The timings and geodynamic controls of Mo,Au,and Au-Mo deposits in the Xiaoqinling Orogen(>630 t Au and 115,000 t Mo),a rare Au-Mo province globally,are addressed by a combination of mineral par-ageneses,crystallin...The timings and geodynamic controls of Mo,Au,and Au-Mo deposits in the Xiaoqinling Orogen(>630 t Au and 115,000 t Mo),a rare Au-Mo province globally,are addressed by a combination of mineral par-ageneses,crystalline mineralogy,geochemistry,and Re-Os and U-Pb geochronology in the Dahu,Qinnan,and Yangzhaiyu deposits.The Xiaoqinling Orogen comprises an E-W-trending fold and thrust system with repeated structural reactivation and the Mo or Au orebodies in these deposits are dominantly controlled by E-W-trending and NW-SE-trending shear zones.Molybdenum mineralization related to K-feldspar alteration comprises early molybdenite,pyrite,rutile,and monazite within gray quartz veins plus late molybdenite and pyrite within white quartz veins in the Dahu and Qinnan Au-Mo deposits.Early and late Au mineralization events have similar mineral assemblages of pyrite,native gold±Au-Ag-Te minerals,rutile,and monazite associated with quartz-sericite alteration at Yangzhaiyu.The early dissem-inated molybdenite is characterized by rhombohedral polytype and oscillatory Re zoning,in contrast to the late molybdenite with a coexistence of rhombohedral and hexagonal polytypes and irregularly distributed Re.The early molybdenite has a Re-Os isochron age of 222.5±1.3 Ma,compatible with a monazite U-Pb age of 224±6.1 Ma,whereas late molybdenite provides a Re-Os isochron age of 185.0±12 Ma,with the implication that the 3R-polytype molybdenite with oscillatory Re zoning is more suitable for high-precision dating.The early and late Au mineralization have a pyrite Re-Os age of 202.0±5.9 Ma and U-Pb age of 124.0±1.3 Ma,respectively.In accordance with its complex geodynamic setting,geological and geochronological studies record a complicated 100-million-year mineralization history with multiple magmatic-hydrothermal Mo and orogenic Au mineralization events that formed within a structural framework of multiply reactivated shear zones.展开更多
Projectiles made of reactive structure materials(RSM)can damage the target with not only kinetic but also chemical energy,but the enhanced damage potential of RSM may become compromised if extreme loading condition di...Projectiles made of reactive structure materials(RSM)can damage the target with not only kinetic but also chemical energy,but the enhanced damage potential of RSM may become compromised if extreme loading condition disintegrates the projectile before the target is reached.In this work,a ductile coating of Ni was introduced to a tungsten-zirconium(W-Zr)alloy,a typical brittle RSM,to preserve the damage potential of the projectile.Detonation driving tests were carried out with X-ray photography and gunpowder deflagration driving tests were carried out with high-speed photography for the coated and uncoated RSM samples,respectively.The craters on the witness target were analyzed by scanning electron microscopy and X-ray diffraction.The Ni coating was found to effectively preserve the damage potential of the W-Zr alloy under extreme loading conditions,whereas the uncoated sample fractured and ignited before impacting the target in both detonation and deflagration driving.The crack propagation between the reactively brittle core and the ductile coating was analyzed based on the crack arrest theory to mechanistically demonstrate how the coating improves the structural integrity and preserves the damage potential of the projectile.Specifically,the Ni coating envelops theW-Zr core until the coated sphere penetrates the target,and the coating is then eroded and worn to release the reactive core for the projectile to damage the target more intensively.展开更多
The relationships between the structure of oxime compounds(R^(1)R^(2)C=NOH,R^(1)/R^(2)=alkyl groups) with different substituents and their corresponding flotation performances were studied. The analyses of density fun...The relationships between the structure of oxime compounds(R^(1)R^(2)C=NOH,R^(1)/R^(2)=alkyl groups) with different substituents and their corresponding flotation performances were studied. The analyses of density functional theory(DFT) calculations illustrated that the introduced phenyl group at the R^(1) position could enhance the acidity,while the heptyl group could effectively increase the hydrophobicity and benefit van der Waals interactions. Meanwhile,the introduced amino group at the R^(2) position could provide cationic sites to interact with negatively charged surfaces of minerals, while the introduced hydroxyl group could provide additional action sites to form stable chelates with metal ions. Based on the structure-activity relationships, structural optimization was carried out to obtain three efficient collectors, which possessed superior flotation separation performances, proving the effectiveness of the structural modification to oxime compounds in this work.展开更多
The interactions of a spherical flame with an incident shock wave and its reflected shock wave in a confined space were investigated using the three-dimensional reactive Navier-Stokes equations, with emphasis placed o...The interactions of a spherical flame with an incident shock wave and its reflected shock wave in a confined space were investigated using the three-dimensional reactive Navier-Stokes equations, with emphasis placed on the effect of chemical reactivity of mixture on the flame distortion and detonation initiation after the passage of the reflected shock wave. It is shown that the spatio-temporal characteristics of detonation initiation depend highly on the chemi- cal reactivity of the mixture. When the chemical reactivity enhances, the flame can be severely distorted to form a reactive shock bifurcation structure with detonations initiating at different three-dimensional spatial locations. Moreover, the detonation initiation would occur earlier in a mixture of more enhanced reactivity. The results reveal that the detona- tions arise from hot spots in the unburned region which are initiated by the shock-detonation-transition mechanism.展开更多
Molecular structures of reactants were characterized by molecular electronegativity distance vector （VHMED） considering hydrogen association. A reasonable molecular modeling equation with 4-parameters was achieved f...Molecular structures of reactants were characterized by molecular electronegativity distance vector （VHMED） considering hydrogen association. A reasonable molecular modeling equation with 4-parameters was achieved for quantitative structure-property/activity relationship （QSPR/QSAR） by stepwise multiple regression （SMR） that the variable was introduced item by item in significant level order. A high correlation coefficient （R = 0.980） demonstrates that the model is able to well express a quantitative relation between stereoselectivity and the reactant structures as quantitative structure-reactivity/stereoselectivity relationship （QSRR/QSSR）. The multiple correlation coefficient （Rcv= 0.964） was tested through cross-validation with the leave-one-out （LOO） procedure. The above results show that the model possesses high estimation stability and good prediction ability between the amount of both cis and trans isomers in products and reactants.展开更多
In light of the accelerated aging of the global population and the deterioration of the atmosphere pollution, we sought to clarify the potential mechanisms by which fine particulate matter（PM_（2.5）） can cause cogn...In light of the accelerated aging of the global population and the deterioration of the atmosphere pollution, we sought to clarify the potential mechanisms by which fine particulate matter（PM_（2.5）） can cause cognitive impairment and neurodegeneration through the alteration of mitochondrial structure and function. The results indicate that PM_（2.5） inhalation reduces ATP production by disrupting the aerobic tricarboxylic acid cycle and oxidative phosphorylation, thereby causing the hypophosphorylation of tau in the cortices of middle-aged mice. Furthermore, excessive reactive oxygen species generation was involved in the impairment. Interestingly, these alterations were partially reversed after exposure to PM_（2.5） ended. These findings clarify the mechanism involved in mitochondrial abnormality-related neuropathological dysfunction in response to atmospheric PM_（2.5） inhalation and provide an optimistic sight for alleviating the adverse health outcomes in polluted areas.展开更多
Transient electronics are an emerging class of electronics with the unique characteristic to completely dissolve within a programmed period of time. Since no harmful byproducts are released, these electronics can be u...Transient electronics are an emerging class of electronics with the unique characteristic to completely dissolve within a programmed period of time. Since no harmful byproducts are released, these electronics can be used in the human body as a diagnostic tool, for instance, or they can be used as environmentally friendly alternatives to existing electronics which disintegrate when exposed to water. Thus, the most crucial aspect of transient electronics is their ability to disintegrate in a practical manner and a review of the literature on this topic is essential for understanding the current capabilities of transient electronics and areas of future research. In the past, only partial dissolution of transient electronics was possible, however, total dissolution has been achieved with a recent discovery that silicon nanomembrane undergoes hydrolysis. The use of single- and multi-layered structures has also been explored as a way to extend the lifetime of the electronics. Analytical models have been developed to study the dissolution of various functional materials as well as the devices constructed from this set of functional materials and these models prove to be useful in the design of the transient electronics.展开更多
We have generated one possible active site structure of Oxyhemocyanin (Oxy-Hc) and two possible active site structures of Oxytyrosinase (Oxy-Ty) using the EHMO method. Oxy-Hc active site has a plane configuration, whi...We have generated one possible active site structure of Oxyhemocyanin (Oxy-Hc) and two possible active site structures of Oxytyrosinase (Oxy-Ty) using the EHMO method. Oxy-Hc active site has a plane configuration, while Oxy-Ty has boat configuration. When there exist water molecules, two water molecules are connected with the Oxy-Ty active site weakly. Calculations for the reactions of Oxy-Hc and Oxy-Ty (the water-off) with phenol demonstrate that the former reaction is thermodynamically forbidden, while the latter Is realizable.展开更多
Background： Toasting during the production of rapeseed meal（RSM） decreases ileal crude protein（CP） and amino acid（AA） digestibility. The mechanisms that determine the decrease in digestibility have not been ful...Background： Toasting during the production of rapeseed meal（RSM） decreases ileal crude protein（CP） and amino acid（AA） digestibility. The mechanisms that determine the decrease in digestibility have not been fully elucidated. A high protein quality, low-denatured, RSM was produced and toasted up to 120 min, with samples taken every 20 min. The aim of this study was to characterize secondary structure and chemical changes of proteins and glucosinolates occurring during toasting of RSM and the effects on its in vitro CP digestibility.Results： The decrease in protein solubility and the increase of intermolecular β-sheets with increasing toasting time were indications of protein aggregation. The contents of NDF and ADIN increased with increasing toasting time.Contents of arginine, lysine and O-methylisourea reactive lysine（OMIU-RL） linearly decreased with increasing toasting time, with a larger decrease of OMIU-RL than lysine. First-order reactions calculated from the measured parameters show that glucosinolates were degraded faster than lysine, OMIU-RL and arginine and that physical changes to proteins seem to occur before chemical changes during toasting. Despite the drastic physical and chemical changes noticed on the proteins, the coefficient of in vitro CP digestibility ranged from 0.776 to 0.750 and there were no effects on the extent of protein hydrolysis after 120 min. In contrast, the rate of protein hydrolysis linearly decreased with increasing toasting time, which was largely correlated to the decrease in protein solubility, lysine and OMIU-RL observed. Rate of protein hydrolysis was more than 2-fold higher for the untoasted RSM compared to the 120 min toasted material.Conclusions： Increasing the toasting time for the production of RSM causes physical and chemical changes to the proteins that decrease the rate of protein hydrolysis. The observed decrease in the rate of protein hydrolysis could impact protein digestion and utilization.展开更多
Based on an advanced technology, randomly-aligned subwavelength structures（SWSs） were obtained by a metal-nanodot-induced one-step self-masking reactive-ion-etching process on a fused silica surface. Metal-fluoride...Based on an advanced technology, randomly-aligned subwavelength structures（SWSs） were obtained by a metal-nanodot-induced one-step self-masking reactive-ion-etching process on a fused silica surface. Metal-fluoride（mainly ferrous-fluoride） nanodots induce and gather stable fluorocarbon polymer etching inhibitors in the reactive-ion-etching polymers as masks. Metal fluoride（mainly ferrous fluoride） is produced by the sputtering of argon plasma and the ion-enhanced chemical reaction of metal atoms. With an increase in CHF_3/Ar gas flow ratio, the average height of the SWSs increases, the number of SWSs per specific area increases and then decreases, and the optical transmittance of visible light increases and then decreases. The optimum CHF_3/Ar gas flow ratio for preparing SWSs is 1：5.展开更多
Porous Fe-Sialloys with different nominalcompositions ranging from Fe-10wt% Sito Fe-50wt% Siwere fabricated through a reactive synthesis of Fe and Sielementalpowder mixtures.The effects of Sicontents on the pore struc...Porous Fe-Sialloys with different nominalcompositions ranging from Fe-10wt% Sito Fe-50wt% Siwere fabricated through a reactive synthesis of Fe and Sielementalpowder mixtures.The effects of Sicontents on the pore structure of porous Fe-Sialloy were investigated in detail.The results showed that the open porosity,gas permeability and maximum pore size of the porous Fe-Sialloys increased with increasing Sicontents,indicating that the porosity and pore size can be tailored by changing the Sicontents.The pore structure parameter including the open porosity,gas permeability,maximum pore size obeyed the HagenPoiseuille formula with the constant G=0.035 m^（-1_Pa^（-1）s^（-1） for the reactively synthesized porous Fe-Sialloys.The mechanicalproperty of the porous Fe-Sialloys showed applicability in the filtration industries.展开更多
The reactivity of carbonyl iron cluster with alkynes has been studied by the thermal reaction of Fe_3（CO）_（12） with R-C≡C-R＇（R = Fc（Ferrocenyl）; R′ = Ph（Phenyl）, Fc, H）. The hexacarbonyldiiron cluster wit...The reactivity of carbonyl iron cluster with alkynes has been studied by the thermal reaction of Fe_3（CO）_（12） with R-C≡C-R＇（R = Fc（Ferrocenyl）; R′ = Ph（Phenyl）, Fc, H）. The hexacarbonyldiiron cluster with ferracyclopentadiene ring（μ_2, η~4-C_4Ph_4）Fe_2（CO）_6（1） and one tetraphenyl substituted cyclopentadienone（Ph_4C_4CO）（2） were simultaneously obtained by the reaction of Fe_3（CO）_（12） with alkyne（Ph-C≡C-Ph）. Only one ferrole cluster（μ_2, η~4-C_4Fc_2H_2）Fe_2（CO）_6（3） was separated by using Fc-C≡C-H as alkyne. One tri-carbonyl iron complex（η~4-C_4Fc_4CO）Fe（CO）_3（4） and an unexpected new cyclic ketone compound 2,2,4,5-tetraferrocenylcyclopenta-4-en-1,3-di-one [Fc_4C_3（CO）_2]（5） were obtained by using Fc-C≡C-Fc as alkyne. A new complex（η4-2,4-diphenyl-3,5-diferrocenylcyclopenta-2,4-dien-1-one）-tricarbonyl iron（η~4-C_4Ph_2Fc_2CO）Fe（CO）_3（6） was synthesized by the reaction of Fe_3（CO）_（12） with Fc-C≡C-Ph. The structures of compounds 1~6 were determined by X-ray single-crystal diffraction and spectroscopic characterization. The crystal structures of two new compounds 5 and 6 were analyzed. Our experimental results reveal the structural models of the reaction products are affected by the kinds of substituents from alkynes R-C≡C-R′.展开更多
Cerium-aluminum(CeAl)alloy is promising reactive structural materials(RSMs)with significant potential for liner applications.To investigate the thermochemical characteristics of CeAl alloy and the perforation behavior...Cerium-aluminum(CeAl)alloy is promising reactive structural materials(RSMs)with significant potential for liner applications.To investigate the thermochemical characteristics of CeAl alloy and the perforation behavior of its liner impacting steel targets,a CeAl alloy liner with 5 wt%Al content was fabricated,with a cerium(Ce)liner and a copper(Cu)liner used as control.The microstructure and elemental distribution of the CeAl alloy were analyzed using SEM,EDS,and XRD.The thermochemical reaction mechanism of the CeAl alloy was examined through TG-DSC.Penetration experiments were conducted to explore the combined effects of invasion and implosion of CeAl alloy liner against steel target.The results indicate that the addition of Al leads to the formation of Ce_(3)Al intermetallic compounds in the alloy and reduces the apparent activation energy of the Ce-based alloy by around 53.17%,thereby facilitating energy release.The presence of 5 wt%Al increases the calorific value by approximately 24.5%,and this change allows the oxidation process to be divided into three distinct stages.Compared to an inert copper liner,the average penetration diameter of the CeAl_(5) reactive alloy liner increases by around 42.78%.Furthermore,when compared to the Ce liner,the penetration depth of the CeAl_(5) reactive alloy liner increases by approximately 82.64%.展开更多
Intraplate structural deformation is diagnostic of tectonic stress regime changes linked to plate interactions and can result from superposed tectonic events whose single contributions are hardly distinguishable.In th...Intraplate structural deformation is diagnostic of tectonic stress regime changes linked to plate interactions and can result from superposed tectonic events whose single contributions are hardly distinguishable.In this paper,we present a set of integrated thermochronologic inverse models along a 140 km-long transect across the central Greater Caucasus and the adjacent Adjara-Trialeti fold-and-thrust belt of Georgia,two intraplate orogens produced by structural inversion of parallel continental rift zones located on the Eurasian plate.Our dataset allows to distinguish discrete and superposed deformation episodes and quantify their respective contributions to orogenic exhumation.The integration of(U-Th)/He analysis on apatite and zircon,fission-track analysis on apatite,and peak-temperature determinations(clay mineralogy,organic matter petrography,Raman spectroscopy)shows that structural inversion was punctuated by two incremental steps starting respectively in the latest Cretaceous and the mid-Miocene.Latest Cretaceous partial inversion of the Greater Caucasus is documented here for the first time and placed in a geographically wider context of coeval deformation.The two episodes of intraplate structural inversion,exhumation,and sediment generation are chronologically and physically correlated with docking of(i)the Anatolide-Tauride-Armenian terrane(Late Cretaceous-Paleocene)and(ii)Arabia(Miocene hard collision)against the southern Eurasian plate margin.Intraplate deformation in the Caucasian domain was triggered by far-field propagation of plate-margin collisional stress which focused preferentially along rheologically weak rift zones.展开更多
Drug innovation is characterized by painstaking molecular-level syntheses and modifications as the basic components of research and development.Similarly,natural products are chemically tailored and modified based upo...Drug innovation is characterized by painstaking molecular-level syntheses and modifications as the basic components of research and development.Similarly,natural products are chemically tailored and modified based upon their structural and biological properties.To some extent,the modification of natural products is quite different from de novo structure-based drug discovery.This review describes the general strategies and principles for the modification of natural products to drugs,as illustrated by several successful medicines that originated from natural products.展开更多
The physiochemical properties of chars produced by coal pyrolysis in a laboratory-scale fluidized bed reactor with a continuous coal feed and char discharge at temperatures of 750 to 980 ~ C under N2-based atmospheres...The physiochemical properties of chars produced by coal pyrolysis in a laboratory-scale fluidized bed reactor with a continuous coal feed and char discharge at temperatures of 750 to 980 ~ C under N2-based atmospheres containing 02, H2, CO, CH4, and CO2 were studied. The specific surface area of the char was found to decrease with increasing pyrolysis temperature. The interlayer spacing of the char also decreased, while the average stacking height and carbon crystal size increased at higher temperatures, suggesting that the char generated at high temperatures had a highly ordered structure. The char obtained using an ER value of 0.064 exhibited the highest specific surface area and oxidation reactivity. Rela- tively high 02 concentrations degraded the pore structure of the char, decreasing the surface area. The char produced in an atmosphere incorporating H2 showed a more condensed crystalline structure and consequently had lower oxidation reactivity.展开更多
With the support by the National Natural Science Foundation of China,a collaboration by the research groups led by Prof.Cheng Gang(程纲)from Henan University and Prof.Wang Zhonglin(王中林)from Beijing Institute of Nan...With the support by the National Natural Science Foundation of China,a collaboration by the research groups led by Prof.Cheng Gang(程纲)from Henan University and Prof.Wang Zhonglin(王中林)from Beijing Institute of Nanoenergy and Nanosystems,Chinese Academy of Sciences,invents'a sliding-mode triboelectric nanogenerator with chemical group grated structure by shadow mask reactive ion etching',which was published in ACS Nano(2017,11(9):8796-8803).展开更多
Electronic and bonding situations at reaction centers are often detected by the remote substituent effect.For nonorganometallic reactions,this effect is conventionally described by the well-known Hammett-type substitu...Electronic and bonding situations at reaction centers are often detected by the remote substituent effect.For nonorganometallic reactions,this effect is conventionally described by the well-known Hammett-type substituent constants.However,for most transition metal(TM)-involved systems,no analogous numeral descriptors reflecting the intrinsic differences between metallic and nonmetallic bonding have been rigorously established till present.Herein,we report a Pd(II)–O bond heterolysis energyΔG_(het)(Pd–O)study of the archetypal palladium complexes to represent the thermodynamics of the essential bond-breaking step in Pd-mediated transformations.Meanwhile we furnish the new substituent constantsσPd^(+)s and therefrom facilitate linear free-energy relationship(LFER)analysis for Pd-catalyzed reactions.Indeed,this led us to find an unexpected electron-donating ability of Pd(II)cation,which provided a gifted experimental support,with the aid of computation,to attribute the frustrating observation of a much scattered curvature in theΔG_(het)(Pd–O)-σ+correlation to the electrondonating capacity of the cationic palladium through back-donation of its d-electrons.Applications of LFER analysis withσPd^(+)to predict the redox behavior of the palladium complex and in a kinetics vs.thermodynamicsmechanistic study of transmetalation added further credence to their applicability to TM systems.展开更多
基金supported by the National Key Research and Development Project of China(2020YFA0714802)the National Natural Science Foundation of China(42330809)the 111 Project of the Ministry of Science and Technology(BP0719021).
文摘The timings and geodynamic controls of Mo,Au,and Au-Mo deposits in the Xiaoqinling Orogen(>630 t Au and 115,000 t Mo),a rare Au-Mo province globally,are addressed by a combination of mineral par-ageneses,crystalline mineralogy,geochemistry,and Re-Os and U-Pb geochronology in the Dahu,Qinnan,and Yangzhaiyu deposits.The Xiaoqinling Orogen comprises an E-W-trending fold and thrust system with repeated structural reactivation and the Mo or Au orebodies in these deposits are dominantly controlled by E-W-trending and NW-SE-trending shear zones.Molybdenum mineralization related to K-feldspar alteration comprises early molybdenite,pyrite,rutile,and monazite within gray quartz veins plus late molybdenite and pyrite within white quartz veins in the Dahu and Qinnan Au-Mo deposits.Early and late Au mineralization events have similar mineral assemblages of pyrite,native gold±Au-Ag-Te minerals,rutile,and monazite associated with quartz-sericite alteration at Yangzhaiyu.The early dissem-inated molybdenite is characterized by rhombohedral polytype and oscillatory Re zoning,in contrast to the late molybdenite with a coexistence of rhombohedral and hexagonal polytypes and irregularly distributed Re.The early molybdenite has a Re-Os isochron age of 222.5±1.3 Ma,compatible with a monazite U-Pb age of 224±6.1 Ma,whereas late molybdenite provides a Re-Os isochron age of 185.0±12 Ma,with the implication that the 3R-polytype molybdenite with oscillatory Re zoning is more suitable for high-precision dating.The early and late Au mineralization have a pyrite Re-Os age of 202.0±5.9 Ma and U-Pb age of 124.0±1.3 Ma,respectively.In accordance with its complex geodynamic setting,geological and geochronological studies record a complicated 100-million-year mineralization history with multiple magmatic-hydrothermal Mo and orogenic Au mineralization events that formed within a structural framework of multiply reactivated shear zones.
基金National Natural Science Foundation of China.Grant ID:11872123.
文摘Projectiles made of reactive structure materials(RSM)can damage the target with not only kinetic but also chemical energy,but the enhanced damage potential of RSM may become compromised if extreme loading condition disintegrates the projectile before the target is reached.In this work,a ductile coating of Ni was introduced to a tungsten-zirconium(W-Zr)alloy,a typical brittle RSM,to preserve the damage potential of the projectile.Detonation driving tests were carried out with X-ray photography and gunpowder deflagration driving tests were carried out with high-speed photography for the coated and uncoated RSM samples,respectively.The craters on the witness target were analyzed by scanning electron microscopy and X-ray diffraction.The Ni coating was found to effectively preserve the damage potential of the W-Zr alloy under extreme loading conditions,whereas the uncoated sample fractured and ignited before impacting the target in both detonation and deflagration driving.The crack propagation between the reactively brittle core and the ductile coating was analyzed based on the crack arrest theory to mechanistically demonstrate how the coating improves the structural integrity and preserves the damage potential of the projectile.Specifically,the Ni coating envelops theW-Zr core until the coated sphere penetrates the target,and the coating is then eroded and worn to release the reactive core for the projectile to damage the target more intensively.
基金the support of the National Natural Science Foundation of China(Nos.51774329 and 51904337)the High Performance Computing Center of Central South University,China。
文摘The relationships between the structure of oxime compounds(R^(1)R^(2)C=NOH,R^(1)/R^(2)=alkyl groups) with different substituents and their corresponding flotation performances were studied. The analyses of density functional theory(DFT) calculations illustrated that the introduced phenyl group at the R^(1) position could enhance the acidity,while the heptyl group could effectively increase the hydrophobicity and benefit van der Waals interactions. Meanwhile,the introduced amino group at the R^(2) position could provide cationic sites to interact with negatively charged surfaces of minerals, while the introduced hydroxyl group could provide additional action sites to form stable chelates with metal ions. Based on the structure-activity relationships, structural optimization was carried out to obtain three efficient collectors, which possessed superior flotation separation performances, proving the effectiveness of the structural modification to oxime compounds in this work.
基金supported by the National Natural Science Foundation of China (10972107)Open Fund of State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology (KFJJ12-4Y)Jiangsu Innovation Program for Graduate Education (CXLX11 0271)
文摘The interactions of a spherical flame with an incident shock wave and its reflected shock wave in a confined space were investigated using the three-dimensional reactive Navier-Stokes equations, with emphasis placed on the effect of chemical reactivity of mixture on the flame distortion and detonation initiation after the passage of the reflected shock wave. It is shown that the spatio-temporal characteristics of detonation initiation depend highly on the chemi- cal reactivity of the mixture. When the chemical reactivity enhances, the flame can be severely distorted to form a reactive shock bifurcation structure with detonations initiating at different three-dimensional spatial locations. Moreover, the detonation initiation would occur earlier in a mixture of more enhanced reactivity. The results reveal that the detona- tions arise from hot spots in the unburned region which are initiated by the shock-detonation-transition mechanism.
文摘Molecular structures of reactants were characterized by molecular electronegativity distance vector （VHMED） considering hydrogen association. A reasonable molecular modeling equation with 4-parameters was achieved for quantitative structure-property/activity relationship （QSPR/QSAR） by stepwise multiple regression （SMR） that the variable was introduced item by item in significant level order. A high correlation coefficient （R = 0.980） demonstrates that the model is able to well express a quantitative relation between stereoselectivity and the reactant structures as quantitative structure-reactivity/stereoselectivity relationship （QSRR/QSSR）. The multiple correlation coefficient （Rcv= 0.964） was tested through cross-validation with the leave-one-out （LOO） procedure. The above results show that the model possesses high estimation stability and good prediction ability between the amount of both cis and trans isomers in products and reactants.
基金supported by the National Science Foundation of China(Nos.21377076,91543203,21477070,21222701)Specialized Research Fund for the Doctoral Program of Higher Education of China(Nos.20121401110003,20131401110005)+1 种基金Project Supported by Shanxi Young Sanjin Scholarship of China,Program for the Outstanding Innovative Teams of Higher Learning Institutions of ShanxiResearch Project Supported by Shanxi Scholarship Council of China(No.2015-006)
文摘In light of the accelerated aging of the global population and the deterioration of the atmosphere pollution, we sought to clarify the potential mechanisms by which fine particulate matter（PM_（2.5）） can cause cognitive impairment and neurodegeneration through the alteration of mitochondrial structure and function. The results indicate that PM_（2.5） inhalation reduces ATP production by disrupting the aerobic tricarboxylic acid cycle and oxidative phosphorylation, thereby causing the hypophosphorylation of tau in the cortices of middle-aged mice. Furthermore, excessive reactive oxygen species generation was involved in the impairment. Interestingly, these alterations were partially reversed after exposure to PM_（2.5） ended. These findings clarify the mechanism involved in mitochondrial abnormality-related neuropathological dysfunction in response to atmospheric PM_（2.5） inhalation and provide an optimistic sight for alleviating the adverse health outcomes in polluted areas.
基金the start-up fund provided by the Engineering Science and Mechanics Department, College of Engineering, and Materials Research Institute at the Pennsylvania State University (215-37 1001 cc:H.Cheng)
文摘Transient electronics are an emerging class of electronics with the unique characteristic to completely dissolve within a programmed period of time. Since no harmful byproducts are released, these electronics can be used in the human body as a diagnostic tool, for instance, or they can be used as environmentally friendly alternatives to existing electronics which disintegrate when exposed to water. Thus, the most crucial aspect of transient electronics is their ability to disintegrate in a practical manner and a review of the literature on this topic is essential for understanding the current capabilities of transient electronics and areas of future research. In the past, only partial dissolution of transient electronics was possible, however, total dissolution has been achieved with a recent discovery that silicon nanomembrane undergoes hydrolysis. The use of single- and multi-layered structures has also been explored as a way to extend the lifetime of the electronics. Analytical models have been developed to study the dissolution of various functional materials as well as the devices constructed from this set of functional materials and these models prove to be useful in the design of the transient electronics.
文摘We have generated one possible active site structure of Oxyhemocyanin (Oxy-Hc) and two possible active site structures of Oxytyrosinase (Oxy-Ty) using the EHMO method. Oxy-Hc active site has a plane configuration, while Oxy-Ty has boat configuration. When there exist water molecules, two water molecules are connected with the Oxy-Ty active site weakly. Calculations for the reactions of Oxy-Hc and Oxy-Ty (the water-off) with phenol demonstrate that the former reaction is thermodynamically forbidden, while the latter Is realizable.
基金the financial support from the Wageningen UR“IPOP Customized Nutrition”programme financed by Wageningen UR,the Dutch Ministry of Economic Affairs,WIAS,Agrifirm Innovation Center,ORFFA Additives BV,Ajinomoto Eurolysine s.a.s and Stichting VICTAM BV.SSV acknowledgesthe support from the Universidad de Costa Rica
文摘Background： Toasting during the production of rapeseed meal（RSM） decreases ileal crude protein（CP） and amino acid（AA） digestibility. The mechanisms that determine the decrease in digestibility have not been fully elucidated. A high protein quality, low-denatured, RSM was produced and toasted up to 120 min, with samples taken every 20 min. The aim of this study was to characterize secondary structure and chemical changes of proteins and glucosinolates occurring during toasting of RSM and the effects on its in vitro CP digestibility.Results： The decrease in protein solubility and the increase of intermolecular β-sheets with increasing toasting time were indications of protein aggregation. The contents of NDF and ADIN increased with increasing toasting time.Contents of arginine, lysine and O-methylisourea reactive lysine（OMIU-RL） linearly decreased with increasing toasting time, with a larger decrease of OMIU-RL than lysine. First-order reactions calculated from the measured parameters show that glucosinolates were degraded faster than lysine, OMIU-RL and arginine and that physical changes to proteins seem to occur before chemical changes during toasting. Despite the drastic physical and chemical changes noticed on the proteins, the coefficient of in vitro CP digestibility ranged from 0.776 to 0.750 and there were no effects on the extent of protein hydrolysis after 120 min. In contrast, the rate of protein hydrolysis linearly decreased with increasing toasting time, which was largely correlated to the decrease in protein solubility, lysine and OMIU-RL observed. Rate of protein hydrolysis was more than 2-fold higher for the untoasted RSM compared to the 120 min toasted material.Conclusions： Increasing the toasting time for the production of RSM causes physical and chemical changes to the proteins that decrease the rate of protein hydrolysis. The observed decrease in the rate of protein hydrolysis could impact protein digestion and utilization.
基金Funded by the National Natural Science Foundation of China(Nos.61705204 and 51606158)the Laser Fusion Research Center Funds for Young Talents(No.LFRC-PD011)
文摘Based on an advanced technology, randomly-aligned subwavelength structures（SWSs） were obtained by a metal-nanodot-induced one-step self-masking reactive-ion-etching process on a fused silica surface. Metal-fluoride（mainly ferrous-fluoride） nanodots induce and gather stable fluorocarbon polymer etching inhibitors in the reactive-ion-etching polymers as masks. Metal fluoride（mainly ferrous fluoride） is produced by the sputtering of argon plasma and the ion-enhanced chemical reaction of metal atoms. With an increase in CHF_3/Ar gas flow ratio, the average height of the SWSs increases, the number of SWSs per specific area increases and then decreases, and the optical transmittance of visible light increases and then decreases. The optimum CHF_3/Ar gas flow ratio for preparing SWSs is 1：5.
基金Funded by the National Natural Science Foundation of China(51071178)the Natural Science Foundation of Hunan Province,China(12JJ4044)the State Science and Technology Support Program(2012BAC02B05)
文摘Porous Fe-Sialloys with different nominalcompositions ranging from Fe-10wt% Sito Fe-50wt% Siwere fabricated through a reactive synthesis of Fe and Sielementalpowder mixtures.The effects of Sicontents on the pore structure of porous Fe-Sialloy were investigated in detail.The results showed that the open porosity,gas permeability and maximum pore size of the porous Fe-Sialloys increased with increasing Sicontents,indicating that the porosity and pore size can be tailored by changing the Sicontents.The pore structure parameter including the open porosity,gas permeability,maximum pore size obeyed the HagenPoiseuille formula with the constant G=0.035 m^（-1_Pa^（-1）s^（-1） for the reactively synthesized porous Fe-Sialloys.The mechanicalproperty of the porous Fe-Sialloys showed applicability in the filtration industries.
基金supported by the National Natural Science Foundation of China(Nos.21266019,21062011 and 21462029)Inner Mongolia Autonomous Region Higher Scientific Research Project(NJZY14060)
文摘The reactivity of carbonyl iron cluster with alkynes has been studied by the thermal reaction of Fe_3（CO）_（12） with R-C≡C-R＇（R = Fc（Ferrocenyl）; R′ = Ph（Phenyl）, Fc, H）. The hexacarbonyldiiron cluster with ferracyclopentadiene ring（μ_2, η~4-C_4Ph_4）Fe_2（CO）_6（1） and one tetraphenyl substituted cyclopentadienone（Ph_4C_4CO）（2） were simultaneously obtained by the reaction of Fe_3（CO）_（12） with alkyne（Ph-C≡C-Ph）. Only one ferrole cluster（μ_2, η~4-C_4Fc_2H_2）Fe_2（CO）_6（3） was separated by using Fc-C≡C-H as alkyne. One tri-carbonyl iron complex（η~4-C_4Fc_4CO）Fe（CO）_3（4） and an unexpected new cyclic ketone compound 2,2,4,5-tetraferrocenylcyclopenta-4-en-1,3-di-one [Fc_4C_3（CO）_2]（5） were obtained by using Fc-C≡C-Fc as alkyne. A new complex（η4-2,4-diphenyl-3,5-diferrocenylcyclopenta-2,4-dien-1-one）-tricarbonyl iron（η~4-C_4Ph_2Fc_2CO）Fe（CO）_3（6） was synthesized by the reaction of Fe_3（CO）_（12） with Fc-C≡C-Ph. The structures of compounds 1~6 were determined by X-ray single-crystal diffraction and spectroscopic characterization. The crystal structures of two new compounds 5 and 6 were analyzed. Our experimental results reveal the structural models of the reaction products are affected by the kinds of substituents from alkynes R-C≡C-R′.
文摘Cerium-aluminum(CeAl)alloy is promising reactive structural materials(RSMs)with significant potential for liner applications.To investigate the thermochemical characteristics of CeAl alloy and the perforation behavior of its liner impacting steel targets,a CeAl alloy liner with 5 wt%Al content was fabricated,with a cerium(Ce)liner and a copper(Cu)liner used as control.The microstructure and elemental distribution of the CeAl alloy were analyzed using SEM,EDS,and XRD.The thermochemical reaction mechanism of the CeAl alloy was examined through TG-DSC.Penetration experiments were conducted to explore the combined effects of invasion and implosion of CeAl alloy liner against steel target.The results indicate that the addition of Al leads to the formation of Ce_(3)Al intermetallic compounds in the alloy and reduces the apparent activation energy of the Ce-based alloy by around 53.17%,thereby facilitating energy release.The presence of 5 wt%Al increases the calorific value by approximately 24.5%,and this change allows the oxidation process to be divided into three distinct stages.Compared to an inert copper liner,the average penetration diameter of the CeAl_(5) reactive alloy liner increases by around 42.78%.Furthermore,when compared to the Ce liner,the penetration depth of the CeAl_(5) reactive alloy liner increases by approximately 82.64%.
文摘Intraplate structural deformation is diagnostic of tectonic stress regime changes linked to plate interactions and can result from superposed tectonic events whose single contributions are hardly distinguishable.In this paper,we present a set of integrated thermochronologic inverse models along a 140 km-long transect across the central Greater Caucasus and the adjacent Adjara-Trialeti fold-and-thrust belt of Georgia,two intraplate orogens produced by structural inversion of parallel continental rift zones located on the Eurasian plate.Our dataset allows to distinguish discrete and superposed deformation episodes and quantify their respective contributions to orogenic exhumation.The integration of(U-Th)/He analysis on apatite and zircon,fission-track analysis on apatite,and peak-temperature determinations(clay mineralogy,organic matter petrography,Raman spectroscopy)shows that structural inversion was punctuated by two incremental steps starting respectively in the latest Cretaceous and the mid-Miocene.Latest Cretaceous partial inversion of the Greater Caucasus is documented here for the first time and placed in a geographically wider context of coeval deformation.The two episodes of intraplate structural inversion,exhumation,and sediment generation are chronologically and physically correlated with docking of(i)the Anatolide-Tauride-Armenian terrane(Late Cretaceous-Paleocene)and(ii)Arabia(Miocene hard collision)against the southern Eurasian plate margin.Intraplate deformation in the Caucasian domain was triggered by far-field propagation of plate-margin collisional stress which focused preferentially along rheologically weak rift zones.
文摘Drug innovation is characterized by painstaking molecular-level syntheses and modifications as the basic components of research and development.Similarly,natural products are chemically tailored and modified based upon their structural and biological properties.To some extent,the modification of natural products is quite different from de novo structure-based drug discovery.This review describes the general strategies and principles for the modification of natural products to drugs,as illustrated by several successful medicines that originated from natural products.
文摘The physiochemical properties of chars produced by coal pyrolysis in a laboratory-scale fluidized bed reactor with a continuous coal feed and char discharge at temperatures of 750 to 980 ~ C under N2-based atmospheres containing 02, H2, CO, CH4, and CO2 were studied. The specific surface area of the char was found to decrease with increasing pyrolysis temperature. The interlayer spacing of the char also decreased, while the average stacking height and carbon crystal size increased at higher temperatures, suggesting that the char generated at high temperatures had a highly ordered structure. The char obtained using an ER value of 0.064 exhibited the highest specific surface area and oxidation reactivity. Rela- tively high 02 concentrations degraded the pore structure of the char, decreasing the surface area. The char produced in an atmosphere incorporating H2 showed a more condensed crystalline structure and consequently had lower oxidation reactivity.
文摘With the support by the National Natural Science Foundation of China,a collaboration by the research groups led by Prof.Cheng Gang(程纲)from Henan University and Prof.Wang Zhonglin(王中林)from Beijing Institute of Nanoenergy and Nanosystems,Chinese Academy of Sciences,invents'a sliding-mode triboelectric nanogenerator with chemical group grated structure by shadow mask reactive ion etching',which was published in ACS Nano(2017,11(9):8796-8803).
基金provided by the National Natural Science Foundation of China(nos.21973052,21933008)the Young Elite Scientists Sponsorship Program by CAST(no.2019QNRC001),and the Haihe Laboratory of Sustainable Chemical Transformations.
文摘Electronic and bonding situations at reaction centers are often detected by the remote substituent effect.For nonorganometallic reactions,this effect is conventionally described by the well-known Hammett-type substituent constants.However,for most transition metal(TM)-involved systems,no analogous numeral descriptors reflecting the intrinsic differences between metallic and nonmetallic bonding have been rigorously established till present.Herein,we report a Pd(II)–O bond heterolysis energyΔG_(het)(Pd–O)study of the archetypal palladium complexes to represent the thermodynamics of the essential bond-breaking step in Pd-mediated transformations.Meanwhile we furnish the new substituent constantsσPd^(+)s and therefrom facilitate linear free-energy relationship(LFER)analysis for Pd-catalyzed reactions.Indeed,this led us to find an unexpected electron-donating ability of Pd(II)cation,which provided a gifted experimental support,with the aid of computation,to attribute the frustrating observation of a much scattered curvature in theΔG_(het)(Pd–O)-σ+correlation to the electrondonating capacity of the cationic palladium through back-donation of its d-electrons.Applications of LFER analysis withσPd^(+)to predict the redox behavior of the palladium complex and in a kinetics vs.thermodynamicsmechanistic study of transmetalation added further credence to their applicability to TM systems.
