检索结果-南通市图书馆

Green Energy & Environment 2017年第1期2卷 51-57页

作者： jacqueline González González Mónica Nájera-Lara Varinia López-Ramírez juan Antonio Ramírez-Vázquez josé j.N.Segoviano-Garfias Programa de Maestría en Biociencias División de Ciencias de la Vida (DICIVA) Universidad de Guanajuato Campus Irapuato-Salamanca Colegio del Nivel Medio Superior de Salamanca(ENMS) Departamento de Ingeniería Bioquímica Instituto Tecnológico Superior de Irapuato (ITESI) Departamento de Ciencias Ambientales División de Ciencias de la Vida (DICIVA) Universidad de Guanajuato Campus Irapuato-Salamanca

In this work, with the purpose to explore the coordination chemistry of calcium complexes which could work as a partial model of manganese-calcium cluster, a spectrophotometric study to evaluate the stability of the complexes: Calcium(Ⅱ)-1,2-ethylendiamine, Calcium(Ⅱ)-1,3-propanediamine and Calcium(Ⅱ)-1,4-butanediamine in acetonitrile, were carried on. By processing the spectrophotometric data with the HypSpec program allows the determination of the formation constants. The logarithmic values of the formation constants obtained for Calcium(Ⅱ)-1,2-ethylendiamine, Calcium(Ⅱ)-1,3-propanediamine and Calcium(Ⅱ)-1,4-butanediamine were log β_(110) = 4.69, log β_(110)= 5.25 and log β_(110) = 4.072, respectively.

关键词： Calcium(Ⅱ)complexes Solution equilibria Artificial photosynthesis Absorbance molar Speciation

Numerical Simulation of Bed Load and Suspended Load Sediment Transport Using Well-Balanced Numerical Schemes

在线全文

学校读者我要写书评

暂无评论

Communications on Applied Mathematics and Computation 2023年第2期5卷 885-922页

作者： j.C.González-Aguirre j.A.González-Vázquez j.Alavez-Ramírez R.Silva M.E.Vázquez-Cendón División Acádemica de Ciencias Básicas Universidad Juárez Autónoma de TabascoCarr.Cunduacán-Jalpa de Mendéz KM.1CP 86690CunduacánTabascoMexico Universidad Autónoma Metropolitana-Unidad Iztapalapa Av.San Rafael Atlixco no.186Mexico CityMexico Instituto de Ingeniería Universidad Nacional Autónoma de México04510 Mexico CityMexico Departamento de Matemática Aplicada Universidade de Santiago de Compostela15706 Santiago de CompostelaSpain

Sediment transport can be modelled using hydrodynamic models based on shallow water equations coupled with the sediment concentration conservation equation and the bed con-servation *** complete system of equations is made up of the energy balance law and the Exner *** numerical solution for this complete system is done in a seg-regated ***,the hyperbolic part of the system of balance laws is solved using a finite volume *** ways to compute the numerical flux have been considered,the Q-scheme of van Leer,the HLLCS approximate Riemann solver,and the last one takes into account the presence of non-conservative products in the *** discretisation of the source terms is carried out according to the numerical flux *** the second stage,the bed conservation equation is solved by using the approximation computed for the system of balance *** numerical schemes have been validated making comparisons between the obtained numerical results and the experimental data for some physical *** numerical results show a good agreement with the experimental data.

关键词： Sediment transport Suspended load Bed load Finite volume method Numerical simulation Well-balanced schemes

The nature of the companion of PSR j1719-1438: a white dwarf or an exotic object?

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2012年第7期12卷 813-816页

作者： j. E. Horvath Instituto de Astronomia Geofísica e Ciências Atmosfricas - Universidade de So Paulo

We raise the possibility that the very dense, compact companion of PSR j1719-1438, which has a jupiter-like mass, is an exotic quark object rather than a light helium or carbon white dwarf. The exotic hypothesis naturally explains some of the observed features, and provides quite strong predictions for this system, to be confirmed or refuted in feasible future studies.

关键词： binary pulsars -- exotic matter-- pulsars: individual (PSR j1719-1438)

Microstructural evaluation and nanohardness of an AlCoCuCrFeNiTi high-entropy alloy

在线全文

学校读者我要写书评

暂无评论

International journal of Minerals,Metallurgy and Materials 2019年第5期26卷 634-641页

作者： C.D.Gómez-Esparza R.Peréz-Bustamante j.M.Alvarado-Orozco j.Mu?oz-Salda?a R.Martínez-Sánchez j.M.Olivares-Ramírez A.Duarte-Moller Centro de Investigación en Materiales Avanzados (CIMAV) Laboratorio Nacional de Nanotecnología CONACYT-Corporación Mexicana de Investigación en Materiales S.A.de C.V.(COMIMSA) Centro de Ingeniería y Desarrollo Industrial Querétaro Campus Centro de Investigación y de Estudios Avanzados del IPN Unidad Querétaro Universidad Tecnológica de San juan del Río Escuela de Ingeniería Civil Industrialy Mecánica Universidad De La Salle Bajío

An AlCoCuCrFeNiTi high-entropy alloy(HEA) was prepared by mechanical alloying and sintering to study the effect of Ti addition to the widely studied AlCoCuCrFeNi system. The structural and microstructural characteristics were investigated by X-ray diffraction(XRD), scanning electron microscopy(SEM), and transmission electron microscopy(TEM). The formation of four micrometric phases was detected: a Cu-rich phase with a face-centered cubic(fcc) structure, a body-centered cubic(bcc) solid solution with Cu-rich plate-like precipitates(fcc), an ordered bcc phase, and a tetragonal structure. The XRD patterns corroborate the presence of a mixture of bcc-, fcc-, and tetragonal-structured phases. The Vickers hardness of the alloy under study was more than twice that of the AlCoCuCrFeNi alloy. Nanoindentation tests were performed to evaluate the mechanical response of the individual phases to elucidate the relationship between chemical composition, crystal structure, and mechanical performance of the multiphase microstructure of the AlCoCuCrFeNiTi HEA.

关键词： high-entropy alloys mechanical alloying microstructure nanoindentation

Effect of cerium/lanthanum addition on microstructure and mechanical properties of Al7075 alloy via mechanical alloying and sintering

在线全文

学校读者我要写书评

暂无评论

journal of Rare Earths 2016年第4期34卷 420-427页

作者： R.Pérez-Bustamante A.Reyna-Cruz D.C.Acosta-Pena C.R.Santillán-Rodríguez j.A.Matutes-Aquino F.Pérez-Bustamante M.C.Maldonado-Orozco j.Aguilar-Santillán R.Martínez-Sánchez Research Center in Advanced Materials(CIMA V) National Laboratory of NanotechnologyMiguel de Cervantes No.120C.P.31109ChihuahuaChih.Mexico Faculty of Engineering Autonomous University of Chihuahua(UACH)Circuito No.1 Nuevo Campus UniversitarioC.P.31 125ChihuahuaChih.Mexico Faculty of Chemical Sciences Autonomous University of Chihuahua(UACH)Circuito No.1 Nuevo Campus UniversitarioC.P.31125ChihuahuaChih.Mexico Materials&Tools LLC 4118 E Washington CtGilbertAZUSA 85234

The effect of the Al-6Ce-3La（ACL） on the microstructural behavior of the Al7075 was investigated. Materials were synthesized by mechanical alloying with variation in the ACL content and milling time. Products were characterized and studied in the as-milled condition and mechanically evaluated after sintering. The synergetic effect of milling time and ACL content in the modified materials led to a reduction in the particle size. Results from electron microscopy showed a homogeneous dispersion of Ce/La phases up to 20 wt.% of ACL content after 10 h of milling. Mechanical evaluation under compressive test showed an improved performance for those alloys reinforced with 0.2 wt.% and 0.5 wt.% of ACL.

关键词： mechanical alloying rare earths aluminum microstructure sintering

Computational algorithms for simulating the grain structure formed on steel billets using cellular automaton and chaos theories

在线全文

学校读者我要写书评

暂无评论

International journal of Minerals,Metallurgy and Materials 2011年第1期18卷 24-34页

作者： A.Ramírez-López G.Soto-Cortés j.González-Trejo D.Muoz-Negrón Department of Materials Metropolitan Autonomous University Institute Polytechnic National Institute Technologic Autonomous of Mexico

The development of some computational algorithms based on cellular automaton was described to simulate the structures formed during the solidification of steel *** algorithms described take results from the steel thermal behavior and heat removal previously calculated using a simulator developed by present authors in a previous *** time is used for displaying the steel transition from liquid to mushy and *** it is also used to command computational subroutines that reproduce nucleation and grain *** routines are logically programmed using the programming language C＋＋ and are based on a simultaneous solution of numerical methods （stochastic and deterministic） to create a graphical representation of different grain structures *** grain structure obtained is displayed on the computer screen using a graphical user interface （GUI）.The chaos theory and random generation numbers are included in the algorithms to simulate the heterogeneity of grain sizes and morphologies.

关键词： continuous casting solidification grain growth algorithms computer simulation

Synthesis and Crystal Structure of N-(Biphenyl-2-thiocarbamoyl)-4-(1,3-dichlorophenyl) Carboxamide

在线全文

学校读者我要写书评

暂无评论

Chinese journal of Structural Chemistry 2015年第6期34卷 853-857页

作者： AAMER SAEED ULRICH fl?RKE Department of Chemistry Quaid-I-Azam University Department Chemie Fakult?t fur Naturwissenschaften Universit?t Paderborn

The synthesis of the title molecule was achieved by the reaction of 2,4-dichloro- benzoyl chloride with potassium thiocyanate in 1：1 molar ratio in dry acetonitrile to afford the corresponding isothiocyante in situ followed by the treatment with 2-aminobiphenyl. The structure of the target compound was established by elemental analysis, FTIR, 1H, 13C NMR and mass spectroscopy and unequivocally confirmed by the crystallographic data. The title compound crystallizes in the monoclinic space group P21/n with a = 13.356（2）, b = 7.0761（11）, c = 20.539（3） A, β = 105.723（4）°, V= 1868.5（5） A3 and Z = 4.

关键词： synthesis crystal structure N-(biphenyl-2-thiocarbamoyl)-4-(1,3-dichlorophenyl) carboxamide

Synthesis and Crystal Structure of 3,5-Dichloro-N-(2-methoxyphenyl)benzamide

在线全文

学校读者我要写书评

暂无评论

Chinese journal of Structural Chemistry 2013年第2期32卷 211-214页

作者： Aamer Saeed Ulrich flrke Department of Chemistry Quaid-I-Azam University Department Chemie Fakultt fur Naturwissenschaften Universitt Paderborn

The title compound was synthesized by the direct reaction of 3,5-dichlorobenzoic acid with 2-methoxyaniline in the presence of DCC and HOBT. The structure was supported by the spectroscopic data and unambiguously confirmed by the single-crystal X-ray diffraction studies. It crystallizes from a methanol solution in the monoclinic space group P21/c with unit cell dimensions of a = 4.9369（16）, b = 13.351（5）, c = 20.168（7） A, β = 96.755（8）°, V= 1320.1（8） A^3 and Z=4.

关键词： chlorinated benzamide synthesis crystal structure

Error induced by the estimation of the corneal power and the effective lens position with a rotationally asymmetric refractive multifocal intraocular lens

在线全文

学校读者我要写书评

暂无评论

International journal of Ophthalmology(English edition) 2015年第3期8卷 501-507页

作者： David P.Piero Vicente j.Camps María L.Ramón Verónica Mateo Rafael j.Pérez-Cambrodí Grupo de óptica y Percepción Visual (GOPV).Department of Optics Pharmacology and Anatomy University of Alicante San Vicente del Raspeig Alicante 03690 Spain Department of Ophthalmology (Oftalmar) Vithas Medimar International Hospital Foundation for the Visual Quality (FUNCAVIS: Fundación para la Calidad Visual) Alicante 03016 Spain

AIM : To evaluate the prediction error in intraocular lens(IOL) power calculation for a rotationally asymmetric refractive multifocal IOL and the impact on this error of the optimization of the keratometric estimation of the corneal power and the prediction of the effective lens position(ELP).METHODS: Retrospective study including a total of 25 eyes of 13 patients(age, 50 to 83y) with previous cataract surgery with implantation of the Lentis Mplus LS-312 IOL(Oculentis Gmb H, Germany). In all cases, an adjusted IOL power(P IOLadj) was calculated based on Gaussian optics using a variable keratometric index value(n kadj) for the estimation of the corneal power(P kadj) and on a new value for ELP(ELP adj) obtained by multiple regression *** P IOLadj was compared with the IOL power implanted(P IOLReal) and the value proposed by three conventional formulas(Haigis, Hoffer Q and Holladay Ⅰ).RESULTS: P IOLReal was not significantly different than P IOLadj and Holladay IOL power(P >0.05). In the Bland and Altman analysis, P IOLadj showed lower mean difference(-0.07 D) and limits of agreement(of 1.47 and-1.61 D)when compared to P IOLReal than the IOL power value obtained with the Holladay formula. Furthermore, ELP adj was significantly lower than ELP calculated with other conventional formulas(P j. CONCLUSION: Refractive outcomes after cataract surgery with implantation of the multifocal IOL Lentis Mplus LS-312 can be optimized by minimizing thekeratometric error and by estimating ELP using a mathematical expression dependent on anatomical factors.

关键词： Mplus multifocalintraocularlens keratometry effective lens position intraocular lens power

Preparation,Characterization and Electronic Properties of fluorine-doped Tin Oxide Films

维普期刊数据库评论

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 Wuhan University of Technology(Materials Science) 2016年第1期31卷 48-51页

作者： Velázquez-Nevárez G A Vargas-García j R Lartundo-Rojas L CHEN Fei SHEN Qiang ZHANG Lianmeng Deptartment of Materials and Metallurgical Engineering National Polytechnic Institute Nanosciences and Micro and Nanotechnology Center National Polytechnic Institute State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology

Tin oxide（SnO2） and fluorine doped tin oxide（FTO） films were prepared on glass substrates by sol-gel spin-coating using SnCl4 and NH4F *** doping concentration was fixed at 4 at%and 20 at%by controlling precursor sol *** exhibited the tetragonal rutile-type crystal structure regardless of fluorine *** and highly transparent FTO films,with more than 85%of optical transmittance,were obtained by annealing at 600℃.florine doping of films was verified by analyzing the valence band region obtained by *** was found that the fluorine doping affects the shape of valence band of SnO2 *** addition,it was observed that the band gap of SnO2 is reduced as well as the Fermi level is upward shifted by the effect of fluorine doping.

关键词： tin oxide films fluorine doping energy band diagram