Sensorial and physicochemical quality responses of pears (cv Rocha) to long-term storage under controlled atmospheres

Pears (cv Rocha) kept under controlled atmospheres (CA) and air were evaluated after longterm storage in terms of sensory attributes and physicochemical parameters, namely colour, firmness, polyphenoloxidase (PPO) activity and concentration of hydroxycinnamic compounds. The CA conditions were all combinations of 2 and 4% (v/v) O2 with 0.5 and 1.5% (v/v) CO2. Storage under CA conditions produced a beneficial effect on ‘Rocha’ pears in maintaining their quality and, consequently, in extending their shelf life and acceptability. Clear differences in sensorial attributes, colour parameters and PPO activity were found between CA- and air-stored pears. The effect provided by the CA conditions persisted throughout the time of exposure to the open air. The 2%O2 concentration produced amore beneficial effect than its 4%counterpart on the sensorial and physical characteristics of the pears.The former concentration of O2 prevented yellowing and allowed regular softening, hence keeping a high flavour quality. No clear effects could be associated with CO2 levels. Empirical models were developed that describe the effects of O2 and CO2 concentrations, as well as time at room temperature on physicochemical parameters pertaining to ‘Rocha’ pears

Scale-invariant magnetoresistance in a cuprate superconductor

The anomalous metallic state in high-temperature superconducting cuprates is masked by the onset of superconductivity near a quantum critical point. Use of high magnetic fields to suppress superconductivity has enabled a detailed study of the ground state in these systems. Yet, the direct effect of strong magnetic fields on the metallic behavior at low temperatures is poorly understood, especially near critical doping, $x=0.19$. Here we report a high-field magnetoresistance study of thin films of \LSCO cuprates in close vicinity to critical doping, $0.161\leq x\leq0.190$. We find that the metallic state exposed by suppressing superconductivity is characterized by a magnetoresistance that is linear in magnetic field up to the highest measured fields of $80$T. The slope of the linear-in-field resistivity is temperature-independent at very high fields. It mirrors the magnitude and doping evolution of the linear-in-temperature resistivity that has been ascribed to Planckian dissipation near a quantum critical point. This establishes true scale-invariant conductivity as the signature of the strange metal state in the high-temperature superconducting cuprates.Comment: 10 pages, 3 figure

Design of an electroflotation system for the concentration and harvesting of freshwater microalgae

Microalgae are considered as one of the most promising alternatives for the integrated use of agro-industrial water residues and the production of metabolites of high industrial interest. This is due to algae can grow on wastewater which in turn can reduce the emission of nutrients to rivers and lakes. However, the greatest scientific-technological barrier is the concentration and separation of the biomass produced. There are several processes used at different levels (from laboratory to industrial scale) such as flocculation, centrifugation, flotation, etc. These can be very expensive or can (possibly) contaminate the biomass. Unlike the previous ones, electroflotation has been proposed as a cost-efficient method, nevertheless its final efficiency will depend heavily on the type of alga and culture medium. Taking into account the above, the present project aims to design an electroflotation system for the concentration and harvest of microalgae biomass. The effect of several factors (pH, time, voltage and distance between the electrodes) and for types of materials (Copper, Aluminium, Iron and Steel) on biomass recovery efficiency from a culture of Chlorella vulgaris UTEX 1803 was evaluated by the implementation of a Design of experiments (43 non-factorial design) using STATISTICA 7.0. Results show that, the materials with higher concentration efficiency were cooper and aluminium with 40 and 80% respectively, and the most relevant factors were distance between electrodes (1-2 cm), time (>20 min) and Voltage (>15V). In order to increase the efficiency of the overall process a new 43 experimental factorial design was proposed using as factors distance between electrodes, time, voltage and agitation. Results show that agitation positively affects the total efficiency until reaching a total concentration of the biomass (100%). It was found that a voltage close to 50V and a time greater than 25 min positively affect the final efficiency of the copper and aluminium electrodes, however aluminium has the highest efficiency (> 95%) compared to copper (<85%)

The hibernating South American marsupial, Dromiciops gliroides, displays torpor-sensitive microRNA expression patterns

When faced with adverse environmental conditions, the marsupial Dromiciops gliroides uses either daily or seasonal torpor to support survival and is the only known hibernating mammal in South America. As the sole living representative of the ancient Order Microbiotheria, this species can provide crucial information about the evolutionary origins and biochemical mechanisms of hibernation. Hibernation is a complex energy-saving strategy that involves changes in gene expression that are elicited in part by microRNAs. To better elucidate the role of microRNAs in orchestrating hypometabolism, a modified stem-loop technique and quantitative PCR were used to characterize the relative expression levels of 85 microRNAs in liver and skeletal muscle of control and torpid D. gliroides. Thirty-nine microRNAs were differentially regulated during torpor; of these, 35 were downregulated in liver and 11 were differentially expressed in skeletal muscle. Bioinformatic analysis predicted that the downregulated liver microRNAs were associated with activation of MAPK, PI3K-Akt and mTOR pathways, suggesting their importance in facilitating marsupial torpor. In skeletal muscle, hibernation-responsive microRNAs were predicted to regulate focal adhesion, ErbB, and mTOR pathways, indicating a promotion of muscle maintenance mechanisms. These tissue-specific responses suggest that microRNAs regulate key molecular pathways that facilitate hibernation, thermoregulation, and prevention of muscle disuse atrophy.Link_to_subscribed_fulltex

Production of chlorella vulgaris biomass on uv-treated wastewater as an alternative for environmental sustainability on high-mountain fisheries

The sustained expansion of agricultural industry in Colombian high-mountain has led to an increased size of residues, especially untreated wastewater. This untreated water is an urgent matter for public and environmental health, not only by its nutrient concentration (composed especially of food residuals and feces) but also the presence of pathogens (virus, bacteria, etc.) which are discharged to the environment. The overall objective of this work is to evaluate the effect of UV-treated wastewater from a high-mountain fishery as culture media for the production of Chlorella vulgaris as a sustainable method for nutrient and water recirculation on the fishery production system. The UV-canal efficiency was evaluated by the implementation of an experimental factorial design (time, distance of the UV-lamps towards the canal, number of UV-lamps and the sample concentration) using STATISTICA 7.0 software. Results shown that time (3 to 5 minutes) and the number of lamps (3-4) of 15 Watts eliminate completely coliforms from the samples. After UV-treatment the resulting water was test as culture media for C. vulgaris production by the adjustment of C/N ratio (Sodium Carbonate/potassium nitrate) by the implementation of an experimental 23 factorial design. Results shown that higher nitrate concentrations (>0,22 g/L) and moderate carbonate concentrations (1 g/L) increase the final biomass concentration up to 4g/L in 20 days

Aislamiento y serotipificación de Pasteurella haemolytica en ovinos.

Uno de los factores limitantes para el desarrollo de la industria ovina en Colombia, es el deficiente conocimiento acerca de las enfermedades que afectan esta especie. En países ovinocultores por tradición, la mayoría de los brotes de septicemia y neumonía han sido asociados con Pasteurella haemolytica, causando grandes pérdidas económicas debido a pérdida de peso y muerte. Por primera vez se realizó en el país un estudio para determinar la prevalencia de portadores sanos de Pasteurella haemolytica en ovinos del valle de Sogamoso y estaciones experimentales en los departamentos de Cundinamarca y Boyacá, durante el período 1981-1982. Para tal efecto se colectaron 608 muestras de hisopos nasofaríngeos y 92 tonsilas, de acuerdo con un modelo estadístico de distribución binomial. Las muestras fueron sembradas en agar sangre de ovino y agar McConkey confirmando luego la presencia de Pasteurella haemolytica por pruebas culturales y bioquímicas. Mediante el empleo de cepas de referencia, suministradas por el Instituto Moredun (Escocia), se prepararon antisueros específicos para efectuar la clasificación serológica de los aislamientos de campo. Esta clasificación se llevó a cabo por pruebas de hemaglutinación pasiva (HI) y aglutinación rápida en placa (ARP). La prevalencia de portadores sanos fue de 18,71 por ciento (P menor que 0,05). El serotipo más común fue el A5 (43,5 por ciento), seguido por A9 (22,1 por ciento), A2 (17,6 por ciento), A7 (8,4 por ciento, A13 (2,3 por ciento) y A11 (1,5 por ciento). No se efectuó ningún aislamiento del biotipo T. La presencia de P. haemolytica biotipo A, tiene un gran significado epidemiológico puesto que este biotipo está asociado con presentación de neumonía en ovejas adultas y septicemia en jóvenes. Se discute la importancia de la enfermedad en las áreas ovino-cultoras en relación con las condiciones de manejo y la prevalencia del virus de Parainfluenza tipo 3Ovinos-Ganado ovino - Ovis arie

Perfiles metabólicos en ovinos del valle de Sogamoso

En nueve municipios del Valle de Sogamoso, departamento de Boyacá. Se realizó un estudio con el objeto de determinar los perfiles metabólicos de ovinos criollos bajo condiciones naturales de explotación. De acuerdo con un diseño de distribución binomial se analizaron 232 muestras de sangre de ovinos en 44 veredas del área bajo estudio. En cada una de las muestras se determinaron los niveles de hematocrito, hemoglobina, calcio, fósforo inorgánico, magnesio, cobre, glucosa, proteína total y albúmina. Los resultados fueron promediados, se determinó el error estándar respectivo y las variaciones entre sexo y edad se establecieron por análisis de varianza. Los parámetros estudiados mostraron en algunos casos niveles comparables a los valores existentes en la literatura pero algunos de ellos como el calcio - fósforo, cobre y la albúmina se encontraron en concentraciones menores a las consideradas normales. Estas y otras diferencias establecidas con relación al sexo y la edad quizás se expliquen por las pobres condiciones dietéticas a las cuales son sometidos los ovinos en el país y por las variaciones estacionales que afectan la disponibilidad de nutrientes en el forraje. Se concluye que estos valores son de utilidad para establecer comparaciones con investigaciones futuras tanto en el área de nutrición como en la de patología de los ovinos.A study in nine areas of the Sogarnoso Valley (Bayacá, Colombia) was carried out to determine the metabolic profiles in native sheep under natural management conditions. According to a binomial design 232 blood samples were collected from the areas under study. Each sample was analized to establish the levels of hematacrit, hemoglobin, calcium, phosphorus, magnesium, copper, glucose, total protein and albumin. 63 Means and standard error of each value were determined and analyses of variance were performed to establish the differences between ages and sexes. The parameters studied showed similar values to those reported in the literature but calcium, phosphorus and albumin were low in relation with those considered normal. These differences may be explained as due to the undernutrition in free grazing sheep resulting from seasonal variation of nutrients in the pasture. It is concluded that these values will be useful as reference for future studies on pathologic and nutritional problems of native sheep in Colonibia.Ovinos-Ganado ovino - Ovis arie

Serologic prevalence of caprine arthritis encephalitis virus in goat populations of Cundinamarca, Colombia

Serologic prevalence of caprine arthritis encephalitis (CAE) virus was determined in 15 villages of Cundinamarca, Colombia by agar gel immunoditfusion test using Gp 135 reference protein. A sample of 200 serums was obtained according to a binomial design from 21 goat populations in the selected area. Positive reactors were detected in 26.5% of the tested animals and 14 out of 21 goat populations had positive animals. A significative association (P ≤ 0.01) was founded between infection, male sex, pure breed and breed crosses. No association was detected between prevalence and age. Prevention and control mesures against the disease are suggested.En 15 municipios de Cundinamarca (Colombia) se estudió la prevalencia serológica de Artritis Encefalitis Caprina (AEC) por la técnica de inmunodifusión en gel, utilizando como antígeno de referencia la proteína Gp 135. La muestra de 200 sueros se obtuvo mediante la aplicación de un modelo de distribución binomial en 21 apriscos del área estudiada. Se estableció que el 26.5% de los caprinos eran reactores positivos a la infección, que 14 de los 21 apriscos contenían animales reactores y que la prevalencia de la infección estaba asociada significativamente (P ≤ 0.01) con los machos y con las razas puras y sus cruces, mientras que no se encontró asociación entre la prevalencia y la edad de los animales. Finalmente, se sugieren algunas medidas encaminadas a la prevención y control de la enfermedad