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[en] Glycerol is used in many applications of science and daily life as it is cheap and biologically non-invasive. In science, aqueous solutions of glycerol are commonly used for experimental investigations as their density can be adapted by changing the glycerol content in the solution. Although the density of aqueous glycerol solutions has been measured precisely since more than a century, current models show a deviation from measured data of up to . In this work we present an analytical expression to accurately calculate the density of aqueous glycerol solutions. The presented empirical model is validated in the range between 15 and and has a maximum deviation of less than with respect to measured data. This improves the accuracy of current models by more than one order of magnitude. By knowing the temperature and glycerol content of the solution, its density can be simply calculated with the presented model. A Matlab function is provided in the supplementary material to allow a simple implementation in other scientific work.
[en] Glycerol is the main by-product of bio diesel production that produces from transesterification process. In this research, focused was on hydrogen production via glycerol steam reforming using nickel loaded HZSM-5 catalyst. The catalysts were prepared by using different loading amount of nickel (0.5, 1.0, 5.0, 10.0 and 15 wt %) on HZSM-5 catalyst through the wet impregnation method at temperature 500 degree Celsius and atmospheric pressure. The catalyst was characterized by using XRD, FTIR and SEM. Then, only 15 wt % Ni loading has been chosen based on the parameter which is different range of catalyst weight (0.3-0.5 g) at different range of glycerol flow rate (0.2-0.4mL/ min) at temperature 600 degree Celsius and atmospheric pressure. The products were analyzed by using gas-chromatography with thermal conductivity detector (GC-TCD) where it is used to identify the yield of hydrogen. The data of the experiment were analyzed by using Response Surface Methodology (RSM) in order to study the relationship of catalyst weight and glycerol flow rate. The results showed that the optimum condition to produce a maximum hydrogen yield with 15 wt % Ni/ HZSM-5 catalyst was 78.10004 % at glycerol flow rate of 0.356484 mL/ min and catalyst weight of 0.429267 g. (author)
[en] The characteristics of centrifugal pump performance according to fluid viscosity change were studied experimentally. A small volute pump with low specific speed was tested by changing the viscosity of an aqueous solution of sugar and glycerin, which is considered a Newtonian fluid. After finishing the test, the total head, shaft horsepower, and pump efficiency were compared with those of a water pump. The results are summarized as follows: when the fluid viscosity is increased, the shut-off head shows very little change but the total head decreases gradually as the flow increases, and this makes the H-Q curve leaning rapidly, and when the fluid viscosity is increased, the shaft horsepower shows very little change at the shutoff condition; however, the shaft horsepower increases more rapidly with an increase in the flow and viscosity
[en] Graphical abstract: - Abstract: Poly(3,4-ethylenedioxythiophene) (PEDOT) supported PdRu catalysts with various Pd:Ru atomic ratios are prepared by one step electrodeposition method. The catalysts are characterised by several physicochemical techniques. The morphology depends on Pd:Ru ratio. The nanoflowers of Pd_5Ru catalyst are deposited on PEDOT surface in an alloy form. Cyclic voltammetry experiments indicate that Ru improves the catalytic activity of Pd for glycerol oxidation significantly. However, the oxidation of glycerol is not observed on Ru-PEDOT/C electrode. Amongst all compositions, Pd_5Ru nanoflowers on PEDOT exhibit the highest electrocatalytic activity and stability. Cyclic voltammetry and differential pulse voltammetry experiments are performed for the analysis of glycerol. Pd_5Ru-PEDOT/C electrode is highly sensitive towards glycerol detection with sensitivity of 99.8 μA cm"−"2 μM"−"1 and low detection limit of 0.1 μM. Thus, electrochemically deposited nanoflowers Pd_5Ru on PEDOT are efficient catalysts for direct glycerol oxidation as well as for analysis in alkaline media.
[en] We describe the differential cell design and the experimental (optical and electronic) setup for the differential front photopyroelectric technique, whose theory has been developed in the first part of this paper (Ivanov et al 2008 J. Phys. D: Appl. Phys. 41 085106). We will show first how the direct (non-differential) front photopyroelectric theory described in our previous paper reproduces well the experimental results. The usefulness of the differential technique is demonstrated by means of experimental measurements of the thermal effusivity in binary ethanol-water and glycerol-water mixtures, based on a theoretical methodology that simplifies the measurement procedure and diminishes the experimental uncertainty.
[en] In the original publication of the article, the Figures 6, 7, and 8 are in disagreement with their figure captions. Moreover, in the result and discussion section text the Fig 6 is called as Fig S2 (vibrational spectroscopy in the infrared region section).
[en] Under nitrogen starvation, Ustilago maydis forms lipid droplets (LDs). Although the dynamics of these organelles are known in the literature, the identity of the lipases implicated in their degradation is unknown. We determined lipase activity and identified the intracellular lipases expressed during growth under nitrogen starvation and YPD media by zymograms. The results showed that cytosolic extracts exhibited higher lipase activity when cells were grown in YPD. Under nitrogen starvation, lipase activity was not detected after 24 h of culture, resulting in lipid accumulation in LDs. This suggests that these lipases could be implicated in LD degradation. In the zymogram, two bands, one of 25 and the other of 37 kDa, presented lipase activity. The YPD extracts showed lipase activity in olive and almond oils, which contain triacylglycerols with mono and polyunsaturated fatty acids. This is the first report about U. maydis cytosolic lipases involved in LD degradation.
[es]En ausencia de nitrógeno, Ustilago maydis forma cuerpos lipídicos (LDs). Aunque se conoce la dinámica de estos organelos, se desconoce la identidad de las lipasas implicadas en su degradación. En este estudio se determinó la actividad de lipasa, y se identificaron las lipasas intracelulares expresadas durante el crecimiento sin nitrógeno y en YPD mediante zimogramas. Los extractos citosólicos de células en YPD exhibieron mayor actividad de lipasa. En medio sin nitrógeno no se detectó actividad de lipasa después de 24 h de cultivo, presentándose acumulación de lípidos en los LDs. Esto sugiere que estas lipasas podrían implicarse en la degradación de los LDs. En el zimograma bandas de 25 y 37 kDa, presentaron actividad de lipasa. Los extractos de células cultivadas en YPD hidrolizaron triacilgliceroles compuestos de ácidos grasos mono y poliinsaturados. Este es el primer reporte sobre lipasas citosólicas de U. maydis implicadas en la degradación de LDs.
[en] In the study the glycerin displacement method was used for determination of diffusible hydrogen content in deposited metal. Specimens were welded in the air and in the water with covered rutile electrodes. The first part of the specimens was made immediately after opening the package of the electrodes. The electrodes were then stored in opened packages in laboratory conditions that allowed for contact with the air for three years. After that time, the second part of the samples was made. The results of the measurements of the diffusible hydrogen amount in deposited metal ranged from 32.61 to 39.95 ml/100 g for specimens welded in the air and from 51.50 to 61.34 ml/100 g for specimens made in the water. The statistical analyses were performed in a Statistical software package using the ANOVA module (one-way analysis of variance) with an assumed significance level α = 0.05. The assumption of normality was verified by the Shapiro-Wilk test. The homogeneity of variance was verified by the Levene test. In the next step, post-hoc analyzes were made. The aim was to determine which averages are significantly different. Scheffe, Tukey, NIR Fisher, Newman-Keuls and Duncan tests were used. Possible changes in the diffusible hydrogen content in deposited metal resulting from storage time of electrodes (3 years) were verified by Student’s t-test. All of the statistical analysis shows that the storage time of the electrodes has no significant influence on the diffusible hydrogen content in deposited metal regardless of the welding environment.
[es]El método de desplazamiento de la glicerina se utilizó para determinar el contenido de hidrógeno difundido en el metal depositado. Las muestras se soldaron en aire y en agua con electrodos recubiertos de rutilo. En la primera parte, las se soldaron inmediatamente después de abrir el paquete con los electrodos. Posteriormente, los electrodos se almacenaron en paquetes abiertos en el ambiente de laboratorio durante 3 años. Pasado este tiempo, se realizó la segunda parte de las muestras. Los resultados de las mediciones de la cantidad de hidrógeno difundido en el metal depositado varió de 32,61 a 39,95 ml/100 g para muestras soldadas al aire y de 51,50 a 61,34 ml/100 g para muestras soldadas en agua. Los análisis estadísticos se realizaron utilizando el software Statistica, módulo ANOVA (análisis de varianza de una vía) con un supuesto nivel de validez α=0,05. La normalidad fue verificada por el ensayo Shapiro-Wilk. La homogeneidad de la varianza se verificó mediante el ensayo Levene. En la etapa siguiente, se realizaron análisis post-hoc. El objetivo fue determinar si los promedios son significativamente diferentes. Se utilizaron los ensayos Scheffe, Tukey, NIR Fisher, Newman-Keuls y Duncan. Los posibles cambios en el contenido de hidrógeno difundido en el metal depositado, resultante del tiempo de almacenamiento de los electrodos, se determinaron mediante el ensayo “t” de Student. Los resultados del análisis estadístico muestran que el tiempo de almacenamiento de los electrodos no tiene una influencia significativa en el contenido de hidrógeno difundido en el metal depositado, independientemente del sistema de apantallamiento utilizado en la soldadura.