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Rapid HPLC Method for determination of Rebaudioside D in Leaves of Stevia rebaudiana Bertoni Grown in the Southeast of Mexico

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American Journal of Analytical Chemistry 2014年第13期5卷 813-819页

作者： Irma Aranda-González Yolanda Moguel-Ordonez David Betancur-Ancona facultad de ingeniería Química Universidad Autónoma de YucatánMéridaMéxico Instituto Nacional de Investigaciones Forestales Agrícolas y Pecuarias(INIFAP)MococháMéxico

Stevia leaves contain glycosides on which biological activity and sweetening capacity has been reported. Besides the main glycosides—stevioside and rebaudioside A—there are minor glycosides that may contribute to the activity and thus it is important to quantify them. Rebaudioside D is one of the minor glycoside present in S. rebaudiana leaves and there are no reports of a validated method to quantify it. Therefore a simple and sensitive high performance liquid chromatography (HPLC) method was validated for the determination of rebaudioside D in leaves of Stevia rebaudiana B. grown in the southeast of México. HPLC method was performed using a C18 column (250 mm × 4.6 mm, 5 μm) and UV detector set at 210 nm. The mobile phase consisted of 32:68 (v/v) mixture of acetonitrile and sodium phosphate buffer (10 mmol/L, pH 2.6), set to a flow rate of 1.0 ml/min. The calculated parameters were: sensitivity, linearity, limit of detection (LOD), limit of quantification (LOQ), accuracy and precision. The retention time of rebaudioside D was found to be 3.47 min ± 0.04 (S.D.). The calibration curves were linear over the working range (25 - 150 μg/ml), with correlation coefficient ≥0.99 and determination coefficient ≥0.98. The calculated limit of detection (LOD) was 8.53 μg/ml, while the limit of quantitation (LOQ) was 25.85 μg/ml. The percent recoveries of fortified samples were 100% ± 10% and precision relative standard deviation was ≤2.79%. The criteria of validation showed accuracy, linearity, and precision;therefore the method is suitable for quantitative analysis of rebaudioside D in Stevia rebaudiana leaves. Rebaudioside D content (g/100g) in Morita II and Criolla varieties grown in the southeast of Mexico were 0.43 and 0.46, respectively with no significant differences (p > 0.05) between them.

关键词： Rebaudioside D Stevia Rebaudiana HPLC Validation

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Spectral Comparison of Real Spectra with Site Effects Included vs MOC-2008 Teorical Spectra for Guadalajara City, Mexico

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Open Journal of Civil Engineering 2013年第3期3卷 194-201页

作者： Héctor E. Rodríguez Lozoya Tonatiuh Domínguez Reyes Alfredo Reyes Salazar Edén Bojórquez Mora Héctor E. Rodríguez Leyva facultad de ingeniería Universidad Autónoma de Sinaloa México D.F. México Observatorio Vulcanológico Universidad de Colima México D.F. México

Guadalajara city is the capital of the Mexican federal state of Jalisco. It is located close to the Pacific coast and is subjected to a large seismic risk. We present a seismic response study for some sites along the city. We calculated response spectra of shear-waves by using seismic records of actual earthquakes registered on rock and near the source as Green functions and propagated them trough a flat and horizontal layered media using a linear equivalent method to compare them with the response spectra calculated according to the Federal Commission of Electricity (CFE) seismic design buildings Manual (MOC-2008, 2008) which is widely used as reference on construction projects in Mexico. Our results show that MOC-2008 manual underestimates the spectral amplitudes and frequency band for the response spectra.

关键词： Response Spectra Guadalajara Seismic Records Green Function

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Integration of an Objective Approach Focused on the Consumer to Evaluate the Quality of Processed Brussels Sprouts

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Food and Nutrition Sciences 2011年第9期2卷 1011-1017页

作者： Daniela Flavia Olivera Sonia Zulma Viña Ricardo Mario Ferreyra Alicia Mugridge Rodolfo Horacio Mascheroni Alicia Raquel Chaves CIDCA(Centro de Investigación y desarrollo en Criotecnología de Alimentos) CONICET La PlataUniversidad Nacional de La Plata(UNLP)La PlataArgentina MODIAL(Unidad de Investigación y desarrollo en Modelado y Diseño en ingeniería de Alimentos) Facultad de IngenieríaUniversidad Nacional de La Plata(UNLP)La PlataArgentina

Few research works focus on integration of the objective analysis of frozen vegetable quality and the preference of consumers for these products. The aim of the present work was to investigate the consumption patterns of Brussels sprouts, the degree of importance that consumers give to main attributes, and the constructions they make about product quality. For this aim, a series of surveys (snowball sampling method) were performed with consumers from four cities in Argentina. Also, the effect of different industrial operations (two blanching procedures, freezing and cooking) on texture, color, total chlorophyll content and ascorbic acid content of processed sprouts, was determined with respect to the fresh product. A function Z (overall quality) was defined to integrate the information obtained by both approaches. Taking into account the relative importance assigned by surveyed consumers to appearance, texture and nutrient content, the quality of final product obtained from different processing methods was equivalent. Most consumers, 96% of total, preferred the fresh product, which suggests that prejudging by consumers influences attempts at objective estimation of quality.

关键词： Frozen Vegetables Brassica Oleracea L.Gemmifera Quality Attributes Quality Perception

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Crystallographic Study of the TiO<sub>2</sub>Obtained by Different Synthesis Methods

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Journal of Materials Science and Chemical Engineering 2013年第6期1卷 30-37页

作者： Fidel Alejandro Cortez-Lorenzo Miguel Galván Ruiz Rufino Nava Mendoza Mario Enrique Rodriguez García Rodrigo Rafael Velazquez Castillo Centro de Física Aplicada y Tecnología Avanzada UNAM Campus Juriquilla Querétaro México División de Investigación y Posgrado Facultad de Ingeniería Universidad Autónoma de Querétaro Querétaro México División de Investigación y Posgrado Facultad de Ingeniería Universidad Autónoma de Querétaro Querétaro México CBTis 145 San Juan del Río Querétaro México

In this work, the crystal structure of titanium dioxide was studied, and the effect of the different synthesis routes on the microstructure and morphology of the nanostructures was analyzed. Samples characterization was carried out by X-ray diffraction by powders (XRD) to determine the different crystalline phases contented in the samples and using scanning electron microscopy (SEM), the morphology and topology of all samples were studied. XRD results were analyzed through Eva provided by Bruker to determine the average crystallite size. The results portrayed here showed that all the synthesis process produced anatase nanostructures with an average crystallite size smaller than 27 nm. Synthesized powders presented similar morphologies in all cases and they were homogeneous in their chemical composition.

关键词： Anatase Sol-Gel Hydrothermal Assisted Microwaves Crystallization

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Kinematic calibration of precise 6-DOF Stewart platform-type positioning systems for radio telescope applications

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Frontiers of Mechanical Engineering 2013年第3期8卷 252-260页

作者： Juan Carlos JUREGUI Eusebio E.HERNNdeZ Marco CECCARELLI Carlos LOPEZ-CAJUN Alejandro GARCIA División de Estudios de Posgrado Facultad de IngenieríaUniversidad Autónoma de Quéretaro QuéretaroQro.Mexico National Polytechnic Institute IPNSection of Graduate Studies and ResearchESIME-UPTMéxico D.F.Mexico Laboratory of Robotics and Mechatronics University of Cassino Italy Universidad Autónoma de Quéretaro Querétaro Qro.México CIATEQ A.C.AguascalientesAgs.México

The pose accuracy of a parallel robot is a function of the mobile platform ***,there is no a single value of the robot’s *** this paper,two novel methods for estimating the accuracy of parallel robots are *** the frst method,the pose accuracy estimation is calculated by considering the propagation of each error,i.e.,error variations are considered as a function of the actuator’s *** the second method,it is considered that each actuator has a constant error at any *** methods can predict pose accuracy of precise robots at design stages,and/or can reduce calibration time of existing *** example of a six degree-of-freedom parallel manipulator is included to show the application of the proposed methods.

关键词： pose errors error estimation parallel robot radio telescopes

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Effect of Domestic Wastewater as Co-Substrate on Biological Stain Wastewater Treatment Using Fungal/Bacterial Consortia in Pilot Plant and Greenhouse Reuse

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Journal of Water Resource and Protection 2018年第3期10卷 369-393页

作者： Pedroza-Camacho Lucas David Lores-Acosta Juan Camilo Rojas-Enríquez Johans Farid Mateus-Maldonado Juan Felipe Puentes Cindy Stephanie Ramírez-Rodríguez Julio Mendez-Casallas Francy Janeth Salcedo-Reyes Juan Carlos Díaz-Ariza Lucía Ana Lozano-Puentes Hair Santiago Pedroza-Rodríguez Aura Marina Programa de Biología. departamento de Ciencias Básicas Universidad de La Salle Bogotá D.C. Colombia facultad de ingeniería Departamento de Ingeniería Ambiental Universidad de La Salle Bogotá D.C. Colombia Laboratorio de Microbiología Ambiental y de Suelos Grupo de Biotecnología Ambiental e Industrial Departamento de Microbiología Facultad de Ciencias Pontificia Universidad Javeriana Bogotá D.C. Colombia Laboratorio de Películas delgadas y Nanofotonica Departamento de Física Facultad de Ciencias Pontificia Universidad Javeriana Bogotá D.C. Colombia Laboratorio Asociaciones suelo planta microorganismos (LAMIC) Grupo de Investigación en Agricultura Biológica Departamento de Biología Facultad de Ciencias Pontificia Universidad Javeriana Bogotá D.C. Colombia

In this study, a pilot wastewater treatment plant was used to evaluate the co-treatment of biological-staining residues and domestic wastewater under non-sterile conditions. A novel microbial consortia formed by Trametes versicolor, Trametes sp, Pleurotus ostreatus, Pseudomonas fluorescens, Pseudomonas azotoformans, Pseudomonas sp, Enterobacter xianfangensis and Bacillus subtillis was inoculated in an extended aeration type bio-reactor. The treatment units were operated during three consecutive cycles during a period of 147 h. After the last operating cycle, the concentrations of Chemical Oxygen demand, Biochemical Oxygen demand, Color Units, Total suspended solids, and the pH value were 1695 mg/L, 105 mg/L, 106 CU, 5), 1367 (CU), 566 mg/L (TSS) and 7.0 (pH) respectively. The reduction of pollutants load was related with the ratio of the two types of wastewater (3.5:0.5) combined to increase biodegradability, the concentration of fungi and bacteria used in the consortia (30 × 103 - 55 × 106 CUF/mL Total Fungi and 70 × 107 - 83 × 108 CFU/mL of Total Bacteria) and ligninolytic enzymes production, Laccase (13 - 96 U/L), MnP (9.8 - 39 U/L) and LiP (0.3 - 5.3 U/L). The post-treated effluent was used as irrigation water. Lolium perenne plants were watered during 60 days with post-treated effluent. The results of root weight showed that there are significant differences between the initial water and the effluent obtained after the operational cycles (p = 0.00470). The highest root weights (1 - 1.12 g) were found in plants irrigated with water obtained from the last treatment cycle.

关键词： Fungal/Bacterial Consortia Biological Staining and Domestic Wastewater Co-Treatment and Irrigation Reuse

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Influence of Contraception on Basic Vaginal States: A Prospective Study

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Health 2015年第2期7卷 238-244页

作者： Sonia Elena Fosch Cristian Yones Marta Trossero Omar Grosso Beatriz Perazzi Servicio de Atención Médica Ministerio de Salud Sa Pereira Argentina facultad de ingeniería y Ciencias Hídricas Universidad Nacional del Litoral Santa Fe Argentina departamento de Bioquímica Clínica Hospital de Clínicas Facultad de Farmacia y Bioquímica Universidad de Buenos Aires Buenos Aires Argentina

To evaluate the influence of contraceptive methods on the basic vaginal states (BVSs) in women in fertile age, 108 women consulting for birth control (14 - 45 years) were included in a prospective study. The vaginal content was sampled both before they began using the chosen contraceptive method (see below) and three months later, and then analyzed using the Balance of Vaginal Content (BAVACO) methodology. Five BVSs were defined: 1) normal microbiota;2) normal microbiota with vaginal inflammatory reaction (VIR);3) intermediate microbiota;4) bacterial vaginosis and 5) non-specific microbial vaginitis. The following contraceptive methods were considered: combined oral contraceptive pill (COCP), intrauterine device (IUD), condom (CON), the rhythm method (RHYT) and simultaneous double protection (COCP + CON). The McNemar statistical test was used. COCP (n = 71): 20 samples retained normal BVSs and two were altered;nine out of the 49 altered samples returned to normal;IUD (n = 4): two samples modified their normal BVS to III and IV;CON (n = 25): the VIR increased in 20% of the samples;RHYT (n = 6): four samples retained the normal BVS;and COCP + CON (n = 2): samples preserved their initial BVS (II). The increased frequency of BVS I in the COCP group was significant (x2 = 3.3;p = 0.04). The relative frequency of each BVS was significantly modified, attributed to the type of contraceptive method used. The intake of hormones corrects alterations and retains a normal BVS. The contraceptive methods that use an external factor of local contact either maintain or alter the microbiota and VIR.

关键词： Contraception Basic Vaginal States Vaginal Content

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Heavy Metals Removal from Swine Wastewater Using Constructed Wetlands with Horizontal Sub-Surface Flow

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Journal of Environmental Protection 2012年第8期3卷 871-877页

作者： Jorge A. Cortes-Esquivel Germán Giácoman-Vallejos Icela D. Barceló-Quintal Roger Méndez-Novelo María C. Ponce-Caballero departamento de Ciencias Básicas Universidad Autónoma Metropolitana Unidad Azcapotzalco México D.F. facultad de ingeniería Universidad Autónoma de Yucatán Mérida México

The removal efficiency of Cu and Zn from swine wastewater was evaluated as effected by three variables: the hydraulic retention time (HRT) (24, 48, 72 and 96 hours), two different plant species (Typha domingensis Pers. and Eleocharis cellulosa) and two different sizes of filter media (5 and 15 mm) using a horizontal sub-surface flow constructed wetland. From the results, a significant difference was observed in the removal efficiency of Cu and Zn with respect to different hydraulic retention times. The best results were obtained in the HRT of 96 hours for Zn where 96% removal of Zn with Typha domingensis Pers. specie with gravel of 15 mm (experimental unit 6) was achieved. For Cu, at 72 hours of HRT, the efficiency was nearly 100% in five of the six study units (1, 2, 3, 5 and 6). In contrast, in experimental unit 4 with gravel of 15 mm and without plants, only 86% Cu removal was achieved.

关键词： Swine Wastewater Typha domingensis Pers. Eleocharis cellulosa Heavy Metals Constructed Wetlands Horizontal Sub-Surface Flow

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地震光和地震地面加速度之间的时间差相关性

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Applied Geophysics 2021年第1期18卷 9-16,128页

作者： Juan Antonio Lira Maurizio Mulas facultad de Ciencias Físicas Universidad Nacional Mayor de San MarcosLima 1Peru Sección Física Departamento Académico de CienciasPontificia Universidad Católica del PerúLima 32Peru Escuela Superior Politécnica del Litoral ESPOLFacultad de Ingeniería en Ciencias de la TierraCampus Gustavo Galindo Km 30.5 Vía PerimetralP.O.Box 09-01-5863

虽然自古以来就知道地震光,但直到60年代,才拍摄下第一张地震光照片。在2007年在秘鲁发生地震期间,录下了第一部地震光录像。同样,在2016年瓜多尔地震和2017年墨西哥地震期间,记录了两部地震光电影。这些电影记录,无论是客观还是信息内... 详细信息

虽然自古以来就知道地震光,但直到60年代,才拍摄下第一张地震光照片。在2007年在秘鲁发生地震期间,录下了第一部地震光录像。同样,在2016年瓜多尔地震和2017年墨西哥地震期间,记录了两部地震光电影。这些电影记录,无论是客观还是信息内容,都有助于研究地震光。已经提出了几种解释地震光的因果机制:压电性、氡放射、流体扩散、摩擦汽化、正极洞穴和偶极电流等等。在这项工作中,我们发现了地震光和地震地面加速度之间的时间差相关性,并使用地震数据和地震光的胶片记录来解释其起源。在讨论部分,建议岩石破裂在某种程度上表现为通过感应产生静电的地震光。我们建立了一个新的感应模型,可以用于解释EQL的形成,即使地壳具有大电阻率层。该模型还解释了地震光的形成,而不需要地球表面或大气中的特殊条件。更好地理解地震光的生成过程可以提高我们对地震活动的理解,并有助于预测地震。

关键词：时差相关性地震光地震地面加速度岩石破裂

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Microstructure of <em>Annona muricata</em>L. Leaves Extract Microcapsules Linked to Physical and Chemical Characteristics

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Journal of Encapsulation and Adsorption Sciences 2018年第3期8卷 178-193页

作者： Oscar Jordán-Suárez Patricia Glorio-Paulet Leslie Vidal facultad de Ciencia de Alimentos Universidad Le Cordon Bleu Lima Perú departamento de ingeniería de Alimentos y Productos Agropecuarios Universidad Nacional Agraria La Molina Lima Perú departamento de Agroindustrias Universidad de Concepción Chillán Chile

Microstructure is closely related to techno-functional properties in microencapsulated powders intended to protect bioactive compounds. Soursop leaves provide phytochemicals that need to be protected to ensure their functionality. This investigation aimed to study the microstructure of microcapsules containing soursop leaves extract and its linkage with physical and chemical characteristics of the resulting powder. Microcapsules were prepared by spray drying using gum Arabic and maltodextrin as encapsulating agents at 5 and 10%. Powders were characterized by scanning electron microscopy, particle size analysis, solubility, infrared spectroscopy and encapsulation efficiency. Microphotographs showed spherical shape particles ranging from 0.25 to 13.87 μm, where the particles morphology depended on the concentration and the type of the encapsulant used. At higher concentration of encapsulant, there was an increase in the sphericity, integrity, size, and surface smoothness of particles. This relationship was inverse for solubility in treatments with gum Arabic. The extract encapsulation was confirmed by Fourier Transform infrared spectroscopy and encapsulation efficiency index, revealing that the treatment with maltodextrin at 10% showed a better capability for entrapment (72.12%). The results evidence that microstructure of microcapsules is closely linked to the type and concentration of encapsulant, which in turn determine the physical and chemical characteristics of powders intended for instant drinks solubility and entrapping soursop bioactive compounds.

关键词： Soursop Microencapsulation Microstructure Spray Drying Encapsulants

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