Computational Chemistry and Molecular Modeling Techniques for the Study of Micropeptin EI-964: Insights into Its Chemical Reactivity and Potential Pharmaceutical Properties

Micropeptin EI-964 is a cyclic peptide compound isolated from a marine cyanobacterium with potent inhibitory activity against serine proteases, particularly chymotrypsin and trypsin. It has shown promising activity against various cancer cell lines, making it a candidate for drug development. The unique structure and activity of Micropeptin EI-964 make it a promising lead compound for the development of novel serine protease inhibitors and anti-cancer drugs. Computational Chemistry and Molecular Modeling techniques can provide valuable insights into the chemical reactivity and pharmaceutical properties of Micropeptin EI-964, guiding the design and development of new compounds with enhanced bioactivity and improved drug-like properties.

Computational investigation on the molecular structure and chemical reactivity of a traditional Chinese medicine extract MK-1 molecule

MK-1 molecule(C_(16)H_(16)O_(2)),the simplest structure of vitamin K(VK)compound family,is an extract from traditional Chinese medicine Cymbopogon distans(Nees ex Steud.)Wats(Chinese name YunXiangCao),which has attracted a great deal of attention in recent years due to its antiasthmatic,antitussives and expectorant effects.To investigate the molecular structure and chemical reactivity of MK-1 molecule,computational investigations on six conformational minima structures were carried out at the MP2/6-311++G(2d,2p)level of theory.Several local reactivity descriptors including condensed Fukui function,average local ionization energy,and molecular electrostatic potential on each individual atom were determined to predict the intrinsic reactivity of MK-1 molecule.

Effect of chemical reactivity on the detonation initiation in shock accelerated flow in a confined space

The interactions of a spherical flame with an incident shock wave and its reflected shock wave in a confined space were investigated using the three-dimensional reactive Navier-Stokes equations, with emphasis placed on the effect of chemical reactivity of mixture on the flame distortion and detonation initiation after the passage of the reflected shock wave. It is shown that the spatio-temporal characteristics of detonation initiation depend highly on the chemi- cal reactivity of the mixture. When the chemical reactivity enhances, the flame can be severely distorted to form a reactive shock bifurcation structure with detonations initiating at different three-dimensional spatial locations. Moreover, the detonation initiation would occur earlier in a mixture of more enhanced reactivity. The results reveal that the detona- tions arise from hot spots in the unburned region which are initiated by the shock-detonation-transition mechanism.

Characteristics and chemical reactivity of biogenic volatile organic compounds from dominant forest species in the Jing-Jin-Ji area,China

Background:Biogenic volatile organic compounds(BVOCs)play an essential role in tropospheric atmospheric chemical reactions.There are few studies conducted on BVOCs emission of dominant forest species in the Jing-Jin-Ji area of China.Based on the field survey,forest resources data and the measured standard emission factors,the Guenther model developed in 1993(G93)was applied in this paper to estimate the emission of BVOCs from several dominant forest species(Platycladus orientalis,Quercus variabilis,Betula platyphylla,Populus tomentosa,Pinus tabuliformis,Robinia pseudoacacia,Ulmus pumila,Salix babylonica and Larix gmelinii)in the Jing-Jin-Ji area in 2017.Then the spatiotemporal emission characteristics and atmospheric chemical reactivity of these species were extensively evaluated.Results:The results showed that the total annual BVOCs emission was estimated to be 70.8 Gg C·year^(−1),consisting 40.5%(28.7 Gg C·year^(−1))of isoprene,36.0%(25.5 Gg C·year^(−1))of monoterpenes and 23.4%(16.6 Gg C·year^(−1))of other VOCs.The emissions from Platycladus orientalis,Quercus variabilis,Populus tomentosa and Pinus tabulaeformis contributed 56.1%,41.2%,36.0% and 31.1%,respectively.The total BVOCs emission from the Jing-Jin-Ji area accounted for 61.9% and 1.8%in summer and winter,respectively.Up to 28.8% of emission was detected from Chengde followed by Beijing with 24.9%,that mainly distributed in the Taihang Mountains and the Yanshan Mountains.Additionally,the Robinia pseudoacacia,Populus tomentosa,Quercus variabilis,and Pinus tabulaeformis contributed mainly to BVOCs reaction activity.Conclusions:The BVOCs emission peaked in summer(June,July,and August)and bottomed out in winter(December,January,and February).Chengde contributed the most,followed by Beijing.Platycladus orientalis,Quercus variabilis,Populus tomentosa,Pinus tabulaeformis and Robinia pseudoacacia represent the primary contributors to BVOCs emission and atmospheric reactivity,hence the planting of these species should be reduced.

A theoretical study on the molecular structure and chemical reactivity of traditional Chinese medicine extract isopimpinellin

Isopimpinellin(C13H10O5),alternative name 5,8-dimethoxypsoralen,is one of the furocoumarin compounds.This traditional Chinese medicine extract has attracted a great deal of attention in recent years due to its pharmacological properties,especially its antifungal effect.The main purpose of this study was to study the molecular structure and chemical reactivity of isopimpinellin using the density functional theory method.To understand and interpret the reactivity of isopimpinellin,various chemical reactivity descriptors such as chemical potential(μ),electronegativity(χ),chemical hardness(η)and electrophilicity(ω)and local reactivity index condensed Fukui function(fi(r))have been calculated with five hybrid functionals PBE1PBE,MPW1PW91,B3LYP,X3LYP and B3PW91.These chemical reactivity descriptors indicate that the isopimpinellin molecule has a good antioxidant activity,which could be one of the reasons for its action as an effective antifungal drug.The condensed Fukui functions of isopimpinellin molecule provide a complete scheme of chemical reactivity of one molecule.

Modulating the Electronic Structures of Single-walled Carbon Nanotubes by Filling with Electron Acceptors and the Effect on Their Reactivity with Aryl Diazonium Salts

The electronic structures of single-walled carbon nanotubes （SWCNTs） were modulated by filling with tetracyanoquinodimethane （TCNQ）, a strong electron acceptor. The structures of TCNQ-filled SWCNTs were checked by X-ray diffraction analysis, high-resolution transmission electron microscopy and Raman spectroscopy. Optical absorption spectroscopy demonstrated an enhanced reactivity between aryl diazonium and semiconducting SWCNTs.

Comparative Theoretical Studies of the Reactivity and Stability of Selected Groups of Isomers with Carbon-Oxygen and Carbon-Nitrogen Bonds

Electronic structure calculations have been carried out to study various closely related isomers with propane backbone which form part of our quantum chemical approach to inter and intra-molecular kinetics. The usefulness of UCA-FUKUI developed by Jesús Sánchez-Márquez to facilitate the theoretical study of chemical reactivity is exploited. All isomers are identified as local minima with single-point calculations on DFT/B3LYP/6-31G(d,p). The increasing order of stability by groups of isomers are group I;propn-2-ol, propan-1-ol, group II;propanone, propanal, group III;Ethylmethanoate, Propanoic acid, Methylethanoate, group IV;N,N-dimethylformamide, propanimino, and propanamide. The trend in reactivity of the various groups of isomers and specific points of nucleophilic and electrophilic attacks are presented. We noticed that most of the properties of these isomers taught at the fundamental levels are proven true theoretically.

Cattaneo-Christov heat and mass flux model for 3D hydrodynamic flow of chemically reactive Maxwell liquid

This research focuses on the Cattaneo-Christov theory of heat and mass flux for a three-dimensional Maxwell liquid towards a moving surface. An incompressible laminar flow with variable thermal conductivity is considered. The flow generation is due to the bidirectional stretching of sheet. The combined phenomenon of heat and mass transport is accounted. The Cattaneo-Christov model of heat and mass diffusion is used to develop the expressions of energy and mass species. The first-order chemical reaction term in the mass species equation is considered. The boundary layer assumptions lead to the governing mathematical model. The homotopic simulation is adopted to visualize the results of the dimensionless flow equations. The graphs of velocities, temperature, and concentration show the effects of different arising parameters. A numerical benchmark is presented to visualize the convergent values of the computed results. The results show that the concentration and temperature fields are decayed for the Cattaneo^Christov theory of heat and mass diffusion.

MHD flow and mass transfer of chemically reactive upper convected Maxwell fluid past porous surface

The magnetohydrodynamic （MHD） flow and mass transfer of an electrically conducting upper convected Maxwell （UCM） fluid at a porous surface are studied in the presence of a chemically reactive species. The governing nonlinear partial differential equations along with the appropriate boundary conditions are transformed into nonlinear ordinary differential equations and numerically solved by the Keller-box method. The effects of various physical parameters on the flow and mass transfer characteristics are graphically presented and discussed. It is observed that the order of the chemical reaction is to increase the thickness of the diffusion boundary layer. Also, the mass transfer rate strongly depends on the Schmidt number and the reaction rate parameter. Furthermore, available results in the literature are obtained as a special case.

Permeability evolution mechanism and the optimum permeability determination of uranium leaching from low-permeability sandstone treated with low-frequency vibration

Low-frequency vibrations can effectively improve natural sandstone permeability,and higher vibration frequency is associated with larger permeability.However,the optimum permeability and permeability evolution mechanism for uranium leaching and the relationship between permeability and the change of chemical reactive rate affecting uranium leaching have not been determined.To solve the above problems,in this study,identical homogeneous sandstone samples were selected to simulate lowpermeability sandstone;a permeability evolution model considering the combined action of vibration stress,pore water pressure,water flow impact force,and chemical erosion was established;and vibration leaching experiments were performed to test the model accuracy.Both the permeability and chemical reactions were found to simultaneously restrict U6þleaching,and the vibration treatment increased the permeability,causing the U6þleaching reaction to no longer be diffusion-constrained but to be primarily controlled by the reaction rate.Changes of the model calculation parameters were further analyzed to determine the permeability evolution mechanism under the influence of vibration and chemical erosion,to prove the correctness of the mechanism according to the experimental results,and to develop a new method for determining the optimum permeability in uranium leaching.The uranium leaching was found to primarily follow a process consisting of(1)a permeability control stage,(2)achieving the optimum permeability,(3)a chemical reactive rate control stage,and(4)a channel flow stage.The resolution of these problems is of great significance for facilitating the application and promotion of lowfrequency vibration in the CO_(2)+O_(2) leaching process.

DFT Study of Dimerization Sites in Imidazo[1,2-a]pyridinyl-chalcone Series

Quantum chemistry methods were performed in order to characterize the chemical reactivity on series of imidazo[1,2-a]pyridinyl-chalcone (IPC). In particular, the B3LYP/6-311G(d) theory level has been used to determine parameters which characterize the global and local reactivity on five molecules of the series. These compounds differ from one to another with the aryl groups. There are: 1-(2-methylimidazo[1,2-a]pyridin-3-yl)-3-phenylprop-2-en-1-one, 3-(4-fluorophenyl)-1-(2-methylimidazo [1,2-a]pyridin-3-yl)prop-2-en-1-one, 3-[4-(dimethylamino)phenyl]-1-(2-methylimidazo [1,2-a]pyridin- 3-yl)prop-2-en-1-one, 3-(2,4-dichlorophenyl)-1-(2-methylimidazo [1,2-a]pyridin-3-yl)prop-2-en-1-one, 3-(2,4-dichlorophenyl)-1-(2-methylimidazo [1,2-a]pyridin-3-yl)prop-2-en-1-one. All results lead to finding out that local nucleophilicity and electrophilicity of compounds are not substituent-dependant contrarily to their global nucleophilicity which prove to be more sensitive to the electron-donating character of the substituents. 3-[4-(Dimethylamino) phenyl]-1-(2-methylimidazo[1,2-a]pyridin-3-yl)prop-2-en-1-one was identified as the unique nucleophile compound by global reactivity. Respectively, the carbon atoms C5 and C14 are the prediction sites of electrophilic and nucleophilic attacks in the molecular skeleton of both molecules. Identification of interactions centres on IPC series is of great importance for organic synthesis and medicinal chemistry where the molecular hybridization strategy is very often used to improve biological activities of interesting therapeutic systems.

Electrochemical degradation of reactive brilliant red X-3B with the(CeO_2/C)-β-PbO_2-PTFE composite electrode

The（CeO2/C）-β-PbO2-PTFE composite electrodes modified by graphite powder,cerium oxide powder,polytetrafluoroethylene（PTFE）and the homemade β-PbO2 powder were prepared by the high pressure molding technique.The X-ray diffraction（XRD）was used to test the purity of the homemade β-PbO2 powder.The surface structure and electrical property of electrodes were characterized by using scanning electron microscopy（SEM）and the cyclic voltammetry curves（CV）.Those images indicated that in electrolysis the（CeO2/C）-β-PbO2-PTFE composite electrodes had higher activity than the β-PbO2-PTFE electrodes,as good as the excellent catalytic performance.In the electrode system the composite electrodes were applied to treat reactive brilliant red（RBR）X-3B solution and we studied the degradation influence factors and the reaction mechanism.The results showed that the electrode system was well in treating RBR X-3B solution with the 20%（CeO2/C）-β-PbO2-PTFE composite electrodes at the initial 100 mg/L RBR X-3B concentration,Na2SO4 concentration of 0.35 mol/L,the constant current density of 30 mA/cm~!2 and electrolyte pH =2.After electrolytic time of 90 min,the maximum decolorization and chemical oxygen demand（COD）removal rates reached 88.92% and 54.54%.And the decolorization rate of RBR X-3B was in conformity with pseudo-first-order kinetics equation.The RBR X-3B degradation mechanism in the electrochemical oxidation system was used with LC-MS to analyze the possible intermediates and degradation pathway.

Hybrid Isothermal Model for the Ferrohydrodynamic Chemically Reactive Species

A hybrid isothermal model for the homogeneous-heterogeneous reactions in ferrohydrodynamic boundary layer ?ow is established. The characteristics of Newtonian heating and magnetic dipole in a ferro?uid due to a stretchable surface is analyzed for three chemical species. It is presumed that the isothermal cubic autocatalator kinetic gives the homogeneous reaction and the ?rst order kinetics gives the heterogeneous(surface) reaction. The analysis is carried out for equal diffusion coe?cients of all autocatalyst and reactions. Heat ?ux is examined by incorporating Fourier's law of heat conduction. Characteristics of materialized parameters on the magneto-thermomechanical coupling in the ?ow of a chemically reactive species are investigated. Further, the heat transfer rate and friction drag are depicted for the ferrohydrodynamic chemically reactive species. It is evident that the Schmidt number has increasing behavior on the rate of heat transfer in the boundary layer. Comparison with available results for speci?c cases is found an excellent agreement.

A sliding-mode triboelectric nanogenerator with chemical group grated structure by shadow mask reactive ion etching

With the support by the National Natural Science Foundation of China,a collaboration by the research groups led by Prof.Cheng Gang(程纲)from Henan University and Prof.Wang Zhonglin(王中林)from Beijing Institute of Nanoenergy and Nanosystems,Chinese Academy of Sciences,invents'a sliding-mode triboelectric nanogenerator with chemical group grated structure by shadow mask reactive ion etching',which was published in ACS Nano(2017,11(9):8796-8803).