Objective: The purposes of this study were to assess the efficacy of allogeneic hematopoietic stem cell transplantation (HSCT) for acute leukemia (AL) and analyze the factors affecting the prognosis of these pati...Objective: The purposes of this study were to assess the efficacy of allogeneic hematopoietic stem cell transplantation (HSCT) for acute leukemia (AL) and analyze the factors affecting the prognosis of these patients. Methods: The clinical and follow-up data of 93 AL patients (median age, 30 years) undergoing allogeneic HSCT in Xiangya Hospital over the past 12 years were collected, and the potential factors affecting the efficacy and prognosis of allogeneic HSCT patients were determined. Results: Hematopoietic reconstitution was achieved in 90 patients. At the last follow-up, the incidences of severe acute graft versus host disease (aGvHD) and extensive chronic GvHD (cGvHD) were 14.0% and 20.0%, the 3-year cumulative incidence of transplantation related mortality (TRM) and relapse rate were 16.8%±6.1% and 21.3%±6.7%, and the estimated 3-year overall survival (OS) and disease-free survival (DFS) of the patients were 64.6%±5.4% and 56.5%±5.5%, respectively. Univariate analysis indicated that age older than 40 years, HLA mismatch, and severe lung infection within the first 100 days after transplantation were risk factors for severe aGvHD, age older than 40 years, HLA mismatch, severe lung infection within the first 100 days after transplantation, and severe aGvHD were risk factors for TRM, high-risk AL and lack of cGvHD were risk factors for relapse (all P〈0.05). Survival estimation showed that HLA mismatch, severe lung infection occurring within the first 100 days post-transplantation, high-risk AL severe aGvHD and lack of cGvHD were risk factors associated with poor prognosis (all P〈0.05). Further multivariate analyses revealed that severe lung infection within the first 100 days post-transplantation, severe aGvHD and lack of cGvHD were independent risk factors for unfavorable outcomes (all P〈0.05). Conclusions: Allogeneic HSCT can improve the DFS of AL patients, and severe lung infection within the first 100 days post-transplantation, severe aGvHD and lack of cGvHD are independent risk factors affecting the prognosis.展开更多
The performance of traditional vibration based fault diagnosis methods greatly depends on those hand- crafted features extracted using signal processing algo- rithms, which require significant amounts of domain knowle...The performance of traditional vibration based fault diagnosis methods greatly depends on those hand- crafted features extracted using signal processing algo- rithms, which require significant amounts of domain knowledge and human labor, and do not generalize well to new diagnosis domains. Recently, unsupervised represen- tation learning provides an alternative promising solution to feature extraction in traditional fault diagnosis due to its superior learning ability from unlabeled data. Given that vibration signals usually contain multiple temporal struc- tures, this paper proposes a multiscale representation learning (MSRL) framework to learn useful features directly from raw vibration signals, with the aim to capture rich and complementary fault pattern information at dif- ferent scales. In our proposed approach, a coarse-grained procedure is first employed to obtain multiple scale signals from an original vibration signal. Then, sparse filtering, a newly developed unsupervised learning algorithm, is applied to automatically learn useful features from each scale signal, respectively, and then the learned features at each scale to be concatenated one by one to obtain multi- scale representations. Finally, the multiscale representa- tions are fed into a supervised classifier to achieve diagnosis results. Our proposed approach is evaluated using two different case studies: motor bearing and wind turbine gearbox fault diagnosis. Experimental results show that the proposed MSRL approach can take full advantages of the availability of unlabeled data to learn discriminative features and achieved better performance with higher accuracy and stability compared to the traditional approaches.展开更多
Birt–Hogg–Dubé(BHD) syndrome, a hereditary renal cancer syndrome caused by mutations in the folliculin(FLCN) gene, is characterized by the presence of ibrofolliculomas, pulmonary cysts, spontaneous pneumothorax...Birt–Hogg–Dubé(BHD) syndrome, a hereditary renal cancer syndrome caused by mutations in the folliculin(FLCN) gene, is characterized by the presence of ibrofolliculomas, pulmonary cysts, spontaneous pneumothorax, and renal cell carcinoma(RCC). Few BHD syndrome cases have been reported in Asian countries, and cutaneous presentations are relatively rare in Asian patients. Asian BHD patients may be misdiagnosed due to their atypical manifestations. Here, we report two Chinese BHD patients with novel FLCN mutations(c.946-947 del AG in exon 9 and c.770-772 del CCT in exon 7). Both of them had RCC and spontaneous pneumothorax without ibrofolliculomas. In patients with RCC and pulmonary cysts but without cutaneous lesions, screening for mutations in the FLCN gene should be performed, especially for those with a family history of RCC or pulmonary cysts(pneumothorax).展开更多
In this paper, minimal submanifolds in Finsler spaces with (α, β)-metrics are studied. Especially, helicoids are also minimal in (α, β)-Minkowski spaces. Then the minimal surfaces of conoid in Finsler spaces with ...In this paper, minimal submanifolds in Finsler spaces with (α, β)-metrics are studied. Especially, helicoids are also minimal in (α, β)-Minkowski spaces. Then the minimal surfaces of conoid in Finsler spaces with (α, β)-metrics are given. Last, the Gauss curvature of the conoid in the 3-dimension Randers-Minkowski space is studied.展开更多
Herein, we report a bottom-up solvothermal route to synthesize a flexible, highly efficient MoS2@SWNT electrocatalyst for hydrogen evolution reactions (HER). Characterization revealed that branchqike MoS2 nanosheets...Herein, we report a bottom-up solvothermal route to synthesize a flexible, highly efficient MoS2@SWNT electrocatalyst for hydrogen evolution reactions (HER). Characterization revealed that branchqike MoS2 nanosheets containing sulfur- rich sites were in situ uniformly dispersed on free-standing single-walled carbon nanotube (SWNT) film, which could expose more unsaturated sulfur atoms, allowing excellent electrical contact with active sites. The flexible catalyst exhibited excellent HER performance with a low overpotential (-150 mV at 10 ma/cm2) and small Tafel slope (4l mV/dec). To further explain the improved performance, the local electronic structure was investigated by X-ray absorption near-edge structure (XANES) analysis, proving the presence of unsaturated sulfur atoms and strong electronic coupling between MoS2 and SWNT. This study provides an in-situ synthetic route to create new multifunctional flexible hybridized catalysts and useful insights into the relationships electronic structure, and properties among the catalyst microstructure,展开更多
In this study, we present the preparation of stable 1T-WS2 ultrathin nanosheets with NH~ intercalation using a bottom-up hydrothermal method and the potential application of this material in light-induced photothermal...In this study, we present the preparation of stable 1T-WS2 ultrathin nanosheets with NH~ intercalation using a bottom-up hydrothermal method and the potential application of this material in light-induced photothermal cancer therapy. Our results revealed that nanosheets with a size of 150 nm were highly hydrophilic and exhibited strong light absorption and excellent photostability in the broad near-infrared wavelength region. The in vitro experimental results indicated good biocompatibility of the nanosheets. More notably, our in vivo antitumor experiments illustrated that light-induced photothermal ablation originating from irradiation of the 1T-WS2 nanosheets with an 808 nm laser could efficiently kill tumor cells; these effects were obtained not only at the cellular level but also in the living organs of mice. This result may lead to new applications of two-dimensional layered materials in novel photothermal therapies and other photothermal related fields.展开更多
In most cases, layered transition metal dichalcogenides (LTMDs), containing metallic phases, show electrochemical behavior different from their semiconductor counterparts. Typically, two-dimensional layered metallic...In most cases, layered transition metal dichalcogenides (LTMDs), containing metallic phases, show electrochemical behavior different from their semiconductor counterparts. Typically, two-dimensional layered metallic 1T-MoS2 demonstrates better electrocatalytic performance for water splitting compared to its 2H counterpart. However, the characteristics of low metallic phase concentration and poor stability limit its applications in some cases. Herein, we demonstrate a simple and efficient bottom-up wet-chemistry strategy for the large-scale synthesis of nanoscopic ultrathin Mo1-xWxS2 nanosheets with enlarged interlayer spacing and high metallic phase concentration. Our characterizations, including X-ray absorption fine structure spectroscopy (XAFS), high-angle annular dark-field- scanning transmission electron microscopy (HAADF-STEM), and X-ray photoelectron spectroscopy (XPS) revealed that the metallic ultrathin ternary Mo1-xWxS2 nanosheets exhibited distorted metal-metal bonds and a tunable metallic phase concentration. As a proof of concept, this optimized catalyst, with the highest metallic phase concentration (greater than 90%), achieved a low overpotential of about -155 mV at a current density of -10 ma/cm^2, a small Tafel slope of 67 mV/dec, and an increased turnover frequency (TOF) of 1.3 H2 per second at an overpotential of -300 mV (vs. reversible hydrogen electrode (RHE)), highlighting the importance of the metallic phase. More importantly, this study can lead to a facile solvothermal route to prepare stable and high-metallic- phase-concentration transition-metal-based two-dimensional materials for future applications.展开更多
We have sought to improve the electrocatalytic performance of tungsten nitride through synthetic control over chemical composition and morphology.In particular,we have generated a thermodynamically unstable but cataly...We have sought to improve the electrocatalytic performance of tungsten nitride through synthetic control over chemical composition and morphology.In particular,we have generated a thermodynamically unstable but catalytically promising nitrogen-rich phase of tungsten via a hydrothermal generation of a tungsten oxide intermediate and subsequent annealing in ammonia.The net product consisted of three-dimensional(3D)micron-scale flower-like motifs of W2N3;this architecture not only evinced high structural stability but also incorporated the favorable properties of constituent two-dimensional nanosheets.From a performance perspective,as-prepared 3D W2N3 demonstrated promising hydrogen evolution reaction(HER)activities,especially in an acidic environment with a measured overpotential value of−101 mV at a current density of 10 mA/cm^2.To further enhance the electrocatalytic activity,small amounts of precious metal nanoparticles(such as Pt and Au),consisting of variable sizes,were uniformly deposited onto the underlying 3D W2N3 motifs using a facile direct deposition method;these composites were applied towards the CO2 reduction reaction(CO2RR).A highlight of this series of experiments was that Au/W2N3 composites were found to be a much more active HER(as opposed to either a CO2RR or a methanol oxidation reaction(MOR))catalyst.展开更多
With regard to the reaction of higheralcohol synthesis(HAS),the optimizations of activity and selectivity towards C_(2+)alcohol are restricted by the improper equilibrium in two different CO activation pathways and ch...With regard to the reaction of higheralcohol synthesis(HAS),the optimizations of activity and selectivity towards C_(2+)alcohol are restricted by the improper equilibrium in two different CO activation pathways and chain growth capacity.Herein,we find that delibrately controlling the compositions of catalysts is an effective strategy to achieve the equilibrium of CO activation pathways and promote the chain growth.As a result,the optimized Cu_(0.25)Co_(0.75) alloy catalyst can achieve a large proportion of higher alcohol in alcohol products(C_(2+)OH/MeOH=4.40),together with high CO conversion of 71.27%and space-time-yield of 147.65 g kg^(-1) h^(-1).The mechanistic studies suggest that the good performance of Cu_(0.25)Co_(0.75) catalyst is attributed to the synergistic effect between alloyed Cu and Co.展开更多
Cheng-type inequality, Cheeger-type inequality and Faber-Krahn-type inequality are generalized to Finsler manifolds. For a compact Finsler manifold with the weighted Ricci curvature bounded from below by a negative co...Cheng-type inequality, Cheeger-type inequality and Faber-Krahn-type inequality are generalized to Finsler manifolds. For a compact Finsler manifold with the weighted Ricci curvature bounded from below by a negative constant, Li-Yau's estimation of the first eigenvalue is also given.展开更多
Studying the geometric flow plays a powerful role in mathematics and physics. In this paper, we introduce the mean curvature flow on Finsler manifolds and give a number of examples of the mean curvature flow. For Mink...Studying the geometric flow plays a powerful role in mathematics and physics. In this paper, we introduce the mean curvature flow on Finsler manifolds and give a number of examples of the mean curvature flow. For Minkowski spaces, a special case of Finsler manifolds, we prove the short time existence and uniqueness for solutions of the mean curvature flow and prove that the flow preserves the convexity and mean convexity.We also derive some comparison principles for the mean curvature flow.展开更多
Auxin is unique among plant hormones in that its function requires polarized transport across plant cells.A chemiosmotic model was proposed to explain how polar auxin transport is derived by the H^(+)gradient across t...Auxin is unique among plant hormones in that its function requires polarized transport across plant cells.A chemiosmotic model was proposed to explain how polar auxin transport is derived by the H^(+)gradient across the plasma membrane(PM)established by PM H^(+)-adenosine triphosphatases(ATPases).However,a classical genetic approach by mutations in PM H^(+)-ATPase members did not result in the ablation of polar auxin distribution,possibly due to functional redundancy in this gene family.To confirm the crucial role of PM H^(+)-ATPases in the polar auxin transport model,we employed a chemical genetic approach.Through a chemical screen,we identified protonstatin-1(PS-1),a selective small-molecule inhibitor of PM H^(+)-ATPase activity that inhibits auxin transport.Assays with transgenic plants and yeast strains showed that the activity of PM H^(+)-ATPases affects auxin uptake as well as acropetal and basipetal polar auxin transport.We propose that PS-1 can be used as a tool to interrogate the function of PM H^(+)-ATPases.Our results support the chemiosmotic model in which PM H^(+)-ATPase itself plays a fundamental role in polar auxin transport.展开更多
Background: The effect and mechanism of Saccharomyces boulardii (Sb) in inflammatory bowel disease are unclear. The objective of the study was to evaluate the impact of Sb on intestinal mucosal barrier and intestinal ...Background: The effect and mechanism of Saccharomyces boulardii (Sb) in inflammatory bowel disease are unclear. The objective of the study was to evaluate the impact of Sb on intestinal mucosal barrier and intestinal flora in a colitis mouse model. Methods: Forty C57BL/6J male mice were randomly assigned to five groups: normal control group (A), pathologic control group (B), Sb treatment group (C), mesalazine treatment group (D), and Sb combined with mesalazine treatment group (E). Colitis was induced by the addition of 2.5%(wt/vol) dextran sodium sulfate (DSS) in the drinking water ad libitum for 7 days. The general condition, weight change, stool property, and bloody stool level of mice were observed to evaluate the disease activity index. The expression of zona occludens-1 (ZO-1) and occludin in intestinal tissue were measured by immunohistochemistry. The level of tumor necrosis factor-α(TNF-α) and interleukin (IL)-8 in plasma was measured by enzyme linked immunosorbent assay. Inter-cellular tight junctions were observed by transmission electron microscopy. The feces and intestinal contents were collected sterilely, and intestinal flora was analyzed by 16S rRNA sequencing. Results: Compared with group B, Sb reduced the disease activity index and histological score of group C (disease activity index: group B 2.708 ± 0.628, group C 1.542 ± 0.616, PBC = 0.005;histological score: group B 9.875 ± 3.271, group C 4.750 ± 1.832, PBC = 0.005) in DSS-induced colitis in mice. Sb exerted a protect effect on the expression of ZO-1 (group B 2.075 ± 1.176, group C 4.225 ± 1.316, PBC = 0.019) and occludin (group B 2.200 ± 0.968, group C 3.525 ± 1.047, PBC = 0.023). Compared with group B, Sb decreased the level of TNF-α and IL-8 of group C (TNF-α: group B 716.323 ± 44.691 ng/L, group C 521.740 ± 90.121 ng/L, PBC = 0.001;IL-8: group B 128.992 ± 11.475 pg/mL, group C 106.283 ± 15.906 pg/mL, PBC = 0.012). Treatment with Sb preserved the tight junctions and ameliorated microvilli and inter-cellular space. Treatment with Sb also showed its own characteristics: a higher percentage of Bacteroidetes and a lower percentage of Firmicutes, with significant differences or a significant trend. The proportion of the S24-7 family was increased significantly in the Sb treatment group. Conclusions: Sb shows an anti-inflammatory effect and has a protective effect on the intestinal mucosal mechanical barrier. Sb may up-regulate the abundance of family S24-7 specifically, and maybe a mechanism underlying its function.展开更多
In this paper,we give the complete classifications of isoparametric hypersurfaces in Randers space forms.By studying the principal curvatures of anisotropic submanifolds in a Randers space(N,F)with the navigation data...In this paper,we give the complete classifications of isoparametric hypersurfaces in Randers space forms.By studying the principal curvatures of anisotropic submanifolds in a Randers space(N,F)with the navigation data(h,W),we find that a Randers space form(N,F,dμBH)and the corresponding Riemannian space(N,h)have the same isoparametric hypersurfaces,but in general,their isoparametric functions are different.We give a necessary and sufficient condition for an isoparametric function of(N,h)to be isoparametric on(N,F,dμBH),from which we get some examples of isoparametric functions.展开更多
Rational design and facet-engineering of nanocrystal is an effective strategy to optimize the catalytic performance of abundant and economic semiconductorbased photocatalysts.In this study,we demonstrate a novel terna...Rational design and facet-engineering of nanocrystal is an effective strategy to optimize the catalytic performance of abundant and economic semiconductorbased photocatalysts.In this study,we demonstrate a novel ternary Cu2MoS4 nanotube with the {010} facet exposed,synthesized via a hydrothermal method.Compared with two-dimensional Cu2MoS4 nanosheet with the {001} facet exposed,this one-dimensional nanotube exhibits highly enhanced performance of photodegradation and water splitting.Both theoretical calculations and experimental results suggest that the conduction band minimum (CBM) of the {010} facet crystal shows lower potential than that of the {001} facet.In particular,the up-shifted CBM in Cu2MoS4 nanotube is significantly beneficial for the absorption of dye molecules and reduction of H+ to H2.These results may open a new route for realizing high-efficiency photocatalysts based on Cu2MX4 by facet engineering.展开更多
In this paper, we study isoparametric hypersurfaces in Finsler space forms by investigating focal points, tubes and parallel hypersurfaces of submanifolds. We prove that the focal submanifolds of isoparametric hypersu...In this paper, we study isoparametric hypersurfaces in Finsler space forms by investigating focal points, tubes and parallel hypersurfaces of submanifolds. We prove that the focal submanifolds of isoparametric hypersurfaces are anisotropic-minimal and obtain a general Cartan-type formula in a Finsler space form with vanishing reversible torsion, from which we give some classifications on the number of distinct principal curvatures or their multiplicities.展开更多
To achieve a complete industrial chain of hydrogen energy,the development of efficient electrocatalysts for hydrogen evolution reaction(HER)is of great concerns.Herein,a nickel nitride supported platinum(Pt)catalyst w...To achieve a complete industrial chain of hydrogen energy,the development of efficient electrocatalysts for hydrogen evolution reaction(HER)is of great concerns.Herein,a nickel nitride supported platinum(Pt)catalyst with highly exposed Pt(110)facets(Pt_((110))-Ni_(3)N)is obtained for catalyzing HER.Combined X-ray spectra and density functional theory studies demonstrate that the interfacial electronic interaction between Pt and Ni3N support can promote the hydrogen evolution on Pt(110)facets by weakening hydrogen adsorption.As a result,the Pt_((110))-Ni_(3)N catalyst delivers an obviously higher specific activity than commercial 20 wt.%Pt/C in acidic media.This work suggests that the suitable interface modulation may play a vital role in rationally designing advanced electrocatalysts.展开更多
文摘Objective: The purposes of this study were to assess the efficacy of allogeneic hematopoietic stem cell transplantation (HSCT) for acute leukemia (AL) and analyze the factors affecting the prognosis of these patients. Methods: The clinical and follow-up data of 93 AL patients (median age, 30 years) undergoing allogeneic HSCT in Xiangya Hospital over the past 12 years were collected, and the potential factors affecting the efficacy and prognosis of allogeneic HSCT patients were determined. Results: Hematopoietic reconstitution was achieved in 90 patients. At the last follow-up, the incidences of severe acute graft versus host disease (aGvHD) and extensive chronic GvHD (cGvHD) were 14.0% and 20.0%, the 3-year cumulative incidence of transplantation related mortality (TRM) and relapse rate were 16.8%±6.1% and 21.3%±6.7%, and the estimated 3-year overall survival (OS) and disease-free survival (DFS) of the patients were 64.6%±5.4% and 56.5%±5.5%, respectively. Univariate analysis indicated that age older than 40 years, HLA mismatch, and severe lung infection within the first 100 days after transplantation were risk factors for severe aGvHD, age older than 40 years, HLA mismatch, severe lung infection within the first 100 days after transplantation, and severe aGvHD were risk factors for TRM, high-risk AL and lack of cGvHD were risk factors for relapse (all P〈0.05). Survival estimation showed that HLA mismatch, severe lung infection occurring within the first 100 days post-transplantation, high-risk AL severe aGvHD and lack of cGvHD were risk factors associated with poor prognosis (all P〈0.05). Further multivariate analyses revealed that severe lung infection within the first 100 days post-transplantation, severe aGvHD and lack of cGvHD were independent risk factors for unfavorable outcomes (all P〈0.05). Conclusions: Allogeneic HSCT can improve the DFS of AL patients, and severe lung infection within the first 100 days post-transplantation, severe aGvHD and lack of cGvHD are independent risk factors affecting the prognosis.
基金Supported by Hebei Provincial Natural Science Foundation of China(Grant No.F2016203421)
文摘The performance of traditional vibration based fault diagnosis methods greatly depends on those hand- crafted features extracted using signal processing algo- rithms, which require significant amounts of domain knowledge and human labor, and do not generalize well to new diagnosis domains. Recently, unsupervised represen- tation learning provides an alternative promising solution to feature extraction in traditional fault diagnosis due to its superior learning ability from unlabeled data. Given that vibration signals usually contain multiple temporal struc- tures, this paper proposes a multiscale representation learning (MSRL) framework to learn useful features directly from raw vibration signals, with the aim to capture rich and complementary fault pattern information at dif- ferent scales. In our proposed approach, a coarse-grained procedure is first employed to obtain multiple scale signals from an original vibration signal. Then, sparse filtering, a newly developed unsupervised learning algorithm, is applied to automatically learn useful features from each scale signal, respectively, and then the learned features at each scale to be concatenated one by one to obtain multi- scale representations. Finally, the multiscale representa- tions are fed into a supervised classifier to achieve diagnosis results. Our proposed approach is evaluated using two different case studies: motor bearing and wind turbine gearbox fault diagnosis. Experimental results show that the proposed MSRL approach can take full advantages of the availability of unlabeled data to learn discriminative features and achieved better performance with higher accuracy and stability compared to the traditional approaches.
基金supported by the National Natural Science Foundation of China(Grant Number:81172418)the Beijing Municipal Natural Science Foundation(Grant Number:7142160)
文摘Birt–Hogg–Dubé(BHD) syndrome, a hereditary renal cancer syndrome caused by mutations in the folliculin(FLCN) gene, is characterized by the presence of ibrofolliculomas, pulmonary cysts, spontaneous pneumothorax, and renal cell carcinoma(RCC). Few BHD syndrome cases have been reported in Asian countries, and cutaneous presentations are relatively rare in Asian patients. Asian BHD patients may be misdiagnosed due to their atypical manifestations. Here, we report two Chinese BHD patients with novel FLCN mutations(c.946-947 del AG in exon 9 and c.770-772 del CCT in exon 7). Both of them had RCC and spontaneous pneumothorax without ibrofolliculomas. In patients with RCC and pulmonary cysts but without cutaneous lesions, screening for mutations in the FLCN gene should be performed, especially for those with a family history of RCC or pulmonary cysts(pneumothorax).
文摘In this paper, minimal submanifolds in Finsler spaces with (α, β)-metrics are studied. Especially, helicoids are also minimal in (α, β)-Minkowski spaces. Then the minimal surfaces of conoid in Finsler spaces with (α, β)-metrics are given. Last, the Gauss curvature of the conoid in the 3-dimension Randers-Minkowski space is studied.
基金We acknowledge the financial support of the National Basic Research Program of China (No. 2014CB848900), the National Natural Science Foundation of China (Nos. U1232131, U1532112, 11375198, and 11574280), the Fundamental Research Funds for the Central Universities (No. WK2310000053), User with Potential from CAS Hefei Science Center (No. 2015HSC-UP020) and Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education) Nankai University. L. S. thanks the recruitment program of global experts, the CAS Hundred Talent Program. We also thank the Shanghai synchrotron Radiation Facility (14W1, SSRF), the Beijing Synchrotron Radiation Facility (1W1B and soft-X-ray endstation, BSRF) and the Hefei Synchrotron Radiation Facility (MCD and Photoemission Endstations, NSRL) for help in characterizations.
文摘Herein, we report a bottom-up solvothermal route to synthesize a flexible, highly efficient MoS2@SWNT electrocatalyst for hydrogen evolution reactions (HER). Characterization revealed that branchqike MoS2 nanosheets containing sulfur- rich sites were in situ uniformly dispersed on free-standing single-walled carbon nanotube (SWNT) film, which could expose more unsaturated sulfur atoms, allowing excellent electrical contact with active sites. The flexible catalyst exhibited excellent HER performance with a low overpotential (-150 mV at 10 ma/cm2) and small Tafel slope (4l mV/dec). To further explain the improved performance, the local electronic structure was investigated by X-ray absorption near-edge structure (XANES) analysis, proving the presence of unsaturated sulfur atoms and strong electronic coupling between MoS2 and SWNT. This study provides an in-situ synthetic route to create new multifunctional flexible hybridized catalysts and useful insights into the relationships electronic structure, and properties among the catalyst microstructure,
文摘In this study, we present the preparation of stable 1T-WS2 ultrathin nanosheets with NH~ intercalation using a bottom-up hydrothermal method and the potential application of this material in light-induced photothermal cancer therapy. Our results revealed that nanosheets with a size of 150 nm were highly hydrophilic and exhibited strong light absorption and excellent photostability in the broad near-infrared wavelength region. The in vitro experimental results indicated good biocompatibility of the nanosheets. More notably, our in vivo antitumor experiments illustrated that light-induced photothermal ablation originating from irradiation of the 1T-WS2 nanosheets with an 808 nm laser could efficiently kill tumor cells; these effects were obtained not only at the cellular level but also in the living organs of mice. This result may lead to new applications of two-dimensional layered materials in novel photothermal therapies and other photothermal related fields.
基金We acknowledge the financial support of the National Basic Research Program of China (Nos. 2014CB848900 and 2016YFA0200602), the National Natural Science Foundation of China (Nos. U1532112, 11375198, 11574280, and 21573204), CUSF (No. WK2310000053) and funds from Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education). L. S. thanks the recruitment program of global experts, the CAS Hundred Talent Program. We also thank the Shanghai synchrotron Radiation Facility (14W1, SSRF), the Beijing Synchrotron Radiation Facility (1W1B and soft-X-ray endstation, BSRF), the Hefei Synchrotron Radiation Facility (MCD and Photoemission Endstations, NSRL) and USTC Center for Micro and Nanoscale Research and Fabrication.
文摘In most cases, layered transition metal dichalcogenides (LTMDs), containing metallic phases, show electrochemical behavior different from their semiconductor counterparts. Typically, two-dimensional layered metallic 1T-MoS2 demonstrates better electrocatalytic performance for water splitting compared to its 2H counterpart. However, the characteristics of low metallic phase concentration and poor stability limit its applications in some cases. Herein, we demonstrate a simple and efficient bottom-up wet-chemistry strategy for the large-scale synthesis of nanoscopic ultrathin Mo1-xWxS2 nanosheets with enlarged interlayer spacing and high metallic phase concentration. Our characterizations, including X-ray absorption fine structure spectroscopy (XAFS), high-angle annular dark-field- scanning transmission electron microscopy (HAADF-STEM), and X-ray photoelectron spectroscopy (XPS) revealed that the metallic ultrathin ternary Mo1-xWxS2 nanosheets exhibited distorted metal-metal bonds and a tunable metallic phase concentration. As a proof of concept, this optimized catalyst, with the highest metallic phase concentration (greater than 90%), achieved a low overpotential of about -155 mV at a current density of -10 ma/cm^2, a small Tafel slope of 67 mV/dec, and an increased turnover frequency (TOF) of 1.3 H2 per second at an overpotential of -300 mV (vs. reversible hydrogen electrode (RHE)), highlighting the importance of the metallic phase. More importantly, this study can lead to a facile solvothermal route to prepare stable and high-metallic- phase-concentration transition-metal-based two-dimensional materials for future applications.
基金This material is based on work performed in SSWs laboratory,supported by the U.S.National Science Foundation under Grant No.CHE-1807640.Structural characterization experiments(TEM,SEM,and XPS)for this manuscript were performed in part at the Center for Functional Nanomaterials,located at Brookhaven National Laboratory,which is supported by the U.S.Department of Energy under Contract No.DE-SC-00112704.Authors from Columbia University acknowledge support from the U.S.Department of Energy,Office of Science,Catalysis Science Program(No.DE-FG02-13ER16381).B.M.T.acknowledges support from the U.S.Department of Energy,Office of Science,Office of Workforce Development for Teachers and Scientists,Office of Science Graduate Student Research(SCGSR)program.The SCGSR program is administered by the Oak Ridge Institute for Science and Education for the DOE under contract number DE-SC0014664.
文摘We have sought to improve the electrocatalytic performance of tungsten nitride through synthetic control over chemical composition and morphology.In particular,we have generated a thermodynamically unstable but catalytically promising nitrogen-rich phase of tungsten via a hydrothermal generation of a tungsten oxide intermediate and subsequent annealing in ammonia.The net product consisted of three-dimensional(3D)micron-scale flower-like motifs of W2N3;this architecture not only evinced high structural stability but also incorporated the favorable properties of constituent two-dimensional nanosheets.From a performance perspective,as-prepared 3D W2N3 demonstrated promising hydrogen evolution reaction(HER)activities,especially in an acidic environment with a measured overpotential value of−101 mV at a current density of 10 mA/cm^2.To further enhance the electrocatalytic activity,small amounts of precious metal nanoparticles(such as Pt and Au),consisting of variable sizes,were uniformly deposited onto the underlying 3D W2N3 motifs using a facile direct deposition method;these composites were applied towards the CO2 reduction reaction(CO2RR).A highlight of this series of experiments was that Au/W2N3 composites were found to be a much more active HER(as opposed to either a CO2RR or a methanol oxidation reaction(MOR))catalyst.
基金supported by National Key Research and Development Program of China(Nos.2017YFA0403402,2019YFA0405602)National Natural Science Foundation of China(Nos.21673214,U1732272)+1 种基金Foundation of State Key Laboratory of Coal Conversion(No.J20-21-902)。
文摘With regard to the reaction of higheralcohol synthesis(HAS),the optimizations of activity and selectivity towards C_(2+)alcohol are restricted by the improper equilibrium in two different CO activation pathways and chain growth capacity.Herein,we find that delibrately controlling the compositions of catalysts is an effective strategy to achieve the equilibrium of CO activation pathways and promote the chain growth.As a result,the optimized Cu_(0.25)Co_(0.75) alloy catalyst can achieve a large proportion of higher alcohol in alcohol products(C_(2+)OH/MeOH=4.40),together with high CO conversion of 71.27%and space-time-yield of 147.65 g kg^(-1) h^(-1).The mechanistic studies suggest that the good performance of Cu_(0.25)Co_(0.75) catalyst is attributed to the synergistic effect between alloyed Cu and Co.
基金supported by the National Natural Science Foundation of China(Nos.11471246,11171253)the Natural Science Foundation of the Anhui Higher Education Institutions(No.KJ2014A257)
文摘Cheng-type inequality, Cheeger-type inequality and Faber-Krahn-type inequality are generalized to Finsler manifolds. For a compact Finsler manifold with the weighted Ricci curvature bounded from below by a negative constant, Li-Yau's estimation of the first eigenvalue is also given.
基金supported by National Natural Science Foundation of China(Grant No.11471246)
文摘Studying the geometric flow plays a powerful role in mathematics and physics. In this paper, we introduce the mean curvature flow on Finsler manifolds and give a number of examples of the mean curvature flow. For Minkowski spaces, a special case of Finsler manifolds, we prove the short time existence and uniqueness for solutions of the mean curvature flow and prove that the flow preserves the convexity and mean convexity.We also derive some comparison principles for the mean curvature flow.
基金supported by the National Key Research and Development Program of China (2017YFA0505200 to X.L.)the National Natural Science Foundation of China (21625201, 219611 42010, 91853202 to X.L.+1 种基金32070301, 31872659 to Y.Y.)the Beijing Outstanding Young Scientist Program (BJJWZYJH01201910001001 to X.L.)
文摘Auxin is unique among plant hormones in that its function requires polarized transport across plant cells.A chemiosmotic model was proposed to explain how polar auxin transport is derived by the H^(+)gradient across the plasma membrane(PM)established by PM H^(+)-adenosine triphosphatases(ATPases).However,a classical genetic approach by mutations in PM H^(+)-ATPase members did not result in the ablation of polar auxin distribution,possibly due to functional redundancy in this gene family.To confirm the crucial role of PM H^(+)-ATPases in the polar auxin transport model,we employed a chemical genetic approach.Through a chemical screen,we identified protonstatin-1(PS-1),a selective small-molecule inhibitor of PM H^(+)-ATPase activity that inhibits auxin transport.Assays with transgenic plants and yeast strains showed that the activity of PM H^(+)-ATPases affects auxin uptake as well as acropetal and basipetal polar auxin transport.We propose that PS-1 can be used as a tool to interrogate the function of PM H^(+)-ATPases.Our results support the chemiosmotic model in which PM H^(+)-ATPase itself plays a fundamental role in polar auxin transport.
基金grants from the Beijing Natural Science Foundation (No.7174358)Youth Clinical Research Project of Peking University First Hospital (No.2017CR08) awarded to Gui-Gen Teng.
文摘Background: The effect and mechanism of Saccharomyces boulardii (Sb) in inflammatory bowel disease are unclear. The objective of the study was to evaluate the impact of Sb on intestinal mucosal barrier and intestinal flora in a colitis mouse model. Methods: Forty C57BL/6J male mice were randomly assigned to five groups: normal control group (A), pathologic control group (B), Sb treatment group (C), mesalazine treatment group (D), and Sb combined with mesalazine treatment group (E). Colitis was induced by the addition of 2.5%(wt/vol) dextran sodium sulfate (DSS) in the drinking water ad libitum for 7 days. The general condition, weight change, stool property, and bloody stool level of mice were observed to evaluate the disease activity index. The expression of zona occludens-1 (ZO-1) and occludin in intestinal tissue were measured by immunohistochemistry. The level of tumor necrosis factor-α(TNF-α) and interleukin (IL)-8 in plasma was measured by enzyme linked immunosorbent assay. Inter-cellular tight junctions were observed by transmission electron microscopy. The feces and intestinal contents were collected sterilely, and intestinal flora was analyzed by 16S rRNA sequencing. Results: Compared with group B, Sb reduced the disease activity index and histological score of group C (disease activity index: group B 2.708 ± 0.628, group C 1.542 ± 0.616, PBC = 0.005;histological score: group B 9.875 ± 3.271, group C 4.750 ± 1.832, PBC = 0.005) in DSS-induced colitis in mice. Sb exerted a protect effect on the expression of ZO-1 (group B 2.075 ± 1.176, group C 4.225 ± 1.316, PBC = 0.019) and occludin (group B 2.200 ± 0.968, group C 3.525 ± 1.047, PBC = 0.023). Compared with group B, Sb decreased the level of TNF-α and IL-8 of group C (TNF-α: group B 716.323 ± 44.691 ng/L, group C 521.740 ± 90.121 ng/L, PBC = 0.001;IL-8: group B 128.992 ± 11.475 pg/mL, group C 106.283 ± 15.906 pg/mL, PBC = 0.012). Treatment with Sb preserved the tight junctions and ameliorated microvilli and inter-cellular space. Treatment with Sb also showed its own characteristics: a higher percentage of Bacteroidetes and a lower percentage of Firmicutes, with significant differences or a significant trend. The proportion of the S24-7 family was increased significantly in the Sb treatment group. Conclusions: Sb shows an anti-inflammatory effect and has a protective effect on the intestinal mucosal mechanical barrier. Sb may up-regulate the abundance of family S24-7 specifically, and maybe a mechanism underlying its function.
基金Supported by NNSFC(Grant Nos.11471246 and 11971253)AHNSF(Grant No.1608085MA03)+1 种基金KLAMFJPU(Grant No.SX201805)The authors would like to thank the referees for their time and valuable comments.
文摘In this paper,we give the complete classifications of isoparametric hypersurfaces in Randers space forms.By studying the principal curvatures of anisotropic submanifolds in a Randers space(N,F)with the navigation data(h,W),we find that a Randers space form(N,F,dμBH)and the corresponding Riemannian space(N,h)have the same isoparametric hypersurfaces,but in general,their isoparametric functions are different.We give a necessary and sufficient condition for an isoparametric function of(N,h)to be isoparametric on(N,F,dμBH),from which we get some examples of isoparametric functions.
基金This work is financially supported by the National Basic Research Program of China (No. 2014CB848900), National Natural Science Foundation of China (Nos. U1532112, 11375198, 11574280, and 11605201), CUSF (Nos. WK2310000053, 6030000031), China Scholarship Council and Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Nankai University. L. S. acknowledges the recruitment program of global experts, the CAS Hundred Talent Program. We thank the Shanghai Synchrotron Radiation Facility (14W1, SSRF), the Beijing Synchrotron Radiation Facility (1WIB and soft-X-ray endstation, BSRF), the Hefei Synchrotron Radiation Facility (Photoemission, MCD and Catalysis/Surface Science Endstations, NSRL), and the USTC Center for Micro and Nanoscale Research and Fabrication for help in characterizations. The authors also thank Ms. Ying Luo, Dr. Jun Bao, and Dr. Yu Li for useful discussions.
文摘Rational design and facet-engineering of nanocrystal is an effective strategy to optimize the catalytic performance of abundant and economic semiconductorbased photocatalysts.In this study,we demonstrate a novel ternary Cu2MoS4 nanotube with the {010} facet exposed,synthesized via a hydrothermal method.Compared with two-dimensional Cu2MoS4 nanosheet with the {001} facet exposed,this one-dimensional nanotube exhibits highly enhanced performance of photodegradation and water splitting.Both theoretical calculations and experimental results suggest that the conduction band minimum (CBM) of the {010} facet crystal shows lower potential than that of the {001} facet.In particular,the up-shifted CBM in Cu2MoS4 nanotube is significantly beneficial for the absorption of dye molecules and reduction of H+ to H2.These results may open a new route for realizing high-efficiency photocatalysts based on Cu2MX4 by facet engineering.
基金supported by National Natural Science Foundation of China (Grant Nos. 11971253 and 11471246)AnHui Natural Science Foundation (Grant No. 1608085MA03)。
文摘In this paper, we study isoparametric hypersurfaces in Finsler space forms by investigating focal points, tubes and parallel hypersurfaces of submanifolds. We prove that the focal submanifolds of isoparametric hypersurfaces are anisotropic-minimal and obtain a general Cartan-type formula in a Finsler space form with vanishing reversible torsion, from which we give some classifications on the number of distinct principal curvatures or their multiplicities.
基金This program was financially supported by the National Key R&D Program of China(No.2020YFA0405800)the National Natural Science Foundation of China(NSFC)(Nos.U1932201,and 51902303)+2 种基金CAS International Partnership Program(No.211134KYSB20190063)China Postdoctoral Science Foundation(Nos.BX20200322,and 2020M682009)the Natural Science Foundation of Anhui Province(No.2108085QA31).
文摘To achieve a complete industrial chain of hydrogen energy,the development of efficient electrocatalysts for hydrogen evolution reaction(HER)is of great concerns.Herein,a nickel nitride supported platinum(Pt)catalyst with highly exposed Pt(110)facets(Pt_((110))-Ni_(3)N)is obtained for catalyzing HER.Combined X-ray spectra and density functional theory studies demonstrate that the interfacial electronic interaction between Pt and Ni3N support can promote the hydrogen evolution on Pt(110)facets by weakening hydrogen adsorption.As a result,the Pt_((110))-Ni_(3)N catalyst delivers an obviously higher specific activity than commercial 20 wt.%Pt/C in acidic media.This work suggests that the suitable interface modulation may play a vital role in rationally designing advanced electrocatalysts.