Pectin is a natural polysaccharide with a complex structure consisting of linear and branched regions rich in galacturonic acid.The growing interest in orange peel pectin can be attributed to its abundant supply.Accor...Pectin is a natural polysaccharide with a complex structure consisting of linear and branched regions rich in galacturonic acid.The growing interest in orange peel pectin can be attributed to its abundant supply.According to statistics,about 10 million tons of orange peel waste are produced worldwide each year.Traditionally,the extraction and utilization of pectin have focused on its gelling,thickening,and stabilizing properties in food.However,as more and more research teams have found that pectin has good biocompatibility,biodegradability and easy chemical modification,its potential in drug delivery systems,tissue engineering,and wound healing is gradually being explored.This review focuses on orange peel pectin polysaccharides and discusses its traditional and modern extraction techniques,especially the advanced method of subcritical water extraction.This study also outlines the structural modifications of pectin such as methylation and acetylation,and introduces its antioxidant and anticancer biological activities and their emerging roles in the development of advanced biomaterials such as bone tissue engineering and fibre pad dressings.展开更多
Structural modification of three dimensional(3D)materials for the application of dielectric loss-based microwave absorbing materials(MAMs)usually relies on intricate synthesis process and can pose challenges in terms ...Structural modification of three dimensional(3D)materials for the application of dielectric loss-based microwave absorbing materials(MAMs)usually relies on intricate synthesis process and can pose challenges in terms of scalability and mass production for practical application.In this work,we reported a successful attempt in modifying the 3D structure of mesoporous lanthanum oxide(La_(2)O_(3))for effective broadband MAMs candidate via simple co-precipitation process.The inclusion of cetyltrimethylammonium bromide(CTAB)and hydrothermal aging treatment result in a significant transformation of La_(2)O_(3)particles from their original polygonal form to a 3D coral-like and nano needle-like structure.The utilization of CTAB and hydrothermal aging results in the increase of surface area and a two-fold increase in pore volume of the resulting La_(2)O_(3).Due to its unique 3D structure,the 3D coral-like and nano needle-like La_(2)O_(3)materials possess a broadband electromagnetic(EM)wave absorption characteristic with the effective absorption bandwidth(EAB)covering the C-band frequency range.Specifically,in the La_(2)O_(3)C-H sample(with CTAB-with hydrothermal),it exhibits strong EM wave absorption with a reflection loss(RL)value of-33.07 dB which equals to 99.95%EM wave absorption at a thickness of only 1.50 mm.The detailed analysis of EM wave absorption properties reveals that the improvement of La_(2)O_(3)materials to attenuate EM wave energy arises from the dielectric loss phenomenon,the enhanced interfacial polarization,multiple reflections mechanism,and conduction loss mechanism induced by the 3D structural formation of the La_(2)O_(3)structure.This work proposes a novel and efficient approach in synthesizing and modifying 3D materials for effective broadband EM wave absorption.展开更多
Parthenolide(PTL)is a sesquiterpene lactone derived from medicinal plant feverfew(Tanacetum parthenium).Recent studies have demonstrated that it has multiple pharmacological activities,especially in the treatment of v...Parthenolide(PTL)is a sesquiterpene lactone derived from medicinal plant feverfew(Tanacetum parthenium).Recent studies have demonstrated that it has multiple pharmacological activities,especially in the treatment of various hematological and solid cancers.The superior anticancer activity of PTL suggests that it has the potential to be a first-line drug.However,due to the limited physical and chemical properties,as well as bioavailability,structural modification strategies are strongly recommended to improve the anticancer activity.This review describes representative PTL derivatives obtained by different modification strategies,which are reported to exert antiproliferative activities superior to the parent compound PTL.Furthermore,we also summarize their basic mechanisms on cancer-related signaling pathways,so as to explain the potential and characteristics of PTL and its derivatives in cancer therapy.展开更多
Recent development in the modification of ceria-based catalysts for exhaust gas treatment was reviewed with the dependence of redox properties on structural characters of materials. The doping of ceria with different ...Recent development in the modification of ceria-based catalysts for exhaust gas treatment was reviewed with the dependence of redox properties on structural characters of materials. The doping of ceria with different cations such as rare earth or transition metal oxides results in improvement of structural stability, catalytic function and resistance to sintering at high temperatures. Aging and reduction treatment at high temperatures promote ceria reduction and is beneficial for oxygen storage capacity of the three-way catalysts. Chemical filing technique is very effective in modifying the redox property in the low temperature regions.展开更多
Oleanolic acid(OA),a pentacyclic triterpenoid,exhibits a broad spectrum of biological activities,including antitumor,antiviral,antibacterial,anti-inflammatory,hepatoprotective,hypoglycemic,and hypolipidemic effects.Si...Oleanolic acid(OA),a pentacyclic triterpenoid,exhibits a broad spectrum of biological activities,including antitumor,antiviral,antibacterial,anti-inflammatory,hepatoprotective,hypoglycemic,and hypolipidemic effects.Since its initial isolation and identification,numerous studies have reported on the structural modifications and pharmacological activities of OA and its derivatives.Despite this,there has been a dearth of comprehensive reviews in the past two decades,leading to challenges in subsequent research on OA.Based on the main biological activities of OA,this paper comprehensively summarized the modification strategies and structureactivity relationships(SARs)of OA and its derivatives to provide valuable reference for future investigations into OA.展开更多
Under certain conditions, ultrafast pulsed laser interaction with matter leads to the formation of self-organized conical as well as periodic surface structures （commonly reffered to as, laser induced periodic surfac...Under certain conditions, ultrafast pulsed laser interaction with matter leads to the formation of self-organized conical as well as periodic surface structures （commonly reffered to as, laser induced periodic surface structures, LIPSS）. The purpose of the present investigations is to explore the effect of fsec laser fluence and ambient environments （Vacuum ＆ 02） on the formation of LIPSS and conical structures on the Ti surface. The surface morphology was investigated by scanning electron microscope （SEM）. The ablation threshold with single and multiple （N = 100） shots and the existence of an incubation effect was demonstrated by SEM investigations for both the vacuum and the 02 environment. The phase analysis and chemical composition of the exposed targets were performed by x-ray diffraction （XRD） and energy dispersive x-ray spectroscopy （EDS）, respectively. SEM investigations reveal the formation of LIPSS （nano ＆ micro）. FFT d-spacing calculations illustrate the dependence of periodicity on the fluence and ambient environment. The periodicity of nano-scale LIPSS is higher in the case of irradiation under vacuum conditions as compared to 02. Furthermore, the 02 environment reduces the ablation threshold. XRD data reveal that for the 02 environment, new phases （oxides of Ti） are formed. EDS analysis exhibits that after irradiation under vacuum conditions, the percentage of impurity element （A1） is reduced. The irradiation in the 02 environment results in 15% atomic diffusion of oxygen.展开更多
Natural steroids have been showing notable cytotoxic activities, which are quite interesting lead compounds for the development of anticancer drug including estramustine and prednimustine. Considering that these semi-...Natural steroids have been showing notable cytotoxic activities, which are quite interesting lead compounds for the development of anticancer drug including estramustine and prednimustine. Considering that these semi-synthetic molecules are nitrogen mustard functionalized steroidal derivatives, the present review is focused on the methodologies of introducing nitrogen atom or nitrogen-containing heterocycles on A^D rings or side chains of steroids, and analysis of the structure-activity relationship（SAR） for these man-made cytotoxic steroids.展开更多
Sensitivity analysis and structural modification techniques are used to investigate the structural modifications of a machine gun tripod which suffers from severe vibration during firing due to the resonance. The fini...Sensitivity analysis and structural modification techniques are used to investigate the structural modifications of a machine gun tripod which suffers from severe vibration during firing due to the resonance. The finite element analysis and modal test techniques are used to determine the natural frequencies of the machine gun. The sensitivities of natural frequencies with respect to the structural parameters of the tripod are obtained by the method of sensitivity analysis, and they can be used as an indication for the structural modification of the tripod so as to shift the natural frequencies effectively. By the structural modification techniques, finally, the optimal structural modifications of the tripod for desired natural frequencies are made to avoid the resonance, and this optimal structural modification is verified by re-analysis of the modified structure and the vibration contrast between original structure and modified structure. The research resulted in a successful structural modification for desired natural frequencies, which can avoid the resonance and thereby greatly improve the shooting precision of the machine gun during firing.展开更多
Work-hardening behaviour of type 316 austenitic stainless steel having difFerent initial dislocation structures introduced by swaging to various levels is analysed by a simplified Kock's model which takes into acc...Work-hardening behaviour of type 316 austenitic stainless steel having difFerent initial dislocation structures introduced by swaging to various levels is analysed by a simplified Kock's model which takes into account the structural changes through the dislocation accumulation and annihilation process during deformation. The dislocation accumulation and annihilation factors show a temperature and structure dependence. The dislocation annihilation factor shows a plateau or decreasing tendency in the dynamic strain ageing (DSA) temperature range. This is attributed as either due to dislocation accumulation being more pronounced than dislocation annihilation or as due to precipitates being formed at DSA temperatures acting as obstacles to dislocation motion in the DSA temperature range.展开更多
This paper reviews recent progress in the structural modification and activities on Panax notoginseng saponins(PNS).PNS can not only improve the function of cardio-cerebral system,central nervous system and immune sys...This paper reviews recent progress in the structural modification and activities on Panax notoginseng saponins(PNS).PNS can not only improve the function of cardio-cerebral system,central nervous system and immune system,but also reveal anticancer,anti-aging and anti-oxidation activities.In order to solve the problem of low bioavailability and poor absorbability of PNS in vivo,usually,the researchers modified the structure of PNS with three methods:glycoside cleavage(including acid hydrolysis,sulfation,etc.),biotransformation method(including enzyme hydrolysis,microbial transformation)and combinatorial chemical method.It was found that the structural modification sites of PNS were single,mainly aimed at C-3,C-6 and C-20,which provided a new perspective for the structural modification of PNS.Therefore,structural modification on PNS with high yield and ready availability are significant in the discovery of new active ingredients and industrialization.Derivatives of PNS are applied to research of structure-activity relationship,which is beneficial to the development of new medicines.展开更多
In this study,carboxylated multi-walled carbon nanotubes(CNTs)were utilized to address the challenges of inherent conductivity mismatch of CuCoO_(2)catalysts.CNT-supported CuCoO_(2)nanosheets(CCO/xCNT,x=25,50,and 75)w...In this study,carboxylated multi-walled carbon nanotubes(CNTs)were utilized to address the challenges of inherent conductivity mismatch of CuCoO_(2)catalysts.CNT-supported CuCoO_(2)nanosheets(CCO/xCNT,x=25,50,and 75)were successfully synthesized through a one-step hydrothermal method.The introduction of CNTs can reduce the thickness of CuCoO_(2)to 25 nm due to the interaction between the CNTs and CuCoO_(2),change the electronic structure,and increase the O-Co bond length and oxygen vacancy(V_(O))concentration of CuCoO_(2).These microstructure modifications significantly enhance the binding affinity between CuCoO_(2)and OH^(-).The OER measurements of CCO/xCNT(x=25,50,and 75)electrocatalysts reveal that adding 50 wt%CNTs into the sample(CCO/50CNT)yields the best catalytic performance,which shows a low overpotential of only 343 mV at 10 mA cm^(-2)and a small Tafel slope of 65 mV dec^(-1).Additionally,CCO/50CNT also exhibits excellent structural and compositional stability.The density functional theory(DFT)calculations and pH dependence experiments show that the introduction of CNTs can generate V_(O),which initiates lattice oxygen and facilitates both the Adsorption Evolution Mechanism(AEM)and the Lattice Oxygen Mechanism(LOM)on the catalyst surface during the OER process.A simple and general strategy is used to modify the catalyst microstructure and influence its OER mechanism,which helps to improve the OER performance of delafossite type metal oxides and even bimetallic oxides.展开更多
Natural products(NPs)are invaluable resources for drug discovery,characterized by their intricate scaffolds and diverse bioactivities.Al drug discovery&design(AIDD)has emerged as a transformative approach for the ...Natural products(NPs)are invaluable resources for drug discovery,characterized by their intricate scaffolds and diverse bioactivities.Al drug discovery&design(AIDD)has emerged as a transformative approach for the rational structural modification of NPs.This review examines a variety of molecular generation models since 2020,focusing on their potential applications in two primary scenarios of NPs structure modification:modifications when the target is identified and when it remains unidentified.Most of the molecular generative models discussed herein are open-source,and their applicability across different domains and technical feasibility have been evaluated.This evaluation was accomplished by integrating a limited number of research cases and successful practices observed in the molec-ular optimization of synthetic compounds.Furthermore,the challenges and prospects of employing molecular generation modeling for the structural modification of NPs are discussed.展开更多
The quantum anomalous Hall(QAH)effect in two-dimensional(2D)topological materials has attracted widespread attention due to its potential for dissipationless chiral edge transport without an external magnetic field,wh...The quantum anomalous Hall(QAH)effect in two-dimensional(2D)topological materials has attracted widespread attention due to its potential for dissipationless chiral edge transport without an external magnetic field,which is highly promising for low-power electronic applications.However,identifying materials that exhibit these properties remains particularly challenging,as only a limited number of such materials are known,raising the intriguing question of whether it is possible to induce the QAH effect in materials with ordinary properties through structural modifications.In this work,we grow an unreported 2D titanium selenide(Ti_(3)Se_(4))on a Cu(111)substrate using molecular beam epitaxy.Low-energy electron diffraction and scanning tunneling microscopy characterizations reveal a√7×√7 brick-like structure.First-principles calculations and X-ray photoelectron spectroscopy measurements confirm its composition to be Ti_(3)Se_(4).Our calculations further demonstrate that monolayer Ti_(3)Se_(4),in its grown form on Cu(111),has the potential to host the QAH effect.Interestingly,when we examine its freestanding form,the monolayer transitions from a QAH insulator candidate into a conventional semiconductor,despite only minor differences in their atomic structures.This transition enlightens us that subtle lattice adjustments can induce a transition from semiconductor to QAH properties in freestanding Ti_(3)Se_(4).This discovery provides a potential route to engineering practical materials that may exhibit the QAH effect.展开更多
To date,extensively high demand for hydrogen peroxide(H_(2)O_(2))has been predominantly supplied by the anthraquinone process for several worldwide applications,encompassing wastewater treatment,environmental remediat...To date,extensively high demand for hydrogen peroxide(H_(2)O_(2))has been predominantly supplied by the anthraquinone process for several worldwide applications,encompassing wastewater treatment,environmental remediation,and chemical synthesis.However,the compacted manufacturing,massive energy input and the release of tremendous wastes have restricted commercialization feasibility.Regards to mitigate such issues,the photocatalytic H_(2)O_(2)production by utilizing g-C_(3)N_(4)catalysts has endowed a greener,sustainable and promising alternative,considering that it involves water and oxygen as reactants in the present of sunlight as energy input.Herein,we have manifested a comprehensive overview of the research progress for g-C_(3)N_(4)-based semiconductors for photocatalytic H_(2)O_(2)generation.This review has systematically elucidated state-of-the-art development of different modifications on g-C_(3)N_(4)to unravel the fundamental mechanism of H_(2)O_(2)evolution via oxygen reduction reaction(ORR)and water oxidation reaction(WOR).In addition,the contribution made by vacancy introduction,doping,heterogenization,and co-catalyst passivation with respect to photoefficiency enhancement have been clarified.Furthermore,the current challenges and perspective of future development directions on photocatalytic H_(2)O_(2)production have also been highlighted.As such,g-C_(3)N_(4)stands as the next step toward advancement in the configuration and modulation of high-efficiency photocatalysts.展开更多
Ischemic stroke(IS)presents a major threat to human life and health due to its high disability and mortality rates.3-n-Butylphthalide(NBP),derived from celery seeds of the Apiaceae family native to the Mediterranean r...Ischemic stroke(IS)presents a major threat to human life and health due to its high disability and mortality rates.3-n-Butylphthalide(NBP),derived from celery seeds of the Apiaceae family native to the Mediterranean region,was first introduced in China for acute IS treatment in 2004.NBP demonstrates multiple therapeutic actions,including reconstruction of microcirculation in the cerebral ischemia area,inhibition of platelet aggregation,reduction of cerebral infarction volume,maintenance of blood-brain barrier(BBB)integrity,and enhancement of cerebral blood perfusion.However,its overall efficacy remains moderate,limited by poor water solubility and low bioavailability,which constrains its clinical application.To address these limitations,researchers have actively pursued the development of NBP derivatives and analogs,achieving notable progress.These efforts,including substituent introduction,ring opening derivatization,esterification,and atom substitution,have generated diverse NBP derivatives.Several of these derivatives have advanced to clinical studies.Specifically,potassium 2-(1-hydroxypentyl)-benzoate(PHPB),brozopentyl sodium(BZP),and XY-03-EA(ZONK1103)have reached phase II clinical trials,while(S)-2-(1-acetoxypentyl)benzoic acid L-arginine salt(AAPB)has received clinical trial approval for 2024.This review examines the structural modification and optimization of NBP over the past two decades from a medicinal chemistry perspective,aiming to facilitate the development of superior derivatives and advance cerebral ischemia treatment.展开更多
High-temperature proton exchange membranes(HT-PEMs) possess excellent thermal and outstanding electrochemical stability, providing an avenue to realize high-temperature proton exchange membranes fuel cells(HT-PEMFCs) ...High-temperature proton exchange membranes(HT-PEMs) possess excellent thermal and outstanding electrochemical stability, providing an avenue to realize high-temperature proton exchange membranes fuel cells(HT-PEMFCs) with both superior power density and long-term durability. Unfortunately, polybenzimidazole(PBI), a typical material for conventional HT-PEMs, fails to compromise the high nonaqueous proton conductivity and high mechanical properties, thus hindering their practical applications.Achieving efficient nonaqueous proton conduction is crucial for HT-PEMFC, and many insightful research works have been done in this area. However, there still lacks a report that integrates the host-vip interactions of phosphoric acid doping and the structural stability of polymers to systematically illustrate modification strategies. Here, we summarize recent advancements in enhancing the nonaqueous proton conduction of HT-PEMs. Various polymer structure modification strategies, including main chain and side group modification, cross-linking, blocking, and branching, are reviewed. Composite approaches of polymer, including compounding with organic porous polymers, filling the inorganic components and modifying with ionic liquids, etc., are also covered in this work. These strategies endow the HT-PEMs with more free volume, nanophase-separated structure, and multi-stage proton transfer channels, which can facilitate the proton transportation and improve their performance. Finally, current challenges and future directions for further enhancements are also outlined.展开更多
Aim To afford an environmentally benign catalytic epoxidation of carbon-carbon double bonds in organic substrates using hydrogen peroxide as an oxidant and iodine as a catalyst.Method The effects of different factors ...Aim To afford an environmentally benign catalytic epoxidation of carbon-carbon double bonds in organic substrates using hydrogen peroxide as an oxidant and iodine as a catalyst.Method The effects of different factors on the epoxidation of three unsaturated natural products were investigated by orthogonal design.Results The experimental results show that three unsaturated natural products are oxidized to the corresponding epoxides with hydrogen peroxide in the presence of 10%(mol/mol) of iodine at room temperature in high yields.Conclusion Iodine was found to be an efficient catalyst for the epoxidation of carbon-carbon double bonds in some unsaturated natural products with hydrogen peroxide at room temperature.展开更多
Regulation of optical properties and electronic structure of graphitic carbon nitride （g-C3N4 ） via external strain has attracted much attention due to its potential in photocatalyst and electronic devices. However,...Regulation of optical properties and electronic structure of graphitic carbon nitride （g-C3N4 ） via external strain has attracted much attention due to its potential in photocatalyst and electronic devices. However, the identifi- cation of g-C3N4 structure transformation induced by strain is greatly lacking. In this work, the Raman spectra of g-C3N4 with external strain are determined theoretically based on the density function theory. Deformation induced by external strain not only regulates the Raman mode positions but also leads to a I^aman mode split- ting, which can be ascribed to crystal symmetry destruction by strain engineering. Our results suggest the use of Raman scattering in structural identification in deformed 9-C3N4 structure.展开更多
Objective To study mechanism of various effects of HLA antigen camouflaged by differentmPEGs. Methods Effects of the modification of HLA antigen camouflaged by various mPEGs were detected by microlymphocytotoxicity te...Objective To study mechanism of various effects of HLA antigen camouflaged by differentmPEGs. Methods Effects of the modification of HLA antigen camouflaged by various mPEGs were detected by microlymphocytotoxicity test. The ability of modification was detected by SDS-PAGE. The mechanism of the modification was depicted by the three-dimensional structure of HLA antigen. Results The specific reaction between HLA-A2 antigen and its antibody were completely blocked by mPEG-BTC and mPEG-SPA. mPEG-MAL did not camouflage HLA antigen. The diversity of the modification of HLA antigen camouflaged by varied mPEGs was closely associated with the amides displayed on the surface of HLA antigen. Conclusion Only the amides which were exposed to the surface of HLA antigen can be camouflaged by mPEG. The amides on the surface of three-dimensional structure of HLA-A2 antigen determine the effect of the modification by various mPEGs.展开更多
文摘Pectin is a natural polysaccharide with a complex structure consisting of linear and branched regions rich in galacturonic acid.The growing interest in orange peel pectin can be attributed to its abundant supply.According to statistics,about 10 million tons of orange peel waste are produced worldwide each year.Traditionally,the extraction and utilization of pectin have focused on its gelling,thickening,and stabilizing properties in food.However,as more and more research teams have found that pectin has good biocompatibility,biodegradability and easy chemical modification,its potential in drug delivery systems,tissue engineering,and wound healing is gradually being explored.This review focuses on orange peel pectin polysaccharides and discusses its traditional and modern extraction techniques,especially the advanced method of subcritical water extraction.This study also outlines the structural modifications of pectin such as methylation and acetylation,and introduces its antioxidant and anticancer biological activities and their emerging roles in the development of advanced biomaterials such as bone tissue engineering and fibre pad dressings.
基金Project supported by National Research and Innovation Agency through Rumah Program Organisasi Riset Nanoteknologi dan Material Maj u(ORNM)2024Indonesia Ministry of Finance through the competitive research program of RISPRO Kompetisi(PRJ-68/LPDP/2023)。
文摘Structural modification of three dimensional(3D)materials for the application of dielectric loss-based microwave absorbing materials(MAMs)usually relies on intricate synthesis process and can pose challenges in terms of scalability and mass production for practical application.In this work,we reported a successful attempt in modifying the 3D structure of mesoporous lanthanum oxide(La_(2)O_(3))for effective broadband MAMs candidate via simple co-precipitation process.The inclusion of cetyltrimethylammonium bromide(CTAB)and hydrothermal aging treatment result in a significant transformation of La_(2)O_(3)particles from their original polygonal form to a 3D coral-like and nano needle-like structure.The utilization of CTAB and hydrothermal aging results in the increase of surface area and a two-fold increase in pore volume of the resulting La_(2)O_(3).Due to its unique 3D structure,the 3D coral-like and nano needle-like La_(2)O_(3)materials possess a broadband electromagnetic(EM)wave absorption characteristic with the effective absorption bandwidth(EAB)covering the C-band frequency range.Specifically,in the La_(2)O_(3)C-H sample(with CTAB-with hydrothermal),it exhibits strong EM wave absorption with a reflection loss(RL)value of-33.07 dB which equals to 99.95%EM wave absorption at a thickness of only 1.50 mm.The detailed analysis of EM wave absorption properties reveals that the improvement of La_(2)O_(3)materials to attenuate EM wave energy arises from the dielectric loss phenomenon,the enhanced interfacial polarization,multiple reflections mechanism,and conduction loss mechanism induced by the 3D structural formation of the La_(2)O_(3)structure.This work proposes a novel and efficient approach in synthesizing and modifying 3D materials for effective broadband EM wave absorption.
基金supported by the Natural Science Foundation of Jiangsu Province(No.BK20201332)the“Double First-Class”University Project(No.CPU2018GF03)+1 种基金the Six Talent Peaks Project of Jiangsu Province(No.SWYY-107)Jiangsu Province‘333’Project,111 Center from Ministry of Education of China and the State Administration of Foreign Experts Affairs of China(No.B18056).
文摘Parthenolide(PTL)is a sesquiterpene lactone derived from medicinal plant feverfew(Tanacetum parthenium).Recent studies have demonstrated that it has multiple pharmacological activities,especially in the treatment of various hematological and solid cancers.The superior anticancer activity of PTL suggests that it has the potential to be a first-line drug.However,due to the limited physical and chemical properties,as well as bioavailability,structural modification strategies are strongly recommended to improve the anticancer activity.This review describes representative PTL derivatives obtained by different modification strategies,which are reported to exert antiproliferative activities superior to the parent compound PTL.Furthermore,we also summarize their basic mechanisms on cancer-related signaling pathways,so as to explain the potential and characteristics of PTL and its derivatives in cancer therapy.
文摘Recent development in the modification of ceria-based catalysts for exhaust gas treatment was reviewed with the dependence of redox properties on structural characters of materials. The doping of ceria with different cations such as rare earth or transition metal oxides results in improvement of structural stability, catalytic function and resistance to sintering at high temperatures. Aging and reduction treatment at high temperatures promote ceria reduction and is beneficial for oxygen storage capacity of the three-way catalysts. Chemical filing technique is very effective in modifying the redox property in the low temperature regions.
基金supported by the Lianyungang Postdoctoral Research Funding Program(No.LYG20210018).
文摘Oleanolic acid(OA),a pentacyclic triterpenoid,exhibits a broad spectrum of biological activities,including antitumor,antiviral,antibacterial,anti-inflammatory,hepatoprotective,hypoglycemic,and hypolipidemic effects.Since its initial isolation and identification,numerous studies have reported on the structural modifications and pharmacological activities of OA and its derivatives.Despite this,there has been a dearth of comprehensive reviews in the past two decades,leading to challenges in subsequent research on OA.Based on the main biological activities of OA,this paper comprehensively summarized the modification strategies and structureactivity relationships(SARs)of OA and its derivatives to provide valuable reference for future investigations into OA.
文摘Under certain conditions, ultrafast pulsed laser interaction with matter leads to the formation of self-organized conical as well as periodic surface structures （commonly reffered to as, laser induced periodic surface structures, LIPSS）. The purpose of the present investigations is to explore the effect of fsec laser fluence and ambient environments （Vacuum ＆ 02） on the formation of LIPSS and conical structures on the Ti surface. The surface morphology was investigated by scanning electron microscope （SEM）. The ablation threshold with single and multiple （N = 100） shots and the existence of an incubation effect was demonstrated by SEM investigations for both the vacuum and the 02 environment. The phase analysis and chemical composition of the exposed targets were performed by x-ray diffraction （XRD） and energy dispersive x-ray spectroscopy （EDS）, respectively. SEM investigations reveal the formation of LIPSS （nano ＆ micro）. FFT d-spacing calculations illustrate the dependence of periodicity on the fluence and ambient environment. The periodicity of nano-scale LIPSS is higher in the case of irradiation under vacuum conditions as compared to 02. Furthermore, the 02 environment reduces the ablation threshold. XRD data reveal that for the 02 environment, new phases （oxides of Ti） are formed. EDS analysis exhibits that after irradiation under vacuum conditions, the percentage of impurity element （A1） is reduced. The irradiation in the 02 environment results in 15% atomic diffusion of oxygen.
基金Financial support from the National Natural Science Foundation of China(No.21272136)Youth Talent Development Foundation of China Three Gorges University
文摘Natural steroids have been showing notable cytotoxic activities, which are quite interesting lead compounds for the development of anticancer drug including estramustine and prednimustine. Considering that these semi-synthetic molecules are nitrogen mustard functionalized steroidal derivatives, the present review is focused on the methodologies of introducing nitrogen atom or nitrogen-containing heterocycles on A^D rings or side chains of steroids, and analysis of the structure-activity relationship（SAR） for these man-made cytotoxic steroids.
文摘Sensitivity analysis and structural modification techniques are used to investigate the structural modifications of a machine gun tripod which suffers from severe vibration during firing due to the resonance. The finite element analysis and modal test techniques are used to determine the natural frequencies of the machine gun. The sensitivities of natural frequencies with respect to the structural parameters of the tripod are obtained by the method of sensitivity analysis, and they can be used as an indication for the structural modification of the tripod so as to shift the natural frequencies effectively. By the structural modification techniques, finally, the optimal structural modifications of the tripod for desired natural frequencies are made to avoid the resonance, and this optimal structural modification is verified by re-analysis of the modified structure and the vibration contrast between original structure and modified structure. The research resulted in a successful structural modification for desired natural frequencies, which can avoid the resonance and thereby greatly improve the shooting precision of the machine gun during firing.
文摘Work-hardening behaviour of type 316 austenitic stainless steel having difFerent initial dislocation structures introduced by swaging to various levels is analysed by a simplified Kock's model which takes into account the structural changes through the dislocation accumulation and annihilation process during deformation. The dislocation accumulation and annihilation factors show a temperature and structure dependence. The dislocation annihilation factor shows a plateau or decreasing tendency in the dynamic strain ageing (DSA) temperature range. This is attributed as either due to dislocation accumulation being more pronounced than dislocation annihilation or as due to precipitates being formed at DSA temperatures acting as obstacles to dislocation motion in the DSA temperature range.
基金Supported by High-level Talent Training Program for Graduate Students of Tibet University(2020-GSP-B014)National Natural Science Foundation of China(81560589)Yunnan Provincial Department of Science and Technology-Kunming Medical University Applied Basic Research Joint Special Fund(2017FE468-001)。
文摘This paper reviews recent progress in the structural modification and activities on Panax notoginseng saponins(PNS).PNS can not only improve the function of cardio-cerebral system,central nervous system and immune system,but also reveal anticancer,anti-aging and anti-oxidation activities.In order to solve the problem of low bioavailability and poor absorbability of PNS in vivo,usually,the researchers modified the structure of PNS with three methods:glycoside cleavage(including acid hydrolysis,sulfation,etc.),biotransformation method(including enzyme hydrolysis,microbial transformation)and combinatorial chemical method.It was found that the structural modification sites of PNS were single,mainly aimed at C-3,C-6 and C-20,which provided a new perspective for the structural modification of PNS.Therefore,structural modification on PNS with high yield and ready availability are significant in the discovery of new active ingredients and industrialization.Derivatives of PNS are applied to research of structure-activity relationship,which is beneficial to the development of new medicines.
基金Natural Science Foundation of Hubei Province(Grant No.2023AFB085)the Fundamental Research Funds for the Central Universities(WUT:2024III012JL)the National Innovation and Entrepreneurship Training Program for College Students in Wuhan University of Technology(Grant No.S202310497028)for the financial support.
文摘In this study,carboxylated multi-walled carbon nanotubes(CNTs)were utilized to address the challenges of inherent conductivity mismatch of CuCoO_(2)catalysts.CNT-supported CuCoO_(2)nanosheets(CCO/xCNT,x=25,50,and 75)were successfully synthesized through a one-step hydrothermal method.The introduction of CNTs can reduce the thickness of CuCoO_(2)to 25 nm due to the interaction between the CNTs and CuCoO_(2),change the electronic structure,and increase the O-Co bond length and oxygen vacancy(V_(O))concentration of CuCoO_(2).These microstructure modifications significantly enhance the binding affinity between CuCoO_(2)and OH^(-).The OER measurements of CCO/xCNT(x=25,50,and 75)electrocatalysts reveal that adding 50 wt%CNTs into the sample(CCO/50CNT)yields the best catalytic performance,which shows a low overpotential of only 343 mV at 10 mA cm^(-2)and a small Tafel slope of 65 mV dec^(-1).Additionally,CCO/50CNT also exhibits excellent structural and compositional stability.The density functional theory(DFT)calculations and pH dependence experiments show that the introduction of CNTs can generate V_(O),which initiates lattice oxygen and facilitates both the Adsorption Evolution Mechanism(AEM)and the Lattice Oxygen Mechanism(LOM)on the catalyst surface during the OER process.A simple and general strategy is used to modify the catalyst microstructure and influence its OER mechanism,which helps to improve the OER performance of delafossite type metal oxides and even bimetallic oxides.
基金financially supported by the National Science Fund for Distinguished Young Scholars(82325047)Regional Innovation and Development Joint Fund of NSFC(U24A20807)+4 种基金Youth Innovation Promotion Association CAS(2023411)National Natural Science Foundation of China(22477123)Major Projects for Fundamental Research of Yunnan Province(202201BC070002)CAS“Light of West China”Program and CAS Interdisciplinary Innovation Team(xbzg-zdsys-202303)Yunnan Revitalization Talent Support Program:Yunling Scholar Project,Yunnan Province Science and Technology Department(202305AH340005).
文摘Natural products(NPs)are invaluable resources for drug discovery,characterized by their intricate scaffolds and diverse bioactivities.Al drug discovery&design(AIDD)has emerged as a transformative approach for the rational structural modification of NPs.This review examines a variety of molecular generation models since 2020,focusing on their potential applications in two primary scenarios of NPs structure modification:modifications when the target is identified and when it remains unidentified.Most of the molecular generative models discussed herein are open-source,and their applicability across different domains and technical feasibility have been evaluated.This evaluation was accomplished by integrating a limited number of research cases and successful practices observed in the molec-ular optimization of synthetic compounds.Furthermore,the challenges and prospects of employing molecular generation modeling for the structural modification of NPs are discussed.
基金financial support from the National Key R&D Program of China(Nos.2019YFA0308500 and 2018YFA0305800)the National Natural Science Foundation of China(Nos.61925111,61888102,11974422,and U23A6015)+3 种基金CAS Project for Young Scientists in Basic Research(No.YSBR-003)the Strategic Priority Research Program of Chinese Academy of Sciences(Nos.XDB28000000 and XDB30000000)the Fundamental Research Funds for the Central Universities provided to University of Chinese Academy of Sciences and to Renmin University of China(No.22XNKJ30(W.J.))the CAS Key Laboratory of Vacuum Physics.
文摘The quantum anomalous Hall(QAH)effect in two-dimensional(2D)topological materials has attracted widespread attention due to its potential for dissipationless chiral edge transport without an external magnetic field,which is highly promising for low-power electronic applications.However,identifying materials that exhibit these properties remains particularly challenging,as only a limited number of such materials are known,raising the intriguing question of whether it is possible to induce the QAH effect in materials with ordinary properties through structural modifications.In this work,we grow an unreported 2D titanium selenide(Ti_(3)Se_(4))on a Cu(111)substrate using molecular beam epitaxy.Low-energy electron diffraction and scanning tunneling microscopy characterizations reveal a√7×√7 brick-like structure.First-principles calculations and X-ray photoelectron spectroscopy measurements confirm its composition to be Ti_(3)Se_(4).Our calculations further demonstrate that monolayer Ti_(3)Se_(4),in its grown form on Cu(111),has the potential to host the QAH effect.Interestingly,when we examine its freestanding form,the monolayer transitions from a QAH insulator candidate into a conventional semiconductor,despite only minor differences in their atomic structures.This transition enlightens us that subtle lattice adjustments can induce a transition from semiconductor to QAH properties in freestanding Ti_(3)Se_(4).This discovery provides a potential route to engineering practical materials that may exhibit the QAH effect.
基金the Ministry of Higher Education(MOHE)Malaysia under the Fundamental Research Grant Scheme(FRGS)(Ref no:FRGS/1/2020/TK0/XMU/02/1)the Ministry of Science,Technology and Innovation(MOSTI)Malaysia under the Strategic Research Fund(SRF-APP)(S.22015)+4 种基金the National Natural Science Foundation of China(Ref no:22202168)Guangdong Basic and Applied Basic Research Foundation(Ref no:2021A1515111019)Xiamen University Malaysia Investigatorship Grant(Grant no:IENG/0038)Xiamen University Malaysia Research Fund(ICOE/0001,XMUMRF/2021-C8/IENG/0041 and XMUMRF/2019-C3/IENG/0013)Hengyuan International Sdn.Bhd.(Grant no:EENG/0003).
文摘To date,extensively high demand for hydrogen peroxide(H_(2)O_(2))has been predominantly supplied by the anthraquinone process for several worldwide applications,encompassing wastewater treatment,environmental remediation,and chemical synthesis.However,the compacted manufacturing,massive energy input and the release of tremendous wastes have restricted commercialization feasibility.Regards to mitigate such issues,the photocatalytic H_(2)O_(2)production by utilizing g-C_(3)N_(4)catalysts has endowed a greener,sustainable and promising alternative,considering that it involves water and oxygen as reactants in the present of sunlight as energy input.Herein,we have manifested a comprehensive overview of the research progress for g-C_(3)N_(4)-based semiconductors for photocatalytic H_(2)O_(2)generation.This review has systematically elucidated state-of-the-art development of different modifications on g-C_(3)N_(4)to unravel the fundamental mechanism of H_(2)O_(2)evolution via oxygen reduction reaction(ORR)and water oxidation reaction(WOR).In addition,the contribution made by vacancy introduction,doping,heterogenization,and co-catalyst passivation with respect to photoefficiency enhancement have been clarified.Furthermore,the current challenges and perspective of future development directions on photocatalytic H_(2)O_(2)production have also been highlighted.As such,g-C_(3)N_(4)stands as the next step toward advancement in the configuration and modulation of high-efficiency photocatalysts.
基金supported by the National Natural Science Foundation of China(Nos.21977058 and 82473840)the Key R&D Program of Jiangsu Province(No.BE2021677)+2 种基金China Postdoctoral Science Foundation(No.2018T110533)the Key Natural Science Foundation of Jiangsu Higher Education Institutions(No.20KJA350002)Jiangsu Province Innovation Project of Postgraduate Training(No.KYCX22_3380).
文摘Ischemic stroke(IS)presents a major threat to human life and health due to its high disability and mortality rates.3-n-Butylphthalide(NBP),derived from celery seeds of the Apiaceae family native to the Mediterranean region,was first introduced in China for acute IS treatment in 2004.NBP demonstrates multiple therapeutic actions,including reconstruction of microcirculation in the cerebral ischemia area,inhibition of platelet aggregation,reduction of cerebral infarction volume,maintenance of blood-brain barrier(BBB)integrity,and enhancement of cerebral blood perfusion.However,its overall efficacy remains moderate,limited by poor water solubility and low bioavailability,which constrains its clinical application.To address these limitations,researchers have actively pursued the development of NBP derivatives and analogs,achieving notable progress.These efforts,including substituent introduction,ring opening derivatization,esterification,and atom substitution,have generated diverse NBP derivatives.Several of these derivatives have advanced to clinical studies.Specifically,potassium 2-(1-hydroxypentyl)-benzoate(PHPB),brozopentyl sodium(BZP),and XY-03-EA(ZONK1103)have reached phase II clinical trials,while(S)-2-(1-acetoxypentyl)benzoic acid L-arginine salt(AAPB)has received clinical trial approval for 2024.This review examines the structural modification and optimization of NBP over the past two decades from a medicinal chemistry perspective,aiming to facilitate the development of superior derivatives and advance cerebral ischemia treatment.
基金supported by the Science Foundation of National Key Laboratory of Science and Technology on Advanced Composites in Special Environmentsthe National Natural Science Foundation of China (No.12002109)+1 种基金sponsored by Natural Science Foundation of Chongqing, China (Nos.CSTC2021jcyj-msxm X10305, CSTB2022NSCQMSX0246, CSTB2022NSCQ-MSX0242, CSTB2022NSCQMSX1244, CSTB2022NSCQ-MSX0441, CSTB2022NSCQMSX1356, CSTB2022NSCQ-MSX1572, CSTB2022NSCQ-MSX1583, CSTB2022NSCQ-MSX0487, CSTB2022TFII-OFX0034)Chongqing Technology Innovation and Application Development Special Key Project (No.CSTB2023TIAD-KPX0010)。
文摘High-temperature proton exchange membranes(HT-PEMs) possess excellent thermal and outstanding electrochemical stability, providing an avenue to realize high-temperature proton exchange membranes fuel cells(HT-PEMFCs) with both superior power density and long-term durability. Unfortunately, polybenzimidazole(PBI), a typical material for conventional HT-PEMs, fails to compromise the high nonaqueous proton conductivity and high mechanical properties, thus hindering their practical applications.Achieving efficient nonaqueous proton conduction is crucial for HT-PEMFC, and many insightful research works have been done in this area. However, there still lacks a report that integrates the host-vip interactions of phosphoric acid doping and the structural stability of polymers to systematically illustrate modification strategies. Here, we summarize recent advancements in enhancing the nonaqueous proton conduction of HT-PEMs. Various polymer structure modification strategies, including main chain and side group modification, cross-linking, blocking, and branching, are reviewed. Composite approaches of polymer, including compounding with organic porous polymers, filling the inorganic components and modifying with ionic liquids, etc., are also covered in this work. These strategies endow the HT-PEMs with more free volume, nanophase-separated structure, and multi-stage proton transfer channels, which can facilitate the proton transportation and improve their performance. Finally, current challenges and future directions for further enhancements are also outlined.
文摘Aim To afford an environmentally benign catalytic epoxidation of carbon-carbon double bonds in organic substrates using hydrogen peroxide as an oxidant and iodine as a catalyst.Method The effects of different factors on the epoxidation of three unsaturated natural products were investigated by orthogonal design.Results The experimental results show that three unsaturated natural products are oxidized to the corresponding epoxides with hydrogen peroxide in the presence of 10%(mol/mol) of iodine at room temperature in high yields.Conclusion Iodine was found to be an efficient catalyst for the epoxidation of carbon-carbon double bonds in some unsaturated natural products with hydrogen peroxide at room temperature.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61264008 and 61274121the Natural Science Foundation of Jiangsu Province under Grant No BK2012829
文摘Regulation of optical properties and electronic structure of graphitic carbon nitride （g-C3N4 ） via external strain has attracted much attention due to its potential in photocatalyst and electronic devices. However, the identifi- cation of g-C3N4 structure transformation induced by strain is greatly lacking. In this work, the Raman spectra of g-C3N4 with external strain are determined theoretically based on the density function theory. Deformation induced by external strain not only regulates the Raman mode positions but also leads to a I^aman mode split- ting, which can be ascribed to crystal symmetry destruction by strain engineering. Our results suggest the use of Raman scattering in structural identification in deformed 9-C3N4 structure.
基金Supported by the National High Technology Research and Development Program(2001AA261161) of China(863 Program).
文摘Objective To study mechanism of various effects of HLA antigen camouflaged by differentmPEGs. Methods Effects of the modification of HLA antigen camouflaged by various mPEGs were detected by microlymphocytotoxicity test. The ability of modification was detected by SDS-PAGE. The mechanism of the modification was depicted by the three-dimensional structure of HLA antigen. Results The specific reaction between HLA-A2 antigen and its antibody were completely blocked by mPEG-BTC and mPEG-SPA. mPEG-MAL did not camouflage HLA antigen. The diversity of the modification of HLA antigen camouflaged by varied mPEGs was closely associated with the amides displayed on the surface of HLA antigen. Conclusion Only the amides which were exposed to the surface of HLA antigen can be camouflaged by mPEG. The amides on the surface of three-dimensional structure of HLA-A2 antigen determine the effect of the modification by various mPEGs.
