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Helmholtz Theorems, Gauge Transformations, General Covariance and the Empirical Meaning of Gauge Conditions

Journal of Modern Physics 2016年第9期7卷 1021-1044页

作者： Andrew Chubykalo Augusto Espinoza rolando alvarado flores Unidad Academica de Fisica Universidad Autónoma de Zacatecas Zacatecas Mexico Centro de Estudios Multidisciplinarios Universidad Autónoma de Zacatecas Zacatecas México

It is well known that the use of Helmholtz decomposition theorem for static vector fields , when applied to the time dependent vector fields , which represent the electromagnetic field, allows us to obtain instantaneous-like solutions all along . For this reason, some people thought (see e.g. [1] and references therein) that the Helmholtz theorem cannot be applied to time dependent vector fields and some modification is wanted in order to get the retarded solutions. However, the use of the Helmholtz theorem for static vector fields is correct even for time dependent vector fields (see, e.g. [2]), so a relation between the solutions was required, in such a way that a retarded solution can be transformed in an instantaneous one, and conversely. On this paper we want to suggest, following most of the time the mathematical formalism of Woodside in [3], that: 1) there are many Helmholtz decompositions, all equally consistent, 2) each one is naturally related to a space-time structure, 3) when we use the Helmholtz decomposition for the electromagnetic potentials it is equivalent to a gauge transformation, 4) there is a natural methodological criterion for choosing the gauge according to the structure postulated for a global space-time, 5) the Helmholtz decomposition is the manifestation at the level of the fields that a gauge is involved. So, when we relate the retarded solution to the instantaneous one what we do is to change the gauge and the space-time. And, if the Helmholtz decompositions are related to a space-time structure, and are equivalent to gauge transformations, each gauge transformation is natural for a specific space-time. In this way, a Helmholtz decomposition for Euclidean space is equivalent to the Coulomb gauge and a Helmholtz decomposition for the Minkowski space is equivalent to the Lorenz gauge. This leads us to consider that the theories defined by different gauges may be mathematically equivalent, because they can be related by means of a gauge tra

关键词： Helmholtz Theorem Gauge Transformations Space-Time Transformations Symmetries of Differential Equations Underdetermination of Systems of Differential Equations Natural Covariance

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Nucleation and growth kinetics of La0.7Sr0.3Cr0.4Mn0.6O3-δ SOFC perovskite:Symmetry alteration evolution induced by Cu2+ and Ni2+ impregnation

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Progress in Natural Science:Materials International 2016年第6期26卷 665-670页

作者： A.Concha-Balderrama G.Rojas-George J.alvarado-flores H.Esparza-Ponce M.H.Bocanegra-Bernal A.Reyes-Rojas Centro de Investigación en Materiales Avanzados S.C.(CIMAV) Laboratorio Nacional de NanotecnologíaMiguel de Cervantes 120 Complejo Industrial ChihuahuaCd.de Chihuahua

La0.7Sr0.3Cr0.4Mn0.6O3-δperovskite nanoparticles have been synthetized using an ethylene glycol modified solgel method and impregnated by Cu0.75Ni0.25nanoparticles. The phase transitions and nucleation kinetics were studied by time resolved x-ray diffraction, Rietveld, Raman spectroscopy and high resolution transmission electron microscopy. Findings have shown that, an atomic disorder dominates from room temperature to 400 °C. Nanoparticles with crystal size < 26 nm start through nuclei formation of La0.7Sr0.3Cr0.4Mn0.6O3-δand SrCrO4solid solutions with Pm3m cubic and P21/n monoclinic symmetry respectively in the range of 600–650 °C. Symmetry reduction from the Pm3m→R3c space group had been obtained at a lower temperature（750 °C） than those reported in the literature in oxygen atmosphere and it was confirmed by an octahedral distortion, which takes place in the crystallographic direction[221]/（122）. The Johnson-Mehl-Avrami model had described the whole process, where the existence of two phases was shown before it reached its complete D3d6point group symmetry.

关键词： Perovskite structure Sol-gel method Composite Kinetics Rietveld

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Male age and strain affect ejaculate quality in the Mexican fruit fly

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Insect Science 2018年第4期25卷 703-711页

作者： Mariana Herrera-Cruz Solana Abraham Nicolas NuSez-Beverido Norma flores-Estevez Martha Reyes-Hernandez Mayvi alvarado Diana P6rez-Staples Catedra CONACYT- Facultad de Medicina y Cirugia Universidad Autonoma 'Benito Juarez' de Oaxaca Oaxaca Mexico Laboratorio de Investigaciones Ecoetologicas de Moscas de la Fruta y sus Enemigos Naturales (LIEMEN) PROIMI Tucuman Argentina CONICET Argentina INBIO TECA Universidad Veracruzana Xalapa Veracruz Mexico Instituto de Neuroetologia Universidad Veracruzana Xalapa Veracruz Mexico

Aging in all organisms is inevitable. Male age can have profound effects on mating success and female reproduction, yet relatively little is known on the effects of male age on different components of the ejaculate. Furthermore, in mass-reared insects used for the Sterile Insect Technique, there are often behavioral differences between mass-reared and wild males, while differences in the ejaculate have been less studied. The ejaculate in insects is composed mainly of sperm and accessory gland proteins. Here, we studied how male age and strain affected （i） protein quantity of testes and accessory glands, （ii） the biological activity of accessory gland products injected into females, （iii） sperm viability, and （iv） sperm quantity stored by females in wild and mass-reared Anastrepha ludens （Diptera： Tephritidae）. We found lower protein content in testes of old wild males and lower sperm viability in females mated with old wild males. Females stored more sperm when mated to young wild males than with young mass-reared males. Accessory gland injections of old or young males did not inhibit female remating. Knowledge of how male age affects different ejaculate components will aid our understanding on investment of the ejaculate and possible postcopulatory consequences on female behavior.

关键词： accessory glands age Anastrepha ludens mass-rearing sperm Tephritidae

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Effect of Using Two Different Types of Carbon Nanotubes for Blackberry (Rubus adenotrichos) in Vitro Plant Rooting, Growth and Histology

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American Journal of Plant Sciences 2014年第24期5卷 3510-3518页

作者： Dora flores Randall Chacón Luis alvarado Alexander Schmidt Carlos alvarado Juan Chaves Centro de Investigación en Biotecnología Instituto Tecnológico de Costa Rica Cartago Costa Rica Laboratorio de Nanotecnología Instituto Tecnológico de Costa Rica Cartago Costa Rica

Nanoparticles are able to interact with biomolecules, creating functional nanosystems for transportation within in vivo cells, and leading to the study of their potential applications in the field of plant biotechnology. Therefore, the aim of this research was to determine the growth and rooting effect of functionalized (SWCNTs-COOH) and non-functionalized nanoparticles with iron residue inner particles (SWCNTs-Fe) in blackberry (Rubus adenotrichos) in vitro plants. Two types of SWCNTs were used, both of them characterized in a solid sample through Raman spectroscopy (λ = 532 nm) showing differences in the G band between SWCNT + Fe and SWCNT + COOH. The in vitro plants (approximately 15 mm length) were inoculated in a rooting medium. Six treatments were established: 4, 8, 12 μg/ml for each type of SWCNTs and a control without nanotubes. The assessed variables consisted of the average number of days for root emergence, average number of roots per plant, average root length per plant and the average stem length. This study determined that, in general, the SWCNTs-COOH promoted the growth of the in vitro plants under this assay, when compared to the SWCNTs-Fe trials. The lowest SWCNTs-COOH dose evidenced the best results for the assessed variables. Additionally, the histological analysis also evidenced that the plants treated with SWCNTs-COOH nanotubes (4 μg/ml) increased their cellular metabolism when compared to the control group.

关键词： Single Walled Carbon Nanotubes Growth Rooting Blackberry TEM

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DNA Barcodes in Fig Cultivars (Ficus carica L.) Using ITS Regions of Ribosomal DNA, the psbA-trnH Spacer and the matK Coding Sequence

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American Journal of Plant Sciences 2015年第1期6卷 95-102页

作者： Carlos Castro Alejandro Hernandez Luis alvarado Dora flores Agribiotecnología de Costa Rica S.A. Alajuela Costa Rica Instituto Tecnológico de Costa Rica (ITCR) Cartago Costa Rica

Molecular markers provide a useful method for genotype characterization and allow a high precision determination of the genetic relationship between cultivars and varieties. A system based on DNA sequences—which is known as DNA barcoding—will choose one or several standard loci which can be sequenced and compared to differentiate between species. In this research, the ITS, matK, and trnH-psbA sequences were evaluated for the molecular identification of seven F. carica genotypes, generating complete sequences for the first two loci, but unable to produce bidirectional sequences by using the trnH-psbA sequence. The ITS sequence presented the highest variation rates, while the phylogeny constructed with the matK sequence obtained the highest percentage of solved monophyletic groups. Through Pearson’s correlation analysis, it was possible to determine the existence of a significant correlation between the ITS region and psbA-trnH, and the matK and psbA-trnH sequences, but not between ITS and matK. The phylogenies constructed with the ITS + matK barcodes and ITS + matK + psbA-trnH presented the highest percentage for resolution. However, considering the cost efficiency and the facilitated recovery by using PCR, the matK + ITS combination is recommended.

关键词： Ficus carica DNA Barcodes ITS psbA-trnH matK

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Atmospheric-pressure dielectric barrier discharge generation by a full-bridge flying capacitor multilevel inverter

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Plasma Science and Technology 2017年第7期19卷 40-49页

作者： Rosendo PE?A-EGUILUZ José A LóPEZ-FERNáNDEZ Antonio MERCADO-CABRERA Bethsabet JARAMILLO-SIERRA Régulo LóPEZ-CALLEJAS Benjamín RODRíGUEZ-MéNDEZ Raúl VALENCIA-alvarado Allan A flores-FUENTES Arturo E MU?OZ-CASTRO Plasma Physics Laboratory Instituto Nacional de Investigaciones Nucleares Tecnológico de Estudios Superiores de Tianguistenco Universidad Autónoma del Estado de México

A new configuration of a resonant full-bridge flying capacitor multicell inverter has been designed and constructed with the aim of achieving an extended output voltage frequency range with low harmonic distortion and reduced semiconductor commutation losses. This configuration was tested as a power supply for two different coaxial dielectric barrier discharge reactors, one of them employed for electric characterization and the other one for inorganic compound elimination in an aqueous solution. Two different gas mixtures, 90% Ar-10% 02 and 80% Ar-20% 02, were individually supplied during the experiments; the results showed a high- efficiency removal of meta-cresol （m-cresol） to the order of 98%, which was obtained by adding more oxygen to the plasma gas mixture.

关键词： plasma applications water pollution plasma sources power supply circuits electricdischarges

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Corrosion and tribocorrosion behavior of Ti6Al4V/xTiN composites for biomedical applications

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Transactions of Nonferrous Metals Society of China 2022年第2期32卷 540-558页

作者： J.CHÁVEZ O.JIMÉNEZ D.BRAVO-BARCENAS L.OLMOS F.alvarado-HERNÁNDEZ M.A.GONZÁLEZ A.BEDOLLA-JACUINDE M.flores Departamento de Ingeniería Mecánica Eléctrica CUCEIUniversidad de GuadalajaraBlvd.Marcelino García Barragán#1421GuadalajaraC.P.44430México Departamento de Ingeniería de Proyectos CUCEIUniversidad de GuadalajaraJoséGuadalupe Zuno#48Los BelenesZapopanC.P.45150México Departamento de Ingeniería de Proyectos CUCEIUniversidad de Guadalajara-CONACyTBlvd.Marcelino García Barragán#1421GuadalajaraC.P.44430México Instituto de Investigaciones en Ciencias de la Tierra INICITUniversidad Michoacana de San Nicolás de HidalgoAv.Francisco J.Mujica S/NCiudad UniversitariaMoreliaMichoacánC.P.58030México Unidad Académica de Ingeniería I Universidad Autónoma de ZacatecasAv.López Valverde 801ZacatecasZacatecasC.P.98060México Instituto de Investigaciones Metalúrgicas IIMMUniversidad Michoacana de San Nicolás de HidalgoEdificio‘‘U-5’’Ciudad UniversitariaMoreliaMichoacánC.P.58030México

The corrosion and tribocorrosion behavior of Ti6Al4V/xTiN(x=0,5,10 and 15,vol.%)composites fabricated by solid-state sintering and their relationship with the microstructure and microhardness were *** body conditions such as a temperature of 37℃ and a simulated body fluid were *** main results demonstrated a microstructural change caused by theα-Ti stabilization due to solid-solution of nitrogen(N)into the titanium(Ti)lattice,producing a maximum hardening effect up to 109%for the Ti64 matrix by using 15 vol.%*** potentials of composites changed to more noble values with the TiN particle addition,while corrosion current density of samples increased as an effect of the remaining porosity,decreasing the corrosion resistance of ***,changes to a less passive behavior were observed for samples with 15 vol.%*** non-passive behavior of composites resulted in the reduction of the potential drops during rubbing in tribocorrosion ***,an improvement of up to 88%of the wear rate of composites was seen from the solid-solution *** results allowed to understand the relationship between composition and sintering parameters with the improved tribocorrosion performance of materials.

关键词： Ti64 alloy composites powder metallurgy microstructure corrosion tribocorrosion

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Bismuth Oxide Carbonate Structures Synthesized by Microwave—Assisted Solvothermal Approach and Its Use as Catalyst for the Degradation of Azo Dye in a Solution

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Journal of Minerals and Materials Characterization and Engineering 2019年第6期7卷 468-479页

作者： M. A. Luna-alvarado M. Estrada-flores M. E. Manríquez-Ramírez C. M. Reza-San Germán Departamento de Ingeniería Química Industrial Escuela Superior de Ingeniería Química e Industrias Extractivas Instituto Politécnico Nacional Ciudad de México México

Because the textile industry wastewater is polluted with azo dyes, and in order to improve a process of wastewater remediation, the synthesized sample was evaluated in the photocatalysis of methylene blue and compared with commercial Bi2O3 and anatase TiO2. Structures of bismuth oxide carbonate (Bi2O2CO3) were successfully synthesized using a solution at 0.03 M concentration of sodium bismuthate as precursor and ethylene glycol as dissolvent by solvothermal microwave-assisted approach. The semiconductor catalyst samples were characterized by X-ray diffraction (XDR), scanning electron microscope (SEM) and Brunauer-Emmett-Teller analysis (BET). The application of the synthesized sample as catalyst, obtained a 68% of degradation. This result is better than the commercial Bi2O3 and close to the anatase TiO2 degradation. This sample shows a variation in the formula (with the presence of carbonates) but also shows an acceptable degradation percentage according to TiO2 results, making Bi2O2CO3 a possible substitute of TiO2.

关键词： Carbonate Bismuth Oxide Photocatalysis Microwave-Solvothermal Synthesis Methylene Blue Degradation

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Efficacy and long-term evaluation of intramyocardial injection of autologous CD34-enriched PBMSC in old myocardial infarction

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World Journal of Cardiovascular Diseases 2012年第4期2卷 283-290页

作者： Jose Luis Aceves Abel Archundia Araceli Paez Rafael Vilchis Elvira Varela Emma Rodriguez Guillermo Diaz Lourdes flores-Luna Martha alvarado Manuel Lopez Hernandez Luis Felipe Montano Felipe Masso Department of Cardiovascular Surgery National Medic Center 20 de Noviembre ISSSTEMexico CityMexico Department of Cellular Physiology National Institute of Cardiology“Ignacio Chavez”Mexico CityMexico Center of Population Health Research National Institute of Public HealthMexico CityMexico Department of Hematology National Medic Center 20 de Noviembre ISSSTEMexico CityMexico Immunobiology Laboratory Department of Cell and Tissue BiologySchool of Medicine UNAMMexico CityMexico

Aims: We have shown that autologous transplant of CD34+-enriched peripheral-blood mononuclear cells (PBMSC) could restore depressed myocardial function, and sustain adequate myocardial function 12 months after surgery in patients with old (>one year-old) myocardial infarction. Our aim is to report the long-term morbidity and mortality efficacy of this procedure. Methods and results: Seventy patients with an old anteroseptal myocardial infarction were followed for 2 to 7 years, 35 had a revascularization procedure and received an intra-myocardial injection of autologous CD34+-enriched PBMSC (8 × 108 mononuclear cells/ml including 3 × 107 CD34+ cells/ml)(Group A). Group B patients only had the revascularization. Abnormal pre-surgical values of LVEF (33.2% ± 4.8%), LVDV (178 ± 13.7 ml), LVSV (120 ± 16 m), LVDD (58.9 ± 3.84 mm), E and A waves without contractility in infarction area in group A patients improved to approximate normal values (50% ± 3% for LVEF;90 ± 9.3 ml for LVDV;80 ± 9.9 ml for LVSV;55.3 ± 3 mm for LVDD;5.2 ± 0.5 cm/s for E wave and 4.18 ± 0.3 cm/s for A wave) 1 year after the procedure and have remained unaltered for all the follow-up period. All the patients remain alive. Only seven patients have been readmitted to the hospital for non-myocardial related events. Group B only 11 patients continued alive to 5 years after surgery and LEVF never increased more than 6%, all of them with many hospitalizations (n ≥ 10) by heart failure events. Conclusion: Intramyocardial injection of CD34+ highly enriched PBSC represent an encouraging alternative for patients with severely scarred and dysfunctional myocardium.

关键词： Stem Cells Myocardial Infarction CD34+ Cells Revascularization Heart Failure Ventricular Function

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Microstructural evaluation and nanohardness of an AlCoCuCrFeNiTi high-entropy alloy

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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

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