Chemical investigation of the marine-derived fungus Chaetomium globosum HBU-45 led to the discovery of chaeglobol A(1).Its structure was determined by spectroscopic analysis,computational electronic circular dichroism...Chemical investigation of the marine-derived fungus Chaetomium globosum HBU-45 led to the discovery of chaeglobol A(1).Its structure was determined by spectroscopic analysis,computational electronic circular dichroism(ECD)/optical rotatory dispersion(ORD)methods,and X-ray crystallography.Compound 1 represents a new skeleton with an uncommon 6/6/6/5/6/5/6/5 octacyclic system,which is presumably biosynthesized via a[4+2]cycloaddition and an enzymatic cyclization.Chaeglobol A(1)exhibited inhibitory activity against B.dothidea by destroying cell membrane integrity and causing oxidative damage within the cells.展开更多
Due to the atomic-level centrosymmetric spontaneous polarization,antiferroelectric materials exhibit a sensitively nonlinear capacitive response to plural physic fields(mainly electric field and temperature)in a certa...Due to the atomic-level centrosymmetric spontaneous polarization,antiferroelectric materials exhibit a sensitively nonlinear capacitive response to plural physic fields(mainly electric field and temperature)in a certain range,consequently leading to some superb material properties,e.g.,ripple suppression,elec-trocaloric cooling,and dielectric energy storage.However,there are many cognitive blanks about how this exotic multi-field relationε(E_(DC),T)is influenced and manipulated via microscopic structures in the anti-ferroelectrics.In this work,the classic antiferroelectric ceramics PLZT were selected to see this intelligent effect,based on a quad-parameterizedε(E_(DC))relation on the dependence of T.εrelations were studied under different material compositions,temperature,frequency,AC electric field,and DC electric field,re-vealing lattice/domain structure evolution and the underlying mechanism.The inherent phase stability,introduced random field,and hierarchical hysteresis states were found to co-dominate this multi-field nonlinear relation.This work would not only contribute to future progress in the current applications(ripple suppression/electrocaloric cooling/dielectric energy storage)but imply the possibility of co-sensing temperature and electric potential simply and smartly.展开更多
Recently,stimuli-responsive nanocarriers capable of precision drug release have garnered significant attention in the field of drug delivery.Here,an in-situ dynamic covalent self-assembled(DCS)strategy was utilized to...Recently,stimuli-responsive nanocarriers capable of precision drug release have garnered significant attention in the field of drug delivery.Here,an in-situ dynamic covalent self-assembled(DCS)strategy was utilized to develop a co-delivery system.This assembly was based on a thiol-disulfide-exchange reaction,producing disulfide macrocycles in an oxidizing aerial environment.These macrocycles encapsulated the anti-cancer drug(paclitaxel,PTX)on the surface of gold nanoparticles,which served as photothermal therapy agents during the self-assembly.In the DCS process,the kinetic control over the concentration of each building unit within the reaction system led to the formation of a stable co-delivery nanosystem with optimal drug-loading efficiency.Notably,the high glutathione(GSH)concentrations in tumor cells caused the disulfide macrocycles in nanostructures to break,resulting in drug release.The stimuli-responsive performances of the prepared nanosystems were determined by observing the molecular structures and drug release.The results revealed that the self-assembled nanosystem exhibited GSH-triggered drug release and good photothermal conversion capability under near-infrared light.Moreover,the in vitro and in vivo results revealed that conjugating the targeting molecule of cRGD with co-delivery nanosystem enhanced its biocompatibility,chemo-photothermal anti-cancer effect.Overall,our findings indicated that in-situ DCS strategy enhanced the control over drug loading during the construction of the co-delivery system,paving a way for the development of more functional carriers in nanomedicine.展开更多
A dual-scale hybrid HfB_(2)/Cu-Hf composite with HfB_(2) microparticles and Cu_(5) Hf nanoprecipitates was designed and prepared.The contribution of the hybrid effect to the mechanical properties and high-temperature ...A dual-scale hybrid HfB_(2)/Cu-Hf composite with HfB_(2) microparticles and Cu_(5) Hf nanoprecipitates was designed and prepared.The contribution of the hybrid effect to the mechanical properties and high-temperature performances was studied from macro and micro perspectives,respectively.The hybrid of dual-scale particles can make the strain distribution of the composite at the early deformation stage more uniform and delay the strain concentration caused by the HfB_(2) particle.The dislocation pinning of HfB_(2) particles and the coherent strengthening of Cu_(5) Hf nanoprecipitates simultaneously play a strengthening role,but the strength of the hybrid composite is not a simple superposition of two strengthening mod-els.In addition,both Cu_(5) Hf nanoprecipitates and HfB_(2) microparticles contribute to the high-temperature performance of the composite,the growth and phase transition of nanoprecipitates at high temperature will reduce their contribution to strength,while the stable HfB_(2) particles can inhibit the coarsening of matrix grains and maintain the high-density geometrically necessary dislocations(GNDs)in the matrix,which ensures more excellent high-temperature resistance of the hybrid composite.As a result,the hy-brid structure can simultaneously possess the advantages of multiple reinforcements and make up for the shortcomings of each other.Finally,a copper matrix composite with high strength,high conductivity,and excellent high-temperature performance is displayed.展开更多
Ammonia(NH_(3))emission has caused serious environment issues and aroused worldwide concern.The emerging ionic liquid(IL)provides a greener way to efficiently capture NH_(3).This paper provides rigorous process simula...Ammonia(NH_(3))emission has caused serious environment issues and aroused worldwide concern.The emerging ionic liquid(IL)provides a greener way to efficiently capture NH_(3).This paper provides rigorous process simulation,optimization and assessment for a novel NH_(3)deep purification process using IL.The process was designed and investigated by simulation and optimization using ionic liquid[C_(4)im][NTF_(2)]as absorbent.Three objective functions,total purification cost(TPC),total process CO_(2)emission(TPCOE)and thermal efficiency(ηeff)were employed to optimize the absorption process.Process simulation and optimization results indicate that at same purification standard and recovery rate,the novel process can achieve lower cost and CO_(2)emission compared to benchmark process.After process optimization,the optimal functions can achieve 0.02726$/Nm~3(TPC),311.27 kg CO_(2)/hr(TP-COE),and 52.21%(ηeff)for enhanced process.Moreover,compared with conventional process,novel process could decrease over$3 million of purification cost and 10000 tons of CO_(2)emission during the life cycle.The results provide a novel strategy and guidance for deep purification of NH_(3)capture.展开更多
Laser powder bed fusion(LPBF)is a promising method for manufacturing functional and structural integrated Cu-Cr-Zr components.However,the LPBF-processed Cu-Cr-Zr alloys still suffer from the strength-ductility trade-o...Laser powder bed fusion(LPBF)is a promising method for manufacturing functional and structural integrated Cu-Cr-Zr components.However,the LPBF-processed Cu-Cr-Zr alloys still suffer from the strength-ductility trade-offdilemma,while maintaining high conductivity.Here,LPBF-processed Cu-Cr-Zr alloy with a hierarchical structure was obtained by increasing the Cr and Zr content simultaneously.After aging treatment,the hierarchical structure was composed of melt tracks at the macroscale,coarse grains(31.9±0.1μm)and fine grains(5.6±0.2μm)at the microscale,high-density of dislocations and dual precipitates at the nanoscale.The direct aged sample exhibited an excellent combination of strength and ductility(tensile strength was enhanced to 626±1 MPa and uniform elongation of 16.2%±1.1%),which is superior to the traditionally wrought and LPBF-processed Cu-Cr-Zr alloys reported previously.Meantime,a good electrical conductivity of 71.1%±0.3%IACS was also achieved.In addition,the heterogeneous deformation-induced stress caused by the hierarchical structure not only led to a large increase in yield strength but also promoted tensile ductility.展开更多
过渡金属电催化剂因其优良的电催化性能、低廉的成本,以及在电解水、燃料电池、锌空电池等领域展现出极大的应用潜力,逐渐成为人们的研究热点。其中,过渡金属氮化物(Transition Metal Nitrides,TMNs)因氮化过程能使金属的d带收缩变窄,...过渡金属电催化剂因其优良的电催化性能、低廉的成本,以及在电解水、燃料电池、锌空电池等领域展现出极大的应用潜力,逐渐成为人们的研究热点。其中,过渡金属氮化物(Transition Metal Nitrides,TMNs)因氮化过程能使金属的d带收缩变窄,填充态发生改变,从而调节金属-氢的键能,达到提高导电性及催化活性的目的,近来备受学者们的关注。因此,本文综述了TMNs纳米电催化剂的最新研究进展,包括借助d带理论讨论了氮元素对其结构及活性的影响;评述了TMNs的物理、化学等合成方法及掺杂、复合等改性方法;列举了其在析氢反应、析氧反应、氧还原反应等电催化领域中的重要应用;最后,指出了TMNs在现阶段所面临的挑战和问题,并对其今后发展作出展望。展开更多
Conyza sumatrensis （Retz.） E. Walker, a member of Asteraceae, is a highly invasive species. However, its reproduction biology remains poorly known. To understand the role of reproductive traits in successful invasio...Conyza sumatrensis （Retz.） E. Walker, a member of Asteraceae, is a highly invasive species. However, its reproduction biology remains poorly known. To understand the role of reproductive traits in successful invasion of the species, we studied several traits of its reproductive system： the miniature capitulum and gynomonoecious sexual system, the biology and phenology of capitula and florets, pollen/ovule ratio, the mating system （selfcompatibility）, flower visitors, physical traits and dispersal potential of achenes, germination potential of achenes from manually pollinated capitula, and the association of these traits with invasiveness. Our study showed that the reproductive traits of autonomous seed production, versatile mating system of self- and cross-pollination, and generalized pollination system might contribute to the species＇ successful invasive capability. The invasiveness was further enhanced by the high and rapid production of achenes, as well as the high percentage, rapid germination rate and high dispersal capability of achenes. It was concluded that in annual or winter-annual weeds, autonomous seed production contributed significantly to the invasiveness of the species.展开更多
A total of 43 prolonged coma patients with diffuse axonal injury received the somatosensory evoked potential examination one month after injury in the First Affiliated Hospital, School of Medicine, Zhejiang University...A total of 43 prolonged coma patients with diffuse axonal injury received the somatosensory evoked potential examination one month after injury in the First Affiliated Hospital, School of Medicine, Zhejiang University in China. Somatosensory evoked potentials were graded as normal, abnormal or absent （grades I-III） according to N20 amplitude and central conduction time. The outcome in patients with grade III somatosensory evoked potential was in each case unfavorable. The prognostic accuracy of grade III somatosensory evoked potential for unfavorable and non-awakening outcome was 100% and 80%, respectively. The prognostic accuracy of grade I somatosensory evoked potential for favorable and wakening outcome was 86% and 100%, respectively. These results suggest that somatosensory evoked potential grade is closely correlated with coma severity and degree of recovery. Somatosensory evoked potential is a valuable diagnostic tool to assess prognosis in prolonged coma patients with diffuse axonal injury.展开更多
In situ synchrotron X-ray radiography was used to study the effect of direct current（DC） on the grain nucleation and growth of Sn-50 wt.%Pb alloy. The results showed that applying DC adequately during solidification...In situ synchrotron X-ray radiography was used to study the effect of direct current（DC） on the grain nucleation and growth of Sn-50 wt.%Pb alloy. The results showed that applying DC adequately during solidification could effectively enhance the grain nucleation and inhibit its growth. Imaging of comparative experiments with varying DC intensity indicated that the final grain size, determined by the competition between grain nucleation and growth, was sensitively dependent on the DC intensity. It was found that the average grain size was decreased from 1632 to 567 μm with DC density of 1.5 A/mm^2 compared to the case without DC. Beyond this value, raising the current density may cause a significant decrease in the nucleation rate, and thus lead to a coarsening of the grain structure.展开更多
As a novel collector, O-isopropyl-N,N-diethyl thionocarbamate(IPDTC) was designed and synthesized for copper-sulfur flotation separation. Density functional theory calculations were performed to investigate the electr...As a novel collector, O-isopropyl-N,N-diethyl thionocarbamate(IPDTC) was designed and synthesized for copper-sulfur flotation separation. Density functional theory calculations were performed to investigate the electronic structures of IPDTC. The results showed that IPDTC had higher energy of the highest occupied molecular orbital but lower electronegativity than O-isopropyl-N-ethyl thionocarbamate(Z-200). It was predicted that IPDTC had strong collection ability according to the reaction energy criteria. Flotation results demonstrated that the collecting ability of IPDTC to chalcopyrite and pyrite was stronger than that of Z-200. Then, the flotation mechanism was analyzed by measurements of surface tension, adsorption capacity, XPS, FTIR and zeta potential. These results indicated that IPDTC could reduce the solution surface tension. The adsorption capacity of IPDTC on chalcopyrite was higher than that on pyrite, consistent with the results of the flotation tests. FTIR, zeta potential and XPS results also demonstrated that IPDTC was strongly absorbed on the chalcopyrite surface by formation of Cu—S—C bonds, but showed a weak affinity on the pyrite surface.展开更多
Functionalized ionic liquids(FILs)as extractants were employed for the separation of tungsten and molybdenum from a sulfate solution for the first time.The effects of initial pH,extractant concentration,metal concentr...Functionalized ionic liquids(FILs)as extractants were employed for the separation of tungsten and molybdenum from a sulfate solution for the first time.The effects of initial pH,extractant concentration,metal concentrations in the feed were comprehensively investigated.The results showed that tricaprylmethylammonium bis(2,4,4-trimethylpentyl)phosphinate([A336][Cyanex272])could selectively extract W over Mo at an initial pH value of 5.5;the best separation factorβ_(W/Mo) of 25.61 was obtained for a solution with low metal concentrations(WO3:2.49 g/L,Mo:1.04 g/L).The[A336][Cyanex272]system performed effectively for solutions of different W/Mo molar ratios and different metal ion concentrations in the feed.The chemical reaction between[A336][Cyanex272]and W followed the ion association mechanism,which was further proved by the Fourier-transform infrared(FTIR)spectra of loaded[A336][Cyanex272]and the free extractant.The stripping experiments indicated that 95.48%W and 100.00%Mo were stripped using a 0.20 mol/L sodium hydroxide solution.Finally,the selective extractions of W and Mo from two synthetic solutions of different high metal concentrations were obtained;the separation factorβW/Mo reached 23.24 and 17.59 for the first and second solutions,respectively.The results suggest the feasibility of[A336][Cyanex272]as an extractant for the separation of tungsten and molybdenum.展开更多
An optimized silicon carbide(SiC)trench metal-oxide-semiconductor field-effect transistor(MOSFET)structure with side-wall p-type pillar(p-pillar)and wrap n-type pillar(n-pillar)in the n-drain was investigated by utili...An optimized silicon carbide(SiC)trench metal-oxide-semiconductor field-effect transistor(MOSFET)structure with side-wall p-type pillar(p-pillar)and wrap n-type pillar(n-pillar)in the n-drain was investigated by utilizing Silvaco TCAD simulations.The optimized structure mainly includes a p+buried region,a light n-type current spreading layer(CSL),a p-type pillar region,and a wrapping n-type pillar region at the right and bottom of the p-pillar.The improved structure is named as SNPPT-MOS.The side-wall p-pillar region could better relieve the high electric field around the p+shielding region and the gate oxide in the off-state mode.The wrapping n-pillar region and CSL can also effectively reduce the specific on-resistance(Ron,sp).As a result,the SNPPT-MOS structure exhibits that the figure of merit(Fo M)related to the breakdown voltage(V_(BR))and Ron,sp(V_(BR)^2R_(on,sp))of the SNPPT-MOS is improved by 44.5%,in comparison to that of the conventional trench gate SJ MOSFET(full-SJ-MOS).In addition,the SNPPT-MOS structure achieves a much fasterwitching speed than the full-SJ-MOS,and the result indicates an appreciable reduction in the switching energy loss.展开更多
In situ TiB2/Cu composites were fabricated by both solid-liquid(S-L)and liquid-liquid(L-L)reactive spray deposition in combination with cold rolling and annealing.The microstructure and properties of the fabricated Ti...In situ TiB2/Cu composites were fabricated by both solid-liquid(S-L)and liquid-liquid(L-L)reactive spray deposition in combination with cold rolling and annealing.The microstructure and properties of the fabricated TiB2/Cu composites were investigated.The results show that the reactive mode and rolling treatment are the main factors affecting the microstructure and properties of the TiB2/Cu composite.The in situ reaction in the L-L reaction can be carried out more completely.By controlling the rolling and annealing process,the relative density and the properties of the as-deposited composites are optimized.The comprehensive performance of the deformed TiB2/Cu composite prepared by L-L reactive spray deposition(401 MPa and 83.5%IACS)is better than that by S-L reactive spray deposition(520 MPa and 20.2%IACS).展开更多
This article investigates an improved 4H-SiC trench gate metal–oxide–semiconductor field-effect transistor(MOSFET)(UMOSFET)fitted with a super-junction(SJ)shielded region.The modified structure is composed of two n-...This article investigates an improved 4H-SiC trench gate metal–oxide–semiconductor field-effect transistor(MOSFET)(UMOSFET)fitted with a super-junction(SJ)shielded region.The modified structure is composed of two n-type conductive pillars,three p-type conductive pillars,an oxide trench under the gate,and a light n-type current spreading layer(NCSL)under the p-body.The n-type conductive pillars and the light n-type current spreading layer provide two paths to and promote the diffusion of a transverse current in the epitaxial layer,thus improving the specific on-resistance(R_(on,sp)).There are three p-type pillars in the modified structure,with the p-type pillars on both sides playing the same role.The p-type conductive pillars relieve the electric field(E-field)in the corner of the trench bottom.Two-dimensional simulation(silvaco TCAD)indicates that Ron,sp of the modified structure,and breakdown voltage(V_(BR))are improved by 22.2%and 21.1%respectively,while the maximum figure of merit(FOM=V_(BR)^(2)/R_(on,sp)) is improved by 79.0%.Furthermore,the improved structure achieves a light smaller low gate-to-drain charge(Q_(gd))and when compared with the conventional UMOSFET(conventional-UMOS),it displays great advantages for reducing the switching energy loss.These advantages are due to the fact that the p-type conductive pillars and n-type conductive pillars configured under the gate provide a substantial charge balance,which also enables the charge carriers to be extracted quickly.In the end,under the condition of the same total charge quantity,the simulation comparison of gate charge and OFF-state characteristics between Gaussdoped structure and uniform-doped structure shows that Gauss-doped structure increases the V_(BR)of the device without degradation of dynamic performance.展开更多
Copper matrix composites reinforced by in situ-formed hybrid titanium boride whiskers(TiB_(w))and titanium diboride particles(TiB_(2p))were fabricated by powder metallurgy.Microstructural observations showed competiti...Copper matrix composites reinforced by in situ-formed hybrid titanium boride whiskers(TiB_(w))and titanium diboride particles(TiB_(2p))were fabricated by powder metallurgy.Microstructural observations showed competitive precipitation behavior between TiB_(w) and TiB_(2p),where the relative contents of the two reinforcements varied with sintering temperature.Based on thermodynamic and kinetic assessments,the precipitation mechanisms of the hybrid reinforcements were discussed,and the formation of both TiB_(w) and TiB_(2p) from the local melting zone was thermodynamically favored.The precipitation kinetics were mainly controlled by a solid-state diffusion of B atoms.By forming a compact compound layer,in situ reactions were divided into two stages,where Zener growth and Dybkov growth prevailed,respectively.Accordingly,the competitive precipitation behavior was attributed to the transition of the growth model during the reaction process.展开更多
基金funded by the S&T Program of Hebei(No.21323202D)the Natural Science Interdisciplinary Research Program of Hebei University(No.DXK201913)+4 种基金the Natural Sci-ence Foundation of Hebei Province of China(Nos.H2024201028,H2020201029)the Excellent Youth Research Innovation Team of Hebei University(No.QNTD202406)the Hebei University Research and Innovation Team(No.IT2023C1)the Innovation Capacity Improvement Plan of Hebei Province(No.20567605H)the National Training Program of Innovation and Entrepreneurship for Undergraduates(No.DC2024177)。
文摘Chemical investigation of the marine-derived fungus Chaetomium globosum HBU-45 led to the discovery of chaeglobol A(1).Its structure was determined by spectroscopic analysis,computational electronic circular dichroism(ECD)/optical rotatory dispersion(ORD)methods,and X-ray crystallography.Compound 1 represents a new skeleton with an uncommon 6/6/6/5/6/5/6/5 octacyclic system,which is presumably biosynthesized via a[4+2]cycloaddition and an enzymatic cyclization.Chaeglobol A(1)exhibited inhibitory activity against B.dothidea by destroying cell membrane integrity and causing oxidative damage within the cells.
基金supported by the National Natural Science Foun-dation of China(Grant Nos.U2002217,11774366 and 52102342).
文摘Due to the atomic-level centrosymmetric spontaneous polarization,antiferroelectric materials exhibit a sensitively nonlinear capacitive response to plural physic fields(mainly electric field and temperature)in a certain range,consequently leading to some superb material properties,e.g.,ripple suppression,elec-trocaloric cooling,and dielectric energy storage.However,there are many cognitive blanks about how this exotic multi-field relationε(E_(DC),T)is influenced and manipulated via microscopic structures in the anti-ferroelectrics.In this work,the classic antiferroelectric ceramics PLZT were selected to see this intelligent effect,based on a quad-parameterizedε(E_(DC))relation on the dependence of T.εrelations were studied under different material compositions,temperature,frequency,AC electric field,and DC electric field,re-vealing lattice/domain structure evolution and the underlying mechanism.The inherent phase stability,introduced random field,and hierarchical hysteresis states were found to co-dominate this multi-field nonlinear relation.This work would not only contribute to future progress in the current applications(ripple suppression/electrocaloric cooling/dielectric energy storage)but imply the possibility of co-sensing temperature and electric potential simply and smartly.
基金supported by the National Natural Science Foundation of China(Nos.82202274,82072032,22161016,32025021,12374390,52002380 and 31971292),the National Science and Technology Major Project(No.2023ZD0500902)the Fellowship of China Postdoctoral Science Foundation(No.2023M743559)+2 种基金the Member of Youth Innovation Promotion Association Foundation of CAS,China(No.2023310)the Key Scientific and Technological Special Project of Ningbo City(No.2023Z209)the Natural Science Foundation of Zhejiang Province(No.LQ23H180003)。
文摘Recently,stimuli-responsive nanocarriers capable of precision drug release have garnered significant attention in the field of drug delivery.Here,an in-situ dynamic covalent self-assembled(DCS)strategy was utilized to develop a co-delivery system.This assembly was based on a thiol-disulfide-exchange reaction,producing disulfide macrocycles in an oxidizing aerial environment.These macrocycles encapsulated the anti-cancer drug(paclitaxel,PTX)on the surface of gold nanoparticles,which served as photothermal therapy agents during the self-assembly.In the DCS process,the kinetic control over the concentration of each building unit within the reaction system led to the formation of a stable co-delivery nanosystem with optimal drug-loading efficiency.Notably,the high glutathione(GSH)concentrations in tumor cells caused the disulfide macrocycles in nanostructures to break,resulting in drug release.The stimuli-responsive performances of the prepared nanosystems were determined by observing the molecular structures and drug release.The results revealed that the self-assembled nanosystem exhibited GSH-triggered drug release and good photothermal conversion capability under near-infrared light.Moreover,the in vitro and in vivo results revealed that conjugating the targeting molecule of cRGD with co-delivery nanosystem enhanced its biocompatibility,chemo-photothermal anti-cancer effect.Overall,our findings indicated that in-situ DCS strategy enhanced the control over drug loading during the construction of the co-delivery system,paving a way for the development of more functional carriers in nanomedicine.
基金supported by the National Natural Science Foundation of China(Nos.52127802,52271137,and 51834009).
文摘A dual-scale hybrid HfB_(2)/Cu-Hf composite with HfB_(2) microparticles and Cu_(5) Hf nanoprecipitates was designed and prepared.The contribution of the hybrid effect to the mechanical properties and high-temperature performances was studied from macro and micro perspectives,respectively.The hybrid of dual-scale particles can make the strain distribution of the composite at the early deformation stage more uniform and delay the strain concentration caused by the HfB_(2) particle.The dislocation pinning of HfB_(2) particles and the coherent strengthening of Cu_(5) Hf nanoprecipitates simultaneously play a strengthening role,but the strength of the hybrid composite is not a simple superposition of two strengthening mod-els.In addition,both Cu_(5) Hf nanoprecipitates and HfB_(2) microparticles contribute to the high-temperature performance of the composite,the growth and phase transition of nanoprecipitates at high temperature will reduce their contribution to strength,while the stable HfB_(2) particles can inhibit the coarsening of matrix grains and maintain the high-density geometrically necessary dislocations(GNDs)in the matrix,which ensures more excellent high-temperature resistance of the hybrid composite.As a result,the hy-brid structure can simultaneously possess the advantages of multiple reinforcements and make up for the shortcomings of each other.Finally,a copper matrix composite with high strength,high conductivity,and excellent high-temperature performance is displayed.
基金supported by the National Natural Science Foundation of China (Nos.21890760 and 21838010)the Science Fund for Creative Research Groups of the National Natural Science Foundation of China (No.21921005)the International (Regional)Cooperation and Exchange of the National Natural Science Foundation of China (No.21961160744)。
文摘Ammonia(NH_(3))emission has caused serious environment issues and aroused worldwide concern.The emerging ionic liquid(IL)provides a greener way to efficiently capture NH_(3).This paper provides rigorous process simulation,optimization and assessment for a novel NH_(3)deep purification process using IL.The process was designed and investigated by simulation and optimization using ionic liquid[C_(4)im][NTF_(2)]as absorbent.Three objective functions,total purification cost(TPC),total process CO_(2)emission(TPCOE)and thermal efficiency(ηeff)were employed to optimize the absorption process.Process simulation and optimization results indicate that at same purification standard and recovery rate,the novel process can achieve lower cost and CO_(2)emission compared to benchmark process.After process optimization,the optimal functions can achieve 0.02726$/Nm~3(TPC),311.27 kg CO_(2)/hr(TP-COE),and 52.21%(ηeff)for enhanced process.Moreover,compared with conventional process,novel process could decrease over$3 million of purification cost and 10000 tons of CO_(2)emission during the life cycle.The results provide a novel strategy and guidance for deep purification of NH_(3)capture.
基金supported by the National Natural Science Foundation of China(Nos.52127802 and 51834009)the Science and Technology Project of Xi’an(No.2021SFGX0004).
文摘Laser powder bed fusion(LPBF)is a promising method for manufacturing functional and structural integrated Cu-Cr-Zr components.However,the LPBF-processed Cu-Cr-Zr alloys still suffer from the strength-ductility trade-offdilemma,while maintaining high conductivity.Here,LPBF-processed Cu-Cr-Zr alloy with a hierarchical structure was obtained by increasing the Cr and Zr content simultaneously.After aging treatment,the hierarchical structure was composed of melt tracks at the macroscale,coarse grains(31.9±0.1μm)and fine grains(5.6±0.2μm)at the microscale,high-density of dislocations and dual precipitates at the nanoscale.The direct aged sample exhibited an excellent combination of strength and ductility(tensile strength was enhanced to 626±1 MPa and uniform elongation of 16.2%±1.1%),which is superior to the traditionally wrought and LPBF-processed Cu-Cr-Zr alloys reported previously.Meantime,a good electrical conductivity of 71.1%±0.3%IACS was also achieved.In addition,the heterogeneous deformation-induced stress caused by the hierarchical structure not only led to a large increase in yield strength but also promoted tensile ductility.
文摘过渡金属电催化剂因其优良的电催化性能、低廉的成本,以及在电解水、燃料电池、锌空电池等领域展现出极大的应用潜力,逐渐成为人们的研究热点。其中,过渡金属氮化物(Transition Metal Nitrides,TMNs)因氮化过程能使金属的d带收缩变窄,填充态发生改变,从而调节金属-氢的键能,达到提高导电性及催化活性的目的,近来备受学者们的关注。因此,本文综述了TMNs纳米电催化剂的最新研究进展,包括借助d带理论讨论了氮元素对其结构及活性的影响;评述了TMNs的物理、化学等合成方法及掺杂、复合等改性方法;列举了其在析氢反应、析氧反应、氧还原反应等电催化领域中的重要应用;最后,指出了TMNs在现阶段所面临的挑战和问题,并对其今后发展作出展望。
基金supported by the Special Scientific Research Program for Non-profit Professions (200709017)
文摘Conyza sumatrensis （Retz.） E. Walker, a member of Asteraceae, is a highly invasive species. However, its reproduction biology remains poorly known. To understand the role of reproductive traits in successful invasion of the species, we studied several traits of its reproductive system： the miniature capitulum and gynomonoecious sexual system, the biology and phenology of capitula and florets, pollen/ovule ratio, the mating system （selfcompatibility）, flower visitors, physical traits and dispersal potential of achenes, germination potential of achenes from manually pollinated capitula, and the association of these traits with invasiveness. Our study showed that the reproductive traits of autonomous seed production, versatile mating system of self- and cross-pollination, and generalized pollination system might contribute to the species＇ successful invasive capability. The invasiveness was further enhanced by the high and rapid production of achenes, as well as the high percentage, rapid germination rate and high dispersal capability of achenes. It was concluded that in annual or winter-annual weeds, autonomous seed production contributed significantly to the invasiveness of the species.
基金funded by Zhejiang Medicines &Health Sciences Research Fund (Class A) in 2009, No.2009A086
文摘A total of 43 prolonged coma patients with diffuse axonal injury received the somatosensory evoked potential examination one month after injury in the First Affiliated Hospital, School of Medicine, Zhejiang University in China. Somatosensory evoked potentials were graded as normal, abnormal or absent （grades I-III） according to N20 amplitude and central conduction time. The outcome in patients with grade III somatosensory evoked potential was in each case unfavorable. The prognostic accuracy of grade III somatosensory evoked potential for unfavorable and non-awakening outcome was 100% and 80%, respectively. The prognostic accuracy of grade I somatosensory evoked potential for favorable and wakening outcome was 86% and 100%, respectively. These results suggest that somatosensory evoked potential grade is closely correlated with coma severity and degree of recovery. Somatosensory evoked potential is a valuable diagnostic tool to assess prognosis in prolonged coma patients with diffuse axonal injury.
基金supported by the National Key Research and Development Program of China (No. 2016YFB0701203)the National Natural Science Foundation of China (Nos. 51525401, 51690163, 51601028, 51401044)Dalian Support Plan for Innovation of High-level Talents (Top and Leading Talents, 2015R013)
文摘In situ synchrotron X-ray radiography was used to study the effect of direct current（DC） on the grain nucleation and growth of Sn-50 wt.%Pb alloy. The results showed that applying DC adequately during solidification could effectively enhance the grain nucleation and inhibit its growth. Imaging of comparative experiments with varying DC intensity indicated that the final grain size, determined by the competition between grain nucleation and growth, was sensitively dependent on the DC intensity. It was found that the average grain size was decreased from 1632 to 567 μm with DC density of 1.5 A/mm^2 compared to the case without DC. Beyond this value, raising the current density may cause a significant decrease in the nucleation rate, and thus lead to a coarsening of the grain structure.
基金financial supports from the Open Foundation of State Key Laboratory of Mineral Processing,China (Nos.BGRIMM-KJSKL-2019-06,BGRIMMKJSKL-2022-13)the Open Fund of State Key Laboratory of Comprehensive Utilization of Low-Grade,China (No.ZJKY2017(B)KFJJ003)。
文摘As a novel collector, O-isopropyl-N,N-diethyl thionocarbamate(IPDTC) was designed and synthesized for copper-sulfur flotation separation. Density functional theory calculations were performed to investigate the electronic structures of IPDTC. The results showed that IPDTC had higher energy of the highest occupied molecular orbital but lower electronegativity than O-isopropyl-N-ethyl thionocarbamate(Z-200). It was predicted that IPDTC had strong collection ability according to the reaction energy criteria. Flotation results demonstrated that the collecting ability of IPDTC to chalcopyrite and pyrite was stronger than that of Z-200. Then, the flotation mechanism was analyzed by measurements of surface tension, adsorption capacity, XPS, FTIR and zeta potential. These results indicated that IPDTC could reduce the solution surface tension. The adsorption capacity of IPDTC on chalcopyrite was higher than that on pyrite, consistent with the results of the flotation tests. FTIR, zeta potential and XPS results also demonstrated that IPDTC was strongly absorbed on the chalcopyrite surface by formation of Cu—S—C bonds, but showed a weak affinity on the pyrite surface.
基金financially supported by the National Natural Science Foundation of China(No.51504225).
文摘Functionalized ionic liquids(FILs)as extractants were employed for the separation of tungsten and molybdenum from a sulfate solution for the first time.The effects of initial pH,extractant concentration,metal concentrations in the feed were comprehensively investigated.The results showed that tricaprylmethylammonium bis(2,4,4-trimethylpentyl)phosphinate([A336][Cyanex272])could selectively extract W over Mo at an initial pH value of 5.5;the best separation factorβ_(W/Mo) of 25.61 was obtained for a solution with low metal concentrations(WO3:2.49 g/L,Mo:1.04 g/L).The[A336][Cyanex272]system performed effectively for solutions of different W/Mo molar ratios and different metal ion concentrations in the feed.The chemical reaction between[A336][Cyanex272]and W followed the ion association mechanism,which was further proved by the Fourier-transform infrared(FTIR)spectra of loaded[A336][Cyanex272]and the free extractant.The stripping experiments indicated that 95.48%W and 100.00%Mo were stripped using a 0.20 mol/L sodium hydroxide solution.Finally,the selective extractions of W and Mo from two synthetic solutions of different high metal concentrations were obtained;the separation factorβW/Mo reached 23.24 and 17.59 for the first and second solutions,respectively.The results suggest the feasibility of[A336][Cyanex272]as an extractant for the separation of tungsten and molybdenum.
基金the National Natural Science Foundation of China(Grant Nos.61774052 and 61904045)the National Natural Science Foundation of Jiangxi Province of China(Grant No.20202BABL201021)the Education Department of Jiangxi Province of China for Youth Foundation(Grant No.GJJ191154)。
文摘An optimized silicon carbide(SiC)trench metal-oxide-semiconductor field-effect transistor(MOSFET)structure with side-wall p-type pillar(p-pillar)and wrap n-type pillar(n-pillar)in the n-drain was investigated by utilizing Silvaco TCAD simulations.The optimized structure mainly includes a p+buried region,a light n-type current spreading layer(CSL),a p-type pillar region,and a wrapping n-type pillar region at the right and bottom of the p-pillar.The improved structure is named as SNPPT-MOS.The side-wall p-pillar region could better relieve the high electric field around the p+shielding region and the gate oxide in the off-state mode.The wrapping n-pillar region and CSL can also effectively reduce the specific on-resistance(Ron,sp).As a result,the SNPPT-MOS structure exhibits that the figure of merit(Fo M)related to the breakdown voltage(V_(BR))and Ron,sp(V_(BR)^2R_(on,sp))of the SNPPT-MOS is improved by 44.5%,in comparison to that of the conventional trench gate SJ MOSFET(full-SJ-MOS).In addition,the SNPPT-MOS structure achieves a much fasterwitching speed than the full-SJ-MOS,and the result indicates an appreciable reduction in the switching energy loss.
基金Projects(U1502274,51834009)supported by the National Natural Science Foundation of ChinaProject(2017ZDXM-GY-028)supported by the Key Research and Development Program of Shaanxi,China。
文摘In situ TiB2/Cu composites were fabricated by both solid-liquid(S-L)and liquid-liquid(L-L)reactive spray deposition in combination with cold rolling and annealing.The microstructure and properties of the fabricated TiB2/Cu composites were investigated.The results show that the reactive mode and rolling treatment are the main factors affecting the microstructure and properties of the TiB2/Cu composite.The in situ reaction in the L-L reaction can be carried out more completely.By controlling the rolling and annealing process,the relative density and the properties of the as-deposited composites are optimized.The comprehensive performance of the deformed TiB2/Cu composite prepared by L-L reactive spray deposition(401 MPa and 83.5%IACS)is better than that by S-L reactive spray deposition(520 MPa and 20.2%IACS).
基金the National Natural Science Foundation of China(Grant Nos.61774052 and 61904045)the Youth Foundation of the Education Department of Jiangxi Province,China(Grant No.GJJ191154)the Youth Foundation of Ping Xiang University,China(Grant No.2018D0230).
文摘This article investigates an improved 4H-SiC trench gate metal–oxide–semiconductor field-effect transistor(MOSFET)(UMOSFET)fitted with a super-junction(SJ)shielded region.The modified structure is composed of two n-type conductive pillars,three p-type conductive pillars,an oxide trench under the gate,and a light n-type current spreading layer(NCSL)under the p-body.The n-type conductive pillars and the light n-type current spreading layer provide two paths to and promote the diffusion of a transverse current in the epitaxial layer,thus improving the specific on-resistance(R_(on,sp)).There are three p-type pillars in the modified structure,with the p-type pillars on both sides playing the same role.The p-type conductive pillars relieve the electric field(E-field)in the corner of the trench bottom.Two-dimensional simulation(silvaco TCAD)indicates that Ron,sp of the modified structure,and breakdown voltage(V_(BR))are improved by 22.2%and 21.1%respectively,while the maximum figure of merit(FOM=V_(BR)^(2)/R_(on,sp)) is improved by 79.0%.Furthermore,the improved structure achieves a light smaller low gate-to-drain charge(Q_(gd))and when compared with the conventional UMOSFET(conventional-UMOS),it displays great advantages for reducing the switching energy loss.These advantages are due to the fact that the p-type conductive pillars and n-type conductive pillars configured under the gate provide a substantial charge balance,which also enables the charge carriers to be extracted quickly.In the end,under the condition of the same total charge quantity,the simulation comparison of gate charge and OFF-state characteristics between Gaussdoped structure and uniform-doped structure shows that Gauss-doped structure increases the V_(BR)of the device without degradation of dynamic performance.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.U1502274,51834009,and 51974244).
文摘Copper matrix composites reinforced by in situ-formed hybrid titanium boride whiskers(TiB_(w))and titanium diboride particles(TiB_(2p))were fabricated by powder metallurgy.Microstructural observations showed competitive precipitation behavior between TiB_(w) and TiB_(2p),where the relative contents of the two reinforcements varied with sintering temperature.Based on thermodynamic and kinetic assessments,the precipitation mechanisms of the hybrid reinforcements were discussed,and the formation of both TiB_(w) and TiB_(2p) from the local melting zone was thermodynamically favored.The precipitation kinetics were mainly controlled by a solid-state diffusion of B atoms.By forming a compact compound layer,in situ reactions were divided into two stages,where Zener growth and Dybkov growth prevailed,respectively.Accordingly,the competitive precipitation behavior was attributed to the transition of the growth model during the reaction process.
