Estudio de la fermentación láctica para la extracción de quitina a partir de desechos de crustáceos

divpLa extracción de quitina a partir de desechos de crustáceos involucró la fermentación acido láctica para la desproteinización y desmineralización del caparazón de camarón, haciendo uso de suero de leche y sacarosa, como sustrato y fuente de carbono. El proceso de fermentación se llevo a cabo en un reactor vertical de vidrio Pyrex de 4 L por un período de 2 y 3 semanas a temperatura ambiente. Los resultados mostraron que aunque hubo una buena desproteinización y desmineralización, todavía el producto contenía restos de proteínas y pigmentos. Por ello, se hizo necesario aplicar un procedimiento químico con hidróxido de sodio e hipoclorito de sodio, para remover completamente las proteínas y los pigmentos de la estructura del caparazón. Al final del proceso se obtuvo una recuperación del 85 %. La comparación de los espectros FT-IR de la quitina producida con una muestra de quitina comercial, mostró un porcentaje de correlación del 93-95 %, lo que indica que la quitina obtenida utilizando el método combinado, tiene un alto grado de pureza./p pstrongPalabras claves:/strong Caparazón de camarón; Quitina; Reactor vertical; Sacarosa; Suero de leche/p pDOI: a href="http://dx.doi.org/10.5377/nexo.v24i1.592"http://dx.doi.org/10.5377/nexo.v24i1.592/a/p pNexo, Vol. 24, No. 1, pp. 33-42, 2011/p/di

Estudio de la fermentación láctica para la extracción de quitina a partir de desechos de crustáceos

The extraction of chitin from crustacean waste involved the deproteinisation and demineralisation of crustacean shells using lactic acid fermentation with whey and sucrose as culture medium and carbon source, respectively. The fermentation process was carried out in a vertical Pyrex reactor of 4 L by 2 and 3 weeks at room temperature. The results showed that a good deproteinisation and demineralisation was obtained; however, the product still contained traces of proteins and pigments. Therefore, it was necessary to apply a chemical process with sodium hydroxide and sodium hypochlorite, to completely remove the proteins and pigments from the structure of crustacean shell. A recovery of 85 % was obtained. The comparison of FT-IR spectra of chitin produced and a sample of commercial chitin showed a correlation rate of 93-95 %, indicating that chitin produced using the combined method has a high degree of purity. Keywords: Chitin; Shrimp shell; Sucrose; Vertical reactor; Whey DOI: http://dx.doi.org/10.5377/nexo.v24i1.592   Nexo, Vol. 24, No. 1, pp. 33-42, 2011La extracción de quitina a partir de desechos de crustáceos involucró la fermentación acido láctica para la desproteinización y desmineralización del caparazón de camarón, haciendo uso de suero de leche y sacarosa, como sustrato y fuente de carbono. El proceso de fermentación se llevo a cabo en un reactor vertical de vidrio Pyrex de 4 L por un período de 2 y 3 semanas a temperatura ambiente. Los resultados mostraron que aunque hubo una buena desproteinización y desmineralización, todavía el producto contenía restos de proteínas y pigmentos. Por ello, se hizo necesario aplicar un procedimiento químico con hidróxido de sodio e hipoclorito de sodio, para remover completamente las proteínas y los pigmentos de la estructura del caparazón. Al final del proceso se obtuvo una recuperación del 85 %. La comparación de los espectros FT-IR de la quitina producida con una muestra de quitina comercial, mostró un porcentaje de correlación del 93-95 %, lo que indica que la quitina obtenida utilizando el método combinado, tiene un alto grado de pureza. Palabras claves: Caparazón de camarón; Quitina; Reactor vertical; Sacarosa; Suero de leche   DOI: http://dx.doi.org/10.5377/nexo.v24i1.592   Nexo, Vol. 24, No. 1, pp. 33-42, 201

Diseño y montaje de una planta piloto para la extracción de quitina y proteínas

El proyecto se basó en el diseño y montaje de una planta piloto para la extracción química de Quitina y proteínas a partir de desechos de crustáceos (camarón y langostino). Se determinó el contenido de humedad del material y las condiciones experimentales óptimas de volumen y concentración de los reactivos involucrados en el proceso. Además, se realizó un análisis técnico y económico del mismo. Los resultados mostraron que la materia prima tiene un alto contenido de humedad entre 68-80% y que las condiciones experimentales para la obtención de Quitina dependen fuertemente de las características del material. Bajo estas condiciones se obtuvo una recuperación mayor del 98% para el caso de caparazón de camarón y de aproximadamente un 58% en el caso del langostino. Por otro lado, para la extracción de proteínas se encontró que la mayor producción ocurre a pH 4.0 y con soluciones provenientes del proceso de desproteinización, sin trituración previa de la materia prima. El estudio técnico proporcionó información básica sobre los costos e inversión del proceso operativo, datos sobre las instalaciones y los equipos asociados al proceso productivo. El análisis económico mostró que se debe tener una inversión inicial de US $10,520.94 para el montaje de la planta piloto y de US$ 4,852.58 para gastos de transporte y operación por seis meses. Palabras claves: caparazón de camarón; langostino; método químico; planta piloto; proteínas, quitina. DOI: http://dx.doi.org/10.5377/nexo.v22i2.42 Nexo: Revista Científica Vol. 22, No. 02, pp.45-55/Diciembre 200

Aplicación de quitosano modificado en el tratamiento de aguas residuales de tenerías

In this study, the adsorption capacity of chromium VI in copper-modified chitosan (Chitosan-Cu) and in zinc-modified chitosan (Chitosan-Zn), and its application in tannery wastewater were compared. This work included the study of the pH of maximum adsorption capacity in a range of 3 to 6 and the adsorption equilibrium of Cr (VI) at different concentrations (from 1.0 to 750.0 mg / l) and different masses of modified bio-adsorbents (5 and 2 g). The results showed that the adsorption of chromium VI in the two modified bioadsorbents depends strongly on the pH of the solution, where the highest percentage of chromium VI removal was reached at pH 3. The evaluation of the data Experiments of the adsorption equilibrium of Cr (VI) applying the Langmuir and Freundlich models shows that in all cases there was a better fit of the data to the Freundlich model and that the maximum adsorption capacity was reached in the Chitosan-Cu adsorbent. Also, the results indicated that the Chitosan-Cu adsorbent was more effective in the removal of Cr VI from tannery wastewater with 98%.En este estudio se comparó la capacidad de adsorción de cromo VI en quitosano modificado con cobre (Quitosano–Cu) y en quitosano modificado con cinc (Quitosano–Zn), y su aplicación en aguas residuales de tenería. Este trabajo incluyó el estudio del pH de máxima capacidad de adsorción en un rango de 3 a 6 y el equilibrio de adsorción de Cr (VI) a diferentes concentraciones (de 1.0 a 750.0 mg/l) y diferentes masas de bio-adsorbentes modificados (5 y 2 g). Los resultados muestran que la adsorción del ion metálico en los dos bio-adsorbentes modificados depende fuertemente del pH de la solución, donde el mayor porcentaje de remoción de cromo VI se alcanzó a pH 3. Por su parte, la evaluación de los datos experimentales del equilibrio de adsorción de Cr (VI), aplicando los modelos de Langmuir y Freundlich, mostró que en todos los casos hubo un mejor ajuste de los datos al modelo de Freundlich y que la capacidad máxima de adsorción fue alcanzada en el adsorbente Quitosano–Cu. Así también, los resultados indicaron que el adsorbente Quitosano–Cu fue más efectivo en la remoción de Cr VI de las aguas residuales de tenería con un 98%

Effect of the initial particle size distribution on the properties of suspension plasma sprayed Al2O3-TiO2 coatings

“NOTICE: this is the author’s version of a work that was accepted for publication in Surface & Coatings Technology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Surface & Coatings Technology, [268 (2015) 209-215] DOI 10.1016/j.surfcoat.2014.12.010¨Al2O3-TiO2 coatings have been deposited by atmospheric plasma spraying from agglomerated, nanostructured powders showing better properties than those of their conventional (microstructured) counterparts. These nanostructured coatings can be also obtained by suspension plasma spraying however the research on suspension plasma sprayed Al2O3-TiO2 is still scarce. Consequently, it is crucial to study the effect of the suspension characteristics on the coating properties and to optimize the deposition process. In this work, Al2O3-13 wt.% TiO2 tribological coatings were successfully deposited by suspension plasma spraying from three different feedstocks: a nanometric suspension and two bimodal suspensions with different solid contents made up of titania nanoparticles and alumina submicron-sized particles. The coating microstructure and phase composition were characterized using scanning electron microscopy and X-ray diffraction analysis. Moreover, nanoindentation technique was used to determine the nanomechanical properties of coatings. The influence of the feed suspension characteristics on the final coating quality was analyzed. Findings showed that similar microstructures and phases were developed after depositing the different feedstocks. In addition suspension feedstock made up of nanoparticles resulted in a coating with better mechanical properties. However the use of submicron-sized particles in the suspension feedstocks gives rise to some technical and economic advantages in the process which should be taken into account when a suspension plasma spraying process is to be setup. (C) 2014 Elsevier B.V. All rights reserved.This work has been supported by the Spanish Ministry of Science and Innovation (project MAT2012-38364-C03) and it has been co-funded by ERDF (European Regional Development Funds).Vicent, M.; Bannier, E.; Carpio, P.; Rayón Encinas, E.; Benavente Martínez, R.; Salvador Moya, MD.; Sánchez, E. (2015). Effect of the initial particle size distribution on the properties of suspension plasma sprayed Al2O3-TiO2 coatings. Surface and Coatings Technology. 268:209-215. https://doi.org/10.1016/j.surfcoat.2014.12.010S20921526

Impact of Feedstock Nature on Thermal Conductivity of YSZ Thermal Barrier Coatings Obtained by Plasma Spraying

[EN] Yttria-stabilized zirconia (YSZ) coatings with low thermal conductivity were obtained using three different particle size distributions as starting powder: nano-, submicron- and bimodal submicron/nano-sized particles. On the one hand, these particles were reconstituted into micrometric, spray-dry agglomerates, which were subsequently deposited by means of conventional atmospheric plasma spraying (APS). On the other hand, the starting particles were dispersed in water and the resultant suspensions were deposited by means of suspension plasma spraying (SPS). The coatings were thermally treated to assess their sintering resistance. As-sprayed and thermally treated coatings were then characterized in terms of microstructure (FEG-SEM) and thermal diffusivity (laser flash equipment). The results showed that SPS coatings exhibited extremely low thermal conductivity at low temperature which drastically augmented with increasing temperature. On the other hand, APS coatings also exhibited low thermal conductivities but their values were higher than those of the SPS coatings at the lowest temperature tested while the conductivities hardly varied with temperature.This work has been supported by the Spanish Ministry of Economy and Competitiveness (project MAT2015-67586-C3-R) and Research Promotion Plan of the Universitat Jaume I, action 2.1 (ref. E-2011 - 05) and action 3.1 (ref. PREDOC/2009/10). A. Borrell acknowledges the Spanish Ministry of Economy and Competitiveness for her Juan de la Cierva-Incorporacion contract (IJCI-2014-19839). M. Miranda would like to thank the European Commission (FP7-Marie Curie Intra-European Fellowship, BIOHYMAT).Carpio-Cobo, P.; Salvador Moya, MD.; Benavente Martínez, R.; Miranda, M.; Borrell Tomás, MA.; Sánchez, E. (2016). Impact of Feedstock Nature on Thermal Conductivity of YSZ Thermal Barrier Coatings Obtained by Plasma Spraying. Journal of Ceramic Science and Technology. 7(3):307-312. https://doi.org/10.4416/JCST2016-00022S3073127

CDK2 regulates nuclear envelope protein dynamics and telomere attachment in mouse meiotic prophase

In most organisms, telomeres attach to the nuclear envelope at the onset of meiosis to promote the crucial processes of pairing, recombination and synapsis during prophase I. This attachment of meiotic telomeres is mediated by the specific distribution of several nuclear envelope components that interact with the attachment plates of the synaptonemal complex. We have determined by immunofluorescence and electron microscopy that the ablation of the kinase CDK2 alters the nuclear envelope in mouse spermatocytes, and that the proteins SUN1, KASH5 (also known as CCDC155) and lamin C2 show an abnormal cap-like distribution facing the centrosome. Strikingly, some telomeres are not attached to the nuclear envelope but remain at the nuclear interior where they are associated with SUN1 and with nuclear-envelope-detached vesicles. We also demonstrate that mouse testis CDK2 phosphorylates SUN1 in vitro. We propose that during mammalian prophase I the kinase CDK2 is a key factor governing the structure of the nuclear envelope and the telomere-led chromosome movements essential for homolog pairin

Effects of the 4N(v) chromosome from Aegilops ventricosa on agronomic and quality traits in bread wheat

Advanced wheat lines carrying the Hessian fly resistance gene H27 were obtained by backcrossing the wheat/Aegilops ventricosa introgression line, H-93-33, to commercial wheat cultivars as recurrent parents. The Acph-N v 1 marker linked to the gene H27 on the 4Nv chromosome of this line was used for marker assisted selection. Advanced lines were evaluated for Hessian fly resistance in field and growth chamber tests, and for other agronomic traits during several crop seasons at different localities of Spain. The hessian fly resistance levels of lines carrying the 4Nv chromosome introgression (4D/4Nv substitution and recombination lines that previously were classified by in situ hybridisation) were high, but always lower than that of their Ae. ventricosa progenitor. Introgression lines had higher grain yields in infested field trials than those without the 4Nv chromosome and their susceptible parents, but lower grain yields under high yield potential conditions. The 4Nv introgression was also associated with later heading, and lower tiller and grain numbers/m2 . In addition, it was associated with longer and more lax spikes, and higher values of grain weight and grain protein content. However, the glutenin and gliadin expression, as well as the bread-making performance, were similar to those of their recurrent parent

Prognostic classification for malignant tumors of the parotid gland

AbstractObjectiveThe histological classification of the World Health Organization (WHO), along with improved imaging studies, provide relevant information for the management of parotid carcinomas. However, the prognosis depends on factors other than histology and tumor extension. This article evaluates the usefulness of a prognostic classification of parotid cancers, including these factors in patients in a hospital area.MethodsA follow-up was conducted on 19 patients with parotid carcinomas, excluding lymphoid tumors or intra-parotid metastases, between 1998 and 2012. The prognostic index was obtained from the formulas proposed by Vander Poorten, with factors including age, tumor size, lymph node involvement, skin invasion, facial nerve involvement, perineural growth and margins of resection, before surgery (PS1) and after (PS2). Overall survival was related to 5 years for each patient based on their inclusion in any of the 4 risk groups defined.ResultsRisk stratification based on the results Vander Poorten PS2 was distributed into Risk Groups (GR) 1 (3 patients, 15.7%), 2 (5 patients, 26.3%), 3 (1 patient, 5.8%) and 4 (10 patients, 52.2%). The 6 patients who died during follow-up belonged to GR4. Only one of the 4 patients belonging to GR4 has exceeded the 5-year survival up to the current time.The comparison of the values that relate the pretreatment (PS1) and after treatment (PS2) results showed overall survival in patients with PS1<4.5 and PS2<4.9, whereas mortality was greater with indices of PS1>6.5 and PS2>7.7.ConclusionsVander Poorten index can be applied in hospital areas with small numbers of parotid carcinomas. It enables a more accurate prognosis for individual patients

Influence of the feedstock characteristics on the microstructure and properties of Al2O3 TiO2 plasma-sprayed coatings

[EN] Atmospheric plasma spraying (APS) is an interesting technique to obtain nanostructured coatings due to its versatility, simplicity and relatively low cost. However, nanometric powders cannot be fed into the plume using conventional feeding systems, due to their low mass and poor flowability, and must be adequately reconstituted into sprayable micrometric agglomerates. In this work, Al2O3–13 wt.%TiO2 nanostructured and submicron-nanostructured powders were deposited using APS. The feedstocks were obtained by spray drying from two starting suspensions, prepared by mixing two commercial nanosuspensions of Al2O3 and TiO2, or by adding nanosized TiO2 and submicron-sized Al2O3 powders to water. The spray-dried granules were heat-treated to reduce their porosity and the resultant powders were fully characterized. Optimization of the deposition conditions enabled the reconstituted powders to be successfully deposited, yielding coatings that were well bonded to the substrate. The coating microstructure, characterized by SEM, was formed by semi-molten feedstock agglomerates surrounded by fully molten particles that act as a binder. Moreover, microhardness, adhesion, and tribological behavior were determined, and the impact of the granule characteristics on these properties was studied. It was found that changing the feedstock characteristics allowed controlling the coating quality and properties.This work has been supported by the Spanish Ministry of Science and Innovation (project MAT2009-14144-C03).Vicent, M.; Bannier, E.; Benavente Martínez, R.; Salvador Moya, MD.; Molina, T.; Moreno, R.; Sánchez, E. (2013). Influence of the feedstock characteristics on the microstructure and properties of Al2O3 TiO2 plasma-sprayed coatings. Surface and Coatings Technology. 220:74-79. https://doi.org/10.1016/j.surfcoat.2012.09.042S747922