Despite the industrial significance of grain size for enhancing mechanical properties and formability,the in-depth deformation mechanisms at elevated temperature are still unclear.To investigate the functions of grain...Despite the industrial significance of grain size for enhancing mechanical properties and formability,the in-depth deformation mechanisms at elevated temperature are still unclear.To investigate the functions of grain size on hot workability and deformation mechanisms,three groups of Mg-1.2Zn-0.2Y alloy specimens with different grain sizes were hot compressed and then studied by combining constitutive model,processing map and microstructural observations.The results showed that the enhanced hot workability accompanying low deformation activation energy and small instability regime was obtained with refined grain size.During hot deformation,the decreased grain size in Mg1.2Zn-0.2Y alloy mainly improved the plastic deformation homogeneity,especially for the weakened local straining around grain boundaries.As a result,the dynamic recrystallization nucleation and texture development at lower strain level were influenced by the initial grain size.At higher strain magnitude,the growth and coarsening of dynamic recrystallized grains would further release strain localization and improve hot workability,while the texture was less impacted.Further,unlike the primary basal slip and deformation twinning in the specimen with coarse grain at low temperature,non-basal slips of dislocations were initiated with less deformation twins in the specimens with refined grain size.展开更多
Two-dimensional(2D)oxides have been the focus of substantial research interest recently,owing to their fascinating physico-chemical properties.However,fabrication of large-area 2D oxide materials in a controlled manne...Two-dimensional(2D)oxides have been the focus of substantial research interest recently,owing to their fascinating physico-chemical properties.However,fabrication of large-area 2D oxide materials in a controlled manner under mild conditions still remains a formidable challenge.Herein,we develop a facile and universal strategy based on the sonochemistry approach for controllable and large-area growth of quasi-aligned single-crystalline ZnO nanosheets on a Zn substrate(Zn@SC-ZnO)under ambient conditions.The obtained ZnO nanosheets possess the desired exclusively exposed(001)facets,which have been confirmed to play a critical role in significantly reducing the activation energy and facilitating the stripping/plating processes of Zn.Accordingly,the constructed Zn@SC-ZnO||Zn@SC-ZnO symmetric cell has very low polarization overpotential down to~20 mV,with limited dendrite growth and side reactions for Zn anodes.The developed Zn@SC-ZnO//MnO_(2)aqueous Zn-ion batteries(ZIBs)show a voltage efficiency of 88.2%under 500 mA g^(-1)at the stage of 50%depth of discharge,which is state of the art for ZIBs reported to date.Furthermore,the as-assembled large-size cell(5 cm×5 cm)delivers an open circuit potential of 1.648 V,and can be robustly operated under a high current of 20 mA,showing excellent potential for future scalable applications.展开更多
We report the scalable fabrication of CdS/ZnS 1D/2D heterojunctions under ambient air conditions(i.e.,room temperature and atmospheric pressure)in which ZnS nanoparticles are anchored on the surface of CdS nanosheets....We report the scalable fabrication of CdS/ZnS 1D/2D heterojunctions under ambient air conditions(i.e.,room temperature and atmospheric pressure)in which ZnS nanoparticles are anchored on the surface of CdS nanosheets.The as-formed heterojunctions exhibit a significantly enhanced photocatalytic H_(2) evolution rate of 14.02 mmol h^(-1) g^(-1) when irradiated with visible light,which is~10 and 85 times higher than those of pristine CdS nanosheets and CdS nanoparticles,respectively,and superior to most of the CdS-based photocatalysts reported to date.Furthermore,they provide robust photocatalytic performance with demonstratable stability over 58 h,indicating their potential for practical applications.The formation of 1D/2D heterojunctions not only provides improved exposed active sites that respond to illumination but also provides a rapid pathway to generate photogenerated carriers for efficient separation and transfer through the matrix of single-crystalline CdS nanosheets.In addition,first-principles simulations demonstrate that the existence of rich Zn vacancies increases the energy level of the ZnS valence band maximum to construct type-II and Z-scheme mixed heterojunctions,which plays a critical role in suppressing the recombination of carriers with limited photocorrosion of CdS to enhance photocatalytic behavior.展开更多
The linkage between Qi and mitochondria was investigated by exploring the effect of Traditional Chinese Medicine (TCM) Qi-invigorating herbs on mitochondrial function at the biochemical and molecular levels. Three Chi...The linkage between Qi and mitochondria was investigated by exploring the effect of Traditional Chinese Medicine (TCM) Qi-invigorating herbs on mitochondrial function at the biochemical and molecular levels. Three Chinese herbs (<i></span><i><span style="font-family:Verdana;">Astragali radix</span></i><span style="font-family:Verdana;">,</span><i><span style="font-family:Verdana;"> Herba cistanche</span></i><span style="font-family:Verdana;">, </span><i><span style="font-family:Verdana;">Panax ginseng</span></i><span style="font-family:Verdana;"></i>) were used to treat cultured mouse kidney cells and the generation of adenosine triphosphate (ATP) was measured. The Qi-invigorating herb, <i></span><i><span style="font-family:Verdana;">Astragali radix</span></i><span style="font-family:Verdana;"></i>, was selected for further </span></span><span style="font-family:""><span style="font-family:Verdana;">study using additional biological and molecular parameters, including ATP, reactive oxygen species (ROS), mitochondrial membrane potential (MMP),</span><span><span style="font-family:Verdana;"> mtDNA copies, superoxide dismutase (SOD), glutathione (GSH), cell growth, cell viability and transcriptomes. We also chose two concentrations of <i></span><i><span style="font-family:Verdana;">Astragali radix</span></i><span style="font-family:Verdana;"></i> to study the hormetic effect. The results indicated that: 1) Qi-invigorating herbs have significant effects on the function of mitochondria, with ATP production and the antioxidant capacity being significantly enhanced, and ROS le</span></span><span style="font-family:Verdana;">vels being reduced, allowing for a more optimal oxidation environment. The effect of the herbs followed a hormetic curve with a stimulating effect at lower</span><span> </span><span style="font-family:Verdana;">doses but an inhibiting effect at high doses;2) The growth of the cells was not</span><span> </span><span style="font-family:Verdana;">affected despite numerous biochemical changes associated with mitochondrial</span><span> </span><span style="font-family:Verdana;">function, indicating the powerful ability of mitochondria to maintain cellular homeostasis;3) The up-regulation of NOCT gene, related to nicotinamide adenine dinucleotide (NADH) synthesis, offers a molecular basis for the ATP-promoting effect of the Qi-invigorating herbs. This work provides additional insight into the efficacy of TCM herbs from a western perspective.展开更多
<i><span style="font-family:Verdana;">Objectives</span></i><span style="font-family:Verdana;"></i>: To explore the effects of Qi-invigorating herbs on mitochondr...<i><span style="font-family:Verdana;">Objectives</span></i><span style="font-family:Verdana;"></i>: To explore the effects of Qi-invigorating herbs on mitochondrial function using cultured cells and animal organs. <i></span><i><span style="font-family:Verdana;">Methods</span></i><span style="font-family:Verdana;"></i>: Using water extracts of <i></span><i><span style="font-family:Verdana;">Astragali radix</span></i><span style="font-family:Verdana;"></i>, we investigated the effect of “Qi-invigoration” on M-1 renal cells and mouse organs <i></span><i><span style="font-family:Verdana;">in-vitro</span></i><span style="font-family:Verdana;"></i> including total adenylate production (TAP), reactive oxygen species (ROS) levels, and mitochondrial membrane potential (MMP). We also examined the effect on antioxidant capacity by conducting an analysis of superoxide dismutase (SOD) and glutathione (GSH). <i></span><i><span style="font-family:Verdana;">Results</span></i><span style="font-family:Verdana;"></i>: 1) <i></span><i><span style="font-family:Verdana;">Astragali radix</span></i><span style="font-family:Verdana;"></i> increased mitochondrial TAP generation and decreased ROS levels in both mouse kidney tissues and M-1 renal cells. 2) <i></span><i><span style="font-family:Verdana;">Astragali radix</span></i><span style="font-family:Verdana;"></i> also significantly increased MMP and GSH levels in M-1 cells, but in the kidney tissue</span><span style="font-family:Verdana;">,</span><span style="font-family:""><span style="font-family:Verdana;"> there was no significant change in MMP levels and a decrease in GSH levels. 3) <i></span><i><span style="font-family:Verdana;">Astragali radix</span></i><span style="font-family:Verdana;"></i> stimulated TAP levels in the heart, spleen, lung, kidney and skeletal muscle tissue, which was accompanied by the reduction of ROS. 4) For the meridian organs that <i></span><i><span style="font-family:Verdana;">Astragali radix</span></i><span style="font-family:Verdana;"></i> belongs to, the energy production and antioxidant capacity were boosted simultaneously. <i></span><i><span style="font-family:Verdana;">Conclusions</span></i><span style="font-family:Verdana;"></i>: These results provide new insights for the biochemical </span><span style="font-family:Verdana;">b</span><span style="font-family:Verdana;">asis of Qi-invigoration and the meridian tropism theory for this Qi-invigora</span><span style="font-family:Verdana;">ting herb.</span></span>展开更多
<i><span style="font-family:Verdana;">Astragali Radix </span></i><span style="font-family:Verdana;">(AR), the dried root of legumes, belongs to the Qi-invigorating<...<i><span style="font-family:Verdana;">Astragali Radix </span></i><span style="font-family:Verdana;">(AR), the dried root of legumes, belongs to the Qi-invigorating</span><span style="font-family:""> <span style="font-family:Verdana;">herbs in traditional Chinese medicine and plays an important role in the</span><span style="font-family:Verdana;"> treatment of many diseases. In order to understand the mechanism of action of AR extract. We used AR extract to treat M-1, mouse kidney cells, and used transcriptome sequencing technology to detect the genomic transcription level of the cells under the action of AR at different concentrations and times. The results showed that after a low concentration of AR treatments on the cells, the expression of genes related to cell growth and cellular immune response changed significantly, among which multiple genes are related to mitochondrial function, while high concentrations of AR affected the expression of histones and disease-related genes. It showed that the low concentration of AR extract can achieve the effect of invigorating Qi by regulating the function of mitochondria. In addition, several important genes and pathways were identified as potential targets of AR activation. The research not only clarified the main molecular biological mechanism of AR invigorating Qi, but also provided experimental basis and cellular physiology reference for the further clinical application of AR.展开更多
Graphene-reinforced aluminum(Al) matrix composites were successfully prepared via solution mixing and powder metallurgy in this study. The mechanical properties of the composites were studied using microhardness and t...Graphene-reinforced aluminum(Al) matrix composites were successfully prepared via solution mixing and powder metallurgy in this study. The mechanical properties of the composites were studied using microhardness and tensile tests. Compared to the pure Al alloy, the graphene/Al composites showed increased strength and hardness. A tensile strength of 255 MPa was achieved for the graphene/Al composite with only 0.3 wt% graphene, which has a 25% increase over the tensile strength of the pure Al matrix. Raman spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy were used to investigate the morphologies, chemical compositions, and microstructures of the graphene and the graphene/Al composites. On the basis of fractographic evidence, a relevant fracture mechanism is proposed.展开更多
Biodegradable magnesium alloys as new biomedical implant materials have been extensively studied because of their notable biodegradability over traditional bio-inert metals.However,the extreme degradation rate of pure...Biodegradable magnesium alloys as new biomedical implant materials have been extensively studied because of their notable biodegradability over traditional bio-inert metals.However,the extreme degradation rate of pure magnesium leads to the loss of its mechanical integrity before the tissue recovers completely.The solutions to this challenge are as follows:(1)purification,(2)alloying,(3)surface modification,and(4)biodegradable magnesium-matrix composites(BMMCs)synthesis.Owing to the tunability of mechanical properties,the adjustability of degradation rate,and the improvement of biocompatibility,BMMCs reinforced with bioactive reinforcements have promising applications as a new generation of biomedical implants.In this review,the processing methods,Mg matrix,and reinforcement phases of BMMCs are discussed.Moreover,the review comprehensively discusses various BMMCs synthesized thus far,aiming to show the governing aspects of the achieved mechanical properties,corrosion behavior,and biocompatibility.Finally,this paper also discusses the research direction and further development areas for these materials.展开更多
Two new diterpenes, 15-ethyl-18-methyl pinifolate (1) and 18-hydroxy-labda-8(17),13E-dien-15-acetate (2), were isolated from the needles of Pinus sylvestris. Their structures were elucidated by spectroscopic methods, ...Two new diterpenes, 15-ethyl-18-methyl pinifolate (1) and 18-hydroxy-labda-8(17),13E-dien-15-acetate (2), were isolated from the needles of Pinus sylvestris. Their structures were elucidated by spectroscopic methods, including 2D-NMR spectra. Compound 1 exhibited the significant cytotoxic activity against the human carcinoma cell lines Hela, SK-N-SH and BEL-7402 in vitro.展开更多
Two new triterpenoids, 3β, 6β, 24-trihydroxyolean-12-en-27-oic acid and 3β-acetoxy- 6β*hydroxyurs-12-en-27-oic acid, as well as three known triterpenoids were isolated from the rhizomes of Astilbe chinensis. Their...Two new triterpenoids, 3β, 6β, 24-trihydroxyolean-12-en-27-oic acid and 3β-acetoxy- 6β*hydroxyurs-12-en-27-oic acid, as well as three known triterpenoids were isolated from the rhizomes of Astilbe chinensis. Their structures were elucidated by spectroscopic methods. These compounds showed Anti-cancer activities.展开更多
Three new cycloartane triterpene glycosides were isolated from the rhizomes of Actaea asiatica. Their structures were elucidated as 25-ethoxyl-cimigenol-3-O-β-D-xylopyranoside 1, 2'-O-acetyl soulieoside C 2, 2...Three new cycloartane triterpene glycosides were isolated from the rhizomes of Actaea asiatica. Their structures were elucidated as 25-ethoxyl-cimigenol-3-O-β-D-xylopyranoside 1, 2'-O-acetyl soulieoside C 2, 2'-O-acetyl cimiracemoside M 3.展开更多
Al-Mg alloys are an important class of non-heat treatable alloys in which Mg solute and grain size play essential role in their mechanical properties and plastic deformation behaviors.In this work,a cyclical continuou...Al-Mg alloys are an important class of non-heat treatable alloys in which Mg solute and grain size play essential role in their mechanical properties and plastic deformation behaviors.In this work,a cyclical continuous expanded extrusion and drawing(CCEED)process was proposed and implemented on an Al-3Mg alloy to introduce large plastic deformation.The results showed that the continuous expanded extrusion mainly improved the ductility,while the cold drawing enhanced the strength of the alloy.With the increased processing CCEED passes,the multi-pass cross shear deformation mechanism progressively improved the homogeneity of the hardness distributions and refined grain size.Continuous dynamic recrystallization played an important role in the grain refinement of the processed Al-3Mg alloy rods.Besides,the microstructural evolution was basically influenced by the special thermomechanical deformation conditions during the CCEED process.展开更多
The quenching-induced residual stress in ultrahigh strength Al-Zn-Mg-Cu alloys has a great influence on their precipitation behaviour in subsequent heat treatment and the properties of the final products.In the presen...The quenching-induced residual stress in ultrahigh strength Al-Zn-Mg-Cu alloys has a great influence on their precipitation behaviour in subsequent heat treatment and the properties of the final products.In the present work,the cladding quenching method was employed for 7085 Al alloy slabs to tailor different quenching residual stresses.Then the effects of quenching residual stress on the precipitation behaviour of the 7085 Al alloy were investigated through finite element analysis,residual stress and hardness distri-bution measurements and microstructural examinations.The results indicate that the reduction in resid-ual stress increases with increasing cladding layer thickness.For a cladding layer thickness in the range of 1-1.4 mm,the residual stress is almost eliminated.The hardness at the surface of the aged sample with a large compressive residual stress is decreased,while the hardness at the centre of the sample with a large tensile residual stress is increased.The hardness is approximately identical between the aged sam-ples with little or no residual stress.The elastic lattice distortion caused by residual stress is found to promote the nucleation of precipitates during the artificial ageing process.The in-depth mechanisms for the effect of quenching residual stress on the precipitation of 7085 Al alloy are also discussed.展开更多
The flow softening is an important phenomenon during hot deformation of metallic materials.In the present work,a more evident flow softening of Ti-6 Al-4 V alloy when deformed in two-phase region was observed in coars...The flow softening is an important phenomenon during hot deformation of metallic materials.In the present work,a more evident flow softening of Ti-6 Al-4 V alloy when deformed in two-phase region was observed in coarser a grain sample,which was attributed to an accelerated dynamic transformation from harder α phase into β phases.Notably,full β microstructure was observed in coarse grain samples at strain of 1.2,while retained a phase was observed in fine a grain specimens.In the views of thermodynamics and crystallographic analysis,the in-depth mechanisms of dynamic transformation were further investigated.展开更多
Three-dimensional(3D)graphene oxide-tris(4-aminophenyl)amine(GO-TAPAx:y)composites with different GO-to-TAPA mass ratios(x:y)were prepared by a facile one-step ultrasonic treatment.GOTAPAx:y composites were characteri...Three-dimensional(3D)graphene oxide-tris(4-aminophenyl)amine(GO-TAPAx:y)composites with different GO-to-TAPA mass ratios(x:y)were prepared by a facile one-step ultrasonic treatment.GOTAPAx:y composites were characterized by scanning electron microscopy(SEM),nitrogen(N2)adsorption-desorption isotherms,Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS)and thermogravimetric analysis(TGA).Behavior and mechanism of GO-TAPAx:yco mposites for the adsorption of rare earth elements(REEs)were investigated.The adso rption capacities of GO-TAPA1;2 composite for Yb^3+,Er^3+,Nd^3+,La^3+and Y^3+are 30.88,26.52,20.60,11.24 and 10.52 mg/g,respectively.Effects of some important parameters including GO-to-TAPA mass ratios,contact time,reaction temperature and initial Yb^3+concentration on the adsorption were evaluated in detail.FTIR spectral and XPS analyses show that the metal complexations and ion exchanges between nitrogen/oxygen-containing species of the adsorbents and REEs are involved in the adsorption procedure besides the conventional adsorption based on specific surface area,indicating the introduction of specific molecules onto GO is beneficial to its adsorption ability.The convenient reusability and applicability of GO-TAPAx:y composites toward real samples also demonstrate their feasibility in the enrichment of REE ions.展开更多
The hot deformation behavior of pure nickel with coarse, columnar grains in the temperature range of 950-1150 ℃ at intervals of 50℃ and in the strain rate range of 0.001-10.000 s^-1 at intervals of one order of magn...The hot deformation behavior of pure nickel with coarse, columnar grains in the temperature range of 950-1150 ℃ at intervals of 50℃ and in the strain rate range of 0.001-10.000 s^-1 at intervals of one order of magnitude was investigated by isothermal hot compressive testing with the compression ratio of 70%. The results reveal that the strain rate and the temperature strongly affect the flow stress during hot deformation and that flow stress increases with the increase in strain rate while decreases with temperature increasing. Moreover, the relationship among flow stress, strain rate and temperature can be represented by the Zener-Hollomon parameter with the calculated apparent activation energy of 312.403 kJ·mol^-1, and the variation of activation energy is sensitive to strain rate rather than temperature. In addition, the dynamic recrystallization (DRX) analysis reveals that the DRX behavior of nickel is evidently affected by both deformation temperature and strain rate and that the distinct mechanisms of nucleation are the bulging of serrated grain boundaries and the development of twinning.展开更多
The precipitation evolutions of Mg-Al-Zn alloys play essential roles in their mechanical properties,corrosion performance,formability,plastic deformation mechanisms and texture development.In the present work,the prec...The precipitation evolutions of Mg-Al-Zn alloys play essential roles in their mechanical properties,corrosion performance,formability,plastic deformation mechanisms and texture development.In the present work,the precipitation evolutions of AZ80 magnesium alloy during both non-isothermal and isothermal processes were unraveled by utilizing in situ electrical resistivity monitoring,hardness testing,differential scanning calorimetry and microstructural characterization.The results showed that discontinuous precipitation(DP)and continuous precipitation(CP)occurred competitively during non-isothermal and isothermal processes.The precipitation of dominantβ-Mg17 Al12 phase during non-isothermal processes was highly dependent on the thermal history.During isothermal processes,the precipitation behavior of AZ80 magnesium alloy could be considered as the functions of holding temperature and time.At lower temperatures,massive DP and CP were gradually formed to equally strengthen the alloy.At higher temperatures,the Ostwald coarsening was characterized in the later stages and indicated to slightly soften the alloy.Isothermal time-temperature-precipitation curves and quantitative precipitate evolution were estimated to unravel precipitation characteristics and their strengthening functions.展开更多
To date,the synthesis of crystalline ZnO nanostructures was often performed under high temperatures and/or high pressures with tiny output,which limits their commercial applications.Herein,we report the progress on sy...To date,the synthesis of crystalline ZnO nanostructures was often performed under high temperatures and/or high pressures with tiny output,which limits their commercial applications.Herein,we report the progress on synthesizing single-crystalline ZnO nanosheets under ambient conditions(i.e.,room temperature(RT)and atmospheric pressure)based on a sonochemistry strategy.Furthermore,their controllable growth is accomplished by adjusting the pH values of solutions,enabling the tailored crystal growth habits on the polar-charged faces of ZnO along c-axis.As a proof of concept for their potential applications,the ZnO nanosheets exhibit highly efficient performance for sensing ammonia at RT,with ultrahigh sensitivity(S=610 at 100 ppm),excellent selectivity,rapid detection(response time/recover time=70 s/4 s),and outstanding detection limit down to 0.5 ppm,superior to those of all pure ZnO nanostructures and most ZnO-based composite counterparts ever reported.The present work might open a door for controllable production of ZnO nanostructures under mild conditions,and facilitate the exploration of modern gas sensors for detecting gaseous molecules at RT,which underscores their potential toward practical applications in opto-electronic nanodevices.展开更多
基金supported by the National Natural Science Foundation of China(51774124,52074114)Hunan Provincial Natural Science Foundation of China(2019JJ40017,2020JJ5062)+1 种基金Key Technologies R&D in Strategic Emerging Industries and Transformation in High-tech Achievements Program of Hunan Province(2019GK4045)Graduate Training and Innovation Practice Base of Hunan Province.
文摘Despite the industrial significance of grain size for enhancing mechanical properties and formability,the in-depth deformation mechanisms at elevated temperature are still unclear.To investigate the functions of grain size on hot workability and deformation mechanisms,three groups of Mg-1.2Zn-0.2Y alloy specimens with different grain sizes were hot compressed and then studied by combining constitutive model,processing map and microstructural observations.The results showed that the enhanced hot workability accompanying low deformation activation energy and small instability regime was obtained with refined grain size.During hot deformation,the decreased grain size in Mg1.2Zn-0.2Y alloy mainly improved the plastic deformation homogeneity,especially for the weakened local straining around grain boundaries.As a result,the dynamic recrystallization nucleation and texture development at lower strain level were influenced by the initial grain size.At higher strain magnitude,the growth and coarsening of dynamic recrystallized grains would further release strain localization and improve hot workability,while the texture was less impacted.Further,unlike the primary basal slip and deformation twinning in the specimen with coarse grain at low temperature,non-basal slips of dislocations were initiated with less deformation twins in the specimens with refined grain size.
基金the National Natural Science Foundation of China(NSFC,Grant No.51972178)the Natural Science Foundation of Ningbo(2022J139)the Ningbo Yongjiang Talent Introduction Programme(2022A-227-G).
文摘Two-dimensional(2D)oxides have been the focus of substantial research interest recently,owing to their fascinating physico-chemical properties.However,fabrication of large-area 2D oxide materials in a controlled manner under mild conditions still remains a formidable challenge.Herein,we develop a facile and universal strategy based on the sonochemistry approach for controllable and large-area growth of quasi-aligned single-crystalline ZnO nanosheets on a Zn substrate(Zn@SC-ZnO)under ambient conditions.The obtained ZnO nanosheets possess the desired exclusively exposed(001)facets,which have been confirmed to play a critical role in significantly reducing the activation energy and facilitating the stripping/plating processes of Zn.Accordingly,the constructed Zn@SC-ZnO||Zn@SC-ZnO symmetric cell has very low polarization overpotential down to~20 mV,with limited dendrite growth and side reactions for Zn anodes.The developed Zn@SC-ZnO//MnO_(2)aqueous Zn-ion batteries(ZIBs)show a voltage efficiency of 88.2%under 500 mA g^(-1)at the stage of 50%depth of discharge,which is state of the art for ZIBs reported to date.Furthermore,the as-assembled large-size cell(5 cm×5 cm)delivers an open circuit potential of 1.648 V,and can be robustly operated under a high current of 20 mA,showing excellent potential for future scalable applications.
基金Hunan Provincial Innovation Foundation for Postgraduate,Grant/Award Number:CX20200454National Natural Science Foundation of China,Grant/Award Number:51972178。
文摘We report the scalable fabrication of CdS/ZnS 1D/2D heterojunctions under ambient air conditions(i.e.,room temperature and atmospheric pressure)in which ZnS nanoparticles are anchored on the surface of CdS nanosheets.The as-formed heterojunctions exhibit a significantly enhanced photocatalytic H_(2) evolution rate of 14.02 mmol h^(-1) g^(-1) when irradiated with visible light,which is~10 and 85 times higher than those of pristine CdS nanosheets and CdS nanoparticles,respectively,and superior to most of the CdS-based photocatalysts reported to date.Furthermore,they provide robust photocatalytic performance with demonstratable stability over 58 h,indicating their potential for practical applications.The formation of 1D/2D heterojunctions not only provides improved exposed active sites that respond to illumination but also provides a rapid pathway to generate photogenerated carriers for efficient separation and transfer through the matrix of single-crystalline CdS nanosheets.In addition,first-principles simulations demonstrate that the existence of rich Zn vacancies increases the energy level of the ZnS valence band maximum to construct type-II and Z-scheme mixed heterojunctions,which plays a critical role in suppressing the recombination of carriers with limited photocorrosion of CdS to enhance photocatalytic behavior.
文摘The linkage between Qi and mitochondria was investigated by exploring the effect of Traditional Chinese Medicine (TCM) Qi-invigorating herbs on mitochondrial function at the biochemical and molecular levels. Three Chinese herbs (<i></span><i><span style="font-family:Verdana;">Astragali radix</span></i><span style="font-family:Verdana;">,</span><i><span style="font-family:Verdana;"> Herba cistanche</span></i><span style="font-family:Verdana;">, </span><i><span style="font-family:Verdana;">Panax ginseng</span></i><span style="font-family:Verdana;"></i>) were used to treat cultured mouse kidney cells and the generation of adenosine triphosphate (ATP) was measured. The Qi-invigorating herb, <i></span><i><span style="font-family:Verdana;">Astragali radix</span></i><span style="font-family:Verdana;"></i>, was selected for further </span></span><span style="font-family:""><span style="font-family:Verdana;">study using additional biological and molecular parameters, including ATP, reactive oxygen species (ROS), mitochondrial membrane potential (MMP),</span><span><span style="font-family:Verdana;"> mtDNA copies, superoxide dismutase (SOD), glutathione (GSH), cell growth, cell viability and transcriptomes. We also chose two concentrations of <i></span><i><span style="font-family:Verdana;">Astragali radix</span></i><span style="font-family:Verdana;"></i> to study the hormetic effect. The results indicated that: 1) Qi-invigorating herbs have significant effects on the function of mitochondria, with ATP production and the antioxidant capacity being significantly enhanced, and ROS le</span></span><span style="font-family:Verdana;">vels being reduced, allowing for a more optimal oxidation environment. The effect of the herbs followed a hormetic curve with a stimulating effect at lower</span><span> </span><span style="font-family:Verdana;">doses but an inhibiting effect at high doses;2) The growth of the cells was not</span><span> </span><span style="font-family:Verdana;">affected despite numerous biochemical changes associated with mitochondrial</span><span> </span><span style="font-family:Verdana;">function, indicating the powerful ability of mitochondria to maintain cellular homeostasis;3) The up-regulation of NOCT gene, related to nicotinamide adenine dinucleotide (NADH) synthesis, offers a molecular basis for the ATP-promoting effect of the Qi-invigorating herbs. This work provides additional insight into the efficacy of TCM herbs from a western perspective.
文摘<i><span style="font-family:Verdana;">Objectives</span></i><span style="font-family:Verdana;"></i>: To explore the effects of Qi-invigorating herbs on mitochondrial function using cultured cells and animal organs. <i></span><i><span style="font-family:Verdana;">Methods</span></i><span style="font-family:Verdana;"></i>: Using water extracts of <i></span><i><span style="font-family:Verdana;">Astragali radix</span></i><span style="font-family:Verdana;"></i>, we investigated the effect of “Qi-invigoration” on M-1 renal cells and mouse organs <i></span><i><span style="font-family:Verdana;">in-vitro</span></i><span style="font-family:Verdana;"></i> including total adenylate production (TAP), reactive oxygen species (ROS) levels, and mitochondrial membrane potential (MMP). We also examined the effect on antioxidant capacity by conducting an analysis of superoxide dismutase (SOD) and glutathione (GSH). <i></span><i><span style="font-family:Verdana;">Results</span></i><span style="font-family:Verdana;"></i>: 1) <i></span><i><span style="font-family:Verdana;">Astragali radix</span></i><span style="font-family:Verdana;"></i> increased mitochondrial TAP generation and decreased ROS levels in both mouse kidney tissues and M-1 renal cells. 2) <i></span><i><span style="font-family:Verdana;">Astragali radix</span></i><span style="font-family:Verdana;"></i> also significantly increased MMP and GSH levels in M-1 cells, but in the kidney tissue</span><span style="font-family:Verdana;">,</span><span style="font-family:""><span style="font-family:Verdana;"> there was no significant change in MMP levels and a decrease in GSH levels. 3) <i></span><i><span style="font-family:Verdana;">Astragali radix</span></i><span style="font-family:Verdana;"></i> stimulated TAP levels in the heart, spleen, lung, kidney and skeletal muscle tissue, which was accompanied by the reduction of ROS. 4) For the meridian organs that <i></span><i><span style="font-family:Verdana;">Astragali radix</span></i><span style="font-family:Verdana;"></i> belongs to, the energy production and antioxidant capacity were boosted simultaneously. <i></span><i><span style="font-family:Verdana;">Conclusions</span></i><span style="font-family:Verdana;"></i>: These results provide new insights for the biochemical </span><span style="font-family:Verdana;">b</span><span style="font-family:Verdana;">asis of Qi-invigoration and the meridian tropism theory for this Qi-invigora</span><span style="font-family:Verdana;">ting herb.</span></span>
文摘<i><span style="font-family:Verdana;">Astragali Radix </span></i><span style="font-family:Verdana;">(AR), the dried root of legumes, belongs to the Qi-invigorating</span><span style="font-family:""> <span style="font-family:Verdana;">herbs in traditional Chinese medicine and plays an important role in the</span><span style="font-family:Verdana;"> treatment of many diseases. In order to understand the mechanism of action of AR extract. We used AR extract to treat M-1, mouse kidney cells, and used transcriptome sequencing technology to detect the genomic transcription level of the cells under the action of AR at different concentrations and times. The results showed that after a low concentration of AR treatments on the cells, the expression of genes related to cell growth and cellular immune response changed significantly, among which multiple genes are related to mitochondrial function, while high concentrations of AR affected the expression of histones and disease-related genes. It showed that the low concentration of AR extract can achieve the effect of invigorating Qi by regulating the function of mitochondria. In addition, several important genes and pathways were identified as potential targets of AR activation. The research not only clarified the main molecular biological mechanism of AR invigorating Qi, but also provided experimental basis and cellular physiology reference for the further clinical application of AR.
基金Project(51904099)supported by the National Natural Science Foundation of ChinaProject(531118010353)supported by the Fundamental Research Funds for the Central Universities,China。
基金financially supported by the National Natural Science Foundation of China (Nos. 51574118, 51571087, 51674292)the Natural Science Foundation of Hunan Province (No. 2015JJ4017)+1 种基金the Project of Innovation-driven Plan in Central South University (No. 2016CX007)the Hunan Provincial Science and Technology Plan Project, China (No. 2016TP1007)
文摘Graphene-reinforced aluminum(Al) matrix composites were successfully prepared via solution mixing and powder metallurgy in this study. The mechanical properties of the composites were studied using microhardness and tensile tests. Compared to the pure Al alloy, the graphene/Al composites showed increased strength and hardness. A tensile strength of 255 MPa was achieved for the graphene/Al composite with only 0.3 wt% graphene, which has a 25% increase over the tensile strength of the pure Al matrix. Raman spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy were used to investigate the morphologies, chemical compositions, and microstructures of the graphene and the graphene/Al composites. On the basis of fractographic evidence, a relevant fracture mechanism is proposed.
基金the National Natural Science Foundation of China(Nos.51574118 and51674118)。
文摘Biodegradable magnesium alloys as new biomedical implant materials have been extensively studied because of their notable biodegradability over traditional bio-inert metals.However,the extreme degradation rate of pure magnesium leads to the loss of its mechanical integrity before the tissue recovers completely.The solutions to this challenge are as follows:(1)purification,(2)alloying,(3)surface modification,and(4)biodegradable magnesium-matrix composites(BMMCs)synthesis.Owing to the tunability of mechanical properties,the adjustability of degradation rate,and the improvement of biocompatibility,BMMCs reinforced with bioactive reinforcements have promising applications as a new generation of biomedical implants.In this review,the processing methods,Mg matrix,and reinforcement phases of BMMCs are discussed.Moreover,the review comprehensively discusses various BMMCs synthesized thus far,aiming to show the governing aspects of the achieved mechanical properties,corrosion behavior,and biocompatibility.Finally,this paper also discusses the research direction and further development areas for these materials.
文摘Two new diterpenes, 15-ethyl-18-methyl pinifolate (1) and 18-hydroxy-labda-8(17),13E-dien-15-acetate (2), were isolated from the needles of Pinus sylvestris. Their structures were elucidated by spectroscopic methods, including 2D-NMR spectra. Compound 1 exhibited the significant cytotoxic activity against the human carcinoma cell lines Hela, SK-N-SH and BEL-7402 in vitro.
文摘Two new triterpenoids, 3β, 6β, 24-trihydroxyolean-12-en-27-oic acid and 3β-acetoxy- 6β*hydroxyurs-12-en-27-oic acid, as well as three known triterpenoids were isolated from the rhizomes of Astilbe chinensis. Their structures were elucidated by spectroscopic methods. These compounds showed Anti-cancer activities.
文摘Three new cycloartane triterpene glycosides were isolated from the rhizomes of Actaea asiatica. Their structures were elucidated as 25-ethoxyl-cimigenol-3-O-β-D-xylopyranoside 1, 2'-O-acetyl soulieoside C 2, 2'-O-acetyl cimiracemoside M 3.
基金This work was financially supported by the National Nat-ural Science Foundation of China(No.51774124)the Hun-an Provincial Natural Science Foundation of China(No.2019JJ40017)+1 种基金the Key Technologies R&D in Strategic Emerging Industries and Transformation in High-tech Achievements Program of Hunan Province,China(No.2019GK4045)the Graduate Training and Innovation Practice Base of Hunan Province,China.
文摘Al-Mg alloys are an important class of non-heat treatable alloys in which Mg solute and grain size play essential role in their mechanical properties and plastic deformation behaviors.In this work,a cyclical continuous expanded extrusion and drawing(CCEED)process was proposed and implemented on an Al-3Mg alloy to introduce large plastic deformation.The results showed that the continuous expanded extrusion mainly improved the ductility,while the cold drawing enhanced the strength of the alloy.With the increased processing CCEED passes,the multi-pass cross shear deformation mechanism progressively improved the homogeneity of the hardness distributions and refined grain size.Continuous dynamic recrystallization played an important role in the grain refinement of the processed Al-3Mg alloy rods.Besides,the microstructural evolution was basically influenced by the special thermomechanical deformation conditions during the CCEED process.
基金supported by the Nation Natural Science Foun-dation of China(No.51874127)Postgraduate Scientific Re-search Innovation Project of Hunan Province(No.CX20210403).
文摘The quenching-induced residual stress in ultrahigh strength Al-Zn-Mg-Cu alloys has a great influence on their precipitation behaviour in subsequent heat treatment and the properties of the final products.In the present work,the cladding quenching method was employed for 7085 Al alloy slabs to tailor different quenching residual stresses.Then the effects of quenching residual stress on the precipitation behaviour of the 7085 Al alloy were investigated through finite element analysis,residual stress and hardness distri-bution measurements and microstructural examinations.The results indicate that the reduction in resid-ual stress increases with increasing cladding layer thickness.For a cladding layer thickness in the range of 1-1.4 mm,the residual stress is almost eliminated.The hardness at the surface of the aged sample with a large compressive residual stress is decreased,while the hardness at the centre of the sample with a large tensile residual stress is increased.The hardness is approximately identical between the aged sam-ples with little or no residual stress.The elastic lattice distortion caused by residual stress is found to promote the nucleation of precipitates during the artificial ageing process.The in-depth mechanisms for the effect of quenching residual stress on the precipitation of 7085 Al alloy are also discussed.
基金supported financially by the National Natural Science Foundation of China(Nos.51674111 and 51874127)the Chinese Scholarship Council(No.CSC 201606130102)。
文摘The flow softening is an important phenomenon during hot deformation of metallic materials.In the present work,a more evident flow softening of Ti-6 Al-4 V alloy when deformed in two-phase region was observed in coarser a grain sample,which was attributed to an accelerated dynamic transformation from harder α phase into β phases.Notably,full β microstructure was observed in coarse grain samples at strain of 1.2,while retained a phase was observed in fine a grain specimens.In the views of thermodynamics and crystallographic analysis,the in-depth mechanisms of dynamic transformation were further investigated.
基金Project supported by National Natural Science Foundation of China(51674292)Fundamental Research Funds for the Central Universities of Central South University(2019zzts434)。
文摘Three-dimensional(3D)graphene oxide-tris(4-aminophenyl)amine(GO-TAPAx:y)composites with different GO-to-TAPA mass ratios(x:y)were prepared by a facile one-step ultrasonic treatment.GOTAPAx:y composites were characterized by scanning electron microscopy(SEM),nitrogen(N2)adsorption-desorption isotherms,Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS)and thermogravimetric analysis(TGA).Behavior and mechanism of GO-TAPAx:yco mposites for the adsorption of rare earth elements(REEs)were investigated.The adso rption capacities of GO-TAPA1;2 composite for Yb^3+,Er^3+,Nd^3+,La^3+and Y^3+are 30.88,26.52,20.60,11.24 and 10.52 mg/g,respectively.Effects of some important parameters including GO-to-TAPA mass ratios,contact time,reaction temperature and initial Yb^3+concentration on the adsorption were evaluated in detail.FTIR spectral and XPS analyses show that the metal complexations and ion exchanges between nitrogen/oxygen-containing species of the adsorbents and REEs are involved in the adsorption procedure besides the conventional adsorption based on specific surface area,indicating the introduction of specific molecules onto GO is beneficial to its adsorption ability.The convenient reusability and applicability of GO-TAPAx:y composites toward real samples also demonstrate their feasibility in the enrichment of REE ions.
基金financially supported by the National Natural Science Foundation of China (Nos. 51271076 and 51474101)
文摘The hot deformation behavior of pure nickel with coarse, columnar grains in the temperature range of 950-1150 ℃ at intervals of 50℃ and in the strain rate range of 0.001-10.000 s^-1 at intervals of one order of magnitude was investigated by isothermal hot compressive testing with the compression ratio of 70%. The results reveal that the strain rate and the temperature strongly affect the flow stress during hot deformation and that flow stress increases with the increase in strain rate while decreases with temperature increasing. Moreover, the relationship among flow stress, strain rate and temperature can be represented by the Zener-Hollomon parameter with the calculated apparent activation energy of 312.403 kJ·mol^-1, and the variation of activation energy is sensitive to strain rate rather than temperature. In addition, the dynamic recrystallization (DRX) analysis reveals that the DRX behavior of nickel is evidently affected by both deformation temperature and strain rate and that the distinct mechanisms of nucleation are the bulging of serrated grain boundaries and the development of twinning.
基金the National Natural Science Foundation of China(52074114)the Hunan Provincial Innovation Foundation for Post graduate(CX20190314)。
文摘The precipitation evolutions of Mg-Al-Zn alloys play essential roles in their mechanical properties,corrosion performance,formability,plastic deformation mechanisms and texture development.In the present work,the precipitation evolutions of AZ80 magnesium alloy during both non-isothermal and isothermal processes were unraveled by utilizing in situ electrical resistivity monitoring,hardness testing,differential scanning calorimetry and microstructural characterization.The results showed that discontinuous precipitation(DP)and continuous precipitation(CP)occurred competitively during non-isothermal and isothermal processes.The precipitation of dominantβ-Mg17 Al12 phase during non-isothermal processes was highly dependent on the thermal history.During isothermal processes,the precipitation behavior of AZ80 magnesium alloy could be considered as the functions of holding temperature and time.At lower temperatures,massive DP and CP were gradually formed to equally strengthen the alloy.At higher temperatures,the Ostwald coarsening was characterized in the later stages and indicated to slightly soften the alloy.Isothermal time-temperature-precipitation curves and quantitative precipitate evolution were estimated to unravel precipitation characteristics and their strengthening functions.
基金This work was supported by the National Natural Science Foundation of China(Grant No.51972178)Hunan Provincial Innovation Foundation for Postgraduate(Grant No.CX20200454).
文摘To date,the synthesis of crystalline ZnO nanostructures was often performed under high temperatures and/or high pressures with tiny output,which limits their commercial applications.Herein,we report the progress on synthesizing single-crystalline ZnO nanosheets under ambient conditions(i.e.,room temperature(RT)and atmospheric pressure)based on a sonochemistry strategy.Furthermore,their controllable growth is accomplished by adjusting the pH values of solutions,enabling the tailored crystal growth habits on the polar-charged faces of ZnO along c-axis.As a proof of concept for their potential applications,the ZnO nanosheets exhibit highly efficient performance for sensing ammonia at RT,with ultrahigh sensitivity(S=610 at 100 ppm),excellent selectivity,rapid detection(response time/recover time=70 s/4 s),and outstanding detection limit down to 0.5 ppm,superior to those of all pure ZnO nanostructures and most ZnO-based composite counterparts ever reported.The present work might open a door for controllable production of ZnO nanostructures under mild conditions,and facilitate the exploration of modern gas sensors for detecting gaseous molecules at RT,which underscores their potential toward practical applications in opto-electronic nanodevices.
