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This study conducts a numerical comparison of the thermal performance of three distinct working fluids (pure water, TiO2, and SiO2 water-based nanofluids) within an evacuated tube solar collector using Computational Fluid Dynamics. The study evaluates thermohydraulic performance alongside global and local entropy generation rates, while considering variations in solar radiation values and inlet mass flow rates. Results indicate that nanofluids demonstrate superior performance under low solar radiation, exhibiting higher outlet temperatures, velocities, thermal efficiency, and exergy efficiency compared to pure water. However, at the higher solar radiation level, the efficiency of SiO2 water-based nanofluid diminishes due to its impact on specific heat. Furthermore, the entropy generation analysis reveals significant reductions with TiO2 water-based nanofluid in all the phenomena considered (up to 79 %). The SiO2 nanofluid performance aligns closely with pure water under high radiation value. This investigation offers valuable insights into the utilization of nanofluids in solar collectors across diverse operating conditions, emphasizing their pivotal role in enhancing overall performance.

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In this work, a numerical analysis of three different flat plate solar collectors was conducted using their entropy generation rates. Specifically, the Computational Fluid Dynamics (CFD) technique was used to compare the detailed performance of conventional and zigzag tube geometries of flat plate solar collectors (FPCs) in terms of their entropy generation rates. The effects of fluid viscosity, heat transfer, and heat loss of the flat plate solar collectors were considered for the local and global entropy generation rate analyses. Variations on the inlet volumetric flow rate of the FPCs from 1.0 to 9.0 L/min were simulated under the average solar radiation for one year in the state of Guanajuato, Mexico. The results illustrate and discuss the temperatures, pressures, and global entropy generation rates for volumetric flow variations. The velocity, temperature, and pressure distributions and the maps of the local entropy generation rates inside the collectors are presented and analyzed for the case with a flow rate of 3.0 L/min. These results demonstrate that the zigzag geometries achieved higher outlet temperatures and greater entropy generation rates than the conventional geometry for all the volumetric flow rates considered.

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INTRODUCTION AND AIM: Transnasal endoscopy (TNE) has proven its diagnostic utility, but it has not been widely accepted given that it is performed without sedation. There are no previous studies on the use of methods to improve its tolerability. Our aim was to evaluate the tolerability of TNE, when simultaneously performed with an audiovisual device as a distractor. METHODS: We evaluated 50 patients, 10 of whom did not agree to participate. The performance of the procedure was explained, using an audiovisual device. Before randomization, we applied anxiety and depression scores. Patients were divided into 2 groups: Group I (using an audiovisual device during the procedure) and Group II (without a device). Anxiety and numeric pain rating scales were used, and vital signs were monitored and recorded before, during, and after the endoscopy. An overall procedure satisfaction score was applied at the end of the study and 24 h later. RESULTS: Mean age was 41.6 years and 35 of the patients were women (87.5%). The most frequent indication for TNE was refractory gastroesophageal reflux disease. There were no severe comorbidities, and none of the patients had a significant anxiety or depression score. One patient in Group II did not tolerate TNE due to nasal pain. There was no statistically significant difference between groups, regarding anxiety, pain, vital signs, and satisfaction scale. CONCLUSION: Our study showed that TNE was well tolerated and had a high acceptance rate in our patients. The use of distracting audiovisual devices did not increase tolerance to the endoscopic procedure.

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El objetivo de este trabajo fue obtener la frecuencia de los diferentes biotipos faciales que presentan los pacientes del Post Grado de Ortodoncia de la Universidad Autónoma del Paraguay desde el año 2009 al 2017. Metodología: se utilizó una planilla para el levantamiento de los datos proporcionados por fichas clínicas de los pacientes del Postgrado de Ortodoncia, se diseñó según correspondían a la denominación dolicofacial severo, dólicofacial, dólicofacial suave, mesofacial, braquifacial y braquifa-cial severo, determinados previamente por el estudio y análisis de 5 factores de Ricketts. Las variables de interés fueron, bioti-po facial, género y año en el cual fueron fichados los pacientes. Resultados y Conclusión: Luego de corroborar los resultados obtenidos de los diferentes biotipos faciales, se logra obtener la frecuencia de los mismos, siendo pacientes mesofaciales 30% de la población, seguido de braquifaciales 19%, braquifaciales severos y dólico suave 15 % cada uno, dólico faciales 13% y por último los pacientes que en menor frecuencia se presentaron, dólico severos 4% de la población.

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OBJECTIVE: Post-thrombotic syndrome (PTS) is the long-term sequelae of deep venous thrombosis (DVT). PTS clinical manifestations include chronic leg pain, oedema, lipodermatosclerosis and ulcers. The objective of this study is to determine in patients with documented history of thrombophilias and DVT whether the number of previous thrombotic events and optimal anticoagulation therapy are associated with the time to venous ulcer healing following the start of compression therapy. METHOD: Retrospective analysis performed in thrombophilic patients under the age of 50 years old with chronic venous ulcers secondary to DVT at the wound clinic in the National Institute of Medical Sciences and Nutrition 'Salvador Zubirán ' in Mexico City. Variables such as the number or episodes of thrombotic events, type of hypercoagulable disorder, optimal anticoagulation therapy with Warfarin monitored by therapeutic International Normalised Ratio (INR) (2-3) and compliance to compression therapy were examined. Patients that underwent superficial or perforator vein interruption or endovascular recanalisation of deep veins were excluded from the study. RESULTS: From a database of 29 patients with chronic venous ulcers followed in our clinic from January 1992 to September 2012, only 13 patients (61% female) met the inclusion criteria. Mean age±standard deviation (SD) was 32±12 years old. Of these, seven (54%) patients with suboptimal INR presented with an average of two previous thrombotic events and the remaining six (46%) patients with optimal INR only one event (p=0.28), the mean time to the clinical manifestation of a venous ulcer after the first episode of DVT was 39 months (range: 12-72) for patients with suboptimal INR and 82 months (range: 12-216) for those with optimal anticoagulation therapy (p=0.11). During the mean follow-up period of 52 months, all patients in optimal anticoagulation healed their ulcer; their mean time for wound healing was 44 months (range: 4-102). In the suboptimal INR group, only four healed the ulcers with an mean of 72 months (range: 2-204) (p=0.94). CONCLUSION: There seems to be an association between an optimal anticoagulation therapy with Warfarin monitored by INR and wound healing rates in thrombophilic patients with chronic venous ulcers. Further research is warranted. DECLARATION OF INTEREST: The authors have no conflict of interest.

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The basic food basket (BFB), formed by the more economical products available, is used by less-affluent countries to establish the minimum daily food consumption to satisfy nutritional requirements in less-privileged individuals. There is no information about groups that depend on the BFB and in addition follow gluten-free diet (GF/BFB). We measured availability, cost, main ingredients and nutritional composition of GF/BFB. Data were collected in the area that was first in the social priority list in the capital city, matching BFB components with gluten-free equivalents (GF/BFB). GF/BFB characterized by being 42% less available, three times more costly (>500% higher for bread), with up to 69% lower protein content and with no fortifications, leaving at nutritional risk celiac individuals that depend on GF/BFB. Results raise concerns on the capacity of the GF/BFB to encourage adherence, maintain adequate nutritional status and quality of life in celiac patients.

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Objetivo: Describir nivel de conocimiento, actitud y práctica de medidas básicas de prevención en salud oral en odontólogos que asistieron al VI Congreso Paraguayo de Endodoncia en el año 2011.Metodología: Estudio transversal, a través de una encuesta autoaplicada validada que contenía preguntas básicas referentes a Odontología Preventiva. Resultados: Participaron del estudio 173 profesionales, con una mediana de 33 años,62,4% con 1 a 12 años de ejercicio en la profesión y 58,4% procedían de universidades públicas.El 57,8% de los encuestados demostró tener muy buenos niveles de conocimiento,de actitud en el 46,8%y38,2%en práctica.La aplicación de medidas de prevención produjo en el 64,2% de los encuestados satisfacción personal. Respecto a las medidas de control de placa, las técnicas más difundidas fueron:cepillado de Bass 80,4%,método del lazo para el hilo dental 53,8% y el flúor se aplica en el 76,9% en su presentación de enjuagues bucales. Se encontró una fuerte asociación entre el conocimiento y la actitud (OR=4,3;p<0,0001) y entre la actitud y la práctica (OR=2,3;p=0,0162) Conclusión: La práctica de la filosofía preventiva se halla condicionada por la actitud y ésta a su vez depende del conocimiento constituyéndose componentes esenciales para la mejora del estado de salud de una población. Palabras claves: Conocimiento, Odontología Preventiva, Odontólogos.

Objective: To describe the level of knowledge, attitude and practice of basic preventive measures in oral health acquired by dentists who attended the VI Paraguayan Congress of Endodontics in 2011. Methods: Cross-sectional study by a validated self-administered survey containing basic questions regarding to Preventive Dentistry. Results: The study comprised 173 professionals, with an average age of 33 years old, 62.4 % with 1-12 years of practice in the profession and almost 58.4 % were from public universities. Whatsmore, 57.8 % of respondents proved to have very good levels of knowledge, 46.8 % of them proved it in attitude and 38.2 % in practice. The application of preventive measures gave to 64.2% of respondents a personal satisfaction. Concerning plaque control measures, the most widely used techniques were: 80.4 % Bass brushing, 53.8 % in a method to tie dental floss and fluoride applies to 76.9% in its presentation of rinses mouth. Furthermore, it has been found a strong association between attitude and practice (OR = 2.3, p = 0.0162) and between knowledge and attitude (p < 0.0001 OR = 4.3) Conclusion: the practice of prevention philosophy is based on the attitude and this in turn depends on knowledge. Therefore, attitude and knowledge are essential components in order to improve the health status of a population. Keywords: Knowledge, Preventive Dentistry, Dental.

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BACKGROUND AND STUDY AIMS: In patients with gastroesophageal reflux disease (GERD), temporary electrical stimulation of the lower esophageal sphincter (LES) increases LES pressure without interference with LES relaxation. The aim of the current study was to investigate the safety and efficacy of long term LES electrical stimulation therapy (LES-EST), using a permanently implanted stimulator for the treatment of GERD. PATIENTS AND METHODS: Patients with GERD who were at least partially responsive to proton pump inhibitors (PPIs) and who had hiatal hernia of ≤ 3 cm and esophagitis of Los Angeles Grade A, B, or C were included in the study. Stimulation electrodes were placed in the LES and a pulse generator (EndoStim LES Stimulation System; EndoStim BV, The Hague, The Netherlands) was implanted laparoscopically. LES stimulation was delivered at 20 Hz, 215 µs, 3 - 8 mA in multiple 30-minute sessions. Patients were evaluated at follow-up using the GERD Health-Related Quality of Life (HRQL) questionnaire, daily symptom and medication diaries, the SF-12 Health Survey, esophageal pH testing, and high resolution manometry. RESULTS: A total of 24 patients (mean age 53 ± 12 years; 14 men) were implanted and 23 completed the 12-month evaluation. No serious implantation or stimulation-related adverse affects or sensations were reported. Median composite GERD-HRQL score at 12 months was 2.0 (interquartile range [IQR] 0 - 3.0), which was significantly better than baseline scores both on PPI therapy (median 9.0, IQR 6.0 - 10.0; P = 0.002) and off PPIs (median 23.5, IQR 21 - 25.75; P < 0.001). The median percentage of the 24-hour period with esophageal pH < 4.0 at baseline was 10.1 % (IQR 7.7 - 15.5), which was reduced to 3.3 % (1.8 - 6.9) at 12 months (P < 0.001), with 69 % of patients showing either normalization or > 50 % improvement in their distal esophageal pH. At 12 months, 96 % of patients (22/23) were completely off PPI medication. CONCLUSION: During the long term follow-up of 12 months, LES - EST was safe and effective for the treatment of GERD. There was a significant and sustained improvement in GERD symptoms, reduction in esophageal acid exposure with elimination of daily PPI usage, and no stimulation-related adverse effects.

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BACKGROUND: Electrical stimulation (ES) of the lower esophageal sphincter (LES) increases resting LES pressure (LESP) in animal models. Our aims were to evaluate the safety of such stimulation in humans, and test the hypothesis that ES increases resting LESP in patients with gastroesophageal reflux disease (GERD). METHODS: A total of 10 subjects (nine female patients, mean age 52.6 years), with symptoms of GERD responsive to PPIs, low resting LES pressure, and abnormal 24-h intraesophageal pH test were enrolled. Those with hiatal hernia >2 cm and/or esophagitis >Los Angeles Grade B were excluded. Bipolar stitch electrodes were placed longitudinally in the LES during an elective laparoscopic cholecystectomy, secured by a clip and exteriorized through the abdominal wall. Following recovery, an external pulse generator delivered two types of stimulation for periods of 30 min: (i) low energy stimulation; pulse width of 200 µs, frequency of 20 Hz and current of 5-15 mA (current was increased up to 15 mA if LESP was less than 15 mmHg), and (ii) high energy stimulation; pulse width of 375 ms, frequency of 6 cpm, and current 5 mA. Resting LESP, amplitude of esophageal contractions and residual LESP in response to swallows were assessed before and after stimulation. Symptoms of chest pain, abdominal pain, and dysphagia were recorded before, during, and after stimulation and 7-days after stimulation. Continuous cardiac monitoring was performed during and after stimulation. KEY RESULTS: All patients were successfully implanted nine subjects received high frequency, low energy, and four subjects received low frequency, high energy stimulation. Both types of stimulation significantly increased resting LESP: from 8.6 mmHg (95% CI 4.1-13.1) to 16.6 mmHg (95% CI 10.8-19.2), P < 0.001 with low energy stimulation and from 9.2 mmHg (95% CI 2.0-16.3) to 16.5 mmHg (95% CI 2.7-30.1), P = 0.03 with high energy stimulation. Neither type of stimulation affected the amplitude of esophageal peristalsis or residual LESP. No subject complained of dysphagia. One subject had retrosternal discomfort with stimulation at 15 mA that was not experienced with stimulation at 13 mA. There were no adverse events or any cardiac rhythm abnormalities with either type of stimulation. CONCLUSIONS & INFERENCES: Short-term stimulation of the LES in patients with GERD significantly increases resting LESP without affecting esophageal peristalsis or LES relaxation. Electrical stimulation of the LES may offer a novel therapy for patients with GERD.

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