The renowned scientist is academician of the Chinese Academy of Sciences,former president of Tsinghua University,and chair of the Tengchong Scientists Forum.ACADEMICIAN of the Chinese Academy of Sciences,former presid...The renowned scientist is academician of the Chinese Academy of Sciences,former president of Tsinghua University,and chair of the Tengchong Scientists Forum.ACADEMICIAN of the Chinese Academy of Sciences,former president of Tsinghua University,and chair of the Tengchong Scientists Forum,Gu Binglin is one of the world’s top physicists and materials scientist,and a pioneer in the field of materials design.展开更多
Organic nanophotocatalysts are promising candidates for solar fuels production,but they still face the challenge of unfavorable geminate recombination due to the limited exciton diffusion lengths.Here,we introduce a b...Organic nanophotocatalysts are promising candidates for solar fuels production,but they still face the challenge of unfavorable geminate recombination due to the limited exciton diffusion lengths.Here,we introduce a binary nanophotocatalyst fabricated by blending two polymers,PS-PEG5(PS)and PBT-PEG5(PBT),with matched absorption and emission spectra,enabling a Forster resonance energy transfer(FRET)process for enhanced photocatalysis.These heterostructure nanophotocatalysts are processed using a facile and scalable flash nanoprecipitation(FNP)technique with precious kinetic control over binary nanoparticle formation.The resulting nanoparticles exhibit an exceptional photocatalytic hydrogen evolution rate up to 65 mmol g^(-1) h^(-1),2.5 times higher than that single component nanoparticles.Characterizations through fluorescence spectra and transient absorption spectra confirm the hetero-energy transfer within the binary nanoparticles,which prolongs the excited-state lifetime and extends the namely“effective exciton diffusion length”.Our finding opens new avenues for designing efficient organic photocatalysts by improving exciton migration.展开更多
Background: Chronic low back pain is a leading cause of morbidity and disability globally. Low and Middle-Income Countries (LMICs) tend to be more affected, with chronic low back pain (CLBP) being among the leading pr...Background: Chronic low back pain is a leading cause of morbidity and disability globally. Low and Middle-Income Countries (LMICs) tend to be more affected, with chronic low back pain (CLBP) being among the leading presenting complaints at specialist consultation. The exact burden of this disease is sparingly known in our setting. Objective: To evaluate the burden of chronic low back pain at the Yaounde Central Hospital. Methods: This was a descriptive cross-sectional study for a period of 3 months, from March 2022 to May 2022. After obtaining ethical clearance and research authorisations, data was collected using structured questionnaires from patients with chronic low back pain presenting at the Yaounde Central Hospital during the aforementioned time frame. This data was then tabulated with the Statistical Package for Social Sciences (SPSS 23.0), and disability was assessed using the modified Roland Morris Disability Questionnaire and the Oswestry Disability Index. Data analysis was done using the International Business Machines Statistical Package for Social Sciences (IBM-SPSS) VERSION 23.0. Results: 115 cases of CLBP were included. The mean age was 52.62 years, and the sex ratio was 0.3. The average monthly income was less than 50,000 frs CFA, in 37.4% of cases. In 57.9%, patients had a job that involved physical labour. The patients had a secondary level of education in 40.9%, and alcohol consumption was observed in 36%. The average number of days of a work stoppage due to LBP was 12.75 days (±12SD), and the median duration of CLBP was 7.15 (7.5SD) years. The median pain intensity was 7 (±2SD), with leg pain and sensory neuropathy observed in 67.8% and 63.5% respectively. Lumbar X-ray was done in 45.2% and revealed lumbar osteoarthrosis in 62.4%. Hypertension as a comorbidity was observed in 26.1%. Medical treatment was used at least once in 98.3% of cases. The average cost of management per month was assessed, and the median was 52,000 FCFA (±20,876 SD). Using the Oswestry Disability Questionnaire, 46 patients, that is 40% of the study population, were classified as severely disabled with a median ODI score of 40%. The factors which were independently associated with disability were level of education, alcohol consumption, treatment modality, pain intensity, body mass index (BMI), psychological wellbeing and number of sick leave days. Conclusion: Chronic low back pain is common in our setting. There is a female predominance with the mean age of the study population situated in the 5th decade. Low-income earners and patients with a job involving physical labour were the most affected. Medical treatment was the main therapeutic modality, with the average cost of management per month being above the average monthly income of the greater majority of the patients. Several factors influenced disability, some of which were independently associated with it, such as level of education, alcohol consumption and treatment modality.展开更多
The International Health Regulations(IHR)of the republic of South Africa confirmed 20 human monkeypox(mpox)cases including the death of 3 individuals to the World Health Organization(WHO)between 8 May and 2 July 2024....The International Health Regulations(IHR)of the republic of South Africa confirmed 20 human monkeypox(mpox)cases including the death of 3 individuals to the World Health Organization(WHO)between 8 May and 2 July 2024.All the cases were men aged between 17 and 43 years and 11 were men who have sex with men.Out of these cases,15 cases were living with un-managed or recently diagnosed HIV infection.All these cases were symptomatic with extensive skin lesions and required hospitalization.This sudden incidence of mpox cases without any prior history of international travel,high prevalence of HIV and high case fatality ratio,suggests that the community transmission is still prevalent.Rise of mpox cases in vulnerable groups in South Africa has the potential for increased health impact in people living in neighboring countries and has the risk of cross border and international spread.Due to this reason,national health authorities in South Africa have initiated various response measures with the support from the WHO to control this infection[1].展开更多
Singlet oxygen(^(1)O_(2)),as the primary reactive oxygen species in photodynamic therapy,can effectively induce excessive oxidative stress to ablate tumors and kill germs in clinical treatment.However,monitoring endog...Singlet oxygen(^(1)O_(2)),as the primary reactive oxygen species in photodynamic therapy,can effectively induce excessive oxidative stress to ablate tumors and kill germs in clinical treatment.However,monitoring endogenous^(1)O_(2)is greatly challenging due to its extremely short lifetime and high reactivity in biological condition.Herein,we report an ultra-high signal-to-ratio near-infrared chemiluminescent probe(DCMCy)for the precise detection of endogenous^(1)O_(2)during photodynamic therapy(PDT).The methoxy moiety was removed from enolether unit in DCM-Cy to suppress the potential self-photooxidation reaction,thus greatly eliminating the photoinduced background signals during PDT.Additionally,the compact cyclobutane modification of DCM-Cy resulted in a significant 6-fold increase in cell permeability compared to conventional adamantane-dioxane probes.Therefore,our“step-by-step”strategy for DCM-Cy addressed the limitations of traditional chemiluminescent(CL)probes for^(1)O_(2),enabling effectively tracking of endogenous^(1)O_(2)level changes in living cells,pathogenic bacteria and mice in PDT.展开更多
Icing detection is critically important for preventing safety accidents and economic losses,especially concerning ice formation from invalidated anti-icing fluids(water and ethylene glycol)under extreme conditions.Tra...Icing detection is critically important for preventing safety accidents and economic losses,especially concerning ice formation from invalidated anti-icing fluids(water and ethylene glycol)under extreme conditions.Traditional technologies like ultrasonics and capacitor-antenna face challenges with limited detection areas,lower accuracy,and susceptibility to electromagnetic interference.Here,we introduce a novel viscosity-ultrasensitive fluorescent probe 40,4‴-(2,2-diphenyle-thene-1,1-diyl)bis-(3,5-dicarboxylate)(TPE-2B4C)based on AIEgens for moni-toring ice formation of anti-icing fluids in low-temperature environments.TPE-2B4C,consisting of four sodium carboxylate groups and multiple freely rotating benzene rings,demonstrates outstanding solubility in anti-icing fluids and exhibits no fluorescent background signal even at low temperatures(<−20°C).Upon freezing,TPE-2B4C relocates from the water phase to higher viscosity ethylene glycol,causing restriction of benzene rings and a significantly increased green fluorescence signal.TPE-2B4C can successfully determine whether the anti-icing fluids are icing from−5 to−20°C with a high contrast ratio.Due to its simple setup,fast operation,and broad applicability,our new method is anticipated to be employed for rapid,real-time,and large-scale icing detection.展开更多
The development of high-performance,reproducible carbon(C)-based supercapacitors remains a significant challenge because of limited specific capacitance.Herein,we present a novel strategy for fabricating LaCoO_(x) and...The development of high-performance,reproducible carbon(C)-based supercapacitors remains a significant challenge because of limited specific capacitance.Herein,we present a novel strategy for fabricating LaCoO_(x) and cobalt(Co)-doped nanoporous C(LaCoO_(x)/Co@ZNC)through the carbonization of Co/Zn-zeolitic imidazolate framework(ZIF)crystals derived from a PVP-Co/Zn/La precursor.The unique ZIF structure effectively disrupted the graphitic C framework,preserved the Co active sites,and enhanced the electrical conductivity.The synergistic interaction between pyridinic nitrogen and Co ions further promoted redox reactions.In addition,the formation of a hierarchical pore structure through zinc sublimation facili-tated electrolyte diffusion.The resulting LaCoO_(x)/Co@ZNC exhibited exceptional electrochemical performance,delivering a remarkable specific capacitance of 2,789 F/g at 1 A/g and outstanding cycling stability with 92%capacitance retention after 3,750 cycles.Our findings provide the basis for a promising approach to advancing C-based energy storage technologies.展开更多
A combination of hard(SiCP)and soft(fly ash)particulate reinforcements could be a strategy to enhance combination of multiple properties of Magnesium and its alloys which otherwise suffer from low stiffness,low wear r...A combination of hard(SiCP)and soft(fly ash)particulate reinforcements could be a strategy to enhance combination of multiple properties of Magnesium and its alloys which otherwise suffer from low stiffness,low wear resistance,and many other critical properties.However,at present a comprehensive and robust map correlating different properties in particle-reinforced composites is much lacking.In this work,an industrial grade AZ91 magnesium alloy reinforced with hard SiC and soft fly ash particles(with 3 vol.%each),has been prepared using stir casting followed by hot extrusion at 325℃with a ratio of 21.5.Microstructure of the hybrid composite was characterized using optical and scanning electron microscopes.The composite exhibited a reduction in average grain size from 13.6 to 7.1μm,concomitantly an increase in Vickers hardness from 73 to 111 HV.The tension-compression yield asymmetry ratios of the unreinforced alloy and hybrid composite were 1.165 and 0.976,respectively indicating higher yield strength for the composite under compressive load.The composite exhibited 76%improvement in damping capacity under time sweep mode,and 28%improvement at 423 K under temperature sweep mode.The tribological characteristics of the composite under dry sliding conditions at sliding speeds and loads in the range of 0.5 to 1.5 m s^(-1)and 10 to 30 N,respectively showed higher wear resistance than the unreinforced alloy.The composite showed 23%improvement in sliding wear resistance at a load of 20 N and a speed of 1 m s^(-1).Finally,efforts have been made to understand the influence of one property on the other by developing statistical property correlation maps from the properties obtained in this study and from the literature.These maps are expected to help in the design of hybrid Metal Matrix Composites for a variety of targeted applications in different sectors.展开更多
H_(2)O_(2)is an environmentally friendly oxidizing agent with minimal secondary pollution;however,its application has always been constrained by factors such as storage and transportation.In this study,we propose an i...H_(2)O_(2)is an environmentally friendly oxidizing agent with minimal secondary pollution;however,its application has always been constrained by factors such as storage and transportation.In this study,we propose an innovative method for storing and releasing H_(2)O_(2)using hydrogels.Commercial hydrogels(sodium polyacrylate)can undergo swelling and absorb H_(2)O_(2)in aqueous solutions,and the swollen hydrogel can continuously release H_(2)O_(2)under osmotic pressure.And the characteristics of osmotic pressure drive ensure the recyclability of hydrogel for H_(2)O_(2)storage.Experimental results demonstrate that H_(2)O_(2)can stably exist within the hydrogel for an extended period,and this strategy helps to avoid explosion the risk and potential environmental hazards during the transportation of H_(2)O_(2).Finally,experiments confirm that the hydrogel controlled sustained release of H_(2)O_(2)is effective in both Fenton reactions and the process of bacterial inactivation.This work introduces new ideas for the storage of H_(2)O_(2),and the sustained release of H_(2)O_(2)may have significant implications in the fields of healthcare,environmental science,catalysis,and beyond.展开更多
Modeling the boundary layer flow of ternary hybrid nanofluids is important for understanding and optimizing their thermal performance,particularly in applications where enhanced heat transfer and fluid dynamics are es...Modeling the boundary layer flow of ternary hybrid nanofluids is important for understanding and optimizing their thermal performance,particularly in applications where enhanced heat transfer and fluid dynamics are essential.This study numerically investigates the boundary layer flow of alumina-copper-silver/water nanofluid over a permeable stretching/shrinking sheet,incorporating both first and second-order velocity slip.The mathematical model is solved in MATLAB facilitated by the bvp4c function that employs the finite difference scheme and Lobatto IIIa formula.The solver successfully generates dual solutions for the model,and further analysis is conducted to assess their stability.The findings reported that only one of the solutions is stable.For the shrinking sheet case,increasing the first-order velocity slip delays boundary layer separation and enhances heat transfer,while,when the sheet is stretched,the second-order velocity slip accelerates separation and improves heat transfer.Boundary layer separation is most likely to occur when the sheet is shrinking;however,this can be controlled by adjusting the velocity slip with the inclusion of boundary layer suction.展开更多
Pd-based catalysts have been extensively studied in the catalytic oxidation of methane,but their longterm stability and water resistance are unsatisfactory as the active sites are susceptible to water toxicity.The add...Pd-based catalysts have been extensively studied in the catalytic oxidation of methane,but their longterm stability and water resistance are unsatisfactory as the active sites are susceptible to water toxicity.The addition of Pt to Pd-based catalysts is found to be the most effective and promising method.However,distinct states of existence of Pt can affect the catalytic performance to different degrees,even negatively.Therefore,the impact mechanism of Pt on Pd-based catalysts needs to be further understood.In this work,A-site defective La_(0.9)AlO_(x)perovskite was used as a support,and the state of Pt in catalysts was regulated by adjusting the introducing sequence of Pd and Pt,It is found that only when Pt is introduced preferentially,the activity and water resistance of the bimetal can be improved.Combining a series of characterization results of the fresh catalysts,reduced catalysts,and the samples after reduction and use,it is found that the higher Pt^(2+)content in the catalyst is the main reason for promoting bimetallic properties,while more Pt0has an inhibitory effect.This work provides a new understanding of the promotion effect of Pt on Pd-Pt bimetal in the catalytic oxidation reaction of methane.展开更多
The development of efficient aggregation-induced emission(AIE)active probes is crucial for disease diagnosis,particularly for tumors and cardiovascular diseases.Current AIE-active probes primarily focus on improving t...The development of efficient aggregation-induced emission(AIE)active probes is crucial for disease diagnosis,particularly for tumors and cardiovascular diseases.Current AIE-active probes primarily focus on improving their water solubility to resist aggregation,thereby achieving an initial fluorescence-off state.However,the complex biological environment can cause undesirable aggregation,resulting in false signals.To address this issue,we have ingeniously introduced an azo group into the AIE luminogen(AIEgen),developing a reductase-activated AIE probe,Azo-quinoline-malononitrile(QM)-PN,for imaging hypoxic environments.In this probe,the azo group promotes intramolecular motion through rapid E/Z isomerization,causing the excited state energy to dissipate via non-radiative decay,thus turning off the initial fluorescence.In the presence of reductase,Azo-QM-PN is reduced and cleaved to produce the hydrophobic AIEgen NH_(2)-QM-PN,which subsequently aggregates and generates an in situ AIE signal,thereby imaging the hypoxic environment with reductase.Encapsulation of Azo-QM-PN with DSPEPEG2000 results in the formation of the nanoprobe Azo-QM-PN NPs,which can effectively penetrate cell membranes,specifically illuminate tumor cells,monitor fluctuations in azo reductase levels,and deeply penetrate and image multicellular tumor spheroids,demonstrating potential for hypoxic tumor imaging.Additionally,the nanoprobe Azo-QM-PN NPs can selectively image hypoxic atherosclerotic plaque tissues,showing potential for detecting atherosclerosis.Therefore,in this study,we successfully developed an enzyme-activated AIE probe for imaging hypoxic environments,laying the foundation for further clinical applications.展开更多
文摘The renowned scientist is academician of the Chinese Academy of Sciences,former president of Tsinghua University,and chair of the Tengchong Scientists Forum.ACADEMICIAN of the Chinese Academy of Sciences,former president of Tsinghua University,and chair of the Tengchong Scientists Forum,Gu Binglin is one of the world’s top physicists and materials scientist,and a pioneer in the field of materials design.
基金supported by National Natural Science Foundation of China(NSFC,22338006,92356301,9235630033 and 22375062)Shanghai Municipal Science and Technology Major Project(21JC1401700)+4 种基金Shanghai Pilot Program for Basic Research(22TQ1400100-10)Fundamental Research Funds for the Central UniversitiesShanghai Pujiang Program(22PJ1402400)“Chenguang Program”supported by Shanghai Education Development Foundation and Shanghai Municipal Education Commission(22CGA32)the Young Elite Scientists Sponsorship Program by CAST(2023QNRC001).
文摘Organic nanophotocatalysts are promising candidates for solar fuels production,but they still face the challenge of unfavorable geminate recombination due to the limited exciton diffusion lengths.Here,we introduce a binary nanophotocatalyst fabricated by blending two polymers,PS-PEG5(PS)and PBT-PEG5(PBT),with matched absorption and emission spectra,enabling a Forster resonance energy transfer(FRET)process for enhanced photocatalysis.These heterostructure nanophotocatalysts are processed using a facile and scalable flash nanoprecipitation(FNP)technique with precious kinetic control over binary nanoparticle formation.The resulting nanoparticles exhibit an exceptional photocatalytic hydrogen evolution rate up to 65 mmol g^(-1) h^(-1),2.5 times higher than that single component nanoparticles.Characterizations through fluorescence spectra and transient absorption spectra confirm the hetero-energy transfer within the binary nanoparticles,which prolongs the excited-state lifetime and extends the namely“effective exciton diffusion length”.Our finding opens new avenues for designing efficient organic photocatalysts by improving exciton migration.
文摘Background: Chronic low back pain is a leading cause of morbidity and disability globally. Low and Middle-Income Countries (LMICs) tend to be more affected, with chronic low back pain (CLBP) being among the leading presenting complaints at specialist consultation. The exact burden of this disease is sparingly known in our setting. Objective: To evaluate the burden of chronic low back pain at the Yaounde Central Hospital. Methods: This was a descriptive cross-sectional study for a period of 3 months, from March 2022 to May 2022. After obtaining ethical clearance and research authorisations, data was collected using structured questionnaires from patients with chronic low back pain presenting at the Yaounde Central Hospital during the aforementioned time frame. This data was then tabulated with the Statistical Package for Social Sciences (SPSS 23.0), and disability was assessed using the modified Roland Morris Disability Questionnaire and the Oswestry Disability Index. Data analysis was done using the International Business Machines Statistical Package for Social Sciences (IBM-SPSS) VERSION 23.0. Results: 115 cases of CLBP were included. The mean age was 52.62 years, and the sex ratio was 0.3. The average monthly income was less than 50,000 frs CFA, in 37.4% of cases. In 57.9%, patients had a job that involved physical labour. The patients had a secondary level of education in 40.9%, and alcohol consumption was observed in 36%. The average number of days of a work stoppage due to LBP was 12.75 days (±12SD), and the median duration of CLBP was 7.15 (7.5SD) years. The median pain intensity was 7 (±2SD), with leg pain and sensory neuropathy observed in 67.8% and 63.5% respectively. Lumbar X-ray was done in 45.2% and revealed lumbar osteoarthrosis in 62.4%. Hypertension as a comorbidity was observed in 26.1%. Medical treatment was used at least once in 98.3% of cases. The average cost of management per month was assessed, and the median was 52,000 FCFA (±20,876 SD). Using the Oswestry Disability Questionnaire, 46 patients, that is 40% of the study population, were classified as severely disabled with a median ODI score of 40%. The factors which were independently associated with disability were level of education, alcohol consumption, treatment modality, pain intensity, body mass index (BMI), psychological wellbeing and number of sick leave days. Conclusion: Chronic low back pain is common in our setting. There is a female predominance with the mean age of the study population situated in the 5th decade. Low-income earners and patients with a job involving physical labour were the most affected. Medical treatment was the main therapeutic modality, with the average cost of management per month being above the average monthly income of the greater majority of the patients. Several factors influenced disability, some of which were independently associated with it, such as level of education, alcohol consumption and treatment modality.
文摘The International Health Regulations(IHR)of the republic of South Africa confirmed 20 human monkeypox(mpox)cases including the death of 3 individuals to the World Health Organization(WHO)between 8 May and 2 July 2024.All the cases were men aged between 17 and 43 years and 11 were men who have sex with men.Out of these cases,15 cases were living with un-managed or recently diagnosed HIV infection.All these cases were symptomatic with extensive skin lesions and required hospitalization.This sudden incidence of mpox cases without any prior history of international travel,high prevalence of HIV and high case fatality ratio,suggests that the community transmission is still prevalent.Rise of mpox cases in vulnerable groups in South Africa has the potential for increased health impact in people living in neighboring countries and has the risk of cross border and international spread.Due to this reason,national health authorities in South Africa have initiated various response measures with the support from the WHO to control this infection[1].
基金supported by National Natural Science Foundation of China(Nos.32121005,22225805,22308101,and 32394001)Shanghai Science and Technology Innovation Action Plan(No.23J21901600)+2 种基金Innovation Program of Shanghai Municipal Education Commission,Shanghai Frontier Science Research Base of Optogenetic Techniques for Cell Metabolism(Shanghai Municipal Education Commission,No.2021 Sci&Tech 03-28)the China Postdoctoral Science Foundation(No.2021M701199)Natural Science Foundation of Shanghai(No.23ZR1416600).
文摘Singlet oxygen(^(1)O_(2)),as the primary reactive oxygen species in photodynamic therapy,can effectively induce excessive oxidative stress to ablate tumors and kill germs in clinical treatment.However,monitoring endogenous^(1)O_(2)is greatly challenging due to its extremely short lifetime and high reactivity in biological condition.Herein,we report an ultra-high signal-to-ratio near-infrared chemiluminescent probe(DCMCy)for the precise detection of endogenous^(1)O_(2)during photodynamic therapy(PDT).The methoxy moiety was removed from enolether unit in DCM-Cy to suppress the potential self-photooxidation reaction,thus greatly eliminating the photoinduced background signals during PDT.Additionally,the compact cyclobutane modification of DCM-Cy resulted in a significant 6-fold increase in cell permeability compared to conventional adamantane-dioxane probes.Therefore,our“step-by-step”strategy for DCM-Cy addressed the limitations of traditional chemiluminescent(CL)probes for^(1)O_(2),enabling effectively tracking of endogenous^(1)O_(2)level changes in living cells,pathogenic bacteria and mice in PDT.
基金support from the National Natural Science Foundation of China(9235630033,22105069)Shanghai Pujiang Program(20PJ1402900)+2 种基金Shanghai Natural Science Foundation(21ZR1418400)Innovation Program of Shanghai Municipal Education Commission(2023FGS01)Natural Science Foundation of Jiangsu Province(BK20231225).
文摘Icing detection is critically important for preventing safety accidents and economic losses,especially concerning ice formation from invalidated anti-icing fluids(water and ethylene glycol)under extreme conditions.Traditional technologies like ultrasonics and capacitor-antenna face challenges with limited detection areas,lower accuracy,and susceptibility to electromagnetic interference.Here,we introduce a novel viscosity-ultrasensitive fluorescent probe 40,4‴-(2,2-diphenyle-thene-1,1-diyl)bis-(3,5-dicarboxylate)(TPE-2B4C)based on AIEgens for moni-toring ice formation of anti-icing fluids in low-temperature environments.TPE-2B4C,consisting of four sodium carboxylate groups and multiple freely rotating benzene rings,demonstrates outstanding solubility in anti-icing fluids and exhibits no fluorescent background signal even at low temperatures(<−20°C).Upon freezing,TPE-2B4C relocates from the water phase to higher viscosity ethylene glycol,causing restriction of benzene rings and a significantly increased green fluorescence signal.TPE-2B4C can successfully determine whether the anti-icing fluids are icing from−5 to−20°C with a high contrast ratio.Due to its simple setup,fast operation,and broad applicability,our new method is anticipated to be employed for rapid,real-time,and large-scale icing detection.
基金supported financially by National Natural Science Foundation of China(NSFC)(Nos.22478115,22075083)the Programme of Introducing Talents of Discipline to Universities(No.B16017).
文摘The development of high-performance,reproducible carbon(C)-based supercapacitors remains a significant challenge because of limited specific capacitance.Herein,we present a novel strategy for fabricating LaCoO_(x) and cobalt(Co)-doped nanoporous C(LaCoO_(x)/Co@ZNC)through the carbonization of Co/Zn-zeolitic imidazolate framework(ZIF)crystals derived from a PVP-Co/Zn/La precursor.The unique ZIF structure effectively disrupted the graphitic C framework,preserved the Co active sites,and enhanced the electrical conductivity.The synergistic interaction between pyridinic nitrogen and Co ions further promoted redox reactions.In addition,the formation of a hierarchical pore structure through zinc sublimation facili-tated electrolyte diffusion.The resulting LaCoO_(x)/Co@ZNC exhibited exceptional electrochemical performance,delivering a remarkable specific capacitance of 2,789 F/g at 1 A/g and outstanding cycling stability with 92%capacitance retention after 3,750 cycles.Our findings provide the basis for a promising approach to advancing C-based energy storage technologies.
文摘A combination of hard(SiCP)and soft(fly ash)particulate reinforcements could be a strategy to enhance combination of multiple properties of Magnesium and its alloys which otherwise suffer from low stiffness,low wear resistance,and many other critical properties.However,at present a comprehensive and robust map correlating different properties in particle-reinforced composites is much lacking.In this work,an industrial grade AZ91 magnesium alloy reinforced with hard SiC and soft fly ash particles(with 3 vol.%each),has been prepared using stir casting followed by hot extrusion at 325℃with a ratio of 21.5.Microstructure of the hybrid composite was characterized using optical and scanning electron microscopes.The composite exhibited a reduction in average grain size from 13.6 to 7.1μm,concomitantly an increase in Vickers hardness from 73 to 111 HV.The tension-compression yield asymmetry ratios of the unreinforced alloy and hybrid composite were 1.165 and 0.976,respectively indicating higher yield strength for the composite under compressive load.The composite exhibited 76%improvement in damping capacity under time sweep mode,and 28%improvement at 423 K under temperature sweep mode.The tribological characteristics of the composite under dry sliding conditions at sliding speeds and loads in the range of 0.5 to 1.5 m s^(-1)and 10 to 30 N,respectively showed higher wear resistance than the unreinforced alloy.The composite showed 23%improvement in sliding wear resistance at a load of 20 N and a speed of 1 m s^(-1).Finally,efforts have been made to understand the influence of one property on the other by developing statistical property correlation maps from the properties obtained in this study and from the literature.These maps are expected to help in the design of hybrid Metal Matrix Composites for a variety of targeted applications in different sectors.
基金supported by National Natural Science Foundation of China(Nos.22325602,22176060)Program of Shanghai Academic/Technology Research Leader(No.23XD1421000)+2 种基金Project supported by Shanghai Municipal Science and Technology Major Project(No.2018SHZDZX03)the Program of Introducing Talents of Discipline to Universities(No.B16017)Science and Technology Commission of Shanghai Municipality(No.20DZ2250400)。
文摘H_(2)O_(2)is an environmentally friendly oxidizing agent with minimal secondary pollution;however,its application has always been constrained by factors such as storage and transportation.In this study,we propose an innovative method for storing and releasing H_(2)O_(2)using hydrogels.Commercial hydrogels(sodium polyacrylate)can undergo swelling and absorb H_(2)O_(2)in aqueous solutions,and the swollen hydrogel can continuously release H_(2)O_(2)under osmotic pressure.And the characteristics of osmotic pressure drive ensure the recyclability of hydrogel for H_(2)O_(2)storage.Experimental results demonstrate that H_(2)O_(2)can stably exist within the hydrogel for an extended period,and this strategy helps to avoid explosion the risk and potential environmental hazards during the transportation of H_(2)O_(2).Finally,experiments confirm that the hydrogel controlled sustained release of H_(2)O_(2)is effective in both Fenton reactions and the process of bacterial inactivation.This work introduces new ideas for the storage of H_(2)O_(2),and the sustained release of H_(2)O_(2)may have significant implications in the fields of healthcare,environmental science,catalysis,and beyond.
基金The authors acknowledged Universiti Putra Malaysia for the Putra Grant that was received(GP-IPM 9787700)supported by Grant PN-III-P4-PCE-2021-0993,UEFISCDI,Romania.
文摘Modeling the boundary layer flow of ternary hybrid nanofluids is important for understanding and optimizing their thermal performance,particularly in applications where enhanced heat transfer and fluid dynamics are essential.This study numerically investigates the boundary layer flow of alumina-copper-silver/water nanofluid over a permeable stretching/shrinking sheet,incorporating both first and second-order velocity slip.The mathematical model is solved in MATLAB facilitated by the bvp4c function that employs the finite difference scheme and Lobatto IIIa formula.The solver successfully generates dual solutions for the model,and further analysis is conducted to assess their stability.The findings reported that only one of the solutions is stable.For the shrinking sheet case,increasing the first-order velocity slip delays boundary layer separation and enhances heat transfer,while,when the sheet is stretched,the second-order velocity slip accelerates separation and improves heat transfer.Boundary layer separation is most likely to occur when the sheet is shrinking;however,this can be controlled by adjusting the velocity slip with the inclusion of boundary layer suction.
基金Project supported by the National Key Research and Development Program(2022YFB3504200)National Natrual Science Foundation of China(22376061,21922602,22076047,U21A20326)+1 种基金Shanghai Science and Technology Innovation Action Plan(20dz1204200)Fundamental Re search Funds for the Central Universities。
文摘Pd-based catalysts have been extensively studied in the catalytic oxidation of methane,but their longterm stability and water resistance are unsatisfactory as the active sites are susceptible to water toxicity.The addition of Pt to Pd-based catalysts is found to be the most effective and promising method.However,distinct states of existence of Pt can affect the catalytic performance to different degrees,even negatively.Therefore,the impact mechanism of Pt on Pd-based catalysts needs to be further understood.In this work,A-site defective La_(0.9)AlO_(x)perovskite was used as a support,and the state of Pt in catalysts was regulated by adjusting the introducing sequence of Pd and Pt,It is found that only when Pt is introduced preferentially,the activity and water resistance of the bimetal can be improved.Combining a series of characterization results of the fresh catalysts,reduced catalysts,and the samples after reduction and use,it is found that the higher Pt^(2+)content in the catalyst is the main reason for promoting bimetallic properties,while more Pt0has an inhibitory effect.This work provides a new understanding of the promotion effect of Pt on Pd-Pt bimetal in the catalytic oxidation reaction of methane.
基金supported by the National Key Research and Development Program of China(2021YFA0910000)NSFC Excellent Young Scientist Scheme(22222803)+1 种基金the NSFC Science Center Program(21788102),NSFC(22408105)the China Postdoctoral Science Foundation(2022M72142).
文摘The development of efficient aggregation-induced emission(AIE)active probes is crucial for disease diagnosis,particularly for tumors and cardiovascular diseases.Current AIE-active probes primarily focus on improving their water solubility to resist aggregation,thereby achieving an initial fluorescence-off state.However,the complex biological environment can cause undesirable aggregation,resulting in false signals.To address this issue,we have ingeniously introduced an azo group into the AIE luminogen(AIEgen),developing a reductase-activated AIE probe,Azo-quinoline-malononitrile(QM)-PN,for imaging hypoxic environments.In this probe,the azo group promotes intramolecular motion through rapid E/Z isomerization,causing the excited state energy to dissipate via non-radiative decay,thus turning off the initial fluorescence.In the presence of reductase,Azo-QM-PN is reduced and cleaved to produce the hydrophobic AIEgen NH_(2)-QM-PN,which subsequently aggregates and generates an in situ AIE signal,thereby imaging the hypoxic environment with reductase.Encapsulation of Azo-QM-PN with DSPEPEG2000 results in the formation of the nanoprobe Azo-QM-PN NPs,which can effectively penetrate cell membranes,specifically illuminate tumor cells,monitor fluctuations in azo reductase levels,and deeply penetrate and image multicellular tumor spheroids,demonstrating potential for hypoxic tumor imaging.Additionally,the nanoprobe Azo-QM-PN NPs can selectively image hypoxic atherosclerotic plaque tissues,showing potential for detecting atherosclerosis.Therefore,in this study,we successfully developed an enzyme-activated AIE probe for imaging hypoxic environments,laying the foundation for further clinical applications.
