The Molecular-Kinetic Approach to Hydrolysis of Boron Hydrides for Hydrogen Production

Kinetics and Catalysis - In this study, Langmuir–Hinshelwood and Michaelis–Menten kinetic models are applied to describe the kinetic behaviour of the Co–B catalyst in the...     

Aqua­di­chloro­(di‐2‐pyridyl­di­azene)copper(II) monohydrate

The crystal structure of the mononuclear title complex, [CuCl₂(C₁₀H₈N₄)(H₂O)]·H₂O, shows an s‐cis/E/s‐trans‐configured di‐2‐pyridyl­diazene ligand, with the square‐pyramidal Cu^II ion coordinated to one pyridyl and one diazene N atom together with two Cl atoms and one aqua ligand. The crystal packing involves both hydrogen‐bonding and π–π interactions. The solvent water mol­ecule links three monomers to one another through hydrogen‐bonding interactions in which two monomers are linked via chloro ligands and the third via the aqua ligand. Face‐to‐face and weak slipped π–π interactions also occur between di‐2‐pyridyl­diazene moieties, and these interactions are responsible for the interchain packing.     

Extending external rays throughout the Julia sets of rational maps

For polynomial maps in the complex plane, the notion of external rays plays an important role in determining the structure of and the dynamics on the Julia set. In this paper we consider an extension of these rays in the case of rational maps of the form Fλ(z) = z ⁿ + λ/z ⁿ where n > 1. As in the case of polynomials, there is an immediate basin of ∞, so we have similar external rays. We show how to extend these rays throughout the Julia set in three specific examples. Our extended rays are simple closed curves in the Riemann sphere that meet the Julia set in a Cantor set of points and also pass through countably many Fatou components. Unlike the external rays, these extended rays cross infinitely many other extended rays in a manner that helps determine the topology of the Julia set.     

An alternative globalization strategy for unconstrained optimization

We propose a new globalization strategy that can be used in unconstrained optimization algorithms to support rapid convergence from remote starting points. Our approach is based on using multiple points at each iteration to build a sequence of representative models of the objective function. Using the new information gathered from those multiple points, a local step is gradually improved by updating its direction as well as its length. We give a global convergence result and also provide the parallel implementation details accompanied with a numerical study. Our numerical study shows that the proposed algorithm is a promising alternative as a globalization strategy.     

Devolatilization non-isothermal kinetic analysis of agricultural stalks and application of TG-FT/IR analysis

Devolatilization behavior of several types of agricultural stalks (sunflower, rice, corn, and wheat) was studied using thermogravimetric system (TG) under nitrogen atmosphere at different heating rates (10, 15, and 20 °C min^-1). Coats&Redfern, Horowitz&Metzger, and Arrhenius non-isothermal kinetic models were applied to calculate the devolatilization kinetic parameters and the devolatilization rate equations have been established. In addition, the kinetic compensation effect (KCE) has also been used to correlate pre-exponential factor (k _o) with activation energy (E _a) and an existence of the KCE is accepted. TG-FT/IR analyses were applied of the different stalks and FT/IR stack plot used to analyze the devolatilization gas products (CO₂, CH₄, HCOOH, CH₃OH). Infrared vibrational frequencies, micro structure and crystallinity of stalks were investigated by Fourier transform infrared spectroscopy (FT/IR), scanning electron microscope (SEM), and X-ray diffraction analysis (XRD), respectively.     

On the automorphisms of generalized algebraic geometry codes

Designs, Codes and Cryptography - We consider the class of generalized algebraic geometry codes (GAG codes) formed by two collections of places, with places of the same degree in each collection....     

Process for the conversion of highly caustic spent sodium borohydride fuel

The presence of caustic soda in the spent sodium borohydride (NaBH₄) fuel in high concentrations creates environmental problems associated with the transportation and the disposal of the fuel, orits recycling into NaBH₄. It is clear that the high level of caustic soda in the spent fuel requires efficient and proper formulation of its industrial recycling applications. The present study regards the conversion process of the caustic soda present in high concentrations in spent NaBH₄ fuels. Properties of the caustic used in NaBH₄ fuel is characterized using a comprehensive technique. A specific application is presented here, which includes the treatment of the spent fuel solution with anhydrous borax (Na₂B₄O₇) at 90?°C for 3?h followed by calcination after the crystallization, resulting in the conversion of this highly caustic spent NaBH₄ fuel into sodium metaborate (NaBO₂), which is an environmentally friendlier and an economically valuable material.     

The Synthesis of Sodium Sulfide Pentahydrate,Na2S·5H2O,Through a Solid-Gas Reaction of Sulfidizing Gas Mixture with Sodium Carbonate,Na2CO3

In this study, the sulfidization of Na₂CO₃ was investigated by using a solid-gas reaction under a sulfidizing gas mixture, which consisted of COS, CS₂, and S₂ gases.

Sodium sulfide pentahydrate, Na₂S·5H₂O, was prepared from sodium carbonate, Na₂CO₃, via a sulfidizing gas mixture by a solid-gas reaction under the cooling of a nitrogen atmosphere. The observed phase was found to be the pentahydrated form of sodium sulfide. This crystalline form was determined by X-ray powder diffraction (XRD) technique. Since sodium sulfide is strongly hygroscopic, the pentahydrated crystalline form was observed in XRD measurements for all repeated experiments. The crystal unit cell parameters of the synthesized product were in excellent agreement with values given in the JCPDS card number 18-1249. The sodium sulfide pentahydrate has an orthorhombic crystal structure with the unit cell parameters of a = 6.475, b = 12.55, C = 8.655 Å, space group, Cmcm and Z = 4.