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Search Results: 1 - 10 of 464519 matches for " A. Uribe-Salas "
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Comparative Study between D2EHPA and Cyanex 272 as Extractants of Mn(II) from a Leached Liquor Produced by Reductive Leaching of a Pyrolusite Ore with SO2  [PDF]
R. Pérez-Garibay, J. Martínez-Jiménez, A. Uribe-Salas, A. Martínez-Luévanos
Engineering (ENG) , 2012, DOI: 10.4236/eng.2012.49067
Abstract: This paper compares the efficiency of D2EHPA and Cyanex 272 to extract the divalent manganese cation from an actual leaching solution obtained by reductive leaching of a low-grade pyrolusite ore, using SO2 gas. The studied variables were the extractant concentration in the organic phase, the pH of the leached liquor and the volume ratio between organic phase and leached liquor. It was observed that D2EHPA is a better extractant than Cyanex272. Therefore, with the best experimental conditions found, both extractants reach a manganese recovery around 95% with five extraction stages conducted under the following conditions: 25?C, O/A = 2, 10% volume of extractant concentration in the organic phase, pH of the leached liquor before the mixing between 8 and 8.5, and one minute of mixing time for each extraction stage.
Core group approach to identify college students at risk for sexually transmitted infections
Sánchez-Alemán,Miguel A; Conde-Glez,Carlos J; Uribe-Salas,Felipe;
Revista de Saúde Pública , 2008, DOI: 10.1590/S0034-89102008000300006
Abstract: objective: to analyze the core group for sexually transmitted infections (sti) among college students. methods: cross-sectional study carried out in a convenience sample comprising 711 college students of the public university of morelos, mexico, between 2001 and 2003. sociodemographic and sexual behavior information were collected using self-applied questionnaires. herpes simplex 2 (hsv-2) infection was tested in the blood. the number of sexual partners in the last year and cocaine consumption were used as indicators to construct the dependent variable "level of sti risk" in three categories: low, medium and high risk (core group). a multinomial analysis was conducted to evaluate whether different sex behaviors were associated with the variable "level of sti risk". results: there was significant association between hsv-2 seroprevalence and the variable "level of sti risk": 13%, 5.6% and 3.8% were found in high (core group), medium and low categories, respectively. there were gender differences regarding the core group. men started having sexual intercourse earlier, had more sex partners, higher alcohol and drug consumption, higher frequency of sex intercourse with sex workers, exchanging sex for money, occasional and concurrent partners compared to women. conclusions: the study findings suggest existing contextual characteristics in the study population that affect their sex behavior. in mexico, the cultural conception of sexuality is determined mainly by gender differences where men engage in higher risky sexual behavior than women.
Heterogeneous distribution of hepatitis B serological markers in rural areas of Mexico
Juárez-Figueroa,Luis A; Uribe-Salas,Felipe Javier; Conde-González,Carlos Jesús;
Salud Pública de México , 2011, DOI: 10.1590/S0036-36342011000700006
Abstract: objective: to study the distribution of the hepatitis b antibody (anti-hbc) based on a national serosurvey from 10 mexican states showing a mean hbv prevalence higher than the national one. materials and methods: this was a cross-sectional study. during 2003, anti-hbc was analyzed at insp in 19 907 sera, and the related sociodemographic factors were determined. results: anti-hbc prevalence was greater among men, but it was also associated to age, residence in a rural area, low socio-economic status, and illiteracy. clusters of very high anti-hbc prevalence were found in several rural communities where the prevalence of anti-hbc in adults is 3 to 20 times the national average. conclusions: besides a low endemicity of hbv in mexico, distribution is heterogeneous as was shown in several of the states studied, where there are rural towns with very high prevalence of hbv markers. national serosurveys are useful tools for identifying communities with hepatitis b hyperendemicity, where focused research and control measures are needed.
La infección por el virus del papiloma humano, un posible marcador biológico de comportamiento sexual en estudiantes universitarios
Sánchez-Alemán,Miguel A; Uribe-Salas,Felipe; Conde-González,Carlos J;
Salud Pública de México , 2002, DOI: 10.1590/S0036-36342002000500009
Abstract: objective. to estimate the prevalence of human papillomavirus (hpv) among university students and to use it as a biological marker to assess sexual behavior. material and methods. a cross-sectional study was carried out between 2000 and 2001 among 194 students at universidad autónoma del estado de morelos, mexico. a data collection instrument was applied and genital samples were taken to detect oncogenic hpv dna. data were analyzed using the chi-squared test and odds ratios. results. overall hpv prevalence was 14.4%. women who had had two or more sexual partners during the previous year showed a greater risk of hpv infection (or 6.0, 95% ci 1.7-21.1), as did women who had used oral contraceptives and spermicides at their latest intercourse (or 3.0, 95% ci 1.0-8.7). males who consumed cocaine were at a greater risk of hpv infection (or 7.6, 95% ci 1.3-45.1). conclusions. hpv prevalence is relatively high. hpv is a reliable biological marker of sexual behavior among females. a greater sample size may be needed to assess its reliability among men.
Análisis químico de cianuro en el proceso de cianuración: revisión de los principales métodos
Nava-Alonso, F.,Elorza-Rodríguez, E.,Pérez-Garibay, R.,Uribe-Salas, A.
Revista de Metalurgia , 2007,
Abstract: In cyanidation, the world wide method for precious metals recovery, the chemical analysis of cyanide, is a very important, but complex operation. Cyanide can be present forming different species, each of them with different stability, toxicity, analysis method and elimination technique. For cyanide analysis, there exists a wide selection of analytical methods, but most of them present difficulties because of the interference of species present in the solution. This paper presents the different available methods for chemical analysis of cyanide: titration, specific electrode and distillation, giving special emphasis on the interferences problem, with the aim of helping in the interpretation of the results. En el proceso de cianuración para la obtención de oro y plata a partir de sus minerales, el análisis químico del cianuro es una operación compleja y de gran importancia para su control y para la descarga de sus efluentes. El cianuro se encuentra formando diferentes compuestos, cada uno de ellos con diferente estabilidad y, por lo tanto, diferente toxicidad, diferente método de análisis y diferente método de eliminación. Para el análisis de cianuro existe una gran variedad de métodos analíticos disponibles, pero estos métodos presentan dificultades a causa de la interferencia de algunos elementos presentes en la solución. El análisis resulta complicado y los resultados pueden variar según el método utilizado. En este artículo se presentan los principales métodos de análisis químico disponibles para el cianuro: volumetría, electrodo específico y destilación, presentando las interferencias y los problemas asociados a cada técnica, con el objeto de interpretar con más precisión los resultados obtenidos con cada método.
La infección por el virus del papiloma humano, un posible marcador biológico de comportamiento sexual en estudiantes universitarios
Sánchez-Alemán Miguel A,Uribe-Salas Felipe,Conde-González Carlos J
Salud Pública de México , 2002,
Abstract: Objetivo. Estimar la prevalencia de infección por el virus del papiloma humano (VPH) en estudiantes universitarios y utilizar dicha frecuencia como un marcador biológico para evaluar el comportamiento sexual. Material y métodos. Se realizó un estudio transversal, en estudiantes de la Universidad Autónoma del estado de Morelos, México, durante el periodo 2000-2001. Se aplicó un cuestionario y se colectaron muestras genitales para detectar ADN de los VPH oncogénicos. Los datos se analizaron utilizando pruebas de Ji cuadrada y razones de momios. Resultados. La prevalencia global del VPH en 194 estudiantes fue de 14.4%. Las mujeres con dos o más parejas sexuales durante el último a o presentaron mayor riesgo de infección por el VPH (RM 6.0 IC 1.7-21.1), al igual que las que utilizaron anticonceptivos hormonales y espermicidas en su última relación sexual (RM 3.0 IC 1.0-8.7). Los hombres que consumieron cocaína tuvieron más riesgo de infección por el VPH (RM 7.6 IC 1.3-45.1). Conclusiones. La prevalencia del VPH es relativamente alta. La utilización del VPH como un marcador biológico de comportamientos sexuales en mujeres es pertinente; en hombres, es necesario ampliar la muestra.
Social and Structural Factors Associated with HIV Infection among Female Sex Workers Who Inject Drugs in the Mexico-US Border Region
Steffanie A. Strathdee,Remedios Lozada,Gustavo Martinez,Alicia Vera,Melanie Rusch,Lucie Nguyen,Robin A. Pollini,Felipe Uribe-Salas,Leo Beletsky,Thomas L. Patterson
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0019048
Abstract: FSWs who inject drugs (FSW-IDUs) can acquire HIV through high risk sexual and injection behaviors. We studied correlates of HIV infection among FSW-IDUs in northern Mexico, where sex work is quasi-legal and syringes can be legally obtained without a prescription.
Sífilis materna y congénita en dos hospitales mexicanos: evaluación de una prueba diagnóstica rápida
Hernández-Trejo, María;Hernández-Prado, Bernardo;Uribe-Salas, Felipe;Juárez-Figueroa, Luis;Conde-González, Carlos J;
Revista de investigación clínica , 2006,
Abstract: objective. to estimate the prevalence of maternal and neonatal syphilis, to assess the usefulness of a rapid treponemic diagnostic test, and to evaluate the frequency of screening for syphilis during prenatal care in mexican women. material and methods. this was a cross-sectional study that included 1,322 women interviewed in two hospitals (hospital general in cuernavaca, morelos, and hospital de la mujer in mexico city). women answered a questionnaire on reproductive background, exposure to sexually transmitted infections and prenatal care. in order to diagnose syphilis, a rapid determine tp test and a latex-vdrl test were used among all participating women. positive cases were confirmed using fta-abs test. results. prevalence of serologically active syphilis was 0.3% (4/1322). using as comparison standard a combination of vdrl and fta-abs tests, the determine tp test had a sensitivity and specificity of 100%. two newborns with positive fta-abs igm, one negative with fta-abs igm and one first-trimester abortion were found from seropositive women. prenatal serum screening for syphilis was conducted in only 6.9% of women included in the study. conclusions. although the prevalence of maternal syphilis is relatively low, results show that if the situation found in the hospitals studied is shared by other hospitals in mexico, a systematic screening for maternal syphilis would help to diagnose more cases of this infection than the number reported in official figures. screening of syphilis in pregnant women using rapid tests may help in the prevention of congenital syphilis.
Prevalencia y factores asociados con sífilis y herpes genital en dos grupos de población femenina
Zamilpa-Mejía,Laura G; Uribe-Salas,Felipe; Juárez-Figueroa,Luis; Calderón-Jaimes,Ernesto; Conde-González,Carlos J;
Salud Pública de México , 2003, DOI: 10.1590/S0036-36342003001100006
Abstract: objective: to assess the frequency of hsv-2 and treponema pallidum markers and their relationship with characteristics of women during gynecological outpatient visits. material and methods: in 1994 and 1995, two populations of 388 and 448 women were studied in two hospitals; one in cuernavaca, morelos, méxico, and the other in mexico city. participants provided a blood specimen for detection of antibodies against hsv-2 and t pallidum using the western blot technique and the vdrl and fta-abs tests. also, participants answered a questionnaire on their sociodemographic characteristics and sexual behavior. the data were analyzed with the spss and egret statistical packages. results: the frequencies of hsv-2 antibodies were 28.3% in women from the first hospital, and 18.1% for those in the second. the frequencies of t pallidum antibodies were 2.3% and 1.1%, respectively. age, marital status, education level, and number of sexual partners were associated with hsv-2 infection. conclusions: low frequencies were found for infection by the microorganisms studied in both groups. hsv-2 infection was associated to exposure periods, sexual behavior, and socioeconomic level.
Marcadores serológicos de hepatitis B y C, y VIH en La Calera y Cuambio, Guerrero, México
Juárez-Figueroa,Luis A; Uribe-Salas,Felipe Javier; Conde-González,Carlos Jesús; Sánchez-Alemán,Miguel ángel;
Salud Pública de México , 2011, DOI: 10.1590/S0036-36342011000700007
Abstract: objective: to perform a hepatitis b, c, and hiv survey in an enhanced sample from two rural communities with the highest anti-hbc prevalence found in ensa 2000. materials and methods: this was a cross-sectional study.we studied the communities of la calera and cuambio, two adjacent rural towns of the district of zirándaro, guerrero, targeted because of the high prevalence of anti-hbc shown in ensa 2000.we assessed the prevalence of hepatitis b and c, and hiv serological markers and associated factors among inhabitants older than 10 years. results: a very high prevalence of hepatitis b markers associated with socioeconomic factors was confirmed, while hepatitis c prevalence was low and hiv absent in the two communities addressed. conclusions: national serosurveys are an accurate tool for identifying communities with hepatitis b high endemicity where focused research and control measures are needed.
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