Using the specially designed mechanochemical ball-mill equipment, ultramicro molybdenum nitride powders were prepared from pure molybdenum powders in ammonia atmosphere at room temperature by high-energy ball milling....Using the specially designed mechanochemical ball-mill equipment, ultramicro molybdenum nitride powders were prepared from pure molybdenum powders in ammonia atmosphere at room temperature by high-energy ball milling. The structure and the particle size of the powders were investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and transmission electron microscopy （TEM）. The results show that the mass ratio of grinding media to powder was 8：1, after milling for 30 h the Mo2N of fcc structure was obtained, and the average particle size of the powders was around 100 nm. It is found that the chemisorption of ammonia onto the fresh molybdenum surfaces created by milling was the predominant process during solid-gas reaction, and the energy input due to introduction of highly dense grain boundaries and lattice defects offered the activation energy for the transition from Mo-N chemisorption to molybdenum nitride. In addition, the change of Mo electronic undersaturation induced by the grain refining accelerated the bonding between Mo and N. The mechanism model of whole nitriding reaction was given, During the high-energy ball milling processing, the rotational speed of milling played a critical role in determining the overall reaction speed.展开更多
Magnesium-ferrum layered double hydroxide （Mg-Fe-LDH） and zinic-aluminum layered double hydroxide （Zn-A1-LDH） compounds were prepared through a mechanochemical method. The influence of molar ratio of M2＋ to M3＋ ...Magnesium-ferrum layered double hydroxide （Mg-Fe-LDH） and zinic-aluminum layered double hydroxide （Zn-A1-LDH） compounds were prepared through a mechanochemical method. The influence of molar ratio of M2＋ to M3＋ （R value） on the property ofLDH nanoparticles has been studied and the results showed that R=3 ： 1 is the optimum value for the both samples. Besides pure water, the mixture of water and ethanol with the volume ratio of 3 ; 1 is also used to wash the precipitates and used as suspending agent during the peptization process and our results showed that the addition of ethanol can improve the monodispersity of LDH nanoparticles greatly.展开更多
In recent years,mechanochemical method has received attention in the field of degrading pollutants,especially for persistent organic pollutants.In this study,peroxymonosulfate(PMS)as a co-grinding reagent,coupled with...In recent years,mechanochemical method has received attention in the field of degrading pollutants,especially for persistent organic pollutants.In this study,peroxymonosulfate(PMS)as a co-grinding reagent,coupled with contaminated soil were placed in a ball mill for mechanochemical reaction.Through investigating the influences of ball-milling parameters on the degradation efficiency,the reaction conditions were optimized.Under the optimal condition(mass ratio of soil to oxidant is 10:1,mass ratio of ball to material is 30:1,rotation speed of ball mill is 400 rpm),more than 98%phenanthrene(PHE)in contaminated soil could be degraded within 4 h.Meanwhile,the effects of soil organic matter content and soil type on the degradation efficiency were investigated.The results showed that the organic matter content was negatively correlated with the degradation efficiency.XPS analysis provided evidence for the breakage of the CeC bond and confirmed that Fe in soil was an important factor in activating PMS.XRD further verified the destruction of PHE structure.GC-MS analysis was performed to identify the intermediates and possible pathways were proposed.展开更多
Al2O3-CeO2 supports containing 1-10 wt%Ce were prepared mechanochemically by milling aluminum and/or cerium nitrates with NH4HCO3.Heteropolymolybdate,（NH4）4NiMo6O（24）,was used as the precursor of the Ni and Mo to ...Al2O3-CeO2 supports containing 1-10 wt%Ce were prepared mechanochemically by milling aluminum and/or cerium nitrates with NH4HCO3.Heteropolymolybdate,（NH4）4NiMo6O（24）,was used as the precursor of the Ni and Mo to prepare NiMo6/Al2O3-CeO2 components in catalysts by impregnation method.The physicochemical properties of the catalysts were determined using chemical analysis,X-ray diffraction,temperature-programmed H2 reduction,temperature-programmed NH3 desorption,X-ray photoelectron spectroscopy（XPS）,and the Brunauer-Emmett-Teller method.The catalyst acidity decreased with increasing Ce concentration in the support.XPS showed that the NiS/MoS ratio decreased two-fold for the Ce-modified alumina support.NiMo6/Al2O3,which had the highest acidity,showed the highest activity in hydrodesulfurization of 1-benzothiophene（normalized per weight of catalyst）.The concentration of surface MoOxSy species（which is equal to the concentration of Mo^（5＋）） gradually decreased to zero for catalysts with Ce concentrations 10 wt%.However,the activities of all the catalysts prepared mechanochemically from Al2O3 and Al2O3-CeO2supports significantly exceeded that of a reference NiMo6/Al2O3 catalyst prepared by impregnation method using the same precursor and with the same composition.展开更多
Burrs generated during the machining of Aramid-Fiber-Reinforced Composites(AFRPs)pose a challenge for the production efficiency of aircraft and helicopter housing parts.Existing studies have generally attempted to sup...Burrs generated during the machining of Aramid-Fiber-Reinforced Composites(AFRPs)pose a challenge for the production efficiency of aircraft and helicopter housing parts.Existing studies have generally attempted to suppress burrs by referring to delamination suppression methods.In contrast to stratification,burrs are remediable machining defects.As such,a mechanochemical method with burrs trimming technological strategy are implemented to effectively combat burrs.Herein,we clarify the mechanism by which aramid fibers cannot be cut off using analytical and numerical models.In addition,the mechanism of fiber fracture with Modified Polyurethane Reactive Polymer(M-PUR),and development of anti-burr devices(thermostatic adhesive sealed generator)are discussed.Finally,the experimental results show that the reduction rate in burr length is 87%-91%through the mechanochemical method.The method not only opens a new avenue to solve the burr problem of aramid fibers but also builds an interdisciplinary bridge between polymer science and composite machining.展开更多
Through the mechanochemical method,sulfamic acid(SA)is successfully introduced into UiO-66-NH_(2)to form SA@UiO-66-NH_(2).In SA@UiO-66-NH_(2),the acidic cationic sulfiliminium(—S=NH_(2)^(+))moiety formed by the bridg...Through the mechanochemical method,sulfamic acid(SA)is successfully introduced into UiO-66-NH_(2)to form SA@UiO-66-NH_(2).In SA@UiO-66-NH_(2),the acidic cationic sulfiliminium(—S=NH_(2)^(+))moiety formed by the bridging bidentate binding mode between SA and the zirconium metal center can release protons,and SA actively participates in the construction of hydrogen-bonded network,thereby accelerating the proton conduction.At 95%RH(relative humidity)and 358 K,the proton conductivity of SA@UiO-66-NH_(2)can reach 1.42×10^(-2)S·cm^(-1),which is four orders of magnitude higher than that of the parent framework UiO-66-NH_(2).Meanwhile,this high proton conductivity can be maintained for at least 90 h.展开更多
Radiation therapy(RT)that utilizes high dose of ionizing radiation to kill tumor cells is a common cancer treatment method.However,the effectiveness of RT is limited by the tolerance of normal tissue surrounding the t...Radiation therapy(RT)that utilizes high dose of ionizing radiation to kill tumor cells is a common cancer treatment method.However,the effectiveness of RT is limited by the tolerance of normal tissue surrounding the tumor.Using high atom number(Z)element-based radio sensitizers to increase energy deposit inside tumor cells can achieve better carcinoma killing.Tantalum nanoparticles(Ta NPs)exhibit good radiotherapy sensitization effects.However,achieving the water solubility of Ta NPs is challenging.This study reported a mechanochemical method for obtaining Ta NPs modified with sodium hexametaphosphate(SHMP)for radiotherapy sensitization applications.The results showed that the water solubility of Ta NPs modified with SHMP was significantly improved.Their biocompatibility and radio sensitizing ability are also verified at both cellular and animal levels.展开更多
文摘Using the specially designed mechanochemical ball-mill equipment, ultramicro molybdenum nitride powders were prepared from pure molybdenum powders in ammonia atmosphere at room temperature by high-energy ball milling. The structure and the particle size of the powders were investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and transmission electron microscopy （TEM）. The results show that the mass ratio of grinding media to powder was 8：1, after milling for 30 h the Mo2N of fcc structure was obtained, and the average particle size of the powders was around 100 nm. It is found that the chemisorption of ammonia onto the fresh molybdenum surfaces created by milling was the predominant process during solid-gas reaction, and the energy input due to introduction of highly dense grain boundaries and lattice defects offered the activation energy for the transition from Mo-N chemisorption to molybdenum nitride. In addition, the change of Mo electronic undersaturation induced by the grain refining accelerated the bonding between Mo and N. The mechanism model of whole nitriding reaction was given, During the high-energy ball milling processing, the rotational speed of milling played a critical role in determining the overall reaction speed.
基金This work was supported by National Natural Science Foundation of China （No. 21073093） and Doctoral Fund of Ministry of Education of China （No. 20103207120006） and Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘Magnesium-ferrum layered double hydroxide （Mg-Fe-LDH） and zinic-aluminum layered double hydroxide （Zn-A1-LDH） compounds were prepared through a mechanochemical method. The influence of molar ratio of M2＋ to M3＋ （R value） on the property ofLDH nanoparticles has been studied and the results showed that R=3 ： 1 is the optimum value for the both samples. Besides pure water, the mixture of water and ethanol with the volume ratio of 3 ; 1 is also used to wash the precipitates and used as suspending agent during the peptization process and our results showed that the addition of ethanol can improve the monodispersity of LDH nanoparticles greatly.
基金Beijing Municipal Natural Science Foundation-Beijing Academy of Science and Technology jointly funded project(Project No.16L00073).
文摘In recent years,mechanochemical method has received attention in the field of degrading pollutants,especially for persistent organic pollutants.In this study,peroxymonosulfate(PMS)as a co-grinding reagent,coupled with contaminated soil were placed in a ball mill for mechanochemical reaction.Through investigating the influences of ball-milling parameters on the degradation efficiency,the reaction conditions were optimized.Under the optimal condition(mass ratio of soil to oxidant is 10:1,mass ratio of ball to material is 30:1,rotation speed of ball mill is 400 rpm),more than 98%phenanthrene(PHE)in contaminated soil could be degraded within 4 h.Meanwhile,the effects of soil organic matter content and soil type on the degradation efficiency were investigated.The results showed that the organic matter content was negatively correlated with the degradation efficiency.XPS analysis provided evidence for the breakage of the CeC bond and confirmed that Fe in soil was an important factor in activating PMS.XRD further verified the destruction of PHE structure.GC-MS analysis was performed to identify the intermediates and possible pathways were proposed.
基金Czech Science Foundation(Project P106/11/0902) for financial support
文摘Al2O3-CeO2 supports containing 1-10 wt%Ce were prepared mechanochemically by milling aluminum and/or cerium nitrates with NH4HCO3.Heteropolymolybdate,（NH4）4NiMo6O（24）,was used as the precursor of the Ni and Mo to prepare NiMo6/Al2O3-CeO2 components in catalysts by impregnation method.The physicochemical properties of the catalysts were determined using chemical analysis,X-ray diffraction,temperature-programmed H2 reduction,temperature-programmed NH3 desorption,X-ray photoelectron spectroscopy（XPS）,and the Brunauer-Emmett-Teller method.The catalyst acidity decreased with increasing Ce concentration in the support.XPS showed that the NiS/MoS ratio decreased two-fold for the Ce-modified alumina support.NiMo6/Al2O3,which had the highest acidity,showed the highest activity in hydrodesulfurization of 1-benzothiophene（normalized per weight of catalyst）.The concentration of surface MoOxSy species（which is equal to the concentration of Mo^（5＋）） gradually decreased to zero for catalysts with Ce concentrations 10 wt%.However,the activities of all the catalysts prepared mechanochemically from Al2O3 and Al2O3-CeO2supports significantly exceeded that of a reference NiMo6/Al2O3 catalyst prepared by impregnation method using the same precursor and with the same composition.
基金supported by the National Natural Science Foundation of China(No.52275441)Shenzhen Science and Technology Program,China(No.WDZC20231129101903002).
文摘Burrs generated during the machining of Aramid-Fiber-Reinforced Composites(AFRPs)pose a challenge for the production efficiency of aircraft and helicopter housing parts.Existing studies have generally attempted to suppress burrs by referring to delamination suppression methods.In contrast to stratification,burrs are remediable machining defects.As such,a mechanochemical method with burrs trimming technological strategy are implemented to effectively combat burrs.Herein,we clarify the mechanism by which aramid fibers cannot be cut off using analytical and numerical models.In addition,the mechanism of fiber fracture with Modified Polyurethane Reactive Polymer(M-PUR),and development of anti-burr devices(thermostatic adhesive sealed generator)are discussed.Finally,the experimental results show that the reduction rate in burr length is 87%-91%through the mechanochemical method.The method not only opens a new avenue to solve the burr problem of aramid fibers but also builds an interdisciplinary bridge between polymer science and composite machining.
基金supported by the National Natural Science Foundation of China(22071019 and 21872021)the Basic Scientific Research Project of Liaoning Provincial Department of Education(LJKMZ20220968)
文摘Through the mechanochemical method,sulfamic acid(SA)is successfully introduced into UiO-66-NH_(2)to form SA@UiO-66-NH_(2).In SA@UiO-66-NH_(2),the acidic cationic sulfiliminium(—S=NH_(2)^(+))moiety formed by the bridging bidentate binding mode between SA and the zirconium metal center can release protons,and SA actively participates in the construction of hydrogen-bonded network,thereby accelerating the proton conduction.At 95%RH(relative humidity)and 358 K,the proton conductivity of SA@UiO-66-NH_(2)can reach 1.42×10^(-2)S·cm^(-1),which is four orders of magnitude higher than that of the parent framework UiO-66-NH_(2).Meanwhile,this high proton conductivity can be maintained for at least 90 h.
基金supported by the National Key R&D Program of China(Nos.2020YFA0710702 and 2021YFA1201200)the National Science Foundation of China(Nos.22375205,51705295 and 52103337)+3 种基金Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB36000000)Directional Institutionalized Scientific Research Platform relies on Beijing Synchrotron Radiation Facility of Chinese Academy of Sciences,Beijing Natural Science Foundation(No.2222087)Shandong Provincial Natural Science Foundation of China(ZR2022ME032)the Support Program for Youth Innovation Technology in Colleges and Universities of Shandong Province(2019KJB015)。
文摘Radiation therapy(RT)that utilizes high dose of ionizing radiation to kill tumor cells is a common cancer treatment method.However,the effectiveness of RT is limited by the tolerance of normal tissue surrounding the tumor.Using high atom number(Z)element-based radio sensitizers to increase energy deposit inside tumor cells can achieve better carcinoma killing.Tantalum nanoparticles(Ta NPs)exhibit good radiotherapy sensitization effects.However,achieving the water solubility of Ta NPs is challenging.This study reported a mechanochemical method for obtaining Ta NPs modified with sodium hexametaphosphate(SHMP)for radiotherapy sensitization applications.The results showed that the water solubility of Ta NPs modified with SHMP was significantly improved.Their biocompatibility and radio sensitizing ability are also verified at both cellular and animal levels.
