Citric acid

About: Citric acid is a research topic. Over the lifetime, 17745 publications have been published within this topic receiving 277125 citations. The topic is also known as: citrate & H3cit.

Etch Rates and Selectivities of Citric Acid/Hydrogen Peroxide on GaAs , Al0.3Ga0.7As , In0.2Ga0.8As , In0.53Ga0.47As , In0.52Al0.48As , and InP

Abstract: Etching studies involving citric acid/hydrogen peroxide (C 6 H 8 O 7 :H 2 O 2 ) at volume ratios from 0.5: 1 to 50: 1 were found to provide good selective etching of various III-V semiconductor materials grown on GaAs and InP substrates using molecular beam epitaxy. Both selective and uniform (nonselective) etching regions were found between these material systems by choosing different concentration volume ratios of citric acid/hydrogen peroxide (χC 6 H 8 O 7 :1H 2 O 2 )

Aluminum Activates a Citrate-Permeable Anion Channel in the Aluminum-Sensitive Zone of the Maize Root Apex. A Comparison Between an Aluminum- Sensitive and an Aluminum-Resistant Cultivar

Abstract: In search for the cellular and molecular basis for differences in aluminum (Al) resistance between maize ( Zea mays ) cultivars we applied the patch-clamp technique to protoplasts isolated from the apical root cortex of two maize cultivars differing in Al resistance. Measurements were performed on protoplasts from two apical root zones: The 1- to 2-mm zone (DTZ), described as most Al-sensitive, and the main elongation zone (3–5 mm), the site of Al-induced inhibition of cell elongation. Al stimulated citrate and malate efflux from intact root apices, revealing cultivar differences. In the elongation zone, anion channels were not observed in the absence and presence of Al. Preincubation of intact roots with 90 μmAl for 1 h induced a citrate- and malate-permeable, large conductance anion channel in 80% of the DTZ protoplasts from the resistant cultivar, but only 30% from the sensitive cultivar. When Al was applied to the protoplasts in the whole-cell configuration, anion currents were elicited within 10 min in the resistant cultivar only. La 3+ was not able to replace or counteract with Al 3+ in the activation of this channel. In the presence of the anion-channel blockers, niflumic acid and 4, 4′-dinitrostilbene-2, 2′disulfonic acid, anion currents as well as exudation rates were strongly inhibited. Application of cycloheximide did not affect the Al response, suggesting that the channel is activated through post-translational modifications. We propose that the Al-activated large anion channel described here contributes to enhanced genotypical Al resistance by facilitating the exudation of organic acid anions from the DTZ of the maize root apex.

Liquid aerosol formulation of an electronic smoking article

Abstract: A liquid aerosol formulation for an electronic smoking article includes an aerosol former, optionally water, nicotine, and an acid. The acid can include one or more of pyruvic acid, formic acid, oxalic acid, glycolic acid, acetic acid, isovaleric acid, valeric acid, propionic acid, octanoic acid, lactic acid, levulinic acid, sorbic acid, malic acid, tartaric acid, succinic acid, citric acid, benzoic acid, oleic acid, aconitic acid, butyric acid, cinnamic acid, decanoic acid, 3,7-diemthyl-6-octenoic acid, 1-glutamic acid, heptanoic acid, hexanoic acid, 3-hexenoic acid, trans-2-hexenoic acid, isobutyric acid, lauric acid, 2-methylbutyric acid, 2-methylvaleric acid, myristic acid, nonanoic acid, palmitic acid, 4-pentenoic acid, phenylacetic acid, 3-phenylpropionic acid, hydrochloric acid, phosphoric acid and sulfuric acid.

Overview of citric acid production from Aspergillus niger

Abstract: Citric acid has high economic potential owing to its numerous applications. It is mostly produced by microbial fermentation using Aspergillus niger. In view of surges in demand and growing markets, there is always a need for the discovery and development of better production techniques and solutions to improve production yields and the efficiency of product recovery. To support the enormous scale of production, it is necessary and important for the production process to be environmentally friendly by utilizing readily available and inexpensive agro-industrial waste products, while maintaining high production yields. This article reviews the biochemistry of citric acid formation, choices of citric-acid producing microorganisms and raw materials, fermentation strategies, the effects of various fermentation conditions, citric acid recovery options and the numerous applications of citric acid, based on information drawn from the literature over the past 10 years.