Two-dimensional(2D)nanomaterials have emerged as highly efficient co-catalysts in the field of photocatalytic water splitting,due to their distinct physicochemical features.Herein,a novel 2D nanomaterial,ultrathin FeP...Two-dimensional(2D)nanomaterials have emerged as highly efficient co-catalysts in the field of photocatalytic water splitting,due to their distinct physicochemical features.Herein,a novel 2D nanomaterial,ultrathin FePS_(3)nanosheets,is prepared by an ultrasoundassisted delamination process in organic solvent,followed by the in situ construction of CdS nanosheet/FePS_(3)nanosheet hierarchical heterojunction via the solvothermal method.It is notable that the designed CdS/FePS_(3)photocatalyst demonstrates an efficient hydrogen-producing performance up to 7565μmol g^(-1)h^(-1)for hydrogen production reaction(HER)under visible-light illumination,which is almost 8 times higher than that of bulk CdS.The enhancement in HER performance is attributed to the synergy of accelerated interfacial charge transfer,high specific surface area,and extended visible-light absorption originating from as-synthesized conductive few-layer FePS_(3)nanosheets.Furthermore,the charge transfer pathway of the constructed 2D CdS/2D FePS_(3)heterojunction is unveiled by in situ atomic force microscopy with Kelvin probe force microscopy(AFM-KPFM),in situ X-ray photoelectron spectroscopy(XPS),and photoelectrochemical measurements.This study offers new insight into the rational design and controllable synthesis of FePS_(3-)based composite photocatalytic systems for efficient photocatalytic hydrogen production.展开更多
Exploring the synthesis of novel structures is crucial for the development of functional materials.In this context,a novel and intriguing 3d-5p heterometallic cluster-substituted polyoxotungstate material,H_(29)Na_(9)...Exploring the synthesis of novel structures is crucial for the development of functional materials.In this context,a novel and intriguing 3d-5p heterometallic cluster-substituted polyoxotungstate material,H_(29)Na_(9)(H_(2)O)_(21){Ca(H_(2)O)_(2)@Sb_(12)O_(18)[Ni_(2)(OH)(A-α-Si W_(10)O_(37))]_(3)}_(2)·40H_(2)O(1),was constructed using Keggintype polyoxotungstate A-α-Si W_(10)O_(37),along with Ni and Sb elements.The structure features a Tdsymmetric Sb_(12)O_(18)({Sb_(12)})cage that encapsulates an 8-coordinate Ca^(2+)ion at its face.Additionally,the{Sb_(12)}cage forms an 18-nuclear 3d-5p heterometallic cluster by connecting with three di-nuclear nickel clusters through shared oxygen atoms.Electrochemical impedance spectra studies reveal that the single crystal of 1 achieves a proton conductivity of 1.11×10^(-1)S/cm along the[110]direction and 1.04×10^(-1)S/cm along the[100]direction at 85℃ and 98%relative humidity(RH).Furthermore,the powder form of 1 exhibits a proton conductivity of 3.00×10^(-2)S/cm.These findings suggest that compound 1 holds promise as a practical proton conducting material.展开更多
Recognizing discontinuities within rock masses is a critical aspect of rock engineering.The development of remote sensing technologies has significantly enhanced the quality and quantity of the point clouds collected ...Recognizing discontinuities within rock masses is a critical aspect of rock engineering.The development of remote sensing technologies has significantly enhanced the quality and quantity of the point clouds collected from rock outcrops.In response,we propose a workflow that balances accuracy and efficiency to extract discontinuities from massive point clouds.The proposed method employs voxel filtering to downsample point clouds,constructs a point cloud topology using K-d trees,utilizes principal component analysis to calculate the point cloud normals,and employs the pointwise clustering(PWC)algorithm to extract discontinuities from rock outcrop point clouds.This method provides information on the location and orientation(dip direction and dip angle)of the discontinuities,and the modified whale optimization algorithm(MWOA)is utilized to identify major discontinuity sets and their average orientations.Performance evaluations based on three real cases demonstrate that the proposed method significantly reduces computational time costs without sacrificing accuracy.In particular,the method yields more reasonable extraction results for discontinuities with certain undulations.The presented approach offers a novel tool for efficiently extracting discontinuities from large-scale point clouds.展开更多
Objectives:Gastric cancer(GC)remains a major global health concern,and Phosphoinositide-3-Kinase Regulatory Subunit 1(PIK3R1),a regulatory subunit of the PI3K signaling pathway,may play a critical yet underexplored ro...Objectives:Gastric cancer(GC)remains a major global health concern,and Phosphoinositide-3-Kinase Regulatory Subunit 1(PIK3R1),a regulatory subunit of the PI3K signaling pathway,may play a critical yet underexplored role in GC progression.This study aimed to investigate the prognostic significance of PIK3R1 in GC and its association with the tumor immune microenvironment.Methods:PIK3R1 expression and its clinical relevance were analyzed using datasets from GC patients who underwent gastrectomy,including cohorts from The Cancer Genome Atlas(TCGA)and the Sun Yat-sen University Cancer Center(SYSUCC).Prognostic models integrating PIK3R1 expression with clinical parameters were constructed for both cohorts.The immune microenvironment associated with PIK3R1 expression was assessed through immunohistochemistry and single-cell RNA sequencing.In vitro assays were conducted to evaluate the effects of PIK3R1 on GC cell proliferation and migration.Results:PIK3R1 was significantly overexpressed in GC tissues and was closely associated with aggressive tumor characteristics and poor clinical outcomes.A nomogram combining PIK3R1 expression with clinicopathological features effectively predicted patient prognosis.Knockdown of PIK3R1 in GC cells reduced proliferation and migration in vitro.Immunological profiling revealed that high PIK3R1 expression correlated with increased infiltration of forkhead box protein P3(Foxp3^(+))and cluster of differentiation 73(CD73^(+))T cells.Patients with low PIK3R1 expression and low CD73^(+)T cell infiltration had significantly better survival.Conclusions:PIK3R1 overexpression is linked to poor prognosis in GC and influences the extent of immune cell infiltration within the tumor microenvironment.A novel prognostic model integrating PIK3R1 and CD73 expression with clinical parameters was established to stratify GC patients into distinct risk groups,offering potential value for personalized therapeutic strategies.展开更多
目的通过分析原发性卵巢肿瘤及其对应网膜转移灶的基因表达谱,识别卵巢癌转移的驱动因素,探讨其生物学功能及潜在的调控机制。方法对基因表达综合数据库(Gene Expression Omnibus,GEO)的卵巢癌与大网膜转移组织配对转录组数据集(GSE178...目的通过分析原发性卵巢肿瘤及其对应网膜转移灶的基因表达谱,识别卵巢癌转移的驱动因素,探讨其生物学功能及潜在的调控机制。方法对基因表达综合数据库(Gene Expression Omnibus,GEO)的卵巢癌与大网膜转移组织配对转录组数据集(GSE178913和GSE222982)进行差异表达分析,以筛选共有差异表达基因(differentially expressed genes,DEGs),随后进行通路富集分析。候选基因的表达模式及预后价值进一步在癌症基因组图谱(The Cancer Genome Atlas,TCGA)队列中进行评估。免疫组化验证分化簇36蛋白(cluster of differentiation 36,CD36)在配对原发灶及转移灶中的表达。通过质粒转染或慢病毒感染技术,在A2780细胞中沉默CD36,并在OVCAR-3细胞中过表达该基因。划痕和Transwell实验评估细胞迁移与侵袭能力。共表达分析、蛋白互作网络及转录因子预测结果共同表明信号转导和转录激活因子3(signal transducer and activator of transcription 3,STAT3)信号与CD36表达可能存在关联。为证实这一关联,采用STAT3抑制剂Stattic与CD36重新表达技术,在体外实验及卵巢癌腹膜转移小鼠模型中确定是否能部分挽救转移相关表型。结果卵巢癌原位灶与匹配大网膜转移灶的共有DEGs主要富集于脂质代谢相关PPAR信号通路,关键分子CD36的表达升高(P<0.05)。CD36高表达为预后不良的独立危险因素(HR=2.066,95%CI:1.414~3.035,P<0.001)。敲低CD36可抑制A2780细胞侵袭与迁移(均P<0.01),过表达CD36可促进OVCAR-3细胞侵袭与迁移(均P<0.05)。STAT3可能是CD36的上游调控因子。A2780细胞经Stattic处理后,CD36表达下调且细胞迁移和侵袭能力降低(均P<0.01),而同时过表达CD36后可逆转部分表型(均P<0.01)。体内实验显示抑制STAT3可减少小鼠腹腔转移结节和腹腔积液(均P<0.05)。结论CD36是潜在的促进卵巢癌转移的重要因子,STAT3可能参与调控CD36表达并影响转移相关表型,STAT3/CD36相关通路可能成为潜在干预靶点。展开更多
目的探讨血清基质细胞衍生因子-1(SDF-1)、单次跨膜糖蛋白147(CD147)、壳多糖酶3样蛋白1(CHI3L1)联合检测对颅内动脉粥样硬化狭窄(ICAS)患者介入术后再狭窄的预测价值。方法将2022年5月至2025年1月邢台市中心医院收治的132例ICAS患者纳...目的探讨血清基质细胞衍生因子-1(SDF-1)、单次跨膜糖蛋白147(CD147)、壳多糖酶3样蛋白1(CHI3L1)联合检测对颅内动脉粥样硬化狭窄(ICAS)患者介入术后再狭窄的预测价值。方法将2022年5月至2025年1月邢台市中心医院收治的132例ICAS患者纳入研究,所有患者均接受颅内动脉狭窄支架成形术治疗并接受持续6个月以上的随访。参照术后6个月发生颅内动脉再狭窄的情况将患者分为再狭窄组(n=25)和未狭窄组(n=107),比较两组的临床资料和血清SDF-1、CD147和CHI3L1水平,分析ICAS患者介入术后再狭窄的危险因素,并经受试者工作特征(ROC)曲线评估血清SDF-1、CD147和CHI3L1水平预测ICAS患者介入术后再狭窄的效能。结果再狭窄组的残余狭窄率和血清SDF-1、CD147与CHI3L1水平均高于未狭窄组,差异有统计学意义(P<0.05)。残余狭窄率高和血清SDF-1、CD147与CHI3L1水平升高均为ICAS患者介入术后再狭窄的危险因素(P<0.05)。ROC曲线分析表明,血清SDF-1、CD147和CHI3L1水平单独及联合预测ICAS患者介入术后再狭窄的曲线下面积(area under the curve,AUC)分别为0.810、0.770、0.859和0.927,上述指标联合预测的AUC显著高于单一指标(P<0.05)。结论血清SDF-1、CD147和CHI3L1水平升高均与ICAS患者介入术后再狭窄的发生密切相关,上述指标联合检测对此类患者介入术后再狭窄具有较高的预测效能。展开更多
A recombinant strain, Escherichia coli JM109-AN1, was obtained by constructing of a genomic library of the total DNA of Delftia sp. AN3 in E. coli JM109 and screening for catechol 2,3-dioxygenase activity. This recomb...A recombinant strain, Escherichia coli JM109-AN1, was obtained by constructing of a genomic library of the total DNA of Delftia sp. AN3 in E. coli JM109 and screening for catechol 2,3-dioxygenase activity. This recombinant strain could grow on aniline as sole carbon, nitrogen and energy source. Enzymatic assays revealed that the exogenous genes including aniline dioxygenase （AD） and catechol 2,3-dioxygenase （C230） genes could well express in the recombinant strain with the activities of AD and C230 up to 0.31 U/mg wet cell and 1.92 U/mg crude proteins, respectively. The AD or C23O of strain AN3 could only catalyze aniline or catechol but not any other substituted substrates. This recombinant strain contained a recombinant plasmid, pKC505-AN1, in which a 29.7-kb DNA fragment from Delftia sp. AN3 was inserted. Sequencing and open reading frame （orfs） analysis of this 29.7 kb fragment revealed that it contained at least 27 orfs, among them a gene cluster （consisting of at least 16 genes, named danQTA1A2BRDCEFG1HIJKG2） was responsible for the complete metabolism of aniline to TCA-cycle intermediates. This gene cluster could be divided into two main parts, the upper sequences consisted of 7 genes （danQTA1A2BRD） were predicted to encode a multi-component aniline dioxygenase and a LysR-type regulator, and the central genes （danCEFG1HIJKG2） were expected to encode meta-cleavage pathway enzymes for catechol degradation to TCA-cycle intermediates. Unlike clusters tad from Delftia tsuruhatensis AD9 and tdn from Pseudomonas putida UCC22, in this gene cluster, all the genes were in the same transcriptional direction. There was only one set of C230 gene （danC） and ferredoxin-like protein gene （danD）. The presence of only one set of these two genes and specificity of AD and C230 might be the reason for strain AN3 could only degrade aniline. The products of danQTA1A2BRDC showed 99%-100% identity to those from Delftia acidovorans 7N, and 50%-85% identity to those of tad cluster from D. tsuruhatensis AD9 in amino acid residues. Besides this dan cluster, the 29.7 kb fragment also contained genes encoding the trans-membrane transporter and transposases which might be needed for transposition of the gene cluster. Pulsed-field gel electrophoresis （PFGE） and plasmid curing experiments suggested that the dan cluster might be encoded on the chromosome of strain AN3. The GenBank accession number for the dan cluster of Delftia sp. AN3 is DQ661649.展开更多
The formation mechanism for the equilateral triangle structure of the He-3(+) cluster is proposed. The curve of the total energy versus the internuclear distance R for this structure has been calculated by the method ...The formation mechanism for the equilateral triangle structure of the He-3(+) cluster is proposed. The curve of the total energy versus the internuclear distance R for this structure has been calculated by the method of a modified arrangement channel quantum mechanics. The result shows that the curve has a minimal -7.81373 a. u at R = 1.55 a(0). The binding energy of He-3(+) with respect to He+He++He was calculated to be 0.1064 a.u. (about 2.89 eV). This means that the He-3(+) cluster may be formed in the equilateral triangle structure stably by the interaction of He+ with two helium atoms.展开更多
Pure nano-All3 and aggregates at various concentrations were prepared to examine the particle size effect of coagulation with inorganic polymer flocculant. The property and stability of various species formed were cha...Pure nano-All3 and aggregates at various concentrations were prepared to examine the particle size effect of coagulation with inorganic polymer flocculant. The property and stability of various species formed were characterized using Infrared, 27Al-NMR, photo correlation spectroscopy （PCS）, and Ferron assay. Results showed that concentration and temperature exhibited different roles on the stability of Al13. The quantity of Alb species analyzed by ferron assay in the initial aging period corresponded well with that of Al13, which has been confirmed in a dimension range of 1-2 nm by PCS. Al13 solutions at high concentrations （0.5-2.11 tool/L） were observed to undergo further aggregation with aging. The aggregates with a wide particle size distribution would contribute to the disappeared/decreased Al13 basis on the eTA1-NMR spectrum, whereas a part of Al13 would still remain as Alb. At low concentrations, All3 solution was quite stable at normal temperature, but lost its stability quickly when heating to 90~C.展开更多
基金financially supported by the Science Fund for Distinguished Young Scholars,Nanjing Forestry University(No.JC2019002)
文摘Two-dimensional(2D)nanomaterials have emerged as highly efficient co-catalysts in the field of photocatalytic water splitting,due to their distinct physicochemical features.Herein,a novel 2D nanomaterial,ultrathin FePS_(3)nanosheets,is prepared by an ultrasoundassisted delamination process in organic solvent,followed by the in situ construction of CdS nanosheet/FePS_(3)nanosheet hierarchical heterojunction via the solvothermal method.It is notable that the designed CdS/FePS_(3)photocatalyst demonstrates an efficient hydrogen-producing performance up to 7565μmol g^(-1)h^(-1)for hydrogen production reaction(HER)under visible-light illumination,which is almost 8 times higher than that of bulk CdS.The enhancement in HER performance is attributed to the synergy of accelerated interfacial charge transfer,high specific surface area,and extended visible-light absorption originating from as-synthesized conductive few-layer FePS_(3)nanosheets.Furthermore,the charge transfer pathway of the constructed 2D CdS/2D FePS_(3)heterojunction is unveiled by in situ atomic force microscopy with Kelvin probe force microscopy(AFM-KPFM),in situ X-ray photoelectron spectroscopy(XPS),and photoelectrochemical measurements.This study offers new insight into the rational design and controllable synthesis of FePS_(3-)based composite photocatalytic systems for efficient photocatalytic hydrogen production.
基金the financial support from the National Natural Science Foundation of China(Nos.22109164 and 22371046)the Key Program of the Natural Science Foundation of Fujian Province(No.2021J02007)。
文摘Exploring the synthesis of novel structures is crucial for the development of functional materials.In this context,a novel and intriguing 3d-5p heterometallic cluster-substituted polyoxotungstate material,H_(29)Na_(9)(H_(2)O)_(21){Ca(H_(2)O)_(2)@Sb_(12)O_(18)[Ni_(2)(OH)(A-α-Si W_(10)O_(37))]_(3)}_(2)·40H_(2)O(1),was constructed using Keggintype polyoxotungstate A-α-Si W_(10)O_(37),along with Ni and Sb elements.The structure features a Tdsymmetric Sb_(12)O_(18)({Sb_(12)})cage that encapsulates an 8-coordinate Ca^(2+)ion at its face.Additionally,the{Sb_(12)}cage forms an 18-nuclear 3d-5p heterometallic cluster by connecting with three di-nuclear nickel clusters through shared oxygen atoms.Electrochemical impedance spectra studies reveal that the single crystal of 1 achieves a proton conductivity of 1.11×10^(-1)S/cm along the[110]direction and 1.04×10^(-1)S/cm along the[100]direction at 85℃ and 98%relative humidity(RH).Furthermore,the powder form of 1 exhibits a proton conductivity of 3.00×10^(-2)S/cm.These findings suggest that compound 1 holds promise as a practical proton conducting material.
基金supported by the National Natural Science Foundation of China(Grant No.42407232)the Sichuan Science and Technology Program(Grant No.2024NSFSC0826).
文摘Recognizing discontinuities within rock masses is a critical aspect of rock engineering.The development of remote sensing technologies has significantly enhanced the quality and quantity of the point clouds collected from rock outcrops.In response,we propose a workflow that balances accuracy and efficiency to extract discontinuities from massive point clouds.The proposed method employs voxel filtering to downsample point clouds,constructs a point cloud topology using K-d trees,utilizes principal component analysis to calculate the point cloud normals,and employs the pointwise clustering(PWC)algorithm to extract discontinuities from rock outcrop point clouds.This method provides information on the location and orientation(dip direction and dip angle)of the discontinuities,and the modified whale optimization algorithm(MWOA)is utilized to identify major discontinuity sets and their average orientations.Performance evaluations based on three real cases demonstrate that the proposed method significantly reduces computational time costs without sacrificing accuracy.In particular,the method yields more reasonable extraction results for discontinuities with certain undulations.The presented approach offers a novel tool for efficiently extracting discontinuities from large-scale point clouds.
基金supported by the National Natural Science Foundation of China(grant no.81602426).
文摘Objectives:Gastric cancer(GC)remains a major global health concern,and Phosphoinositide-3-Kinase Regulatory Subunit 1(PIK3R1),a regulatory subunit of the PI3K signaling pathway,may play a critical yet underexplored role in GC progression.This study aimed to investigate the prognostic significance of PIK3R1 in GC and its association with the tumor immune microenvironment.Methods:PIK3R1 expression and its clinical relevance were analyzed using datasets from GC patients who underwent gastrectomy,including cohorts from The Cancer Genome Atlas(TCGA)and the Sun Yat-sen University Cancer Center(SYSUCC).Prognostic models integrating PIK3R1 expression with clinical parameters were constructed for both cohorts.The immune microenvironment associated with PIK3R1 expression was assessed through immunohistochemistry and single-cell RNA sequencing.In vitro assays were conducted to evaluate the effects of PIK3R1 on GC cell proliferation and migration.Results:PIK3R1 was significantly overexpressed in GC tissues and was closely associated with aggressive tumor characteristics and poor clinical outcomes.A nomogram combining PIK3R1 expression with clinicopathological features effectively predicted patient prognosis.Knockdown of PIK3R1 in GC cells reduced proliferation and migration in vitro.Immunological profiling revealed that high PIK3R1 expression correlated with increased infiltration of forkhead box protein P3(Foxp3^(+))and cluster of differentiation 73(CD73^(+))T cells.Patients with low PIK3R1 expression and low CD73^(+)T cell infiltration had significantly better survival.Conclusions:PIK3R1 overexpression is linked to poor prognosis in GC and influences the extent of immune cell infiltration within the tumor microenvironment.A novel prognostic model integrating PIK3R1 and CD73 expression with clinical parameters was established to stratify GC patients into distinct risk groups,offering potential value for personalized therapeutic strategies.
文摘目的通过分析原发性卵巢肿瘤及其对应网膜转移灶的基因表达谱,识别卵巢癌转移的驱动因素,探讨其生物学功能及潜在的调控机制。方法对基因表达综合数据库(Gene Expression Omnibus,GEO)的卵巢癌与大网膜转移组织配对转录组数据集(GSE178913和GSE222982)进行差异表达分析,以筛选共有差异表达基因(differentially expressed genes,DEGs),随后进行通路富集分析。候选基因的表达模式及预后价值进一步在癌症基因组图谱(The Cancer Genome Atlas,TCGA)队列中进行评估。免疫组化验证分化簇36蛋白(cluster of differentiation 36,CD36)在配对原发灶及转移灶中的表达。通过质粒转染或慢病毒感染技术,在A2780细胞中沉默CD36,并在OVCAR-3细胞中过表达该基因。划痕和Transwell实验评估细胞迁移与侵袭能力。共表达分析、蛋白互作网络及转录因子预测结果共同表明信号转导和转录激活因子3(signal transducer and activator of transcription 3,STAT3)信号与CD36表达可能存在关联。为证实这一关联,采用STAT3抑制剂Stattic与CD36重新表达技术,在体外实验及卵巢癌腹膜转移小鼠模型中确定是否能部分挽救转移相关表型。结果卵巢癌原位灶与匹配大网膜转移灶的共有DEGs主要富集于脂质代谢相关PPAR信号通路,关键分子CD36的表达升高(P<0.05)。CD36高表达为预后不良的独立危险因素(HR=2.066,95%CI:1.414~3.035,P<0.001)。敲低CD36可抑制A2780细胞侵袭与迁移(均P<0.01),过表达CD36可促进OVCAR-3细胞侵袭与迁移(均P<0.05)。STAT3可能是CD36的上游调控因子。A2780细胞经Stattic处理后,CD36表达下调且细胞迁移和侵袭能力降低(均P<0.01),而同时过表达CD36后可逆转部分表型(均P<0.01)。体内实验显示抑制STAT3可减少小鼠腹腔转移结节和腹腔积液(均P<0.05)。结论CD36是潜在的促进卵巢癌转移的重要因子,STAT3可能参与调控CD36表达并影响转移相关表型,STAT3/CD36相关通路可能成为潜在干预靶点。
文摘目的探讨血清基质细胞衍生因子-1(SDF-1)、单次跨膜糖蛋白147(CD147)、壳多糖酶3样蛋白1(CHI3L1)联合检测对颅内动脉粥样硬化狭窄(ICAS)患者介入术后再狭窄的预测价值。方法将2022年5月至2025年1月邢台市中心医院收治的132例ICAS患者纳入研究,所有患者均接受颅内动脉狭窄支架成形术治疗并接受持续6个月以上的随访。参照术后6个月发生颅内动脉再狭窄的情况将患者分为再狭窄组(n=25)和未狭窄组(n=107),比较两组的临床资料和血清SDF-1、CD147和CHI3L1水平,分析ICAS患者介入术后再狭窄的危险因素,并经受试者工作特征(ROC)曲线评估血清SDF-1、CD147和CHI3L1水平预测ICAS患者介入术后再狭窄的效能。结果再狭窄组的残余狭窄率和血清SDF-1、CD147与CHI3L1水平均高于未狭窄组,差异有统计学意义(P<0.05)。残余狭窄率高和血清SDF-1、CD147与CHI3L1水平升高均为ICAS患者介入术后再狭窄的危险因素(P<0.05)。ROC曲线分析表明,血清SDF-1、CD147和CHI3L1水平单独及联合预测ICAS患者介入术后再狭窄的曲线下面积(area under the curve,AUC)分别为0.810、0.770、0.859和0.927,上述指标联合预测的AUC显著高于单一指标(P<0.05)。结论血清SDF-1、CD147和CHI3L1水平升高均与ICAS患者介入术后再狭窄的发生密切相关,上述指标联合检测对此类患者介入术后再狭窄具有较高的预测效能。
文摘A recombinant strain, Escherichia coli JM109-AN1, was obtained by constructing of a genomic library of the total DNA of Delftia sp. AN3 in E. coli JM109 and screening for catechol 2,3-dioxygenase activity. This recombinant strain could grow on aniline as sole carbon, nitrogen and energy source. Enzymatic assays revealed that the exogenous genes including aniline dioxygenase （AD） and catechol 2,3-dioxygenase （C230） genes could well express in the recombinant strain with the activities of AD and C230 up to 0.31 U/mg wet cell and 1.92 U/mg crude proteins, respectively. The AD or C23O of strain AN3 could only catalyze aniline or catechol but not any other substituted substrates. This recombinant strain contained a recombinant plasmid, pKC505-AN1, in which a 29.7-kb DNA fragment from Delftia sp. AN3 was inserted. Sequencing and open reading frame （orfs） analysis of this 29.7 kb fragment revealed that it contained at least 27 orfs, among them a gene cluster （consisting of at least 16 genes, named danQTA1A2BRDCEFG1HIJKG2） was responsible for the complete metabolism of aniline to TCA-cycle intermediates. This gene cluster could be divided into two main parts, the upper sequences consisted of 7 genes （danQTA1A2BRD） were predicted to encode a multi-component aniline dioxygenase and a LysR-type regulator, and the central genes （danCEFG1HIJKG2） were expected to encode meta-cleavage pathway enzymes for catechol degradation to TCA-cycle intermediates. Unlike clusters tad from Delftia tsuruhatensis AD9 and tdn from Pseudomonas putida UCC22, in this gene cluster, all the genes were in the same transcriptional direction. There was only one set of C230 gene （danC） and ferredoxin-like protein gene （danD）. The presence of only one set of these two genes and specificity of AD and C230 might be the reason for strain AN3 could only degrade aniline. The products of danQTA1A2BRDC showed 99%-100% identity to those from Delftia acidovorans 7N, and 50%-85% identity to those of tad cluster from D. tsuruhatensis AD9 in amino acid residues. Besides this dan cluster, the 29.7 kb fragment also contained genes encoding the trans-membrane transporter and transposases which might be needed for transposition of the gene cluster. Pulsed-field gel electrophoresis （PFGE） and plasmid curing experiments suggested that the dan cluster might be encoded on the chromosome of strain AN3. The GenBank accession number for the dan cluster of Delftia sp. AN3 is DQ661649.
文摘The formation mechanism for the equilateral triangle structure of the He-3(+) cluster is proposed. The curve of the total energy versus the internuclear distance R for this structure has been calculated by the method of a modified arrangement channel quantum mechanics. The result shows that the curve has a minimal -7.81373 a. u at R = 1.55 a(0). The binding energy of He-3(+) with respect to He+He++He was calculated to be 0.1064 a.u. (about 2.89 eV). This means that the He-3(+) cluster may be formed in the equilateral triangle structure stably by the interaction of He+ with two helium atoms.
基金supported by the National Natural Science Foundation of China (No. 51025830, 50921064)the National Hi-Tech Research and Development Program(863) of China (No. 2008AA06A414)
文摘Pure nano-All3 and aggregates at various concentrations were prepared to examine the particle size effect of coagulation with inorganic polymer flocculant. The property and stability of various species formed were characterized using Infrared, 27Al-NMR, photo correlation spectroscopy （PCS）, and Ferron assay. Results showed that concentration and temperature exhibited different roles on the stability of Al13. The quantity of Alb species analyzed by ferron assay in the initial aging period corresponded well with that of Al13, which has been confirmed in a dimension range of 1-2 nm by PCS. Al13 solutions at high concentrations （0.5-2.11 tool/L） were observed to undergo further aggregation with aging. The aggregates with a wide particle size distribution would contribute to the disappeared/decreased Al13 basis on the eTA1-NMR spectrum, whereas a part of Al13 would still remain as Alb. At low concentrations, All3 solution was quite stable at normal temperature, but lost its stability quickly when heating to 90~C.
