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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 l.b.ratorio 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 l.b.ratorio 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,*** Gl.b.lWarming 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.b.SECTORSSTHEOREM

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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.b.sectors 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.b.sectors

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 l.b.ratoire 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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Green disposal of waste smartphone protective film:Efficiency,mechanism,bench-scale test and secondary waste reutilization

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Journal of Environmental Sciences 2025年第5期151卷 692-702页

作者： Jiangyao chen Shunyu Ding chenxu Gao Canhui chen Taicheng An Guangdong Key l.b.ratory of Environmental Catalysis and Health Risk Control Guangdong Technology Research Center for Photocatalytic Technology Integration and Equipment EngineeringInstitute of Environmental Health and Pollution ControlGuangdong University of TechnologyGuangzhou 510006China Guangzhou Key l.b.ratory of Environmental Catalysis and Pollution Control Guangdong-Hong Kong-Macao Joint Laboratory for Contaminants Exposure and HealthSchool of Environmental Science and EngineeringGuangdong University of TechnologyGuangzhou 510006China

The manufacture and obsolescence of smartphones produce numerous waste plastic accessories(e.g.,waste smartphone protective film(WSPF)),possessing immense potential for ***,avail.b.e recycling technologies have limitations such as substrate damage and secondary pollutant *** present study aimed to develop a green disposal method that not only recycled polyethylene terephthalate(PET)from WSPF,but also reused the stripped polyacrylate(PAA)adhesive as an adsorbent to reduce solid waste *** the WSPF was treated in 1 mol/l NaOH solution at 90°C,the PAA hydrolyzed to two main by-products of 1-butanol and 2-ethylhexanol,weakening the binding strength between PAA and PET and then efficient separation of *** bench-scale test revealed that over 97.2%of detachment efficiency toward PAA was achieved during continuous treatment of 17 batches of WSPF(200 g for each)without supplement of NaOH and generation of ***,the economic evaluation indicated that the recycling method would generate a net profit margin of 647%for the second year without considering the incurrence of new cost and ***,the pyrolysis of waste PAA enabled its conversion into potential adsorbent,which showed 2 to 4 times enhanced adsorption capacity toward styrene and ethyl acetate after modification with NaOH *** study provides a green method for recycling waste plastics and inspires a referable solution for solid waste treatment in the smartphone industry.

关键词： Smartphone accessory Waste protective film Green recycle Polyethylene terephthalate Polyacrylate Adsorbent

Multiple-event-triggered adaptive fuzzy output-feedback control for MIMO uncertain nonlinear systems

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Science China(Technological Sciences) 2025年第2期68卷 216-226页

作者： Shuai SUI Yu YANG Shaocheng TONG C.l.Philip chen School of Science Liaoning University of TechnologyJinzhou 121001China School of Computer Science and Engineering South China University of TechnologyGuangzhou 510006China

The article addresses the output-feedback control issue for a class of multi-input multi-output(MIMO)uncertain nonlinear systems with multiple event-triggered mechanisms(ETM).Compared to previous event-triggering studies,this paper aims to trigger both the output and filtered *** nonlinear dynamics are approximated using fuzzy logic systems(FlSs).Then,a novel kind of state observer has been designed to deal with unmeasurable state problems using the triggered output *** sampled estimated state,the triggered output signal,and the filtered signal are utilized to propose an event-triggering mechanism that consists of sensor-to-observer(SO)and observer-to-controller(OC).An event-triggered output feedback control approach is given inside backstepping control,whereby the filter may be employed to circumvent the issue of the virtual control function not being differentiable at the trigger *** is testified that,according to the lyapunov stability analysis scheme,all closed-loop signals and the system output are ultimately uniformly constrained by our control ***,the simulation examples are performed to confirm the theoretical findings.

关键词： event-triggered control(ETC) dynamic surface control(DSC) output-feedback control fuzzy adaptive control

On-line determination of selenium compounds in tea infusion by extractive electrospray ionization mass spectrometry combined with a heating reaction device

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Chinese Chemical letters 2025年第1期36卷 496-500页

作者： lu Huang Jiang Wang Hong Jiang lanfang chen Huanwen chen Academician Workstation Jiangxi University of Chinese MedicineNanchang 330004China Suzhou Jingcheng Precision Instrument Technology Co. Ltd.Suzhou 215228China The First Affiliated Hospital of Nanchang University Nanchang 330006China

Selenium is one of the important trace elements in the human *** deficiency will directly affect human *** people's attention to health,the content of selenium in food has gradually attracted ***,detecting selenium compounds in complex samples remains a *** this work,we built an online heating-reaction *** device combines the electrospray extraction ionization mass spectrometry(EESI-MS)with the heating reaction device,which can simultaneously detect various selenium compounds in complex liquid *** acidic conditions,the sample was heated and catalyzed by a heating reaction device,so that the SeO~(2-)_(3)and O-phenylenediamine(OPD)could generate 1,3-dihydro-2,1,*** on the above reactions,we can detect organic selenium,inorganic selenium and other compounds in liquid samples by organic mass *** this experiment,we determined the content of three forms of selenium:selenomethionine(SeMet),l-selenocystine(SeCys(2)),and sodium *** cal.b.ation curves for SeMet,SeCys(2),and sodium selenite showed strong linearity within a range of 0.50-50.00μg/*** limits of detection(lOD)for the three compounds were 0.22,0.27,and 0.41μg/l,*** limits of quantification(lOQ)were 0.68,0.81,and 1.23μg/l,*** recoveries at three levels ranged from 98.8%to 106.1%.In addition,this method can simultaneously detect three selenium compounds and three other specific chemical components in tea infusion samples,providing a rapid and efficient method for identifying tea quality.

关键词： Heating reaction device Extractive electrospray ionization mass spectrometry Inorganic selenium Selenium compounds Tea infusion

New Taub-NUT black holes with massive spin-2 hair

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Science China(Physics,Mechanics & Astronomy) 2025年第2期68卷 51-58页

作者： Yu-Qi chen Hai-Shan liu Center for Joint Quantum Studies and Department of Physics School of ScienceTianjin UniversityTianjin 300350China

We consider Einstein gravity extended with quadratic curvature invariants,within which the well-known Ricci-flat Taub-NUT black hole remains a *** analysis of the unstable lichnerowicz modes in the Taub-NUT background enables us to identify the mass and NUT parameters(m,n)where new Taub-NUT black holes can *** then adopt numerical techniques to construct these new Taub-NUT black holes,which bifurcate away from the Ricci-flat *** the Ricci-flat Taub-NUT,there can exist two new black holes for an appropriate given temperature,making it a total of three if we include the Ricci-flat one.

关键词： higher derivative gravity black hole solution Taub-NUT spacetime