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A. Martínez-de la Cruz,S. Obregón Alfaro,Leticia M. Torres-Martínez,I. Juárez Ramírez 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.5
Bismuth tungstate Bi2W2O9 has been synthesized using diethylenetriaminepentaacetic acid (H5DTPA), an organic chelating agent of metals in an aqueous solution. The formation of the oxide was followed through characterization techniques such as XRD, TGA/DTA, and SEM. The optimum temperature to decompose the organic matrix and to form Bi2W2O9 was determined to be around 720 oC. Below this temperature, Bi2W2O9 was formed with a high content of Bi2WO6. At 720 oC particles of the Bi2W2O9 with a surface area four times higher than that obtained by a solid-state reaction were obtained. The oxide was tested as a photocatalyst on the degradation of aqueous solutions of rhodamine B under VIS radiation. The photodegradation of the dye followed a kinetic first order with an apparent constant, k = 2.8 × 10−3 minute−1and t1/2= 247 minutes for an aqueous solution of 5 mg l−1 of rhodamine B. Bismuth tungstate Bi2W2O9 has been synthesized using diethylenetriaminepentaacetic acid (H5DTPA), an organic chelating agent of metals in an aqueous solution. The formation of the oxide was followed through characterization techniques such as XRD, TGA/DTA, and SEM. The optimum temperature to decompose the organic matrix and to form Bi2W2O9 was determined to be around 720 oC. Below this temperature, Bi2W2O9 was formed with a high content of Bi2WO6. At 720 oC particles of the Bi2W2O9 with a surface area four times higher than that obtained by a solid-state reaction were obtained. The oxide was tested as a photocatalyst on the degradation of aqueous solutions of rhodamine B under VIS radiation. The photodegradation of the dye followed a kinetic first order with an apparent constant, k = 2.8 × 10−3 minute−1and t1/2= 247 minutes for an aqueous solution of 5 mg l−1 of rhodamine B.
Transanal Evisceration Caused by Rectal Laceration
Aleix Martínez Pérez,María Teresa Torres Sánchez,Jose Manuel Richart Aznar,Eva María Martí Martínez,Manuel Martínez-Abad 대한대장항문학회 2014 Annals of Coloproctolgy Vol.30 No.1
Transrectal evisceration caused by colorectal injury is an unusual entity. This pathology is more frequent in elderly patients and it is usually produced spontaneously. Rectal prolapse is the principal predisposing factor. An 81-year-old woman was taken to the hospital presenting exit of intestinal loops through the anus. After first reanimation measures, an urgent surgery was indicated. We observed the absence of almost every small intestine loop in the abdominal cavity; these had been moved to the pelvis. After doing the reduction, a 3 to 4 cm linear craniocaudal perforation in upper rectum was objectified, and Hartmann’s procedure was performed. We investigated and knew that she frequently manipulate herself to extract her faeces. The fast preoperative management avoided a fatal conclusion or an extensive intestinal resection. Reasons that make us consider rectal self-injury as the etiologic factor are explained.
R. Estrada-Martínez,E. Favela-Torres,N. O. Soto-Cruz,H. B. Escalona-Buendía,G. Saucedo-Castañeda 한국생물공학회 2019 Biotechnology and Bioprocess Engineering Vol.24 No.2
A solid standard mixture (SSM) representing the annual composition of fresh fruits and vegetables residues generated at the Supply Center in Mexico City was used for bioethanol production. This type of residues allows bioethanol production with a single thermal pretreatment instead of hard thermochemical or enzymatic treatments. The release of fermentable carbohydrates from the SSM by a mild thermal pretreatment was firstly optimized. After that, mixed and single cultures of Saccharomyces cerevisiae, Scheffersomyces stipitis, and Schwanniomyces occidentalis were evaluated for bioethanol production. The maximum ethanol production, 282.61 ± 13.09 L ethanol per ton of dry matter (DM), was reached using a severity factor (SF) of 2.35 and a mixed culture composed of Saccharomyces cerevisiae, Scheffersomyces stipitis, and Schwanniomyces occidentalis. The improved lab scale conditions were evaluated in a pilot scale (18 Kg) stirred bioreactor with an SF of 2.35 and the mixed culture, obtaining 245.72 ± 17.76 L ethanol per ton DM. The obtained results demonstrate for the first time the use of fresh fruits and vegetables residues for bioethanol production under solid-state culture conditions without any thermochemical or enzymatic pre-treatment.
Bi2InTaO7 compounds as promising photocatalysts for marine plankton removal
Leticia M. Torres-Martínez,Isaías Juárez-Ramírez,Juan S. Ramos-Garza,Francisco Vázquez-Acosta,Ricardo Gómez,ZhengYi Fu,Soo Wohn Lee 한양대학교 세라믹연구소 2011 Journal of Ceramic Processing Research Vol.12 No.1
The removal of marine plankton, red (Amphidium carterae), and green (Tetraselmis suecica) tide algae, by heterogeneous photocatalysis was carried out using pyrochlore-type semiconductors. The semiconductor, Bi2InTaO7 , was prepared by the solgel method and a solid state reaction. The XRD patterns evidence formation of the pyrochlore phase in the sol-gel materials calcined at low temperatures (600-800 oC). Nanostructured sol-gel materials were observed by SEM. The sol-gel preparation allowed the formation of the pyrochlore-type compound with specific surface areas (7-13 m2g−1) higher than the solid obtained by solid state preparation (< 5 m2g−1). Band gap (Eg) values between 2.1-2.7 eV determined by UV-Vis spectroscopy were obtained. Bi2InTaO7 photocatalysts prepared by the sol-gel method were able to eliminate Tetraselmis suecica and Amphidium carterae algae totally after 50 minutes of UV-irradiation, whereas Bi2InTaO7 by solid state preparation needed more than 1 h.
Analysis of activity in open-source communities using social network analysis techniques
María del Rocío Martínez-Torres 기술경영경제학회 2014 ASIAN JOURNAL OF TECHNOLOGY INNOVATION Vol.22 No.1
mechanism by which the development of the project is supported. The main objective of this paper is to analyse the online participation in virtual communities using social network analysis techniques in order to obtain the main patterns of behaviour of users within communities. Several open-source communities related to Linux ports to embedded processors have been studied, obtaining a set of indicators by modelling them as a social network. Exploratory factor analysis has been used to extract the main dimensions related to the participation process. Participation inequality, hierarchy and the cohesion of the community constitute the main dimensions characterizing the participation mechanism within communities. Obtained results highlight the necessity of guiding the organization and development of the community to achieve successful target software.
Hernández-Silva Gabriela,López-Torres Aideé S.,Maldonado-Rosas Israel,Mata-Martínez Esperanza,Larrea Fernando,Torres-Flores Víctor,Treviño Claudia L.,Chirinos Mayel 대한남성과학회 2021 The World Journal of Men's Health Vol.39 No.4
Purpose: Andrology research has evolved notoriously in the latest years, particularly since male factor contribution to couple infertility has been undoubtedly demonstrated. However, sperm function investigations results are sometimes contradictory, probably as a result of the use of different sperm processing techniques. In this work, we underwent a systematic functional comparison of human sperm samples simultaneously processed by swim-up and density gradient centrifugation, which are the preferred sperm processing methods used in basic and clinical laboratories. Materials and Methods: To compare functional characteristics of sperm isolated by swim-up and density gradient centrifugation followed by incubation at different times under capacitating conditions. Results: Semen samples processed in parallel by these two procedures resulted in sperm preparations with significant differences in redox state, spontaneous intracellular calcium oscillations, hyperactivation, protein tyrosine phosphorylation, and acrosome reaction responsivity to calcium ionophore. Such differences showed time-dependent specific patterns for spontaneous intracellular calcium oscillations, hyperactivation and protein tyrosine phosphorylation. Sperm retrieved by density gradient centrifugation showed more hyperactivation and tyrosine phosphorylation than swim-up sperm, suggesting a higher degree of capacitation. Conclusions: Our results account for functional differences observed in spermatozoa processed with these two methods and therefore may contribute to a better interpretation of outcomes obtained in different laboratories as well as to improve experimental designs aimed to study sperm physiology and fertility potential.
Functional and Structural Effects of Amyloid-beta Aggregate on Xenopus laevis Oocytes
Jorge Parodi,Ataúlfo Martínez-Torres,Lenin Ochoa-de la Paz,Ricardo Miledi 한국분자세포생물학회 2012 Molecules and cells Vol.34 No.4
Xenopus laevis oocytes exposed to amyloid- aggregate generated oscillatory electric activity (blips) that was recorded by two-microelectrode voltage-clamp. The cells exhibited a series of “spontaneous” blips ranging in amplitude from 3.8 0.9 nA at the beginning of the recordings to 6.8 1.7 nA after 15 min of exposure to 1 M aggregate. These blips were similar in amplitude to those induced by the channel-forming antimicrobial agents amphotericin B (7.8 1.2 nA) and gramicidin (6.3 1.1 nA). The amyloid aggregate-induced currents were abolished when extracellular Ca2+ was removed from the bathing solution, suggesting a central role for this cation in generating the spontaneous electric activity. The amyloid aggregate also affected the Ca2+-dependent Cl- currents of oocytes, as shown by increased amplitude of the transient-outward chloride current (Tout) and the serum-activated, oscillatory Cl- currents. Electron microcopy revealed that amyloid aggregate induced the dissociation of the follicular cells that surround the oocyte, thus leading to a failure in the electro-chemical communication between these cells. This was also evidenced by the suppression of the oscillatory Ca2+-dependent ATP-currents, which require proper coupling between oocytes and the follicular cell layer. These observations, made using the X. laevis oocytes as a versatile experimental model, may help to understand the effects of amyloid aggregate on cellular communication.
Natural products in the research of cholesterol gallstones
Ibrahim Guillermo Castro-Torres,Minarda De la O-Arciniega,Janeth Gallegos-Estudillo,Mariano Martínez-Vázquez,Elia Brosla Naranjo-Rodríguez,Miguel Ángel Domínguez-Ortíz,Jesús Samuel Cruz-Sánchez 셀메드 세포교정의약학회 2013 TANG Vol.3 No.3
Cholesterol gallstones are a digestive disease of high prevalence that has many risk factors; for this reason, research has focused mainly on how to prevent it rather than how to treat it. Many molecules of the hepatic, bile and intestinal systems are involved in the pathophysiology of this disease, making it very difficult to find a therapeutic target. The pharmacological treatment is limited, so when gallstones generate symptoms, medical treatment indicates gallbladder removal. Ursodeoxycholic acid is used to dissolve cholesterol stones, and ezetimibe and statins are other drugs with possible applications in the treatment of this disease. Given the small number of drugs that have been developed for treating this disease, the research of natural products becomes of paramount importance. Resources such as black radish, glucosinolates, fenugreek, capsaicin, curcumin, garlic, and onion, have all shown significant effects in the prevention and treatment of cholesterol gallstones. In this review, we made a synthesis of the scientific reports that deal with these natural products and that can serve as antecedents for finding a way to treat the most common disease of the gallbladder.
Rheology and gel point of the enzymatic hydrolysis of urea in the presence of urease
R. Serrato-Millán,L. Medina-Torres,F. Calderas,B.L. España-Sánchez,M. Estevez,A.R. Hernandez-Martínez,M. Cruz-Soto,I.C. Sánchez,R. Gómez-García,I. Sánchez-Betancourt,M.C. Velasquillo-Martínez,G. Luna- 한국유변학회 2017 Korea-Australia rheology journal Vol.29 No.1
This study reports on the rheology of the gelation kinetics of raw chitosan (CTS) solutions (2% w/v) produced by enzymatic hydrolysis of urea at different urea concentrations (40, 50, 60, 80, and 100 mM) in the presence of urease at 1 U/mL. Viscoelastic parameters and pH values were evaluated during gelation process and the rheological properties of CTS hydrogels produced were monitored after 24 h at 37°C to simulate human body temperatures. pH measurements suggest that above some critical urea concentration (50 mM) the time required (tgel) to reach the critical pH gelation shows no dependence on urea concentration (tgel was ca. 70 minutes). Above 50 mM of urea concentration, CTS hydrogels exhibit an elastic modulus G' higher than the viscous modulus G'' with no frequency dependence characteristic of a gel behavior. Gelation kinetics analyzed by rheology suggest that the G' (i.e., structure) development depends on urea concentration during solution neutralization.