Study of the Scattering Effect by SiO2 Nanoparticles, in a Luminescent Solar Concentrator Sensitized with Carbon Dots.

Luminescent solar concentrators (LSCs) have become an attractive way to produce green energy via their integration into buildings as photovoltaic windows. Recently, carbon quantum dots (C-QDs) have become the most studied luminescent material for the manufacture of luminescent solar concentrators due to their advantages, such as low toxicity, sustainability, and low cost. Despite the advantages of carbon quantum dots, they remain a low-efficiency material, and it is difficult to fabricate LSCs with a good performance. To address this problem, some of the research has used SiO2 nanoparticles (Nps) to produce a light-scattering effect that helps to improve the system performance. However, these studies are limited and have not been discussed in detail. In this regard, this research work was designed to evaluate the contribution of the scattering effect in different systems of carbon quantum dots used in a possible luminescent solar concentrator. To carry out this study, C-QDs and SiO2 Nps were synthesized by hydrothermal methods and the Stober method, respectively. We used different concentrations of both materials to fabricate film LSCs (10 × 10 cm2). The results show that the light scattered by the SiO2 Nps has a double contribution, in terms of light redirected towards the edges of the window and as a secondary source of excitation for the C-QDs; thus, an improvement in the performance of the LSC is achieved. The best improvement in photoluminescence is achieved when the films are composed of 20% wt carbon quantum dots and 10% wt SiO2 Nps, reaching a gain of 16% of the intensity of the light incident on the edges of the window with respect to the LSCs where only C-QDs were used.

Modeling and Optimization of the Adsorption of Cr (VI) in a Chitosan-Resole Aerogel Using Response Surface Methodology.

In this paper, a model for Cr (VI) removal and optimization was made using a novel aerogel material, chitosan-resole CS/R aerogel, where a freeze-drying and final thermal treatment was employed to fabricate the aerogel. This processing ensures a network structure and stability for the CS, despite the non-uniform ice growth promoted by this process. Morphological analysis indicated a successful aerogel elaboration process., FTIR spectroscopy corroborated the aerogel precursor's identity and ascertained chemical bonding after adsorption. Owing to the variability of formulations, the adsorption capacity was modeled and optimized using computational techniques. The response surface methodology (RSM), based on the Box-Behnken design using three levels, was used to calculate the best control parameters for the CS/R aerogel: the concentration at %vol (50-90%), the initial concentration of Cr (VI) (25-100 mg/L), and adsorption time (0.3-4 h). Analysis of variance (ANOVA) and 3D graphs reveal that the CS/R aerogel concentration and adsorption time are the main parameters that influence the initial concentration of CS/R aerogel metal-ion uptake. The developed model successfully describes the process with a correlation coefficient of R2 = 0.96 for the RSM. The model obtained was optimized to find the best material design proposal for Cr (VI) removal. Numerical optimization was used and showed superior Cr (VI) removal (94.4%) under conditions of a CS/R aerogel concentration of 87/13 %vol, with an initial concentration of Cr (VI) of 31 mg/L, and an adsorption time of 3.02 h. These results suggest that the proposed computational model can obtain an effective and viable model for CS material processing and for optimization of the uptake of this metal.

Physical activity, balance, and bicycling in older adults.

Falls are a critical public health issue among older adults. One notable factor contributing to falls in older adults is a deterioration of the structures supporting balance and overall balance control. Preliminary evidence suggests older adults who ride a bicycle have better balance than those who do not. Cycling may be an effective intervention to prevent falls among older adults. This study aims to objectively measure the relationship between bicycling, physical activity, and balance for older adults. Older adult cyclists (n = 19) and non-cyclists (n = 27) were recruited to (1) complete a survey that assessed demographics; (2) wear an accelerometer for 3 weeks to objectively assess physical activity; and (3) complete balance-related tasks on force platforms. Mann-Whitney U-tests were performed to detect differences in balance and physical activity metrics between cyclists and non-cyclists. Cyclists were significantly more physically active than non-cyclists. Cyclists, compared to non-cyclists, exhibited differences in balance-related temporospatial metrics and long-range temporal correlations that suggest a more tightly regulated postural control strategy that may relate to higher stability. Cycling was observed to correlate more strongly with balance outcomes than other physical activity. Taken together, these results demonstrate the possible implications for cycling as an effective intervention to improve balance and reduce fall risk.

Portable sauna stimulated-diaphoresis for the treatment of fluid-overload in peritoneal dialysis patients: A pilot study.

Background: Fluid overload (FO) is a common problem in patients with peritoneal dialysis (PD), it is associated with adverse outcomes and may persist despite adjustements in PD therapy. Objective: To evaluate the feasibility and safety of stimulated diaphoresis to reduce FO with the use of a portable sauna bath. Methods: Open-label pilot study in patients on continuous ambulatory peritoneal dialysis (CAPD) and FO. The primary outcome was the treatment-related adverse events; secondary outcomes were changes in over-hydration (OH), body weight and blood pressure, FO symptoms, and sleep quality. Dialysis prescription and daily data were recorded. The intervention period consisted in a 30-min, 45°C sauna bath, daily for 10 days, using a portable sauna bath. Results: Fifty-one out of 54 total sauna bath sessions were well tolerated. In three (5.5%) sessions adverse effects were reported: transient dizziness in two cases, and a second-degree skin burn in a patient with advanced diabetic neuropathy. OH (6.3 ± 1.2 L vs. 5.5 ± 1.3 L, p = 0.05), body weight (67.7 ± 11.4 vs. 66.8 ± 3.8 kg, p = 0.003), diastolic blood pressure (92 ± 13.5 vs. 83 ± 13.3 mmHg, P = 0.003) and PSQI score (7.3 ± 3.7 vs. 5.1 ± 3.2, p = 0.02) improved significantly between the control and intervention period, respectively. Conclusions: Stimulated diaphoresis with a portable sauna bath could be a novel, safe, and effective alternative way to reduce FO in CAPD patients. Larger studies are needed to confirm our results. Clinical trial registration: ClinicalTrials.gov, identifier: NCT03563898.

Rectus abdominis muscle thickness as a predictor of peritoneal catheter dysfunction in emergency-start peritoneal dialysis patients.

BACKGROUND: Percutaneous insertion of a peritoneal dialysis catheter (PDc) is an alternative to open surgical techniques, and the anatomical characteristics of the abdominal wall may predict PDc dysfunction. We evaluated the role of rectus abdominis muscle (RAM) thickness as a predictor of PDc dysfunction. MATERIALS AND METHODS: A prospective cohort of emergency-start PD patients (EmPD) who had their first percutaneous PDc insertion were included. PDc failure was defined as the removal of a PDc due to mechanical failure within the first 30 PD fluid exchanges. Clinical variables were recorded. The skin to parietal peritoneum depth and RAM thickness were determined by abdominal ultrasound. Univariate and multivariate logistic regression models were developed to test associations between clinical parameters and PDc dysfunction. RESULTS: Over 6 months, 119 patients underwent PDc insertion; 73 (61.3%) were males, with a mean age of 46.0 ± 17.8 years. The mean skin-to-peritoneum depth was 2.5 ± 1.0 cm, the RAM thickness was 0.91 ± 0.3 cm, and catheter implantation was successful in 116 (97.4%) patients. Insertion failed in 3 (2.5%) cases, and 30 (25.8%) patients presented with catheter dysfunction. Univariate analysis indicated that RAM thickness ≥ 1.0 cm, skin-to-peritoneum depth > 2.88 cm, abdominal waist > 92.5 cm, and skin-to-RAM fascia distance > 2.3 cm were associated with PDc dysfunction; in multivariate logistic regression analysis, only greater RAM thickness remained a significant predictor (OR 1.6, 95% CI 1.38 - 1.88, p < 0.001). CONCLUSION: In EmPD patients, RAM thickness is associated with PDc dysfunction and could aid in identifying patients at risk for PDc dysfunction in emergency settings. Additional adequately powered studies are needed to confirm our findings.

El Quigong en la intervención de la depresión, la ansiedad, y el estrés psicológico laboral / The Quigong in the intervention of depression, anxiety, and psychological stress at work

El impacto de los dramáticos cambios multidimensionales ocasionado por la globalización genera un proceso histórico crítico que impacta al tejido social, sometiendo a muchas poblaciones, a un deterioro de su calidad de vida y de sus posibilidades de acceso a la atención sanitaria. Asimismo están expuestos a tensiones crónicas que pueden desbordar las capacidades y mecanismos de adaptación de las personas. La Medicina Tradicional China tiene más de 5.000 años de práctica empírica y abarca cinco componentes: fitoterapia, dietética, masajes, acupuntura y el Quigong. Su rol terapéutico ha sido reconocido por la OMS, quien ha diseñado estrategias para promover su integración al sistema sanitario de todos los países. Se eligió el componente Quigong para revisar trabajos científicos donde se implementaron sus prácticas en el tratamiento de la Depresión, la Ansiedad y el Estrés psicológico laboral. Los resultados de los estudios revisados concluyeron que existen evidencias significativas de que el Quigong puede mejorar la clínica de pacientes con diagnóstico de Depresión, Ansiedad y estrés laboral. Asimismo, los autores de los trabajos realizados coinciden en la necesidad de proseguir la línea de investigación relativa a las aplicaciones del Quigong como terapia preventiva y curativa en estrés psicológico, ansiedad y depresión.

The impact of the dramatic multidimensional changes caused by globalization generates a critical historical process that impacts the social fabric, subjecting many populations to a deterioration in their quality of life and their possibilities of access to health care. They are also exposed to chronic tensions that can overwhelm people's capacities and adaptation mechanisms. Traditional Chinese Medicine has more than 5.000 years of empirical practice and includes five components: phytotherapy, dietetics, massage, acupuncture and Quigong. Its therapeutic role has been recognized by the WHO, which has designed strategies to promote its integration into the health system of all countries. The Quigong component was chosen to review scientific works where its practices were implemented in the treatment of Depression, Anxiety and Occupational Psychological Stress. The results of the studies reviewed concluded that there is significant evidence that Quigong can improve the clinic of patients diagnosed with Depression, Anxiety, and occupational stress. Likewise, the authors of the works carried out agree on the need to continue the line of research regarding the applications of Quigong as preventive and curative therapy in psychological stress, anxiety and depression.

Polydimethylsiloxane nanocomposite macroporous films prepared via Pickering high internal phase emulsions as effective dielectrics for enhancing the performance of triboelectric nanogenerators.

Polydimethylsiloxane (PDMS) nanocomposite (NC) macroporous films were prepared by a Pickering high internal phase emulsion (HIPE) templating technique and used as effective dielectrics for enhancing the performance of triboelectric-nanogenerators (TENGs). HIPEs were formulated using commercial PDMS and water as the continuous and dispersed phase, respectively. The formation and solidification of PDMS-based HIPEs were possible through stabilization with silver-nanoparticles (Ag-Nps) and surfactant (Span 20) mixtures. The resulting PDMS-NC-polyHIPE films presented an interconnected 3D macroporous structure with Ag-Nps on their porous surface. The addition of different amounts of Ag-Nps (0, 4, 20, 28, 36 wt%) in HIPE formulations allowed modification of the pore size, total pore volume and dielectric properties of the tribo-materials. Results revealed that both the porosity and dielectric properties of these materials play an important role in enhancing the output performance of TENGs. Thus, the best TENG based on the PDMS-NC-polyHIPE film was achieved with 20 wt% of Ag-Nps, with voltage, current and power values of 4.88 V, 0.433 µA and 2.1 µW, respectively, which gives over 3.28-fold power enhancement compared with the reference TENG (based on a PDMS film without porosity or Ag-Nps). Therefore, the preparation of tribo-materials through a Pickering HIPE templating technique provides a novel, effective and easy way for the improvement of the TENG's performance.

Fast back-projection for non-line of sight reconstruction.

Recent works have demonstrated non-line of sight (NLOS) reconstruction by using the time-resolved signal from multiply scattered light. These works combine ultrafast imaging systems with computation, which back-projects the recorded space-time signal to build a probabilistic map of the hidden geometry. Unfortunately, this computation is slow, becoming a bottleneck as the imaging technology improves. In this work, we propose a new back-projection technique for NLOS reconstruction, which is up to a thousand times faster than previous work, with almost no quality loss. We base on the observation that the hidden geometry probability map can be built as the intersection of the three-bounce space-time manifolds defined by the light illuminating the hidden geometry and the visible point receiving the scattered light from such hidden geometry. This allows us to pose the reconstruction of the hidden geometry as the voxelization of these space-time manifolds, which has lower theoretic complexity and is easily implementable in the GPU. We demonstrate the efficiency and quality of our technique compared against previous methods in both captured and synthetic data.

Evaluación de la calidad del agua y su tendencia corrosiva en los morichales Guaricongo y Los Caribes, municipio Heres, Ciudad Bolívar, estado Bolívar, Venezuela / Evaluation of the quality of the water and its corrosive trend in the morichales Guaricongo and Los Caribes, Heres municipality, Ciudad Bolívar, Bolívar state, Venezuela

El presente trabajo consistió en evaluar los niveles de calidad del agua y su tendencia corrosiva en los morichales “Guaricongo” y “Los Caribes”, Municipio Heres, Ciudad Bolívar, estado Bolívar. Se tomaron muestras de agua en cada subcuenca de estudio y en la confluencia de las mismas. Se determinaron parámetros fisicoquímicos (temperatura, pH, oxígeno disuelto, sólidos totales y disueltos, demanda bioquímica de oxígeno, demanda química de oxígeno, dureza total, alcalinidad, calcio, magnesio, nitratos, sulfatos y cloruros), a partir de esta data se calcularon los índices de corrosión e incrustación de Langelier (IL), Potencial de Precipitación (PPCC), Ryznar (IR), Agresividad (IA), Larson (RL), Singley, Capacidad Buffer, Snoeyink. Los resultados indican que las aguas de estos morichales presentaron pH ligeramente ácido, levemente duras indicativos de aguas agresivas con tendencia corrosiva, lo cual fue corroborado a través de los índices de corrosión calculados, clasificando a estas aguas como insaturadas, con preferencia a disolver el CaCO3 indicativo de un carácter corrosivo.

The present work was to evaluate the levels of water quality and its corrosive trend in "morichales" "Guaricongo" and "Caribbean" Heres municipality, Ciudad Bolivar, Bolivar State. Water samples were taken in each subwatershed study and at the confluence of the same. Physicochemical parameters were determined (temperature, pH, dissolved oxygen, total and dissolved solids, biochemical oxygen demand, chemical oxygen demand, total hardness, alkalinity, calcium, magnesium, nitrates, sulfates and chlorides). From this data rates of corrosion and scaling of Langelier (IL), Precipitation Potential (PPCC),m Ryznar (IR), Aggression (IA), Larson (RL), Singley, Buffer Capacity, Snoeyink were calculated. The results indicate that the waters of these "morichales" were slightly acidic and slightly hard water, indicative of an aggressive corrosive tendency, which was corroborated by the corrosion rates calculated by classifying these waters as unsaturated, preferably to dissolve the CaCO3 indicative of a corrosive nature.

Risk of peritonitis among disadvantaged CAPD patients in Mexico.

BACKGROUND/AIMS: Continuous ambulatory peritoneal dialysis is the first-choice treatment for ESRD in Mexico. Peritonitis is the most frequent cause of morbidity and is among the leading causes of technique failure in our country. Our objective was to compare the efficacy of the standard and double-bag disconnect systems for the prevention of peritonitis in a high-risk population with poor living standards, and high prevalence of malnutrition and diabetes rates. METHODS: Episodes of peritonitis registered between July 1989 and June 2003 were included. Patients were divided in conventional and double-bag groups. Between July 1989 and May 1999, all patients used the conventional system. From May 1999, all incident patients were placed on a double-bag disconnect system. RESULTS: Six-hundred and forty-seven patients started dialysis in the study period, 383 in the conventional group, and 264 in the double-bag. The peritonitis rate observed was 1 episode per 7.2 patient-months in the conventional group, and 1 episode per 25.1 patient-months in the double-bag system (p < 0.001). Cumulative peritonitis-free survival rate at 6 (50 vs. 82%), 12 (27 vs. 69%) and 24 (12 vs. 45%) months, respectively, was significantly lower in the conventional group (p < 0.001). Technique survival at 1 (75 vs. 85%), 2 (68 vs. 80%), and 3 years (50 vs. 80%), was worse in the conventional group (p < 0.001). By multivariate analysis, the only factor associated with peritonitis was the connecting system. CONCLUSIONS: We conclude that switching from a standard to a double-bag system using electrolytically produced sodium hypochlorite disinfectant markedly decreased the peritonitis rate, even in a high-risk population like ours.

Cardiovascular risk factors in the Mexican population.

Chronic degenerative disorders have become a major health problem in Mexico. Cardiovascular diseases represent the first cause of death in our country. Diabetes mellitus (DM) has emerged as the main health problem in Mexico. Its prevalence doubled from < 3% in the 1960s to 6% in the 1980s. Between 1993 and 2000, diabetes mellitus increased from 6.7% to 8.2%, a 22% growth over a seven-year period. In 1995, the cost of the treatment of DM represented 15.48% of the health budget and 0.79% of the GDP. The prevalence of hypertension (HTN) increased from 10% in 1933 to 20% in 1990 and from 23.8% to 30.7% between 1993 and 2000. The expenditures from HTN in 1999 corresponded to 13.9% of the health budget, and 0.71% of GDP. Dyslipidemias are very common. Close to 40% of the population has levels of HDL cholesterol < 35 mg/dL, 24.3% has fasting triglycerides > 200 mg/dL, and 10% has hypercholesterolemia. The prevalence of obesity increased from 21.4% in 1993, to 23.7% in the year 2000. Eight percent of the population has a glomerular filtration rate < 60 mL/min, and 9.1% has proteinuria. Twenty-four percent uses tobacco regularly, and 13% had the habit in the past. Smoking is more frequent among diabetics (34%).In conclusion, cardiovascular risks factors are highly common among the Mexican population and increasing at alarming rates. Preventive programs targeted to decrease their prevalence are urgently needed in Mexico and should become a national priority.

Is renal replacement therapy for all possible in developing countries?

Chronic kidney disease is a worldwide public health problem. More than one million individuals in the world are on maintenance dialysis, a number that is estimated to double in the next decade. Access to dialysis is significantly different between developed and developing nations. Close to 80% of the world dialysis population is treated in Europe, North America, and Japan, representing 12% of the world's population. The remaining dialysis patients are treated in the developing world. This disparity is likely due to the high cost and complexity of renal replacement therapy (RRT). Dialysis is so costly that is out of reach for low-income countries, which are struggling to provide preventive and therapeutic measures for communicable diseases and other basic needs. Providing renal care to all developing nations, although a difficult task, is not impossible. A number of strategies are proposed. These include the prevention of kidney disease, as well as dialysis and transplantation. Dialysis programs should be decentralized, and kidney transplantation should be promoted as the treatment of choice. The use of generic immunosuppressive drugs can make this therapy more affordable. Peritoneal dialysis seems a good, affordable, therapy for patients living in areas where hemodialysis is not available. Governments should provide funds not only for RRT but also for the prevention of kidney failure. The provision of tax incentives and reaching a critical number of patients on RRT could be incentives for industry to lower the cost of dialysis. The challenges are enormous, but renal care for all could be achieved through a concerted effort between nephrologists, governments, patients, charitable organizations, and industry.

Diagnóstico del sistema de recolección de desechos generados en el Hospital Ruiz y Páez Ciudad Bolívar estado Bolívar Venezuela / Diagnosis of the medical waste management in the Ruiz y Páez Hospital Bolívar City Bolívar State Venezuela

El manejo inadecuado de los desechos sólidos procedentes de los centros hospitalarios, está considerado como uno de los principales factores de riesgo ocupacional, fundamentalmente por el carácter infeccioso de los desechos Tipo B y la presencia de objetos punzo-cortantes (Desechos Tipo C). Por ello, la presente investigación analítica y descriptiva, tiene como objetivo diagnosticar el manejo actual de los desechos generados en el Hospital Ruiz y Páez, estado Bolívar, Venezuela, mediante inspecciones realizadas en forma aleatoria a las diferentes áreas de servicio del hospital en referencia, la aplicación de una encuesta al personal de saneamiento y asistencial y la toma de fotografías. Se evidenció que no se cumple el 79,17% del Decreto 2.218 “Norma para la Clasificación y Manejo de Desechos en Establecimientos de Salud”, el 100% del personal asistencial y saneamiento encuestado, no ha recibido capacitación para el manejo de los desechos peligrosos e infecto-contagiosos. En el 2004-2005, se han registrado 31 accidentes laborales por objetos punzo cortantes. A partir de la información obtenida, se propone la necesidad de instituir un nuevo sistema de recolección y disposición final de los desechos generados. Para el establecimiento y consecución del sistema, se recomienda la incorporación y adiestramiento de toda la comunidad hospitalaria.

Valuación de corrosión e incrustraciones en instalaciones hidráulicas de una planta de potabilización en el estado Bolívar, Venezuela / Evaluation of corrosion and incrustations in the hydraulic installations of a water treatment plant in Bolívar State, Venezuela

En instalaciones hidráulicas se presenta corrosión en materiales metálicos (válvulas, bombas y tuberías), y en los elementos rígidos (concreto armado), al ser susceptibles al ataque destructivo considerado factor de importancia para la duración de la infraestructura. Dada esa situación, esta investigación tuvo como objetivo realizar una valuación de la corrosión e incrustaciones a las instalaciones hidráulicas de la planta de Potabilización “Angostura” Ciudad Bolívar, estado Bolívar. La investigación fue del tipo descriptiva y analítica, obteniéndose 16 fotos de los especímenes rígidos y metálicos con fallas de corrosión e incrustaciones, realizándose una descripción cualitativa. Los estados de corrosión e incrustaciones fueron determinados considerando los deterioros unitarios y probabilidades de operaciones de los especímenes metálicos y rígidos. La conclusión fue que los productos de corrosión observados en las superficies externas de los especímenes metálicosson causados por el medio atmosférico, agua (cruda, sedimentada y filtrada), reactivos químicos (sulfato de aluminio, cal hidratada y gas cloro) usados en el proceso. Los productos observados de reblandecimiento, desportillamiento y desintegración en especímenes de concreto armado son efectos multifactoriales de los procesos de: carbonatación, influencia del ión cloruro y oxidación biológica. El máximo deterioro unitario en los especímenes rígidos es 3,43% anual y en los especímenes metálicos es 3,26% anual. La probabilidad mayor de operación máxima para los elementos rígidos se ubica en 109,24 años y para los elementos metálicos se sitúa en 81,15 años.

Calidad y corrosión en aguas de las plantas de tratamiento Angostura y Guri del Estado Bolívar, Venezuela / Quality and corrosion in Angostura and Guri water treatment plants at Bolivar state, Venezuela

La presente investigación tuvo como propósito: determinar índices de calidad, caracterizar físicoquímicamente y bacteriológicamente y determinar índices de tendencias corrosivas (Langelier, Ryznar, Puckorius, Saturación y Tasa Singley) en muestras de aguas crudas y tratadas de los ríos Orinoco y Caroní, en las plantas de potabilización Angostura y Guri y de la red de distribución para los sectores: Las Flores, Medina Angarita, Paseo Gaspari, y Negro Primero de Ciudad Bolívar. La investigación fue de corte transversal, descriptivo y analítico. Las diferentes muestras de aguas analizadas presentan pH < 5, otros parámetros fisicoquímicos se encuentran por debajo de los valores de acuerdo a la norma vigente, se detectan coliformes totales en las muestras de aguas y los índices y tasa de corrosión reflejan una alta tendencia corrosiva. Se concluye que los índices de calidad de las aguas crudas son inadecuados. Se recomienda la caracterización fisicoquímica y bacteriológica para estanques de almacenamiento, redes de distribución para sectores residenciales, comerciales e industriales