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Journal of Pharmaceutical Analysis 2017年第4期7卷 208-213页

作者： María del Mar contreras Aránzazu Morales-Soto Antonio Segura-Carretero Javier Valverde Department of Analytical Chemistry Faculty of SciencesUniversity of GranadaAvenida Fuentenueva s/n18071 GranadaSpain Research and Development Functional Food Centre (CIDAF) Bioregión BuildingHealth Science Technological ParkAvda. Del Conocimiento s/n18016 GranadaSpain

Sofosbuvir is one of the new direct-acting antiviral drugs against hepatitis C virus(HCV) infection. This drug has recently been launched into the market, and generic versions of the medication are expected to be produced by local drug producers in some countries. Therefore, new methods are required to control sofosbuvir in pharmaceuticals. In the present study, a new method based on reversed phase(RP)-ultra-high performance liquid chromatography(UHPLC) coupled to diode array detection(DAD) and mass spectrometry(MS) was developed to facilitate the qualitative and quantitative analysis of sofosbuvir in film coated tablets. A wavelength of 260 nm was selected to perform a cost-effective quantification and the method showed adequate linearity,with an R^2 value of 0.9998, and acceptable values of accuracy(75%–102%) and precision(residual standard deviation fication limits were 0.07 μg/mL and 0.36 μg/mL, ***, the use of high-resolution MS enabled us to ensure the specificity, check impurities and better sensitivity. Therefore, this methodology promises to be suitable not only for the routine analysis of sofosbuvir in pharmaceutical dosage forms, but also for potential degradants.

关键词： film coated tablets Mass spectrometry RP-UHPLC Sofosbuvir

Understanding Chemical Reactivity in Extended Systems：Exploring Models of Chemical Softness in Carbon Nanotubes

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物理化学学报 2018年第6期34卷 631-638页

作者： CáRDENAS Carlos MUNOZ Macarena contreras Julia AYERS Paul W. GóMEZ Tatiana FUENTEALBA Patricio Departamento de Flsica Facultad de Ciencias Universidad de Chile Casilla 653 Santiago Chile Centro para el Desarrollo de la Nanociencias y Nanotecnologia CEDENNA Avenida Ecuador 3493 Santiago Chile Nucleo de Matematicas Fisica y Estad

Chemical reactivity towards electron transfer is captured by the Fukui ***,this is not well defined when the system or its ions have degenerate or pseudo-degenerate ground *** such a case,the first-order chemical response is not independent of the perturbation and the correct response has to be computed using the mathematical formalism of perturbation theory for degenerate ***-degeneracy is ubiquitous in nanostructures with high symmetry and totally extended *** the size of these systems,using degenerate-state perturbation theory is impractical because it requires the calculation of many excited *** we present an alternative to compute the chemical response of extended systems using models of local softness in terms of the local density of *** local softness is approximately equal to the density of states at the Fermi ***,such approximation leaves out the contribution of inner *** order to include and weight the contribution of the states around the Fermi level,a model inspired by the long-range behavior of the local softness is *** wall capped carbon nanotubes(SWCCNT) illustrate the limitation of the frontier orbital theory in extended ***,we have used a C360 SWCCNT to test the proposed model and how it compares with available models based on the local density of ***,a simple Hü ckel approximation captures the main features of chemical response of these *** results suggest that density-of-states models of the softness along simple tight binding Hamiltonians could be used to explore the chemical reactivity of more complex system,such a surfaces and nanoparticles.

关键词： Local softness Fukui function Reactivity Carbon nanotubes Density of states

Rainwater harvesting,its prospects and challenges in the uplands of Talugtog,Nueva Ecija,Philippines

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International Soil and Water Conservation Research 2013年第3期1卷 56-67页

作者： Samuel M.contreras Teresita S.Sandoval Silvino Q.Tejada Bureau of Soils of Soils and Water Management the Philippines Bureau of Soils and Water Management the Philippines

The prospects and challenges facing eight small water impounding projects(SWIPs)in Talugtog,Nueva Ecija,an upland municipality located in Central Luzon,Philippines were evaluated using rapid appraisal and documentation of projects,interview of farmers and local officials,and a review of related studies undertaken on the same project *** challenges include the deterioration of structural facilities,inactive farmers associations,watershed degradation,and climate *** also aims to evaluate improvement and innovation in the future implementation of SWIPs as rainwater harvesting *** site was selected because it has the largest number of SWIPs established as one of the coping strategies during the 1997-1998 severe el *** of its location,it has no major irrigation systems and relies only on local rainwater storage *** study involves 8 SWIPs established in two clusters(i.e.,5 and 3 SWIPs in a watershed)as rainwater conservation and management *** indicated these clusters of SWIPs offer multiple benefits in terms of supplemental irrigation,inland fish production,and water for domestic purposes and livestock *** also serve as strategic small-scale upland structures that enhance recharging of groundwater,prevent flooding,and provide value-adding activities such as recreation,soil and water conservation,and environmental *** studies also identified their benefits at the farm and community levels as conserved rainwater through storage in SWIPs is translated into more economic ***,some SWIPs are confronted with various challenges;deterioration of structural facilities,inactive farmer associations,unabated watershed degradation,and threats of climate *** are seriously affecting the overall performance of *** actions should include the strengthening of small water impounding system associations(SWISA),repair and climate-proofing of structural facilities through the(SWISA

关键词： Rainwater harvesting Small water impounding project Upland Watershed SWISA

Climate Change and Its Influence on Agricultural Pest in Mexico

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Atmospheric and Climate Sciences 2014年第5期4卷 931-940页

作者： Carlos contreras Servin Guadalupe Galindo Mendoza Coordination for Innovation and Application of Science and Technology Autonomous University of San Luis PotosiSan Luis PotosiMexico

The present paper reviewed the researches of how they have affected agricultural pests in the territory of Mexico. It emphasizes that traditional climate models are not “predict” non-linear systems and are necessary to resort to the construction of scenarios for study. Some climate change models applied to Mexico used for this purpose obtained significant results. It showed that to better understand the ecology of pests and their hosts, it is necessary to further research the correlations between them and improve climate modeling and its consequences, to prioritize risks and improve the reliability of predictions and scenarios in the future.

关键词： el Nino(ENSO)and Its Relationship with the Agricultural Pests Climate Variability and Its Effect on Agricultural Pests Pests Plant Health Climate Change

Potential for Growing <i>Salvia hispanica</i>L., Areas under Rainfed Conditions in Mexico

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Agricultural Sciences 2015年第9期6卷 1048-1057页

作者： Genovevo Ramírez-Jaramillo Mónica Guadalupe Lozano-contreras Instituto Nacional de Investigaciones Forestales Agrícolas y Pecuarias (INIFAP)-Centro de Investigación Regional Sureste Programa para el Desarrollo de los Trópicos Mérida México Instituto Nacional de Investigaciones Forestales Agrícolas y Pecuarias (INIFAP) Campo Experimental Mocochá México

The Salvia hispanica L. is an endemic species Mexican plant, which relevance relies upon its properties as a natural source of omega 3 (α-linolenic acid), soluble and insoluble fibers, proteins, plus some other significant nutritional components. Due to the growing relevance generated by this crop, it became necessary to characterize its physical environment, as well as the natural factors related with its cultivation nationwide, aiming to find those most suitable for its production under rainfed conditions, looking forward to provide the basis to make a decision regarding where to target the agriculture promotion of such cropland. The software used for data process and analysis was the Arc/View 3.3 version. Thus, the crop requirements were recognized in order to analyze those most suitable for chia development in each one of its selected variables in the study hereby. The regionalization and mapping aimed to detect both the optimal and suboptimal potential areas for such crop were carried out, afterwards. It was finally determined that Mexico holds a total of 2,512,359 hectares with an optimal or high cultivation potential, whereas the areas with a medium or suboptimal potential are close to 3,658,089 hectares, which can be set under rainfed conditions.

关键词： Potential Rainfed Conditions Chia

Endoscopic pancreatic necrosectomy in the United States-Mexico border:A cross sectional study

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World Journal of Gastrointestinal Endoscopy 2020年第5期12卷 149-158页

作者： Antonio Mendoza Ladd Mohammad Bashashati Alberto contreras Onyedika Umeanaeto Alejandro Robles Department of Internal Medicine Division of GastroenterologyTexas Tech University Health Sciences CenterPaul L Foster School of MedicineEl PasoTX 79905United States Department of Internal Medicine Texas Tech University Health Sciences CenterPaul L Foster School of MedicineEl PasoTX 79905United States

BACKGROUND A recent expert panel issued recommendations about the technical aspects of direct endoscopic necrosectomy(DEN) for pancreatic walled-off necrosis(WON).However, significant technical heterogeneity still exists among *** To report the outcomes of our DEN technique and how it differs from a recent expert consensus statement and previous *** Medical records of patients with WON who underwent DEN from September2016-May 2019 were queried for the following information: Age, gender,ethnicity, etiology of acute pancreatitis, WON location and size, DEN technical information, adverse events(AEs) and outcomes. Adverse events were graded according to the American Society of Gastrointestinal Endoscopy Lexicon grading system. Technical success was defined as adequate lumen apposing metal stent(LAMS) deployment plus removal of ≥ 90% of necrosum. Clinical success was defined as complete resolution of WON cavity by imaging and resolution of symptoms at ≤ 3 months(mo) after last DEN. Data analysis was performed using mean and standard deviation for continuous variables,frequency and proportion for categorical variables, and median and range for interval *** A total of 21 patients underwent DEN. Most of them were Hispanic and their mean age was 51 ± 17 years. The majority of the collections were located in the body of the pancreas and the mean size was 13 cm ± 5 cm. The most common indication was persistent vomiting. Antibiotics were administered only in cases of infected necrosis. All LAMS were placed without radiological guidance,dilated the same day of deployment and removed after a mean of 27 ± 11 *** cross-sectional imaging immediately after drainage was not *** mean interval between DEN sessions was 7 ± 4 d and the mean number of DEN/patient was 3 ± 2. Technical and clinical success rates were both 95%. AEs were seen in 5 patients and included: Sepsis(2), stent migration(1), stent maldeployment(1), perforation(1). The

关键词： Endoscopic necrosectomy Technical differences Walled-off necrosis Lumen-apposing metal stents International consensus Clinical outcomes

Structural Analysis of TiC and TiC-C Core-Shell Nanostructures Produced by Pulsed-Laser Ablation

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Journal of Materials Science and Chemical Engineering 2023年第7期11卷 1-13页

作者： Luis Enrique Iniesta Piña Miguel Ángel Camacho López Rafael Vilchis Néstor Víctor Hugo Castrejón Sánchez Delfino Reyes contreras Mestría en Ciencia de Materiales Facultad de Química Campus Rosedal Universidad Autónoma del Estado de México Toluca México Laboratorio de Fotomedicina Biofotónica y Espectroscopía Láser de Pulsos Ultracortos Facultad de Medicina Universidad Autónoma del Estado de México Toluca México Centro Conjunto de Investigación en Química Sustentable UAEM-UNAM Toluca México TecNM/Tecnológico de Estudios Superiores de Jocotitlán Jocotitlán México Laboratorio de Acústica y Nanomateriales Facultad de Ciencias Campus el Cerrillo Universidad Autónoma del Estado de México Toluca México

This paper reports on the ablation process of a pure Ti solid target immersed in a C-enriched acetone solution, leading to the production of titanium carbide (TiC) and Ti-C core-shell nanostructures. The used route of synthesis is generally called pulsed laser ablation in liquid (PLAL). The presence of carbon structures in the solution contributed to the carbon content in the produced Ti-based nanomaterials. The atomic composition of the produced nanostructures was analyzed using SEM-EDS, while TEM micrographs revealed the formation of spherical TiC and core-shell nanostructures ranging from 40 to 100 nm. The identification of atomic planes by HRTEM confirmed a 10 nm diameter C-shell with a graphite structure surrounding the Ti-core. Raman spectroscopy allowed for the identification of D and G peaks for graphite and a Raman signal at 380 and 600 cm−1, assigned to TiC. The results contribute to the state-of-the-art production of TiC and Ti-C core-shell nanostructures using the PLAL route.

关键词： Laser Ablation TiC Nanoparticles Core-Shell Nanoparticles Pulsed Laser

Mesenchymal stem cell-based therapy for ischemic stroke

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Chinese Neurosurgical Journal 2016年第4期2卷 233-238页

作者： Johnathon D.Anderson Missy T.Pham Zelenia contreras Madeline Hoon Kyle D.fink Henrik J.Johansson Julien Rossignol Department of Internal Medicine Stem Cell Program University of California Davis Davis USAInstitute for Regenerative Cures University of California Davis Medical Center 2921 Stockton Blvd Room 1300 Sacramento CA 95817 USA Department of Internal Medicine Stem Cell Program University of California Davis Davis USA Department of Oncology-Pathology Karolinska InstituteCancer Proteomics Davis USA College of Medicine Central Michigan University Mt PleasantUSA

Ischemic stroke represents a major,worldwide health burden with increasing *** affected by ischemic strokes currently have few clinically approved treatment options *** currently approved treatments for ischemic stroke have narrow therapeutic windows,severely limiting the number of patients able to be *** stem cells represent a promising novel treatment for ischemic *** studies have demonstrated that mesenchymal stem cells functionally improve outcomes in rodent models of ischemic *** studies have also shown that exosomes secreted by mesenchymal stem cells mediate much of this *** the present review,we summarize the current literature on the use of mesenchymal stem cells to treat ischemic *** studies investigating the mechanisms underlying mesenchymal stem cells tissue healing effects are warranted and would be of benefit to the field.

关键词： Mesenchymal stem cells Exosomes Ischemic stroke

Effect of Nitriding Current Density on the Surface Properties and Crystallite Size of Pulsed Plasma-Nitrided AISI 316L

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Journal of Materials Science and Chemical Engineering 2015年第1期3卷 45-51页

作者： J. C. Díaz-Guillén E. E. Granda-Gutiérrez G. Vargas-Gutiérrez M. R. Díaz-Guillén J. A. Aguilar-Martínez L. álvarez-contreras Corporación Mexicana de Investigación en Materiales S.A. de C.V.-Cátedras-CONACyT Saltillo México Centro de Investigación y Estudios Avanzados del IPN Saltillo México GMyPQ Instituto de Investigaciones Eléctricas Cuernavaca México Universidad Autónoma de Nuevo León FIME-CIIIA Apodaca México Centro de Investigación en Materiales Avanzados S.C. Chihuahua México

In this work, plasma-nitrided AISI 316L stainless steel samples were performed by ion nitriding process under pulsed direct current (DC) discharge at different current densities (1 to 2.5 mA/ cm2). The effect of nitriding current density on the size of crystalline coherently diffracting domains (crystallite size) and strain grade was investigated using X-ray diffraction (XRD) coupled with Williamson-Hall method. Additionally, hardness and wear resistance of the nitriding layer were characterized using a Vickers indenter and pin-on-disk technique respectively. Results showed a decrease in crystallite size from 99 nm for untreated samples to 1.4 nm for samples nitrided at 2.5 mA/cm2 promoted both: an increase in hardness from 226 HV25g to 1245 HV25g, and a considerably decrease in volume loss by wear effect.

关键词： Plasma Nitriding Strain Crystallite Size Hardness Wear Stainless

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涂绘青铜雕塑保护工作中的决策

中国博物馆 2021年第S2期 122-127页

作者：简·康特雷拉斯-瓦尔加斯 J·以西结罗梅罗-查韦斯许梦颖(译) 墨西哥国家人类学与历史研究院国家保护修复及博物馆技术学院墨西哥城墨西哥国家人类学与历史研究院墨西哥城墨西哥国家干预博物馆中国国家博物馆北京100006

本文讨论了近些年对19世纪雕塑作品el Caballito实施修复保护的决策与过程。这座独特且重要的青铜雕塑曾因硝酸溶液不当清洗处理而严重受损。在历经多年的政治更迭后,雕塑被施以细致的检测,全面的保护结果意外地发现该雕塑存在一个早期... 详细信息

本文讨论了近些年对19世纪雕塑作品el Caballito实施修复保护的决策与过程。这座独特且重要的青铜雕塑曾因硝酸溶液不当清洗处理而严重受损。在历经多年的政治更迭后,雕塑被施以细致的检测,全面的保护结果意外地发现该雕塑存在一个早期涂层。这一发现,使得专家转而采用全新的定制涂层系统对其进行保护,尽管这与要求进行涂层处理的普遍意见相悖。

关键词：保护方案决策涂层系统雕塑涂绘