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Knotting ligands to control metal coordination geometry

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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 stabilization 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

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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

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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,*** GlobalWarming 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

ECHOS OF THE STEINER-lEHMUS EQUAl bISECTORSSTHEOREM

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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

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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 stability, thermal phases, energy dynamics, particle trajectories, and observable features of the black hole's shadow, as well as its oscillation frequency and decay rate.

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Morphology and phylogeny of two species of bathypathes from the tropical western Pacific,with description of a new species

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Journal of Oceanology and limnology 2025年第1期43卷 248-260页

作者： Ting lÜ Zifeng ZHAN Kuidong XU laboratory of Marine Organism Taxonomy and Phylogeny Qingdao Key Laboratory of Marine Biodiversity and ConservationInstitute of OceanologyChinese Academy of SciencesQingdao 266071China laboratory for Marine biology and biotechnology Laoshan LaboratoryQingdao 266237China University of Chinese Academy of Sciences Beijing 100049China

The black coral genus bathypathes brook,1889 represents a relatively diverse and ecologically important assemblage comprising the deep-sea hard substrate *** phylogenetic investigations have revealed the polyphyletic nature of bathypathes,urging further morphological analysis to understand its *** combing morphological and molecular data,we describe bathypathes multifurcata *** report *** Molodtsova,Opresko&Wagner,2022based on the specimens collected from the tropical western *** phylogenetic topology reconstructed using nuclear ITS1-5.8S-ITS2 and three mitochondrial fragments suggests the separation of bathypathes into four *** analysis of morphological characters,particularly the colony branch and pinnule patterns also roughly classify bathypathes into four morphological groups A–*** A is characterized by the unbranched colony and the subopposite arrangement of *** contrast to Group A,Groups b–D have the alternately arranged *** these,Group C exhibits a distinctly long unpinnulated stem compared to Groups b and *** b has unbranched colony,relatively short unpinnulated stem,and spines on pinnules have blunt *** Group D,large colonies(higher than 40 cm)have one or a few branches,small colonies(less than 40 cm)are unbranched,and spines on pinnules have acute *** data particularly those species without sequences are necessary to verify the classification of these groups.

关键词： Antipatharia black coral taxonomy phylogeny seamount western Pacific

Knotting ligands to control metal coordination geometry

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Science China Chemistry 2025年第2期 403-404页

作者： Fabien b.l.Cougnon Department of Chemistry and Nanoscience Centre University of Jyv?skyl?

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Plant-substrate biochar properties critical for mediating reductive debromination of 1,2-dibromoethane

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Journal of Environmental Sciences 2025年第1期147卷 1-10页

作者： Jonathan H.lindhardt Peter E.Holm Yong-Guan Zhu Changyong lu Hans Christian b.Hansen Department of Plant and Environmental Sciences Faculty of ScienceUniversity of CopenhagenThorvaldsensvej 401871 Frederiksberg CDenmark Key lab of Urban Environment and Health Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021China Sino-Danish Center for education and research China and DenmarkDalgas Avenue 4DK-8000 Aarhus C.Denmark

Dibromoethane is a widespread,persistent organic *** are known mediators of reductive dehalogenation by layered Fe^(Ⅱ)-Fe^(Ⅲ)hydroxides(green rust),which can reduce 1,2-dibromoethane to innocuous bromide and ***,the critical characteristics that determine mediator functionality are lesser *** biochar substrates were pyrolyzed at 600℃and 800℃,characterized by elemental analysis,X-ray photo spectrometry C and N surface speciation,X-ray powder diffraction,specific surface area analysis,and tested for mediation of reductive debromination of 1,2-dibromoethane by a green rust reductant under anoxic conditions.A statistical analysis was performed to determine the biochar properties,critical for debromination kinetics and total debromination *** was shown that selected plant based biochars can mediate debromination of 1,2-dibromoethane,that the highest first order rate constant was 0.082/hr,and the highest debromination extent was 27%in reactivity experiments with 0.1μmol(20μmol/l)1,2-dibromoethane,≈22 mmol/l Fe^(Ⅱ)GR,and 0.12 g/l soybean meal biochar(7 days).Contents of Ni,Zn,N,and P,and the relative contribution of quinone surface functional groups were significantly(ply correlated with 1,2-dibromoethane debromination,while adsorption,specific surface area,and the relative contribution of pyridinic N oxide surface groups were significantly negatively correlated with debromination.

关键词： Environmental remediation biochar Persistent organic pollutants(POPs) Environmental catalysis Green rust

Analysis of the redox environment and genesis of surface sediment in the northeast Indian Ocean at the Ninety-East Ridge

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Journal of Oceanology and limnology 2025年第1期43卷 57-72页

作者： Zhourong CAI Qianru HUANG Zhengxin YIN Xin SUI Sibo lÜ Meng TANG Juan PENG School of Marine Sciences Sun Yat-sen UniversityZhuhai 519082China Guangdong Provincial Key laboratory of Marine Resources and Coastal Engineering Zhuhai 519082China South China Sea Marine Survey Center Ministry of Natural ResourcesGuangzhou 510275China Key laboratory of Marine Environmental Survey Technology and Application Ministry of Natural ResourcesGuangzhou 510275China

The Ninety-East Ridge(NER)is located in the semioceanic to oceanic region of the southern bengal Fan in the Northeast Indian *** sedimentary environment,ocean currents,and scientific issues related to climate change have always been the focus of *** well understand the sedimentary environment of the sea area,we studied the modern sedimentary environment of the NER by analyzing the redox-sensitive trace elements(RSEs)and biomarkers in the surface sediments of the northern region and both sides of the NER and the mechanism of their *** ratios of Mo/U(average 2.22),(Cu+Mo)/Zn(average 1.51),and the results ofδCeles,all indicate the reduction of the sedimentary *** addition,the ratio of pristane(Pr)to phytane(Ph),C30diahopane to C30 hopane,and diasterane to sterane were low in all samples,on average of 1.03,0.9,and 0.33,*** analysis of RSE and biomarker data revealed that the sedimentary environment on seabed of the NER is generally a rare low-oxygen reduction *** the analysis of sediment characteristics,material sources,and ocean currents,we preliminarily constructed a genetic model for the low-oxygen reducing environment of surface sediments in the *** believe that the low-oxygen reduction environment of surface sediment in the NER could be influenced by multiple factors,such as terrestrial input of materials,productivity at sea surface,and sediment particle size.

关键词： Ninety-East Ridge(NER) surface sediment sedimentary environment redox-sensitive trace elements(RSEs) biomarker