[Objectives] To investigate the anti-tumor activity of Sedum bulbiferum Makino in vitro,and establish a HPLC method for determination of quercetin and kaempferol in S. bulbiferum. [Methods] The inhibitory activities o...[Objectives] To investigate the anti-tumor activity of Sedum bulbiferum Makino in vitro,and establish a HPLC method for determination of quercetin and kaempferol in S. bulbiferum. [Methods] The inhibitory activities of different extracts and total flavonoids of S. bulbiferum on proliferation of three kinds of cancer cells( Hep G2,EC109,SW480) were tested by MTT assay. HPLC method for determination of quercetin and kaempferol in S. bulbiferum was established. [Results]The growth and proliferation of the three kinds of cancer cells were all significantly inhibited by ethyl acetate fraction and total flavonoids isolated from S. bulbiferum. With each extraction concentration increasing,stronger anti-tumor activity was found. The linear ranges of quercetin and kaempferol were 0. 03-0. 36 μg( R = 0. 999 9) and0. 08-0. 96 μg( R = 0. 999 9),and the average recoveries were 98. 90%( RSD = 1. 15%) and 98. 27%( RSD = 1. 70%),respectively.[Conclusions]S. bulbiferum has significant anti-tumor activity in vitro. The HPLC method established was accurate,reproducible,and could be used for quality control of this crude drug.展开更多
With a growing awareness of pollution and increasing demands for environmental protection, a great deal of effort is being put into the development of catalysts with improved activity for the abatement of pollutants, ...With a growing awareness of pollution and increasing demands for environmental protection, a great deal of effort is being put into the development of catalysts with improved activity for the abatement of pollutants, which are mainly emitted by industrial plants and transport vehicles.展开更多
[Objectives] To establish methods of HPLC fingerprint and simultaneous determination of the three bioactive components(namely, asperosaponin VI, loganin and sweroside) of Dipsaci Radix, and explore the quality situati...[Objectives] To establish methods of HPLC fingerprint and simultaneous determination of the three bioactive components(namely, asperosaponin VI, loganin and sweroside) of Dipsaci Radix, and explore the quality situation of this crude medicine collected in various months in autumn. [Methods] The analysis was performed on Thermo BDS Hypersil C_(18)(4.6 mm×250 mm, 5 μm) column with a mixture of acetonitrile and 0.1% phosphoric acid as mobile phase in gradient mood at a flow rate of 1.0 mL/min, the column temperature was set at 30 ℃, and the detection wavelength was 220 nm. [Results] The analysis methods for HPLC fingerprint and determination of the three components in Dipsaci Radix had been established. The results showed that 12 batches of samples, which were collected in four different places from September to November, possessed the similarities of greater than 0.976. Through the quantitative analysis of asperosaponin VI, loganin and sweroside in Dipsaci Radix, it was found that the quality variation of this herbal medicine and the different collected months of autumn showed a low correlation. [Conclusions] The established methods of HPLC characteristic fingerprint and simultaneous determination of three glycosides provided a new way for quality analysis of Dipsaci Radix. It was preliminarily indicated that collecting this plant medicine in different months of autumn would not affect its quality.展开更多
International trade of textiles and clothing has numerous environmental implications, such as carbon leakage. In order to estimate the CO2 emissions embodied in China's imports and exports of textiles and clothing...International trade of textiles and clothing has numerous environmental implications, such as carbon leakage. In order to estimate the CO2 emissions embodied in China's imports and exports of textiles and clothing, an empirical analysis was carried out with environmental input-output analysis (EIOA) method using the most recent data available. The results indicate that China is a net exporter of embodied CO2 emissions on account of its international trade of textiles and clothing. The amount of the net exported embodied CO2 emissions increases from 110 million metric tons(Mt) of CO2 in 2002 to 280 Mt of CO2 in 2011. In particular, United States, Japan, and European Union transfer to China 339 Mt of CO2, 291 Mt of CO2 and 396 Mt of CO2 respectively during the period of 2002 -2011.展开更多
Phenylalanine (Phe) is a significant amino acid that cannot be synthesized by human themselves but must be taken from environment. It was initially found that the nanosized amorphous Ni-B/SiO2 alloy prepared by the ...Phenylalanine (Phe) is a significant amino acid that cannot be synthesized by human themselves but must be taken from environment. It was initially found that the nanosized amorphous Ni-B/SiO2 alloy prepared by the chemical reduction method was an effective catalyst for the preparation of Phe from phenylpyruvic acid (PPA) by amination and hydrogenation. It has been found that the amorphous Ni-B/SiO2 alloy catalyst exhibits superior activity and selectivity to the traditional catalysts Raney Ni and Urushibara nickel. The effects of reaction time, amounts of catalysts and ammonia solution, reaction temperature, and H2 pressure on the reaction have been investigated systematically. The results indicated that the yield of Phe was 97.9%, and the selectivity for Phe reached 98.9% when the reaction was carried out for 3 h at 333 K and 2.0 MPa of H2 with m(Cat.) : m(PPA) = 0.6 : 1.0 and n(NH3) : n(PPA) = 3 : 1. The catalysts were characterized by XRD, AAS, XPS, BET, and TEM, and the relationship between the catalyst structure and the catalytic activity was discussed in detail. It was found that the reason why Ni-B/SiO2 amorphous alloy catalyst was much more active for the preparation of Phe could be accounted for by the presence of electron-rich Ni due to electron donation from alloying B; the smaller size of Ni-B particles, the larger specific surface area of Ni-B/SiO2.展开更多
A new alkylpyrrole derivative,fusariumin A(1),was isolated from the culture broth of the fungus Fusarium sp.The absolute configuration of fuasiumin A has been established as(2'R,3'R)using a combination of RDC(...A new alkylpyrrole derivative,fusariumin A(1),was isolated from the culture broth of the fungus Fusarium sp.The absolute configuration of fuasiumin A has been established as(2'R,3'R)using a combination of RDC(residual dipolar coupling)-based NMR and DFT-supported chiroptical spectroscopy.It is worth to note that in this study without the aid of the RDC analysis,an unambiguous determination of configuration and conformation was not feasible due to the excessive conformational possibilities of this open-chain compound.展开更多
To unify the four known fundamental forces and provide an explanation for the origin and the evolution of the universe are two long-term goals of theoretical physics. Here a “universe collapse model” has been propos...To unify the four known fundamental forces and provide an explanation for the origin and the evolution of the universe are two long-term goals of theoretical physics. Here a “universe collapse model” has been proposed. The universe consists of Matter and No-matter. No-matter is the universal energy that constructs a consistent universe field, presenting a spiral wave motion at the speed of light at the small scale. The partial collapse of the universal energy forms the particles of the universal energy in a variety of sizes, which are called as the elementary particles. These elementary particles form atom and matter, which construct the galaxies. The collapse of the universe field induces the formation of the universe collapse potential (UCP) and universe collapse force (UCF), and the later is represented by four different aspects of the fundamental forces at the large or small scales. The mathematical equation and the derivation of UCP and UCF are described, and possible experimental tests are also suggested. Therefore, this new model may give a novel explanation for the unification of four fundamental forces and the origin and the evolution of the universe.展开更多
A long-term goal of theoretical physics is to develop a single simple theory or model that would unify the four known fundamental forces (or interactions) and give explanations for the origin and the evolution of the ...A long-term goal of theoretical physics is to develop a single simple theory or model that would unify the four known fundamental forces (or interactions) and give explanations for the origin and the evolution of the Universe. Here a “spiral wave law” has been proposed based on the previous studies that a consistent universe field presents various forms of spiral (helical) wave motions at the speed of light (c), and therefore, a mathematical equation for the relationship between the radius of a spiral wave motion (r) and its wave length (λ) is derived including a simplified formula ( or ), which could provide a novel explanation for the origin and the evolution of the Universe, and the space-time relationships. This model may give a new way for the unification of four fundamental forces and determine the moving properties of galaxies and basic particles, and the propagation characteristics of electromagnetic waves at the large or small scale.展开更多
Brownian motion was discovered by the botanist Robert Brown in 1827, and the theoretical model of Brownian motion has real-world applications in fields such as mathematics, economics, physics and biology. It is the pr...Brownian motion was discovered by the botanist Robert Brown in 1827, and the theoretical model of Brownian motion has real-world applications in fields such as mathematics, economics, physics and biology. It is the presumably random motion of particles suspended in a liquid or a gas that results from their bombardment by fast-moving atoms or molecules, but the exact mechanism of Brownian motion still remains one of the unresolved mysteries in physics. Here circadian and seasonal changes in long-term macroscopic anisotropic (asymmetric) Brownian motion of a toluidine blue colloid solution in water in two dimensions were identified, suggesting that such an anisotropic Brownian motion may be related to an effect of the directional movement of “Universe field”, and thereby providing new interpretations and potential applications of Brownian motion.展开更多
With the development of the mobile communication technology,a wide variety of envisioned intelligent transportation systems have emerged and put forward more stringent requirements for vehicular communications.Most of...With the development of the mobile communication technology,a wide variety of envisioned intelligent transportation systems have emerged and put forward more stringent requirements for vehicular communications.Most of computation-intensive and power-hungry applications result in a large amount of energy consumption and computation costs,which bring great challenges to the on-board system.It is necessary to exploit traffic offloading and scheduling in vehicular networks to ensure the Quality of Experience(QoE).In this paper,a joint offloading strategy based on quantum particle swarm optimization for the Mobile Edge Computing(MEC)enabled vehicular networks is presented.To minimize the delay cost and energy consumption,a task execution optimization model is formulated to assign the task to the available service nodes,which includes the service vehicles and the nearby Road Side Units(RSUs).For the task offloading process via Vehicle to Vehicle(V2V)communication,a vehicle selection algorithm is introduced to obtain an optimal offloading decision sequence.Next,an improved quantum particle swarm optimization algorithm for joint offloading is proposed to optimize the task delay and energy consumption.To maintain the diversity of the population,the crossover operator is introduced to exchange information among individuals.Besides,the crossover probability is defined to improve the search ability and convergence speed of the algorithm.Meanwhile,an adaptive shrinkage expansion factor is designed to improve the local search accuracy in the later iterations.Simulation results show that the proposed joint offloading strategy can effectively reduce the system overhead and the task completion delay under different system parameters.展开更多
Nuciferine contained in lotus leaves have been confirmed to have the effect of ameliorating hyperlipemia and hyperglycemia.A laser scanning confocal microscope was used to track the translocation of glucose transporte...Nuciferine contained in lotus leaves have been confirmed to have the effect of ameliorating hyperlipemia and hyperglycemia.A laser scanning confocal microscope was used to track the translocation of glucose transporter 4(GLUT4)in L6 cells and the changes in intracellular Ca^(2+)levels in real time,and related protease inhibitors combined with western blotting were used to explore the mechanism of nuciferine.Meanwhile,KK-Ay mice,the spontaneous type 2 diabetic mice,were used to evaluate the in vivo activity of nuciferine.In this study,the in vitro studies indicated that nuciferine-induced GLUT4 translocation was regulated by G protein-PLC-PKC and AMPK pathways and nuciferine-enhanced intracellular Ca^(2+)was mediated by G protein-PLC-IP3-IP3R pathway,the increase in intracellular Ca^(2+)caused by nuciferine was not directly related to GLUT4 translocation,but both promote glucose uptake.The in vivo results suggested that nuciferine ameliorated weight gain induced by high-fat diet,abnormal lipid metabolism and the symptoms of insulin resistance in KK-Ay diabetic mice.Western blot results suggested that nuciferine increased AMPK and PKC phosphorylation levels in skeletal muscle and liver,and enhanced GLUT4 expression in skeletal muscle.Taken together,this research showed that nuciferine has the non-negligible potential in the treatment of type 2 diabetes mellitus.展开更多
Lithium metal has been considered one of the most promising anodes for next-generation rechargeable batteries,but its practical application is largely hindered by the uncontrollable dendrite growth and infinite volume...Lithium metal has been considered one of the most promising anodes for next-generation rechargeable batteries,but its practical application is largely hindered by the uncontrollable dendrite growth and infinite volume change.Here,inspired by superior catalytic effects of single-atom catalysts,carbon-supported single atomic Co with asymmetric N,O-coordination(Co-N/O)is developed for Li metal battery.Experimental results and theoretical calculations indicate that single atomic Co atoms with asymmetric N,O-coordination present enhanced binding ability toward Li in comparison with N-coordinated atomic Co site and isolated O site,enabling uniform Li plating/stripping.Moreover,the asymmetric N,O-coordination around Co atoms induces co-activation effects,lowering the energy barriers toward Li^(+)to Li^(0)conversion and largely promoting the deposition kinetics.When used as a Li deposition host,the Co-N/O achieves a high average coulombic efficiency of 98.6%at a current density of 1 mA cm^(-2)and a capacity of 2 mAh cm^(-2),long cycling life of 2000 h in symmetrical cells,and excellent rate performance(voltage hysteresis of 23 mV at 8 mA cm^(-2)).This work provides a comprehensive understanding of single atomic metals with asymmetric heteroatom coordination in the design of Li metal anode.展开更多
In this work,a dual-size MOF-derived Co catalyst(0.2Co_(1-NPs)@NC)composed of single atoms(Co_(1))and highly dispersed nanoparticles(Co NPs)was prepared by in-situ Zn evaporation for the highperformance conversion of ...In this work,a dual-size MOF-derived Co catalyst(0.2Co_(1-NPs)@NC)composed of single atoms(Co_(1))and highly dispersed nanoparticles(Co NPs)was prepared by in-situ Zn evaporation for the highperformance conversion of lignin-derived o-methoxyphenols(lignin oil)to cyclohexanols(up to 97%yield)via cascade demethoxylation and dearomatization.Theoretical calculations elaborated that the dual-size Co catalyst exhibited a cooperative effect in the selective demethoxylation process,in which the Co NPs could initially dissociate hydrogen at lower energies while Co1remarkably facilitated the cleavage of the C_(Ar)-OCH_(3)bond.Moreover,the intramolecular hydrogen bonds formed in the omethoxy-containing phenols were found to result in a decrease in the bond energy of the C_(Ar)-OCH_(3)bond,which was more prone to be activated by the dual-size Co sites.Notably,the pre-hydrogenated intermediate(e.g.,2-methoxycyclohexanol from guaiacol)is difficult to undergo demethoxylation,indicating that the selective C_(Ar)-OCH_(3)bond cleavage is a prerequisite for the synthesis of cyclohexanols.The 0.2Co_(1-NPs)@NC catalyst was highly recyclable with a neglect decline in activity during five consecutive cycles.This cooperative catalytic strategy based on the metal size effect opens new avenues for biomass upgrading via enhanced C-O bond cleavage of high selectivity.展开更多
Li metal anode holds great promise to realize high-energy battery systems.However,the safety issue and limited lifetime caused by the uncontrollable growth of Li dendrites hinder its commercial application.Herein,an i...Li metal anode holds great promise to realize high-energy battery systems.However,the safety issue and limited lifetime caused by the uncontrollable growth of Li dendrites hinder its commercial application.Herein,an interlayer-bridged 3D lithiophilic rGO-Ag-S-CNT composite is proposed to guide uniform and stable Li plating/stripping.The 3D lithiophilic rGO-Ag-S-CNT host is fabricated by incorporating Ag-modified reduced graphene oxide(rGO)with S-doped carbon nanotube(CNT),where the rGO and CNT are closely connected via robust Ag-S covalent bond.This strong Ag-S bond could enhance the structural stability and electrical connection between rGO and CNT,significantly improving the electrochemical kinetics and uniformity of current distribution.Moreover,density functional theory calculation indicates that the introduction of Ag-S bond could further boost the binding energy between Ag and Li,which promotes homogeneous Li nucleation and growth.Consequently,the rGO-Ag-S-CNT-based anode achieves a lower overpotential(7.3 mV at 0.5 mA cm^(−2)),higher Coulombic efficiency(98.1%at 0.5 mA cm^(−2)),and superior long cycling performance(over 500 cycles at 2 mA cm−2)as compared with the rGO-Ag-CNT-and rGO-CNT-based anodes.This work provides a universal avenue and guidance to build a robust Li metal host via constructing a strong covalent bond,effectively suppressing the Li dendrites growth to prompt the development of Li metal battery.展开更多
Rechargeable Mg batteries(RMBs)are a promising large-scale energy-storage technology with low cost and high safety,but the performance is limited by the inferior kinetics of Mg-intercalation cathodes.In the present st...Rechargeable Mg batteries(RMBs)are a promising large-scale energy-storage technology with low cost and high safety,but the performance is limited by the inferior kinetics of Mg-intercalation cathodes.In the present study,an octylamine-supporting interlayer expanded molybdenum diselenide(e-MoSe_(2))is synthesized and used as cathode for RMBs,in comparison with ordinary crystalline MoSe_(2).The octylamine molecules introduced show a strong interaction with the MoSe_(2)layers and increase the layer spacing significantly from 6.46 to 11.5Å.e-MoSe_(2)shows a high Mg-storage capacity of 238 mAh g^(-1)at 50 mA g^(-1)and a superior rate performance of 39 mAh g^(-1)at 10 A g1,far advantageous over crystalline MoSe_(2).e-MoSe_(2)also shows a considerably high structure stability during repeated magnesiation/demagnesiation,providing an outstanding cycling stability for 1000 cycles.Further electrochemical tests demonstrate the high Mg^(2+)diffusion coefficients in e-MoSe_(2).Theoretical computation indicates the interlayer expansion changes the Mg^(2+)diffusion paths from"hollow site→hollow site"to"hollow site→Se atom site→hollow site",largely decreasing the energy barrier and improving the Mg^(2+)diffusion kinetics.The present work highlights an efficient strategy for the improvement of Mg-storage performance for RMB cathodes.展开更多
Academic journals are vital for the dissemination of sci-entific knowledge,the encouragement of scholarly dis-cussions,and the advancement of research across vari-ous disciplines.The impact of a journal,measured by it...Academic journals are vital for the dissemination of sci-entific knowledge,the encouragement of scholarly dis-cussions,and the advancement of research across vari-ous disciplines.The impact of a journal,measured by its influence on academic and professional communities,is a key indicator of its success.In the latest Journal Citation Report(JCR)released by Clarivate in June 2023,Natural Products and Bioprospecting(NPB)got the first impact factor of 4.7.This is another milestone in the journal’s efforts to expand its academic influence.Natural Prod-ucts and Bioprospecting is currently indexed by several prominent databases,including the Emerging Sources Citation Index(ESCI),the Directory of Open Access Journals(DOAJ),PubMed Central,and Scopus.The 2022 Citescore of the journal is 7.5,ranking at Q1 of Plant Sci-ence and Food Science,Q2 of Analytical Chemistry,Bio-chemistry,Organic Chemistry,Pharmacology,and Toxi-cology.The journal has a yearly downloads of more than 326k,and a yearly Altmetric mentions of over 350.展开更多
Herein,we disclose a novel copper-catalyzed C(sp)-H aryl amination of terminal alkynes with anthranils,enabling the rapid generation of highly reactive secondary N-aryl ynamines for the modular synthesis of structural...Herein,we disclose a novel copper-catalyzed C(sp)-H aryl amination of terminal alkynes with anthranils,enabling the rapid generation of highly reactive secondary N-aryl ynamines for the modular synthesis of structurally diverse C2-substituted quinolines and 2-quinolinones.The in-situ formed carbonyl-ynamines are prone to tautomerize to carbonyl-ketenimines,which can efficiently react with a series of nucleophiles,including amines,alcohols,phenols,thiols,thiophenols,active-methylene compounds,and even water to produce various quinoline derivatives with the generation of H_(2)O as a sole and green byproduct.This method also unlocks a practical route to create various quinoline-fused heterocycles and can be successfully applied to the late-stage modification of complex molecules and the concise synthesis of bioactive targets.Mechanistic studies reveal a coppercatalyzed inner-sphere nitrene transfer process by using anthranils as novel aryl nitrene precursors.展开更多
Concise assembly of spirooxindoles is of great significance but a challenging task in modern organic synthesis.Described herein is an unusual base-promoted[4+2]spiroannulation of rarely used isatin-derivedβ-silylcarb...Concise assembly of spirooxindoles is of great significance but a challenging task in modern organic synthesis.Described herein is an unusual base-promoted[4+2]spiroannulation of rarely used isatin-derivedβ-silylcarbinols with o-halogen aromatic ketones,which enables rapid and modular synthesis of six-membered carbocyclic spirooxindoles in high yields with excellent functional group tolerance(>50 examples).Mechanistic experiments revealed that this reaction involved a Peterson olefination,Michael addition and intramolecular C(sp^(3))arylation cascade.The variegated synthetic derivatization of target products and successful construction of bioactive molecules further illustrate the synthetic potential in spirooxindole-related drug discovery.展开更多
文摘[Objectives] To investigate the anti-tumor activity of Sedum bulbiferum Makino in vitro,and establish a HPLC method for determination of quercetin and kaempferol in S. bulbiferum. [Methods] The inhibitory activities of different extracts and total flavonoids of S. bulbiferum on proliferation of three kinds of cancer cells( Hep G2,EC109,SW480) were tested by MTT assay. HPLC method for determination of quercetin and kaempferol in S. bulbiferum was established. [Results]The growth and proliferation of the three kinds of cancer cells were all significantly inhibited by ethyl acetate fraction and total flavonoids isolated from S. bulbiferum. With each extraction concentration increasing,stronger anti-tumor activity was found. The linear ranges of quercetin and kaempferol were 0. 03-0. 36 μg( R = 0. 999 9) and0. 08-0. 96 μg( R = 0. 999 9),and the average recoveries were 98. 90%( RSD = 1. 15%) and 98. 27%( RSD = 1. 70%),respectively.[Conclusions]S. bulbiferum has significant anti-tumor activity in vitro. The HPLC method established was accurate,reproducible,and could be used for quality control of this crude drug.
文摘With a growing awareness of pollution and increasing demands for environmental protection, a great deal of effort is being put into the development of catalysts with improved activity for the abatement of pollutants, which are mainly emitted by industrial plants and transport vehicles.
基金Supported by the Natural Science Foundation of China(31470406)
文摘[Objectives] To establish methods of HPLC fingerprint and simultaneous determination of the three bioactive components(namely, asperosaponin VI, loganin and sweroside) of Dipsaci Radix, and explore the quality situation of this crude medicine collected in various months in autumn. [Methods] The analysis was performed on Thermo BDS Hypersil C_(18)(4.6 mm×250 mm, 5 μm) column with a mixture of acetonitrile and 0.1% phosphoric acid as mobile phase in gradient mood at a flow rate of 1.0 mL/min, the column temperature was set at 30 ℃, and the detection wavelength was 220 nm. [Results] The analysis methods for HPLC fingerprint and determination of the three components in Dipsaci Radix had been established. The results showed that 12 batches of samples, which were collected in four different places from September to November, possessed the similarities of greater than 0.976. Through the quantitative analysis of asperosaponin VI, loganin and sweroside in Dipsaci Radix, it was found that the quality variation of this herbal medicine and the different collected months of autumn showed a low correlation. [Conclusions] The established methods of HPLC characteristic fingerprint and simultaneous determination of three glycosides provided a new way for quality analysis of Dipsaci Radix. It was preliminarily indicated that collecting this plant medicine in different months of autumn would not affect its quality.
基金Special Fund for Quality Inspection Research in the Public Interest,the Ministry of Science and Technology,China(No.201010041)the Fundamental Research Funds for the Central Universities,China
文摘International trade of textiles and clothing has numerous environmental implications, such as carbon leakage. In order to estimate the CO2 emissions embodied in China's imports and exports of textiles and clothing, an empirical analysis was carried out with environmental input-output analysis (EIOA) method using the most recent data available. The results indicate that China is a net exporter of embodied CO2 emissions on account of its international trade of textiles and clothing. The amount of the net exported embodied CO2 emissions increases from 110 million metric tons(Mt) of CO2 in 2002 to 280 Mt of CO2 in 2011. In particular, United States, Japan, and European Union transfer to China 339 Mt of CO2, 291 Mt of CO2 and 396 Mt of CO2 respectively during the period of 2002 -2011.
基金Fundamental research project of South-Central University for Nationalities (No. YZZ05010)
文摘Phenylalanine (Phe) is a significant amino acid that cannot be synthesized by human themselves but must be taken from environment. It was initially found that the nanosized amorphous Ni-B/SiO2 alloy prepared by the chemical reduction method was an effective catalyst for the preparation of Phe from phenylpyruvic acid (PPA) by amination and hydrogenation. It has been found that the amorphous Ni-B/SiO2 alloy catalyst exhibits superior activity and selectivity to the traditional catalysts Raney Ni and Urushibara nickel. The effects of reaction time, amounts of catalysts and ammonia solution, reaction temperature, and H2 pressure on the reaction have been investigated systematically. The results indicated that the yield of Phe was 97.9%, and the selectivity for Phe reached 98.9% when the reaction was carried out for 3 h at 333 K and 2.0 MPa of H2 with m(Cat.) : m(PPA) = 0.6 : 1.0 and n(NH3) : n(PPA) = 3 : 1. The catalysts were characterized by XRD, AAS, XPS, BET, and TEM, and the relationship between the catalyst structure and the catalytic activity was discussed in detail. It was found that the reason why Ni-B/SiO2 amorphous alloy catalyst was much more active for the preparation of Phe could be accounted for by the presence of electron-rich Ni due to electron donation from alloying B; the smaller size of Ni-B particles, the larger specific surface area of Ni-B/SiO2.
基金Support by the National Natural Science Foundation of China(U1132607)to J.K.L.the DFG(Forschergruppe FOR 934)to C.Gas well as the Chinese/German foundation(GZ1104)to H.S.and C.G.is acknowledged.
文摘A new alkylpyrrole derivative,fusariumin A(1),was isolated from the culture broth of the fungus Fusarium sp.The absolute configuration of fuasiumin A has been established as(2'R,3'R)using a combination of RDC(residual dipolar coupling)-based NMR and DFT-supported chiroptical spectroscopy.It is worth to note that in this study without the aid of the RDC analysis,an unambiguous determination of configuration and conformation was not feasible due to the excessive conformational possibilities of this open-chain compound.
文摘To unify the four known fundamental forces and provide an explanation for the origin and the evolution of the universe are two long-term goals of theoretical physics. Here a “universe collapse model” has been proposed. The universe consists of Matter and No-matter. No-matter is the universal energy that constructs a consistent universe field, presenting a spiral wave motion at the speed of light at the small scale. The partial collapse of the universal energy forms the particles of the universal energy in a variety of sizes, which are called as the elementary particles. These elementary particles form atom and matter, which construct the galaxies. The collapse of the universe field induces the formation of the universe collapse potential (UCP) and universe collapse force (UCF), and the later is represented by four different aspects of the fundamental forces at the large or small scales. The mathematical equation and the derivation of UCP and UCF are described, and possible experimental tests are also suggested. Therefore, this new model may give a novel explanation for the unification of four fundamental forces and the origin and the evolution of the universe.
文摘A long-term goal of theoretical physics is to develop a single simple theory or model that would unify the four known fundamental forces (or interactions) and give explanations for the origin and the evolution of the Universe. Here a “spiral wave law” has been proposed based on the previous studies that a consistent universe field presents various forms of spiral (helical) wave motions at the speed of light (c), and therefore, a mathematical equation for the relationship between the radius of a spiral wave motion (r) and its wave length (λ) is derived including a simplified formula ( or ), which could provide a novel explanation for the origin and the evolution of the Universe, and the space-time relationships. This model may give a new way for the unification of four fundamental forces and determine the moving properties of galaxies and basic particles, and the propagation characteristics of electromagnetic waves at the large or small scale.
文摘Brownian motion was discovered by the botanist Robert Brown in 1827, and the theoretical model of Brownian motion has real-world applications in fields such as mathematics, economics, physics and biology. It is the presumably random motion of particles suspended in a liquid or a gas that results from their bombardment by fast-moving atoms or molecules, but the exact mechanism of Brownian motion still remains one of the unresolved mysteries in physics. Here circadian and seasonal changes in long-term macroscopic anisotropic (asymmetric) Brownian motion of a toluidine blue colloid solution in water in two dimensions were identified, suggesting that such an anisotropic Brownian motion may be related to an effect of the directional movement of “Universe field”, and thereby providing new interpretations and potential applications of Brownian motion.
基金funded by National Natural Science Foundation of China (Grant number 62076106).
文摘With the development of the mobile communication technology,a wide variety of envisioned intelligent transportation systems have emerged and put forward more stringent requirements for vehicular communications.Most of computation-intensive and power-hungry applications result in a large amount of energy consumption and computation costs,which bring great challenges to the on-board system.It is necessary to exploit traffic offloading and scheduling in vehicular networks to ensure the Quality of Experience(QoE).In this paper,a joint offloading strategy based on quantum particle swarm optimization for the Mobile Edge Computing(MEC)enabled vehicular networks is presented.To minimize the delay cost and energy consumption,a task execution optimization model is formulated to assign the task to the available service nodes,which includes the service vehicles and the nearby Road Side Units(RSUs).For the task offloading process via Vehicle to Vehicle(V2V)communication,a vehicle selection algorithm is introduced to obtain an optimal offloading decision sequence.Next,an improved quantum particle swarm optimization algorithm for joint offloading is proposed to optimize the task delay and energy consumption.To maintain the diversity of the population,the crossover operator is introduced to exchange information among individuals.Besides,the crossover probability is defined to improve the search ability and convergence speed of the algorithm.Meanwhile,an adaptive shrinkage expansion factor is designed to improve the local search accuracy in the later iterations.Simulation results show that the proposed joint offloading strategy can effectively reduce the system overhead and the task completion delay under different system parameters.
基金financially supported by National Natural Science Foundation of China grants(81573561,81911540487,31070744)the Fundamental Research Funds for the Central Universities,South-Central University for Nationalities(CZR18003).
文摘Nuciferine contained in lotus leaves have been confirmed to have the effect of ameliorating hyperlipemia and hyperglycemia.A laser scanning confocal microscope was used to track the translocation of glucose transporter 4(GLUT4)in L6 cells and the changes in intracellular Ca^(2+)levels in real time,and related protease inhibitors combined with western blotting were used to explore the mechanism of nuciferine.Meanwhile,KK-Ay mice,the spontaneous type 2 diabetic mice,were used to evaluate the in vivo activity of nuciferine.In this study,the in vitro studies indicated that nuciferine-induced GLUT4 translocation was regulated by G protein-PLC-PKC and AMPK pathways and nuciferine-enhanced intracellular Ca^(2+)was mediated by G protein-PLC-IP3-IP3R pathway,the increase in intracellular Ca^(2+)caused by nuciferine was not directly related to GLUT4 translocation,but both promote glucose uptake.The in vivo results suggested that nuciferine ameliorated weight gain induced by high-fat diet,abnormal lipid metabolism and the symptoms of insulin resistance in KK-Ay diabetic mice.Western blot results suggested that nuciferine increased AMPK and PKC phosphorylation levels in skeletal muscle and liver,and enhanced GLUT4 expression in skeletal muscle.Taken together,this research showed that nuciferine has the non-negligible potential in the treatment of type 2 diabetes mellitus.
基金supported by the Ministry of Education,Singapore,under its MOE tier2 grant MOE2019-T2-1-181.
文摘Lithium metal has been considered one of the most promising anodes for next-generation rechargeable batteries,but its practical application is largely hindered by the uncontrollable dendrite growth and infinite volume change.Here,inspired by superior catalytic effects of single-atom catalysts,carbon-supported single atomic Co with asymmetric N,O-coordination(Co-N/O)is developed for Li metal battery.Experimental results and theoretical calculations indicate that single atomic Co atoms with asymmetric N,O-coordination present enhanced binding ability toward Li in comparison with N-coordinated atomic Co site and isolated O site,enabling uniform Li plating/stripping.Moreover,the asymmetric N,O-coordination around Co atoms induces co-activation effects,lowering the energy barriers toward Li^(+)to Li^(0)conversion and largely promoting the deposition kinetics.When used as a Li deposition host,the Co-N/O achieves a high average coulombic efficiency of 98.6%at a current density of 1 mA cm^(-2)and a capacity of 2 mAh cm^(-2),long cycling life of 2000 h in symmetrical cells,and excellent rate performance(voltage hysteresis of 23 mV at 8 mA cm^(-2)).This work provides a comprehensive understanding of single atomic metals with asymmetric heteroatom coordination in the design of Li metal anode.
基金the Guizhou Provincial S&T Project(ZK[2022]011)the National Natural Science Foundation of China(21908033,21922513)+1 种基金the Natural Science Foundation of Guangxi Zhuang Autonomous Region(2020GXNSFAA297072)the Fok Ying-Tong Education Foundation(161030)。
文摘In this work,a dual-size MOF-derived Co catalyst(0.2Co_(1-NPs)@NC)composed of single atoms(Co_(1))and highly dispersed nanoparticles(Co NPs)was prepared by in-situ Zn evaporation for the highperformance conversion of lignin-derived o-methoxyphenols(lignin oil)to cyclohexanols(up to 97%yield)via cascade demethoxylation and dearomatization.Theoretical calculations elaborated that the dual-size Co catalyst exhibited a cooperative effect in the selective demethoxylation process,in which the Co NPs could initially dissociate hydrogen at lower energies while Co1remarkably facilitated the cleavage of the C_(Ar)-OCH_(3)bond.Moreover,the intramolecular hydrogen bonds formed in the omethoxy-containing phenols were found to result in a decrease in the bond energy of the C_(Ar)-OCH_(3)bond,which was more prone to be activated by the dual-size Co sites.Notably,the pre-hydrogenated intermediate(e.g.,2-methoxycyclohexanol from guaiacol)is difficult to undergo demethoxylation,indicating that the selective C_(Ar)-OCH_(3)bond cleavage is a prerequisite for the synthesis of cyclohexanols.The 0.2Co_(1-NPs)@NC catalyst was highly recyclable with a neglect decline in activity during five consecutive cycles.This cooperative catalytic strategy based on the metal size effect opens new avenues for biomass upgrading via enhanced C-O bond cleavage of high selectivity.
基金This work is supported by Singapore Ministry of Education academic research grant Tier 2 (MOE2019-T2-1-181).
文摘Li metal anode holds great promise to realize high-energy battery systems.However,the safety issue and limited lifetime caused by the uncontrollable growth of Li dendrites hinder its commercial application.Herein,an interlayer-bridged 3D lithiophilic rGO-Ag-S-CNT composite is proposed to guide uniform and stable Li plating/stripping.The 3D lithiophilic rGO-Ag-S-CNT host is fabricated by incorporating Ag-modified reduced graphene oxide(rGO)with S-doped carbon nanotube(CNT),where the rGO and CNT are closely connected via robust Ag-S covalent bond.This strong Ag-S bond could enhance the structural stability and electrical connection between rGO and CNT,significantly improving the electrochemical kinetics and uniformity of current distribution.Moreover,density functional theory calculation indicates that the introduction of Ag-S bond could further boost the binding energy between Ag and Li,which promotes homogeneous Li nucleation and growth.Consequently,the rGO-Ag-S-CNT-based anode achieves a lower overpotential(7.3 mV at 0.5 mA cm^(−2)),higher Coulombic efficiency(98.1%at 0.5 mA cm^(−2)),and superior long cycling performance(over 500 cycles at 2 mA cm−2)as compared with the rGO-Ag-CNT-and rGO-CNT-based anodes.This work provides a universal avenue and guidance to build a robust Li metal host via constructing a strong covalent bond,effectively suppressing the Li dendrites growth to prompt the development of Li metal battery.
基金supported by Intergovernmental International Science and Technology Innovation Cooperation Project(2019YFE0100200)National Natural Science Foundation of China(22179101 and 52172266).
文摘Rechargeable Mg batteries(RMBs)are a promising large-scale energy-storage technology with low cost and high safety,but the performance is limited by the inferior kinetics of Mg-intercalation cathodes.In the present study,an octylamine-supporting interlayer expanded molybdenum diselenide(e-MoSe_(2))is synthesized and used as cathode for RMBs,in comparison with ordinary crystalline MoSe_(2).The octylamine molecules introduced show a strong interaction with the MoSe_(2)layers and increase the layer spacing significantly from 6.46 to 11.5Å.e-MoSe_(2)shows a high Mg-storage capacity of 238 mAh g^(-1)at 50 mA g^(-1)and a superior rate performance of 39 mAh g^(-1)at 10 A g1,far advantageous over crystalline MoSe_(2).e-MoSe_(2)also shows a considerably high structure stability during repeated magnesiation/demagnesiation,providing an outstanding cycling stability for 1000 cycles.Further electrochemical tests demonstrate the high Mg^(2+)diffusion coefficients in e-MoSe_(2).Theoretical computation indicates the interlayer expansion changes the Mg^(2+)diffusion paths from"hollow site→hollow site"to"hollow site→Se atom site→hollow site",largely decreasing the energy barrier and improving the Mg^(2+)diffusion kinetics.The present work highlights an efficient strategy for the improvement of Mg-storage performance for RMB cathodes.
文摘Academic journals are vital for the dissemination of sci-entific knowledge,the encouragement of scholarly dis-cussions,and the advancement of research across vari-ous disciplines.The impact of a journal,measured by its influence on academic and professional communities,is a key indicator of its success.In the latest Journal Citation Report(JCR)released by Clarivate in June 2023,Natural Products and Bioprospecting(NPB)got the first impact factor of 4.7.This is another milestone in the journal’s efforts to expand its academic influence.Natural Prod-ucts and Bioprospecting is currently indexed by several prominent databases,including the Emerging Sources Citation Index(ESCI),the Directory of Open Access Journals(DOAJ),PubMed Central,and Scopus.The 2022 Citescore of the journal is 7.5,ranking at Q1 of Plant Sci-ence and Food Science,Q2 of Analytical Chemistry,Bio-chemistry,Organic Chemistry,Pharmacology,and Toxi-cology.The journal has a yearly downloads of more than 326k,and a yearly Altmetric mentions of over 350.
基金supported by the National Natural Science Foundation of China (22271065,22271314)the Guangzhou Basic and Applied Research (202201010396)。
文摘Herein,we disclose a novel copper-catalyzed C(sp)-H aryl amination of terminal alkynes with anthranils,enabling the rapid generation of highly reactive secondary N-aryl ynamines for the modular synthesis of structurally diverse C2-substituted quinolines and 2-quinolinones.The in-situ formed carbonyl-ynamines are prone to tautomerize to carbonyl-ketenimines,which can efficiently react with a series of nucleophiles,including amines,alcohols,phenols,thiols,thiophenols,active-methylene compounds,and even water to produce various quinoline derivatives with the generation of H_(2)O as a sole and green byproduct.This method also unlocks a practical route to create various quinoline-fused heterocycles and can be successfully applied to the late-stage modification of complex molecules and the concise synthesis of bioactive targets.Mechanistic studies reveal a coppercatalyzed inner-sphere nitrene transfer process by using anthranils as novel aryl nitrene precursors.
基金financial support of National Natural Science Foundation of China(21901193,22271314 and 22377097)the innovation foundation of Key Laboratory of Green Chemical Engineering Process of Ministry of Education(GCX2023002).
文摘Concise assembly of spirooxindoles is of great significance but a challenging task in modern organic synthesis.Described herein is an unusual base-promoted[4+2]spiroannulation of rarely used isatin-derivedβ-silylcarbinols with o-halogen aromatic ketones,which enables rapid and modular synthesis of six-membered carbocyclic spirooxindoles in high yields with excellent functional group tolerance(>50 examples).Mechanistic experiments revealed that this reaction involved a Peterson olefination,Michael addition and intramolecular C(sp^(3))arylation cascade.The variegated synthetic derivatization of target products and successful construction of bioactive molecules further illustrate the synthetic potential in spirooxindole-related drug discovery.