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Elisa Leyva,Carlos Montalvo,Socorro Leyva,Edgar Moctezuma 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.5
The degradation of pyridine, widely used in the synthesis of vitamins, drugs, rubber chemicals, herbicides and pesticides, can be photocatalyzed by semiconductor catalysts. Since zinc oxide promotes faster pyridine photocatalytic oxidation reactions than TiO2, the former appears to be a suitable alternative to TiO2 for water treatment contaminated with pyridine. The photodegradation efficiency was negligible when the photolysis was carried out in the absence of any catalyst. The formation and eventual disappearance of intermediate organic reaction products during the photocatalytic oxidation of pyridine was monitored by a combination of analytical techniques such as UV-Vis, HPLC, TOC and NMR. Based on experimental observations, an alternative mechanism is proposed for the photocatalytic oxidation of pyridine. In addition, the kinetic parameters of the Langmuir-Hinshelwood model that describe the initial reaction rate for the photocatalytic degradation of pyridine over TiO2 and ZnO are presented. The degradation of pyridine, widely used in the synthesis of vitamins, drugs, rubber chemicals, herbicides and pesticides, can be photocatalyzed by semiconductor catalysts. Since zinc oxide promotes faster pyridine photocatalytic oxidation reactions than TiO2, the former appears to be a suitable alternative to TiO2 for water treatment contaminated with pyridine. The photodegradation efficiency was negligible when the photolysis was carried out in the absence of any catalyst. The formation and eventual disappearance of intermediate organic reaction products during the photocatalytic oxidation of pyridine was monitored by a combination of analytical techniques such as UV-Vis, HPLC, TOC and NMR. Based on experimental observations, an alternative mechanism is proposed for the photocatalytic oxidation of pyridine. In addition, the kinetic parameters of the Langmuir-Hinshelwood model that describe the initial reaction rate for the photocatalytic degradation of pyridine over TiO2 and ZnO are presented.
Leyva Leal, Lisandra,Choi, Oe-chool(최외출),Lee, Jeong Ju(이정주) 충북대학교 국제개발연구소 2020 사회적경제와 정책연구 Vol.10 No.1
1970년대 한국에서 시작한 새마을운동은 한 세대 내에서 국가를 빠른 시간 내에 발전시킨 중요한 요인 중의 하나이다. 쿠바의 농촌개발은 국민들의 삶의 질을 개선하고, 농촌지역에서 중요한 변혁을 도모하고자 한다. 이 연구는 새마을운동과 비교・분석을 통해서 쿠바의 농촌개발을 향상시키는데 그 목적이 있으며, 정부의 역할, 자원의 활용성, 그리고 지역사회 참여를 비교분석을 위한 기준으로 설정하였다. 연구의 결과는 다음과 같다. 첫째, 정부의 역할은 지역사회에서 정부의 지원을 필요로 있고, 자원공급과 가이드를 필요로 하는 주요 문제들을 다루어야 하며, 동시에 마을 주민들에게 실행될 프로젝트를 스스로 결정할 수 있는 권한을 주어야 한다. 둘째, 정부의 지원과 민간부문의 기부를 통한 민관협력이 농촌지역의 발전을 촉진하기 위한 자원 공급에 중요한 열쇠가 될 수 있다. 셋째, 지역사회의 프로젝트가 실제로 집행되기 위해서는 주민의 참여를 촉진하는 인센티브 제도가 필수적이다. Saemaul Undong of Korea during the 1970s was considered one of the main leaders behind the rapid development of the country. Rural development in Cuba aims to improve the quality of life of its citizens and to contribute towards a significant transformation in rural areas. This research aims to improve the Rural Development of Cuba by analyzing and comparing its development with Saemaul Undong. This research was conducted by criteria through a qualitative research methodology for comparative analysis that included the role of government, the availability of resources, and community participation. The research findings show that government"s role should first address major issues that need support, resources, or guidance in the community, while at the same time empowering citizens to determine the projects in their own communities that are to be implemented. Second, a combination of support from the government and private donations could be the key to supply the resources required to improve the development of rural areas. Finally, an incentive system that encourages greater participation for citizens is essential to the realization of projects in rural communities.
Francisco Javier Leyva-Jiménez,Jesús Lozano-Sánchez,Isabel Borrás-Linares,David Arráez-Román,Antonio Segura-Carretero 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.79 No.-
A manufacturing design and control of bioactive ingredients from Aloysia citriodora was performedapplying microwave-assisted extraction (MAE). Thus, a Response Surface Methodology based on CentralComposite Design 23 model was performed to monitor the matrix behavior. The factors were extractiontime, percentage of solvent and temperature. The chosen responses were extraction yield andphytochemicals recovery. The design allowed tofind the optimal conditions for each response and tovalidate them in order to attain high quality ingredients. These results pointed out that MAE is a noveltechnique which could be used to improve the new functional ingredient development.
Managing rebound pain after regional anesthesia
Felipe Muñoz-Leyva,Javier Cubillos,Ki Jinn Chin 대한마취통증의학회 2020 Korean Journal of Anesthesiology Vol.73 No.5
Rebound pain after regional anesthesia can be defined as transient acute postoperative pain that ensues following resolution of sensory blockade, and is clinically significant, either with regard to the intensity of pain or the impact on psychological well-being, quality of recovery, and activities of daily living. Current evidence suggests that it represents an unmasking of the expected nociceptive response in the absence of adequate systemic analgesia, rather than an exaggerated hyperalgesic phenomenon induced by local anesthetic neural blockade. In the majority of patients, it does not appear to significantly impact cumulative postoperative opioid consumption, quality of recovery, or patient satisfaction, and is not associated with longer-term sequelae such as persistent post-surgical pain. Nevertheless, it must be considered whenever regional anesthesia is incorporated into perioperative management. Strategies to mitigate the impact of rebound pain include routine prescribing of a systemic multimodal analgesic regimen, as well as patient education on appropriate expectations regarding block offset and expected surgical pain, and timely initiation of analgesic medication. Prolonging the duration of action of regional anesthesia with continuous catheter techniques or local anesthetic adjuncts may also help alleviate rebound pain, although further research is required to confirm this.
Herian A. Leyva,Edén Bojórquez,Juan Bojórquez,Alfredo Reyes,Fabrizio Mollaioli,Omar Payán,Leonardo Palemón,Manual A. Barraza 국제구조공학회 2024 Structural Engineering and Mechanics, An Int'l Jou Vol.90 No.3
Most of existing buildings in Mexico City are made of reinforced concrete (RC), however, it has been shown that they are very susceptible to narrow-band long duration ground motions. In recent years, the use of dual systems composed by Buckling Restrained Braces (BRB) has increased due to its high energy dissipation capacity under reversible cyclical loads. Therefore, in this work the behavior of RC buildings with BRB is studied in order to know their performance, specifically, the energy distribution through height and response transformation factors between the RC and simplified systems are estimated. For this propose, seven RC buildings with different heights were designed according to the Mexico City Seismic Design Provisions (MCSDP), in addition, equivalent single degree of freedom (SDOF) systems were obtained. Incremental dynamic analyses on the buildings under 30 narrow-band ground motions in order to compute the relationship between normalized hysteretic energy, maximum inter-story drift and roof displacement demands were performed. The results shown that the entire structural frames participate in energy dissipation and their distribution is independent of the global ductility. The results let propose energy distribution equations through height. Finally, response transformation factors between the SDOF and multi degree of freedom (MDOF) systems were developed aimed to propose a new energy-based approach of BRB reinforced concrete buildings.
N.A. Medellin-Castillo,R. Leyva-Ramos,E. Padilla-Ortega,R. Ocampo Perez,J.V. Flores-Cano,M.S. Berber-Mendoza 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.6
The adsorption of fluoride from water on bone char (BC) was investigated in this work, and the fluorideadsorption capacity of BC was compared to that of hydroxyapatite (HAP). The adsorption capacity of BCand HAP drastically increased while decreasing the pH from 7.0 to 5.0. Furthermore, the fluorideadsorption on BC was due to its HAP content and was not considerably affected by the presence of theanions Cl-, HCO3-, CO32-, SO42-, NO3- and NO2-. The mechanism of fluoride adsorption on BC wasattributed to electrostatic interactions between surface charge of BC and fluoride ions in solution.
LMI-Based Robust Controllers for DC-DC Cascade Boost Converters
Carlos Andres Torres-Pinzon,Roberto Giral,Ramon Leyva 전력전자학회 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.4
This paper presents two different robust controllers for boost converters with two stages in a cascade. The first robust controller is monovariable; that is, the duty-cycle is the same for the two switches. The monovariable controller ensures that some prescribed constraints on pole placement and control effort are met, and optimizes the load disturbance rejection, while takes into account the uncertainty in certain parameters. The first controller is then compared with a multivariable robust controller; that is, with independent duty cycles in each switch. The multivariable controller takes into account the same uncertainty, constraints and optimization function. The comparison shows that the multivariable controller performs better at the expense of a slightly more complex implementation; that is, the multivariable controller provides a better rejection of the load disturbance. The paper also describes simulations and experimental results that are in perfect agreement with theoretical derivations.