Conversión de Oleum papaveris seminis en ésteres metílicos mediante un proceso de esterificación: Optimización y estudio cinético

This paper presents an acid pre-treatment process and a kinetic study for the esterification reaction of Oleum papaveris seminis oil with methanol in the presence of amberlite 120 as a solid catalyst to convert the oil into methyl esters. Response surface methodology (RSM) was applied to optimize the reaction parameters, i.e. reaction time, percentage of the catalyst and volume ratio of methanol to oil. The results revealed that 0.87% w/w of catalyst concentration and 44.70% v/v of methanol to oil ratio provided final free fatty acid (FFA) contents of 0.60% w/w at 102.40 min of reaction time. It proved that the contribution of Amberlite 120 in the esterification of FFA was highly significant. The kinetics of the esterification in Oleum papaveris seminis oil with methanol in the presence of the amberlite 120 catalyst were also investigated to establish the reaction rate constant (k), reaction order, and activation energy. The study was performed under the optimized parameters at three reaction temperatures (50, 55, and 60 ºC). The value of k was in the range of 0.013 to 0.027 min-1. The first-order kinetics’ model was suitable for this irreversible FFA esterification with the activation energy of about 60.9 KJ·mol-1.En este artículo se presenta un proceso de pre-tratamiento con ácido, y un estudio cinético de la reacción de esterificación. Se utiliza Oleum papaveris seminis con metanol en presencia de Amberlite 120 como catalizador sólido para la formación de los ésteres metílicos. Se aplicó una metodología de superficie de respuesta (RSM) para optimizar los parámetros de la reacción; es decir, tiempo de reacción, porcentaje de la relación de catalizador y volumen de metanol - aceite. Los resultados mostraron que el 0,87% w/w de la concentración de catalizador y 44,70% v/v de metanol en relación al aceite dan lugar a un contenido final de ácidos grasos libres (FFA) de 0,60% w/w en 102,40 min de tiempo de reacción. Se demostró que la contribución de Amberlite 120 en la esterificación de los FFA fue altamente significativa. La cinética de la esterificación del Oleum papaveris Seminis con metanol en presencia del catalizador Amberlite 120 también se investigó para establecer la constante de velocidad de reacción (k), orden de la reacción, y la energía de activación. El estudio se realizó bajo los parámetros optimizados a tres temperaturas de reacción (50, 55, y 60 °C). El valor de la constante k fué del rango de 0.013 a 0,027 min-1. El modelo de cinética de primer orden fue el adecuado para esta esterificación FFA irreversible con una energía de activación de aproximadamente 60,9 KJ mol -1

Micro-fabrication of Carbon Structures by Pattern Miniaturization in Resorcinol-Formaldehyde Gel

A simple and novel method to fabricate and miniaturize surface and sub-surface micro-structures and micro-patterns in glassy carbon is proposed and demonstrated. An aqueous resorcinol-formaldehyde (RF) sol is employed for micro-molding of the master-pattern to be replicated, followed by controlled drying and pyrolysis of the gel to reproduce an isotropically shrunk replica in carbon. The miniaturized version of the master-pattern thus replicated in carbon is about one order of magnitude smaller than original master by repeating three times the above cycle of molding and drying. The micro-fabrication method proposed will greatly enhance the toolbox for a facile fabrication of a variety of Carbon-MEMS and C-microfluidic devices.Comment: 16 pages, 5 figure

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

Background Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide.Methods A multimethods analysis was performed as part of the GlobalSurg 3 study-a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital.Findings Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3.85 [95% CI 2.58-5.75]; p<0.0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63.0% vs 82.7%; OR 0.35 [0.23-0.53]; p<0.0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer.Interpretation Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised

الدراسة المجهرية لبنكرياس الأرنب بعد قطع العصب الحائر

The microscopic study of the morphological changes in the rabbit pancreas were investigated after vagotomy. Structural changes were observed in the pancreatic acinar cells and in the islets of langerhans two and three weeks after vagotomy. Measurement of the fasting blood glucose level at different intervals of time post operatively and also the glucose tolerance test confirmed the structural changes of the islets of the pancreas after vagotomy.في هذه الدراسة المجهرية تم الكشف عن التغيرات الشكلية في بنكرياس الأرنب بعد قطع العصب الحائر. فقد تم ملاحظة التغيرات التركيبية في خلايا البنكرياس الكأسية ، وكذلك في جزر لانجرهانز بعد أسبوعين وثلاثة أسابيع من قطع العصب الحائر. ان قياس مستوى الجلوكوز في الدم لحيوانات التجارب الصائمة وعلى فترات مختلفة من عملية قطع العصب الحائر وكذلك قياس منحنى الجلوكوز التحملي في الدم لدليل يؤكد التغيرات التركيبية في جزر لانجرهانز بعد قطع العصب الحائر. ان نتائج هذه الدراسة تدُّل على ان البنكرياس يعتمد في تغذيته العصبية على العصب الحائر وان قطع العصب الحائر قد يؤدي الى العديد من اختلالات الأيض . هذه النتائج ايضا تفسر ان الاختلالات في نسبة الجلوكوز والانسولين والتي تحدث بعد عملية زرع البنكرياس هي غالبا ناتجة عن تآكل في الخلايا الصماء والتي تعزى الى قطع الأعصاب عن البنكرياس . على أي حال ان التغيرات التركيبية لأجزاء البنكرياس الصماء وغير الصماء الناتجة عن قطع العصب الحائر قد تفسر ان الضغط النفسي والصدمات العصبية في الإنسان قد تسبب امراض ومضاعفات في البنكرياس