Producción de Hidrógeno a partir de la fermentación de residuos agroindustriales de la piña

Hydrogen production from the fermentation of pineapple core wastes was studied using pretreated sludge from a local UASB wastewater treatment plant as inoculum. Applying a 23factorial design, the effects of initial substrate concentration, initial fermentation medium pH, and type of nutrient formulation on H2 production were studied. The best results were obtained at pH of 5,5, with a substrate concentration of 5 (g glucose)/L, and using a nutrient formulation based on magnesium, iron, zinc, and sodium. Then, utilizing the previous operating conditions, the fermentation was scaled up to a 5 L bioreactor and a maximum yield of 1,541 (mol H2)/(mol glucose) was achieved. This hydrogen yield is comparable with others reported in the literature when glucose was used as substrate. These results suggest that pineapple core wastes could be used as a renewable source for hydrogen productionSe estudió la generación de hidrógeno a partir de la fermentación anaeróbica de residuos agroindustriales de corazón de piña utilizando como inóculo lodos pretratados provenientes de una planta de tratamiento de agua residual del tipo UASB. Mediante un diseño factorial 23, se determinaron los efectos de la concentración inicial de sustrato, del pH inicial del medio de fermentación y de la formulación de nutrientes, sobre el rendimiento en la producción de hidrógeno. Los mejores resultados se obtuvieron utilizando un pH inicial de 5,5, con una concentración inicial de sustrato de 5 (g de glucosa)/L y usando una formulación de nutrientes basada en magnesio, hierro, zinc y sodio. Posteriormente, utilizando las condiciones de operación anteriores, se realizó un escalamiento de la fermentación en un bioreactor de 5 L y se alcanzó un rendimiento máximo en la producción de hidrógeno de 1,541 (mol H2)/(mol glucosa). Este rendimiento es comparable con datos reportados en la literatura cuando se ha usado glucosa como sustrato. Los resultados obtenidos sugieren que los residuos de corazón de piña podrían ser utilizados como una fuente renovable para la producción de hidrógen

Accelerated formation of hydrogen-producing granules for the start-up of UASB reactors using vinasses

Hydrogen-producing granules formation was studied in a CSTR. The aim of this process is to later transfer the mixed liquor to a UASB reactor to reduce its start-up period. Vinasses from a national bioetha­nol-producing industry (from sugar cane) were used as substrate and their anaerobic fermentation was carried out under mesophilic conditions. The seed sludge was collected from an UASB reactor oper­ated in an industrial wastewater treatment plant and it was heat treated to inactivate methanogenic bacteria. Total viable and non-viable material growth curves were generated and it was determined that the exponential growth phase of the thermally pre­treated mixed culture was between 20 and 120 h. Finally, the anaerobic fermentation of the vinasses in batch mode for 70 hours, and then in continuous CSTR mode for 7 days, showed to be an effective method for accelerating the formation of hydrogen-producing granules. Using this method, granules with an average size of 1.24 mm were achieved. The good efficiency of the process is attributed to high mass transfer in the CSTR reactor

Producción de hidrógeno a partir del tratamiento anaerobio de vinazas en un reactor UASB

Fermentative hydrogen production from sugar-cane vinasses was evaluated in a 3-L UASB reactor under mesophilic conditions. The seed sludge, taken from an industrial wastewater UASB reactor, was heat treated to inhibit non hydrogen producing bacteria. Hydrogen producing granules were first formed in a CSTR reactor and then transferred to the UASB reactor. Operating under mesophylic (37 °C) conditions, pH close to 5.5, inlet substrate concentration of 20 000 mg COD/L, and hydraulic retention time (HRT) of 6 hours, the average hydrogen production rate obtained in the UASB reactor was 1,68 mL H2/h/L, showing a maximum value of 13,4 mL H2/h/L. COD removal in the fermentation process reached maximum values of 43%, with an average value close to 20%. Both, hydrogen production and COD removal showed inverse dependence on HRT. The results obtained in this study show that anaerobic fermentation of vinasses using a UASB reactor is a feasible way to sustainably produce molecular hydrogen.Se evaluó la producción de hidrógeno mediante la fermentación anaerobia de vinazas generadas en la elaboración de etanol a partir de melazas de caña de azúcar. Esta evaluación se realizó a nivel de laboratorio, utilizando un reactor UASB de 3 L. Se emplearon los lodos de un reactor UASB de una planta de tratamiento de agua industrial para inocular el sistema productor de hidrógeno, después de someterlos a un tratamiento térmico para inhibir el crecimiento de bacterias metanogénicas. Los gránulos productores de hidrógeno se formaron primeramente en un reactor CSTR y luego se transfirieron al reactor UASB para iniciar su operación. Bajo condiciones mesofílicas (37 °C), un pH de operación de aproximadamente 5,50, una concentración del sustrato de 20 000 mg DQO/L y un tiempo de retención hidráulica (TRH) de seis horas, la producción promedio de hidrógeno obtenida en el reactor UASB fue de 1,68 mL H2/h/L, con una tasa máxima de 13,4 mL H2/h/L. El porcentaje de remoción de DQO en el proceso de fermentación alcanzó valores máximos del 43%, con un promedio cercano al 20%. Tanto la producción de hidrógeno como la remoción de DQO presentaron una dependencia inversamente proporcional al TRH. Los resultados obtenidos en este estudio demuestran que la fermentación anaerobia en un reactor UASB abre la posibilidad de utilizar las vinazas para producir hidrógeno molecular de forma sostenible.

Fotorreducción de dióxido de carbono usando TiO2 sensibilizado con trímeros de Co y Cu en medio acuoso

During this investigation, the performance of two titanium dioxide photocatalysts was evaluated in the photoreduction of carbon dioxide in aqueous media. One of the photocatalysts was sensitized with a copper trimer (Cu3(dpa)4Cl2) (dpa = 2.2´-dipyridylamine) and the other was sensitized with a cobalt trimer (Co3(dpa)4Cl2). Using a microwave reactor, the first experimental stage studied the TiO2 sensitization process, which occurs in two successive reactions: in the first one, the TiO2 surface is functionalized with p-Aminobenzoic acid (PABA) which acts as a binding molecule between TiO2 and the respective trimer, while in the second reaction, the metal trimer is anchored. Three levels of temperature, power output, and reaction time were analyzed for each of the two reactions; however, a Taguchi statistical analysis showed no significant differences between the treatments for the selected conditions. Therefore, it was determined that the photocatalyst sensitization process can be performed under the following conditions without affecting the final composition of each catalyst: 70 °C, 100 W, and 5 min in the functionalization stage with PABA and 80 °C, 150 W, and 5 min in the anchorage of the dyes. In the second experimental stage, the synthesized photocatalysts for CO2 photoreduction in aqueous medium was evaluated utilizing a medium-pressure ultraviolet lamp in a photoreactor at atmospheric pressure and at 25 °C. The catalyst with the best performance was the one sensitized with cobalt trimer since it showed a higher production of methane (14.28\ \sfrac{\mu mol}{g_{cat}\ h}), and carbon monoxide (32.84\sfrac{\mu mol}{g_{cat}\ h}). The copper sensitized catalyst showed no measurable generation of carbon monoxide, and the methane production was considerably lower (6.23\ µmolgcat h). Hydrogen production was important with both catalysts, particularly the catalyst sensitized with the copper trimer (420\ µmolgcat h). No presence of other CO2 reduction products was detected in the liquid phase.Na presente pesquisa foi avaliado o desempenho de dois fotocatalisadores de dióxido de titânio, um deles sensibilizado com um trímero de cobre (Cu3(dpa)4Cl2) (dpa = 2,2´-dipiridilamina) e o outro com um trímero de cobalto (Co3(dpa)4Cl2), especificamente, na fotorredução de dióxido de carbono em meio aquoso. Em uma primeira etapa experimental foi estudado o processo de sensibilização do TiO2, que ocorre em duas reações sucessivas utilizando um reator de micro-ondas: na primeira, a superfície do TiO2 é funcionalizada com ácido p-aminobenzóico (PABA) que age como molécula de ligação entre o TiO2 e o trímero respectivo; logo, na segunda reação, o trímero do metal é ancorado. Foram analisados três níveis de temperatura, potência e tempo de reação para cada uma das duas reações; não obstante, uma análise estatística robusta como o método Taguchi mostrou que não existe diferença significativa entre os tratamentos para as condições selecionadas. Como resultado disso, determinou-se que, para o processo de sensibilização dos fotocatalisadores, é possível trabalhar nas seguintes condições sem afetar a composição final de cada catalisador: 70 ºC, 100 W e 5 min na etapa de funcionalização com o PABA e 80 ºC, 150 W e 5 min na ancoragem de ambos os corantes. Na segunda etapa experimental foi realizada a avaliação dos fotocatalisadores sintetizados para a fotorredução de CO2 em meio aquoso, usando uma lâmpada ultravioleta de média pressão e um fotorreator sob pressão atmosférica e 25 ºC. O catalisador que apresentou melhor desempenho foi o sensibilizado com o trímero de cobalto, pois evidenciou maior produção de metano (14,28\ \sfrac{\mu mol}{g_{cat}\ h}) e monóxido de carbono (32,84\sfrac{\mu mol}{g_{cat}\ h}); por sua vez, o catalisador sensibilizado com cobre não apresentou geração quantificável de monóxido de carbono e a produção de metano foi consideravelmente menor (6,23\ µmolgcat h). A produção de hidrogênio por ambos os catalisadores foi importante, particularmente a do catalisador sensibilizado com o trímero de cobre (420\ µmolgcat h). Não houve detecção da presença de outros produtos oriundos da redução do CO2 na fase líquida.En la presente investigación, se evaluó el desempeño de dos fotocatalizadores de dióxido de titanio, uno sensibilizado con un trímero de cobre (Cu3(dpa)4Cl2) (dpa = 2,2´-dipiridilamina) y el otro con un trímero de cobalto (Co3(dpa)4Cl2), específicamente, en la fotorreducción de dióxido de carbono en medio acuoso. En una primera etapa experimental, se estudió el proceso de sensibilización del TiO2, el cual ocurre en dos reacciones sucesivas, utilizando un reactor de microondas: en la primera, se funcionaliza la superficie del TiO2 con ácido p-aminobenzoico (PABA) que actúa como molécula de enlace entre el TiO2 y el trímero respectivo; luego, en la segunda reacción, se ancla el trímero del metal. Se analizaron tres niveles de temperatura, potencia y tiempo de reacción para cada una de las dos reacciones; sin embargo, un análisis estadístico robusto tipo Taguchi arrojó que no existe diferencia significativa entre los tratamientos para las condiciones seleccionadas. Como resultado de esto, se determinó que para el proceso de sensibilización de los fotocatalizadores se puede trabajar en las siguientes condiciones sin afectar la composición final de cada catalizador: 70 ºC, 100 W y 5 min en la etapa de funcionalización con el PABA y 80 ºC, 150 W y 5 min en el anclaje de ambos tintes. En la segunda etapa experimental se realizó la evaluación de los fotocatalizadores sintetizados para la fotorreducción de CO2 en medio acuoso, empleando una lámpara ultravioleta de mediana presión y un fotorreactor a presión atmosférica y 25 ºC. El catalizador que presentó mejor desempeño fue el sensibilizado con el trímero de cobalto, ya que evidenció mayor producción de metano (14,28\ \sfrac{\mu mol}{g_{cat}\ h}) y monóxido de carbono (32,84\sfrac{\mu mol}{g_{cat}\ h}); por su parte, el catalizador sensibilizado con cobre no presentó generación cuantificable de monóxido de carbono y la producción de metano fue considerablemente menor (6,23\ µmolgcat h). La producción de hidrógeno por ambos catalizadores fue importante, particularmente, la del catalizador sensibilizado con el trímero de cobre (420\ µmolgcat h). No se detectó presencia de otros productos de la reducción del CO2 en la fase líquida

Delaying surgery for patients with a previous SARS-CoV-2 infection

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Optimization of adsorptive removal of α-toluic acid by CaO2 nanoparticles using response surface methodology

The present work addresses the optimization of process parameters for adsorptive removal of α-toluic acid by calcium peroxide (CaO2) nanoparticles using response surface methodology (RSM). CaO2 nanoparticles were synthesized by chemical precipitation method and confirmed by Transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) analysis which shows the CaO2 nanoparticles size range of 5–15 nm. A series of batch adsorption experiments were performed using CaO2 nanoparticles to remove α-toluic acid from the aqueous solution. Further, an experimental based central composite design (CCD) was developed to study the interactive effect of CaO2 adsorbent dosage, initial concentration of α-toluic acid, and contact time on α-toluic acid removal efficiency (response) and optimization of the process. Analysis of variance (ANOVA) was performed to determine the significance of the individual and the interactive effects of variables on the response. The model predicted response showed a good agreement with the experimental response, and the coefficient of determination, (R2) was 0.92. Among the variables, the interactive effect of adsorbent dosage and the initial α-toluic acid concentration was found to have more influence on the response than the contact time. Numerical optimization of process by RSM showed the optimal adsorbent dosage, initial concentration of α-toluic acid, and contact time as 0.03 g, 7.06 g/L, and 34 min respectively. The predicted removal efficiency was 99.50%. The experiments performed under these conditions showed α-toluic acid removal efficiency up to 98.05%, which confirmed the adequacy of the model prediction

The impact of surgical delay on resectability of colorectal cancer: An international prospective cohort study

AimThe SARS-CoV-2 pandemic has provided a unique opportunity to explore the impact of surgical delays on cancer resectability. This study aimed to compare resectability for colorectal cancer patients undergoing delayed versus non-delayed surgery.MethodsThis was an international prospective cohort study of consecutive colorectal cancer patients with a decision for curative surgery (January-April 2020). Surgical delay was defined as an operation taking place more than 4 weeks after treatment decision, in a patient who did not receive neoadjuvant therapy. A subgroup analysis explored the effects of delay in elective patients only. The impact of longer delays was explored in a sensitivity analysis. The primary outcome was complete resection, defined as curative resection with an R0 margin.ResultsOverall, 5453 patients from 304 hospitals in 47 countries were included, of whom 6.6% (358/5453) did not receive their planned operation. Of the 4304 operated patients without neoadjuvant therapy, 40.5% (1744/4304) were delayed beyond 4 weeks. Delayed patients were more likely to be older, men, more comorbid, have higher body mass index and have rectal cancer and early stage disease. Delayed patients had higher unadjusted rates of complete resection (93.7% vs. 91.9%, P = 0.032) and lower rates of emergency surgery (4.5% vs. 22.5%, P ConclusionOne in 15 colorectal cancer patients did not receive their planned operation during the first wave of COVID-19. Surgical delay did not appear to compromise resectability, raising the hypothesis that any reduction in long-term survival attributable to delays is likely to be due to micro-metastatic disease

Clinical manifestations of intermediate allele carriers in Huntington disease

Objective: There is controversy about the clinical consequences of intermediate alleles (IAs) in Huntington disease (HD). The main objective of this study was to establish the clinical manifestations of IA carriers for a prospective, international, European HD registry. Methods: We assessed a cohort of participants at risk with <36 CAG repeats of the huntingtin (HTT) gene. Outcome measures were the Unified Huntington's Disease Rating Scale (UHDRS) motor, cognitive, and behavior domains, Total Functional Capacity (TFC), and quality of life (Short Form-36 [SF-36]). This cohort was subdivided into IA carriers (27-35 CAG) and controls (<27 CAG) and younger vs older participants. IA carriers and controls were compared for sociodemographic, environmental, and outcome measures. We used regression analysis to estimate the association of age and CAG repeats on the UHDRS scores. Results: Of 12,190 participants, 657 (5.38%) with <36 CAG repeats were identified: 76 IA carriers (11.56%) and 581 controls (88.44%). After correcting for multiple comparisons, at baseline, we found no significant differences between IA carriers and controls for total UHDRS motor, SF-36, behavioral, cognitive, or TFC scores. However, older participants with IAs had higher chorea scores compared to controls (p 0.001). Linear regression analysis showed that aging was the most contributing factor to increased UHDRS motor scores (p 0.002). On the other hand, 1-year follow-up data analysis showed IA carriers had greater cognitive decline compared to controls (p 0.002). Conclusions: Although aging worsened the UHDRS scores independently of the genetic status, IAs might confer a late-onset abnormal motor and cognitive phenotype. These results might have important implications for genetic counseling. ClinicalTrials.gov identifier: NCT01590589