A graphical index is a numeric value corresponding to a graph which is structurally invariant and in molecular graph theory these invariants are known as topological indices. In the field of Chemical and Medical Scien...A graphical index is a numeric value corresponding to a graph which is structurally invariant and in molecular graph theory these invariants are known as topological indices. In the field of Chemical and Medical Sciences, the topological indices are used to study the chemical, biological, medical and pharmaceutical features of drugs. With reference to the previous deadly diseases, the COVID-19 pandemic has considered to be the biggest life threatening issue that modern medicines have ever tackled. COVID-19 is immedicable and even the existing treatments are only helping the certain group of sufferers. Scientists have tested available antiviral agents and got a favorable impact on recovering from pandemic. Some of these antiviral agents are remdesivir, chloroquine, hydroxychloroquine, theaflavin and dexamethasone. Keeping in view of the importance of topological indices in the study of pharmaceutical and chemical drugs, in this paper, we calculate the <em>M<sub>dn</sub></em>-Polynomial, some downhill Zagreb topological indices and some downhill Zagreb polynomials of some of the anti viral agents remdesivir, chloroquine, hydroxychloroquine, theaflavin and dexamethasone. The results thus obtained may be useful for the finding new medicine and vaccine for the treatment of COVID-19.展开更多
Solar-driven selective upgrading of lignocellulosic biomass-derived alcohols to value-added chemicals and clean fuel hydrogen(H_(2))shows great potential for tackling the energy crisis and environmental pollu-tion iss...Solar-driven selective upgrading of lignocellulosic biomass-derived alcohols to value-added chemicals and clean fuel hydrogen(H_(2))shows great potential for tackling the energy crisis and environmental pollu-tion issues.Here,we construct a MAPbBr_(3)/ReS_(2) heterostructure by embedding distorted tetragonal(1T)phase ReS_(2) nanoflowers into large-sized MAPbBr_(3) for green value-added utilization of biomass-derived alcohols.The embedded structure effectively enlarges the contact interface between the ReS_(2) and the MAPbBr_(3),and importantly,induces a strong built-in electric field aligned between the spatially well-defined MAPbBr_(3) and ReS_(2) nanoflowers.Moreover,the distorted 1T phase ReS_(2) with low work function well matches the energy band of MAPbBr_(3),forming a heterostructure with a downward band bending at the interface.These features empower the MAPbBr_(3)/ReS_(2) photocatalyst with high capability to promote charge separation and expedite the surface redox reaction.Consequently,optimal BAD and H_(2) production rates of about 1220 μmol h-1 g-1 are realized over a MAPbBr_(3)/ReS_(2) 2%sample,which are approximately 9 times greater than those of blank MAPbBr_(3).This work demonstrates the great potential of constructing an embedded transition metal dichalcogenide@metal halide perovskites heterostructure with downhill interfacial charge transfer for photocatalytic upgrading of biomass-derived alcohols.展开更多
Microseismic event location is one of the core parameters in microseismic monitoring,and the accuracy of localization will directly affect the effectiveness of engineering applications.However,limited by spatial facto...Microseismic event location is one of the core parameters in microseismic monitoring,and the accuracy of localization will directly affect the effectiveness of engineering applications.However,limited by spatial factors,the geometry of the sensor installation will be close to linear,which makes the localization equation suffer from the pathological problem,and the localization accuracy is greatly reduced.To address this problem,the reasons for the pathological problem are analyzed from the perspective of the objective function residuals and coefficient matrix.The pathological problem is caused by the combined effect of the poorer sensor array and data errors,and its residual isosurface shows a conical distribution,and as the residual value decreases,the apex of the isosurface gradually extends to the far side,and the localization results do not converge.For this reason,an improved regularized Newton downhill localization algorithm is proposed.In this method,firstly,the Newtonian downhill method is improved so that the magnitudes of the seismic source parameters are the same,and the condition number of the coefficient matrix is reduced;then,the L-curve method is used to calculate the regularization factor for the pathological equations,and the coefficient matrix is improved;finally,the pathological equations are regularized,and the seismic source coordinates are obtained by the improved Newtonian downhill method.The results of engineering applications show that compared with the traditional algorithm based on automatic of P-arrival picking,the number of effective microseismic events calculated by the proposed localization algorithm is increased by 194.7%,and the localization accuracy is substantially improved.The proposed algorithm reduces the problem of low accuracy of S-arrival picking and allows localization using only P-wave arrival.The method reduces the quality requirements of the data and significantly improves the utilization of microseismic events and positioning accuracy.展开更多
文摘A graphical index is a numeric value corresponding to a graph which is structurally invariant and in molecular graph theory these invariants are known as topological indices. In the field of Chemical and Medical Sciences, the topological indices are used to study the chemical, biological, medical and pharmaceutical features of drugs. With reference to the previous deadly diseases, the COVID-19 pandemic has considered to be the biggest life threatening issue that modern medicines have ever tackled. COVID-19 is immedicable and even the existing treatments are only helping the certain group of sufferers. Scientists have tested available antiviral agents and got a favorable impact on recovering from pandemic. Some of these antiviral agents are remdesivir, chloroquine, hydroxychloroquine, theaflavin and dexamethasone. Keeping in view of the importance of topological indices in the study of pharmaceutical and chemical drugs, in this paper, we calculate the <em>M<sub>dn</sub></em>-Polynomial, some downhill Zagreb topological indices and some downhill Zagreb polynomials of some of the anti viral agents remdesivir, chloroquine, hydroxychloroquine, theaflavin and dexamethasone. The results thus obtained may be useful for the finding new medicine and vaccine for the treatment of COVID-19.
基金National Natural Science Foundation of China(Nos.22178057 and 21905049)Natural Science Foundation of Fujian Province(Nos.2020J01201 and 2021J01197)+1 种基金Research Foundation of the Academy of Carbon Neutrality of Fujian Normal University(No.TZH2022-07)Award Program for Minjiang Scholar Professorship.
文摘Solar-driven selective upgrading of lignocellulosic biomass-derived alcohols to value-added chemicals and clean fuel hydrogen(H_(2))shows great potential for tackling the energy crisis and environmental pollu-tion issues.Here,we construct a MAPbBr_(3)/ReS_(2) heterostructure by embedding distorted tetragonal(1T)phase ReS_(2) nanoflowers into large-sized MAPbBr_(3) for green value-added utilization of biomass-derived alcohols.The embedded structure effectively enlarges the contact interface between the ReS_(2) and the MAPbBr_(3),and importantly,induces a strong built-in electric field aligned between the spatially well-defined MAPbBr_(3) and ReS_(2) nanoflowers.Moreover,the distorted 1T phase ReS_(2) with low work function well matches the energy band of MAPbBr_(3),forming a heterostructure with a downward band bending at the interface.These features empower the MAPbBr_(3)/ReS_(2) photocatalyst with high capability to promote charge separation and expedite the surface redox reaction.Consequently,optimal BAD and H_(2) production rates of about 1220 μmol h-1 g-1 are realized over a MAPbBr_(3)/ReS_(2) 2%sample,which are approximately 9 times greater than those of blank MAPbBr_(3).This work demonstrates the great potential of constructing an embedded transition metal dichalcogenide@metal halide perovskites heterostructure with downhill interfacial charge transfer for photocatalytic upgrading of biomass-derived alcohols.
基金the financial support from the National Natural Science Foundation of China(Grant no.42077263).
文摘Microseismic event location is one of the core parameters in microseismic monitoring,and the accuracy of localization will directly affect the effectiveness of engineering applications.However,limited by spatial factors,the geometry of the sensor installation will be close to linear,which makes the localization equation suffer from the pathological problem,and the localization accuracy is greatly reduced.To address this problem,the reasons for the pathological problem are analyzed from the perspective of the objective function residuals and coefficient matrix.The pathological problem is caused by the combined effect of the poorer sensor array and data errors,and its residual isosurface shows a conical distribution,and as the residual value decreases,the apex of the isosurface gradually extends to the far side,and the localization results do not converge.For this reason,an improved regularized Newton downhill localization algorithm is proposed.In this method,firstly,the Newtonian downhill method is improved so that the magnitudes of the seismic source parameters are the same,and the condition number of the coefficient matrix is reduced;then,the L-curve method is used to calculate the regularization factor for the pathological equations,and the coefficient matrix is improved;finally,the pathological equations are regularized,and the seismic source coordinates are obtained by the improved Newtonian downhill method.The results of engineering applications show that compared with the traditional algorithm based on automatic of P-arrival picking,the number of effective microseismic events calculated by the proposed localization algorithm is increased by 194.7%,and the localization accuracy is substantially improved.The proposed algorithm reduces the problem of low accuracy of S-arrival picking and allows localization using only P-wave arrival.The method reduces the quality requirements of the data and significantly improves the utilization of microseismic events and positioning accuracy.
