Polymeric templating synthesis of anatase TiO₂ nanoparticles from low-cost inorganic titanium sources

A novel facile and cost-effective synthesis method for anatase TiO₂ nanoparticles has been developed by using poly-acrylic acid hydrogel as template at room temperature. The newly developed synthesis method avoids the use of hazardous reagents and/or hydrothermal steps, and enables production of highly active TiO₂ nanoparticles from low cost inorganic titanium sources. The synthesized TiO₂ nanoparticles have been studied in several applications including dye-sensitized solar cells as a photoanode as well as in organics degradation of methyl orange in aqueous media. Good photocatalytic performances were obtained in both applications

Individual performances relative to season bests in major track running championship races are distance-, position- and sex-dependent

Objectives. To compare season’s best times preceding major championships (SBprior) and times achieved in major championship flat track races. Material and methods. 2320 men’s and 2312 women’s finishing times over 100 m, 400 m, 800 m, 1500 m and 5000 m at the International Association of Athletics Federations (IAAF) World Championships and Olympic Games from 1999 to 2019, and their SBprior, were obtained via IAAF open-access website. Paired t-tests were used to compare major championship times and SBprior for groups across sex in each event. Repeated measures ANOVA was used to examine differences in the percentage of SBprior achieved in the major championship races (%SBprior) between groups and sexes. Results. Finishing time performances were generally slower than SBprior. The difference between SBprior and championship performances increased with distance run and across preliminary rounds and finals. Differences in %SBprior between sexes were found in non-medal finalists in the 800 m and 5000 m (p < 0.001, ES ≥ 0.72). Conclusions. 1500 m and 5000 m athletes competing at major championships should train and be physiologically prepared to sustain non-even paces and produce a fast endspurt to achieve an optimal performance

Constraining the primordial spectrum of metric perturbations from gravitino and moduli production

We consider the production of gravitinos and moduli fields from quantum vacuum fluctuations induced by the presence of scalar metric perturbations at the end of inflation. We obtain the corresponding occupation numbers, up to first order in perturbation theory, in terms of the power spectrum of the metric perturbations. We compute the limits imposed by nucleosynthesis on the spectral index $n_s$ for different models with constant $n_s$. The results show that, in certain cases, such limits can be as strong as $n_s<1.12$, which is more stringent than those coming from primordial black hole production.Comment: 16 pages, LaTeX, 5 figures. Corrected figures, new references included. Final version to appear in Phys. Rev.

Estudio de la idoneidad de un nuevo hormigón estructural fabricado con áridos ligeros reforzados con fibra de carbono sinterizados a partir de residuos

The suitability of three new lightweight aggregates containing carbon fiber residues (CAs) as components in structural lightweight concrete has been studied. Prismatic concrete specimens were prepared using these CAs as a coarse fraction. Additional specimens of normal-weight aggregate, commercial lightweight aggregate and mortar were prepared for comparison. The CA-concrete samples (CACs) have yielded compressive strength values between 35 and 55 MPa as well as low density and thermal conductivity results. Furthermore, the CACs have displayed the highest ratios of mechanical strength over density and the thermal conductivity, which means that there is a better balance between their mechanical and physical properties than in the other samples studied. These results indicate that the new CAs could have great potential for use in structural lightweight concrete, also complying with the principles of the Circular Economy.Este estudio pretende comprobar la idoneidad de unos novedosos áridos ligeros sinterizados con residuos de fibra de carbono (CAs) en la fabricación de hormigón ligero estructural. Se prepararon probetas prismáticas de hormigón, utilizando estos CAs como fracción gruesa, comparándose a su vez con probetas fabricadas con un árido convencional, un árido ligero comercial y mortero. Las muestras de hormigón con los áridos CA (en adelante CAC) han dado lugar a valores de resistencia a compresión entre 35 y 55 MPa, así como a resultados bajos de densidad y conductividad térmica, mostrando además las ratios más altas al relacionar estos tres parámetros. Esto indicaría por tanto un mejor equilibrio entre las propiedades mecánicas y físicas que los obtenidos en las otras muestras estudiadas. Estos resultados apuntan a que los nuevos CAs podrían tener un gran potencial para su uso en hormigón ligero estructural, cumpliendo además los principios de la Economía Circular

Co-digestion of mixed sewage sludge and fruit and vegetables wastes effect of different mixtures on biogas yield

Disposal of fruit and vegetable wastes (FVWs) in landfill site cause serious environmental issues such as contamination of soil, air and ground water. These wastes contain large quantities of biodegradable organic fractions, with high moisture that facilitates their biological treatment. One of the best alternatives to landfill disposal of these wastes is the anaerobic digestion. Therefore, it is one of the most widespread stabilization processes of the sludge in municipal wastewater treatment plants (WWTP). Introduction of FVW in WWTP and co-digestion with mixed sludge (MS) could enhance biogas production and plant economic feasibility. A lab-scale experiment for the anaerobic co-digestion of FVW and municipal mixed sludge under mesophilic condition and 20 days hydraulic retention time is investigated. Initially the digester was fed with mixed sludge (MS) from wastewater treatment plants with an average organic loading rate (OLR) of 0.63 (g L–1 d–1). The co-digestion of mixed sludge and FVW was performed at various organic loading ratios (OLRs), between 0.63 and 5.5 (g L–1 d–1). The experimental specific biogas and methane productions are 0.656 L g–1 and 0.340 L g–1 respectively. Alkalinity and pH remains relatively constant regardless the introduction of different proportions of FVW in the mixture. Co-digestion, compared with the digestion of MS as single substrate, improves the biogas and methane production.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Evaluación de efectos difusionales sobre la cinética de hidrólisis de lecitina de soja con fosfolipasa A2

Soluble or immobilized A2 phospholipase liberates one mole of fatty acid of the C-2 position in soybean lecithin phospholipids to product lysolecithins. When using the enzyme in its immobilized form the enzymatic activity decreases due to substrate and product transport phenomenon. By comparison of the kinetic parameters of the hydrolysis reaction catalized by A2 phospholipase immobilized on alumina or on DEAE-Sephadex against those of the soluble enzyme, for soybean lecithin hydrolysis reaction, the diffusive effects were evaluated. The decrease of the reaction rate was quantified in presence of diffusive effects and the effectiveness factors were calculated. The Michaelis-Menten kinetic parameters were determined: KM = 8,2.10-2 mol·l-1 and 5,36.10-2 mol·l-1 and Vmax = 7,7.10-5 mol·l-1 .min-1 and 9,5.10-5 mol·l-1 ·min-1 for the enzyme immobilized on alumina and on DEAE-Sephadex, respectively. The effectiveness factors were 0,277 for alumina and 0,376 for DEAE-Sephadex.La Fosfolipasa A2, soluble o inmovilizada, libera un mol de ácido graso de la posición C-2 de los fosfolípidos de la lecitina de soja para producir lisolecitinas. Cuando se utiliza la enzima en su forma inmovilizada, la actividad enzimática decrece debido al fenómeno de transporte de sustrato y de producto. Se evaluaron los efectos de difusión comparando los parámetros cinéticos de la reacción de hidrólisis de lecitina de soja catalizada por fosfolipasa A2 inmovilizada sobre alúmina o sobre DEAE-Sephadex, frente a los de enzima soluble. La disminución de la velocidad de reacción fue cuantificada en presencia de efectos difusionales y se calcularon los factores de eficiencia. Se determinaron los parámetros de Michaelis-Menten: KM = 8,2.10-2 mol·l-1 and 5,36.10-2 mol·l-1 y Vmax = 7,7.10-5 mol·l-1 .min-1 y 9,5.10-5 mol·l-1 ·min-1 para la enzima inmovilizada sobre alúmina y sobre DEAE-Sephadex, respectivamente. El factor de eficiencia fue 0.277 para alúmina y 0.376 para DEAE-Sephadex

Estudio cinético de la reacción de hidrólisis de lecitina de soja pura en polvo con fosfolipasa A2 inmovilizada

Immobilized A2 phospholipase enzyme promotes the hydrolytic reaction of pure powder soybean lecithin releasing a mole of fatty acid from C-2 position. The main purpose of this paper was to determine the kinetic parameters of this reaction when the enzyme was adsorbed on alumina or DEAE-sephadex. The best conditions for the reaction were: temperature: 45-48ºC, Ca ions concentration: 6mM, pH: 8,65. Tested conditions for substrate concentration were: 6,3; 12,7; 19 and 25 mM working in a batch type reactor and with the immobilized enzyme. The incubating time did not change the enzymatic activity. The hydrolytic activity of alumina or DEAE-sephadex adsorbed A2 phospholipase enzyme was lower than of the soluble enzyme because the intrinsic properties are modified by immobilization. For substrate concentrations ranging between 6 and 19 mM first order kinetic velocity constants were k = 9, 88. 10-2 min-1 and k = 1,766. 10-1 min-1 for alumina and DEAEsephadex respectively. For the same supports but at higher substrate concentration (25mM) the zero order kinetic velocity constants were k= 1,62. 10-3 mol.l-1min-1 (alumina) and k = 3,58. 10-3 mol.l-1 min-1 (DEAE-sephadex).La enzima fosfolipasa A2 inmovilizada promueve la reacci&oacute;n hidrol&iacute;tica de lecitina de soja pura en polvo liberando un mol de &aacute;cido graso de la posici&oacute;n C-2. El principal prop&oacute;sito de este trabajo fue determinar los par&aacute;metros cin&eacute;ticos de la reacci&oacute;n cuando la enzima fue adsorbida sobre al&uacute;mina o sobre DEAE-sephadex. Las mejores condiciones para la reacci&oacute;n son: temperatura 45-48&ordm;C: concentraci&oacute;n de iones Ca 6 mM y pH 8,65. Las concentraciones de sustrato ensayadas fueron 6,3; 12,7; 19 y 25 mM trabajando en un reactor tipo batch y con la enzima inmovilizada. El tiempo de incubaci&oacute;n no modific&oacute; la actividad enzim&aacute;tica. La actividad hidrol&iacute;tica de fosfolipasa A2 adsorbida sobre al&uacute;mina o sobre sephadex fue menor que la de la enzima soluble porque las propiedades intr&iacute;nsecas de la enzima se modificaron con la inmovilizaci&oacute;n. Para concentraciones de sustrato entre 6 y 19 mM las constantes de velocidad para cin&eacute;tica de 1er orden fueron k = 9,88.10-2 min-1 para enzima inmovilizada sobre al&uacute;mina y k = 1,766.10-1 min-1 para enzima inmovilizada sobre DEAE-sephadex. Para los mismos soportes,&nbsp; pero a mayores concentraciones de sustrato (25mM) las constantes de velocidad para cin&eacute;tica de orden cero fueron k = 1,62.10-3 mol.l-1min-1 (al&uacute;mina) y k = 3,58. 10-3 mol.l-1 min-1 (DEAE-sephadex)

Purificación de lecitina de soja. 1-Selección de equipamiento y determinación de las condiciones operativas. 2-Obtención de diagrama de equilibrio

In this work we describe the choice of the best operating conditions to produce pure powder soybean lecithin, extracting with acetone, in a bench scale. The equipment was designed in order to obtain adequate impeller and turbine systems response because there is significant viscosity variations between batches, and the extraction process was difficult. By operating in these conditions, we have obtained the equilibrium values for the phospholipids/oil/acetone mixture. The results showed that there are a phospholipids/oil interaction and this might be by solute absorption or because the solute is soluble in the solid and it is no reparting by equal between the equilibrium liquid and solid phases.En el presente trabajo se describe la selección de las condiciones operativas óptimas para la purificación de lecitina de soja, utilizando acetona y operando en discontinuo. El equipo se diseñó teniendo en cuenta que se producía una gran variación de la viscosidad que dificultaba la extracción, por lo que se debió prestar especial atención al diseño del sistema impulsor y del sistema agitador. Operando bajo estas condiciones se obtuvieron los valores de equilibrio para la mezcla fosfolípidos/aceite/acetona. Los resultados evidencian interacción entre los fosfolípidos y el aceite, bien porque habría absorción preferente de soluto o bien porque el soluto es soluble en el sólido y no se distribuye por igual entre las fases líquidas y sólidas en el equilibrio

The equivalence theorem and the production of gravitinos after inflation

We study the high-energy equivalence between helicity 1/2 gravitinos and goldstinos in order to calculate the production of gravitinos in time-dependent scalar and gravitational backgrounds. We derive this equivalence for equations of motion, paying attention to some subtleties, mainly due to external sources, that are not present in the standard proofs. We also propose the Landau gauge as a simplifying alternative to the usual gauge choices, both for practical calculations and in the equivalence theorem proof.Comment: 13 pp. 2 figures. Final and shorter version to appear in Phys. Rev. D. References and minor errata correcte