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International Journal of Analytical Mass Spectrometry and Chromatography 2019年第2期7卷 19-34页

作者： Belén Gastaca Hernán Rubén Sánchez Fiorella Menestrina maricel Caputo maría de las mercedes schiavoni Jorge Javier Pedro Furlong Laboratory of Organic Compounds Studies (LAdeCOR) Department of Chemistry Facultad de Ciencias Exactas National University of La Plata La Plata Argentina Institute of Physics of Liquids and Biological Systems (IFLySIB CONICET) National University of La Plata La Plata Argentina Laboratory of Research and development of Analytical Methods (LIDMA) Department of Chemistry Facultad de Ciencias Exactas National University of La Plata La Plata Argentina

Tautomeric forms of Thiosemicarbazones have been investigated by spectrometric methods, their chemical reactivity and theoretical calculations of the relative tautomers stabilities. The mass spectral fragmentation of thiosemicarbazones synthesized from acetophenones has been studied by CG/MS. The analysis of the corresponding spectra shows not only the regular fragmentation mechanisms but homolytic ruptures from even-electron species. 1H NMR spectra exhibit signals for the most intense open thioketo tautomeric structure, although when using TFA a ring structure is observed in the corresponding tautomeric equilibrium. density Functional Theory calculations (DFT) also provide evidence to support the experimental observations by GC-MS and 1H NMR. Methylation reactions give support to the occurrence of the thioenol tautomeric form which would be the second most abundant according to the density Functional Theoretical calculations.

关键词： Thiosemicarbazones Tautomerism MS NMR Theoretical Calculations

GC/MS Analyses of Thiosemicarbazones Synthesized from Acetophenones: Thermal decay and Mass Spectra Features

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International Journal of Analytical Mass Spectrometry and Chromatography 2015年第1期3卷 1-13页

作者： Belén Gastaca Gastón Galletti Hernán Rubén Sánchez Reinaldo Pis Diez maría de las mercedes schiavoni Jorge Javier Pedro Furlong Laboratorio de Estudio de Compuestos Orgánicos (LAdeCOR) Departamento de Química Facultad de Ciencias Exactas Universidad Nacional de La Plata La Plata Argentina CEQUINOR Centro de Química Inorgánica (CONICET UNLP) Facultad de Ciencias Exactas UNLP La Plata Argentina

The mass spectral fragmentation of thiosemicarbazones synthesized from acetophenones has been studied by CG/MS. These carbonyl compounds exhibit chromatographic peaks which are not observed in aliphatic analogues or those synthesized from aldehydes. The analysis of the corresponding spectra has allowed structural assignment to the dimerization of gas phase neutral fragments. Theoretical calculations (DFT level) also provide evidence to support the experimental observations.

关键词： Thiosemicarbazones Mass Spectrometry Analyses Dimerization of Thiosemicarbazones

Multitasking Behavior and Perceptions of Academic Performance in University Business Students in Mexico during the COVID-19 Pandemic

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International Journal of Mental Health Promotion 2022年第4期24卷 565-581页

作者： Victoria Gonzáles-Gutierrez Aldo Alvarez-Risco Alfredo Estrada-Merino maría de las mercedes Anderson-Seminario Sabina Mlodzianowska Shyla del-Aguila-Arcentales Jaime A.Yáñez CETYS Universidad MexicaliBaja CaliforniaMexico Universidad de Lima Facultad de Ciencias Empresariales y EconómicasCarrera de Negocios InternacionalesLimaPeru Escuela Nacional de marina Mercante“Almirante Miguel Grau” CallaoPeru Universidad Norbert Wiener Vicerrectorado de InvestigaciónLimaPeru Teoma Global Gerencia Corporativa de Asuntos Científicos y RegulatoriosLimaPeru

The current study measures the inﬂuence of multitasking behavior and self-efﬁcacy for self-regulated learning(SESRL)on perceptions of academic performance and views in university students during the COVID-19 pan-demic in Mexico.264 university students fulﬁlled an online *** was observed that multitasking beha-vior negatively inﬂuences SESRL(-0.203),while SESRL showed a positive inﬂuence of 0.537 on perceptions of academic performance,and multitasking behavior had an inﬂuence of-0.097 on the perception of academic ***’s alpha and Average Variance Extracted values were 0.809 and 0.577(multitasking behavior),0.819 and 0.626(SESRL),0.873 and 0.725(perceptions of academic performance),*** results of the bootstrapping test showed that the path coefﬁcients were signiﬁ*** study outcomes can support new plans in universities to ensure the best academic *** study showed evidence of the COVID-19 impact on education *** study’s novelty is based on using the partial least square structural equation modeling(PLS-SEM)technique to evaluate these variables.

关键词： Multitasking behavior COVID-19 Mexico self-efﬁcacy for self-regulated learning academic performance online class pandemic Peru

The Conditional Heterocedasticity on the Argentine Inflation. An Analysis for the Period from 1943 to 2013

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Journal of Mathematics and System Science 2017年第10期7卷 269-277页

作者： Juan Carlos Abril maria de las mercedes Abril Universidad Nacional de Tucumcin Facultad de Ciencias Economicas and Consejo Nacional de lnvestigaciones Cientificas y Tecnicas (CONICET). Tucuman. Argentina.

Numerous economic time series do not have a constant mean and in practical situations, we often see that the variance of observational error is subject to a substantial variability over time. This phenomenon is known as volatility. To take into account the presence of volatility in an economic series, it is necessary to resort to models known as conditional heteroscedastic models. In these models, the variance of a series at a given time point depends on past information and other data available up to that time point, so that a conditional variance must be defined, which is not constant and does not coincides with the overall variance of the observed series. There is a very large variety of nonlinear models in the literature, which are useful for the analysis of any economic time series with volatility, but we will focus in analyzing our series of interest using ARCH type models introduced by Engle （1982） and their extensions. These models are non-linear in terms of variance. Our objective will be the study of the monthly inflation data of Argentina for the period from January 1943 to december 2013. The data is officially published by the National Institute of Statistics and Censuses （or INdeC as it is known in Argentina）. Although it is a very long period in which various changes and interventions took place, it can be seen that certain general patterns of behavior have persisted over time, which allows us to admit that the study can be appropriately based on available information.

关键词： Inflation heterocedasticity volatility time series.

Mixtures of Distributions and Volatility

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Journal of Statistical Science and Application 2016年第4期4卷 179-189页

作者： Juan Carlos Abril maria de las mercedes Abril Carlos Ismael martinez Universidad Nacional de Tucuman. Facultad de Ciencias Economicas and Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET). Tucuman. Argentina.

Using Monte Carlo methods we generate time series with the following features： a） series with distributions that are the mix of two normal distributions with different variances, b） series that satisfy volatility models, c） series that satisfy an AR（1） model but with contaminated errors that follow the same distribution as the mixes given in a） and d） series that follow the same distribution as the mixes given in a） but with conditional heterocedasticity. From the analysis we see that it is difficult to identify in practical situations the real generating process of the series. In fact, the processes that come from distribution mixes have many similar characteristics to the ones that satisfy the volatility scheme. We use the corresponding theoretical considerations and also the usual tools in the identifying process of any time series; that is, series graphs, histograms, the corresponding sampling distributions, correlograms and partial correlograms.

关键词： Autoregression Contaminated errors Distribution mixes AR(1) models ARCH models Volatility.

The Multivariate Saddlepoint Approximation to the Distribution of Estimators： A General Approach

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Journal of Mathematics and System Science 2016年第2期6卷 53-59页

作者： Juan Carlos Abril maria de las mercedes Abril Carlos I. martinez Universidad Nacional de Tucum6n and Consejo Nacional de lnvestigaciones Cientifieas y Técnicas (CONICET). Tucumán Argentina.

We develop the theory of multivariate saddlepoint approximations. Our treatment differs from the one in Barndorff-Nielsen and Cox （1979, equation （4.7）） in two aspects： 1） our results are satisfied for random vectors that are not necessarily sums of independent and identically distributed random vectors, and 2） we consider that the sample is taken from any distribution, not necessarily a member of the exponential family of densities. We also show the relationship with the corresponding multivariate Edgeworth approximations whose general treatment was developed by Durbin in 1980, emphasizing that the basic assumptions that support the validity of both approaches are essentially similar.

关键词： Approximate distributions Asymptotic expansions Edgeworth approximations Saddlepoint approximations.

Dramatic Improvement in Physical Well-Being of Terminal AIDS Patients Following Administration of Phytochemicals

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World Journal of AIDS 2013年第3期3卷 287-291页

作者： maria de las mercedes Lavandera Díaz Felix Antonio Cruz Jiminian Ruben Wernik Walter Franklin Goldman Gadi Borkow Immune Nutrition Incorporation Rehovot Israel.

Phytochemicals (PHT) are biologically active chemicals produced by plants, non-essential nutrients, with medicinal properties. In this short communication we report the dramatic improvement in the physical and clinical well-being of 9 terminal AIDS patients that received Phyto V7, a PHT mix, for a period of 3 months. All patients living in the Dr. Cruz Jiminian Foundation (hospice) in Santo Domingo, Dominican Republic, were in an emaciated condition—most could not eat, sit down, shower, stand up or dress alone;all had high viremia (from ~50,000 to above 500,000;243,816 ± 176,724 HIV-1 RNA copies/ml) and very low CD4+ T-cells counts (142 ± 51 counts/mm3). The clinical status of all patients was C3 according to the United States Centers for Disease Control (CDC) status index. As antiretroviral treatment was not available to the Foundation at the time of the study, the only treatment that they received was Phyto V7 supplementation. Each individual received 5 tablets 3 times a day, each tablet containing 750 mg of Phyto V7. At the end of the 3 months, Phyto V7 supplementation radically improved the well-being of all 9 patients. All patients could eat, sit down, shower, stand up and dress alone. This study supports the notion that PHT supplementation can improve significantly the well-being of terminally ill AIDS patients and is the foundation to conducting further control studies to substantiate this notion.

关键词： Phytochemicals HIV-1 AIDS

Pennsylvanian glacimarine sedimentation in the Cushamen Formation,western North Patagonian Massif

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Geoscience Frontiers 2018年第2期9卷 485-504页

作者： Paulo marcos Daniel A.Gregori Leonardo Benedini mercedes Barros Leonardo Strazzere Cecilia Pavón Pivetta Cátedra de Geofísica Departamento de GeologíaUniversidad Nacional del Sur and INGEOSURSan Juan 6708000 Bahía BlancaArgentina Cátedra de Geología Argentina Departamento de GeologíaUniversidad Nacional del Sur and INGEOSURSan Juan 6708000 Bahía BlancaArgentina Cátedra de Geología Minera Departamento de GeologíaUniversidad Nacional del Sur and INGEOSURSan Juan 6708000 Bahía BlancaArgentina

The metasedimentary sequence of the Cushamen Formation in the western North Patagonian Massif is540 m thick and comprises six sedimentary lithofacies associations related to a glacimarine *** of these lithofacies represent distal glacimarine environments, whereas another one was deposited in proximal glacimarine environments, and the last includes subglacial environments. The organization and configuration of these lithofacies associations represent the advance and retreat of the glacier masses. The maximum glacial advance is correlatable with the G2 glacial interval of the Pennsylvanian Pampa de Tepuel, las Salinas and Valley Chico, formations of the Extraandean Chubut, and the southern part of Neuquen Cordillera. Contemporaneously, in southern Chile there are marine and glacimarine sediments. The chronostratigraphic relationships between the Silurian to Permian units allow five paleogeographic stages to be distinguished. The middle Silurian-late devonian igneous rocks represent the first magmatic stage. The second stage, which is transitional to the first, is represented by a marine basin that includes the late devonian-early Carboniferous Esquel and Rio Pescado formations and the Llanquihue Complex. The third stage(early-late Carboniferous) includes granitoids of the second magmatic event that partially overlapped the first magmatic igneous belt. The fourth stage belongs to the late Carboniferous sedimentation of the Cushamen and equivalent formations. The extended early Permian magmatism was the last Paleozoic event in the studied area.

关键词： Pennsylvanian Glacimarine sedimentation Cushamen Formation North Patagonian Massif

<i>Jatropha curcas L</i>. and <i>J. macrocarpa</i>Griseb: Seed Morphology, Viability, Dormancy, Germination and Growth of Seedlings

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American Journal of Plant Sciences 2018年第9期9卷 1835-1854页

作者： Nancy E. de las M. Tavecchio Ana E. Vigliocco Oscar A. Terenti Diego Wassner Herminda E. Reinoso Hilda E. Pedranzani Laboratorio Fisiología Vegetal Facultad de Ingeniería y Ciencias Agropecuarias Universidad Nacional de San Luis Villa Mercedes Argentina departamento de Ciencias Naturales Facultad de Ciencias Exactas Físico-Químicas y Naturales Universidad Nacional de Río Cuarto Río Cuarto Argentina Estacion Experimental Agropecuaria INTA-SAN LUIS Villa Mercedes Argentina departamento de Producción Vegetal Facultad de Agronomía Cátedra de Cultivos Industriales Universidad de Buenos Aires Buenos Aires Argentina Laboratorio de Fisiología Vegetal Facultad de Química Bioquímica y Farmacia Universidad Nacional de San Luis San Luis Argentina

To achieve a good production of a crop, it is essential to know the ability of the species to successfully complete two critical stages in the life cycle such as germination and seedling establishment. In this paper we study in comparative form structure of the seed, the importance of tegument in dormancy, the effect of accelerated aging on seed germination and viability, and the early and late growth in J. curcas and J. macrocarpa. External morphology of the seeds allow difference and internally also the embryos show evident differences. J. macrocarpa germination is around 0% - 4%. The total removal of tegument showed a 50% increase and the other treatments between 0% - 10%. Aging accelerated by Tetrazolium test allowed a comparative analysis of VP and GP. J. curcas maintains both to 96 h, while J. macrocarpa the seed viability is registered along the all treatment. J. macrocarpa seeds have less synchronicity than those of J. curcas. ABA and JAs were detected in tegument of J. macrocarpa and J. curcas seeds. JA could have a roll in inhibition of germination of J. macrocarpa seeds. Early and late growth, FW and DW of root, hypocotyl, epicotyl and leaf of J. curcas were significantly different in both species.

关键词： Dormancy Germination Phytohormones Growth Seeds Viability

Duodenal duplication cyst and pancreas divisum causing acute pancreatitis in an adult male

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World Journal of Gastrointestinal Endoscopy 2010年第9期2卷 318-320页

作者： Eduardo Redondo-Cerezo Julio Pleguezuelo-Díaz mercedes López de Hierro José F Macias-Sánchez Cristina Violo Ubia maría del mar martín-Rodríguez Javier de TeresaGalván Endoscopy Unit Gastroenterology DepartmentHospital Universitario Virgen de las NievesAvenida de las Fuerzas Armadas 2Granada 18014Spain

Duodenal duplication cysts are rare congenital abnormalities which are more commonly diagnosed in infancy and ***,in rare cases,these lesions can remain asymptomatic until *** combination of duplication cyst and pancreas divisum is extremely rare and both conditions have been linked with acute recurrent *** present the case of a 37 years-old patient who presented with repeated episodes of acute *** means of magnetic resonance imaging and endoscopic ultrasonography we discovered a duplication cyst whose cavity received drainage from the dorsal *** opening the cyst cavity to the duodenal lumen with a needle knife the patient presented no further episodes in the clinical *** literature findings and therapeutic options for these abnormalities are discussed with regard to the presented case.

关键词： Duplication cyst Pancreas divisum Acute recurrent pancreatitis Endoscopic ultrasonography