Electrocatalytic NO reduction to NH_(3)(NORR)is regarded as an appealing strategy for both sustainable NH_(3)production and harmful NO abatement,but the development of highly active and selective electrocatalysts to b...Electrocatalytic NO reduction to NH_(3)(NORR)is regarded as an appealing strategy for both sustainable NH_(3)production and harmful NO abatement,but the development of highly active and selective electrocatalysts to boost such a complex multiple proton-coupled electron-transferred process still remains a challenge.展开更多
We report a detailed study of the magnetic and relaxation properties of a series of oxovanadium(Ⅳ)complexes comprising the aqua ion[VO(H_(2)O)_(5)]^(2+)and[VO(ox)_(2)]^(2-)(ox=oxalate),[VO(nta)]-(nta=nitrilotriacetat...We report a detailed study of the magnetic and relaxation properties of a series of oxovanadium(Ⅳ)complexes comprising the aqua ion[VO(H_(2)O)_(5)]^(2+)and[VO(ox)_(2)]^(2-)(ox=oxalate),[VO(nta)]-(nta=nitrilotriacetate),[VO(dtpa)]^(3-)(dtpa=diethylenetriaminepentaacetate)and[VO(acac)_(2)](acac=acetylacetonato)in solution.The complexes were characterized using continuous wave(X-band)and pulsed(Q-band)EPR measurements and ^(1)H nuclear magnetic relaxation dispersion(NMRD)studies in the 0.01-120 MHz ^(1)H Larmor frequency range.The ^(51)V A-tensor parameters obtained from the analysis of EPR spectra are in good agreement with those obtained using theoretical calculations at the DFT and coupled-cluster levels(DLPNO-CCSD),while g-tensors were obtained with CASSCF/NEVPT2 calculations.EPR measurements reveal significant differences in the electronic T_(1)^(e) and T_(m)^(e) relaxation times,with[VO(acac)_(2)]showing a markedly different behaviour due to the trans coordination geometry.The NMRD profiles measured at different temperatures have contributions from both the outer-and inner-sphere mechanisms,with the latter showing contributions from the dipolar and scalar mechanisms.The rotational correlation times(τ_(R))obtained from the fitting of NMRD and EPR data are in good mutual agreement.The scalar mechanism depends on the hyperfine coupling constants of the coordinated water molecule H_(a_(iso)),which were obtained from the fitting of the NMRD profiles and DFT calculations.Finally,the analysis of the data provided information on the exchange rate of coordinated water molecules,which display mean residence times of ~7-17μs at 298 K.展开更多
A comparison of the results of a computational simulation and an experimental measurement indicates a good agreement between them： the bowed blade lowers the energy loss coefficient of engine by 11% in the simulation...A comparison of the results of a computational simulation and an experimental measurement indicates a good agreement between them： the bowed blade lowers the energy loss coefficient of engine by 11% in the simulation and by 13% in the measurement. To further discuss the application conditions of bowed blade in compressor, with incidence equal to zero and other boundary conditions unchanged, a computational investigations on four series of linear stators with different aerofoil turning angles are achieved. It is found that the bowed blade has much positive effect in high airfoil turning angle cascade, for example, the optimal retrofit of 30° bow angle highly reduces the energy loss coefficient by 17.9%, when the aerofoil turning angle is 59.5 °. But the optimal retrofit of 15° has only 0.7% reduction when the aerofoil turning angle is 39.5°, or even the compressor performance will get worse with the bow angle gradually increasing. Consequently, it is verified that the turning angle is one of the important factors to decide whether to apply the bowed blade into compressor at low Math number.展开更多
A series of donor–acceptor type trans-A_(2)B_(2)porphyrins and their Zn(II)and Pd(II)complexes 5–13 have been synthesized and characterized by various spectroscopic techniques.The effect of the donor moieties(e.g.,N...A series of donor–acceptor type trans-A_(2)B_(2)porphyrins and their Zn(II)and Pd(II)complexes 5–13 have been synthesized and characterized by various spectroscopic techniques.The effect of the donor moieties(e.g.,N-butylcarbazole,N-butylphenothiazine,and triphenylamine)on the spectroscopic properties of the porphyrins has been studied.展开更多
In order to obtain a multifunctional oilfield agent with both corrosion inhibition and oil displacement functions,a polymer with benzene ring structures is synthesized based on polyacrylamide(PAM)and used as inhibitor...In order to obtain a multifunctional oilfield agent with both corrosion inhibition and oil displacement functions,a polymer with benzene ring structures is synthesized based on polyacrylamide(PAM)and used as inhibitor for the first time.Methods including electrochemistry,weight loss and theoretical calculations are used to study the inhibition effect for P110 steel in 1.0 M HCl.The experimental results show that the modified polymer poly-(Z)-N-benzylidenepropionamide(PBAM)has excellent inhibition effects,and the maximum efficiency can reach 90.62%in impedance spectroscopy tests.The benzene ring structure added in the modified polymer providesπelectrons for the adsorption of inhibitor on metal surface,strengthens the adsorption,and thus brings a better corrosion inhibition effect.In addition to the corrosion inhibition performance,the viscosity-increasing effect of PBAM is evaluated.The results show that the addition of benzene ring not only enhances the corrosion inhibition effect,but also brings temperature resistance to the polymer.However,the salt tolerance of the polymer is affected,the synthesized PBAM which viscosity can above 500 m Pa s at 140℃ is suitable for high temperature and low salinity environment.The modified polyacrylamide has satisfactory corrosion inhibition and oil displacement performance,which provides a new idea for the development of oilfield chemistry.展开更多
Background:Lawsonia inermis has been widely reported to be used as an herbal treatment for Malaria.However,despite several experimental studies about its antimalarial activities,the approach through which the herbal p...Background:Lawsonia inermis has been widely reported to be used as an herbal treatment for Malaria.However,despite several experimental studies about its antimalarial activities,the approach through which the herbal plant suppresses plasmodium infection is yet to be found.Consequently,this study uses computational approaches to understand the biological targets and pathways involved in the antiplasmodial activities of Lawsonia inermis compounds.Methods:The Gas Chromatography-Mass Spectrometry technique identified the phytocompounds present in the herbal plant.GeneCards,OMIM,and NCBI databases were explored to collate target proteins for further network pharmacology analysis.The phytocompounds were subjected to Absorption,Distribution,Metabolism,Excretion and Toxicity(ADMET)and druglikeness analysis.The STRING algorithm and Cytoscape were employed to develop and analyze the relationships among target proteins and compounds/targets/pathways network of the putative targets of the phytocompounds.Further computational analysis was carried out to identify potential drug leads.Results:Based on the Network Pharmacology studies,phytocompounds in Lawsonia inermis exhibit antiplasmodial activity by interacting with therapeutic genes that play essential roles in metabolism and signaling pathways.Notable among the genes are MMP9,MAPK1,HMOX1 and IDO1.Meanwhile,the most influenced pathways include the metabolic pathway,PI3K-Akt signaling pathway,and HIF-1 signaling pathway.ADMET analysis,molecular docking analysis,and molecular dynamics simulation revealed that 3-phenyl-2-Isoxazoline and 2-Dimethylamino-3’-methoxyacetophenone are recommendable drug leads for Malaria treatment as they form stable and favorable complexes with Matrix metalloproteinase-9(MMP9)target.Conclusion:The 3-phenyl-2-Isoxazoline and 2-Dimethylamino-3’-methoxyacetophenone phytocompounds from Lawsonia inermis herbal plant are predicted as antimalarial drug candidates and recommended for further wet-lab studies.展开更多
Through deriving expressions relating the dip-angle ( m) of the lower boundary of a layer to the acoustic velocity (υm) of the layer and other pre-determinable parameters, υm and m can be taken as simultaneously ite...Through deriving expressions relating the dip-angle ( m) of the lower boundary of a layer to the acoustic velocity (υm) of the layer and other pre-determinable parameters, υm and m can be taken as simultaneously iterative variables while solving Shah 's equations . Consequently the previous method of computing υm and m presented by ZHANG S . is improved [1] , and the accuracy of solutions increased greatly.展开更多
Cortical spreading depression （CSD） is an important experimental model for diseases such as stroke, epilepsy and migraine. Previous observations indicated that the amplitude and velocity of the typical direct curren...Cortical spreading depression （CSD） is an important experimental model for diseases such as stroke, epilepsy and migraine. Previous observations indicated that the amplitude and velocity of the typical direct current potential shift during repetitive CSD waves were varying. The recovery state of the tissue was found related with the variation of successive CSD waves. A computational model in this paper aimed to investigate the role of relative refractory period of CSD. This model simulated that continuous injection of KCI solution induced repetitive CSD waves. The first CSD wave often had a larger amplitude and faster velocity than those of the succeeding secondary waves. The relative refractory period lasted much longer than the recovery of ions turbulence. If the induction interval was long enough for recovery, a series of CSD waves would have the same profile asthe first one. In the relative refractory period, an early stimulation might lead to a late initiation of CSD, i.e., ＂haste makes waste＂. The amplitude and velocity of CSD waves were found increasing with the initiation interval and asymptotic to those of the first CSD wave. This study verified that the propagation dynamics of CSD waves is modulated by the relative refractory period. It suggested that the refractory period is critical for preventing undesirable CSD waves.展开更多
The aim of this study is to understand the judicial reasoning process of anti-discrimination jurisprudence by utilizing a hybrid computational model.The advancement of hybrid computational legal studies that combine“...The aim of this study is to understand the judicial reasoning process of anti-discrimination jurisprudence by utilizing a hybrid computational model.The advancement of hybrid computational legal studies that combine“law-as-code”and“law-as-data”approaches have led to promising techniques for tackling complex legal reasoning tasks as multifactor judicial reasoning standards.Following this hybrid model,this study conducts a statistical and multilayer perceptron(MLP)analysis of the judicial reasoning process of the multifactor Arlington Heights discriminatory purpose test based on an original hand-coded dataset of discrimination cases.The results of the study show that“sequence of events”predominates the other factors for predicting the outcome of discrimination cases,with“statistical impact”and“historical background”showing particularly weak effect on the outcome.Results show that completely removing the factor of disparate statistical impact(Impact)actually improves confidence in predicting discrimination.The conclusion of the study suggests that courts fail to give either disparate statistical impact or historical record of discrimination any meaningful cumulative import in determining discriminatory purpose.I conclude by observing the benefits of hybrid computational legal studies on interrogating more normative values in the law like transparency,fairness,and procedural justice.展开更多
Caralluma edulis is a leafless succulent herb native to India and Pakistan,where it is used as emergency food and as potential herbal medicine.It was investigated for its bioactive chemicals and further medicinal prop...Caralluma edulis is a leafless succulent herb native to India and Pakistan,where it is used as emergency food and as potential herbal medicine.It was investigated for its bioactive chemicals and further medicinal properties.The objective of the current study was to accomplish the chemical and biological characterization of C.edulis.Chemical profiling was done through estimation of total bioactive contents and UHPLMS analysis.Biological screening was achieved through six different antioxidant and enzyme inhibition assays.Estimation of its phenolic and flavonoid contents revealed that ethyl acetate fraction(Ce-E)contains 14.15 mg GAE/g extract and 26.13 mg RE/g extract of phenolics and flavonoids,respectively,followed by the methanolic(Ce-M)and the water(Ce-W)soluble fractions.In free radical inhibitory assays,Ce-E fraction also exhibited highest activity(DPPH:19.72 mg TE/g extract,ABTS:48.66 mg TE/g extract)followed by Ce-M,whereas,in CUPRAC and FRAP assays,all the extracts,except water fraction,exhibited nearly equal potential in the range of 53.85–57.96 and 25.42–32.12 mg TE/g extract,respectively.In metal chelating antioxidant assay,only Ce-M and Ce-W fractions displayed considerable activities(25.88 and 23.55 mg EDTAE/g extract respectively),whereas,Ce-H exhibited the highest activity in phosphomolybdenum assay(1.03 mmolTE/g extract),against BChE(6.43 mg GALAE/g extract),α-glucosidase andα-amylase(6.98 and 0.47 mmol ACAE/g,respectively)and tyrosinase(64.46 mg KAE/g extract)enzymes.Ce-M and Ce-E also exhibited significant activity against tyrosinase(59.85 and 58.40 mg KAE/g extract,respectively).Crude methanolic extract(Ce-M)was analyzed to unveil its secondary metabolic picture;the UHPLCMS analysis discloses 105 compounds as phenolic acids,flavonoids,steroids and their glycosides,which makes the C.edulis extract a strong candidate for nutraceutical and functional food ingredient.Some of the metabolites were docked against all the tested enzymes to predict mode of actions and to substantiate the pharmaceutical nature of C.edulis.展开更多
Eight novel neonicotinoids N-oxide analogues were designed and synthesized. All the compounds have been identified by 1H NMR and HRMS. The N-oxide analogues exhibit high insecticidal activity against cowpea aphids （A...Eight novel neonicotinoids N-oxide analogues were designed and synthesized. All the compounds have been identified by 1H NMR and HRMS. The N-oxide analogues exhibit high insecticidal activity against cowpea aphids （Aphis craccivora） at 250 mg,L-1. The influence of N-oxide formation on the biological activity was elucidated by computational chemical study, and it indicated that the water bridge hydrogen bonding network was broken due to the influence of the O atom connected with the pyridine ring.展开更多
Acceptorless dehydrogenation (AD) that uses non-toxic reagents and produces no waste is a type of catalytic reactions toward green chemistry. Acceptorless alcohol dehydrogenation (AAD) can serve as a key step in const...Acceptorless dehydrogenation (AD) that uses non-toxic reagents and produces no waste is a type of catalytic reactions toward green chemistry. Acceptorless alcohol dehydrogenation (AAD) can serve as a key step in constructing new bonds such as C-C and C-N bonds in which alcohols need to be activated into more reactive ketones or aldehydes. AD reactions also can be utilized for hydrogen production from biomass or its fermentation products (mainly alcohols). Reversible hydrogenation/ dehy-drogenation with hydrogen uptake/release is crucial to realization of the potential organic hydride hydrogen storage. In this article, we review the recent computational mechanistic studies of the AD reactions catalyzed by various transition metal complexes as well as the experimental developments. These reactions include acceptorless alcohol dehydrogenations, reversible dehydrogenation/hydrogenation of nitrogen heterocycles, dehydrogenative coupling reactions of alcohols and amines to construct C-N bonds, and dehydrogenative coupling reactions of alcohols and unsaturated substrates to form C-C bonds. For the catalysts possessing metal-ligand bifunctional active sites (such as 28, 45, 86, 87, and 106 in the paper), the dehydrogenations prefer the "bifunctional double hydrogen transfer" mechanism rather than the generally accepted-H elimination mechanism. However, methanol dehydrogenation involved in the C-C coupling reaction of methanol and allene, catalyzed by the iridium complex 121, takes place via the-H elimination mechanism, because the Lewis basicity of either the-allyl moiety or the carboxyl group of the ligand is too weak to exert high Lewis basic reactivity. Unveiling the catalytic mechanisms of AD reactions could help to develop new catalysts.展开更多
Herein we report the synthesis,characterization,and initial reactivity of homoleptic yttrium and lanthanum complexes of bis(phosphine-oxide)methanides,H^(R)L-(R=Me,Ph;RE(HPhL)3 and RE2(HMeL)6).Our combined experimenta...Herein we report the synthesis,characterization,and initial reactivity of homoleptic yttrium and lanthanum complexes of bis(phosphine-oxide)methanides,H^(R)L-(R=Me,Ph;RE(HPhL)3 and RE2(HMeL)6).Our combined experimental and computational studies reveal rich structural diversity dictated by R-group and rare-earth,and the complexes are highly fluxional in solution,even at-80℃.Computational studies provide quantitative insight into the extensive negative hyperconjugation between the methanide lonepair and theσ*(P-R)andσ*(P-O).These interactions provide substantial stabilization of coordinated H^(R)L-,yet leave significant charge density at the methanide carbon.The stabilization energies are insenstive to ligand conformation,which contributes to the range of accessible binding modes,structures,and dynamic solution behavior.The largely localized anionic charge leads to strongly nucleophilic and Brønsted-basic reactivity of the methanide.This is demonstrated by the first report of a rare-earth promoted Horner-Wittig reaction and rapid reactivity of Y(H^(Ph)L)_(3) and Y_(2)(H^(Me)L)_(6) with MeOH/MeOD.The rapid acid-base reactivity of Y(H^(Ph)L)_(3) with MeOH supports a lowering of the effective pKa of a protic Lewis base by>6 orders of magnitude upon binding to Y(H^(Ph)L)_(3),and implies that multifunctional reactivity(Lewis-acid/Brønsted-base)may be possible.Our studies suggest that a rich set of stoichiometric and catalytic reactivity might be realized with these otherwise overlooked fragments.展开更多
The first chlororuthenacyclopentatrienes have been realized by the reactions of RuCl2(PPh3)3 with o-phenyldiyne derivatives in the presence of excess HCl.The structures of the unique chlororuthenacycles were fully cha...The first chlororuthenacyclopentatrienes have been realized by the reactions of RuCl2(PPh3)3 with o-phenyldiyne derivatives in the presence of excess HCl.The structures of the unique chlororuthenacycles were fully characterized using spectroscopic data and X-ray diffraction.In addition,computational studies provided evidence for their aromatic character,making them an important supplement to the rare aromatic ruthenacycle family.展开更多
A new bcu-MOF based upon a C2v-symmetrical[Cu_(4)Cl(COO)_(4)N_(8)]cluster,[Cu_(4)(Cl−)(L)_(4)·4H_(2)O]·(DMA^(+))·xDMF·yMeOH(SNNU-Bai66,SNNU-Bai=Shaanxi Normal University Bai's group),has been s...A new bcu-MOF based upon a C2v-symmetrical[Cu_(4)Cl(COO)_(4)N_(8)]cluster,[Cu_(4)(Cl−)(L)_(4)·4H_(2)O]·(DMA^(+))·xDMF·yMeOH(SNNU-Bai66,SNNU-Bai=Shaanxi Normal University Bai's group),has been sucessfully synthesized.By post-synthetic ion exchange experiments for the preparation of phases to be activated successfully,two new anionic derivatives,[Cu_(4)(Cl^(−))(L)_(4)·4H_(2)O]·[Li(H_(2)O)_(4)]^(+)·xDMK(Li^(+)-SNNU-Bai66,DMK=dimethyl ketone)and[Cu4(Cl−)(L)_(4)·_(4)H_(2)O]·(DMA^(+))·xDMK(DMA^(+)-SNNU-Bai66,DMA^(+)=Me_(2)NH_(2)),have been achieved and their selective CO_(2)or CH_(4)adsorptions over N_(2)gas have been systematically investigated in depth by both experimental and simulation studies.With the ionic pore surface and counterions cooperating with Lewis base N or O sites of the organic ligands in both Li^(+)-SNNU-Bai66 and DMA^(+)-SNNU-Bai66,the two MOFs exhibit highly selective CO_(2)and CH4 adsorption,especially for CH4 gas.Moreover,with the counterion being tuned from Li(H_(2)O)_(4)+to DMA^(+),selective CO_(2)adsorption properties are slightly optimized due to the higher polarizability of DMA^(+)and the preferred adsorption site changing from site I[the opposite side of Cl−toward Li(H_(2)O)_(4)^(+)]in Li^(+)-SNNU-Bai66 to site II(the position between the Hc atom of the L1 ligand and DMA^(+))in DMA^(+)-SNNU-Bai66,whereas those of CH_(4) of both MOFs are similar due to their having the same preferred adsorption site,namely,site I[the opposite side of Cl^(−)toward DMA^(+)or Li(H_(2)O)_(4)^(+)],in their frameworks.This work may further enrich the investigation of anionic MOFs in the field of selective gas adsorption with their inherent natures being more definitely displayed.展开更多
A deeper computational mechanistic study of an environmentally friendly metal-free CO_(2)reduction process towards obtaining methanol is presented,employing a previously tested kind of intramolecular frustrated Lewis ...A deeper computational mechanistic study of an environmentally friendly metal-free CO_(2)reduction process towards obtaining methanol is presented,employing a previously tested kind of intramolecular frustrated Lewis pair(2-[bis(R)boryl]-N,N-dimethylaniline)as the catalyst and H_(2)as the reducing agent.The Lewis acid strength of the electrophilic boron atom was adjusted to facilitate hydride release by changing the R group.展开更多
Ice,a ubiquitous substance in nature,exhibits diverse forms under varying temperature and pressure conditions.However,our understanding of ice polymorphs remains incomplete.The directional nature of hydrogen bonding a...Ice,a ubiquitous substance in nature,exhibits diverse forms under varying temperature and pressure conditions.However,our understanding of ice polymorphs remains incomplete.The directional nature of hydrogen bonding and the complexity of the networks they form pose significant challenges to computational studies of ice structures.In this work,we present an extensive exploration of ice polymorphs under pressure conditions ranging from 1 bar to 10 GPa.We employ an advanced crystal-structure-prediction scheme that integrates an evolutionary algorithm,an active-learning deep neural network potential,and molecular dynamics simulations with ab initio accuracy.Among the 131,481 predicted structures,we successfully identify all experimentally known ice phases within the target pressure range,including the particularly challenging ice IV and V.These phases feature highly intricate H-bond networks,which have hindered previous efforts to fully explore ice structures.Additionally,we identify 34 new ice polymorphs that are potential candidates for experimental discovery.Notably,we predict the existence of a new stable ice phase,ice L,within the temperature range of 253–291 K and pressure range of 0.38–0.57 GPa,exhibiting a unique topology unseen in any known crystals.Our findings highlight the potential for experimental discovery of new ice phases.Furthermore,our approach can be applied to other complex systems,particularly those with network structures.展开更多
An unusual negative 1H NMR chemical shift of methyl group was discovered in condensation product of isoco-palane diterpenoid with p-toluenesulfonyl hydrazide.2D NMR,computational studies and single-crystal X-ray dif-f...An unusual negative 1H NMR chemical shift of methyl group was discovered in condensation product of isoco-palane diterpenoid with p-toluenesulfonyl hydrazide.2D NMR,computational studies and single-crystal X-ray dif-fraction analysis showed that the C-20 methyl group was shielded.展开更多
基金supported by the Natural Science Foundation of Heilongjiang Province of China(TD2020B001)the Natural Science Funds for Distinguished Young Scholar of Heilongjiang Province(no.JC2018004).
文摘Electrocatalytic NO reduction to NH_(3)(NORR)is regarded as an appealing strategy for both sustainable NH_(3)production and harmful NO abatement,but the development of highly active and selective electrocatalysts to boost such a complex multiple proton-coupled electron-transferred process still remains a challenge.
基金the financial support from the Ministero dell’Universitàe della Ricerca(PRIN 2017A2KEPL project)Ministerio de Ciencia e Innovación(PID2019-104626GB-I00)Xunta de Galicia(Grant ED431B 2020/52)for generous financial support.
文摘We report a detailed study of the magnetic and relaxation properties of a series of oxovanadium(Ⅳ)complexes comprising the aqua ion[VO(H_(2)O)_(5)]^(2+)and[VO(ox)_(2)]^(2-)(ox=oxalate),[VO(nta)]-(nta=nitrilotriacetate),[VO(dtpa)]^(3-)(dtpa=diethylenetriaminepentaacetate)and[VO(acac)_(2)](acac=acetylacetonato)in solution.The complexes were characterized using continuous wave(X-band)and pulsed(Q-band)EPR measurements and ^(1)H nuclear magnetic relaxation dispersion(NMRD)studies in the 0.01-120 MHz ^(1)H Larmor frequency range.The ^(51)V A-tensor parameters obtained from the analysis of EPR spectra are in good agreement with those obtained using theoretical calculations at the DFT and coupled-cluster levels(DLPNO-CCSD),while g-tensors were obtained with CASSCF/NEVPT2 calculations.EPR measurements reveal significant differences in the electronic T_(1)^(e) and T_(m)^(e) relaxation times,with[VO(acac)_(2)]showing a markedly different behaviour due to the trans coordination geometry.The NMRD profiles measured at different temperatures have contributions from both the outer-and inner-sphere mechanisms,with the latter showing contributions from the dipolar and scalar mechanisms.The rotational correlation times(τ_(R))obtained from the fitting of NMRD and EPR data are in good mutual agreement.The scalar mechanism depends on the hyperfine coupling constants of the coordinated water molecule H_(a_(iso)),which were obtained from the fitting of the NMRD profiles and DFT calculations.Finally,the analysis of the data provided information on the exchange rate of coordinated water molecules,which display mean residence times of ~7-17μs at 298 K.
基金National Natural Science Foundation of China(50236020).
文摘A comparison of the results of a computational simulation and an experimental measurement indicates a good agreement between them： the bowed blade lowers the energy loss coefficient of engine by 11% in the simulation and by 13% in the measurement. To further discuss the application conditions of bowed blade in compressor, with incidence equal to zero and other boundary conditions unchanged, a computational investigations on four series of linear stators with different aerofoil turning angles are achieved. It is found that the bowed blade has much positive effect in high airfoil turning angle cascade, for example, the optimal retrofit of 30° bow angle highly reduces the energy loss coefficient by 17.9%, when the aerofoil turning angle is 59.5 °. But the optimal retrofit of 15° has only 0.7% reduction when the aerofoil turning angle is 39.5°, or even the compressor performance will get worse with the bow angle gradually increasing. Consequently, it is verified that the turning angle is one of the important factors to decide whether to apply the bowed blade into compressor at low Math number.
基金support from SERB(EMR/2015/000779)Govt.of India,is greatly acknowledged.SD and NB thank IIT Gandhinagar for a fellowship and infrastructural support.PCJ acknowledges CUG for providing basic computational facilities and UGC,New Delhi for start-up grants.HRB thanks UGC for fiscal assistance.The work in Japan was supported by Grantin-Aids(15K13646 to H.F.and 16K05700 to M.I.)from the Japan Society for the Promotion of Science(JSPS).
文摘A series of donor–acceptor type trans-A_(2)B_(2)porphyrins and their Zn(II)and Pd(II)complexes 5–13 have been synthesized and characterized by various spectroscopic techniques.The effect of the donor moieties(e.g.,N-butylcarbazole,N-butylphenothiazine,and triphenylamine)on the spectroscopic properties of the porphyrins has been studied.
文摘In order to obtain a multifunctional oilfield agent with both corrosion inhibition and oil displacement functions,a polymer with benzene ring structures is synthesized based on polyacrylamide(PAM)and used as inhibitor for the first time.Methods including electrochemistry,weight loss and theoretical calculations are used to study the inhibition effect for P110 steel in 1.0 M HCl.The experimental results show that the modified polymer poly-(Z)-N-benzylidenepropionamide(PBAM)has excellent inhibition effects,and the maximum efficiency can reach 90.62%in impedance spectroscopy tests.The benzene ring structure added in the modified polymer providesπelectrons for the adsorption of inhibitor on metal surface,strengthens the adsorption,and thus brings a better corrosion inhibition effect.In addition to the corrosion inhibition performance,the viscosity-increasing effect of PBAM is evaluated.The results show that the addition of benzene ring not only enhances the corrosion inhibition effect,but also brings temperature resistance to the polymer.However,the salt tolerance of the polymer is affected,the synthesized PBAM which viscosity can above 500 m Pa s at 140℃ is suitable for high temperature and low salinity environment.The modified polyacrylamide has satisfactory corrosion inhibition and oil displacement performance,which provides a new idea for the development of oilfield chemistry.
文摘Background:Lawsonia inermis has been widely reported to be used as an herbal treatment for Malaria.However,despite several experimental studies about its antimalarial activities,the approach through which the herbal plant suppresses plasmodium infection is yet to be found.Consequently,this study uses computational approaches to understand the biological targets and pathways involved in the antiplasmodial activities of Lawsonia inermis compounds.Methods:The Gas Chromatography-Mass Spectrometry technique identified the phytocompounds present in the herbal plant.GeneCards,OMIM,and NCBI databases were explored to collate target proteins for further network pharmacology analysis.The phytocompounds were subjected to Absorption,Distribution,Metabolism,Excretion and Toxicity(ADMET)and druglikeness analysis.The STRING algorithm and Cytoscape were employed to develop and analyze the relationships among target proteins and compounds/targets/pathways network of the putative targets of the phytocompounds.Further computational analysis was carried out to identify potential drug leads.Results:Based on the Network Pharmacology studies,phytocompounds in Lawsonia inermis exhibit antiplasmodial activity by interacting with therapeutic genes that play essential roles in metabolism and signaling pathways.Notable among the genes are MMP9,MAPK1,HMOX1 and IDO1.Meanwhile,the most influenced pathways include the metabolic pathway,PI3K-Akt signaling pathway,and HIF-1 signaling pathway.ADMET analysis,molecular docking analysis,and molecular dynamics simulation revealed that 3-phenyl-2-Isoxazoline and 2-Dimethylamino-3’-methoxyacetophenone are recommendable drug leads for Malaria treatment as they form stable and favorable complexes with Matrix metalloproteinase-9(MMP9)target.Conclusion:The 3-phenyl-2-Isoxazoline and 2-Dimethylamino-3’-methoxyacetophenone phytocompounds from Lawsonia inermis herbal plant are predicted as antimalarial drug candidates and recommended for further wet-lab studies.
文摘Through deriving expressions relating the dip-angle ( m) of the lower boundary of a layer to the acoustic velocity (υm) of the layer and other pre-determinable parameters, υm and m can be taken as simultaneously iterative variables while solving Shah 's equations . Consequently the previous method of computing υm and m presented by ZHANG S . is improved [1] , and the accuracy of solutions increased greatly.
文摘Cortical spreading depression （CSD） is an important experimental model for diseases such as stroke, epilepsy and migraine. Previous observations indicated that the amplitude and velocity of the typical direct current potential shift during repetitive CSD waves were varying. The recovery state of the tissue was found related with the variation of successive CSD waves. A computational model in this paper aimed to investigate the role of relative refractory period of CSD. This model simulated that continuous injection of KCI solution induced repetitive CSD waves. The first CSD wave often had a larger amplitude and faster velocity than those of the succeeding secondary waves. The relative refractory period lasted much longer than the recovery of ions turbulence. If the induction interval was long enough for recovery, a series of CSD waves would have the same profile asthe first one. In the relative refractory period, an early stimulation might lead to a late initiation of CSD, i.e., ＂haste makes waste＂. The amplitude and velocity of CSD waves were found increasing with the initiation interval and asymptotic to those of the first CSD wave. This study verified that the propagation dynamics of CSD waves is modulated by the relative refractory period. It suggested that the refractory period is critical for preventing undesirable CSD waves.
文摘The aim of this study is to understand the judicial reasoning process of anti-discrimination jurisprudence by utilizing a hybrid computational model.The advancement of hybrid computational legal studies that combine“law-as-code”and“law-as-data”approaches have led to promising techniques for tackling complex legal reasoning tasks as multifactor judicial reasoning standards.Following this hybrid model,this study conducts a statistical and multilayer perceptron(MLP)analysis of the judicial reasoning process of the multifactor Arlington Heights discriminatory purpose test based on an original hand-coded dataset of discrimination cases.The results of the study show that“sequence of events”predominates the other factors for predicting the outcome of discrimination cases,with“statistical impact”and“historical background”showing particularly weak effect on the outcome.Results show that completely removing the factor of disparate statistical impact(Impact)actually improves confidence in predicting discrimination.The conclusion of the study suggests that courts fail to give either disparate statistical impact or historical record of discrimination any meaningful cumulative import in determining discriminatory purpose.I conclude by observing the benefits of hybrid computational legal studies on interrogating more normative values in the law like transparency,fairness,and procedural justice.
基金King Khalid University of Saudi Arabia extend their appreciation to Deanship of Scientific Research for financial support through project RGP.1/318/43support from Poison Control and Medical Forensic Chemistry Centre,Ministry of Health,Asir Region,Saudi Arabia.
文摘Caralluma edulis is a leafless succulent herb native to India and Pakistan,where it is used as emergency food and as potential herbal medicine.It was investigated for its bioactive chemicals and further medicinal properties.The objective of the current study was to accomplish the chemical and biological characterization of C.edulis.Chemical profiling was done through estimation of total bioactive contents and UHPLMS analysis.Biological screening was achieved through six different antioxidant and enzyme inhibition assays.Estimation of its phenolic and flavonoid contents revealed that ethyl acetate fraction(Ce-E)contains 14.15 mg GAE/g extract and 26.13 mg RE/g extract of phenolics and flavonoids,respectively,followed by the methanolic(Ce-M)and the water(Ce-W)soluble fractions.In free radical inhibitory assays,Ce-E fraction also exhibited highest activity(DPPH:19.72 mg TE/g extract,ABTS:48.66 mg TE/g extract)followed by Ce-M,whereas,in CUPRAC and FRAP assays,all the extracts,except water fraction,exhibited nearly equal potential in the range of 53.85–57.96 and 25.42–32.12 mg TE/g extract,respectively.In metal chelating antioxidant assay,only Ce-M and Ce-W fractions displayed considerable activities(25.88 and 23.55 mg EDTAE/g extract respectively),whereas,Ce-H exhibited the highest activity in phosphomolybdenum assay(1.03 mmolTE/g extract),against BChE(6.43 mg GALAE/g extract),α-glucosidase andα-amylase(6.98 and 0.47 mmol ACAE/g,respectively)and tyrosinase(64.46 mg KAE/g extract)enzymes.Ce-M and Ce-E also exhibited significant activity against tyrosinase(59.85 and 58.40 mg KAE/g extract,respectively).Crude methanolic extract(Ce-M)was analyzed to unveil its secondary metabolic picture;the UHPLCMS analysis discloses 105 compounds as phenolic acids,flavonoids,steroids and their glycosides,which makes the C.edulis extract a strong candidate for nutraceutical and functional food ingredient.Some of the metabolites were docked against all the tested enzymes to predict mode of actions and to substantiate the pharmaceutical nature of C.edulis.
基金This work was financially supported by National Basic Research Program of China （973 Program, 2010CB126100）, National High Technology Research and Development Program of China （863 Program, 2011AA10A207）. This work was also partly supported by National Key Technology R＆D Program of China （2011BAE06B01）, National Natural Science Foundation of China （20802018）, Shanghai Foundation of Science and Technology （09391911800, 08391911600, 08ZR1406500）, Doctoral Program of Higher Education （200802511002）, Shanghai Leading Academic Discipline Project, Project Number： B507 and the Fundamental Research Funds for the Central Universities. This work was supported by ＂Special Fund for Agro-scientific Research in the Public Interest （201103007）＂.
文摘Eight novel neonicotinoids N-oxide analogues were designed and synthesized. All the compounds have been identified by 1H NMR and HRMS. The N-oxide analogues exhibit high insecticidal activity against cowpea aphids （Aphis craccivora） at 250 mg,L-1. The influence of N-oxide formation on the biological activity was elucidated by computational chemical study, and it indicated that the water bridge hydrogen bonding network was broken due to the influence of the O atom connected with the pyridine ring.
基金supported by the Chinese Academy of Sciencesthe National Natural Science Foundation of China (20973197 and 21173263)
文摘Acceptorless dehydrogenation (AD) that uses non-toxic reagents and produces no waste is a type of catalytic reactions toward green chemistry. Acceptorless alcohol dehydrogenation (AAD) can serve as a key step in constructing new bonds such as C-C and C-N bonds in which alcohols need to be activated into more reactive ketones or aldehydes. AD reactions also can be utilized for hydrogen production from biomass or its fermentation products (mainly alcohols). Reversible hydrogenation/ dehy-drogenation with hydrogen uptake/release is crucial to realization of the potential organic hydride hydrogen storage. In this article, we review the recent computational mechanistic studies of the AD reactions catalyzed by various transition metal complexes as well as the experimental developments. These reactions include acceptorless alcohol dehydrogenations, reversible dehydrogenation/hydrogenation of nitrogen heterocycles, dehydrogenative coupling reactions of alcohols and amines to construct C-N bonds, and dehydrogenative coupling reactions of alcohols and unsaturated substrates to form C-C bonds. For the catalysts possessing metal-ligand bifunctional active sites (such as 28, 45, 86, 87, and 106 in the paper), the dehydrogenations prefer the "bifunctional double hydrogen transfer" mechanism rather than the generally accepted-H elimination mechanism. However, methanol dehydrogenation involved in the C-C coupling reaction of methanol and allene, catalyzed by the iridium complex 121, takes place via the-H elimination mechanism, because the Lewis basicity of either the-allyl moiety or the carboxyl group of the ligand is too weak to exert high Lewis basic reactivity. Unveiling the catalytic mechanisms of AD reactions could help to develop new catalysts.
基金JRR acknowledges Brown University for financial support of this work.KCC thanks Matthew Lueckheide for samples of decamethylferroceneXiang Dong for helpful discussions related to the DOSY studiesJRR and AMB thank Dr Mehmed Z.Ertem for helpful discussions related to the computational studies.
文摘Herein we report the synthesis,characterization,and initial reactivity of homoleptic yttrium and lanthanum complexes of bis(phosphine-oxide)methanides,H^(R)L-(R=Me,Ph;RE(HPhL)3 and RE2(HMeL)6).Our combined experimental and computational studies reveal rich structural diversity dictated by R-group and rare-earth,and the complexes are highly fluxional in solution,even at-80℃.Computational studies provide quantitative insight into the extensive negative hyperconjugation between the methanide lonepair and theσ*(P-R)andσ*(P-O).These interactions provide substantial stabilization of coordinated H^(R)L-,yet leave significant charge density at the methanide carbon.The stabilization energies are insenstive to ligand conformation,which contributes to the range of accessible binding modes,structures,and dynamic solution behavior.The largely localized anionic charge leads to strongly nucleophilic and Brønsted-basic reactivity of the methanide.This is demonstrated by the first report of a rare-earth promoted Horner-Wittig reaction and rapid reactivity of Y(H^(Ph)L)_(3) and Y_(2)(H^(Me)L)_(6) with MeOH/MeOD.The rapid acid-base reactivity of Y(H^(Ph)L)_(3) with MeOH supports a lowering of the effective pKa of a protic Lewis base by>6 orders of magnitude upon binding to Y(H^(Ph)L)_(3),and implies that multifunctional reactivity(Lewis-acid/Brønsted-base)may be possible.Our studies suggest that a rich set of stoichiometric and catalytic reactivity might be realized with these otherwise overlooked fragments.
基金supported by the National Natural Science Foundation of China(no.21772160)the Hong Kong Research Grants Council(project no.16302322).
文摘The first chlororuthenacyclopentatrienes have been realized by the reactions of RuCl2(PPh3)3 with o-phenyldiyne derivatives in the presence of excess HCl.The structures of the unique chlororuthenacycles were fully characterized using spectroscopic data and X-ray diffraction.In addition,computational studies provided evidence for their aromatic character,making them an important supplement to the rare aromatic ruthenacycle family.
基金the National Natural Science Foundation of China(21771121)the Fundamental Research Funds for the Central Universities(No.GK201903040)for their support.
文摘A new bcu-MOF based upon a C2v-symmetrical[Cu_(4)Cl(COO)_(4)N_(8)]cluster,[Cu_(4)(Cl−)(L)_(4)·4H_(2)O]·(DMA^(+))·xDMF·yMeOH(SNNU-Bai66,SNNU-Bai=Shaanxi Normal University Bai's group),has been sucessfully synthesized.By post-synthetic ion exchange experiments for the preparation of phases to be activated successfully,two new anionic derivatives,[Cu_(4)(Cl^(−))(L)_(4)·4H_(2)O]·[Li(H_(2)O)_(4)]^(+)·xDMK(Li^(+)-SNNU-Bai66,DMK=dimethyl ketone)and[Cu4(Cl−)(L)_(4)·_(4)H_(2)O]·(DMA^(+))·xDMK(DMA^(+)-SNNU-Bai66,DMA^(+)=Me_(2)NH_(2)),have been achieved and their selective CO_(2)or CH_(4)adsorptions over N_(2)gas have been systematically investigated in depth by both experimental and simulation studies.With the ionic pore surface and counterions cooperating with Lewis base N or O sites of the organic ligands in both Li^(+)-SNNU-Bai66 and DMA^(+)-SNNU-Bai66,the two MOFs exhibit highly selective CO_(2)and CH4 adsorption,especially for CH4 gas.Moreover,with the counterion being tuned from Li(H_(2)O)_(4)+to DMA^(+),selective CO_(2)adsorption properties are slightly optimized due to the higher polarizability of DMA^(+)and the preferred adsorption site changing from site I[the opposite side of Cl−toward Li(H_(2)O)_(4)^(+)]in Li^(+)-SNNU-Bai66 to site II(the position between the Hc atom of the L1 ligand and DMA^(+))in DMA^(+)-SNNU-Bai66,whereas those of CH_(4) of both MOFs are similar due to their having the same preferred adsorption site,namely,site I[the opposite side of Cl^(−)toward DMA^(+)or Li(H_(2)O)_(4)^(+)],in their frameworks.This work may further enrich the investigation of anionic MOFs in the field of selective gas adsorption with their inherent natures being more definitely displayed.
基金postdoctoral FONDECYT grant no.3200949 for financial support.RD acknowledges FONDECYT grant no.11230753PJ acknowledges the FONDECYT grant with project no.1181914.
文摘A deeper computational mechanistic study of an environmentally friendly metal-free CO_(2)reduction process towards obtaining methanol is presented,employing a previously tested kind of intramolecular frustrated Lewis pair(2-[bis(R)boryl]-N,N-dimethylaniline)as the catalyst and H_(2)as the reducing agent.The Lewis acid strength of the electrophilic boron atom was adjusted to facilitate hydride release by changing the R group.
基金supported by the National Natural Science Foundation of China(grant nos.12374217,92370118,and 22003050)the Research Fund of the State Key Laboratory of Solidification Processing(NPU),China(grant no.2024-ZD-01)+2 种基金the Fundamental Research Funds for the Central Universities,China.The calculations were supported by the National Supercomputing Center in Xi’an,Chinathe BohriumCloud platformat DP technologythe International Center for Materials Discovery(ICMD)cluster of NPU。
文摘Ice,a ubiquitous substance in nature,exhibits diverse forms under varying temperature and pressure conditions.However,our understanding of ice polymorphs remains incomplete.The directional nature of hydrogen bonding and the complexity of the networks they form pose significant challenges to computational studies of ice structures.In this work,we present an extensive exploration of ice polymorphs under pressure conditions ranging from 1 bar to 10 GPa.We employ an advanced crystal-structure-prediction scheme that integrates an evolutionary algorithm,an active-learning deep neural network potential,and molecular dynamics simulations with ab initio accuracy.Among the 131,481 predicted structures,we successfully identify all experimentally known ice phases within the target pressure range,including the particularly challenging ice IV and V.These phases feature highly intricate H-bond networks,which have hindered previous efforts to fully explore ice structures.Additionally,we identify 34 new ice polymorphs that are potential candidates for experimental discovery.Notably,we predict the existence of a new stable ice phase,ice L,within the temperature range of 253–291 K and pressure range of 0.38–0.57 GPa,exhibiting a unique topology unseen in any known crystals.Our findings highlight the potential for experimental discovery of new ice phases.Furthermore,our approach can be applied to other complex systems,particularly those with network structures.
基金supported by National Natural Science Foundation of China(No.21302053)Science and Technology Commission of Shanghai Mu-nicipality(No.14DZ1900102)the Fundamental Research Funds for the Central University(No.WY1113007)。
文摘An unusual negative 1H NMR chemical shift of methyl group was discovered in condensation product of isoco-palane diterpenoid with p-toluenesulfonyl hydrazide.2D NMR,computational studies and single-crystal X-ray dif-fraction analysis showed that the C-20 methyl group was shielded.
