Bond graph model of an induction machine with hysteresis nonlinearities

An induction machine is one of the most convenient devices for conversion of electrical energy to mechanical rotational energy. Induction machine is a typical member of a multi-domain, nonlinear, high-order dynamic system. To reduce its complexity, the mathematical models used for designing their control have several assumptions built into them. The most striking of these assumptions is that of linear magnetics. Bond graph is a convenient tool for modelling nonlinear elements. This paper proposes the use of the bond graph methodology to develop a model of an induction machine that includes the nonlinearities due to magnetics.     

Structural Features and HER activity of Cadmium Phosphohalides

We have carried out a combined experimental and theoretical investigation of the structures and properties of a family of cadmium phosphochlorides with varying Cl/Cd and P/Cd ratios, Cd₂P₃Cl, Cd₄P₂Cl₃, Cd₃PCl_3, and Cd₇P₄Cl₆. Their optical band gaps are in the visible region and the values are sensitive to the Cl/Cd and P/Cd ratios, leading to an increase and decrease, respectively. First‐principles calculations were used to understand the bonding and electronic structures. All phosphochlorides except Cd₂P₃Cl possess direct band gaps. The calculated dielectric constants and Born effective charges illustrate the bonding, hybridization, and ionic character in these compounds. The band positions indicate the thermodynamic feasibility to perform water splitting. All systems can be used in the hydrogen evolution reaction (HER), where Cd₇P₄Cl₆ has the highest activity and Cd₃PCl₃ the lowest. The apparent quantum yield is highest in Cd₇P₄Cl₆ (20.1 %) even without the assistance of a co‐catalyst. The HER activity can be understood on the basis of photoelectrochemical measurements.     

In silico fight against novel coronavirus by finding chromone derivatives as inhibitor of coronavirus main proteases enzyme

Structural Chemistry - Novel coronavirus, 2019-nCoV is a danger to the world and is spreading rapidly. Very little structural information about 2019-nCoV make this situation more difficult for drug...     

Ubiquitous Amyloids

The common view of amyloids and prion proteins is that they are associated with many currently incurable diseases and present a great danger to an organism. This danger comes from the fact that not only prion proteins, but also the infectious form(s) of amyloids, as it has been shown recently, are able to transmit the disease. On the other hand, organisms take advantage of the strength and durability of specific forms of amyloids. Such forms do not spread any disease. Also, in nanotechnology there is a constantly growing need to employ amyloid fibrils in many industrial applications. With increasing knowledge about amyloids and prion proteins we are aware that the amyloidal state is inherent to any protein, making the problem of amyloid formation a central one in aging-related diseases. However, the “good” amyloids can be beneficial and even necessary for our health. Furthermore, because of their mechanical properties, the amyloids are of great interest to engineers.     

Fluorescent and Chromogenic Receptor Bearing Amine and Hydroxyl Functionality for Iron (III) Detection in Aqueous Solution

The noncyclic 2,2′-[ethane-1,2-diylbis (iminomethanediyl)]diphenol (4) fluorescent receptor bearing two amine and hydroxyl groups have been designed and investigated for their binding properties towards various cations. The fluorescent spectral measurements revealed that receptor 4 is a selective fluorescent sensor for Fe³⁺ ions but not for metal ions such as Cr³⁺, Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Hg²⁺, Pb²⁺ and Bi³⁺. The binding ability was confirmed with spectroscopic methods and density functional theory calculation (DFT). This straightforward and cost effective receptor provides rapid detection of Fe³⁺ ions at concentrations as low as 2.5 μM and expected to be useful to design efficient chemically and biological sensor.     

One-pot synthesis of 2-aminothiazoles in PEG-400

<正>A facile one-pot synthesis of 2-aminothiazoles has been carried in PEG-400 as a greener medium at room temperature.This method avoids the use of lachrymatric a-bromoketones as well as the volatile,toxic organic solvents.     

Pharmaceutical grade sodium [99mTc] pertechnetate from low specific activity 99Mo using an automated 99Mo/99mTc-TCM-autosolex generator

Performance study of a computer controlled automated closed cyclic module for the separation and recovery of ^99mTc from low specific activity (n, γ) ⁹⁹Mo using methyl ethyl ketone (MEK) solvent extraction technique named ⁹⁹Mo/^99mTc-TCM-AUTOSOLEX (Technetium automated solvent extraction) Generator is described. The entire system is automated and controlled by a user-friendly PC based graphical user interface that actually supervises process via an embedded system based electronic controller. The average yield of separation of ^99mTc was above 85 % and ⁹⁹Mo breakthrough in ^99mTc pertechnetate was <0.002 %. The sodium pertechnetate obtained was a clear solution having pH 6–7, Radiochemical (RC). Purity >99 %, MEK content <0.1 % (v/v), Al and Mo content <10 µg/ml. R. C. Purity of ^99mTc-radiopharmaceuticals studied was not less than 96 %. Bio-Quality control studies confirm that sodium pertechnetate obtained was sterile and pyrogen free. Imaging studies in animals and humans with limited radiopharmaceuticals show that the quality of ^99mTc-pertechenate obtained in the present module was good enough to do clinical study.     

Thermal and spectral properties of alkali metal complexes of 2-hydroxy-1,4-naphthoquinone

Thermal and spectral studies of reactions between 2-hydroxy-1,4-naphthoquinone (lawsone) and sodium metal (Lw-1, Lw-1A, Lw-1B), CH₃COONa (Lw-2), NaOH (Lw-3), KOH (Lw-4), K₂CO₃ (Lw-5), Tris buffer (Lw-6), ammonia (Lw-7) are studied. Red solids of Lw-1 to Lw-7, Lw-1A, and Lw-1B were isolated and are characterized by elemental analysis, FT-IR, ¹H NMR and UV–Visible spectroscopy. FT-IR spectra of Lw-1A and Lw-1B show, ν _OH of adsorbed as well as coordinated water molecules between 3,600–3,100 cm^?1 and decrease in ν _C=O frequency of lawsone ligand. The benzenoid ring protons C(5)H, C(8)H, C(6)H and C(7)H in Lw-1A and Lw-1B show upfield shift in ¹H NMR spectra. Hypsochromic shift and bathochromic shift is observed to π–π* transition band (~329 nm) and charge transfer band (~455 nm), respectively in UV–Visible spectra of all compounds. Pyrolytic decomposition of all compounds is studied by nonisothermal TG studies in air. Step I in all compounds leads to loss of adsorbed water molecules. Decomposition of lawsone anion in all compounds occurs in two or more steps. Thermodynamically Lw-1 to Lw-7, Lw-1A and Lw-1B are different compounds and their decomposition mechanisms are varied. The respective metal oxide residue viz. (Na₂O or K₂O) obtained after complete decomposition of Lw-1 to Lw-5, Lw-1A, and Lw-1B, is analyzed by powder X-ray diffraction. The adsorbed as well as coordinated water molecules are revealed by DTA and DSC studies as endothermic peak at ~100 °C. Decomposition mechanisms for lawsone anion are proposed based on LC–MS, GC–MS, and TG studies. Thermal and spectral studies reveal the coordination of lawsone ligand in its naphthosemiquinone form with alkali metal ions.     

Study on One‐pot Biginelli‐like Synthesis of Pyrazolo[3,4‐d]pyrimidines in Bronsted Acidic Ionic Liquid Under Sonication and its Mechanism

Pyrazolo[3,4‐d]pyrimidine derivatives were synthesized using ionic liquid, 1‐butylimidazolium tetrafluoroborate, under ultrasound irradiation at ambient condition without any added catalyst. Mechanistic pathway based on the catalytic role of ionic liquid has been proposed. This method offers the advantages of simple procedure, milder reaction condition, easier workup and improved yield over the conventional method. The ionic liquid could be recycled at least three times with marked retention in its activity.