Hydrodynamic water tunnel for characterization of hydrokinetic microturbines designs

Clean Technologies and Environmental Policy - The enormous inroads made by renewable energy in recent years have been the key to the development of new technologies designed to obtain energy from a...     

Assessment of Tractable Cysteines for Covalent Targeting by Screening Covalent Fragments

Targeted covalent inhibition and the use of irreversible chemical probes are important strategies in chemical biology and drug discovery. To date, the availability and reactivity of cysteine residues amenable for covalent targeting have been evaluated by proteomic and computational tools. Herein, we present a toolbox of fragments containing a 3,5-bis(trifluoromethyl)phenyl core that was equipped with chemically diverse electrophilic warheads showing a range of reactivities. We characterized the library members for their reactivity, aqueous stability and specificity for nucleophilic amino acids. By screening this library against a set of enzymes amenable for covalent inhibition, we showed that this approach experimentally characterized the accessibility and reactivity of targeted cysteines. Interesting covalent fragment hits were obtained for all investigated cysteine-containing enzymes.     

Synthesis,characterization and kinetic study of the Sr2FeMoO6-δ double perovskite: New findings on the calcination of one of its precursors

Sr₂FeMoO_6-δ double perovskites are widely-recognized due to several important factors: high electronic conductivity and electrocatalytic activity, structural stability under reducing atmospheres, high transition temperature, enormous magnetoresistance, reasonable tolerance to carbon formation, and their desirable capacity to avoid sulfur poisoning. One of the methods most commonly-used to synthetize these perovskites is solid-state reaction. The precursor phases usually associated with this method are the oxides SrMoO₄ and SrFeO_3-δ when Fe2O₃, SrCO₃, and MoO₃ are the initial reagents used. Morphological, XRD (Rietveld), and thermogravimetry (calcination and reduction) analyses are steps or routes towards achieving the final result. While recent studies suggest that the temperature of calcination is always 900 °C and that reduction occurs at 1200 °C, they fail to explain why this occurs. This article demonstrates, according to the results of thermogravimetric analysis (TGA), that as calcination advances weight loss increases until a temperature of 850 °C is reached. In addition, it stresses the importance of the ball milling technique at ambient temperature to prevent sublimation of the MoO₃ compound at 700 °C in the later steps of synthesis, such as calcination and reduction. According to the kinetic study, the values of activation energy (Ea) and reaction order (n) were 130.47 kJ/mol and 1 respectively.     

Global and Latin American scientific production related to pneumococcal vaccines

Scientometrics - The most effective way to fight against diseases caused by Streptococcus pneumoniae is prevention through vaccination. The present study analyzed global and Latin American...     

Copper removal from a cyanidation liquor by electrowinning using batch and continuous flow cells.

ABSTRACT

The cyanidation process is used for the recovery of gold and silver from their ores. However, during cyanidation, some of the copper minerals present are also dissolved, resulting in the presence of copper impurities in the form of cuprocyanide complexes. A high copper content in solution decreases the recovery of precious metals, mainly due to zinc passivation during gold/silver cementation. The objective of this work is to study the effect on copper electrowinning of the cyanide/copper molar ratio, the potential applied to the electrolytic cell, the temperature and circulation rate of the solution, and the use of synthetic solutions with physicochemical characteristics similar to those of an industrial solution. The experiments were carried out in electrolytic reactors using different regimes (i.e. batch and continuous). The results obtained indicate that an applied potential of 4?V at temperatures above of 25°C, significantly increases the amount of copper removed, while high cyanide concentrations resulted in low levels of copper removal. Furthermore, the intensification of the agitation of the solution increases the amount of copper removed due to enhanced mass transfer conditions. Copper removal in the continuous reactor was of approximately 50%. Metallic copper was deposited on the cathode and copper oxide and copper hydroxide on the anode.     

A taxonomy for similarity metrics between Markov decision processes

Machine Learning - Although the notion of task similarity is potentially interesting in a wide range of areas such as curriculum learning or automated planning, it has mostly been tied to transfer...     

Thermochemical hydrogen production using manganese cobalt spinels as redox materials

Mn and Co spinels (Mn_3-xCo_xO₄) were thermally reduced and subsequently oxidized showing successful hydrogen production from water splitting by a three-step thermochemical cycle involving sodium hydroxide (NaOH). The spinel materials overcome the main limitation of the Mn₂O₃/MnO redox cycle, reducing the required temperatures from 1300–1400 °C to 850–1050 °C. Additionally, the reduction process takes place through a single step reaction, avoiding the formation of intermediate species that makes much more complex the chemistry of the Mn₂O₃ redox cycle. On the other hand, the subsequent reaction with NaOH allows a hydrogen production of 52.5 cm³ STP/g_material·cycle, which is comparable to the obtained with other spinel-oxide cycles at similar temperature. The cyclability and stability of the hydrogen production with these materials after operation of several cycles have been assessed in a high temperature tubular furnace.     

Use of basic color terms by red–green dichromats. II. Models

Abstract: In our companion article (Color Res Appl 2013) we compared the use of Basic Color Terms (BCTs) by normal trichromats, protanopes, and deuteranopes in a mapping (which colors are instances of X?) and best exemplar (which is the best X?) tasks. In this article, we describe and compare two alternative models of the mechanisms underlying the use of Basic Color Terms (BCTs) by red–green dichromats and we focus on how well they fit the empirical data described in the companion article. Model A assumes that BCT use is based on the activity of the yellow–blue and lightness channels, whereas Model B also assumes that there is some degree of input from the red–green channel. Model B was more accurate than Model A in predicting: (1) The frequency of use of BCTs. (2) The distribution of correct responses for many BCTs in both tasks. (3) The distribution of correct responses and kind of errors for many BCTs. (4) The locations of the centroids for both tasks. We conclude that activity in a“residual” red–green channel influences the use of BCTs by R‐G dichromats, as well as the activity of the yellow–blue and lightness channels. The asymmetry of errors for some pairs of BCTs and the differences between primary and derived BCTs are also discussed. This article, in combination with its complementary one (Color Res Appl 2013), provides a comprehensive and detailed overview of how R‐G dichromats use BCTs to categorize surface colors and can integrate and explain some of the results and conclusions obtained in earlier research. © 2013 Wiley Periodicals, Inc. Col Res Appl, 39, 372–386, 2014