable partitioning clustering approach with AP to achieve this purpose.The partitioning clustering approach generates an additional set of findings with an equivalent number of clusters whenever the clustering stabilizes and the exemplars emerge.Based on these findings,mutually exclusive exemplar detection was conducted on the current AP exemplars,and a pair of unsuitable exemplars for coexistence is recommended.The recommendation is then mapped as a novel constraint,designated mutual exclusion and aggregation.To address this limitation,a modified AP clustering model is derived and the clustering is restarted,which can result in exemplar number reduction,exemplar selection adjustment,and other data point redistribution.The clustering is ultimately completed and a smaller number of clusters are obtained by repeatedly performing automatic detection and clustering until no mutually exclusive exemplars are detected.Some standard classification data sets are adopted for experiments on AAEAP and other clustering algorithms for comparison,and many internal and external clustering evaluation indexes are used to measure the clustering performance.The findings demonstrate that the AAEAP clustering algorithm demonstrates a substantial automatic aggregation impact while maintaining good clustering quality.展开更多
Drug target relationship(DTR)prediction is a rapidly evolving area of research in com-putational drug discovery.Despite recent advances in computational solutions that have overcome the challenges of in vitro and in v...Drug target relationship(DTR)prediction is a rapidly evolving area of research in com-putational drug discovery.Despite recent advances in computational solutions that have overcome the challenges of in vitro and in vivo experiments,most computational methods still focus on binary classification.They ignore the importance of binding affinity,which correctly distinguishes between on-targets and off-targets.In this study,we propose a deep learning model based on the microstruc-ture of compounds and proteins to predict drug-target binding affinity(DTA),which utilizes topo-logical structure information of drug molecules and sequence semantic information of proteins.In this model,graph attention network(GAT)is used to capture the deep features of the compound molecular graph,and bidirectional long short-term memory(BiLSTM)network is used to extract the protein sequence features,and the pharmacological context of DTA is obtained by combining the two.The results show that the proposed model has achieved superior performance in both cor-rectly predicting the value of interaction strength and correctly discriminating the ranking of bind-ing strength compared to the state-of-the-art baselines.A case study experiment on COVID-19 con-firms that the proposed DTA model can be used as an effective pre-screening tool in drug discovery.展开更多
We describe a two-step method that uses wheat germ agglutinin immobilized on Sepharose gel followed by immunoaffinity chromatography (IAC) to extract recombinant human erythropoietin and Darbepoetin from equine plasma...We describe a two-step method that uses wheat germ agglutinin immobilized on Sepharose gel followed by immunoaffinity chromatography (IAC) to extract recombinant human erythropoietin and Darbepoetin from equine plasma. Lectin affinity chromatography was shown to be an effective approach for isolating these epoetins from plasma and in combination with IAC;this method gave superior recovery when compared to the use of the latter technique alone. Moreover, due to the ease with which it can be scaled up, it is particularly well suited for pre-concentrating larger volumes of samples prior to IAC and this provides a facile way of improving the overall sensitivity with which these foreign proteins can be detected in equine plasma.展开更多
Attempts were made to develop dyes with high affinity for polylactide as an alternative to the existent commercial disperse dyes. The dyes synthesized according to the affinity concept of dye to polylactide exhibited ...Attempts were made to develop dyes with high affinity for polylactide as an alternative to the existent commercial disperse dyes. The dyes synthesized according to the affinity concept of dye to polylactide exhibited excellent dyeing properties on polylactide compared with the commercial disperse dyes.展开更多
A new series of bone affinity compounds were synthesized by linking emodin with 5-fluorouracil derivatives. Their bone affinities were established by hydroxyapative (HA) affinity experiment in vitro, and their cytosta...A new series of bone affinity compounds were synthesized by linking emodin with 5-fluorouracil derivatives. Their bone affinities were established by hydroxyapative (HA) affinity experiment in vitro, and their cytostatic effects were shown by the MTT assay.展开更多
An affinity membrane was prepared by coaxial electrospinning and amidoxime(AONFA),and it was applied to selectively recovery Au(Ⅲ)from an aqueous solution.The static adsorption results showed that,when p H at 5,the m...An affinity membrane was prepared by coaxial electrospinning and amidoxime(AONFA),and it was applied to selectively recovery Au(Ⅲ)from an aqueous solution.The static adsorption results showed that,when p H at 5,the maximum adsorption capacity of AONFA membrane for Au(Ⅲ)was 509.3 mg·g^(-1).AONFA membrane exhibit much higher affinity and selectivity towards Au(Ⅲ)than other metal cations.The membrane could be regenerated effectively by mixture solution of thiourea and HCl,and the desorption ratio reached almost 100%after 4 hours desorption.The dead-end filtration results showed that,the membrane utilization efficiency and adsorption capacity can be improved by increasing the flow rate,while increasing the concentration shorted the breakthrough process and had little impact to adsorption capacity.We can flexibly adjust the flow rate and concentration according to the situation to obtain the maximum utilization efficiency of the membrane in filtration process.The dynamic adsorption capacity is higher than the static adsorption capacity.The adsorption mechanism for Au(Ⅲ)is electrostatic adsorption and reduction.Thus,AONFA membrane filtration was demonstrated to be a promising method for continuous recover Au(Ⅲ)from wastewater.展开更多
Commercial paper is of great potential as a ready-made substrate to make battery separator due to superior electrolyte affinity of cellulose.Nevertheless,the direct utilization of commercial paper as a separator is im...Commercial paper is of great potential as a ready-made substrate to make battery separator due to superior electrolyte affinity of cellulose.Nevertheless,the direct utilization of commercial paper as a separator is impracticable because of its micro-sized holes between coarse cellulose fibers,which might induce short circuits.Herein,a novel reinforced composite separator is proposed by modifying commercial paper(CP)with highdielectric polymer poly(vinylidene fluoride)(PVDF)via a vacuum filtration method.The paper substrate enables excellent electrolyte wettability and high ionic conductivity of the CP-PVDF composite separator due to the superior electrolyte affinity of cellulose molecule.Meanwhile,the strong hydrogen bonds between F atoms in PVDF and H atoms in the-OH groups of cellulose endow the separator with high thermal stability and mechanical strength.Moreover,the CP-PVDF exhibits outstanding interfacial compatibility toward Li metal anode and guarantees the prominent cycle durability of symmetric Li/Li cells up to 600 h.As a result,the LiFePO_(4)/Li cells assembled with CP-PVDF separator show dramatic rate performance with high discharge capacity of 113.7 m Ah g^(-1),and prolonged cycle life at 5 C.This work indicates that the paper-based composite membranes possess great potential for high-safety and electrochemical performance batteries.展开更多
In order to improve the accuracy and efficiency of 3D model retrieval,the method based on affinity propagation clustering algorithm is proposed. Firstly,projection ray-based method is proposed to improve the feature e...In order to improve the accuracy and efficiency of 3D model retrieval,the method based on affinity propagation clustering algorithm is proposed. Firstly,projection ray-based method is proposed to improve the feature extraction efficiency of 3D models. Based on the relationship between model and its projection,the intersection in 3D space is transformed into intersection in 2D space,which reduces the number of intersection and improves the efficiency of the extraction algorithm. In feature extraction,multi-layer spheres method is analyzed. The two-layer spheres method makes the feature vector more accurate and improves retrieval precision. Secondly,Semi-supervised Affinity Propagation ( S-AP) clustering is utilized because it can be applied to different cluster structures. The S-AP algorithm is adopted to find the center models and then the center model collection is built. During retrieval process,the collection is utilized to classify the query model into corresponding model base and then the most similar model is retrieved in the model base. Finally,75 sample models from Princeton library are selected to do the experiment and then 36 models are used for retrieval test. The results validate that the proposed method outperforms the original method and the retrieval precision and recall ratios are improved effectively.展开更多
An affinity adsorbent, benzamidine Sepharose 4B, was used to separate and purify thrombin like enzymes. The p aminobenzamidine as a specific ligand was coupled to the matrix-Sepharose 4B. The recombinant thrombin like...An affinity adsorbent, benzamidine Sepharose 4B, was used to separate and purify thrombin like enzymes. The p aminobenzamidine as a specific ligand was coupled to the matrix-Sepharose 4B. The recombinant thrombin like enzyme-defibrase was used as a model in order to evaluate the efficiency of this biospecific affinity adsorbent. The homogeneity of the enzyme preparation was comfirmed as one band on sodium dodecyl sulfate polyacrylamide gel electrophoresis.展开更多
The Kazakhstanian plate was near the Tarim, Sino-Korean and South China-Southeast Asian plates in the Middle-Late Cambrian and Late Ordovician, and approached the Siberian plate in the other periods of the Early Palae...The Kazakhstanian plate was near the Tarim, Sino-Korean and South China-Southeast Asian plates in the Middle-Late Cambrian and Late Ordovician, and approached the Siberian plate in the other periods of the Early Palaeozoic. The Hi and Toksun-Yamansu terranes had been split from the Tarim plate before the Middle Devonian and then went close to Angaraland in the late Early Permian. The Beishan area on the northeastern margin of the Tarim plate came close to Angaraland first in the early Early Permian. The suturing age between the Tarim and Ka-zakhstanian-Siberian plates is generally the same as that between the Turkey-Central Iran-Gangdise and South China-Southeast Asian plates. The suturing event took place in the early Early Permian, while the corresponding tectogeny occurred between the Early and Late Permian.展开更多
The accurate equilibrium structures of S_3 and S_3^- are determined by the coupled-cluster method with single, double excitation and perturbative triple excitation(CCSD(T)) with basis sets of aug-cc-pV(n+d)Z(n = T, Q,...The accurate equilibrium structures of S_3 and S_3^- are determined by the coupled-cluster method with single, double excitation and perturbative triple excitation(CCSD(T)) with basis sets of aug-cc-pV(n+d)Z(n = T, Q, 5, or 6), complete basis set extrapolation functions with two-parameters and three-parameters, together with considering the contributions due to the core-valence electron correlation, scalar relativistic effects, spin–orbit coupling, and zero-point vibrational corrections. Our calculations show that both the neutral S_3 and anion S_3^- have open forms with C_(2r) vsymmetry. On the basis of the stable geometries, the adiabatic electron affinity of S_3 is determined to be 19041(11) cm^(-1), which is in excellent agreement with the experimental data(19059(7) cm^(-1)). The dependence of geometries and electron affinity on the computation level and physical corrections is discussed. The present computational results are helpful to the experimental molecular spectroscopy and bonding of S_3.展开更多
The parasite Plasmodium falciparum is responsible for the major world scourge malaria, a disease that affects 3.3 billion people worldwide. The development of new drugs is critical because of the diminished effectiven...The parasite Plasmodium falciparum is responsible for the major world scourge malaria, a disease that affects 3.3 billion people worldwide. The development of new drugs is critical because of the diminished effectiveness of current antimalarial agents mainly due to parasitic resistance, side effects and cost. Molecular docking was used to explore structural motifs responsible for the interactions between triose phosphate isomerase (TPI), glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and aldolase (ALD) from human and Plasmodium cells with 8 novel sufonylamide derivatives. All the ligands modeled, interact with all three enzymes in the micromolar range. The top ligand (sulfaE) shows a 70-fold increase in selective binding to pfTPI compared to hTPI (dissociation constant-KI of 7.83 μM and 0.177 μM for hTPI and pfTPI respectively), on par with antimalarial drug chloroquine.ALD and GAPDH form complexes with similar binding sites, comprising amino acids of similar chemical properties and polarities. Human TPI and pfTPI bind sulfonamide derivatives using two distinct binding sites and residues. Key residues at the dimer interface of pfTPI (VAL44, SER45, TYR48, GLN64, ASN65, VAL78) form a tight pocket with favorable polar contacts. The affinity with TPI is the most specific, stable, and selective suggesting pfTPI is a candidate for development of antimalarial drugs.展开更多
基金supported by the National Natural Science Foundation of China(62172089,61972087,62172090).
文摘Virtual machine(VM)consolidation is an effective way to improve resource utilization and reduce energy consumption in cloud data centers.Most existing studies have considered VM consolidation as a bin-packing problem,but the current schemes commonly ignore the long-term relationship between VMs and hosts.In addition,there is a lack of long-term consideration for resource optimization in the VM consolidation,which results in unnecessary VM migration and increased energy consumption.To address these limitations,a VM consolidation method based on multi-step prediction and affinity-aware technique for energy-efficient cloud data centers(MPaAF-VMC)is proposed.The proposed method uses an improved linear regression prediction algorithm to predict the next-moment resource utilization of hosts and VMs,and obtains the stage demand of resources in the future period through multi-step prediction,which is realized by iterative prediction.Then,based on the multi-step prediction,an affinity model between the VM and host is designed using the first-order correlation coefficient and Euclidean distance.During the VM consolidation,the affinity value is used to select the migration VM and placement host.The proposed method is compared with the existing consolidation algorithms on the PlanetLab and Google cluster real workload data using the CloudSim simulation platform.Experimental results show that the proposed method can achieve significant improvement in reducing energy consumption,VM migration costs,and service level agreement(SLA)violations.
基金Project supported by the National Natural Science Foundation of China(Grant No.11873013)。
文摘The formulae for parameters of a negative electron affinity semiconductor(NEAS)with large mean escape depth of secondary electrons A(NEASLD)are deduced.The methods for obtaining parameters such asλ,B,E_(pom)and the maximumδandδat 100.0 keV≥E_(po)≥1.0 keV of a NEASLD with the deduced formulae are presented(B is the probability that an internal secondary electron escapes into the vacuum upon reaching the emission surface of the emitter,δis the secondary electron yield,E_(po)is the incident energy of primary electrons and E_(pom)is the E_(po)corresponding to the maximumδ).The parameters obtained here are analyzed,and it can be concluded that several parameters of NEASLDs obtained by the methods presented here agree with those obtained by other authors.The relation between the secondary electron emission and photoemission from a NEAS with large mean escape depth of excited electrons is investigated,and it is concluded that the presented method of obtaining A is more accurate than that of obtaining the corresponding parameter for a NEAS with largeλ_(ph)(λ_(ph)being the mean escape depth of photoelectrons),and that the presented method of calculating B at E_(po)>10.0 keV is more widely applicable for obtaining the corresponding parameters for a NEAS with largeλ_(ph).
基金supported by Research Team Development Funds of L.Xue and Z.H.Ouyang,Electronic Countermeasure Institute,National University of Defense Technology。
文摘Affinity propagation(AP)is a widely used exemplar-based clustering approach with superior efficiency and clustering quality.Nevertheless,a common issue with AP clustering is the presence of excessive exemplars,which limits its ability to perform effective aggregation.This research aims to enable AP to automatically aggregate to produce fewer and more compact clusters,without changing the similarity matrix or customizing preference parameters,as done in existing enhanced approaches.An automatic aggregation enhanced affinity propagation(AAEAP)clustering algorithm is proposed,which combines a dependable partitioning clustering approach with AP to achieve this purpose.The partitioning clustering approach generates an additional set of findings with an equivalent number of clusters whenever the clustering stabilizes and the exemplars emerge.Based on these findings,mutually exclusive exemplar detection was conducted on the current AP exemplars,and a pair of unsuitable exemplars for coexistence is recommended.The recommendation is then mapped as a novel constraint,designated mutual exclusion and aggregation.To address this limitation,a modified AP clustering model is derived and the clustering is restarted,which can result in exemplar number reduction,exemplar selection adjustment,and other data point redistribution.The clustering is ultimately completed and a smaller number of clusters are obtained by repeatedly performing automatic detection and clustering until no mutually exclusive exemplars are detected.Some standard classification data sets are adopted for experiments on AAEAP and other clustering algorithms for comparison,and many internal and external clustering evaluation indexes are used to measure the clustering performance.The findings demonstrate that the AAEAP clustering algorithm demonstrates a substantial automatic aggregation impact while maintaining good clustering quality.
文摘Drug target relationship(DTR)prediction is a rapidly evolving area of research in com-putational drug discovery.Despite recent advances in computational solutions that have overcome the challenges of in vitro and in vivo experiments,most computational methods still focus on binary classification.They ignore the importance of binding affinity,which correctly distinguishes between on-targets and off-targets.In this study,we propose a deep learning model based on the microstruc-ture of compounds and proteins to predict drug-target binding affinity(DTA),which utilizes topo-logical structure information of drug molecules and sequence semantic information of proteins.In this model,graph attention network(GAT)is used to capture the deep features of the compound molecular graph,and bidirectional long short-term memory(BiLSTM)network is used to extract the protein sequence features,and the pharmacological context of DTA is obtained by combining the two.The results show that the proposed model has achieved superior performance in both cor-rectly predicting the value of interaction strength and correctly discriminating the ranking of bind-ing strength compared to the state-of-the-art baselines.A case study experiment on COVID-19 con-firms that the proposed DTA model can be used as an effective pre-screening tool in drug discovery.
文摘We describe a two-step method that uses wheat germ agglutinin immobilized on Sepharose gel followed by immunoaffinity chromatography (IAC) to extract recombinant human erythropoietin and Darbepoetin from equine plasma. Lectin affinity chromatography was shown to be an effective approach for isolating these epoetins from plasma and in combination with IAC;this method gave superior recovery when compared to the use of the latter technique alone. Moreover, due to the ease with which it can be scaled up, it is particularly well suited for pre-concentrating larger volumes of samples prior to IAC and this provides a facile way of improving the overall sensitivity with which these foreign proteins can be detected in equine plasma.
文摘Attempts were made to develop dyes with high affinity for polylactide as an alternative to the existent commercial disperse dyes. The dyes synthesized according to the affinity concept of dye to polylactide exhibited excellent dyeing properties on polylactide compared with the commercial disperse dyes.
文摘A new series of bone affinity compounds were synthesized by linking emodin with 5-fluorouracil derivatives. Their bone affinities were established by hydroxyapative (HA) affinity experiment in vitro, and their cytostatic effects were shown by the MTT assay.
基金supported by the Fundamental Research Funds for the Central Universities of Central South University(10400506021718)Hunan Provincial Science and Technology Project(2018TP1003).
文摘An affinity membrane was prepared by coaxial electrospinning and amidoxime(AONFA),and it was applied to selectively recovery Au(Ⅲ)from an aqueous solution.The static adsorption results showed that,when p H at 5,the maximum adsorption capacity of AONFA membrane for Au(Ⅲ)was 509.3 mg·g^(-1).AONFA membrane exhibit much higher affinity and selectivity towards Au(Ⅲ)than other metal cations.The membrane could be regenerated effectively by mixture solution of thiourea and HCl,and the desorption ratio reached almost 100%after 4 hours desorption.The dead-end filtration results showed that,the membrane utilization efficiency and adsorption capacity can be improved by increasing the flow rate,while increasing the concentration shorted the breakthrough process and had little impact to adsorption capacity.We can flexibly adjust the flow rate and concentration according to the situation to obtain the maximum utilization efficiency of the membrane in filtration process.The dynamic adsorption capacity is higher than the static adsorption capacity.The adsorption mechanism for Au(Ⅲ)is electrostatic adsorption and reduction.Thus,AONFA membrane filtration was demonstrated to be a promising method for continuous recover Au(Ⅲ)from wastewater.
基金financially supported by the National Natural Science Foundation of China(21863006,51662029)Key Laboratory of Jiangxi Province for Environment and Energy Catalysis(20181BCD40004)
文摘Commercial paper is of great potential as a ready-made substrate to make battery separator due to superior electrolyte affinity of cellulose.Nevertheless,the direct utilization of commercial paper as a separator is impracticable because of its micro-sized holes between coarse cellulose fibers,which might induce short circuits.Herein,a novel reinforced composite separator is proposed by modifying commercial paper(CP)with highdielectric polymer poly(vinylidene fluoride)(PVDF)via a vacuum filtration method.The paper substrate enables excellent electrolyte wettability and high ionic conductivity of the CP-PVDF composite separator due to the superior electrolyte affinity of cellulose molecule.Meanwhile,the strong hydrogen bonds between F atoms in PVDF and H atoms in the-OH groups of cellulose endow the separator with high thermal stability and mechanical strength.Moreover,the CP-PVDF exhibits outstanding interfacial compatibility toward Li metal anode and guarantees the prominent cycle durability of symmetric Li/Li cells up to 600 h.As a result,the LiFePO_(4)/Li cells assembled with CP-PVDF separator show dramatic rate performance with high discharge capacity of 113.7 m Ah g^(-1),and prolonged cycle life at 5 C.This work indicates that the paper-based composite membranes possess great potential for high-safety and electrochemical performance batteries.
基金Sponsored by the National Natural Science Foundation of China (Grant No. 51075083)
文摘In order to improve the accuracy and efficiency of 3D model retrieval,the method based on affinity propagation clustering algorithm is proposed. Firstly,projection ray-based method is proposed to improve the feature extraction efficiency of 3D models. Based on the relationship between model and its projection,the intersection in 3D space is transformed into intersection in 2D space,which reduces the number of intersection and improves the efficiency of the extraction algorithm. In feature extraction,multi-layer spheres method is analyzed. The two-layer spheres method makes the feature vector more accurate and improves retrieval precision. Secondly,Semi-supervised Affinity Propagation ( S-AP) clustering is utilized because it can be applied to different cluster structures. The S-AP algorithm is adopted to find the center models and then the center model collection is built. During retrieval process,the collection is utilized to classify the query model into corresponding model base and then the most similar model is retrieved in the model base. Finally,75 sample models from Princeton library are selected to do the experiment and then 36 models are used for retrieval test. The results validate that the proposed method outperforms the original method and the retrieval precision and recall ratios are improved effectively.
文摘An affinity adsorbent, benzamidine Sepharose 4B, was used to separate and purify thrombin like enzymes. The p aminobenzamidine as a specific ligand was coupled to the matrix-Sepharose 4B. The recombinant thrombin like enzyme-defibrase was used as a model in order to evaluate the efficiency of this biospecific affinity adsorbent. The homogeneity of the enzyme preparation was comfirmed as one band on sodium dodecyl sulfate polyacrylamide gel electrophoresis.
文摘The Kazakhstanian plate was near the Tarim, Sino-Korean and South China-Southeast Asian plates in the Middle-Late Cambrian and Late Ordovician, and approached the Siberian plate in the other periods of the Early Palaeozoic. The Hi and Toksun-Yamansu terranes had been split from the Tarim plate before the Middle Devonian and then went close to Angaraland in the late Early Permian. The Beishan area on the northeastern margin of the Tarim plate came close to Angaraland first in the early Early Permian. The suturing age between the Tarim and Ka-zakhstanian-Siberian plates is generally the same as that between the Turkey-Central Iran-Gangdise and South China-Southeast Asian plates. The suturing event took place in the early Early Permian, while the corresponding tectogeny occurred between the Early and Late Permian.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11874179,11447194,11574114,and 11874177)the Natural Science Foundation of Jilin Province,China(Grant No.20180101289JC)
文摘The accurate equilibrium structures of S_3 and S_3^- are determined by the coupled-cluster method with single, double excitation and perturbative triple excitation(CCSD(T)) with basis sets of aug-cc-pV(n+d)Z(n = T, Q, 5, or 6), complete basis set extrapolation functions with two-parameters and three-parameters, together with considering the contributions due to the core-valence electron correlation, scalar relativistic effects, spin–orbit coupling, and zero-point vibrational corrections. Our calculations show that both the neutral S_3 and anion S_3^- have open forms with C_(2r) vsymmetry. On the basis of the stable geometries, the adiabatic electron affinity of S_3 is determined to be 19041(11) cm^(-1), which is in excellent agreement with the experimental data(19059(7) cm^(-1)). The dependence of geometries and electron affinity on the computation level and physical corrections is discussed. The present computational results are helpful to the experimental molecular spectroscopy and bonding of S_3.
文摘The parasite Plasmodium falciparum is responsible for the major world scourge malaria, a disease that affects 3.3 billion people worldwide. The development of new drugs is critical because of the diminished effectiveness of current antimalarial agents mainly due to parasitic resistance, side effects and cost. Molecular docking was used to explore structural motifs responsible for the interactions between triose phosphate isomerase (TPI), glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and aldolase (ALD) from human and Plasmodium cells with 8 novel sufonylamide derivatives. All the ligands modeled, interact with all three enzymes in the micromolar range. The top ligand (sulfaE) shows a 70-fold increase in selective binding to pfTPI compared to hTPI (dissociation constant-KI of 7.83 μM and 0.177 μM for hTPI and pfTPI respectively), on par with antimalarial drug chloroquine.ALD and GAPDH form complexes with similar binding sites, comprising amino acids of similar chemical properties and polarities. Human TPI and pfTPI bind sulfonamide derivatives using two distinct binding sites and residues. Key residues at the dimer interface of pfTPI (VAL44, SER45, TYR48, GLN64, ASN65, VAL78) form a tight pocket with favorable polar contacts. The affinity with TPI is the most specific, stable, and selective suggesting pfTPI is a candidate for development of antimalarial drugs.
