Topic
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.
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TL;DR: In this paper, chitosan films were prepared using 3 chitoshan molecular weights and 4 organic acid solvents without plasticizer, and the results showed that tensile strength and elongation increased with the molecular weight.
Abstract: Chitosan films were prepared using 3 chitosan molecular weights and 4 organic acid solvents without plasticizer. Tensile strength (TS) and elongation (E) ranged from 6.7 to 150.2 MPa, and from 4.1 to 117.8%, respectively. Water vapor permeability (WVP) and oxygen permeability (OP) ranged from 0.3 to 0.7 ng-m/m2-s-Pa and OP from 0.4 to 5.8 × 10 −8 cc/m2-day-atm, respectively. TS increased with chitosan molecular weight. Acetic acid resulted in the toughest films followed by malic, lactic, and citric acid, respectively. Films prepared with citric acid had the highest E values. WVP was not influenced significantly by the molecular weight of chitosan. OP of films prepared with malic acid was the lowest, followed by acetic, lactic, and citric acid.
317 citations
TL;DR: Change in the mitochondrial pH gradient provides a sensitive mechanism for regulating renal substrate metabolism, and is mediated by alteration in the pH gradient across the inner mitochondrial membrane.
Abstract: The rate of intracellular metabolism of citrate plays a major role in determining the amount of citrate excreted in the urine. Fractional excretion of citrate can be increased either by increasing intracellular citrate synthesis from precursors or by inhibiting mitochondrial citrate metabolism. Increased excretion secondary to increased synthesis of citrate occurs when citric acid cycle precursors such as malate or succinate are infused. Increased excretion resulting from inhibition of citrate metabolism occurs when malonate, maleate, or fluorocitrate is administered. Systemic acid-base changes cause striking changes in citrate clearance and metabolism. Recent evidence suggests that the effects of acid-base changes are mediated by alteration in the pH gradient across the inner mitochondrial membrane. Metabolic alkalosis causes cytoplasmic pH and bicarbonate to increase, resulting in a decrease in the mitochondrial pH gradient. This change inhibits the tricarboxylate carrier, slowing entry of citrate into the mitochondrial matrix compartment. The level of citrate in the cytoplasm increases, tubular and peritubular citrate uptake are reduced, and citrate clearance increases. Opposite changes occur in acidosis. Change in the mitochondrial pH gradient provides a sensitive mechanism for regulating renal substrate metabolism.
315 citations
TL;DR: The degree of Al tolerance by transformed plants in hydroponic solutions and in naturally acid soil corresponded with their patterns of organic acid exudation and supports the concept that enhancing organic acid synthesis in plants may be an effective strategy to cope with soil acidity and Al toxicity.
Abstract: Al toxicity is a severe impediment to production of many crops in acid soil. Toxicity can be reduced through lime application to raise soil pH, however this amendment does not remedy subsoil acidity, and liming may not always be practical or cost-effective. Addition of organic acids to plant nutrient solutions alleviates phytotoxic Al effects, presumably by chelating Al and rendering it less toxic. In an effort to increase organic acid secretion and thereby enhance Al tolerance in alfalfa (Medicago sativa), we produced transgenic plants using nodule-enhanced forms of malate dehydrogenase and phosphoenolpyruvate carboxylase cDNAs under the control of the constitutive cauliflower mosaic virus 35S promoter. We report that a 1.6-fold increase in malate dehydrogenase enzyme specific activity in root tips of selected transgenic alfalfa led to a 4.2-fold increase in root concentration as well as a 7.1-fold increase in root exudation of citrate, oxalate, malate, succinate, and acetate compared with untransformed control alfalfa plants. Overexpression of phosphoenolpyruvate carboxylase enzyme specific activity in transgenic alfalfa did not result in increased root exudation of organic acids. The degree of Al tolerance by transformed plants in hydroponic solutions and in naturally acid soil corresponded with their patterns of organic acid exudation and supports the concept that enhancing organic acid synthesis in plants may be an effective strategy to cope with soil acidity and Al toxicity.
308 citations
TL;DR: The results show that addition of citric acid decreased the adsorption of both lead and cadmium, and increased the abundance of F(H2O) + F(NaCl), indicating thatcitric acid treatment could transform cadmiam into more transportable forms.
302 citations
TL;DR: The thermophilic and alkaliphilic Bacillus sp. JB-99 was isolated from sugarcane molasses and was cultured in 250 ml Erlenmeyer flasks containing 50 ml of synthetic medium consisting of (g/l): citric acid; 10.0, NaNO 3 ; 10.
298 citations