Mechanism of the synergistic inactivation of Escherichia coli by UV-C light at mild temperatures

UV light only penetrates liquid food surfaces to a very short depth, thereby limiting its industrial application in food pasteurization. One promising alternative is the combination of UV light with mild heat (UV-H), which has been demonstrated to produce a synergistic bactericidal effect. The aim of this article is to elucidate the mechanism of synergistic cellular inactivation resulting from the simultaneous application of UV light and heat. The lethality of UV-H treatments remained constant below ~45ºC, while lethality increased exponentially as the temperature increased. The percentage of synergism reached a maximum (40.3%) at 55ºC. Neither the flow regimen nor changes in the dose delivered by UV lamps contributed to the observed synergism. UV-H inactivation curves of the parental Escherichia coli strain obtained in a caffeic acid selective recovery medium followed a similar profile to those obtained with uvrA mutant cells in a nonselective medium. Thermal fluidification of membranes and synergistic lethal effects started around 40 to 45ºC. Chemical membrane fluidification with benzyl alcohol decreased the UV resistance of the parental strain but not that of the uvrA mutant. These results suggest that the synergistic lethal effect of UV-H treatments is due to the inhibition of DNA excision repair resulting from the membrane fluidification caused by simultaneous heating

Evaluation of (MnxFe1-x)2TiyOz Particles as Oxygen Carrier for Chemical Looping Combustion

The present work accomplishes a screening of the performance of Mn-Fe-Ti based oxygen carriers, prepared with different Mn/(Mn+Fe) molar ratios in the general formula (MnyFe1-y)Ti0.15Ox. The oxygen carriers were prepared by physical mixing followed by pelletizing under pressure, calcining, crushing and sieving in the 100-300 µm particle size interval. The characterization of the carriers is based on the evaluation of their crushing strength, magnetic properties and reduction and oxidation behavior through TGA experiments at temperatures suitable for the CLC process (i.e. 850-950 °C). In addition, the main chemical structures of the Mn-Fe-Ti system were identified as a function of the Mn/(Mn+Fe) molar ratio. Oxygen uncoupling property was analyzed by reduction under a N2 atmosphere and the capability to interact with fuel gases was analyzed by using CH4, H2 and CO. Results indicate that the (MnyFe1-y)Ti0.15Ox oxygen carriers with Mn/(Mn+Fe) molar ratios of 0.55-0.87 have very promising properties for the CLC process with solid fuels

Promising Impregnated Mn-based Oxygen Carriers for Chemical Looping Combustion of Gaseous Fuels

Promising impregnated oxygen carriers, based on copper and iron, have been previously developed for CLC with gaseous fuels (CH4, syngas, LHC). Recently, because of its low cost and environmental compatibility, Mn-based oxygen carriers are now being considered as an attractive option for chemical-looping combustion (CLC) applications. In this work, a screening of different commercial supports in fluidizable particle size for impregnated Mn-based materials has been carried out. Different oxygen carriers have been prepared by incipient impregnation on ZrO2, and CaAl2O4, and evaluated with respect to their mechanical resistance, fuel gas reactivity and fluidization properties such as agglomeration and attrition rate. In a first step, particles showing high enough crushing strength values were selected for the reactivity investigation. The redox reactivity was evaluated through TGA experiments at suitable temperatures for the CLC process (i.e. 850-950 °C) using H2, CO and CH4. Multi cycle redox analysis and full physical and chemical characterization was also performed. In a second step, materials with high enough reactivity were prepared for fluidized bed evaluation. A batch fluidized bed installation with continuous gaseous fuel feed was used to analyze the product gas distribution during reduction and oxidation reactions at different operation temperatures, and agglomeration and attrition behavior of the selected materials. Results showed that an oxygen carrier impregnated using ZrO2 as support, had high enough reactivity and low attrition rate. Therefore, this material can be selected as a candidate for the development of CLC with syngas with promising results

Scale-up of CLC oxygen carriers for gaseous fuels

Chemical Looping Combustion, CLC, is one of the most promising processes to capture CO2 at a low cost. It is based on the transfer of the oxygen from air to the fuel by using a solid oxygen carrier that circulates in dual fluidized bed systems. The CO2 capture is inherent to this process, as the air does not get mixed with the fuel. However, the CLC process is still under development waiting for a large scale demonstration experience. The key issue in the system performance is the oxygen carrier material. The oxygen carrier must fulfil several characteristics such as high reactivity and good fluidization properties, that will rely on their redox system and the support. Therefore, the identification of raw materials, available at multi-tonn scale at a competitive price, is one of requirements for the success of the technology. Promising impregnated oxygen carriers, based on copper and iron, have been developed to perform well for gaseous fuels (CH4, syngas , LHC..), although they were prepared from not commercially scalable production supports. In this work, the performance of different impregnated materials, prepared with commercial-scale supports, was analyzed during methane combustion in a continuous 500 Wth CLC unit to identify the best material based on reactivity, attrition resistance and sulfur tolerance. A copper-based material with improved performance than the reference material was identified and therefore proposed as the best oxygen carrier for scale-up CLC technology for gaseous fuels

¿Dónde está el tronco coronario izquierdo?

La incidencia de anomalías coronarias es baja en la población general, oscilando entre el 0.46-1.55%, y la agenesia de tronco coronario izquierdo (TCI) es una de las menos observadas1, 2. Se trata de una entidad extremadamente rara en la que no existe el ostium coronario izquierdo y el TCI termina ciegamente3. De los casos publicados, el 50% afectan a la edad pediátrica, y entre ellos, el 30% se asocia a otras anomalías coronarias4. Puede aparecer aisladamente, como en los pacientes que aquí mostramos, o asociada a otras enfermedades, como la homocistinuria, la ataxia de Friedreich, el síndrome de Hurler, la progeria y el síndrome rubeólico5. Se presentan 2 casos clínicos representativos de esta enfermedad de baja prevalencia en la población general. El primer caso se trata de un varón de 59 años con hipercolesterolemia y extabaquismo como factores de riesgo cardiovascular. Es derivado a nuestro centro para la realización de una coronariografía por angina de esfuerzo, con ergometría clínicamente negativa y eléctricamente positiva con descenso del segmento ST de 2mm en el tercer estadio del protocolo de Bruce. El cateterismo muestra una agenesia del TCI con visualización de un vaso hipoplásico submilimétrico. La arteria descendente anterior se visualiza a través de la arteria coronaria anómala, que nace de la rama marginal aguda precoz desde el segmento proximal de la coronaria derecha (CD). El trayecto anómalo presenta efecto kinking y compresión sistólica. La circunfleja se visualiza a través de la arteria conal, con salida independiente en cañón de escopeta ligeramente craneal al ostium de la CD, con trayecto anómalo y efecto kinking sin evidente efecto milking. La CD es dominante, de gran calibre y sin estenosis angiográficamente significativas..

Rapid haplotype inference for nuclear families

Hapi is a new dynamic programming algorithm that ignores uninformative states and state transitions in order to efficiently compute minimum-recombinant and maximum likelihood haplotypes. When applied to a dataset containing 103 families, Hapi performs 3.8 and 320 times faster than state-of-the-art algorithms. Because Hapi infers both minimum-recombinant and maximum likelihood haplotypes and applies to related individuals, the haplotypes it infers are highly accurate over extended genomic distances.National Institutes of Health (U.S.) (NIH grant 5-T90-DK070069)National Institutes of Health (U.S.) (Grant 5-P01-NS055923)National Science Foundation (U.S.) (Graduate Research Fellowship

Mercury release and speciation in chemical looping combustion of coal

In the in situ Gasification Chemical Looping Combustion of coal (iG-CLC), the fuel is gasified in situ in the fuel reactor and gasification products are converted to CO2 and H2O by reaction with the oxygen carrier. This work is the first study on mercury release in Chemical Looping Combustion of coal. The fraction of the mercury in coal vaporized in the fuel reactor depended mainly on the fuel reactor temperature and the coal type. In the fuel reactor, mercury was mainly emitted as Hg0 in the gas phase and the amount increased with the temperature. In the air reactor, mercury was mostly emitted as Hg2+. In a real CLC system, mercury emissions to the atmosphere will decrease compared to conventional combustion as only mercury released in the air reactor will reach the atmosphere. However, measures should be taken to reduce Hg0 in the CO2 stream before the purification and compression steps in order to avoid operational problems.The authors thank the Government of Aragón and La Caixa (2012-GA-LC-076 project) and the Spanish Ministry for Science and Innovation (ENE2010-19550 project) for the financial support. P. Gayán thanks CSIC for the financial support of the project 201180E102. The authors also thank to Alcoa Europe-Alúmina Española S.A. for providing the Fe-enriched sand fraction used in this work. G. Galo is acknowledged for his contribution to the experimental results.Peer reviewe

A General Model for Multilocus Epistatic Interactions in Case-Control Studies

Background: Epistasis, i.e., the interaction of alleles at different loci, is thought to play a central role in the formation and progression of complex diseases. The complexity of disease expression should arise from a complex network of epistatic interactions involving multiple genes. Methodology: We develop a general model for testing high-order epistatic interactions for a complex disease in a casecontrol study. We incorporate the quantitative genetic theory of high-order epistasis into the setting of cases and controls sampled from a natural population. The new model allows the identification and testing of epistasis and its various genetic components. Conclusions: Simulation studies were used to examine the power and false positive rates of the model under different sampling strategies. The model was used to detect epistasis in a case-control study of inflammatory bowel disease, in which five SNPs at a candidate gene were typed, leading to the identification of a significant three-locus epistasis