Elucidating the role of pH and total solids content in the co-production of biohydrogen and carboxylic acids from food waste via lactate-driven dark fermentation

Producción CientíficaNotwithstanding lactate-driven dark fermentation (LD-DF) can cope with inhibition issues associated with the over-proliferation of lactate producers, there is still a knowledge gap about the role of key operational parameters. In this study, the effect of pH and total solids (TS) content on the co-production of hydrogen and carboxylic acids, including medium-chain carboxylic acids (MCCAs), from food waste (FW) via LD-DF was investigated. A series of batch fermentations was conducted, first, without pH control, and then at fixed pH values of 5.5, 6.0 and 6.5, while maintaining constant the TS content at 5 %. It was observed that the higher the operational pH, the lower the accumulation of lactate and the higher the extent and rate of hydrogen production, sustaining a maximum hydrogen production yield and rate of 81 NmL/g VS fed and 9 NL/L-d, respectively, at pH 6.5. In a second series of batch tests, the TS content was adjusted to 5, 7.5 and 10 % while pH was set at 6.5. The highest hydrogen production performance (103 NmL/g-VS fed and 13.3 NL/L-d) was achieved at 7.5 % TS, which also resulted in the highest accumulation of MCCAs, particularly of caproate, with an associated titer of 8.7 g/L. Hydrogen production plateaued with the exhaustion of lactate regardless of the condition tested. Further assessment through biochemical methane potential tests showed that LD-DF effluents can be alternatively valorised into biogas. Overall, the results obtained confirmed the key role of pH and TS content in the LD-DF of FW and suggested that this non-conventional route may be an alternative approach to cope with lactate flux diverted toward undesirable non-hydrogen-producing metabolic pathways.European Commission-H2020-MSCA-IF-2019 project UP-GRAD (894515)Junta de Castilla y León y EU-FEDER (program CLU 2017-09, CL-EI-2021-07, and UIC 315

Continuous lactate-driven dark fermentation of restaurant food waste: Process characterization and new insights on transient feast/famine perturbations

Producción CientíficaThe effect of hydraulic retention time (HRT) on the continuous lactate-driven dark fermentation (LD-DF) of food waste (FW) was investigated. The robustness of the bioprocess against feast/famine perturbations was also explored. The stepwise HRT decrease from 24 to 16 and 12 h in a continuously stirred tank fermenter fed with simulated restaurant FW impacted on hydrogen production rate (HPR). The optimal HRT of 16 h supported a HPR of 4.2 L H2/L-d. Feast/famine perturbations caused by 12-h feeding interruptions led to a remarkable peak in HPR up to 19.2 L H2/L-d, albeit the process became stable at 4.3 L H2/L-d following perturbation. The occurrence of LD-DF throughout the operation was endorsed by metabolites analysis. Particularly, hydrogen production positively correlated with lactate consumption and butyrate production. Overall, the FW LD-DF process was highly sensitive but resilient against transient feast/famine perturbations, supporting high-rate HPRs under optimal HRTs.European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 894515MCIN/AEI /10.13039/501100011033 - Unión Europea NextGenerationEU/PRTR (Grant RYC2021‐034559‐I)Junta de Castilla y León - EU-FEDER (CLU 2017-09, CL-EI-2021-07 y UIC 315

Three newly described species of carex sect. fecundae (cyperaceae) from Central America and typification of two related names

Three new species of Carex sect. Fecundae (Cyperaceae) are described from Central America. Carex orothanatica from Costa Rica, Carex siguanabae occurring in El Salvador and Honduras, and Carex via-aquae from Costa Rica and Panama. The three new species are compared with relatives. In addition, two related names, Carex lehmanniana Boott, and C. lehmaniana var. simplex Kük., are lectotypifie

Momento Económico (10-11)

En este Temas de hoy, 2/ La economía cubana en 1984, 3/ Alicia Girón: La renegociación de la deuda externa, 13/ Mario J. Zepeda: 1984: Primer semestre, 17/ Raúl Huerta García: Repunte de la industria nacional en 1984, 23/ Manuel Lois Méndez: Crisis y número : cambios recientes en la industria automotriz, 2

Biotic and abiotic insights into the storage of food waste and its effect on biohydrogen and methane production potential

Producción CientíficaThe present study investigated the physicochemical and microbiological changes occurring during the storage of simulated restaurant food waste (FW) and how such changes affected its biohydrogen and biogas production potential. FW was stored for 72 h in a closed atmosphere under two different scenarios: i) without and ii) with inoculation of a mixed microbial culture harboring lactic acid bacteria (LAB). Both storage scenarios resulted in similar biotic and abiotic changes in FW. Particularly, FW was pre-acidified and pre-hydrolyzed to some extent during the storage, resulting in a feedstock enriched in LAB (≈ 95 % total relative abundance) and lactate (10.5–12.3 g/L, 87.0–90.5 % selectivity). Biochemical hydrogen potential tests revealed that the use of stored FW resulted in similar or even higher hydrogen production efficiencies compared to that of non-stored FW, achieving up to 60 NmL H2/g VS added and a maximum volumetric hydrogen production rate of 9.7 NL H2/L-d. Metabolically, the conversion of lactate into hydrogen was crucial regardless of the use of non-stored or stored FW, albeit the presence of fermentable carbohydrates in the substrate was also essential either to produce lactate or to co-produce extra hydrogen. On the contrary, biochemical methane potential tests showed that the biogas production potential of FW was not affected by storage, yielding on average 400 NmL CH4/g VS added and revealing that lactate oxidation to methane precursors represented an important step in FW biomethanization.European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 894515Ministerio de Ciencia e Innovación - AEI and European Union NextGenerationEU/PRTR (RYC2021-034559-I)Junta de Castilla y León and the European FEDER Programme (CLU 2017-09, CL-EI-2021-07 y UIC 315

Mixtures of Ethylammonium Nitrate and Ethylene Carbonate: Bulk and Interfacial Analysis

[Abstract] The structure and dynamics of binary mixtures of a protic ionic liquid (ethylammonium nitrate) and ethylene carbonate are studied by means of atomistic molecular dynamics simulations and experimental measurements both in bulk and at the electrochemical interface. The solubility limit was experimentally found at 0.6 carbonate molar fraction. Likewise, density and conductivity experimental data are compared with computational results. Also, distribution and correlation functions obtained from bulk simulations are analyzed in the miscible range to clarify the role of the carbonate in the coordination and diffusion of ionic species. Understanding the evolution of the hydrogen bond network is of particular importance since its strength is detected as the most relevant feature in the structural organization of the mixture. Regarding the effects of the presence of an interface, the orientations of the molecules and the density and charge profiles are calculated both in the absence and in the presence of an electric field. This analysis reveals the tendency of the carbonate to displace the ionic liquid from the near-wall region when concentration is increased.The financial support of the Spanish Ministry of Science and Innovation (PID2021-126148NA-I00 funded by MCIN/AEI/10.13039/501100011033/FEDER, UE) is gratefully acknowledged. Moreover, this work was funded by the Xunta de Galicia (ED431E 2018/08 and GRC ED431C 2020/10). All these research projects were partially supported by FEDER. Authors acknowledge P. Rojo-Garea (iMATUS, University of Santiago de Compostela) for the technical support in conductivity experimental measurements. A.R.P. thanks the Spanish Ministry of Education for his FPU grant. M.O.L. wishes to thank the Xunta the Galicia for his “Axudas de apoio á etapa predoutoral” grant. T. M. M. acknowledges her contract funded by the pilot program of the USC for the recruitment of distinguished research personnel—call 2021 under the agreement between the USC and the Santander Bank for 2021–2024. H.M.C. thanks the USC for his “Convocatoria de Recualificación do Sistema Universitario Español-Margarita Salas” postdoctoral grant under the “Plan de Recuperación Transformación” program funded by the Spanish Ministry of Universities with European Union's NextGenerationEU funds. P.V. thanks the Spanish Ministry of Education for his FPI grant. J.J.P. thanks I2C postdoctoral Program of Xunta de Galicia. R.L.C. acknowledges his Predoctoral Contract under the framework of the project PID2021-126148NA-I00 funded by MCIN/AEI/10.13039/501100011033/FEDER, UE. Facilities provided by the Galician Supercomputing Centre (CESGA) are also acknowledgedXunta de Galicia; ED431E 2018/08Xunta de Galicia; GRC ED431C 2020/1

Anillos vasculares y compresión traqueo-esofágica: 15 años de experiencia quirúrgica

ResumenIntroducción y objetivosLos anillos vasculares son anomalías poco comunes, en los que el enfoque diagnóstico y quirúrgico puede ser controvertido. El objetivo es revisar nuestros resultados quirúrgicos hospitalarios y en seguimiento.MétodosEstudio observacional descriptivo de pacientes con anillos vasculares intervenidos en nuestro hospital.ResultadosSe incluyó a 26 pacientes con una mediana de edad de 9 meses (rango: 1 mes-38 años). Los pacientes fueron clasificados en 3 grupos: arco aórtico derecho-ligamento ductal izquierdo (n=14), doble arco aórtico (n=9) y sling pulmonar (n=3). Un total de 3 casos fueron diagnosticados en el periodo prenatal (11,5%). En todos los casos el diagnóstico se realizó mediante tomografía computarizada (TC). Se observó divertículo de Kommerell en 11 pacientes (42,3%). Un 19,2% presentaron anomalías intracardiacas asociadas que requirieron cirugía.El abordaje quirúrgico principal fue la toracotomía izquierda con un 72,7%. Un 9,1% requirió cirugía traqueal. Un 13,6% preciso reintervención del anillo vascular.La necesidad de reintervención se asoció estadísticamente a ventilación mecánica previa, traqueomalacia y persistencia de síntomas respiratorios. No hubo mortalidad hospitalaria. La mortalidad en seguimiento ha sido 7,6%, debido a malformaciones mayores asociadas.ConclusionesEl principal método diagnóstico en nuestra serie es la TC.La broncoscopia antes y después del tratamiento quirúrgico permite evaluar el resultado de la técnica; en algunos casos ayuda a valorar la necesidad de realizar una pexia aórtica.La presencia de traqueomalacia y defectos estructurales en la vía aérea, junto con la asociación de cardiopatías congénitas severas, marcan el pronóstico en el seguimiento.AbstractIntroduction and objectivesVascular rings are rare anomalies where the diagnosis and surgical approach can be controversial. The goal of this article is to review our hospital surgical results and follow-up.MethodsDescriptive observational study of patients with vascular rings operated on in our hospital from the year 2000 to 2015.ResultsThe study included 26 patients with a median age of 9 months (range: 1 month - 38 years). Patients were classified into 3 groups: right aortic arch - left ductal ligament (n=14), double aortic arch (n=9), and pulmonary sling (n=3). Prenatal diagnosis was made in 3 cases (11.5%). In all cases the diagnosis was made by computed tomography (CT). Kommerell's diverticulum was observed in 11 patients (42.3%), and 19.2% showed intracardiac anomalies that required surgery.The main surgical approach was left thoracotomy with 72.7%. Tracheal surgery was required in 9.1% and 13.6% required re-operation of the vascular ring.The need for re-operation was associated with previous mechanical ventilation, tracheomalacia, and the persistence of respiratory symptoms. There was no hospital mortality. The late mortality was 7.6%, due to associated major malformations.ConclusionsThe reference method for the diagnosis of vascular ring is computed tomography.Bronchoscopy before and after surgical treatment allows the outcome of the technique to be assessed and, in some cases, helps to assess the need for aortopexy.Tracheomalacia and the presence of structural defects in the airway, along with the association of severe congenital heart disease, are factors that are associated with late mortality

Desbrozando caminos en el estudio taxonómico de insectos: una experiencia con taxonomía afídica

Estudiar la taxonomía de cualquier grupo animal requiere de conocimientos específicos del grupo taxonómico en cuestión. En este caso, se expone cómo hemos adquirido las competencias suficientes como para empezar a estudiar la taxonomía de los áfidos (Aphididae), iniciándonos con la identificación y el estudio morfométrico de esta familia de Hemípteros y continuando con un estudio más profundo aún en desarrollo

Pelecitus tercostatus (Molin, 1960) (Nematoda, Onchocercidae) in Amazona vinacea (Aves, Psittaciformes) from Argentina: Morphological details and clinical findings

Pelecitus tercostatus (Molin, 1860) (Onchocercidae, Dirofilariinae) was found in the leg of a Vinaceous-breasted Parrot Amazona vinacea (Aves, Psittaciformes) from Misiones, Argentina. The present report enlarges the host distribution of the species and represents the first record of any nematode in A. vinacea. The macroscopic lesions produced in the bird are also described.Centro de Estudios Parasitológicos y de Vectore