Hydrolysis catalyst effect on the textural and structural properties of sol-gel mixed oxides TiO₂-CeO₂

Félix Galindo-Hernández,Gloria del Ángel,Carlos Guzmán,Ricardo Gómez 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.6

Sol-gel TiO2-CeO2 semiconductors were synthesized at pH 3 and 9 using titanium alkoxide as the initial reactant; and either nitric acid or ammonium hydroxide as hydrolysis agents. The gels annealed at 473, 673 and 873 K were characterized by nitrogen adsorption,X-ray diffraction and Raman spectroscopy. The surface fractal dimension, crystallite size, titanium deficiency and electron density were calculated by the Frenkel-Halsey-Hill method, Rietveld refinement, and Fourier electron density map, respectively. Mesoporous materials showing high specific surface areas (250-99m2/g for pH 3 and 267-88 m2/g for pH 9) were obtained in both preparations. Anatase and anatase-cerianite crystalline phases were observed by X-ray diffraction in the samples prepared at pH 3 and pH 9 respectively. Nanocrystalline structures (from 7.1 to 43.6 nm) and an important titanium deficiency, depending on the synthesis conditions are reported. The Fourier electron density maps showed that for the semiconductors prepared at pH 3 the electron density was contracted in comparison with the samples synthesized at pH 9 where enlarged electron density maps were observed. A good agreement between the electron density maps and the surface fractal dimensions was obtained. Sol-gel TiO2-CeO2 semiconductors were synthesized at pH 3 and 9 using titanium alkoxide as the initial reactant; and either nitric acid or ammonium hydroxide as hydrolysis agents. The gels annealed at 473, 673 and 873 K were characterized by nitrogen adsorption,X-ray diffraction and Raman spectroscopy. The surface fractal dimension, crystallite size, titanium deficiency and electron density were calculated by the Frenkel-Halsey-Hill method, Rietveld refinement, and Fourier electron density map, respectively. Mesoporous materials showing high specific surface areas (250-99m2/g for pH 3 and 267-88 m2/g for pH 9) were obtained in both preparations. Anatase and anatase-cerianite crystalline phases were observed by X-ray diffraction in the samples prepared at pH 3 and pH 9 respectively. Nanocrystalline structures (from 7.1 to 43.6 nm) and an important titanium deficiency, depending on the synthesis conditions are reported. The Fourier electron density maps showed that for the semiconductors prepared at pH 3 the electron density was contracted in comparison with the samples synthesized at pH 9 where enlarged electron density maps were observed. A good agreement between the electron density maps and the surface fractal dimensions was obtained.

Determinants of enrollment in community based health insurance among men in Rwanda: A case study of Musanze District

Félix NDAYISABA,진기남,구준혁,차선미 사단법인 대한보건협회 2020 대한보건연구 Vol.46 No.2

Purpose: Community based health insurance(CBHI) is a major concern especially in developing countries. CBHI was designed to help people access to healthcare services at reasonable cost. Considering that men are the key decision makers in family, we need to understand what factors influence the decision to enroll in CBHI. This study aims to assess the determinants that influence the enrollment in the scheme by Rwandan men. Methods: For this study, we selected cases from Musanze District, one of the thirty districts in Rwanda. The questionnaires were distributed to Rwandan men who have not enrolled in the CBHI yet. By using quota sampling method, we surveyed 100 respondents. A chi-square test was conducted to understand the overall relationship between the measured variables. After that, logistic regression analysis was performed based on the Anderson model to identify how predisposing factors, enabling factors, and need factors influence the intention to enroll in CBHI. Main Results: The chi-square test reported that age, decision maker type, income, social network, size of household, distance to healthcare facility, perceived health status and perceived service quality were related to intention to enroll in CBHI. These relationships were found to be statistically significant. By using logistic regression analysis, we found statistically significant factors: the size of household, attitude toward CBHI, and income. Conclusion: This results imply that CBHI scheme would encounter with sustainability problems. The larger families could be hesitant to enroll in CBHI because they need to mobilize large amounts of cash all at once. Adopting monthly payment instead of requesting annual payment or flat rate payment regardless of family size can be considered. In addition, the benefits package needs to be redesigned to attract higher-income groups to enroll in CBHI.

Diagnostic Yield and Therapeutic Impact of Rectal Retroflexion: A Prospective, Single-Blind Study Conducted in Three Centers

Félix Téllez-Ávila,Josué Barahona-Garrido,Sandra García-Osogobio,Gustavo López-Arce,Jesús Camacho-Escobedo,Angela Saúl,Salvador Herrera-Gómez,Javier Elizondo-Rivera,Rafael Barreto-Zúñiga 대한소화기내시경학회 2014 Clinical Endoscopy Vol.47 No.1

Background/Aims: No clear data have been established and validated regarding whether rectal retroflexion has an important and therapeutic impact. The aim of the present study was to evaluate the diagnostic yield and therapeutic impact of rectal retroflexion compared with straight view examination. Methods: A prospective single-blind study was conducted. Consecutive patients evaluated between October 2011 and April 2012 were included. Results: A total of 934 patients (542 women [58%]) were included. The mean age was 57.4±14.8 years. Retroflexion was successful in 917 patients (98.2%). Distinct lesions in the anorectal area were detected in 32 patients (3.4%), of which 10 (1%) were identified only on retroflex view and 22 (2.4%) on both straight and retroflex views. Of the 32 identified lesions, 16 (50%) were polyps, nine (28.1%) were angiodysplasias, six (18.8%) were ulcers, and one (3.1%) was a flat lesion. All 10 patients (1%) in whom lesions were detected only by rectal retroflexion showed a therapeutic impact. Conclusions: Rectal retroflexion has minimal diagnostic yield and therapeutic impact. However, its low rate of major complications and the possibility of detecting lesions undetectable by straight viewing justify its use.

Grouped Approach for the Design of H.264/AVC Motion Estimation Architectures

Sebastián López,Gustavo M. Callicó,Félix Tobajas,Valentín de Armas,José F. López,Roberto Sarmiento 한국전자통신연구원 2008 ETRI Journal Vol.30 No.6

This letter presents a novel approach for organizing computational resources into groups within H.264/AVC motion estimation architectures, leading to reductions of up to 75% in the equivalent gate count with respect to state-of-the-art designs

Development of artificial neural networks to predict membrane fouling in an anoxic-aerobic membrane bioreactor treating domestic wastewater

Schmitt, Fé,lix,Banu, Rajesh,Yeom, Ick-Tae,Do, Khac-Uan Elsevier 2018 Biochemical engineering journal Vol.133 No.-

<P><B>Abstract</B></P> <P>An artificial neural network (ANN) was first developed to predict the transmembrane pressure in an anoxic-aerobic membrane bioreactor (AO-MBR) treating domestic wastewater. A few studies about prediction of membrane fouling in MBRs using ANNs have been published so far, even though our recent work indicates that ANNs show a great potential for this application. In this study, 10 parameters linked to wastewater treatment and measured in the different parts of the AO-MBR system were used as the input variables of the ANN. The goal was to select the most relevant input parameters to predict the evolution of the transmembrane pressure based on the performances of the ANN. An ANN model was selected for its satisfying performances (<I>R</I> <SUP>2</SUP> = 0.850). In conclusion, ANNs could be a valid method to predict membrane fouling in AO-MBR systems treating domestic wastewater.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A set of ANNs is first developed to predict membrane fouling in AO-MBR. </LI> <LI> An optimal set of parameters was identified to predict TMP using ANN efficiently. </LI> <LI> High performances were reached (R<SUP>2</SUP> = 0.850) for the developed ANN. </LI> <LI> ANN model have shown high potential to predict membrane fouling. </LI> </UL> </P>

A pH/Temperature-Sensitive s-IPN Based on Poly(vinyl alcohol), Poly(vinyl methyl ether-alt-maleic acid) and Poly(vinyl methyl ether) Prepared by Autoclaving

Karla F. García-Verdugo,Andya J. Ramírez-Irigoyen,Mónica Castillo-Ortega,Dora E. Rodríguez-Félix,Jesús M. Quiroz-Castillo,Judith Tánori-Córdova,Francisco Rodríguez-Félix,Antonio Ledezma-Pérez,Teresa d 한국고분자학회 2022 Macromolecular Research Vol.30 No.6

A novel semi-interpenetrating polymer network (s-IPN) based on the entrapment of a thermosensitive polymer, the poly(vinyl methyl ether) (PVME), within a crosslinked 3D structure of poly(vinyl alcohol) (PVA) and poly(vinyl methyl etheralt- maleic acid) (COP) was synthesized by an autoclaving process. The preparation method avoids the use of toxic crosslinkers and allows the simultaneous sterilization of material. The PVA/COP/PVME hydrogel were characterized by Fourier transform infrared spectroscopy, thermal techniques, swelling kinetic measurements, scanning electron microscopy, and rheological analysis. The entrapment of PVME within the hydrated polymer framework significantly modified its transition temperature at pH 7.4 and pH 3 conditions. The swelling kinetics of the s-IPN were dependent on pH (7.4, 3 and 1), and temperature (25 and 37℃). The interpenetrated polymer chains reduced the internal pore sizes of crosslinked network without altering its elastic, solid-like behavior. The loading and in vitro release of 5-fluorouracil, a chemotherapeutic agent, from hydrogel systems were studied at different temperature and pH values. The hydrogels showed a sustained drug release up to 5 h at 37℃, in different pH media. The s-IPN exhibited a promising performance for a range of biomedical applications, in particular, for the controlled drug delivery in response to the pH and temperature conditions.

Corrigendum: Surgical management of palatal teratoma (epignathus) with the use of virtual reconstruction and 3D models: a case report and literature review

Cynthia Minerva Gonzalez-Cantu,Pablo Juan Moreno-Peña,Mayela Guadalupe Salazar-Lara,Pablo Patricio Flores García,Fernando Félix Montes-Tapia,Victor Hugo Cervantes-Kardasch,Yanko Castro-Govea 대한성형외과학회 2021 Archives of Plastic Surgery Vol.48 No.6

Fetoscopic laser photocoagulation for twin-to-twin transfusion syndrome treatment: initial experience in tertiary reference center in Brazil

Maurício Mendes Barbosa,Eduardo Félix Martins Santana,Hérbene José Figuinha Milani1,Julio Elito Júnior,Edward Araujo Júnior,Antônio Fernandes Moron,Luciano Marcondes Machado Nardozza 대한산부인과학회 2018 Obstetrics & Gynecology Science Vol.61 No.4

ObjectiveTo evaluate the initial maternal and perinatal outcomes of fetoscopic laser photocoagulation for the treatment oftwin-to-twin transfusion syndrome (TTTS) in a referral center in Brazil. MethodsThis prospective observational study analyzed 24 fetoscopic laser photocoagulation procedures at 18.26 weeks ofgestation. TTTS severity was determined using the Quintero classification. Blood vessels that crossed the interamnioticmembrane were nonselectively photocoagulated. The χ2 test and Mann-Whitney U test were used for the statisticalanalysis. ResultsThe mean (±standard deviation) age of pregnant women, gestational age at surgery, surgical time, gestational age atbirth, and newborn weight were 32.2±4.1 years, 20.7±2.9 weeks, 51.8±16.7 minutes, 30.5±4.1 weeks, and 1,531.0±773.1g, respectively. Using the Quintero classification, there was a higher percentage of cases in stage III (54.2%), followedby stages IV (20.8%), II (16.7%), and I (8.3%). Ten (41.7%) donor fetuses died and 14 (58.3%) donor fetuses surviveduntil the end of gestation. Placental insertion location (anterior vs. posterior) did not affect the incidence of iatrogenicseptostomy, surface bleeding, and premature rupture of membranes until the end of gestation. The death rate ofdonor and recipient fetuses before 24th gestational week increased with severity of TTTS. ConclusionThe maternal and perinatal outcomes resulting from the implementation of a new minimally invasive surgicaltechnique are in line with those obtained in major centers worldwide, considering the learning curves andinfrastructures.

Performance of the cobas u 701 Analyzer in Urinary Tract Infection Screening

Victoria Ortiz de la Tabla,,Gregoria Gázquez,Ana Infante,Coral Martin,Fernando Buñuel,Félix Gutiérrez 대한진단검사의학회 2019 Annals of Laboratory Medicine Vol.39 No.5

Background: Negative urine cultures to rule out urinary tract infections (UTI) generate a considerable laboratory workload; thus, a rapid screening test is desirable. We evaluated the performance of a new automated microscopy analyzer, cobas u 701 (Roche Diagnostics International, Rotkreuz, Switzerland) for the screening of UTI, and developed a rule-out strategy to reduce the number of samples requiring culture. We also assessed squamous epithelial cell (SEC) count as a predictor of culture contamination. Methods: In total, 1,604 urine samples from outpatients were analyzed with cobas u 701 and culture. Bacterial (BAC) and white blood cell (WBC) counts were used for sample interpretation. To determine a useful cut-off point to predict negative cultures, we selected the highest sensitivity and specificity values obtained from ROC curves. Diagnostic accuracy by age and gender was evaluated. Results: Urine culture showed growth of ≥104 colony forming units (CFU)/mL in 256 samples (16.0%). The highest sensitivity (91.8%) and specificity (68.4%) were obtained for cut-off points of 119 BAC/μL and 22 WBC/μL. The combination of BAC and WBC improved the performance of the rule-out strategy with a low rate of false-negative results (1.5%) and a high negative predictive value (NPV, 97.3%). Fifty-seven percent of the samples would not have required culture. SEC count was a poor predictor of culture contamination. Conclusions: cobas u 701 can substantially reduce the number of urine samples requiring culture, with a low false-negative rate and a high NPV.

A synthetic ion transporter that disrupts autophagy and induces apoptosis by perturbing cellular chloride concentrations

Busschaert, Nathalie,Park, Seong-Hyun,Baek, Kyung-Hwa,Choi, Yoon Pyo,Park, Jinhong,Howe, Ethan N. W.,Hiscock, Jennifer R.,Karagiannidis, Louise E.,Marques, Igor,Fé,lix, Ví,tor,Namkung, Wan Nature Publishing Group 2017 Nature chemistry Vol.9 No.7

<P>Perturbations in cellular chloride concentrations can affect cellular pH and autophagy and lead to the onset of apoptosis. With this in mind, synthetic ion transporters have been used to disturb cellular ion homeostasis and thereby induce cell death; however, it is not clear whether synthetic ion transporters can also be used to disrupt autophagy. Here, we show that squaramide-based ion transporters enhance the transport of chloride anions in liposomal models and promote sodium chloride influx into the cytosol. Liposomal and cellular transport activity of the squaramides is shown to correlate with cell death activity, which is attributed to caspase-dependent apoptosis. One ion transporter was also shown to cause additional changes in lysosomal pH, which leads to impairment of lysosomal enzyme activity and disruption of autophagic processes. This disruption is independent of the initiation of apoptosis by the ion transporter. This study provides the first experimental evidence that synthetic ion transporters can disrupt both autophagy and induce apoptosis.</P>