Proportional concentration phenomena on the sphere

In this paper we establish concentration phenomena for subspaces with arbitrary dimension. Namely, we display conditions under which the Haar measure on the sphere concentrates on a neighborhood of the intersection of the sphere with a subspace ofR ⁿ of a given dimension. We display applications to a problem of projections of points on the sphere, and to the duality of entropy numbers conjecture. Research was partially supported by the Israel Science Foundation.     

Electrochemical Pseudocapacitors Based on Ternary Nanocomposite of Conductive Polymer/Graphene/Metal Oxide: An Introduction and Review to it in Recent Studies

This review gives an overview of the synthesis, surface and electrochemical investigations over ternary nanocomposite of conductive polymers in the development of new supercapacitors. They utilize both Faradaic and non‐Faradaic procedures to store charge, leading to higher specific capacitance and energy density, higher cell voltage, longer life cycle and moderated power density. Owing to a unique combination of features such as superb electrical conductivity, corrosion resistance in aqueous electrolytes, highly modifiable nanostructures, long cycle life and the large theoretical specific‐surface area, the use of ternary nanocomposites as a supercapacitor electrode material has become the focus of a significant amount of current scientific researches in the field of energy storage devices. In these nanocomposites, graphene not only can be utilized to provide a substrate for growing nanostructured polymers in a polymer‐carbon nanocomposite structure in order to overcome the insulating nature of conductive polymers at dedoped states, but also is capable of providing a platform for the decoration of metal oxide nanoparticles to avoid their agglomeration. In this regard, synthesis, characterization and performance of different ternary nanocomposites of conductive polymer/graphene/metal oxide are discussed in detail. These remarkable results demonstrate the exciting commercial potential for high performance, environmentally friendly and low‐cost electrical energy storage devices based on ternary nanocomposite of conductive polymer/graphene/metal oxide.     

Synthesis of 14-Aryl-14H-7-thiadibenzo[a,j]anthracene

Abstract

Preparation methods of dibenzoxanthene derivatives are surveyed alongside the synthesis of some of the titled compounds, which are the sulfur analogues of dibenzoxanthenes. Our new procedure for the conversion of phenols to thiophenols was used to prove the structure of such sulfur analogues.     

Inhibitive assessment of 1-(7-methyl-5-morpholin-4-yl-thiazolo[4,5-d]pyrimidin-2-yl)-hydrazine as a corrosion inhibitor for mild steel in sulfuric acid solution

In this study, the inhibitive effect of synthesized 1-(7-methyl-5-morpholin-4-yl-thiazolo[4,5-d]pyrimidin-2-yl)-hydrazine (MMTPH) as a new corrosion inhibitor for mild steel in 0.5 M sulfuric acid medium is investigated employing potentiodynamic polarization, electrochemical impedance spectroscopy and linear polarization resistance techniques. The results show MMTPH reduces anodic dissolution, retards the hydrogen evolution reaction and its adsorption follows Langmuir’s adsorption isotherm. Any increase in temperature will in turn increase corrosion current densities; however, the presence of MMTPH hinders the rate. In solutions with inhibitor concentration of 200 ppm, temperature elevations as great as 30° (25–55 °C) result in a drop of about 45 % in inhibition efficiency (99–55 %). Thermodynamic adsorption parameters show that the MMTPH is absorbed by a spontaneous exothermic process and the adsorption mechanism is physical. Quantum chemical method shows that the MMTPH molecules can be directly adsorbed at the steel surface on the basis of donor–acceptor interactions between π-electrons of pyrimidine, N atoms of hydrazine and vacant d-orbitals of iron atoms.     

Synthesis of arylidenepyruvic amide derivatives via Ugi-four component condensation

Arylidenepyruvic acids (APAs) have been successfully employed in an Ugi-four component condensation reaction which yielded polyfunctional amides. Condensation of various APAs, aldehydes, amines, and isocyanides at room temperature in 96% ethanol as a green solvent proceeded in good yields. The extension of the reaction to diamines, formaldehyde, and isocyanides to form more complex molecules is also reported. These novel products may have potential in various pharmaceutical applications.     

Synthesis of 9-substituted tetrahydrodiazepinopurines: studies toward the total synthesis of asmarines

A methodology for the preparation of asmarine analogues has been developed. The asmarines are cytotoxic marine alkaloids with a unique tetrahydro[1,4]diazepino[1,2,3-g,h]purine (THDAP) structure. Three cyclization methods were applied for the preparation of the 9,9-disubstituted 10-hydroxy-THDAP system, namely, aminomercurization, iodocyclization, and acid-catalyzed cyclization. The DMPM group of the NOH functionality and cyanoethyl group of the N-9 atom were found to be the most suitable protecting groups. The structures of all compounds were mainly determined from NMR measurements including (15)N chemical shifts obtained from (15)NH HMBC spectra. The end products are at least about 1 order of magnitude less active than the natural product asmarine B.     

Duality of metric entropy in Euclidean space

Let K be a convex body in a Euclidean space, K° its polar body and D the Euclidean unit ball. We prove that the covering numbers N(K,tD) and N(D,tK°) are comparable in the appropriate sense, uniformly over symmetric convex bodies K, over t>0 and over the dimension of the space. In particular this verifies the duality conjecture for entropy numbers of linear operators, posed by Pietsch in 1972, in the central case when either the domain or the range of the operator is a Hilbert space. To cite this article: S. Artstein et al., C. R. Acad. Sci. Paris, Ser. I 337 (2003).     

Analysis of trans-Resveratrol in Iranian Grape Cultivars by LC

In this study, trans-resveratrol levels were determined in 147 Iranian grape cultivars using a modified extraction and gradient HPLC procedure with photodiode array detection. It was found that 41 out of 147 cultivars contained significant levels of trans-resveratrol. The detected amounts ranged from 0.98 to 6.25 mg kg⁻¹ fresh weight with a mean value of 3.59 (white grapes) and 3.08 mg kg⁻¹ (red grapes), respectively.

     

Mechanistic study of fenoprofen photoisomerization to pure (S)-fenoprofen: a DFT study

Structural Chemistry - This work provides a comprehensive DFT study on the conversion mechanism and photoisomerization of the effective and commonly used nonsteroidal anti-inflammatory medicine...