(E)-Alkyl ortho-hydroxycinnamates cyclize to coumarins at elevated temperatures of 140-250 °C. We find that the use of tri-n-butylphosphane (20 mol %) as a nucleophilic organocatalyst in MeOH solution allows cyclization to take place under much milder conditions (60-70 °C). Several coumarins were prepared, starting from ortho-hydroxyarylaldehydes, by Wittig reaction with Ph(3)P=CHCO(2)Me to (E)...

This paper presents a control scheme for the Modular Multilevel Converter (MMC) to drive a variablespeed AC machine, especially focusing on improving dynamic performance. Theoretically, the energy balance in the MMC cell capacitors is prone to be unstable at start-up and at low frequency operations. Additionally, the MMC topology essentially requires advanced control strategies to balance energ...

Daidzein and genistein are two major components of soy isoflavones. They exist abundantly in plants and possess multiple bioactivities. In contrast, ortho-hydroxydaidzein (OHD) and ortho-hydroxygenistein (OHG), including 6-hydroxydaidzein (6-OHD), 8-hydroxydaidzein (8-OHD), 3'-hydroxydaidzein (3'-OHD), 6-hydroxygenistein (6-OHG), 8-hydroxygenistein (8-OHG), and 3'-hydroxygenistein (3'-OHG), are...

This study was carried out to obtain optimum operation conditions for X-ray machines. We investigated some factors affecting on quality assurance of conventional Siemen X-ray machine, inone of Mansoura Hospitals such as reproducibility of dose output, time and applied high voltage, Kilo-voltage accuracy, mA accuracy, time accuracy, and linearity. We measured these factors using Non-Invasive kil...

a simple extremely fast and efficient approach for the synthesis of substituted indazole ingood to excellent yield catalyzed by using silica sulfuric acid (ssa) in dmso solvent at roomtemperature. this is solid state reaction have been attracting the synthetic organic chemist asthey provided enhance reaction rates, less environmental pollution, greater selectivity, cleanerproducts and manipulat...

a new dimeric orthopalladated complex was synthesized via reaction of 2,3-dimethoxy benzaldehyde oxime with palladium chloride and lithium chloride in methanol as solvent and sodium acetate as base at room temperature. the catalytic activity of this dimeric [pd{c6h2(-ch=noh)-(ome)2-2,3}(µ-cl)]2 complex as an efficient, air, and moisture tolerant catalyst was investigated in mizoroki–heck cross ...

Recently, studies on the construction of 3D terrain modeling and location accuracy evaluation using UAV have been conducted, but application to coastal areas lacking image matching points has not made in detail yet. In topography survey UAV, ortho-images DSM (Digital Surface Model) data were constructed through imaging ground control point (GCP) surveying ground. case ortho-images, VRS was used...

BACKGROUND The present study was conducted to evaluate the effect of different topical agents utilized for prevention of enamel decalcification around orthodontic brackets bonded to bleached and non-bleached enamel. METHODS Human maxillary premolars (n = 120) were divided into two equal groups. Teeth in group I were left without bleaching while those in group II were bleached with Vivastyle g...

Reaction of ortho-carborane with anhydrous AlCl3 in chloroform results a mixture 9-chloro, 9,12-dichloro, and 8,9,12-trichloro derivatives 9,12-dichloro-ortho-carborane being the main product. Molecular crystal structure was determined by single X-ray diffraction. The 9,12-Cl2-1,2-C2B10H10 appeared to be nearly isostructural 9,12-dibromo-ortho-carborane: packing is built layers which molecules ...

INTRODUCTION Tetrodotoxin (Figure 1) is a naturally occurring compound isolated from the liver and ovaries of puffer fish. Due to its potent toxicity as a selective blocker of voltage-gated Na ion channels and the high regard for puffer fish as a culinary delicacy, tetrodotoxin has become a molecule of general, as well as scientific, interest. Structural determination revealed a densely functio...