Coherent structures and bubble-particle velocity in 2-D fluidized beds

This work presents an experimental study to characterize ascending bubbles and granular velocity in the dense phase of a 2-D fluidized bed. Three different non-intrusive techniques based on images obtained with a high speed camera are developed, and applied to the images. First the bubble paths are characterized with time-average concentration maps and the bubble velocities are obtained, using a tracking algorithm over the mass centers of the bubbles. Finally, a PIV (particle image velocimetry) method is used to characterize the particle velocity vectors. This procedure is repeated for different bed aspect ratios, and different superficial gas velocities. This study analyzes the superficial gas velocity influence on the bed behavior, and how the bubble path configuration depends on the bed aspect ratio. The PIV measurements give us information on the location of the recirculation regions and the influence of the superficial gas velocity.Publicad

Circulation of an object immersed in a bubbling fluidized bed

The motion of a large object in a bubbling fluidized bed was experimentally studied using digital image analysis (DIA). The experiments were performed in a 2 D bubbling fluidized bed with glass spheres as bed material. The object motion was measured using non intrusive tracking techniques, while independent measurements of the dense phase velocity (using Particle Image Velocimetry (PIV)) and bubble velocity (using DIA) were carried out. The effect of the dimensionless gas velocity on the object motion was also analyzed. This work characterizes the circulation patterns of an object with a density similar to that of the bed, but much larger in size. Object size and density remained constant throughout the experiments. A comparison between the motion of sinking objects and the motion of the dense phase provided evidence of the feeble effect of buoyant forces on the motion of sinking objects. In contrast, the motion of rising objects is linked to the motion of bubbles. It was found that objects may be raised to the surface of the bed either by the action of a single bubble (one jump) or by several passing bubbles (multiple jumps). Based on these results, the circulation time of objects throughout the bed is a function of two parameters: the maximumdepth attained by an object and the number of jumps during its rising path. This relationship is presented along and the multiple jumps phenomenon is studied in detail. Finally, an estimate of the circulation time of an object based on semi empirical expressions is presented for different dimensionless gas velocities. The probability density function of the circulation time shows two different modes as the object was less prone to be raised atmoderate depths. The estimate of the circulation time was found to be in good agreement with our experimental dataThis work has been partially supported by the National Energy Program of the Spanish Department of Science and Education (ENE2006-01401) and the Madrid Community (CCG07-uc3m/amb-3412 andCCG08-uc3m/amb-4227)Publicad

Exergy Optimization of a Moving Bed Heat Exchanger

The MBHE proposed can be analyzed as a crossflow heat exchanger where one of the phases is a moving granular medium. In the present work the exergy analysis of the MBHE is carried out over operation data of the exchanger obtained in two ways: a numerical simulation of the stationary problem and a simplified analysis. The numerical simulation is carried over the two steady state energy equations (fluid and solid), involving (for the fluid) the convection heat transfer to the solid and the diffusion term in the flow direction, and (for the solid) only the convection heat transfer to the fluid. The simplified analysis followed the well-known e-NTU method, taking the equipment as a crossflow heat exchanger with both fluids unmixed.Publicad

Bioenergy production in Central America: integration of sweet sorghum into sugar mills

This paper aims to evaluate the potential for electricity and ethanol production in Central America using sweet sorghum as an energy crop. Three scenarios were built to analyse sweet sorghum production in terms of the land where it can be cultivated: cropland, sugarcane land in fallow and land in continuous production (intercropping system). The land under permanent crops was not considered for this evaluation. We propose the integration of sweet sorghum into Central American sugar mills, by using the existing machinery to process it. The short growing period of sweet sorghum would allow the Combined Heat and Power (CHP) plants and distilleries to operate outside the sugarcane crushing season using sorghum bagasse and molasses as raw materials. This production could be performed 1 month before, and 1 month after the sugarcane season. Results indicate that by growing sweet sorghum on 5% of Central America's cropland, sorghum could supply around 10% of region's electricity demand. Thus, Central America could increase its CHP share of electricity supply from 4.4% to 5.6%. The increase in renewable electricity production would allow countries such as Guatemala, Honduras and Nicaragua to reduce fossil fuel bills by USD$13, 10 and 20 million, respectively. The ethanol produced from sweet sorghum during off-season can help to implement and maintain a sustainable ethanol program in the region that does not only depend on sugarcane. Sweet sorghum would allow distilleries to easily supply the ethanol required to implement an E5 or ED3 program. Central America could produce about 387 million liters of ethanol by growing sweet sorghum on 5$ 517 million by using ethanol gasoline blends or USD$ 463 million by using ethanol diesel blends.This work was partially founded by the Spanish Agency for International Development Cooperation (AECID) in the development of this research project.Publicad

Tacrolimus prevents TWEAK-induced PLA2R expression in cultured human podocytes

Primary membranous nephropathy is usually caused by antibodies against the podocyte antigen membrane M-type phospholipase A2 receptor (PLA2R). The treatment of membranous nephropathy is not fully satisfactory. The calcineurin inhibitor tacrolimus is used to treat membranous nephropathy, but recurrence upon drug withdrawal is common. TNF superfamily members are key mediators of kidney injury. We have now identified key TNF receptor superfamily members in podocytes and explored the regulation of PLA2R expression and the impact of tacrolimus. Data mining of single cell transcriptomics and glomerular transcriptomics data identified TNFRSF12a/Fn14 as the highest expressed TNF receptor superfamily gene in human membranous nephropathy, and this was confirmed by immunohistochemistry that also identified NFκB activation in membranous nephropathy podocytes. Additionally, glomerular transcriptomics identified PLA2R1 expression as being increased in membranous nephropathy in the parenteral administration of the Fn14 ligand TWEAK increased podocyte PLA2R expression in mice. Furthermore, in cultured human podocytes, TWEAK increased the expression of PLA2R as well as the expression of other genes recently identified by GWAS as linked to membranous nephropathy: NFKB1 and IRF4. Interestingly, IRF4 encodes the FK506-binding protein 52 (FKBP52), a protein associated with tacrolimus. Tacrolimus prevented the increased expression of PLA2R, NFKB1 and IRF4 induced by TWEAK in cultured podocytes. In conclusion, TWEAK upregulates the expression of PLA2R and of other genes linked to membranous nephropathy in podocytes, and this is prevented by tacrolimus. An impact of tacrolimus on the expression of PLA2R and other genes in podocytes may underlie its efficacy in treating the disease as well as the frequent recurrence of nephrotic syndrome upon tacrolimus withdrawalThis research was funded by Instituto de Salud Carlos III FIS PI15/00298, PI16/02057, PI18/01366, PI19/00588, PI19/00815, DTS18/00032, ERA-PerMed-JTC2018 (KIDNEY ATTACK AC18/00064 and PERSTIGAN AC18/00071), ISCIII-RETIC REDinREN RD016/0009 Fondos FEDER, Sociedad Española de Nefrología, EUTOX, Comunidad de Madrid B2017/BMD-3686 CIFRA2-CM, Fundacion Renal Iñigo Alvarez de Toledo (FRIAT) and Grant Fondecyt (Conicyt Chile) 1160465

Increasing Photostability of Inverted Nonfullerene Organic Solar Cells by using Fullerene Derivative Additives

Organic solar cells (OSCs) recently achieved efficiencies of over 18% and are well on their way to practical applications, but still considerable stability issues need to be overcome. One major problem emerges from the electron transport material zinc oxide (ZnO), which is mainly used in the inverted device architecture and decomposes many high-performance nonfullerene acceptors due to its photocatalytic activity. In this work, we add three different fullerene derivatives—PC71BM, ICMA, and BisPCBM—to an inverted binary PBDB-TF:IT-4F system in order to suppress the photocatalytic degradation of IT-4F on ZnO via the radical scavenging abilities of the fullerenes. We demonstrate that the addition of 5% fullerene not only increases the performance of the binary PBDB-TF:IT-4F system but also significantly improves the device lifetime under UV illumination in an inert atmosphere. While the binary devices lose 20% of their initial efficiency after only 3 h, this time is increased fivefold for the most promising ternary devices with ICMA. We attribute this improvement to a reduced photocatalytic decomposition of IT-4F in the ternary system, which results in a decreased recombination. We propose that the added fullerenes protect the IT-4F by acting as a sacrificial reagent, thereby suppressing the trap state formation. Furthermore, we show that the protective effect of the most promising fullerene ICMA is transferable to two other binary systems PBDB-TF:BTP-4F and PTB7-Th:IT-4F. Importantly, this effect can also increase the air stability of PBDB-TF:IT-4F. This work demonstrates that the addition of fullerene derivatives is a transferable and straightforward strategy to improve the stability of OSCs

Leptospirosis Prevalence in Patients with Initial Diagnosis of Dengue

Objective. To determine the prevalence of leptospirosis in patients from Veracruz with initial diagnosis of dengue and its association with risk factors. Materials and Methods. Transversal study in patients who sought medical attention under the suspicion of dengue. Backgrounds were researched and blood samples were drawn to determine dengue (NS1, RT-PCR) and leptospirosis (IFI). Simple frequencies, central tendency and dispersion measures, and prevalence and trust intervals at 95% (IC95%) were obtained. Prevalence reasons (RP) and IC95% were obtained and a multivariate logistic model was applied, using SPSS V15. Results. 171 patients were included, 56% women (32 ± 14 years) and 44% men (32 ± 17 years). 48% of the cases (IC95% 40.5–55.4) was positive to dengue, with a cut point of 1 : 80, seroprevalence for leptospirosis was of 6% (IC95% 2.7–10); 12% (IC95% 7–16.5) was positive to both pathologies and 34% was negative to both tests. Although the largest number of isolations corresponded to serotype 2, the four dengue virus serotypes were identified. In the bivariate analysis, overcrowding RP = 1.33, (IC = 0.46–3.5), bathing in rivers (RP = 1.31, IC = 0.13–7.4), and walking barefoot (RP = 1.39, IC = 0.58–3.3) were the variables associated with leptospirosis, although the relation was not statistically significant. Conclusions. Leptospirosis prevalence in subjects under suspicion of dengue fever is high, as well as the coincidence of both infections. The results show the coexistence of overlapped outbreaks of several diseases sharing the side of transmission. It is necessary the intentional search of other pathologies, such as influenza, rickettsiosis, and brucella, among others

Extracción del aroma de la trufa negra (Tuber melanosporum) mediante CO2 supercrítico

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Afectaciones en la producción de cerdos en una granja comercial en el noreste de México

ESPAÑOL: Al evaluar la productividad de cerdas de una granja comercial en el noreste de México para el número de parto, solamente se presentó un efecto (P< 0.05) sobre el intervalo destetecelo. Se presentó un efecto significativo (P <0.05) de la línea materna sobre el intervalo destete-celo y el intervalo entre partos. El grupo de año influyó sobre el intervalo destetecelo, y se obtuvieron los valores más bajos en los grupos 1992 -1994, 1995-1997 y 2004-2006. En cuanto a la época de servicio, no se encontraron efectos significativos para las variables estudiadas. Con relación a los factores ambientales es importante considerarlos desde el punto de vista reproductivo en este tipo de granja comercial. ENGLISH: In assessing the productivity of sows from a commercial farm in northeastern Mexico for parity number, only the effect on the interval from weaning to estrus was significant (P <0.05). There was a significant effect (P <0.05) in the maternal line on weaning-estrus interval and calving interval. Year group influenced the weaning-estrus interval, obtaining the lowest values in the groups 1992 -1994, 1995-1997, and 2004-2006. As for the time of service, no significant effects were found for the variables studied. With regard to environmental factors it is important to consider them from the point of view in this kind of commercial farms

The neglected influence of zinc oxide light‐soaking on stability measurements of inverted organic solar cells

Although zinc oxide (ZnO) is one of the most commonly used materials for electron transport layers in organic solar cells (OSCs), it also comes with disadvantages such as the so‐called light‐soaking issues, i.e., its need for exposure to UV light to reach its full potential in OSCs. Here, the impact of ZnO light‐soaking issues on stability measurements of OSCs is investigated. It is found that in the absence of UV light a reversible degradation occurs, which is independent of the used active layer material and accelerates at higher temperatures but can be undone with a short UV exposure. This reversible aging is attributed to the re‐adsorption of oxygen, which for manufacturing reasons is trapped at the interface of ZnO, even in an oxygen‐free environment. This oxygen can be removed with a UV pretreatment of the ZnO but at the expense of device efficiency and production that has to take place in an oxygen‐free environment. This study establishes that stability measurements of ZnO‐containing OSCs must be performed exclusively with a light source including a UV part since the usage of a simple white light source – as often reported in the literature – can lead to erroneous results