检索结果-南通市图书馆

Knotting ligands to control metal coordination geometry

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2025年第2期68卷 403-404页

作者： Fabien b.l.Cougnon Department of Chemistry and Nanoscience Centre University of JyväskyläJyväskyläFinland

Zinc is a metal of particular importance for life[1].It is the most abundant transition metal in biological systems after iron and contributes both structural and catalytic roles to many cellular *** properties of Zn^(Ⅱ),unlike those of any other first-row transition metal ions,explain its biological *** to its filled d-shell orbitals,Zn^(Ⅱ) is redox-stable,has a ligand-field energy stab.l.zation of zero and,consequently,no typical coordination number and *** metalloproteins exploit these features to carry a broad range of chemical reactions in mild *** metalloenzymes,unsaturated ZnII centres often act as redox-stable lewis *** protein backbone provides a highly preorganized environment around the metal centre and accompanies the changes in coordination geometry occurring as substrate transformation proceeds,thereby modulating the metal reactivity.

关键词： coordination geometry centre

Atmospheric chemistry of trifluorodicarbonyls initiated by Cl atoms:Reactivity trends,mechanism,and acid formation yields

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2025年第5期151卷 12-25页

作者： Pedro l.lugo Vianni G.Straccia Cynthia b.Rivela Mariano A.Teruel María b.blanco laboratorio Universitario de Química y Contaminación del Aire(l.U.Q.C.A) Instituto de Investigaciones en Fisicoquímica de Córdoba(I.N.F.I.Q.C.)Dpto.de Fisicoquímica.Facultad de Ciencias QuímicasUniversidad Nacional de Córdoba.Ciudad Universitaria5000 CórdobaArgentina Institute for Atmospheric and Environmental Research University of WuppertalDE-42097 WuppertalGermany

Rate coefficients of the gas-phase reactions of Cl atoms with a series of fluorinated diketones(FDKs):CF_(3)C(O)CH_(2)C(O)CH_(3)(TFP),CF_(3)C(O)CH_(2)C(O)CH_(2)CH_(3)(TFH)and CF_(3)C(O)CH_(2)C(O)CH(CH_(3))2(TFMH),have been measured at(298±2)K and under atmospheric *** experiments were performed using the relative-rate method with a GC-FID detection *** different determinations and references used,the following rate coefficients were obtained(in cm3/(molecule·sec)):k_(4)(TFP+Cl)=(1.75±0.21)×10^(−10),k_(5)(TFH+Cl)=(2.05±0.23)×10^(−10),k_(6)(TFMH+Cl)=(2.71±0.34)×10^(−10).Reactivity trends of FDKs were discussed and Free Energy Relationships analysis was *** expression lgkOH=1.68 lgkCl+5.71 was obtained for the reactivity of the studied FDKs together with similar unsaturated VOCs with Cl and OH radicals Additionally,acetic acid(CH_(3)C(O)OH)and trifluoroacetic acid(CF_(3)C(O)OH)were positively identified and quantified as degradation products using in situ FTIR *** to the identified products,atmospheric chemical mechanisms were *** atmospheric implications of the studied reactions were assessed by the estimation of the tropospheric lifetimes of TFP,TFH,and TFMH concerning their reaction with Cl atoms to be 48,41,and 31 hours,*** relatively short residence in the atmosphere of the fluorocarbons studied will have a local/regional impact with restricted *** warming potential(GWP(20 yr))calculated for the studied fluoro diketones were 0.014,0.003 and 0.001 for TFP,TFH and TFMH,respectively with a negligible contribution to the greenhouse effect.

关键词： Fluorinated diketones Kinetics SPME-GC-FID FTIR in situ SAR Free energy relationships

Kinetics of the reaction of OH radical with ethylfluoroacetate,ethyl 4,4,4-trifluorobutyrate,and butylfluoroacetate

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2025年第5期151卷 273-283页

作者： Pedro l.lugo Vianni Straccia Mariano A.Teruel María b.blanco laboratorio Universitario de Química y Contaminación del Aire(l.U.Q.C.A) Institute for Research in Physical Chemistry of Córdoba(I.N.F.I.Q.C.)Department of Physical ChemistryFaculty of Chemical SciencesNational University of CórdobaUniversity CityCórdoba 5000Argentina Institute for Atmospheric and Environmental Research University of WuppertalWuppertal DE-42097Germany

Kinetics of the gas-phase reactions of•OH radicals with a series of fluoroesters were studied for the first time at 298±3 K and atmospheric *** rate coefficients were determined by in situ FTIR spectroscopy in nitrogen and GC-FID in air to monitor the decay of reactants and *** following coefficient values(in 10^(−12)cm^(3)/(molecule•sec))were obtained for ethyl fluoroacetate(EFA),ethyl 4,4,4-trifluorobutyrate(ETb),and butyl fluoroacetate(bFA),respectively:k_(1)(EFA+OH)=1.15±0.25 by FTIR and 1.34±0.23 by GC-FID;k_(2)(ETb+OH)=1.61±0.36 by FTIR and 2.02±0.30 by GC-FID;k_(3)(bFA+OH)=2.24±0.37 by *** trends were developed and correlated with the number of CH_(3)and F substituents in the fluoroester,and structure-activity relationships(SARs)calculations were *** addition,the tropospheric lifetimes of EFA,ETb,and bFA upon degradation by OH radicals were calculated to be 9,6,and 5 days,respectively,indicating that these fluorinated compounds could have a possible regional effect from the emission *** small photochemical ozone creation potentials of 9,7,and 19 were estimated for EFA,ETb,and bFA,*** Glob.l.arming Potentials(GWPs)for EFA,ETb,and bFA were calculated for different time *** a 20-year time horizon,the GWPs were 1.393,0.063,and 0.062,*** the case of a 100-year time horizon,the GWPs were 0.379,0.017,and 0.017,and for a 500-year time horizon,the GWPs were 0.108,0.005,and 0.005 for EFA,ETb,and bFA.

关键词： CFC replacements sinks in situ FTIR SAR Acidification potentials Greenhouse gases

Pro-resolving lipid mediator reduces amyloid-β42–induced gene expression in human monocyte–derived microglia

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Neural Regeneration Research 2025年第3期20卷 873-886页

作者： Ying Wang Xiang Zhang Henrik biverstål Nicolas Gbazan Shuai Tan Nailin li Makiko Ohshima Marianne Schultzberg Xiaofei li Department of Neurobiology Care Sciences&SocietyDivision of NeurogeriatricsKarolinska InstitutetStockholmSweden Department of Neurology Neuroscience CenterThe First Hospital of Jilin UniversityChangchunJilin ProvinceChina Department of Physiology and Pharmacology Karolinska InstitutetStockholmSweden Department of biosciences and Nutrition Karolinska InstitutetHuddingeSweden Neuroscience Center of Excellence Louisiana State UniversityNew OrleansLAUSA Department of Medicine SolnaClinical Pharmacology GroupKarolinska University HospitalStockholmSweden

Specialized pro-resolving lipid mediators including maresin 1 mediate resolution but the levels of these are reduced in Alzheimer's disease brain, suggesting that they constitute a novel target for the treatment of Alzheimer's disease to prevent/stop inflammation and combat disease pathology. Therefore, it is important to clarify whether they counteract the expression of genes and proteins induced by amyloid-β. With this objective, we analyzed the relevance of human monocyte–derived microglia for in vitro modeling of neuroinflammation and its resolution in the context of Alzheimer's disease and investigated the pro-resolving bioactivity of maresin 1 on amyloid-β42–induced Alzheimer's disease–like inflammation. Analysis of RNA-sequencing data and secreted proteins in supernatants from the monocyte-derived microglia showed that the monocyte-derived microglia resembled Alzheimer's disease–like neuroinflammation in human brain microglia after incubation with amyloid-β42. Maresin 1 restored homeostasis by down-regulating inflammatory pathway related gene expression induced by amyloid-β42 in monocyte-derived microglia, protection of maresin 1 against the effects of amyloid-β42 is mediated by a re-b.l.ncing of inflammatory transcriptional networks in which modulation of gene transcription in the nuclear factor-kappa b pathway plays a major part. We pinpointed molecular targets that are associated with both neuroinflammation in Alzheimer's disease and therapeutic targets by maresin 1. In conclusion, monocyte-derived microglia represent a relevant in vitro microglial model for studies on Alzheimer's disease-like inflammation and drug response for individual patients. Maresin 1 ameliorates amyloid-β42–induced changes in several genes of importance in Alzheimer's disease, highlighting its potential as a therapeutic target for Alzheimer's disease.

关键词： Alzheimer's disease amyloid-β maresin microglia monocyte neuroinflammation resolution RNA-sequencing specialized pro-resolving lipid mediator

ECHOS OF THE STEINER-lEHMUS EQUAl bISECTORSSTHEOREM

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2025年第1期45卷 257-263页

作者： Christoph bÖRGERS Eric l.GRINbERG Mehmet ORHON Junhao SHEN Department of Mathematics Tufts UniversityMedfordMA02155USA Department of Mathematics University of Massachusetts BostonBostonMA02125USA Department of Mathematics&Statistics University of New HampshireDurhamNH03824USA

The Steiner-lehmus equal bisectors theorem originated in the mid 19th *** its age,it would have been accessible to Euclid and his *** theorem remains evergreen,with new proofs continuing to appear *** theorem has fostered discussion about the nature of proof itself,direct and *** we continue the momentum by providing a trigonometric proof,relatively short,based on an analytic estimate that leverages algebraic trigonometric *** proofs of the theorem exist in the *** of these contain key ideas that already appeared in ***’1850 proofs,not always with *** the aim of increasing awareness of and making more accessible lehmus’proofs,we provide an annotated *** conclude with remarks on different proofs and relations among them.

关键词： Steiner-lehmus theorem equal bisectors

Schwarzschild black hole surrounded by a cloud of strings in the background of perfect fluid dark matter

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2025年第02期 224-240页

作者： b.Hamil b.C.lütfüo?lu laboratoire de Physique Mathématique et Subatomique Faculté des Sciences ExactesUniversité Constantine 1 Department of Physics Faculty of ScienceUniversity of Hradec Kralove

This manuscript investigates a Schwarzschild black hole surrounded by perfect fluid dark matter embedded in a cloud of strings. The effects of its surroundings on thermodynamics, timelike and null geodesics, shadows,and quasinormal modes are analyzed. It is demonstrated that changes in spacetime, induced by the surrounding environment, significantly influence the stab.l.ty, thermal phases, energy dynamics, particle trajectories, and observable features of the black hole's shadow, as well as its oscillation frequency and decay rate.

关键词：

Computational Insights into the Interactions of Farnesoid X Receptor with Fargesone A,a Natural Product from Magnolia fargesii

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2025年第1期41卷 146-154页

作者： ZHANG li CHEN Yaqiong li Weihua School of Pharmacy Shanghai Key Laboratory of Molecular ImagingShanghai University of Medicine and Health SciencesShanghai201318P.R.China School of Pharmacy East China University of Science and TechnologyShanghai200237P.R.China

Farnesoid X receptor(FXR)is a ligand-activated nuclear receptor and plays important roles in the regulation of metab.l.sm and homeostasis of several important physiological substances,such as b.l. acids,glucose,and *** such,FXR has become a promising therapeutic target for the treatment of several metab.l.c diseases and liver ***,fargesone A(FA),a natural product from Magnolia fargesii was identified to be a novel,potent FXR agonist that demonstrated good in vitro and in vivo ***,the detailed interaction mechanism of FA with FXR remains *** this study,we employed multiple computational approaches including molecular docking,molecular dynamics simulation,and binding free energy calculation to address the *** comparisons of the structural dynamics and binding free energies,an optimal binding mode was identified,in which FA interacts with FXR via a direct hydrogen bond with His447 and hydrophobic interactions with multiple residues,such as leu287,Met290,Met328,Ile352,and *** mutants,namely,H447F and l287N,were further constructed to validate the importance of the identified *** anticipate that these findings could be helpful for future rational design of new FA analogues targeting FXR.

关键词： Farnesoid X receptor(FXR) binding mode Molecular docking Molecular dynamics Fargesone A

Constraints on holographic QCD phase transitions from PTA observations

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2025年第1期68卷 67-74页

作者： Song He li li Sai Wang Shao-Jiang Wang Center for Theoretical Physics and College of Physics Jilin UniversityChangchun 130012China School of Physical Science and Technology Ningbo UniversityNingbo 315211China CAS Key laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of Sciences(UCAS)Hangzhou 310024China Theoretical Physics Division Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China School of Physical Sciences University of Chinese Academy of Sciences(UCAS)Beijing 100049China Max Planck Institute for Gravitational Physics(Albert Einstein Institute) Am Muhlenberg 1Golm 14476Germany

The underlying physics of QCD phase transition in the early Universe remains largely unknown due to its strong-coupling nature during the quark-gluon plasma/hadron gas transition,yet a holographic model has been proposed to quantitatively fit the lattice QCD data while with its duration of the first-order phase transition(FoPT)left *** specific baryon chemical poten-tial,the first-order QCD phase transition agrees with the observational constraint of baryon ***,therefore,provides a scenario for phase transition gravitational waves(GWs)within the standard model of particle *** these background GWs could contribute dominantly to the recently claimed common-spectrum red noise from pulsar timing array(PTA)observations,the duration of this FoPT can be well constrained,and the associated primordial black holes are still allowed by current observations.

关键词： pulsar timing array QCD phase transition gravitational waves primordial black holes

Controllable chaos in the coupled waveguide-optomechanical system with phase shifter

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2025年第04期Mechanics & Astronomy) .卷 30-38页

作者： Deng-Wei Zhang Pei-Qi Qin li-li Zheng Zhi-Ming Zhan Xin-You lü Department of Mathematics and Physics Luoyang Institute of Science and Technology School of Computer and Information Engineering School of Software Luoyang Institute of Science and Technology School of Artificial Intelligence Jianghan University School of Physics Huazhong University of Science and Technology

We theoretically investigate chaotic dynamics in an optomechanical system composed of a whispering-gallery-mode(WGM) microresonator and a sensor. We find that tuning the optical phase using a phase shifter and modifying the coupling strength via a unidirectional waveguide(IWG) can induce chaotic motion. The underlying reason for this phenomenon is that adjusting the phase and coupling strength via the phase shifter and IWG bring the system close to an exceptional point(EP), where field localization dynamically enhances the optomechanical nonlinearity, leading to the generation of chaotic motion. In addition, due to the sensitivity of chaos to phase in the vicinity of the EP, we propose a theoretical scheme to measure the optical phase perturbations using chaos. Our work may offer an alternative approach to chaos generation with current experimental technology and provide theoretical guidance for optical signal processing and chaotic secure communication.

关键词：