Kinetic,thermodynamic parameters and in vitro digestion of tannase from Aspergillus tamarii URM 7115

Tannase is an enzyme used in various industries and produced by a large number of microorganisms. The aim of this study was to evaluate tannase production to determine the biochemical, kinetic, and thermodynamic properties and to simulate tannase in vitro digestion. The tannase-producing fungal strain was isolated from “jamun” leaves and identified as Aspergillus tamarii. Temperature at 26°C for 67?h was the best combination for maximum tannase activity (6.35-fold; initial activity in Plackett–Burman design—15.53?U/mL and average final activity in Doehlert design—98.68?U/mL). The crude extract of tannase was optimally active at 40°C, pH 5.5 and 6.5. Moreover, tannase was stimulated by Na⁺, Ca²⁺, Mg²⁺, and Mn²⁺. The half-life at 40°C lasted 247.55?min. The free energy of Gibbs, enthalpy, and entropy, at 40°C, was 81.47, 16.85, and ?0.21?kJ/mol?·?K, respectively. After total digestion, 123.95% of the original activity was retained. Results suggested that tannase from A. tamarii URM 7115 is an enzyme of interest for industrial applications, such as gallic acid production, additive for feed industry, and for beverage manufacturing, due to its catalytic and thermodynamic properties.     

Effect of annealing on the permeation characteristics of gases of coextruded LLDPE films

The temperature dependence of both the permeability and diffusion coefficients of carbon dioxide, oxygen and nitrogen in annealed LLDPE films are studied. It is found that the values of the permeability coefficient through the annealed membranes are nearly four times larger than those through the non-annealed ones. The fact that annealing slightly diminishes the values of the diffusion coefficient leads to the conclusion that the rise in permeability detected in the films by effect of annealing should be attributed to an increase in solubility. The permeability characteristics of the films are interpreted in terms of the free volume theory.     

Chemical Composition Determination at the Bottom Region of a Recovery Boiler Furnace by Direct Minimization of Gibbs Free Energy

An optimization strategy has been applied to describe the chemical composition at the furnace bottom in the Kraft recovery boiler of a pulp production process. The concentrations of each involved chemical species were calculated through an optimization approach, minimizing the Gibbs free energy of the system. Various systems were proposed and tested, assuming different chemical species and phases number. Because serious initialization problems were found at this stage for some of the proposed systems, an optimization heuristic method (PSO) was used for the first approach to the problem. Once the appropriate phases number and chemical species in the system were determined, the initialization problems disappeared and the use of a deterministic optimization method (SQP) became viable. The proposed approach has shown to be satisfactory to reproduce industrial data and also data reported in the open scientific literature.     

A mixed longitudinal and cross-sectional model to forecast the journal impact factor in the field of Dentistry

Scientometrics - In order to estimate the impact factor value for a journal in Dentistry, two sets of variables were considered in this study: the first takes in the longitudinal behavior of the...     

Immunotherapy for Biliary Tract Cancer in the Era of Precision Medicine: Current Knowledge and Future Perspectives

Biliary tract cancers (BTC) represent a heterogeneous and aggressive group of tumors with dismal prognosis. For a long time, BTC has been considered an orphan disease with very limited therapeutic options. In recent years a better understanding of the complex molecular landscape of biology is rapidly changing the therapeutic armamentarium. However, while 40–50% of patients there are molecular drivers susceptible to target therapy, for the remaining population new therapeutic options represent an unsatisfied clinical need. The role of immunotherapy in the continuum of treatment of patients with BTC is still debated. Despite initial signs of antitumor-activity, single-agent immune checkpoint inhibitors (ICIs) demonstrated limited efficacy in an unselected population. Therefore, identifying the best partner to combine ICIs and predictive biomarkers represents a key challenge to optimize the efficacy of immunotherapy. This review provides a critical analysis of completed trials, with an eye on future perspectives and possible biomarkers of response.     

Ranking of departments and researchers within a university using two different databases: Web of Science versus Scopus

In this work, we compare the difference in the number of citations compiled with Scopus as opposed to the Web of Science (WoS) with the aim of analysing the agreement among the citation rankings generated by these databases. For this, we analysed the area of Health Sciences of the University of Navarra (Spain), composed of a total of 50 departments and 864 researchers. The total number of published works reflected in the WoS during the period 1999–2005 was 2299. For each work, the number of citations in both databases was recorded. The results indicate that the works received 14.7% more citations in Scopus than in WoS. In the departments, the difference was greater in the clinical ones than in the basic ones. In the case of the rankings of citations, it was found that both databases generate similar results. The Spearman and Kendall-Tau coefficients were higher than 0.9. It was concluded that the difference in the number of citations found did not correspond to the difference of coverage of WoS and Scopus.     

Tribological behaviour of C-alloyed transition metal dichalcogenides (TMD) coatings in different environments

W-S-C films were deposited by non-reactive sputtering from a carbon target incrusted with WS₂ pellets in the eroded zone. This process allows depositing coatings with a wide range of compositions, with a precise control of their carbon content. Before the deposition, a Ti interlayer was interposed between the film and the substrate to improve the final adhesion. The carbon content in W-S-C system was varied from 29 at.% to 70 at.%, which led to an hardness enhancement from 4 GPa up to 10 GPa where the maximum hardness was reached in films with a carbon content between 40 at.% and 50 at.%. The tribological behaviour of the coatings was evaluated by pin-on-disk testing, in environments with different humidity levels. Generally, the tribological performance of W-S-C coatings in environments with moderate to high humidity is better for coatings with high carbon content. Friction coefficients, as 0.05 or lower could be reached at low humidity ranges (<7%) to all compositions. However, for higher humidity values, friction coefficient increased up to 0.30 in the W-S-C film with low carbon content whereas it was kept approximately constant for the others compositions.     

The use of particle swarm optimization for dynamical analysis in chemical processes

Particle swarm optimization is employed here to evaluate the parametric regions where different dynamic phenomena (periodic oscillations, double-period oscillations, chaos) can be expected in dynamic models. The proposed algorithm comprises two fundamental steps: the rough evaluation of regions where the desired solutions can be found and solution refining. The refining step allows the search for unstable solutions that may coexist with the other stable attractors. No preliminary bifurcation analysis is required. Simulations performed for distinct dynamic models show that the proposed algorithm is indeed able to locate different dynamic phenomena in the parameter space and that the algorithm may be of help for those interested in increasing the speed of more traditional dynamic bifurcation analysis.     

Transport of gases and vapors in methacrylic copolymers of varying side chain length

The gas transport properties of copolymers of dodecyl methacrylate with ethyl methacrylate and hydroxypropyl methacrylate have been studied. The diffusion, solubility and permeability of oxygen, nitrogen, carbon dioxide, methane, ethane and ethylene have been measured in the temperature range 0-50 °C, and activation energies and heats of solution have been obtained. A comparison with the data available in the literature on acrylates and other methacrylates of varying aliphatic side chain length has been performed. The diffusion coefficient of gases increases with the side chain length in a way similar to that found for homologous acrylates. A representation of log(D) as a function of the inverse of the fractional free volume shows that all acrylates and methacrylates of lineal alkyl side chain fall on the same straight line.     

Oxygen transport through methacrylate-based hydrogels with potential biological capability

The permeability to oxygen of hydrogels prepared from copolymers of 2-hydroxymethyl methacrylate and p-methacryloxyl-oxyacetanilide have been studied by using an oxygen electrode in combination with a permeometer. The transmissibility Dk/L and the permeability Dk (where D, k and L are, respectively, the diffusion coefficient, the Henry constant and the thickness of the hydrogel) are measured by a combination of steady state and transitory state measurements. Both transport coefficients increase with the water content, which in turn depends on the copolymer composition. The values of these quantities tend toward a limiting value for water-saturated hydrogels. The ratio of the characteristic volume for diffusion of the oxygen molecule to the free volume of water per mole water is found to be in the vicinity of 0.10, and this value increases slightly as the fraction of the hydrophilic comonomer in the hydrogel increases. A detailed comparison of the biogels studied with six commercial contact lenses has also been performed.