Implications of storage and handling conditions on glass transition and potential devitrification of oocytes and embryos

Devitrification, the process of crystallization of a formerly crystal-free, amorphous glass state, can lead to damage during the warming of cells. The objective of this study was to determine the glass transition temperature of a cryopreservation solution typically used in the vitrification, storage, and warming of mammalian oocytes and embryos using differential scanning calorimetry. A numerical model of the heat transfer process to analyze warming and devitrification thresholds for a common vitrification carrier (open-pulled straw) was conducted. The implications on specimen handling and storage inside the dewar in contact with nitrogen vapor phase at different temperatures were determined. The time required for initiation of devitrification of a vitrified sample was determined by mathematical modeling and compared with measured temperatures in the vapor phase of liquid nitrogen cryogenic dewars. Results indicated the glass transition ranged from -126°C to -121°C, and devitrification was initiated at -109°C. Interestingly, samples entered rubbery state at -121°C and therefore could potentially initiate devitrification above this value, with the consequent damaging effects to cell survival. Devitrification times were calculated considering an initial temperature of material immersed in liquid nitrogen (-196°C), and two temperatures of liquid nitrogen vapors within the dewar (-50°C and -70°C) to which the sample could be exposed for a period of time, either during storage or upon its removal. The mathematical model indicated samples could reach glass transition temperatures and undergo devitrification in 30seconds. Results of the present study indicate storage of vitrified oocytes and embryos in the liquid nitrogen vapor phase (as opposed to completely immersed in liquid nitrogen) poses the potential risk of devitrification. Because of the reduced time-handling period before samples reach critical rubbery and devitrification values, caution should be exercised when handling samples in vapor phase.Fil: Sansinena, Marina Julia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires"; ArgentinaFil: Santos, Maria Victoria. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Taminelli, Guillermo Luis. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires"; ArgentinaFil: Zaritzky, Noemi Elisabet. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentin

Implications of storage and handling conditions on glass transition and potential devitrification of oocytes and embryos

Devitrification, the process of crystallization of a formerly crystal-free, amorphous glass state, can lead to damage during the warming of cells. The objective of this study was to determine the glass transition temperature of a cryopreservation solution typically used in the vitrification, storage, and warming of mammalian oocytes and embryos using differential scanning calorimetry. A numerical model of the heat transfer process to analyze warming and devitrification thresholds for a common vitrification carrier (open-pulled straw) was conducted. The implications on specimen handling and storage inside the dewar in contact with nitrogen vapor phase at different temperatures were determined. The time required for initiation of devitrification of a vitrified sample was determined by mathematical modeling and compared with measured temperatures in the vapor phase of liquid nitrogen cryogenic dewars. Results indicated the glass transition ranged from -126°C to -121°C, and devitrification was initiated at -109°C. Interestingly, samples entered rubbery state at -121°C and therefore could potentially initiate devitrification above this value, with the consequent damaging effects to cell survival. Devitrification times were calculated considering an initial temperature of material immersed in liquid nitrogen (-196°C), and two temperatures of liquid nitrogen vapors within the dewar (-50°C and -70°C) to which the sample could be exposed for a period of time, either during storage or upon its removal. The mathematical model indicated samples could reach glass transition temperatures and undergo devitrification in 30seconds. Results of the present study indicate storage of vitrified oocytes and embryos in the liquid nitrogen vapor phase (as opposed to completely immersed in liquid nitrogen) poses the potential risk of devitrification. Because of the reduced time-handling period before samples reach critical rubbery and devitrification values, caution should be exercised when handling samples in vapor phase.Fil: Sansinena, Marina Julia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires"; ArgentinaFil: Santos, Maria Victoria. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Taminelli, Guillermo Luis. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires"; ArgentinaFil: Zaritzky, Noemi Elisabet. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentin

Coordinación motriz y habilidades sociales en niños de cuatro y cinco años de una institución educativa de Lima, 2023

La coordinación motriz en los niños es un punto importante en su desarrollo cognitivo, porque es allí donde subyace la motricidad fina, gruesa y el equilibrio. Mientras que las habilidades sociales se refieren a las conductas o actitudes que adquiere el individuo a lo largo de su crecimiento, y logra la interacción con la sociedad. Por tal razón surge está investigación con el propósito de determinar la relación que existe entre la coordinación motriz y las habilidades sociales en los niños de cuatro y cinco años de una institución educativa de Lima. Teniendo como metodología un enfoque cuantitativo, de nivel correlacional con diseño no experimental, utilizando como muestra 100 niños. Para ello se aplicó una escala estimativa. Los resultados reportaron en la hipótesis general que existe una correlación positiva alta (r=0.736) y un nivel de logro esperado de 53%. En cuanto a las hipótesis especificas se evidenció que la correlación fue positiva y significativa entre la coordinación motriz y las habilidades primaria (r=0, 848), las habilidades habilidades intermedias (r=0,711) y las habilidades superiores (r= 0,687) Se concluye que existe correlación positiva y significativa entre la coordinación motriz y las habilidades sociales de los niños de cuatro y cinco años

Runaway stars as cosmic ray injectors inside molecular clouds

Giant molecular clouds (GMCs) are a new population of gamma-ray sources, being the target of cosmic rays (CRs) -- locally accelerated or not --. These clouds host very young stellar clusters where massive star formation takes place. Eventually, some of the stars are ejected from the clusters, becoming runaway stars. These stars move supersonically through the cloud and develop bowshocks where particles can be accelerated up to relativistic energies. As a result, the bowshocks present non-thermal emission, and inject relativistic protons in the cloud. These protons diffuse in the GMC interacting with the matter. We present a model for the non-thermal radiation generated by protons and secondary pairs accelerated in the bowshocks of massive runaways stars within young GMCs. We solve the transport equation for primary protons and secondary pairs as the stars move through the cloud. We present non-thermal emissivity maps in radio and in gamma rays as a function of time. We obtain X-ray luminosities of the order $\sim$ ${ 10^{32}}$ erg~s$^{-1}$ and gamma-ray luminosities $\sim$ $10^{34}$ erg~s$^{-1}$. We conclude that, under some assumptions, relativistic protons from massive runaway stars interacting with matter in GMCs give rise to extended non-thermal sources.Comment: 16 pages, 10 figures, accepted for publication in MNRA

Determination of heat transfer coefficients of biological systems during cooling in liquid nitrogen under film and nucleate pool boiling regimes

The cryopreservation process consists of reducing the temperature of the sample to a point where biological stability is achieved. In particular the measurement of the temperature change of the sample is important to calculate cooling rates and to determine if a sample is vitrified or undergoes phase change transition. As soon an object is plunged into liquid nitrogen it enters into a film boiling regime due to the large temperature difference between the object and the liquid nitrogen (LN2). This determines a heat flux from the object to LN2 causing the latter to boil in the immediate vicinity of the object and creating a pocket of nitrogen vapor around the object which acts as an “insulator” and retards further heat transfer. Film boiling is also referred to as the “Leidenfrost effect”. Boiling curves for a specific cryobiological system are scarcely found in the literature due to the small dimensions of the devices used in the process and the experimental limitations. The experimental information such as the time-temperature curve allows the prediction of the surface heat transfer coefficients that govern the cooling process: film, transition and nucleate boiling. In order to predict the surface heat transfer coefficient for each boiling regime the mathematical modeling of the partial differential equations that represent the energy transfer must be implemented, applying convective boundary conditions. In this work the different heat transfer coefficients and the boiling curve of straws filled with ice (at an initial temperature between -2ºC to -9ºC) were experimentally measured when they were immersed in liquid nitrogen; this allowed to determine the existence of different boiling regimes. The application of a numerical finite element program using the software COMSOL was used to predict time-temperature curves and to obtain the surface heat transfer coefficients that control each boiling regime. Independent experiments were carried out using straws that contained a biological fluid (semen+extender), which were initially at room temperature, to further validate the different surface heat transfer coefficients for film and nucleate pool boiling. The program takes into account the variable thermo-physical properties of the biological sample. This constitutes a highly non-linear mathematical problem, as the freezing process evolves with a variable surface heat transfer coefficients as the different boiling regimes occur. The program was experimentally validated contrasting experimental temperatures vs. time with numerical predictions. The numerical program is an important tool in order to correctly assess the heat transfer process and optimize the cryopreservation of straws filled with biological fluids.Fil: Santos, Maria Victoria. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Sansinena, Marina Julia. Pontificia Universidad Catolica Argentina "Santa Maria de Los Buenos Aires". Facultad de Ciencias Agrarias; ArgentinaFil: Chirife, Jorge. Pontificia Universidad Catolica Argentina "Santa Maria de Los Buenos Aires". Facultad de Ciencias Agrarias; ArgentinaFil: Zaritzky, Noemi Elisabet. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentin

Groundwater quality comparison between rural farms and riparian wells in the western Amazon, Brazil

Groundwater quality of a riparian forest is compared to wells in surrounding rural areas at Urupá River basin. Groundwater types were calcium bicarbonated at left margin and sodium chloride at right, whereas riparian wells exhibited a combination of both (sodium bicarbonate). Groundwater was mostly solute-depleted with concentrations within permissible limits for human consumption, except for nitrate. Isotopic composition suggests that inorganic carbon in Urupá River is mostly supplied by runoff instead of riparian groundwater. Hence, large pasture areas in addition to narrow riparian forest width in this watershed may have an important contribution in the chemical composition of this river.FAPESPCNPq - CT-HIDROCNPq - Milêni

CARBON AND NITROGEN IN SOILS AND HUMIC FRACTIONS OF DIFFERENT PEDOFORMS IN THE ATLANTIC FOREST BIOME

Relief is a soil formation factor that can modify the distribution of soil organic matter (SOM) fractions in a landscape. The objective of this study was to evaluate the effect of the relief on SOM fractions, considering their distribution in different topographic positions, segments, in two pedoforms (concave and convex) in areas covered with forest in the Atlantic Forest biome. The two pedoforms were selected in adjacent areas and divided into segments considering the topographic variation. The carbon and nitrogen origins were evaluated in the extract up to 100 cm of depth. Soil samples from the 0-5, 5-10, and 10-20 cm layers were collected for chemical characterization and fractioning (granulometric and chemical) of the SOM. The soil density in the 0-5 and 5-10 cm layers was determined to calculated the carbon stocks. The isotopic composition showed predominance of 13C. The highest organic carbon and particulate carbon contents were found in the convex pedoform. The distribution of humic fractions showed that the larger part of the humidified carbon was in the humin fraction. The humin and fulvic acid fractions were higher in the convex pedoform. The carbon stocks were, in general, higher in the convex pedoform, decreasing as the soil depth increased; and nitrogen stocks presented no differences. The higher carbon and nitrogen contents were found in the convex pedoform and in the lower region of the concave pedoform

Desestabilización de emulsiones petróleo/agua mediante la aplicación del biopolimero quitosano

La industria petrolera genera grandes cantidades de efluentes emulsionados; el uso de biopolímeros que puedan desestabilizar estas emulsiones y clarificar el agua para su posterior volcado resulta una alternativa tecnológica importante. Quitosano (QS) es un polisacárido lineal que se obtiene de desechos sólidos de la industria pesquera. Es un biopolímero no-tóxico, biodegradable y presenta grupos amino libres que le confieren un carácter de poli-electrolito catiónico natural, ideal para generar la floculación/coagulación en emulsiones estables. Los objetivos de este trabajo son: (a) estudiar la acción del QS para la clarificación de efluentes emulsionados, (b) analizar en un sistema modelo de efluente con petróleo, agua y un tensioactivo aniónico biodegradable (dodecil sulfato de sodio, SDS), la turbidez residual (%TR) de la fase acuosa en función de la dosis de QS, (c) describir el fenómeno de la desestabilización de emulsiones utilizando distintas técnicas como: mediciones de %TR, demanda química de oxígeno, mediciones ópticas (Turbiscan) y potencial zeta, (d) aplicar la metodología de superficie de respuesta (MSR) para predecir el punto óptimo de clarificado a partir de la dosis de QS y concentración de SDS. Las emulsiones estables se prepararon con crudo de petróleo y SDS; la MSR se aplicó utilizando un modelo central compuesto. Se midió el %TR variando la concentración de SDS (rango inferior a la concentración micelar crítica, 2.09-4.9 mM) y dosis de QS (0,247-1,429 g/L). Los resultados obtenidos indican que el QS es un potente agente desestabilizador de acción rápida (<3hrs) y una opción sustentable para el tratamiento de efluentes.Fil: Perez Calderon, John Freddy. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Santos, Maria Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales. Universidad Nacional del Comahue. Instituto Andino Patagónico de Tecnologías Biológicas y Geoambientales.; ArgentinaFil: Zaritzky, Noemi Elisabet. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentin

HSE Management for a Sound Work Environment: Strategies for Improving Health Safety and Environmental Indicators through Ergonomic Design Thinking

Ergonomic Design Thinking (EDT) is a project management methodology that takes advantage of two important concepts or themes in carrying out project actions. The first is Design Thinking itself, a project management approach originally proposed by Tim Brown, who knew beforehand the full potential of design tools, techniques and maybe we should add idiosyncrasies. Designers have “their own way” of following through and carrying out issues such as deadlines and sequences, for example. This logic is similar to another important theme: ergonomics. The main objective of ergonomics is adapting work systems to workers themselves. By doing so, its professionals dig deep into the social technical fabric of a workplace and use recurrent and iterative strategies in order to search for a perfect fit for a given workstation. EDT as a modeling guide for workspace projects have been used in Brazil for quite some time. This text outlines an interesting experience in which EDT was used as a conception tool in building a new health safety and environmental (HSE) management system model for construction sites. A real case–an ongoing construction work–was used to contextualize the experiment and better define the various instruments of this HSE model. Due to the work environment and predominant job characteristics available, the EDT approach did quite well in terms of serving its project management purpose, as it was confirmed when the new system became fully functional