Production of a biodiesel-like biofuel without glycerol generation, by using Novozym 435, an immobilized Candida antarctica lipase

Background: Novozym 435, a commercial lipase from Candida antarctica, recombinant, expressed in Aspergillus niger, immobilized on macroporous acrylic resin, has been already described in the obtention of biodiesel. It is here evaluated in the production of a new biofuel that integrates the glycerol as monoglyceride (MG) together with two fatty acid ethyl esters (FAEE) molecules by the application of 1,3-selective lipases in the ethanolysis reaction of sunflower oil. Results: Response surface methodology (RSM) is employed to estimate the effects of main reaction. Optimum conditions for the viscosity, selectivity, and conversion were determined using a multifactorial design of experiments with three factors run by the software Stat Graphics version XV.I. The selected experimental parameters were reaction temperature, oil/ethanol ratio and alkaline environment. On the basis of RSM analysis, the optimum conditions for synthesis were 1/6 oil/EtOH molar ratio, 30°C, and 12.5 μl of NaOH 10 N aqueous solutions, higher stirring than 300 rpm, for 2 h and 0.5 g of biocatalyst. Conclusions: These obtained results have proven a very good efficiency of the biocatalyst in the studied selective process. Furthermore, it was allowed sixteen times the successive reuse of the biocatalyst with good performanc

Biocatalytic behaviour of immobilized Rhizopus oryzae lipase in the 1,3-selective ethanolysis of sunflower oil to obtain a biofuel similar to biodiesel

A new biofuel similar to biodiesel was obtained in the 1,3-selective transesterification reaction of sunflower oil with ethanol using as biocatalyst a Rhizopus oryzae lipase (ROL) immobilized on Sepiolite, an inorganic support. The studied lipase was a low cost powdered enzyme preparation, Biolipase-R, from Biocon-Spain, a multipurpose additive used in food industry. In this respect, it is developed a study to optimize the immobilization procedure of these lipases on Sepiolite. Covalent immobilization was achieved by the development of an inorganic-organic hybrid linker formed by a functionalized hydrocarbon chain with a pendant benzaldehyde, bonded to the AlPO4 support surface. Thus, the covalent immobilization of lipases on amorphous AlPO 4/sepiolite (20/80 wt %) support was evaluated by using two different linkers (p-hydroxybenzaldehyde and benzylamine-terephthalic aldehyde, respectively). Besides, the catalytic behavior of lipases after physical adsorption on the demineralized sepiolite was also evaluated. Obtained results indicated that covalent immobilization with the p-hydroxybenzaldehyde linker gave the best biocatalytic behavior. Thus, this covalently immobilized lipase showed a remarkable stability as well as an excellent capacity of reutilization (more than five successive reuses) without a significant loss of its initial catalytic activity. This could allow a more efficient fabrication of biodiesel minimizing the glycerol waste production. © 2014 by the authors.Grants from the Spanish Ministry of Economy and Competitiveness (Project ENE 2011-27017), Spanish Ministry of Education and Science (Projects CTQ2010-18126 and CTQ2011-28954-C02-02), FEDER funds and Junta de Andalucía FQM 0191, PO8-RMN-03515 and P11-TEP-7723 are gratefully acknowledged by the authors. We are also gratefully to Biocon®-Spain, for the kindly supply of the BIOLIPASE-R®. We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI)Peer Reviewe

Preparation of Cu(In,Ga)Se2 photovoltaic absorbers by an aqueous metal selenite co-precipitation route

In this paper, we report a novel and simple solution-based approach for the fabrication of chalcopyrite Cu(In,Ga)Se2 thin film solar cells. An aqueous co-precipitation method based on metal selenites, M2(SeO3)x (M = Cu, In, Ga) precursors was investigated. The resulting powder, dispersed in a binder to form an ink, was coated on a substrate by doctor blade technique. A soft annealing treatment allowed the reduction of metal selenites into selenides. Further rapid thermal processing (RTP) achieved crystalline chalcopyrite absorber. The obtained layer provides good compositional control and adequate morphology for solar cell applications. The water-based synthesis is a sustainable and simple procedure, and together with doctor blade printing, provides a potential cost-effective advantage over conventional fabrication processes (vacuum-based deposition techniques). The short circuit current (JSC), open circuit voltage (VOC), fill factor (FF), and total area power conversion efficiency (Eff.) of the device are 26 mA/cm2, 450 mV, 62%, and 7.2%, respectively. The effective band gap of 1.12 eV confirmed Ga-incorporation in the CIGS crystal lattice.This work was supported by the Spanish Ministry of Science and Competiveness under INNPACTO Program (IPT-2011-0913- 920000). The authors would like to thanks to Manuel Ocana Jurado ~ (ICMS-CISC) for his help in the XPS measurements. L. Oliveira would like to thank the support of the National Council for Scientific and Technological Development (CNPq) e Brazil

Estudio líquido

De partida, debemos aproximarnos a la pintura de Paco Lara-Barranco (Torredonjimeno, Jaén, 1964) asumiendo que es resultado de una investigación constante, de un conti-nuum. Los cuadros que surgen de ese recorrido se generan en territorios nuevos que el artista va pisando con expectación y pausa. En su trabajo, actúa como un explorador que se adentra en una comarca virgen donde tiene que desbrozar y estar atento al mis-mo tiempo, desechando algunas pistas y asiendo otras. Este viaje hacia lo desconocido va revelando etapas a partir de elementos distintos cada vez. Sin dejar de moverse por una misma geografía pictórica, la suya propia que inicia a principios del año 2004 (Figura 1), encuentra paisajes y orografías diferentes según las circunstancias que van marcando el camino avanzado. A veces cobra importancia la materia sobre la superficie como ocurría en series anteriores (Cuando la pintura se vuelve caramelo, 2006, Acerca de lo oculto, 2009); en otras, como en este nuevo periodo en el que lleva inmerso desde hace tres años, resulta esencial la relación entre fondo y primer término. Los enlaces entre ambos periodos son lentos y meditados. Incluso ya se incluyen en esta muestra rasgos distintivos de su siguiente tramo, donde las texturas de un charco toman prota-gonismo y determinarán la condición táctil de la obra

Vacuum effects in an asymptotically uniformly accelerated frame with a constant magnetic field

In the present article we solve the Dirac-Pauli and Klein Gordon equations in an asymptotically uniformly accelerated frame when a constant magnetic field is present. We compute, via the Bogoliubov coefficients, the density of scalar and spin 1/2 particles created. We discuss the role played by the magnetic field and the thermal character of the spectrum.Comment: 17 pages. RevTe

Critical role of AMP-activated protein kinase in the balance between mitophagy and mitochondrial biogenesis in MELAS disease

MELAS syndrome is a mitochondrial disorder that is caused mainly by the m.3243A > G mutation in mitochondrial DNA. Here, we report on how the severity of pathophysiological alterations is differently expressed in fibroblasts derived from patients with MELAS disease. We evaluated mitophagy activation and mitochondrial biogenesis which are the main mechanisms regulating the degradation and genesis of mitochondrial mass in MELAS fibroblasts and transmitochondrial cybrids. Our results suggest a critical balance between mitophagy and mitochondrial biogenesis which leads to the expression of different degrees of pathological severity among MELAS fibroblast cell lines according to their heteroplasmy load and the activation of AMP-activated protein kinase (AMPK). AMPK-activators such as 5-aminoimidazole-4-carboxamide 1-β-D-ribofuranoside (AICAR) or coenzyme Q10 (CoQ) increased peroxisome proliferator-activated receptor alpha (PGC-1α) nuclear translocation, mitochondrial biogenesis, antioxidant enzyme system response, autophagic flux and improved pathophysiological alterations in MELAS fibroblasts with the most severe phenotype. Our findings support the hypothesis that mitochondrial biogenesis, increased antioxidant response and autophagy clearance serve as compensatory mechanisms in response to mitophagic degradation of dysfunctional mitochondria and point out that AMPK is an important player in this balance.This work was supported by FIS PI13/00129 grant, Ministerio de Sanidad, Spain and Fondo Europeo de Desarrollo Regional (FEDER-Unión Europea), Proyecto de Investigación de Excelencia de la Junta de AndalucíaCTS-5725, and by AEPMI (Asociación de Enfermos de Patología Mitocondrial).Peer Reviewe

Resistive Switching and Charge Transport in Laser-Fabricated Graphene Oxide Memristors: A Time Series and Quantum Point Contact Modeling Approach

This work investigates the sources of resistive switching (RS) in recently reported laser-fabricated graphene oxide memristors by means of two numerical analysis tools linked to the Time Series Statistical Analysis and the use of the Quantum Point Contact Conduction model. The application of both numerical procedures points to the existence of a filament connecting the electrodes that may be interrupted at a precise point within the conductive path, resulting in resistive switching phenomena. These results support the existing model attributing the memristance of laser-fabricated graphene oxide memristors to the modification of a conductive path stoichiometry inside the graphene oxide.The authors thank the support of the Spanish Ministry of Science, Innovation and Universities under projects TEC2017-89955-P, TEC2017-84321-C4-3-R, MTM2017-88708-P and project PGC2018-098860-B-I00 (MCIU/AEI/FEDER, UE), and the predoctoral grant FPU16/01451

Structural signatures of igneous sheet intrusion propagation

The geometry and distribution of planar igneous bodies (i.e. sheet intrusions), such as dykes, sills, and inclined sheets, has long been used to determine emplacement mechanics, define melt source locations, and reconstruct palaeostress conditions to shed light on various tectonic and magmatic processes. Since the 1970’s we have recognised that sheet intrusions do not necessarily display a continuous, planar geometry, but commonly consist of segments. The morphology of these segments and their connectors is controlled by, and provide insights into, the behaviour of the host rock during emplacement. For example, tensile brittle fracturing leads to the formation of intrusive steps or bridge structures between adjacent segments. In contrast, brittle shear faulting, cataclastic and ductile flow processes, as well as heat-induced viscous flow or fluidization, promotes magma finger development. Textural indicators of magma flow (e.g., rock fabrics) reveal that segments are aligned parallel to the initial sheet propagation direction. Recognising and mapping segment long axes thus allows melt source location hypotheses, derived from sheet distribution and orientation, to be robustly tested. Despite the information that can be obtained from these structural signatures of sheet intrusion propagation, they are largely overlooked by the structural and volcanological communities. To highlight their utility, we briefly review the formation of sheet intrusion segments, discuss how they inform interpretations of magma emplacement, and outline future research directions.Facultad de Ciencias Naturales y Muse

Secondary coenzyme Q10 deficiency triggers mitochondria degradation by mitophagy in MELAS fibroblasts

9 páginas.Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) is a mitochondrial disease most usually caused by point mutations in tRNA genes encoded by mtDNA. Here, we report on how this mutation affects mitochondrial function in primary fibroblast cultures established from 2 patients with MELAS who harbored the A3243G mutation. Both mitochondrial respiratory chain enzyme activities and coenzyme Q(10) (CoQ) levels were significantly decreased in MELAS fibroblasts. A similar decrease in mitochondrial membrane potential was found in intact MELAS fibroblasts. Mitochondrial dysfunction was associated with increased oxidative stress and the activation of mitochondrial permeability transition (MPT), which triggered the degradation of impaired mitochondria. Furthermore, we found defective autophagosome elimination in MELAS fibroblasts. Electron and fluorescence microscopy studies confirmed a massive degradation of mitochondria and accumulation of autophagosomes, suggesting mitophagy activation and deficient autophagic flux. Transmitochondrial cybrids harboring the A3243G mutation also showed CoQ deficiency and increased autophagy activity. All these abnormalities were partially restored by CoQ supplementation. Autophagy in MELAS fibroblasts was also abolished by treatment with antioxidants or cyclosporine, suggesting that both reactive oxygen species and MPT participate in this process. Furthermore, prevention of autophagy in MELAS fibroblasts resulted in apoptotic cell death, suggesting a protective role of autophagy in MELAS fibroblasts.This work was supported by Ministerio de Sanidad, Spain, grants FIS PI080500 and FIS EC08/00076, and by Asociación de Enfermos de Patología Mitocondrial (AEPMI) and Fundación Española de Enfermedades Lisosomales (FEEL). M. de la Mata is the recipient of a fellowship from Colegio Oficial de Farmacéuticos de Sevilla. This group was founded by the Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III (ISCIII).Peer reviewe