Original reaction of p-nitrobenzyl chloride with aldehydes using tetrakis(dimethylamino)ethylene (TDAE)

A series of disubstituted diarylethanols was prepared in moderate to good yields by reaction of p-nitrobenzyl chloride (1) with various aromatic aldehydes (2-12) in presence of tetrakis(dimethylamino)ethylene (TDAE).     

Tagetnoic acid,a new lipoxygenase inhibitor peroxy fatty acid from Tagetes minuta growing in Saudi Arabia

Abstract

A new peroxy fatty acid, tagetnoic acid (5) [4-((3S,6S)-6-((3E,8E)-octadeca-3,8-dien-1-yl)-3,6-dihydro-1,2-dioxin-3-yl)butanoic acid] and four known metabolites: ecliptal (5-formyl-α-terthiophene) (1), 5-(4-hydroxybut-1-ynyl)-2,2′-bithiophene (2), 22,23-dihydrospinasterone (3), and stigmasterol (4) were separated from the n-hexane fraction of the aerial parts of Tagetes minuta L. (Asteraceae). Their chemical structures were verified using IR, UV, 2D and 1D NMR, and HRMS. Compounds 3–5 displayed potent lipoxygenase inhibitory potential with IC₅₀s 2.26, 1.83, and 1.17?μM, respectively compared to indomethacin (IC₅₀ 0.89?μM). Moreover, molecular docking study revealed that the potent activity of 5 is due to H-bonding and hydrophobic interaction. The results of this study suggested that Tagetes minuta dietary consumption would be useful for the individuals at risk of acute and chronic inflammatory disorders.     

Hydration characteristic on lime-silica fume pastes

The hydration of two calcium hydroxide— silica fume mixtures was studied at 25°C, these are Mix I and Mix II with molar lime/silica ratios of 1 and 1.7, respectively. The free lime, free silica and chemically combined water contents were determined at various time of hydration from which the molar CaO/SiO₂ ratios of the formed calcium silicate hydrate, C?S?H, were calculated. The results indicated that hydration takes place in six steps where C?S?H (I) is formed at early stages of hydration, for Mix I, While for Mix II formation of C?S?H (I) and C?S?H (II) were detected by X-ray diffraction analysis and differential thermal analysis.     

Insights on the Inhibitory Power of Flavonoids on Tyrosinase Activity: A Survey from 2016 to 2021

Tyrosinase is a multifunctional copper-containing oxidase enzyme that initiates melanin synthesis in humans. Excessive accumulation of melanin pigments or the overexpression of tyrosinase may result in skin-related disorders such as aging spots, wrinkles, melasma, freckles, lentigo, ephelides, nevus, browning and melanoma. Nature expresses itself through the plants as a source of phytochemicals with diverse biological properties. Among these bioactive compounds, flavonoids represent a huge natural class with different categories such as flavones, flavonols, isoflavones, flavan-3-ols, flavanones and chalcones that display antioxidant and tyrosinase inhibitor activities with a diversity of mechanistic approaches. In this review, we explore the role of novel or known flavonoids isolated from different plant species and their participation as tyrosinase inhibitors reported in the last five years from 2016 to 2021. We also discuss the mechanistic approaches through the different studies carried out on these compounds, including in vitro, in vivo and in silico computational research. Information was obtained from Google Scholar, PubMed, and Science Direct. We hope that the updated comprehensive data presented in this review will help researchers to develop new safe, efficacious, and effective drug or skin care products for the prevention of and/or protection against skin-aging disorders.     

Thermoelectric Phenomena in Gallium Monosulphide Single Crystals

Measurements of thermoelectric power of GaS single crystals grown by melt growth technique, were performed in the range of 150 K to 500 K. Investigations of GaS compound have revealed that it has interesting properties. Many physical parameters were determined such as carriers mobilities, effective masses of free charge carriers, diffusion coefficient and diffusion length as well as the relaxation time. Also the thermoelectric power behaviour showed the p-type nature of GaS crystals.     

Quantitative Analysis of Abamectin,Albendazole, Levamisole HCl and Closantel in Q-DRENCH Oral Suspension Using a Stability-Indicating HPLC-DAD Method

Combination therapy of many anthelmintic drugs has been used to achieve fast animal curing. Q-DRENCH is an oral suspension, containing four different active drugs against GIT worms in sheep, commonly used in Australia and New Zeeland. The anti-parasitic drugs are Albendazole (ALB), Levamisole HCl (LEV), Abamectin (ABA), and Closantel (CLO). The main purpose of this study is to present a new simultaneous stability-indicting HPLC-DAD method for the analysis of the four drugs. The recommended liquid system was 1 mL of Triethylamine/L water, adjusting the pH to 3.5 by glacial acetic acid: acetonitrile solvent (20:80, v/v). Isocratic elusion achieved the desired results of separation at a 2 mL/min flow rate using Zorbax C-18 as a stationary phase. Detection was performed at 210 nm. The linearity ranges were 15.15 to 93.75 μg/mL for ALB, 25 to 150 μg/mL for LEV, 30 to 150 μg/mL for ABA, and 11.7 to 140.63 μg/mL for CLO. Moreover, the final greenness score was 0.62 using the AGREE tool, which reflects the eco-friendly nature. Moreover, the four drugs were determined successfully in the presence of their stressful degradation products. This work presents the first chromatographic method for simultaneous analysis for Q-DRENCH oral suspension drugs in the presence of their stressful degradation products.     

Crystallization and Thermoelectric Power of Tl2Te3 Single Crystals

Thermoelectric power (TEP) of Tl₂Te₃ was measured in the temperature range from 150 to 480 K. The crystal was found to have a p-type conductivity throughout the whole range of temperature. The effective masses of holes and electrons were determined at room temperature and found to be m = 1.1 × 10⁻³⁴ kg and m = 1.72 × 10⁻³⁵ kg, respectively. Also at the same temperature the mobility μ_p was found to be 1737.8 cm²/V.s and μ_n was 3962.2 cm²/V.s. The hole and electron diffusion coefficients were obtained as 44.84 cm²/s, and 102.23 cm²/s. The relaxation times for holes and electrons were calculated and yielded the values τ_p = 1.19 × 10¹² s and τ_n = 4.25 × 10¹³ s, respectively.     

Photoelectric studies of gallium monosulfide single crystals

Photoconductivity (PC) studies were carried out on GaS single crystals prepared from melt by directional solidification. We studied the effect of light intensity, applied voltage on both the PC and the lifetime of carriers. The V-I characteristics and the absorption spectra were checked for different sample thickness. The present investigation was extended to study the spectral distribution of the photocurrent for GaS. It was found that the photocurrent curves are practically independent of the bias voltage. The energy gap for GaS was found to be 2.5 eV.     

Electrical properties of pure and Li2O-doped CuO/Fe2O3 system precalcined at different temperatures

The electrical properties of pure and Li₂O-doped CuO/Fe₂O₃ solids were investigated. Pure and variously doped solids were subjected to thermal treatment at 1073–1273 K and the amount of dopant was varied between 0.84 to 3.36 mol%. The effect of precalcination temperature and amount of Li₂O added on the electrical conductivity σ, activation energy E_a and dielectric constant * were studied. The variation of ′ and ″ as a function of frequency for pure and variously doped solids precalcined at different temperatures was also investigated. The results obtained were discussed.     

Dielectric Properties of Hyperbranched Polyesteramide with Long Alkyl Chain End Groups

Summary: Hyperbranched polyesteramides were prepared using phethalic anhydride (Ph An) or maleic anhydride (M An) as an A₂ monomer and diethanol amine (DEA) as B′B₂ monomer. Bulk condensation technique was used to synthesize polymers with both OH and modified polymers with long alkyl chain end groups. The prepared polymers were characterized using ¹H-NMR, FTIR and TGA. Solution viscosity for hyperbranched polyester amide with hydroxyl end groups was measured as well. Dielectric and electric properties of the modified samples were investigated over a range of frequency and temperatures. No relaxation peak is noticed in the dielectric spectrum ε(ν) at various temperatures. The illustration of the imaginary part of the electric modulus M″ versus frequency shows a peak which is shifted towards higher frequency in increasing temperature.