Effects of EDTA and low molecular weight organic acids on soil solution properties of a heavy metal polluted soil.

PubMed

Wu, L H; Luo, Y M; Christie, P; Wong, M H

2003-02-01

A pot experiment was conducted to study the effects of EDTA and low molecular weight organic acids (LMWOA) on the pH, total organic carbon (TOC) and heavy metals in the soil solution in the rhizosphere of Brassica juncea grown in a paddy soil contaminated with Cu, Zn, Pb and Cd. The results show that EDTA and LMWOA have no effect on the soil solution pH. EDTA addition significantly increased the TOC concentrations in the soil solution. The TOC concentrations in treatments with EDTA were significantly higher than those in treatments with LMWOA. Adding 3 mmol kg(-1) EDTA to the soil markedly increased the total concentrations of Cu, Zn, Pb and Cd in the soil solution. Compared to EDTA, LMWOA had a very small effect on the metal concentrations. Total concentrations in the soil solution followed the sequence: EDTA > citric acid (CA) approximately oxalic acid (OA) approximately malic acid (MA) for Cu and Pb; EDTA > MA > CA approximately OA for Zn; and EDTA > MA > CA > OA for Cd. The labile concentrations of Cu, Zn, Pb and Cd showed similar trends to the total concentrations.

21 CFR 184.1033 - Citric acid.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Citric acid. 184.1033 Section 184.1033 Food and....1033 Citric acid. (a) Citric acid (C6H8O7, CAS Reg. No. 77-92-9) is the compound 2-hydroxy-1,2,3... crystals or a white powder and may be anhydrous or contain one mole of water per mole of citric acid...

Citric Acid Passivation of Stainless Steel

NASA Technical Reports Server (NTRS)

Yasensky, David; Reali, John; Larson, Chris; Carl, Chad

2009-01-01

Passivation is a process for cleaning and providing corrosion protection for stainless steel. Currently, on Kennedy Space Center (KSC), only parts passivated with nitric acid are acceptable for use. KSC disposes of approximately 125gal of concentrated nitric acid per year, and receives many parts from vendors who must also dispose of used nitric acid. Unfortunately, nitric acid presents health and environmental hazards. As a result, several recent industry studies have examined citric acid as an alternative. Implementing a citric acid-based passivation procedure would improve the health and environmental safety aspects of passivation process. However although there is a lack of published studies that conclusively prove citric acid is a technically sound passivation agent. In 2007, NASA's KSC Materials Advisory Working Group requested the evaluation of citric acid in place of nitric acid for passivation of parts at KSC. United Space Alliance Materials & Processes engineers have developed a three-phase test plan to evaluate citric acid as an alternative to nitric acid on three stainless steels commonly used at KSC: UNS S30400, S41000, and S17400. Phases 1 and 2 will produce an optimized citric acid treatment based on results from atmospheric exposure at NASA's Beach Corrosion Facility. Phase 3 will compare the optimized solution(s) with nitric acid treatments. If the results indicate that citric acid passivates as well or better than nitric acid, NASA intends to approve this method for parts used at the Kennedy Space Center.

21 CFR 582.1033 - Citric acid.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Citric acid. 582.1033 Section 582.1033 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1033 Citric acid. (a) Product. Citric acid. (b) Conditions of use. This substance is generally...

21 CFR 582.1033 - Citric acid.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Citric acid. 582.1033 Section 582.1033 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1033 Citric acid. (a) Product. Citric acid. (b) Conditions of use. This substance is generally...

21 CFR 582.1033 - Citric acid.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Citric acid. 582.1033 Section 582.1033 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1033 Citric acid. (a) Product. Citric acid. (b) Conditions of use. This substance is generally...

21 CFR 582.1033 - Citric acid.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Citric acid. 582.1033 Section 582.1033 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1033 Citric acid. (a) Product. Citric acid. (b) Conditions of use. This substance is generally...

21 CFR 582.6033 - Citric acid.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Citric acid. 582.6033 Section 582.6033 Food and..., FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Sequestrants 2 § 582.6033 Citric acid. (a) Product. Citric acid. 2 For the purpose of this subpart, no attempt has been made to...

21 CFR 582.6033 - Citric acid.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Citric acid. 582.6033 Section 582.6033 Food and..., FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Sequestrants 2 § 582.6033 Citric acid. (a) Product. Citric acid. 2 For the purpose of this subpart, no attempt has been made to...

21 CFR 582.6033 - Citric acid.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Citric acid. 582.6033 Section 582.6033 Food and..., FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Sequestrants 2 § 582.6033 Citric acid. (a) Product. Citric acid. 2 For the purpose of this subpart, no attempt has been made to...

21 CFR 582.6033 - Citric acid.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Citric acid. 582.6033 Section 582.6033 Food and..., FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Sequestrants 2 § 582.6033 Citric acid. (a) Product. Citric acid. 2 For the purpose of this subpart, no attempt has been made to...

21 CFR 582.6033 - Citric acid.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Citric acid. 582.6033 Section 582.6033 Food and..., FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Sequestrants 2 § 582.6033 Citric acid. (a) Product. Citric acid. 2 For the purpose of this subpart, no attempt has been made to...

Citraturic response to oral citric acid load

NASA Technical Reports Server (NTRS)

Sakhaee, K.; Alpern, R.; Poindexter, J.; Pak, C. Y.

1992-01-01

It is possible that some orally administered citrate may appear in urine by escaping oxidation in vivo. To determine whether this mechanism contributes to the citraturic response to potassium citrate, we measured serum and urinary citrate for 4 hours after a single oral load of citric acid (40 mEq.) in 6 normal subjects. Since citric acid does not alter acid-base balance, the effect of absorbed citrate could be isolated from that of alkali load. Serum citrate concentration increased significantly (p less than 0.05) 30 minutes after a single oral dose of citric acid and remained significantly elevated for 3 hours after citric acid load. Commensurate with this change, urinary citrate excretion peaked at 2 hours and gradually decreased during the next 2 hours after citric acid load. In contrast, serum and urinary citrate remained unaltered following the control load (no drug). Differences of the citratemic and citraturic effects between phases were significant (p less than 0.05) at 2 and 3 hours. Urinary pH, carbon dioxide pressure, bicarbonate, total carbon dioxide and ammonium did not change at any time after citric acid load, and did not differ between the 2 phases. No significant difference was noted in serum electrolytes, arterialized venous pH and carbon dioxide pressure at any time after citric acid load and between the 2 phases. Thus, the citraturic and citratemic effects of oral citric acid are largely accountable by provision of absorbed citrate, which has escaped in vivo degradation.

Removal of heavy metals from contaminated soil by electrodialytic remediation enhanced with organic acids.

PubMed

Merdoud, Ouarda; Cameselle, Claudio; Boulakradeche, Mohamed Oualid; Akretche, Djamal Eddine

2016-11-09

The soil from an industrial area in Algeria was contaminated with Cr (8370 mg kg -1 ), Ni (1135 mg kg -1 ) and zinc (1200 mg kg -1 ). The electrodialytic remediation of this soil was studied using citric acid and EDTA as facilitating agents. 0.1 M citric acid or EDTA was added directly to the soil before it was introduced in an electrodialytic cell in an attempt to enhance the heavy metal solubility in the interstitial fluid. The more acidic pH in the soil when citric acid was used as the facilitating agent was not enough to mobilize and remove the metals from the soil. Only 7.2% of Ni and 6.7% of Zn were removed from the soil in the test with citric acid. The best results were found with EDTA, which was able to solubilize and complex Zn and Ni forming negatively charged complexes that were transported and accumulated in the anolyte. Complete removal was observed for Ni and Zn in the electrodialytic treatment with EDTA. Minor amounts of Cr were removed with both EDTA and citric acid.

Citric acid production from extract of Jerusalem artichoke tubers by the genetically engineered yeast Yarrowia lipolytica strain 30 and purification of citric acid.

PubMed

Wang, Ling-Fei; Wang, Zhi-Peng; Liu, Xiao-Yan; Chi, Zhen-Ming

2013-11-01

In this study, citric acid production from extract of Jerusalem artichoke tubers by the genetically engineered yeast Yarrowia lipolytica strain 30 was investigated. After the compositions of the extract of Jerusalem artichoke tubers for citric acid production were optimized, the results showed that natural components of extract of Jerusalem artichoke tubers without addition of any other components were suitable for citric acid production by the yeast strain. During 10 L fermentation using the extract containing 84.3 g L(-1) total sugars, 68.3 g L(-1) citric acid was produced and the yield of citric acid was 0.91 g g(-1) within 336 h. At the end of the fermentation, 9.2 g L(-1) of residual total sugar and 2.1 g L(-1) of reducing sugar were left in the fermented medium. At the same time, citric acid in the supernatant of the culture was purified. It was found that 67.2 % of the citric acid in the supernatant of the culture was recovered and purity of citric acid in the crystal was 96 %.

Evaluation of the smear layer removal and erosive capacity of EDTA, boric acid, citric acid and desy clean solutions: an in vitro study.

PubMed

Turk, Tugba; Kaval, Mehmet Emin; Şen, Bilge Hakan

2015-09-03

The purpose of this study was to investigate the smear layer removal and erosive capacity of various irrigation solutions with sequential use of NaOCl on instrumented root canal walls. The root canals of single-rooted teeth were instrumented with ProTaper rotary instrument. Then, the teeth were randomly divided into five experimental groups. The root canals were irrigated with one of the following solutions (5 mL/1 min): 5% EDTA, 5% boric acid (BA), a mixture of BA and CA, 2.5% citric acid (CA) and 5% Desy Clean. After irrigating with 2.5% NaOCl and distilled water, the roots were split into two halves and each half was prepared for SEM examination. Representative photographs were taken from each third at x500 and x1000 magnifications. Double blind scoring was performed by two calibrated observers for smear layer and erosion. The scores were statistically analyzed using Kruskal-Wallis, Dunn's post hoc and Spearman's correlation tests (p = 0.05). There were statistically significant differences among the solutions by means of smear layer and erosion (p < 0.05). While 2.5% CA solution was the most effective solution in removal of smear layer, it was also the most erosive solution (p < 0.05). 5% Desy Clean removed smear layer effectively and caused less erosion. There was a negative, but statistically significant correlation between presence of smear layer and erosion (r = -0.684; p < 0.0001). Desy Clean can be a promising agent as an irrigation solution with optimal smear layer removal capacity and less erosive effects.

21 CFR 173.280 - Solvent extraction process for citric acid.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Solvent extraction process for citric acid. 173... Solvent extraction process for citric acid. A solvent extraction process for recovery of citric acid from conventional Aspergillus niger fermentation liquor may be safely used to produce food-grade citric acid in...

21 CFR 173.280 - Solvent extraction process for citric acid.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Solvent extraction process for citric acid. 173... Solvent extraction process for citric acid. A solvent extraction process for recovery of citric acid from conventional Aspergillus niger fermentation liquor may be safely used to produce food-grade citric acid in...

21 CFR 173.280 - Solvent extraction process for citric acid.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Solvent extraction process for citric acid. 173... Solvent extraction process for citric acid. A solvent extraction process for recovery of citric acid from conventional Aspergillus niger fermentation liquor may be safely used to produce food-grade citric acid in...

21 CFR 173.280 - Solvent extraction process for citric acid.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Solvent extraction process for citric acid. 173.280... extraction process for citric acid. A solvent extraction process for recovery of citric acid from conventional Aspergillus niger fermentation liquor may be safely used to produce food-grade citric acid in...

Submerged citric acid fermentation on orange peel autohydrolysate.

PubMed

Rivas, Beatriz; Torrado, Ana; Torre, Paolo; Converti, Attilio; Domínguez, José Manuel

2008-04-09

The citrus-processing industry generates in the Mediterranean area huge amounts of orange peel as a byproduct from the industrial extraction of citrus juices. To reduce its environmental impact as well as to provide an extra profit, this residue was investigated in this study as an alternative substrate for the fermentative production of citric acid. Orange peel contained 16.9% soluble sugars, 9.21% cellulose, 10.5% hemicellulose, and 42.5% pectin as the most important components. To get solutions rich in soluble and starchy sugars to be used as a carbon source for citric acid fermentation, this raw material was submitted to autohydrolysis, a process that does not make use of any acidic catalyst. Liquors obtained by this process under optimum conditions (temperature of 130 degrees C and a liquid/solid ratio of 8.0 g/g) contained 38.2 g/L free sugars (8.3 g/L sucrose, 13.7 g/L glucose, and 16.2 g/L fructose) and significant amounts of metals, particularly Mg, Ca, Zn, and K. Without additional nutrients, these liquors were employed for citric acid production by Aspergillus niger CECT 2090 (ATCC 9142, NRRL 599). Addition of calcium carbonate enhanced citric acid production because it prevented progressive acidification of the medium. Moreover, the influence of methanol addition on citric acid formation was investigated. Under the best conditions (40 mL of methanol/kg of medium), an effective conversion of sugars into citric acid was ensured (maximum citric acid concentration of 9.2 g/L, volumetric productivity of 0.128 g/(L.h), and yield of product on consumed sugars of 0.53 g/g), hence demonstrating the potential of orange peel wastes as an alternative raw material for citric acid fermentation.

Phytoextraction of contaminated urban soils by Panicum virgatum L. enhanced with application of a plant growth regulator (BAP) and citric acid.

PubMed

Aderholt, Matthew; Vogelien, Dale L; Koether, Marina; Greipsson, Sigurdur

2017-05-01

Lead (Pb) contamination in soil represents a threat to human health. Phytoextraction has gained attention as a potential alternative to traditional remediation methods because of lower cost and minimal soil disruption. The North American native switchgrass (Panicum virgatum L.) was targeted due to its ability to produce high biomass and grow across a variety of ecozones. In this study switchgrass was chemically enhanced with applications of the soil-fungicide benomyl, chelates (EDTA and citric acid), and PGR to optimize phytoextraction of Pb and zinc (Zn) from contaminated urban soils in Atlanta, GA. Exogenous application of two plant hormones was compared in multiple concentrations to determine effects on switchgrass growth: indole-3-acetic acid (IAA), and Gibberellic Acid (GA 3 ), and one PGR benzylaminopurine (BAP), The PGR BAP (1.0 μM) was found to generate a 48% increase in biomass compared to Control plants. Chemical application of citric acid, EDTA, benomyl, and BAP were tested separately and in combination in a pot experiment in an environmentally controlled greenhouse to determine the efficacy of phtyoextraction by switchgrass. Soil acidification by citric acid application resulted in highest level of aluminum (Al) and iron (Fe) in plants foliage resulting in severe phytotoxic effects. Total Pb phytoextraction was significantly highest in plants treated with combined chemical application of B + C and B + C + H. Suppression of AMF activities by benomyl application significantly increased concentrations of Al and Fe in roots. Application of benomyl reduced AMF colonization but was also shown to dramatically increase levels of septa fungi infection as compared to Control plants. Copyright © 2017 Elsevier Ltd. All rights reserved.

Production of citric acid using its extraction wastewater treated by anaerobic digestion and ion exchange in an integrated citric acid-methane fermentation process.

PubMed

Xu, Jian; Chen, Yang-Qiu; Zhang, Hong-Jian; Tang, Lei; Wang, Ke; Zhang, Jian-Hua; Chen, Xu-Sheng; Mao, Zhong-Gui

2014-08-01

In order to solve the problem of extraction wastewater pollution in citric acid industry, an integrated citric acid-methane fermentation process is proposed in this study. Extraction wastewater was treated by mesophilic anaerobic digestion and then used to make mash for the next batch of citric acid fermentation. The recycling process was done for seven batches. Citric acid production (82.4 g/L on average) decreased by 34.1 % in the recycling batches (2nd-7th) compared with the first batch. And the residual reducing sugar exceeded 40 g/L on average in the recycling batches. Pigment substances, acetic acid, ammonium, and metal ions in anaerobic digestion effluent (ADE) were considered to be the inhibitors, and their effects on the fermentation were studied. Results indicated that ammonium, Na(+) and K(+) in the ADE significantly inhibited citric acid fermentation. Therefore, the ADE was treated by acidic cation exchange resin prior to reuse to make mash for citric acid fermentation. The recycling process was performed for ten batches, and citric acid productions in the recycling batches were 126.6 g/L on average, increasing by 1.7 % compared with the first batch. This process could eliminate extraction wastewater discharge and reduce water resource consumption.

Cleaner production of citric acid by recycling its extraction wastewater treated with anaerobic digestion and electrodialysis in an integrated citric acid-methane production process.

PubMed

Xu, Jian; Su, Xian-Feng; Bao, Jia-Wei; Chen, Yang-Qiu; Zhang, Hong-Jian; Tang, Lei; Wang, Ke; Zhang, Jian-Hua; Chen, Xu-Sheng; Mao, Zhong-Gui

2015-01-01

To solve the pollution problem of extraction wastewater in citric acid production, an integrated citric acid-methane production process was proposed. Extraction wastewater was treated through anaerobic digestion and the anaerobic digestion effluent (ADE) was recycled for the next batch of citric acid fermentation, thus eliminating wastewater discharge and reducing water consumption. Excessive Na(+) contained in ADE could significantly inhibit citric acid fermentation in recycling and was removed by electrodialysis in this paper. Electrodialysis performance was improved after pretreatment of ADE with air stripping and activated carbon adsorption to remove precipitable metal ions and pigments. Moreover, the concentrate water was recycled and mixed with feed to improve the water recovery rate above 95% in electrodialysis treatment, while the dilute water was collected for citric acid fermentation. The removal rate of Na(+) in ADE was above 95% and the citric acid production was even higher than that with tap water. Copyright © 2015 Elsevier Ltd. All rights reserved.

Coamorphous Loratadine-Citric Acid System with Enhanced Physical Stability and Bioavailability.

PubMed

Wang, Jin; Chang, Ruimiao; Zhao, Yanan; Zhang, Jiye; Zhang, Ting; Fu, Qiang; Chang, Chun; Zeng, Aiguo

2017-10-01

Coamorphous systems using citric acid as a small molecular excipient were studied for improving physical stability and bioavailability of loratadine, a BCS class II drug with low water solubility and high permeability. Coamorphous loratadine-citric acid systems were prepared by solvent evaporation technique and characterized by differential scanning calorimetry, X-ray powder diffraction, and Fourier transform infrared spectroscopy. Solid-state analysis proofed that coamorphous loratadine-citric acid system (1:1) was amorphous and homogeneous, had a higher T g over amorphous loratadine, and the intermolecular hydrogen bond interactions between loratadine and citric acid exist. The solubility and dissolution of coamorphous loratadine-citric acid system (1:1) were found to be significantly greater than those of crystalline and amorphous form. The pharmacokinetic study in rats proved that coamorphous loratadine-citric acid system (1:1) could significantly improve absorption and bioavailability of loratadine. Coamorphous loratadine-citric acid system (1:1) showed excellently physical stability over a period of 3 months at 25°C under 0% RH and 25°C under 60% RH conditions. The improved stability of coamorphous loratadine-citric acid system (1:1) could be related to an elevated T g over amorphous form and the intermolecular hydrogen bond interactions between loratadine and citric acid. These studies demonstrate that the developed coamorphous loratadine-citric acid system might be a promising oral formulation for improving solubility and bioavailability of loratadine.

Effects of sodium citrate, citric acid and lactic acid on human blood coagulation.

PubMed

Scaravilli, Vittorio; Di Girolamo, Luca; Scotti, Eleonora; Busana, Mattia; Biancolilli, Osvaldo; Leonardi, Patrizia; Carlin, Andrea; Lonati, Caterina; Panigada, Mauro; Pesenti, Antonio; Zanella, Alberto

2018-05-01

Citric acid infusion in extracorporeal blood may allow concurrent regional anticoagulation and enhancement of extracorporeal CO 2 removal. Effects of citric acid on human blood thromboelastography and aggregometry have never been tested before. In this in vitro study, citric acid, sodium citrate and lactic acid were added to venous blood from seven healthy donors, obtaining concentrations of 9 mEq/L, 12 mEq/L and 15 mEq/L. We measured gas analyses, ionized calcium (iCa ++ ) concentration, activated clotting time (ACT), thromboelastography and multiplate aggregometry. Repeated measure analysis of variance was used to compare the acidifying and anticoagulant properties of the three compounds. Sodium citrate did not affect the blood gas analysis. Increasing doses of citric and lactic acid progressively reduced pH and HCO 3 - and increased pCO 2 (p<0.001). Sodium citrate and citric acid similarly reduced iCa ++ , from 0.39 (0.36-0.39) and 0.35 (0.33-0.36) mmol/L, respectively, at 9 mEq/L to 0.20 (0.20-0.21) and 0.21 (0.20-0.23) mmol/L at 15 mEq/L (p<0.001). Lactic acid did not affect iCa ++ (p=0.07). Sodium citrate and citric acid similarly incremented the ACT, from 234 (208-296) and 202 (178-238) sec, respectively, at 9 mEq/L, to >600 sec at 15 mEq/L (p<0.001). Lactic acid did not affect the ACT values (p=0.486). Sodium citrate and citric acid similarly incremented R-time and reduced α-angle and maximum amplitude (MA) (p<0.001), leading to flat-line thromboelastograms at 15 mEq/L. Platelet aggregometry was not altered by any of the three compounds. Citric acid infusions determine acidification and anticoagulation of blood similar to lactic acid and sodium citrate, respectively.

21 CFR 173.280 - Solvent extraction process for citric acid.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Solvent extraction process for citric acid. 173..., Lubricants, Release Agents and Related Substances § 173.280 Solvent extraction process for citric acid. A solvent extraction process for recovery of citric acid from conventional Aspergillus niger fermentation...

Germanium oxide removal by citric acid and thiol passivation from citric acid-terminated Ge(100).

PubMed

Collins, Gillian; Aureau, Damien; Holmes, Justin D; Etcheberry, Arnaud; O'Dwyer, Colm

2014-12-02

Many applications of germanium (Ge) are underpinned by effective oxide removal and surface passivation. This important surface treatment step often requires H-X (X = Cl, Br, I) or HF etchants. Here, we show that aqueous citric acid solutions are effective in the removal of GeOx. The stability of citric acid-treated Ge(100) is compared to HF and HCl treated surfaces and analyzed by X-ray photoelectron spectroscopy. Further Ge surface passivation was investigated by thiolation using alkane monothiols and dithiols. The organic passivation layers show good stability with no oxide regrowth observed after 3 days of ambient exposure.

Comparison of EDTA and EDDS as potential soil amendments for enhanced phytoextraction of heavy metals.

PubMed

Meers, E; Ruttens, A; Hopgood, M J; Samson, D; Tack, F M G

2005-02-01

Phytoextraction has been proposed as an alternative remediation technology for soils polluted with heavy metals or radionuclides, but is generally conceived as too slow working. Enhancing the accumulation of trace pollutants in harvestable plant tissues is a prerequisite for the technology to be practically applicable. The chelating aminopolycarboxylic acid, ethylene diamine tetraacetate (EDTA), has been found to enhance shoot accumulation of heavy metals. However, the use of EDTA in phytoextraction may not be suitable due to its high environmental persistence, which may lead to groundwater contamination. This paper aims to assess whether ethylene diamine disuccinate (EDDS), a biodegradable chelator, can be used for enhanced phytoextraction purposes. A laboratory experiment was conducted to examine mobilisation of Cd, Cu, Cr, Ni, Pb and Zn into the soil solution upon application of EDTA or EDDS. The longevity of the induced mobilisation was monitored for a period of 40 days after application. Estimated effect half lives ranged between 3.8 and 7.5 days for EDDS, depending on the applied dose. The minimum observed effect half life of EDTA was 36 days, while for the highest applied dose no decrease was observed throughout the 40 day period of the mobilisation experiment. Performance of EDTA and EDDS for phytoextraction was evaluated by application to Helianthus annuus. Two other potential chelators, known for their biodegradability in comparison to EDTA, were tested in the plant experiment: nitrilo acetic acid (NTA) and citric acid. Uptake of heavy metals was higher in EDDS-treated pots than in EDTA-treated pots. The effects were still considered insufficiently high to consider efficient remediation. This may be partly due to the choice of timing for application of the soil amendment. Fixing the time of application at an earlier point before harvest may yield better results. NTA and citric acid induced no significant effects on heavy metal uptake.

Citric Acid Alternative to Nitric Acid Passivation

NASA Technical Reports Server (NTRS)

Lewis, Pattie L. (Compiler)

2013-01-01

The Ground Systems Development and Operations GSDO) Program at NASA John F. Kennedy Space Center (KSC) has the primary objective of modernizing and transforming the launch and range complex at KSC to benefit current and future NASA programs along with other emerging users. Described as the launch support and infrastructure modernization program in the NASA Authorization Act of 2010, the GSDO Program will develop and implement shared infrastructure and process improvements to provide more flexible, affordable, and responsive capabilities to a multi-user community. In support of the GSDO Program, the purpose of this project is to demonstratevalidate citric acid as a passivation agent for stainless steel. Successful completion of this project will result in citric acid being qualified for use as an environmentally preferable alternative to nitric acid for passivation of stainless steel alloys in NASA and DoD applications.

Comparison of the effect of root surface modification with citric acid, EDTA, and aPDT on adhesion and proliferation of human gingival fibroblasts and osteoblasts: an in vitro study.

PubMed

Ferreira, Rafael; de Toledo Barros, Renato Taddei; Karam, Paula Stephania Brandão Hage; Sant'Ana, Adriana Campos Passanezi; Greghi, Sebastião Luiz Aguiar; de Rezende, Maria Lucia Rubo; Zangrando, Mariana Schutzer Ragghianti; de Oliveira, Rodrigo Cardoso; Damante, Carla Andreotti

2018-04-01

Root demineralization is used in Periodontics as an adjuvant for mechanical treatment. The aim of this study was to evaluate the effects of root surface modification with mechanic, chemical, and photodynamic treatments on adhesion and proliferation of human gingival fibroblasts and osteoblasts. Root fragments were treated by scaling and root planing (C-control group), EDTA (pH 7), citric acid plus tetracycline (CA-pH 1), and antimicrobial photodynamic therapy (aPDT) with toluidine blue O and red laser (pH 4). Cells were seeded (104 cells/well, 6th passage) on root fragments of each experimental group and cultured for 24, 48, and 72 h. Cells were counted in scanning electron microscopy images by a calibrated examiner. For fibroblasts, the highest number of cells were present at 72-h period (p < 0.05). EDTA group showed a very low number of cells in relation to CA group (p < 0.05). CA and aPDT group presented higher number of cells in all periods, but without differences between other treatment groups (p > 0.05). For osteoblasts, there was a significant increase in cell numbers for aPDT group at 72 h (p < 0.05). In conclusion, aPDT treatment provided a positive stimulus to osteoblast growth, while for fibroblasts, aPDT and CA had a tendency for higher cell growth.

Biomass pyrolysis liquid to citric acid via 2-step bioconversion.

PubMed

Yang, Zhiguang; Bai, Zhihui; Sun, Hongyan; Yu, Zhisheng; Li, Xingxing; Guo, Yifei; Zhang, Hongxun

2014-12-31

The use of fossil carbon sources for fuels and petrochemicals has serious impacts on our environment and is unable to meet the demand in the future. A promising and sustainable alternative is to substitute fossil carbon sources with microbial cell factories converting lignocellulosic biomass into desirable value added products. However, such bioprocesses require tolerance to inhibitory compounds generated during pretreatment of biomass. In this study, the process of sequential two-step bio-conversion of biomass pyrolysis liquid containing levoglucosan (LG) to citric acid without chemical detoxification has been explored, which can greatly improve the utilization efficiency of lignocellulosic biomass. The sequential two-step bio-conversion of corn stover pyrolysis liquid to citric acid has been established. The first step conversion by Phanerochaete chrysosporium (P. chrysosporium) is desirable to decrease the content of other compounds except levoglucosan as a pretreatment for the second conversion. The remaining levoglucosan in solution was further converted into citric acid by Aspergillus niger (A. niger) CBX-209. Thus the conversion of cellulose to citric acid is completed by both pyrolysis and bio-conversion technology. Under experimental conditions, levoglucosan yield is 12% based on the feedstock and the citric acid yield can reach 82.1% based on the levoglucosan content in the pyrolysis liquid (namely 82.1 g of citric acid per 100 g of levoglucosan). The study shows that P. chrysosporium and A. niger have the potential to be used as production platforms for value-added products from pyrolyzed lignocellulosic biomass. Selected P. chrysosporium is able to decrease the content of other compounds except levoglucosan and levoglucosan can be further converted into citric acid in the residual liquids by A. niger. Thus the conversion of cellulose to citric acid is completed by both pyrolysis and bio-conversion technology.

Citric Acid Production by Aspergillus niger Cultivated on Parkia biglobosa Fruit Pulp

PubMed Central

Abidoye, Khadijat Toyin; Tahir, Hauwa; Ibrahim, Aliyu Dabai; Aransiola, Sesan Abiodun

2014-01-01

The study was conducted to investigate the potential of Parkia biglobosa fruit pulp as substrate for citric acid production by Aspergillus niger. Reducing sugar was estimated by 3,5-dinitrosalicylic acid and citric acid was estimated spectrophotometrically using pyridine-acetic anhydride methods. The studies revealed that production parameters (pH, inoculum size, substrate concentration, incubation temperature, and fermentation period) had profound effect on the amount of citric acid produced. The maximum yield was obtained at the pH of 2 with citric acid of 1.15 g/L and reducing sugar content of 0.541 mMol−1, 3% vegetative inoculum size with citric acid yield of 0.53 g/L and reducing sugar content of 8.87 mMol−1, 2% of the substrate concentration with citric acid yield of 0.83 g/L and reducing sugar content of 9.36 mMol−1, incubation temperature of 55°C with citric acid yield of 0.62 g/L and reducing sugar content of 8.37 mMol−1, and fermentation period of 5 days with citric acid yield of 0.61 g/L and reducing sugar content of 3.70 mMol−1. The results of this study are encouraging and suggest that Parkia biglobosa pulp can be harnessed at low concentration for large scale citric acid production. PMID:27433535

Effects of the food additive, citric acid, on kidney cells of mice.

PubMed

Chen, Xg; Lv, Qx; Liu, Ym; Deng, W

2015-01-01

Citric acid is a food additive that is widely used in the food and drink industry. We investigated the effects of citric acid injection on mouse kidney. Forty healthy mice were divided into four groups of 10 including one control group and three citric acid-treated groups. Low dose, middle dose and high dose groups were given doses of 120, 240 and 480 mg/kg of citric acid, respectively. On day 7, kidney tissues were collected for histological, biochemical and molecular biological examination. We observed shrinkage of glomeruli, widened urinary spaces and capillary congestion, narrowing of the tubule lumen, edema and cytoplasmic vacuolated tubule cells, and appearance of pyknotic nuclei. The relation between histopathological changes and citric acid was dose dependent. Compared to the control, T-SOD and GSH-Px activities in the treated groups decreased with increasing doses of citric acid, NOS activity tended to increase, and H2O2 and MDA contents gradually decreased, but the differences between any treated group and the control were not statistically significant. The apoptosis assay showed a dose-dependent increase of caspase-3 activity after administering citrate that was statistically significant. DNA ladder formation occurred after treatment with any dose of citric acid. We concluded that administration of citric acid may cause renal toxicity in mice.

Electrodeposited Fe-Co films prepared from a citric-acid-based plating bath

NASA Astrophysics Data System (ADS)

Yanai, T.; Uto, H.; Shimokawa, T.; Nakano, M.; Fukunaga, H.; Suzuki, K.

2013-06-01

Electrodeposited Fe-Co films are commonly prepared in a boric-acid-based bath. In this research, we applied citric acid instead of boric acid for the plating of Fe-Co films because boron in the waste bath is restricted by environmental-protection regulations in Japan. We evaluated the effect of citric acid on the magnetic and structural properties of the films. The saturation magnetization of the Fe-Co films slightly increased while the Fe content in the Fe-Co films decreased with increasing citric acid concentration. The lowest coercivity value of 240 A/m was obtained at a citric acid concentration of 100 g/L. The plating bath with this citric acid concentration enabled us to obtain Fe-Co films with high saturation magnetizations and smooth surface morphologies.

Citric Acid Suppresses the Bitter Taste of Olopatadine Hydrochloride Orally Disintegrating Tablets.

PubMed

Sotoyama, Mai; Uchida, Shinya; Tanaka, Shimako; Hakamata, Akio; Odagiri, Keiichi; Inui, Naoki; Watanabe, Hiroshi; Namiki, Noriyuki

2017-01-01

Orally disintegrating tablets (ODTs) are formulated to disintegrate upon contact with saliva, allowing administration without water. Olopatadine hydrochloride, a second-generation antihistamine, is widely used for treating allergic rhinitis. However, it has a bitter taste; therefore, the development of taste-masked olopatadine ODTs is essential. Some studies have suggested that citric acid could suppress the bitterness of drugs. However, these experiments were performed using solutions, and the taste-masking effect of citric acid on ODTs has not been evaluated using human gustatory sensation tests. Thus, this study evaluated citric acid's taste-masking effect on olopatadine ODTs. Six types of olopatadine ODTs containing 0-10% citric acid were prepared and subjected to gustatory sensation tests that were scored using the visual analog scale. The bitterness and overall palatability of olopatadine ODTs during disintegration in the mouth and after spitting out were evaluated in 11 healthy volunteers (age: 22.8±2.2 years). The hardness of the ODTs was >50 N. Disintegration time and dissolution did not differ among the different ODTs. The results of the gustatory sensation tests suggest that citric acid could suppress the bitterness of olopatadine ODTs in a dose-dependent manner. Olopatadine ODTs with a high content of citric acid (5-10%) showed poorer overall palatability than that of those without citric acid despite the bitterness suppression. ODTs containing 2.5% citric acid, yogurt flavoring, and aspartame were the most suitable formulations since they showed low bitterness and good overall palatability. Thus, citric acid is an effective bitterness-masking option for ODTs.

Fermentative production of high titer citric acid from corn stover feedstock after dry dilute acid pretreatment and biodetoxification.

PubMed

Zhou, Ping-Ping; Meng, Jiao; Bao, Jie

2017-01-01

The aim of this work is to study the citric acid fermentation by a robust strain Aspergillus niger SIIM M288 using corn stover feedstock after dry dilute sulfuric acid pretreatment and biodetoxification. Citric acid at 100.04g/L with the yield of 94.11% was obtained, which are comparable to the starch or sucrose based citric acid fermentation. No free wastewater was generated in the overall process from the pretreatment to citric acid fermentation. Abundant divalent metal ions as well as high titer of potassium, phosphate, and nitrogen were found in corn stover hydrolysate. Further addition of extra nutrients showed no impact on increasing citric acid formation except minimum nitrogen source was required. Various fermentation parameters were tested and only minimum regulation was required during the fermentation. This study provided a biorefining process for citric acid fermentation from lignocellulose feedstock with the maximum citric acid titer and yield. Copyright © 2016 Elsevier Ltd. All rights reserved.

Citric acid effects on brain and liver oxidative stress in lipopolysaccharide-treated mice.

PubMed

Abdel-Salam, Omar M E; Youness, Eman R; Mohammed, Nadia A; Morsy, Safaa M Youssef; Omara, Enayat A; Sleem, Amany A

2014-05-01

Citric acid is a weak organic acid found in the greatest amounts in citrus fruits. This study examined the effect of citric acid on endotoxin-induced oxidative stress of the brain and liver. Mice were challenged with a single intraperitoneal dose of lipopolysaccharide (LPS; 200 μg/kg). Citric acid was given orally at 1, 2, or 4 g/kg at time of endotoxin injection and mice were euthanized 4 h later. LPS induced oxidative stress in the brain and liver tissue, resulting in marked increase in lipid peroxidation (malondialdehyde [MDA]) and nitrite, while significantly decreasing reduced glutathione, glutathione peroxidase (GPx), and paraoxonase 1 (PON1) activity. Tumor necrosis factor-alpha (TNF-α) showed a pronounced increase in brain tissue after endotoxin injection. The administration of citric acid (1-2 g/kg) attenuated LPS-induced elevations in brain MDA, nitrite, TNF-α, GPx, and PON1 activity. In the liver, nitrite was decreased by 1 g/kg citric acid. GPx activity was increased, while PON1 activity was decreased by citric acid. The LPS-induced liver injury, DNA fragmentation, serum transaminase elevations, caspase-3, and inducible nitric oxide synthase expression were attenuated by 1-2 g/kg citric acid. DNA fragmentation, however, increased after 4 g/kg citric acid. Thus in this model of systemic inflammation, citric acid (1-2 g/kg) decreased brain lipid peroxidation and inflammation, liver damage, and DNA fragmentation.

Citric Acid Effects on Brain and Liver Oxidative Stress in Lipopolysaccharide-Treated Mice

PubMed Central

Youness, Eman R.; Mohammed, Nadia A.; Morsy, Safaa M. Youssef; Omara, Enayat A.; Sleem, Amany A.

2014-01-01

Abstract Citric acid is a weak organic acid found in the greatest amounts in citrus fruits. This study examined the effect of citric acid on endotoxin-induced oxidative stress of the brain and liver. Mice were challenged with a single intraperitoneal dose of lipopolysaccharide (LPS; 200 μg/kg). Citric acid was given orally at 1, 2, or 4 g/kg at time of endotoxin injection and mice were euthanized 4 h later. LPS induced oxidative stress in the brain and liver tissue, resulting in marked increase in lipid peroxidation (malondialdehyde [MDA]) and nitrite, while significantly decreasing reduced glutathione, glutathione peroxidase (GPx), and paraoxonase 1 (PON1) activity. Tumor necrosis factor-alpha (TNF-α) showed a pronounced increase in brain tissue after endotoxin injection. The administration of citric acid (1–2 g/kg) attenuated LPS-induced elevations in brain MDA, nitrite, TNF-α, GPx, and PON1 activity. In the liver, nitrite was decreased by 1 g/kg citric acid. GPx activity was increased, while PON1 activity was decreased by citric acid. The LPS-induced liver injury, DNA fragmentation, serum transaminase elevations, caspase-3, and inducible nitric oxide synthase expression were attenuated by 1–2 g/kg citric acid. DNA fragmentation, however, increased after 4 g/kg citric acid. Thus in this model of systemic inflammation, citric acid (1–2 g/kg) decreased brain lipid peroxidation and inflammation, liver damage, and DNA fragmentation. PMID:24433072

Synergistic effect of EDTA and boric acid on corneal penetration of CS-088.

PubMed

Kikuchi, Takayuki; Suzuki, Masahiko; Kusai, Akira; Iseki, Ken; Sasaki, Hitoshi

2005-02-16

In order to investigate the effects of EDTA and boric acid (EDTA/boric acid) on the corneal penetration of CS-088, an ophthalmic agent, the apparent permeability coefficient of CS-088 in the presence of EDTA/boric acid across the isolated corneal membranes of rabbits was measured using an in vitro penetration chamber system. FITC-dextran (M.W. 4400) and an electrical method based on membrane resistance were used to provide a quantitative assessment of the enhancing effect of EDTA/boric acid. The corneal penetration of CS-088 was significantly enhanced in the presence of EDTA/boric acid by approximately 1.6-fold. The permeability-enhancing effect of EDTA/boric acid was apparently synergistic and concentration-dependent on both EDTA and boric acid. The penetration of FITC-dextran, a paracellular marker, and electrical resistance of corneal membranes were not affected in the presence of EDTA/boric acid. Furthermore, no enhancing effect of EDTA/boric acid was observed in de-epithelialized corneas, although de-epithelialized corneas exhibited a markedly higher permeability of CS-088 that was 24-fold greater than that for intact corneas. In conclusion, EDTA/boric acid synergistically enhances the transcellular permeability of CS-088 in the outer layer but not in the inner layers of the corneal membrane.

A novel cleaner production process of citric acid by recycling its treated wastewater.

PubMed

Xu, Jian; Su, Xian-Feng; Bao, Jia-Wei; Zhang, Hong-Jian; Zeng, Xin; Tang, Lei; Wang, Ke; Zhang, Jian-Hua; Chen, Xu-Sheng; Mao, Zhong-Gui

2016-07-01

In this study, a novel cleaner production process of citric acid was proposed to completely solve the problem of wastewater management in citric acid industry. In the process, wastewater from citric acid fermentation was used to produce methane through anaerobic digestion and then the anaerobic digestion effluent was further treated with air stripping and electrodialysis before recycled as process water for the later citric acid fermentation. This proposed process was performed for 10 batches and the average citric acid production in recycling batches was 142.4±2.1g/L which was comparable to that with tap water (141.6g/L). Anaerobic digestion was also efficient and stable in operation. The average chemical oxygen demand (COD) removal rate was 95.1±1.2% and methane yield approached to 297.7±19.8mL/g TCODremoved. In conclusion, this novel process minimized the wastewater discharge and achieved the cleaner production in citric acid industry. Copyright © 2016 Elsevier Ltd. All rights reserved.

Citric acid-assisted phytoextraction of lead: a field experiment.

PubMed

Freitas, Eriberto Vagner; Nascimento, Clístenes Williams; Souza, Adailson; Silva, Fernando Bruno

2013-06-01

Soil contamination with heavy metals has become a serious environmental problem that requires affordable strategies of remediation. This study was carried out to assess the performance of maize and vetiver in the phytoextraction of Pb from a soil contaminated by battery recycling activities. The species were planted with different spacings between rows (0.80, 0.65 and 0.50m). Citric acid (40mmolkg(-1)) was applied on each experimental plot on the 61st d of cultivation in order to solubilize the Pb and assist the phytoextraction. The results showed that the chelating agent promoted a 14-fold increase in the Pb concentration in maize shoots as compared to the control, which accumulated only 111mgkg(-1) of the metal. The citric acid induced a Pb concentration in vetiver shoots that was 7.2-6.7-fold higher than the control at both the 0.65 and 0.50m plant spacing, respectively. The use of citric acid increased substantially the uptake and translocation of Pb to the shoots, regardless of plant spacing. Citric acid was efficient in solubilizing Pb from the soil and inducing its uptake by both species. Environmentally-friendly and cost effective, commercial citric acid is recommended for assisting Pb-phytoextraction in the studied area. Due to the low natural solubility of Pb and a time frame needed of longer than 150yr to accomplish the clean-up, phytoextraction with no chelate assistance is not recommended for the area. Copyright © 2013 Elsevier Ltd. All rights reserved.

21 CFR 184.1033 - Citric acid.

Code of Federal Regulations, 2010 CFR

2010-04-01

... lemon or pineapple juice; by mycological fermentation using Candida spp., described in §§ 173.160 and... for the recovery of citric acid from Aspergillus niger fermentation liquor. (b) The ingredient meets...

Roles of oxygen radicals and elastase in citric acid-induced airway constriction of guinea-pigs

PubMed Central

Lai, Y -L; Chiou, W -Y; Lu, F J; Chiang, L Y

1999-01-01

Antioxidants attenuate noncholinergic airway constriction. To further investigate the relationship between tachykinin-mediated airway constriction and oxygen radicals, we explored citric acid-induced bronchial constriction in 48 young Hartley strain guinea-pigs, divided into six groups: control; citric acid; hexa(sulphobutyl)fullerenes+citric acid; hexa(sulphobutyl)fullerenes+phosphoramidon+citric acid; dimethylthiourea (DMTU)+citric acid; and DMTU+phosphoramidon+citric acid. Hexa(sulphobutyl)fullerenes and DMTU are scavengers of oxygen radicals while phosphoramidon is an inhibitor of the major degradation enzyme for tachykinins. Animals were anaesthetized, paralyzed, and artificially ventilated. Each animal was given 50 breaths of 4 ml saline or citric acid aerosol. We measured dynamic respiratory compliance (Crs), forced expiratory volume in 0.1 (FEV0.1), and maximal expiratory flow at 30% total lung capacity (V[dot above]max30) to evaluate the degree of airway constriction. Citric acid, but not saline, aerosol inhalation caused marked decreases in Crs, FEV0.1 and V[dot above]max30, indicating marked airway constriction. This constriction was significantly attenuated by either hexa(sulphobutyl)fullerenes or by DMTU. In addition, phosphoramidon significantly reversed the attenuating action of hexa(sulphobutyl)fullerenes, but not that of DMTU. Citric acid aerosol inhalation caused increases in both lucigenin- and t-butyl hydroperoxide-initiated chemiluminescence counts, indicating citric acid-induced increase in oxygen radicals and decrease in antioxidants in bronchoalveolar lavage fluid. These alterations were significantly suppressed by either hexa(sulphobutyl)fullerenes or DMTU. An elastase inhibitor eglin-c also significantly attenuated citric acid-induced airway constriction, indicating the contributing role of elastase in this type of constriction. We conclude that both oxygen radicals and elastase play an important role in tachykinin-mediated, citric acid

Citric acid production using immobilized conidia of Aspergillus niger TMB 2022

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsay, S.S.; To, K.Y.

1987-02-20

Conidia of Aspergillus niger TMB 2022 were immobilized in calcium alginate for the production of citric acid. A 1-ml condidia suspension containing ca. 2.32 x 10/sup 8/ conidia were entrapped into sodium alginate solution in order to prepare 3% Ca-alginate (w/v) gel bead. Immobilized conidia were inoculated into productive medium containing 14% sucrose, 0.25% (NH/sub 4/)/sub 2/CO/sub 3/, 0.25% KH/sub 2/PO/sub 4/, and 0.025% MgSO/sub 4/.7H/sub 2/O with addition of 0.06 mg/l CuSO/sub 4/.5H/sub 2/O, 0.25 mg/l ZnCl/sub 2/, 1.3 mg/l FeCl/sub 3/.6H/sub 2/O, pH 3.8, and incubated at 35 degrees C for 13 days by surface culture to producemore » 61.53 g/l anhydrous citric acid. Under the same conditions with a batchwise culture, it was found that immobilized conidia could maintain a longer period for citric acid production (31 days): over 70 g/l anhydrous citric acid from runs No. 2-4, with the maximum yield for anhydrous citric acid reaching 77.02 g/l for run No. 2. In contrast, free conidia maintained a shorter acid-producing phase, circa 17 days; the maximum yield for anhydrous citric acid was 71.07 g/l for run No. 2 but dropped quickly as the run number increased. 14 references.« less

Properties of polyvinyl alcohol/xylan composite films with citric acid.

PubMed

Wang, Shuaiyang; Ren, Junli; Li, Weiying; Sun, Runcang; Liu, Shijie

2014-03-15

Composite films of xylan and polyvinyl alcohol were produced with citric acid as a new plasticizer or a cross-linking agent. The effects of citric acid content and polyvinyl alcohol/xylan weight ratio on the mechanical properties, thermal stability, solubility, degree of swelling and water vapor permeability of the composite films were investigated. The intermolecular interactions and morphology of composite films were characterized by FTIR spectroscopy and SEM. The results indicated that polyvinyl alcohol/xylan composite films had good compatibility. With an increase in citric acid content from 10% to 50%, the tensile strength reduced from 35.1 to 11.6 MPa. However, the elongation at break increased sharply from 15.1% to 249.5%. The values of water vapor permeability ranged from 2.35 to 2.95 × 10(-7)g/(mm(2)h). Interactions between xylan and polyvinyl alcohol in the presence of citric acid become stronger, which were caused by hydrogen bond and ester bond formation among the components during film forming. Copyright © 2013. Published by Elsevier Ltd.

Esterification of pseudoephedrine hydrochloride by citric acid in a solid dose pharmaceutical preparation.

PubMed

Goel, Alok; Zhao, Zhicheng; Sørensen, Dan; Zhou, Jay; Zhang, Fa

2016-09-10

Esterification of pseudoephedrine hydrochloride (PSE) by citric acid was observed in a solid dose pharmaceutical preparation at room temperature and accelerated stability condition (40°C/75% relative humidity). The esterification of PSE with citric acid was confirmed by a solid-state binary reaction in the presence of minor level of water at elevated temperature to generate three isomeric esters. The structures of the pseudoephedrine citric acid esters were elucidated using high-resolution mass spectrometry and nuclear magnetic resonance spectroscopy (NMR). Occurrence of esterification in solid state, instead of amidation which is generally more favorable than esterification, is likely due to remaining HCl salt form of solid pseudoephedrine hydrochloride to protect its amino group from amidation with citric acid. In contrast, the esterification was not observed from solution reaction between PSE and citric acid. Copyright © 2016 Elsevier B.V. All rights reserved.

Inhibition of oxidative phosphorylation for enhancing citric acid production by Aspergillus niger.

PubMed

Wang, Lu; Zhang, Jianhua; Cao, Zhanglei; Wang, Yajun; Gao, Qiang; Zhang, Jian; Wang, Depei

2015-01-16

The spore germination rate and growth characteristics were compared between the citric acid high-yield strain Aspergillus niger CGMCC 5751 and A. niger ATCC 1015 in media containing antimycin A or DNP. We inferred that differences in citric acid yield might be due to differences in energy metabolism between these strains. To explore the impact of energy metabolism on citric acid production, the changes in intracellular ATP, NADH and NADH/NAD+ were measured at various fermentation stages. In addition, the effects of antimycin A or DNP on energy metabolism and citric acid production was investigated by CGMCC 5751. By comparing the spore germination rate and the extent of growth on PDA plates containing antimycin A or DNP, CGMCC 5751 was shown to be more sensitive to antimycin A than ATCC 1015. The substrate-level phosphorylation of CGMCC 5751 was greater than that of ATCC 1015 on PDA plates with DNP. DNP at tested concentrations had no apparent effect on the growth of CGMCC 5751. There were no apparent effects on the mycelial morphology, the growth of mycelial pellets or the dry cell mass when 0.2 mg L(-1) antimycin A or 0.1 mg L(-1) DNP was added to medium at the 24-h time point. The concentrations of intracellular ATP, NADH and NADH/NAD+ of CGMCC 5751 were notably lower than those of ATCC 1015 at several fermentation stages. Moreover, at 96 h of fermentation, the citric acid production of CGMCC 5751 reached up to 151.67 g L(-1) and 135.78 g L(-1) by adding 0.2 mg L(-1) antimycin A or 0.1 mg L(-1) DNP, respectively, at the 24-h time point of fermentation. Thus, the citric acid production of CGMCC 5751 was increased by 19.89% and 7.32%, respectively. The concentrations of intracellular ATP, NADH and NADH/NAD+ of the citric acid high-yield strain CGMCC 5751 were notably lower than those of ATCC 1015. The excessive ATP has a strong inhibitory effect on citric acid accumulation by A. niger. Increasing NADH oxidation and appropriately reducing the concentration of

7 CFR 51.1178 - Maximum anhydrous citric acid permissible for corresponding total soluble solids.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 2 2012-01-01 2012-01-01 false Maximum anhydrous citric acid permissible for... Sinensis (l) Osbeck) § 51.1178 Maximum anhydrous citric acid permissible for corresponding total soluble solids. For determining the grade of juice, the maximum permissible anhydrous citric acid content in...

7 CFR 51.1178 - Maximum anhydrous citric acid permissible for corresponding total soluble solids.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 2 2011-01-01 2011-01-01 false Maximum anhydrous citric acid permissible for... Sinensis (l) Osbeck) § 51.1178 Maximum anhydrous citric acid permissible for corresponding total soluble solids. For determining the grade of juice, the maximum permissible anhydrous citric acid content in...

78 FR 34338 - Citric Acid and Certain Citrate Salts From Canada: Preliminary Results of Antidumping Duty...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-07

... DEPARTMENT OF COMMERCE International Trade Administration [A-122-853] Citric Acid and Certain... on citric acid and certain citrate salts (citric acid) from Canada. The period of review (POR) is May... INFORMATION: Scope of the Order The merchandise covered by this order is citric acid and certain citrate salts...

Method for the isolation of citric acid and malic acid in Japanese apricot liqueur for carbon stable isotope analysis.

PubMed

Akamatsu, Fumikazu; Hashiguchi, Tomokazu; Hisatsune, Yuri; Oe, Takaaki; Kawao, Takafumi; Fujii, Tsutomu

2017-02-15

A method for detecting the undeclared addition of acidic ingredients is required to control the authenticity of Japanese apricot liqueur. We developed an analytical procedure that minimizes carbon isotope discrimination for measurement of the δ(13)C values of citric and malic acid isolated from Japanese apricot liqueur. Our results demonstrated that freeze-drying is preferable to nitrogen spray-drying, because it does not significantly affect the δ(13)C values of citric acid and results in smaller isotope discrimination for malic acid. Both 0.1% formic acid and 0.2% phosphoric acid are acceptable HPLC mobile phases for the isolation of citric and malic acid, although the δ(13)C values of malic acid exhibited relatively large variation compared with citric acid following isolation using either mobile phase. The developed procedure allows precise δ(13)C measurements of citric and malic acid isolated from Japanese apricot liqueur. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of Periodic Water Addition on Citric Acid Production in Solid State Fermentation

NASA Astrophysics Data System (ADS)

Utpat, Shraddha S.; Kinnige, Pallavi T.; Dhamole, Pradip B.

2013-09-01

Water addition is one of the methods used to control the moisture loss in solid state fermentation (SSF). However, none of the studies report the timing of water addition and amount of water to be added in SSF. Therefore, this work was undertaken with an objective to evaluate the performance of periodic water addition on citric acid production in SSF. Experiments were conducted at different moistures (50-80 %) and temperatures (30-40 °C) to simulate the conditions in a fermenter. Citric acid production by Aspergillus niger (ATCC 9029) using sugarcane baggase was chosen as a model system. Based on the moisture profile, citric acid and sugar data, a strategy was designed for periodic addition of water. Water addition at 48, 96, 144 and 192 h enhanced the citric acid production by 62 % whereas water addition at 72, 120, and 168 h increased the citric acid production by just 17 %.

7 CFR 51.1178 - Maximum anhydrous citric acid permissible for corresponding total soluble solids.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 2 2013-01-01 2013-01-01 false Maximum anhydrous citric acid permissible for... Common Sweet Oranges (citrus Sinensis (l) Osbeck) § 51.1178 Maximum anhydrous citric acid permissible for... following Table II together with the minimum ratio of total soluble solids to anhydrous citric acid: Table...

7 CFR 51.1178 - Maximum anhydrous citric acid permissible for corresponding total soluble solids.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 2 2014-01-01 2014-01-01 false Maximum anhydrous citric acid permissible for... Common Sweet Oranges (citrus Sinensis (l) Osbeck) § 51.1178 Maximum anhydrous citric acid permissible for... following Table II together with the minimum ratio of total soluble solids to anhydrous citric acid: Table...

The Cardioprotective Effects of Citric Acid and L-Malic Acid on Myocardial Ischemia/Reperfusion Injury

PubMed Central

Tang, Xilan; Liu, Jianxun; Dong, Wei; Li, Peng; Li, Lei; Lin, Chengren; Zheng, Yongqiu; Hou, Jincai; Li, Dan

2013-01-01

Organic acids in Chinese herbs, the long-neglected components, have been reported to possess antioxidant, anti-inflammatory, and antiplatelet aggregation activities; thus they may have potentially protective effect on ischemic heart disease. Therefore, this study aims to investigate the protective effects of two organic acids, that is, citric acid and L-malic acid, which are the main components of Fructus Choerospondiatis, on myocardial ischemia/reperfusion injury and the underlying mechanisms. In in vivo rat model of myocardial ischemia/reperfusion injury, we found that treatments with citric acid and L-malic acid significantly reduced myocardial infarct size, serum levels of TNF-α, and platelet aggregation. In vitro experiments revealed that both citric acid and L-malic acid significantly reduced LDH release, decreased apoptotic rate, downregulated the expression of cleaved caspase-3, and upregulated the expression of phosphorylated Akt in primary neonatal rat cardiomyocytes subjected to hypoxia/reoxygenation injury. These results suggest that both citric acid and L-malic acid have protective effects on myocardial ischemia/reperfusion injury; the underlying mechanism may be related to their anti-inflammatory, antiplatelet aggregation and direct cardiomyocyte protective effects. These results also demonstrate that organic acids, besides flavonoids, may also be the major active ingredient of Fructus Choerospondiatis responsible for its cardioprotective effects and should be attached great importance in the therapy of ischemic heart disease. PMID:23737849

Leaching with Penicillium simplicissimum: Influence of metals and buffers on proton extrusion and citric acid production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Franz, A.; Burgstaller, W.; Schinner, F.

1991-03-01

In the presence of insoluble metal oxides (industrial filter dust, zinc oxide, synthetic mixture of metal oxides), Penicillium simplicissimum developed the ability to excrete considerable amounts of citric acid (>100 mM). Parallel with the increase of citric acid concentration in the culture broth, zinc was solubilized from zinc oxide. The adsorption of filter dust onto the mycelium (the pellets formed were less than 1 mm in diameter) was required for not only the citric acid excretion but also the leaching of zinc. When the filter dust was replaced with a synthetic mixture of metal oxides or with zinc oxide inmore » combination with trace elements, levels of adsorption and citric acid production were observed to be similar to those in experiments where industrial filter dust was used. The two most important properties of the filter dust were its heavy-metal content and its buffering capacity. These properties were simulated by adding heavy metals in soluble form (as chlorides, sulfates, or nitrates) or soluble buffers to the medium. Both heavy metals and buffers were not able to induce a citric acid efflux. As with citric acid production by Aspergillus niger, the addition of manganese lowered citric acid excretion (by 40% with metal oxide-induced citric acid efflux and by 100% with urea-induced citric acid efflux). Copper antagonized the effect of manganese. The mechanism for the bulk of citric acid excretion by P. simplicissimum, however, seemed to be different from that described for citric acid accumulation by A. niger. Because of the inefficiency of metals in solubilized form and of soluble buffers to induce a strong citric acid efflux, adsorption of an insoluble metal compound (zinc oxide) turned out to be essential.« less

76 FR 47146 - Citric Acid and Certain Citrate Salts From the People's Republic of China: Extension of Time...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-04

... DEPARTMENT OF COMMERCE International Trade Administration [A-570-937] Citric Acid and Certain... review of the antidumping duty order on citric acid and certain citrate salts (``citric acid'') from the... of citric acid from the PRC. See Citric Acid and Certain Citrate Salts From the People's Republic of...

Advances in citric acid fermentation by Aspergillus niger: biochemical aspects, membrane transport and modeling.

PubMed

Papagianni, Maria

2007-01-01

Citric acid is regarded as a metabolite of energy metabolism, of which the concentration will rise to appreciable amounts only under conditions of substantive metabolic imbalances. Citric acid fermentation conditions were established during the 1930s and 1940s, when the effects of various medium components were evaluated. The biochemical mechanism by which Aspergillus niger accumulates citric acid has continued to attract interest even though its commercial production by fermentation has been established for decades. Although extensive basic biochemical research has been carried out with A. niger, the understanding of the events relevant for citric acid accumulation is not completely understood. This review is focused on citric acid fermentation by A. niger. Emphasis is given to aspects of fermentation biochemistry, membrane transport in A. niger and modeling of the production process.

Citric acid production by Koji fermentation using banana peel as a novel substrate.

PubMed

Karthikeyan, Alagarsamy; Sivakumar, Nallusamy

2010-07-01

The growing demand for citric acid and the current need for alternative sources have encouraged biotechnologists to search for novel and economical substrates. Koji fermentation was conducted using the peels of banana (Musa acuminata) as an inexpensive substrate for the production of citric acid using Aspergillus niger. Various crucial parameters that affect citric acid production such as moisture content, temperature, pH, inoculum level and incubation time were quantified. Moisture (70%), 28 degrees C temperature, an initial pH 3, 10(8) spores/ml as inoculum and 72h incubation was found to be suitable for maximum citric acid production by A. niger using banana peel as a substrate. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Novel neuroprotective and hepatoprotective effects of citric acid in acute malathion intoxication.

PubMed

Abdel-Salam, Omar M E; Youness, Eman R; Mohammed, Nadia A; Yassen, Noha N; Khadrawy, Yasser A; El-Toukhy, Safinaz Ebrahim; Sleem, Amany A

2016-12-01

To study the effect of citric acid given alone or combined with atropine on brain oxidative stress, neuronal injury, liver damage, and DNA damage of peripheral blood lymphocytes induced in the rat by acute malathion exposure. Rats were received intraperitoneal (i.p.) injection of malathion 150 mg/kg along with citric acid (200 or 400 mg/kg, orally), atropine (1 mg/kg, i.p.) or citric acid 200 mg/kg + atropine 1 mg/kg and euthanized 4 h later. Malathion resulted in increased lipid peroxidation (malondialdehyde) and nitric oxide concentrations accompanied with a decrease in brain reduced glutathione, glutathione peroxidase (GPx) activity, total antioxidant capacity (TAC) and glucose concentrations. Paraoxonase-1, acetylcholinesterase (AChE) and butyrylcholinesterase activities decreased in brain as well. Liver aspartate aminotransferase and alanine aminotransferase activities were raised. The comet assay showed increased DNA damage of peripheral blood lymphocytes. Histological damage and increased expression of inducible nitric oxide synthase (iNOS) were observed in brain and liver. Citric acid resulted in decreased brain lipid peroxidation and nitric oxide. Meanwhile, glutathione, GPx activity, TAC capacity and brain glucose level increased. Brain AChE increased but PON1 and butyrylcholinesterase activities decreased by citric acid. Liver enzymes, the percentage of damaged blood lymphocytes, histopathological alterations and iNOS expression in brain and liver was decreased by citric acid. Meanwhile, rats treated with atropine showed decreased brain MDA, nitrite but increased GPx activity, TAC, AChE and glucose. The drug also decreased DNA damage of peripheral blood lymphocytes, histopathological alterations and iNOS expression in brain and liver. The study demonstrates a beneficial effect for citric acid upon brain oxidative stress, neuronal injury, liver and DNA damage due to acute malathion exposure. Copyright © 2016 Hainan Medical University. Production

Dissolution of Simulated and Radioactive Savannah River Site High-Level Waste Sludges with Oxalic Acid & Citric Acid Solutions

DOE Office of Scientific and Technical Information (OSTI.GOV)

STALLINGS, MARY

This report presents findings from tests investigating the dissolution of simulated and radioactive Savannah River Site sludges with 4 per cent oxalic acid and mixtures of oxalic and citric acid previously recommended by a Russian team from the Khlopin Radium Institute and the Mining and Chemical Combine (MCC). Testing also included characterization of the simulated and radioactive waste sludges. Testing results showed the following: Dissolution of simulated HM and PUREX sludges with oxalic and citric acid mixtures at SRTC confirmed general trends reported previously by Russian testing. Unlike the previous Russian testing six sequential contacts of a mixture of oxalicmore » acid citric acids at a 2:1 ratio (v/w) of acid to sludge did not produce complete dissolution of simulated HM and PUREX sludges. We observed that increased sludge dissolution occurred at a higher acid to sludge ratio, 50:1 (v/w), compared to the recommended ratio of 2:1 (v/w). We observed much lower dissolution of aluminum in a simulated HM sludge by sodium hydroxide leaching. We attribute the low aluminum dissolution in caustic to the high fraction of boehmite present in the simulated sludge. Dissolution of HLW sludges with 4 per cent oxalic acid and oxalic/citric acid followed general trends observed with simulated sludges. The limited testing suggests that a mixture of oxalic and citric acids is more efficient for dissolving HM and PUREX sludges and provides a more homogeneous dissolution of HM sludge than oxalic acid alone. Dissolution of HLW sludges in oxalic and oxalic/citric acid mixtures produced residual sludge solids that measured at higher neutron poison to equivalent 235U weight ratios than that in the untreated sludge solids. This finding suggests that residual solids do not present an increased nuclear criticality safety risk. Generally the neutron poison to equivalent 235U weight ratios of the acid solutions containing dissolved sludge components are lower than those in the

Morphological regulation of Aspergillus niger to improve citric acid production by chsC gene silencing.

PubMed

Sun, Xiaowen; Wu, Hefang; Zhao, Genhai; Li, Zhemin; Wu, Xihua; Liu, Hui; Zheng, Zhiming

2018-04-02

The mycelial morphology of Aspergillus niger, a major filamentous fungus used for citric acid production, is important for citric acid synthesis during submerged fermentation. To investigate the involvement of the chitin synthase gene, chsC, in morphogenesis and citric acid production in A. niger, an RNAi system was constructed to silence chsC and the morphological mutants were screened after transformation. The compactness of the mycelial pellets was obviously reduced in the morphological mutants, with lower proportion of dispersed mycelia. These morphological changes have caused a decrease in viscosity and subsequent improvement in oxygen and mass transfer efficiency, which may be conducive for citric acid accumulation. All the transformants exhibited improvements in citric acid production; in particular, chsC-3 showed 42.6% higher production than the original strain in the shake flask. Moreover, the high-yield strain chsC-3 exhibited excellent citric acid production potential in the scale-up process.The citric acid yield and the conversion rate of glucose of chsC-3 were both improved by 3.6%, when compared with that of the original strain in the stirred tank bioreactor.

Optimization of the integrated citric acid-methane fermentation process by air stripping and glucoamylase addition.

PubMed

Xu, Jian; Chen, Yang-Qiu; Zhang, Hong-Jian; Wang, Ke; Tang, Lei; Zhang, Jian-Hua; Chen, Xu-Sheng; Mao, Zhong-Gui

2015-03-01

To solve the problem of extraction wastewater in citric acid industry, an integrated citric acid-methane fermentation process was proposed. In the integrated process, extraction wastewater was treated by mesophilic anaerobic digestion and then reused to make mash for the next batch of citric acid fermentation. In this study, an Aspergillus niger mutant strain exhibiting resistance to high metal ions concentration was used to eliminate the inhibition of 200 mg/L Na(+) and 300 mg/L K(+) in anaerobic digestion effluent (ADE) and citric acid production increased by 25.0 %. Air stripping was used to remove ammonium, alkalinity, and part of metal ions in ADE before making mash. In consequence, citric acid production was significantly improved but still lower by 6.1 % than the control. Results indicated that metal ions in ADE synergistically inhibited the activity of glucoamylase, thus reducing citric acid production. When 130 U/g glucoamylase was added before fermentation, citric acid production was 141.5 g/L, which was even higher than the control (140.4 g/L). This process could completely eliminate extraction wastewater discharge and reduce water resource consumption.

Citric-Acid-Derived Photo-cross-Linked Biodegradable Elastomers

PubMed Central

Gyawali, Dipendra; Tran, Richard T.; Guleserian, Kristine J.; Tang, Liping; Yang, Jian

2010-01-01

Citric-acid-derived thermally cross-linked biodegradable elastomers (CABEs) have recently received significant attention in various biomedical applications, including tissue-engineering orthopedic devices, bioimaging and implant coatings. However, citric-acid-derived photo-cross-linked biodegradable elastomers are rarely reported. Herein, we report a novel photo-cross-linked biodegradable elastomer, referred to as poly(octamethylene maleate citrate) (POMC), which preserves pendant hydroxyl and carboxylic functionalities after cross-linking for the potential conjugation of biologically active molecules. POMC is a low-molecular-mass pre-polymer with a molecular mass average between 701 and 1291 Da. POMC networks are soft and elastic with an initial modulus of 0.07 to 1.3 MPa and an elongation at break between 38 and 382%. FT-IR–ATR results confirmed the successful surface immobilization of type-I collagen onto POMC films, which enhanced in vitro cellular attachment and proliferation. Photo-polymerized POMC films implanted subcutaneously into Sprague–Dawley rats demonstrated minimal in vivo inflammatory responses. The development of POMC enriches the family of citric-acid-derived biodegradable elastomers and expands the available biodegradable polymers for versatile needs in biomedical applications. PMID:20557687

Establishment and assessment of an integrated citric acid-methane production process.

PubMed

Xu, Jian; Chen, Yang-Qiu; Zhang, Hong-Jian; Bao, Jia-Wei; Tang, Lei; Wang, Ke; Zhang, Jian-Hua; Chen, Xu-Sheng; Mao, Zhong-Gui

2015-01-01

To solve the problem of extraction wastewater in citric acid industrial production, an improved integrated citric acid-methane production process was established in this study. Extraction wastewater was treated by anaerobic digestion and then the anaerobic digestion effluent (ADE) was stripped by air to remove ammonia. Followed by solid-liquid separation to remove metal ion precipitation, the supernatant was recycled for the next batch of citric acid fermentation, thus eliminating wastewater discharge and reducing water consumption. 130U/g glucoamylase was added to medium after inoculation and the recycling process performed for 10 batches. Fermentation time decreased by 20% in recycling and the average citric acid production (2nd-10th) was 145.9±3.4g/L, only 2.5% lower than that with tap water (149.6g/L). The average methane production was 292.3±25.1mL/g CODremoved and stable in operation. Excessive Na(+) concentration in ADE was confirmed to be the major challenge for the proposed process. Copyright © 2014 Elsevier Ltd. All rights reserved.

Citric acid inhibits development of cataracts, proteinuria and ketosis in streptozotocin (type1) diabetic rats

PubMed Central

Nagai, Ryoji; Nagai, Mime; Shimasaki, Satoko; Baynes, John W.; Fujiwara, Yukio

2010-01-01

Although many fruits such as lemon and orange contain citric acid, little is known about beneficial effects of citric acid on health. Here we measured the effect of citric acid on the pathogenesis of diabetic complications in streptozotocin-induced diabetic rats. Although oral administration of citric acid to diabetic rats did not affect blood glucose concentration, it delayed the development of cataracts, inhibited accumulation of advanced glycation end products (AGEs) such as Nε-(carboxyethyl)lysine (CEL) and Nε-(carboxymethyl)lysine (CML) in lens proteins, and protected against albuminuria and ketosis . We also show that incubation of protein with acetol, a metabolite formed from acetone by acetone monooxygenase, generate CEL, suggesting that inhibition of ketosis by citric acid may lead to the decrease in CEL in lens proteins. These results demonstrate that the oral administration of citric acid ameliorates ketosis and protects against the development of diabetic complications in an animal model of type 1 diabetes. PMID:20117096

Utilization of citric acid in wood bonding

USDA-ARS?s Scientific Manuscript database

Citric acid (CA) is a weak organic acid. It exists most notably in citrus fruits so that it is named likewise. As a commodity chemical, CA is produced on a large scale by fermentation. In this chapter, we first briefly review the applied research and methods for commercial production of CA. Then we ...

A Candida guilliermondii lysine hyperproducer capable of elevated citric acid production.

PubMed

West, Thomas P

2016-05-01

A mutant of the yeast Candida guilliermondii ATCC 9058 exhibiting elevated citric acid production was isolated based upon its ability to overproduce lysine. This method involved the use of a solid medium containing a combination of lysine analogues to identify a mutant that produced a several-fold higher lysine level compared to its parent strain using glucose or glycerol as a carbon source. The mutant strain was also capable of producing more than a fivefold higher citric acid level on glycerol as a carbon source compared to its parent strain. It was concluded that the screening of yeast lysine hyperproducer strains could provide a rapid approach to isolate yeast citric acid hyperproducer strains.

Quality changes and shelf-life extension of ready-to-eat fish patties by adding encapsulated citric acid.

PubMed

Bou, Ricard; Claret, Anna; Stamatakis, Antonios; Martínez, Brigitte; Guerrero, Luis

2017-12-01

Citric acid is commonly used as a flavoring and preservative in food and beverages. The effect of adding citric acid directly or encapsulated (each at 1 and 2 g kg -1 ) on the quality and shelf-life of ready-to-eat sea bass patties was evaluated during storage at 4 °C in vacuum skin packaging. Microbial growth and total basic volatile nitrogen were maintained at relatively low levels up to 8 weeks of storage. With respect to oxidative stability, the addition of encapsulated citric acid minimized secondary oxidation values more efficiently than its direct addition, regardless of the concentration. This is in agreement with the decreased fishy odor observed in those patties containing encapsulated citric acid. Accordingly, sensory analysis showed that the addition of encapsulated citric acid at 1 g kg -1 resulted in lower scores in fish aroma compared to that of the control. Sourness is dependent on the amount of citric acid added, regardless of the form (direct or encapsulated). The form of citric acid addition, rather than the amount of citric acid added, caused changes in texture. Therefore, the use of encapsulated citric acid represents a suitable strategy that is of great interest in the seafood industry. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

76 FR 49735 - Citric Acid and Certain Citrate Salts From the People's Republic of China: Partial Rescission of...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-11

... DEPARTMENT OF COMMERCE International Trade Administration [C-570-938] Citric Acid and Certain... citric acid and certain citrate salts (``citric acid'') from the People's Republic of China (``PRC...., Ltd. (``Xinghua''), a producer and exporter of citric acid, timely requested that the Department...

Improved flotation performance of hematite fines using citric acid as a dispersant

NASA Astrophysics Data System (ADS)

Luo, Xi-mei; Yin, Wan-zhong; Sun, Chuan-yao; Wang, Nai-ling; Ma, Ying-qiang; Wang, Yun-fan

2016-10-01

In this study, citric acid was used as a dispersant to improve the flotation performance of hematite fines. The effect and mechanism of citric acid on the reverse flotation of hematite fines were investigated by flotation tests, sedimentation experiments, scanning electron microscopy (SEM), zeta-potential measurements, and X-ray photoelectron spectroscopy (XPS). The results of SEM analysis and flotation tests reveal that a strong heterocoagulation in the form of slime coating or coagulation in hematite fine slurry affects the beneficiation of hematite ores by froth flotation. The addition of a small amount of citric acid (less than 300 g/t) favorably affects the reverse flotation of hematite fines by improving particle dispersion. The results of sedimentation experiments, zeta-potential measurements, and XPS measurements demonstrate that citric acid adsorbs onto hematite and quartz surfaces via hydrogen bonding, thereby reducing the zeta potentials of mineral surfaces, strengthening the electrical double-layer repulsion between mineral particles, and dispersing the pulp particles.

Oxidative degradation stability and hydrogen sulfide removal performance of dual-ligand iron chelate of Fe-EDTA/CA.

PubMed

Miao, Xinmei; Ma, Yiwen; Chen, Zezhi; Gong, Huijuan

2017-09-05

Catalytic oxidation desulfurization using chelated iron catalyst is an effective method to remove H 2 S from various gas streams including biogas. However, the ligand of ethylenediaminetetraacetic acid (EDTA), which is usually adopted to prepare chelated iron catalyst, is liable to be oxidative degraded, and leads to the loss of desulfurization performance. In order to improve the degradation stability of the iron chelate, a series of iron chelates composed of two ligands including citric acid (CA) and EDTA were prepared and the oxidative degradation stability as well as desulfurization performance of these chelated iron catalysts were studied. Results show that the iron chelate of Fe-CA is more stable than Fe-EDTA, while for the desulfurization performance, the situation is converse. For the dual-ligand iron chelates of Fe-EDTA/CA, with the increase of mol ratio of CA to EDTA in the iron chelate solution, the oxidative degradation stability increased while the desulfurization performance decreased. The results of this work showed that Fe-EDTA/CA with a mol ratio of CA:EDTA = 1:1 presents a relative high oxidative degradation stability and an acceptable desulfurization performance with over 90% of H 2 S removal efficiency.

78 FR 64914 - Citric Acid and Certain Citrate Salts From Canada: Final Results of Antidumping Duty...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-30

... DEPARTMENT OF COMMERCE International Trade Administration [A-122-853] Citric Acid and Certain... results of the third administrative review of the antidumping duty order on citric acid and certain...\\ See Citric Acid and Certain Citrate Salts from Canada: Preliminary Results of Antidumping Duty...

Effect of citric acid on the acidification of artificial pepsin solution for metacercariae isolation from fish.

PubMed

Kim, Min-Ki; Pyo, Kyoung-Ho; Hwang, Young-Sang; Chun, Hyang Sook; Park, Ki Hwan; Ko, Seong-Hee; Chai, Jong-Yil; Shin, Eun-Hee

2013-11-15

Artificial digestive solution based on pepsin is essential for collecting metacercariae from fish. To promote the enzymatic reactivity of pepsin, the pH of the solution has to be adjusted to pH 1.0-2.0. Hydrochloride (HCl) is usually used for this purpose, but the use of HCl raises safety concerns. The aim of this work was to address the usefulness of citric acid as an alternative for HCl for the acidification of pepsin solution, and to examine its potential to damage metacercariae during in vitro digestion as compared with HCl. Changes in pH after adding 1-9% of citric acid (m/v) to pepsin solution were compared to a 1% HCl (v/v) addition. Digestion of fish muscle was evaluated by measuring released protein concentrations by spectrophotometry. In addition, survival rates of metacercariae in pepsin solution were determined at different citric acid concentrations and were compared that of with 1% HCl. The present study shows that addition of citric acid reduced the pH of pepsin solutions to the required level. Addition of more than 5% of citric acid resulted in the effective digestion of fish muscle over 3h in vitro, and 5% citric acid was less lethal to metacercariae than 1% HCl in pepsin solution. Pepsin solution containing 5% citric acid had digestive capacity superior to pepsin solution containing 1% HCl after 3h incubation with released protein concentrations of 12.0 ng/ml for 5% citric acid and 9.6 ng/ml for 1% HCl. Accordingly, the present study suggests that the addition of 5% citric acid to pepsin solution is a good alternative to 1% HCl in infection studies because citric acid is a stable at room temperature and has a good safety profile. In addition, we suggest that the use of citric acid enables the preparation of commercial digestive solutions for the detection of microorganisms in fish and other vertebrate muscle tissue. Copyright © 2013 The Authors. Published by Elsevier B.V. All rights reserved.

77 FR 1455 - Citric Acid and Certain Citrate Salts From the People's Republic of China: Extension of Time...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-10

... DEPARTMENT OF COMMERCE International Trade Administration [A-570-937] Citric Acid and Certain... review of the antidumping duty order on citric acid and certain citrate salts (``citric acid'') from the... practicable to complete the preliminary results of the administrative review of citric acid from the PRC...

An investigation into the stability and sterility of citric acid solutions used for cough reflex testing.

PubMed

Falconer, James R; Wu, Zimei; Lau, Hugo; Suen, Joanna; Wang, Lucy; Pottinger, Sarah; Lee, Elaine; Alazawi, Nawar; Kallesen, Molly; Gargiulo, Derryn A; Swift, Simon; Svirskis, Darren

2014-10-01

Citric acid is used in cough reflex testing in clinical and research settings to assess reflexive cough in patients at risk of swallowing disorders. To address a lack of knowledge in this area, this study investigated the stability and sterility of citric acid solutions. Triplicate solutions of citric acid (0.8 M) in isotonic saline were stored at 4 ± 2 °C for up to 28 days and analysed by high-performance liquid chromatography. Microbiological sterility of freshly prepared samples and bulk samples previously used for 2 weeks within the hospital was determined using a pour plate technique. Microbial survival in citric acid was determined by inoculating Staphylococcus aureus, Escherichia coli, or Candida albicans into citric acid solution and monitoring the number of colony-forming units/mL over 40 min. Citric acid solutions remained stable at 4 °C for 28 days (98.4 ± 1.8 % remained). The freshly prepared and clinical samples tested were sterile. However, viability studies revealed that citric acid solution allows for the survival of C. albicans but not for S. aureus or E. coli. The microbial survival study showed that citric acid kills S. aureus and E. coli but has no marked effect on C. albicans after 40 min. Citric acid samples at 0.8 M remained stable over the 4-week testing period, with viable microbial cells absent from samples tested. However, C. albicans has the ability to survive in citric acid solution if inadvertently introduced in practice. For this reason, in clinical and research practice it is suggested to use single-use aliquots prepared aseptically which can be stored for up to 28 days at 4 °C.

Quantitative assessment of citric acid in lemon juice, lime juice, and commercially-available fruit juice products.

PubMed

Penniston, Kristina L; Nakada, Stephen Y; Holmes, Ross P; Assimos, Dean G

2008-03-01

Knowledge of the citric acid content of beverages may be useful in nutrition therapy for calcium urolithiasis, especially among patients with hypocitraturia. Citrate is a naturally-occurring inhibitor of urinary crystallization; achieving therapeutic urinary citrate concentration is one clinical target in the medical management of calcium urolithiasis. When provided as fluids, beverages containing citric acid add to the total volume of urine, reducing its saturation of calcium and other crystals, and may enhance urinary citrate excretion. Information on the citric acid content of fruit juices and commercially-available formulations is not widely known. We evaluated the citric acid concentration of various fruit juices. The citric acid content of 21 commercially-available juices and juice concentrates and the juice of three types of fruits was analyzed using ion chromatography. Lemon juice and lime juice are rich sources of citric acid, containing 1.44 and 1.38 g/oz, respectively. Lemon and lime juice concentrates contain 1.10 and 1.06 g/oz, respectively. The citric acid content of commercially available lemonade and other juice products varies widely, ranging from 0.03 to 0.22 g/oz. Lemon and lime juice, both from the fresh fruit and from juice concentrates, provide more citric acid per liter than ready-to-consume grapefruit juice, ready-to-consume orange juice, and orange juice squeezed from the fruit. Ready-to-consume lemonade formulations and those requiring mixing with water contain < or =6 times the citric acid, on an ounce-for-ounce basis, of lemon and lime juice.

Application of carbon and hydrogen stable isotope analyses to detect exogenous citric acid in Japanese apricot liqueur.

PubMed

Akamatsu, Fumikazu; Oe, Takaaki; Hashiguchi, Tomokazu; Hisatsune, Yuri; Kawao, Takafumi; Fujii, Tsutomu

2017-08-01

Japanese apricot liqueur manufacturers are required to control the quality and authenticity of their liqueur products. Citric acid made from corn is the main acidulant used in commercial liqueurs. In this study, we conducted spiking experiments and carbon and hydrogen stable isotope analyses to detect exogenous citric acid used as an acidulant in Japanese apricot liqueurs. Our results showed that the δ 13 C values detected exogenous citric acid originating from C 4 plants but not from C 3 plants. The δ 2 H values of citric acid decreased as the amount of citric acid added increased, whether the citric acid originated from C 3 or C 4 plants. Commercial liqueurs with declared added acidulant provided higher δ 13 C values and lower δ 2 H values than did authentic liqueurs and commercial liqueurs with no declared added acidulant. Carbon and hydrogen stable isotope analyses are suitable as routine methods for detecting exogenous citric acid in Japanese apricot liqueur. Copyright © 2017 Elsevier Ltd. All rights reserved.

77 FR 22560 - Citric Acid and Certain Citrate Salts From the People's Republic of China: Extension of Time...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-16

... DEPARTMENT OF COMMERCE International Trade Administration [A-570-937] Citric Acid and Certain... review of the antidumping duty order on citric acid and certain citrate salts (``citric acid'') from the... Request for Revocation in Part, 76 FR 37781, 37785 (June 28, 2011). \\2\\ See Citric Acid and Certain...

Crosslinking of agarose bioplastic using citric acid.

PubMed

Awadhiya, Ankur; Kumar, David; Verma, Vivek

2016-10-20

We report chemical crosslinking of agarose bioplastic using citric acid. Crosslinking was confirmed using Fourier transform infrared (FTIR) spectroscopy. The effects of crosslinking on the tensile strength, swelling, thermal stability, and degradability of the bioplastic were studied in detail. The tensile strength of the bioplastic films increased from 25.1MPa for control films up to a maximum of 52.7MPa for citric acid crosslinked films. At 37°C, the amount of water absorbed by crosslinked agarose bioplastic was only 11.5% of the amount absorbed by non-crosslinked controls. Thermogravimetric results showed that the crosslinked samples retain greater mass at high temperature (>450°C) than control samples. Moreover, while the crosslinked films were completely degradable, the rate of degradation was lower compared to non-crosslinked controls. Copyright © 2016 Elsevier Ltd. All rights reserved.

The impact of harmfulness information on citric acid induced cough and urge-to-cough.

PubMed

Janssens, Thomas; Brepoels, Sarah; Dupont, Lieven; Van den Bergh, Omer

2015-04-01

The cough reflex is an automatic protective reflex, which can be modulated by conscious effort or other forms of top-down control. In this experiment, we investigated whether information about harmfulness of a cough-inducing substance would augment cough reflex sensitivity and associated urge-to-cough. Healthy participants (N = 39) were randomized to receive information that they were to inhale a harmless substance (natural citric acid), or a potentially harmful substance (a potent agro-chemical acid). Using dosimeter-controlled inhalations, the dose of citric acid eliciting at least three coughs (C3) was determined. Next, participants received 4 blocks of randomized presentations of citric acid at the C3 dose, a sub-threshold dose of citric acid and saline control. C3 was reached for 27/39 participants, and C3 thresholds were not influenced by harmfulness information. During repeated citric acid presentations, framing the cough-inducing substance as a potentially harmful chemical resulted in a greater urge-to-cough compared to information framing it as natural citric acid (p < .01). The experimental manipulation did not influence cough frequencies. Our findings show that harmfulness information influences urge-to-cough, corroborating the role of cortical mechanisms in modulating the urge-to-cough and suggesting that cognitive manipulations may contribute to cough treatment. Copyright © 2015 Elsevier Ltd. All rights reserved.

Exogenous Application of Citric Acid Ameliorates the Adverse Effect of Heat Stress in Tall Fescue (Lolium arundinaceum)

PubMed Central

Hu, Longxing; Zhang, Zhifei; Xiang, Zuoxiang; Yang, Zhijian

2016-01-01

Citric acid may be involved in plant response to high temperature. The objective of this study was to investigate whether exogenous citric acid could improve heat tolerance in a cool-season turfgrass species, tall fescue (Lolium arundinaceum), and to determine the physiological mechanisms of citric acid effects on heat stress tolerance. The grasses were subjected to four citric acid levels (0, 0.2, 2, and 20 mM) and two temperature levels (25/20 and 35/30 ± 0.5°C, day/night) treatments in growth chambers. Heat stress increased an electrolyte leakage (EL) and malonaldehyde (MDA) content, while reduced plant growth, chlorophyll (Chl) content, photochemical efficiency (Fv/Fm), root activity and antioxidant enzyme activities (superoxide dismutase, SOD; catalase, CAT; peroxidase, POD). External citric acid alleviated the detrimental effects of heat stress on tall fescue, which was evidenced by decreased EL and MDA content, and improved plant growth under stress conditions. Additionally, the reduction in Chl content, Fv/Fm, SOD, POD, CAT and root activity were ameliorated in citric acid treated plants under heat stressed conditions. High temperature induced the expression of heat shock protein (HSP) genes, which exhibited greater expression levels after citric acid treatment under heat stress. These results suggest that exogenous citric acid application may alleviate growth and physiological damage caused by high temperature. In addition, the exogenously applied citric acid might be responsible for maintaining membrane stability, root activity, and activation of antioxidant response and HSP genes which could contribute to the protective roles of citric acid in tall fescue responses to heat stress. PMID:26925085

Detection and formation scenario of citric acid, pyruvic acid, and other possible metabolism precursors in carbonaceous meteorites

PubMed Central

Cooper, George; Reed, Chris; Nguyen, Dang; Carter, Malika; Wang, Yi

2011-01-01

Carbonaceous meteorites deliver a variety of organic compounds to Earth that may have played a role in the origin and/or evolution of biochemical pathways. Some apparently ancient and critical metabolic processes require several compounds, some of which are relatively labile such as keto acids. Therefore, a prebiotic setting for any such individual process would have required either a continuous distant source for the entire suite of intact precursor molecules and/or an energetic and compact local synthesis, particularly of the more fragile members. To date, compounds such as pyruvic acid, oxaloacetic acid, citric acid, isocitric acid, and α-ketoglutaric acid (all members of the citric acid cycle) have not been identified in extraterrestrial sources or, as a group, as part of a “one pot” suite of compounds synthesized under plausibly prebiotic conditions. We have identified these compounds and others in carbonaceous meteorites and/or as low temperature (laboratory) reaction products of pyruvic acid. In meteorites, we observe many as part of three newly reported classes of compounds: keto acids (pyruvic acid and homologs), hydroxy tricarboxylic acids (citric acid and homologs), and tricarboxylic acids. Laboratory syntheses using 13C-labeled reactants demonstrate that one compound alone, pyruvic acid, can produce several (nonenzymatic) members of the citric acid cycle including oxaloacetic acid. The isotopic composition of some of the meteoritic keto acids points to interstellar or presolar origins, indicating that such compounds might also exist in other planetary systems. PMID:21825143

Detection and formation scenario of citric acid, pyruvic acid, and other possible metabolism precursors in carbonaceous meteorites.

PubMed

Cooper, George; Reed, Chris; Nguyen, Dang; Carter, Malika; Wang, Yi

2011-08-23

Carbonaceous meteorites deliver a variety of organic compounds to Earth that may have played a role in the origin and/or evolution of biochemical pathways. Some apparently ancient and critical metabolic processes require several compounds, some of which are relatively labile such as keto acids. Therefore, a prebiotic setting for any such individual process would have required either a continuous distant source for the entire suite of intact precursor molecules and/or an energetic and compact local synthesis, particularly of the more fragile members. To date, compounds such as pyruvic acid, oxaloacetic acid, citric acid, isocitric acid, and α-ketoglutaric acid (all members of the citric acid cycle) have not been identified in extraterrestrial sources or, as a group, as part of a "one pot" suite of compounds synthesized under plausibly prebiotic conditions. We have identified these compounds and others in carbonaceous meteorites and/or as low temperature (laboratory) reaction products of pyruvic acid. In meteorites, we observe many as part of three newly reported classes of compounds: keto acids (pyruvic acid and homologs), hydroxy tricarboxylic acids (citric acid and homologs), and tricarboxylic acids. Laboratory syntheses using (13)C-labeled reactants demonstrate that one compound alone, pyruvic acid, can produce several (nonenzymatic) members of the citric acid cycle including oxaloacetic acid. The isotopic composition of some of the meteoritic keto acids points to interstellar or presolar origins, indicating that such compounds might also exist in other planetary systems.

Citric acid production in Yarrowia lipolytica SWJ-1b yeast when grown on waste cooking oil.

PubMed

Liu, Xiaoyan; Lv, Jinshun; Xu, Jiaxing; Zhang, Tong; Deng, Yuanfang; He, Jianlong

2015-03-01

In this study, citric acid was produced from waste cooking oil by Yarrowia lipolytica SWJ-1b. To get the maximal yield of citric acid, the compositions of the medium for citric acid production were optimized, and our results showed that extra nitrogen and magnesium rather than vitamin B1 and phosphate were needed for CA accumulation when using waste cooking oil. The results also indicated that the optimal initial concentration of the waste cooking oil in the medium for citric acid production was 80.0 g/l, and the ideal inoculation size was 1 × 10(7) cells/l of medium. We also reported that during 10-l fermentation, 31.7 g/l of citric acid, 6.5 g/l of isocitric acid, 5.9 g/l of biomass, and 42.1 g/100.0 g cell dry weight of lipid were attained from 80.0 g/l of waste cooking oil within 336 h. At the end of the fermentation, 94.6 % of the waste cooking oil was utilized by the cells of Y. lipolytica SWJ-1b, and the yield of citric acid was 0.4 g/g waste cooking oil, which suggested that waste cooking oil was a suitable carbon resource for citric acid production.

Use of Energy Crop (Ricinus communis L.) for Phytoextraction of Heavy Metals Assisted with Citric Acid.

PubMed

Zhang, Hui; Chen, Xueping; He, Chiquan; Liang, Xia; Oh, Kokyo; Liu, Xiaoyan; Lei, Yanru

2015-01-01

Ricinus communis L. is a bioenergetic crop with high-biomass production and tolerance to cadmium (Cd) and lead (Pb), thus, the plant is a candidate crop for phytoremediation. Pot experiments were performed to study the effects of citric acid in enhancing phytoextraction of Cd/Pb by Ricinus communis L. Citric acid increased Cd and Pb contents in plant shoots in all treatments by about 78% and 18-45%, respectively, at the dosage of 10 mM kg(-1) soil without affecting aboveground biomass production. Addition of citric acid reduced CEC, weakened soil adsorption of heavy metals and activated Cd and Pb in soil solutions. The acid-exchangeable fraction (BCR-1) of Pb remained lower than 7% and significantly increased with citric acid amendment. Respective increases in soil evaluation index induces by 14% and 19% under the Cd1Pb50 and Cd1Pb250 treatments upon addition of citric acid resulted in soil quality improvement. Ricinus communis L. has great potential in citric acid-assisted phytoextraction for Cd and Pb remediation.

Metabolic interaction between urea cycle and citric acid cycle shunt: A guided approach.

PubMed

Pesi, Rossana; Balestri, Francesco; Ipata, Piero L

2018-03-01

This article is a guided pedagogical approach, devoted to postgraduate students specializing in biochemistry, aimed at presenting all single reactions and overall equations leading to the metabolic interaction between ureagenesis and citric acid cycle to be incorporated into a two-three lecture series about the interaction of urea cycle with other metabolic pathways. We emphasize that citrate synthetase, aconitase, and isocitrate dehydrogenase, three enzymes of the citric acid cycle are not involved, thus creating a shunt in citric acid cycle. In contrast, the glutamic-oxaloacetate transaminase, which does not belong to citric acid cycle, has a paramount importance in the metabolic interaction of the two cycles, because it generates aspartate, one of the two fuel molecules of urea cycle, and a-ketoglutarate, an intermediate of the citric acid cycle. Finally, students should appreciate that balancing equations for all atoms and charges is not only a stoichiometric task, but strongly facilitates the discussion of the physiological roles of metabolic pathways. Indeed, this exercise has been used in the classroom, to encourage a deeper level of understanding of an important biochemical issue. © 2017 by The International Union of Biochemistry and Molecular Biology, 46(2):182-185, 2018. © 2017 The International Union of Biochemistry and Molecular Biology.

Scanning Electron Microscopic Evaluation of Root Canal Irrigation with Saline, Sodium Hypochlorite, and Citric Acid,

DTIC Science & Technology

1983-12-01

with six different irrigation regimens. Sodium hypochlorite (NaOCl) was significantly more effective than citric acid in "* removing superficial...EVALUATION OF ROOT CANAL IRRIGATION WITH SALINE, SODIUM HYPOCHLORITE , AND CITRIC ACID 4 *J. Craig Baumgartner, D.D.S., M.S. • **Carolyn M. Brown, D.D.S., M.S...preparation with six different irrigation regimens. Sodium hypochlorite (NaOCl) was significantly more effective than citric acid in removing superficial

Modification of rat detrusor muscle contraction by ascorbic acid and citric acid involving enhanced neurotransmitter release and Ca2+ influx.

PubMed

Dasgupta, Jaydip; Elliott, Ruth A; Tincello, Douglas G

2009-01-01

Consumption of carbonated soft drinks is independently associated with the development of overactive bladder (OR 1.41, 95% Cl 1.02-1.95). We have shown previously that artificial sweeteners, present in carbonated soft drinks, enhanced detrusor muscle contraction. Other constituents of soft drinks are preservatives and antioxidants, we evaluated the effects of two of these, ascorbic acid and citric acid, on the contractile response of isolated rat bladder muscle strips. Detrusor muscle strips were suspended in a perfusion organ bath. We determined the effect of ascorbic acid and citric acid on the contractile responses to electrical field stimulation (EFS) in the absence and presence of atropine, carbachol, alpha, beta methylene ATP, potassium and calcium. Ascorbic acid and citric acid (10(-7) M to 10(-3) M) enhanced the contractile response to 10 Hz EFS compared to control (P < 0.01). The frequency and amplitude of spontaneous bladder contractions were enhanced in the presence of ascorbic acid and citric acid by 14%, 21%, 21%, and 11% respectively. Ascorbic acid 10(-4) M significantly increased the atropine resistant response to EFS 5 Hz by 37% (P < 0.01) and inhibited contraction in response to carbachol 10(-4) M by 24%, (P < 0.05). Both ascorbic acid 10(-4) M and citric acid 10(-5) M significantly enhanced maximum contractile responses to alpha, beta methylene ATP, KCI and calcium compared to control. Ascorbic acid and citric acid augmented bladder muscle contraction possibly by enhanced Ca(2+) influx. Presynaptic neurotransmitter release was enhanced by ascorbic acid. Carbonated beverages containing preservatives may aggravate symptoms of OAB. (c) 2009 Wiley-Liss, Inc.

Preparation and physico-chemical properties of hydrogels from carboxymethyl cassava starch crosslinked with citric acid

NASA Astrophysics Data System (ADS)

Boonkham, Sasikan; Sangseethong, Kunruedee; Chatakanon, Pathama; Niamnuy, Chalida; Nakasaki, Kiyohiko; Sriroth, Klanarong

2014-06-01

Recently, environmentally friendly hydrogels prepared from renewable bio-based resources have drawn significant attention from both industrial and academic sectors. In this study, chemically crosslinked hydrogels have been developed from cassava starch which is a bio-based polymer using a non-toxic citric acid as a crosslinking agent. Cassava starch was first modified by carboxymethylation to improve its water absorbency property. The carboxymethyl cassava starch (CMCS) obtained was then crosslinked with citric acid at different concentrations and reaction times. The gel fraction of hydrogels increased progressively with increasing citric acid concentration. Free swelling capacity of hydrogels in de-ionized water, saline solution and buffers at various pHs as well as absorption under load were investigated. The results revealed that swelling behavior and mechanical characteristic of hydrogels depended on the citric acid concentration used in reaction. Increasing citric acid concentration resulted in hydrogels with stronger network but lower swelling and absorption capacity. The cassava starch hydrogels developed were sensitive to ionic strength and pH of surrounding medium, showing much reduced swelling capacity in saline salt solution and acidic buffers.

Optimization of date syrup for enhancement of the production of citric acid using immobilized cells of Aspergillus niger

PubMed Central

Mostafa, Yasser S.; Alamri, Saad A.

2012-01-01

Date syrup as an economical source of carbohydrates and immobilized Aspergillus niger J4, which was entrapped in calcium alginate pellets, were employed for enhancing the production of citric acid. Maximum production was achieved by pre-treating date syrup with 1.5% tricalcium phosphate to remove heavy metals. The production of citric acid using a pretreated medium was 38.87% higher than an untreated one that consumed sugar. The appropriate presence of nitrogen, phosphate and magnesium appeared to be important in order for citric acid to accumulate. The production of citric acid and the consumed sugar was higher when using 0.1% ammonium nitrate as the best source of nitrogen. The production of citric acid increased significantly when 0.1 g/l of KH2PO4 was added to the medium of date syrup. The addition of magnesium sulfate at the rate of 0.20 g/l had a stimulating effect on the production of citric acid. Maximum production of citric acid was obtained when calcium chloride was absent. One of the most important benefits of immobilized cells is their ability and stability to produce citric acid under a repeated batch culture. Over four repeated batches, the production of citric acid production was maintained for 24 days when each cycle continued for 144 h. The results obtained in the repeated batch cultivation using date syrup confirmed that date syrup could be used as a medium for the industrial production of citric acid. PMID:23961184

Sodium Picosulfate, Magnesium Oxide, and Anhydrous Citric Acid

MedlinePlus

Sodium picosulfate, magnesium oxide, and anhydrous citric acid combination powder is used to empty the colon (large ... clear view of the walls of the colon. Sodium picosulfate is in a class of medications called ...

Citric Acid-Modified Fenton's Reaction for the Oxidation of Chlorinated Ethylenes in Soil Solution Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seol, Yongkoo; Javandel, Iraj

Fenton's reagent, a solution of hydrogen peroxide and ferrous iron catalyst, is used for an in-situ chemical oxidation of organic contaminants. Sulfuric acid is commonly used to create an acidic condition needed for catalytic oxidation. Fenton's reaction often involves pressure buildup and precipitation of reaction products, which can cause safety hazards and diminish efficiency. We selected citric acid, a food-grade substance, as an acidifying agent to evaluate its efficiencies for organic contaminant removal in Fenton's reaction, and examined the impacts of using citric acid on the unwanted reaction products. A series of batch and column experiments were performed with varyingmore » H{sub 2}O{sub 2} concentrations to decompose selected chlorinated ethylenes. Either dissolved iron from soil or iron sulfate salt was added to provide the iron catalyst in the batch tests. Batch experiments revealed that both citric and sulfuric acid systems achieved over 90% contaminant removal rates, and the presence of iron catalyst was essential for effective decontamination. Batch tests with citric acid showed no signs of pressure accumulation and solid precipitations, however the results suggested that an excessive usage of H{sub 2}O{sub 2} relative to iron catalysts (Fe{sup 2+}/H{sub 2}O{sub 2} < 1/330) would result in lowering the efficiency of contaminant removal by iron chelations in the citric acid system. Column tests confirmed that citric acid could provide suitable acidic conditions to achieve higher than 55% contaminant removal rates.« less

Citric acid-modified Fenton's reaction for the oxidation of chlorinated ethylenes in soil solution systems.

PubMed

Seol, Yongkoo; Javandel, Iraj

2008-06-01

Fenton's reagent, a solution of hydrogen peroxide and ferrous iron catalyst, is used for an in situ chemical oxidation of organic contaminants. Sulfuric acid is commonly used to create an acidic condition needed for catalytic oxidation. Fenton's reaction often involves pressure buildup and precipitation of reaction products, which can cause safety hazards and diminish efficiency. We selected citric acid, a food-grade substance, as an acidifying agent to evaluate its efficiencies for organic contaminant removal in Fenton's reaction, and examined the impacts of using citric acid on the unwanted reaction products. A series of batch and column experiments were performed with varying H2O2 concentrations to decompose selected chlorinated ethylenes. Either dissolved iron from soil or iron sulfate salt was added to provide the iron catalyst in the batch tests. Batch experiments revealed that both citric and sulfuric acid systems achieved over 90% contaminant removal rates, and the presence of iron catalyst was essential for effective decontamination. Batch tests with citric acid showed no signs of pressure accumulation and solid precipitations, however the results suggested that an excessive usage of H2O2 relative to iron catalysts (Fe2+/H2O2<1/330) would result in lowering the efficiency of contaminant removal by iron chelation in the citric acid system. Column tests confirmed that citric acid could provide suitable acidic conditions to achieve higher than 55% contaminant removal rates.

The Effect of Citric Acid on the Oxidation of Organic Contaminants by Fenton's Reagent

NASA Astrophysics Data System (ADS)

Seol, Y.; Javandel, I.; Lee, G.

2003-12-01

Combined with acids and iron catalysts, hydrogen peroxide (H2O2) as Fenton's reagent is proven to be effective in oxidizing halogenated volatile organic compounds (VOCs). The Fenton's reagent, traditionally used for waste water treatment technique, has been applied to the remediation of contaminated soil systems and numerous investigators have found intrinsic iron salts are effective source of iron catalyst for the reaction. Citric acid, which is naturally occurring nutrients to microorganisms and less destructive to soil chemical properties, is selected for an acidifying agent to create acidic soil condition. However, citric acid has been considered as a reaction inhibitant because it sequesters ferric iron from Fenton's catalytic cycle by forming strong chelates with iron. This paper presents the feasibility of using citric acid as an acidifying agent of soil matrix for the Fenton-like oxidation. Series of batch tests were performed to test disappearance of VOCs in various aqueous systems with two acidifying agents (citric acid or sulfuric acid) and three iron sources (iron sulfate, water soluble soil iron, or soil matrix). Batch results show that soluble iron is essential for near complete disappearance of VOCs and that citric acid performs similarly to sulfuric acid at low H2O2 dosage (< 1 wt%). The test soil provided water-soluble soil iron but also contained scavengers of the oxidizing agents, resulting in limited removals of VOCs. Column tests confirmed the results of the batch tests, suggesting citric acid is also as effective as sulfuric acid in providing acidic environment for the Fenton-like oxidation. The batch experiments also reveal that higher doses of H2O2 lower the degree of VOC removals in citric acid systems. Potential explanations for this declining include that excessive presence of H2O2 expedites the oxidation of ferrous to ferric iron, which then forms a strong complex with citrate, leading to the sequestration of the iron from the Fenton

Effect of citric acid on setting reaction and tissue response to β-TCP granular cement.

PubMed

Fukuda, Naoyuki; Tsuru, Kanji; Mori, Yoshihide; Ishikawa, Kunio

2017-02-24

We recently reported that when an acidic calcium phosphate solution is mixed with β-tricalcium phosphate (β-TCP) granules, the resulting dicalcium phosphate dihydrate (DCPD) crystals form bridges between the β-TCP granules, creating a set interconnected porous structure in approximately 1 min. Although this self-setting β-TCP granular cement (β-TCPGC) is useful for clinical applications, the short setting time is a key drawback for handling. In this study, the setting time of β-TCPGC was adjusted with the addition of citric acid, which is a known inhibiter of DCPD crystal growth. As the concentration of citric acid in the acidic calcium phosphate solution increased, the amount of DCPD formation in the set β-TCPGC decreased, and the crystal morphology of DCPD became elongated. β-TCPGC prepared with various citric acid concentrations were used as grafting material in rat calvarial bone defects to evaluate bone regeneration in vivo. Four weeks after implantation, no inflammatory reaction and approximately 20% new bone formation were observed, regardless of the presence or absence of citric acid in the liquid phase of β-TCPGC. We concluded, therefore, that citric acid might be a useful retarder of β-TCPGC setting times.

Changes in the physiological properties and kinetics of citric acid accumulation via carbon ion irradiation mutagenesis of Aspergillus niger *

PubMed Central

Hu, Wei; Chen, Ji-hong; Wang, Shu-yang; Liu, Jing; Song, Yuan; Wu, Qing-feng; Li, Wen-jian

2016-01-01

The objective of this work was to produce citric acid from corn starch using a newly isolated mutant of Aspergillus niger, and to analyze the relationship between changes in the physiological properties of A. niger induced by carbon ion irradiation and citric acid accumulation. Our results showed that the physiological characteristics of conidia in A. niger were closely related to citric acid accumulation and that lower growth rate and viability of conidia may be beneficial to citric acid accumulation. Using corn starch as a raw material, a high-yielding citric acid mutant, named HW2, was obtained. In a 10-L bioreactor, HW2 can accumulate 118.9 g/L citric acid with a residual total sugar concentration of only 14.4 g/L. This represented an 18% increase in citric acid accumulation and a 12.5% decrease in sugar utilization compared with the original strain.

Evaluating EDTA as a substitute for phosphoric acid-etching of enamel and dentin.

PubMed

Imbery, Terence A; Kennedy, Matthew; Janus, Charles; Moon, Peter C

2012-01-01

Matrix metalloproteinases (MMPs) are proteolytic enzymes released when dentin is acid-etched. The enzymes are capable of destroying unprotected collagen fibrils that are not encapsulated by the dentin adhesive. Chlorhexidine applied after etching inhibits the activation of released MMPs, whereas neutral ethylenediamine tetra-acetic acid (EDTA) prevents the release of MMPs. The purpose of this study was to determine if conditioning enamel and dentin with EDTA can be a substitute for treating acid-etching enamel and dentin with chlorhexidine. A column of composite resin was bonded to enamel and dentin after conditioning. Shear bond strengths were evaluated after 48 hours and after accelerated aging for three hours in 12% sodium hypochlorite. Shear bond strengths ranged from 15.6 MP a for accelerated aged EDTA enamel specimens to 26.8 MPa for dentin conditioned with EDTA and tested after 48 hours. A three-way ANOVA and a Tukey HSD test found statistically significant differences among the eight groups and the three independent variables (P < 0.05). EDTA was successfully substituted for phosphoric acid-etched enamel and dentin treated with chlorhexidine. Interactions of conditioning agent and aging were significant for dentin but not for enamel. In an effort to reduce the detrimental effects of MMPs, conditioning enamel and dentin with EDTA is an alternative to treating acid-etched dentin and enamel with chlorhexidine.

Effect of Ginger Extract and Citric Acid on the Tenderness of Duck Breast Muscles

PubMed Central

2015-01-01

The objective of this study was to examine the effect of ginger extract (GE) combined with citric acid on the tenderness of duck breast muscles. Total six marinades were prepared with the combination of citric acid (0 and 0.3 M citric acid) and GE (0, 15, and 30%). Each marinade was sprayed on the surface of duck breasts (15 mL/100 g), and the samples were marinated for 72 h at 4℃. The pH and proteolytic activity of marinades were determined. After 72 h of marination, Warner Bratzler shear force (WBSF), myofibrillar fragmentation index (MFI), pH, cooking loss, moisture content, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and protein solubility were evaluated. There was no significant (p>0.05) difference in moisture content or cooking loss among all samples. However, GE marination resulted in a significant (p<0.05) decrease in WBSF but a significant (p<0.05) increase in pH and MFI. In addition, total protein and myofibrillar protein solubility of GE-marinated duck breast muscles in both WOC (without citric acid) and WC (with citric acid) conditions were significantly (p<0.05) increased compared to non-GE-marinated duck breast muscles. SDS-PAGE showed an increase of protein degradation (MHC and actin) in WC condition compared to WOC condition. There was a marked actin reduction in GE-treated samples in WC. The tenderization effect of GE combined with citric acid may be attributed to various mechanisms such as increased MFI and myofibrillar protein solubility. PMID:26877631

Simultaneous saccharification and aerobic fermentation of high titer cellulosic citric acid by filamentous fungus Aspergillus niger.

PubMed

Hou, Weiliang; Bao, Jie

2018-04-01

Simultaneous saccharification and fermentation (SSF) is the most efficient operation in biorefining conversion, but aerobic SSF under high solids loading significantly faces the serious oxygen transfer limitation. This study took the first insight into an aerobic SSF by high oxygen demanding filamentous fungi in highly viscous lignocellulose hydrolysate. The results show that oxygen requirement in the aerobic SSF by Aspergillus niger was well satisfied for production of cellulosic citric acid. The record high citric acid titer of 136.3 g/L and the overall conversion yield of 74.9% of cellulose were obtained by the aerobic SSF. The advantage of SSF to the separate hydrolysis and fermentation (SHF) on citric acid fermentation was compared based on the rigorous Aspen Plus modeling. The techno-economic analysis indicates that the minimum citric acid selling price (MCSP) of $0.603 per kilogram by SSF was highly competitive with the commercial citric acid from starch feedstock. Copyright © 2018 Elsevier Ltd. All rights reserved.

Potential citric acid exposure and toxicity to Hawaiian hoary bats (Lasiurus cinereus semotus) associated with Eleutherodactylus frog control.

PubMed

Pitt, William C; Witmer, Gary W; Jojola, Susan M; Sin, Hans

2014-04-01

We examined potential exposure of Hawaiian hoary bats (Lasiurus cinereus semotus) to citric acid, a minimum risk pesticide registered for control of invasive Eleutherodactylus frog populations. Hoary bats are nocturnal insectivores that roost solitarily in foliage, federally listed as endangered, and are endemic to Hawaii. Oral ingestion during grooming of contaminated fur appears to be the principal route by which these bats might be exposed to citric acid. We made assessments of oral toxicity, citric acid consumption, retention of material on fur, and grooming using big brown bats (Eptesicus fuscus) as a surrogate species. We evaluated both ground application and aerial application of 16 % solutions of citric acid during frog control operations. Absorbent bat effigies exposed to ground and aerial operational spray applications retained means of 1.54 and 0.02 g, respectively, of dry citric acid, although retention by the effigies was much higher than bat carcasses drenched in citric acid solutions. A high dose delivered orally (2,811 mg/kg) was toxic to the big brown bats and emesis occurred in 1 bat dosed as low as the 759 mg/kg level. No effect was observed with the lower doses examined (≤ 542 mg/kg). Bats sprayed with 5 ml of 16 % (w/w) citric acid solution showed no evidence of intoxication. In field situations, it is unlikely that bats would be sprayed directly or ingest much citric acid retained by fur. Based on our observations, we believe Hawaiian hoary bats to be at very low risk from harmful exposure to a toxic dose of citric acid during frog control operations.

76 FR 17835 - Citric Acid and Certain Citrate Salts From the People's Republic of China: Extension of Time...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-03-31

... DEPARTMENT OF COMMERCE International Trade Administration A-570-937] Citric Acid and Certain... initiation of the administrative review of the antidumping duty order on citric acid and certain citrate salts (``citric acid'') from the People's Republic of China (``PRC''). See Initiation of Antidumping and...

76 FR 56158 - Citric Acid and Certain Citrate Salts From the People's Republic of China: Extension of Time...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-12

... DEPARTMENT OF COMMERCE International Trade Administration [C-570-938] Citric Acid and Certain... preliminary results of the administrative review of the countervailing duty order on citric acid and certain..., 2009. See Citric Acid and Certain Citrate Sales from the People's Republic of China: Preliminary...

76 FR 82275 - Citric Acid and Certain Citrate Salts From the People's Republic of China: Extension of Time...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-12-30

... DEPARTMENT OF COMMERCE International Trade Administration [C-570-938] Citric Acid and Certain...) published in the Federal Register the countervailing duty order on citric acid and certain citrate salts... Affirmative Countervailing Duty Determinations: Citric Acid and Certain Citrate Salts, 74 FR 25705 (May 29...

Effects of tempering (annealing), acid hydrolysis, low-citric acid substitution on chemical and physicochemical properties of starches of four yam (Dioscorea spp.) cultivars.

PubMed

Falade, Kolawole O; Ayetigbo, Oluwatoyin E

2017-05-01

The effects of tempering (annealing), acid hydrolysis and low-citric acid substitution on chemical and physicochemical properties of starches of four Nigerian yam cultivars were investigated. Crude fat and protein contents of the native starches decreased significantly after the modifications, while nitrogen-free extract increased significantly with acid hydrolysis and citric acid substitution. Acid hydrolysis and low-citric acid substitution reduced the least concentration for gel formation of the starches from 4 to 2% w/v, but tempering had no effect. Swelling power of the starches reduced significantly, and water solubility increased significantly at 75 and 85 °C, especially with acid hydrolysis and low-citric acid substitution. However, tempering significantly reduced starch solubility in the four cultivars. Paste clarity of starches of white (29.17%), water (18.90%), yellow (30.90%) and bitter (10.57%) yams reduced significantly with tempering to 14.43, 11.83, 16.93 and 7.27%, but increased significantly with acid hydrolysis to 41.40, 35.37, 28.77 and 32.33%, and low-citric acid substitution to 36.60, 44.17, 50.67 and 14.33%, respectively. Pasting properties such as peak, trough, breakdown, final, and setback viscosities and peak time of native starches reduced significantly with acid hydrolysis and low-citric acid substitution, however, tempering significantly increased their pasting temperature, peak time, setback and final viscosities.

77 FR 9891 - Citric Acid and Certain Citrate Salts from the People's Republic of China: Amended Final Results...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-21

... DEPARTMENT OF COMMERCE International Trade Administration [A-570-937] Citric Acid and Certain... the final results of the first administrative review of the antidumping duty order on citric acid and certain citrate salts (``citric acid'') from the People's Republic of China (``PRC'').\\1\\ The period of...

77 FR 56188 - Citric Acid and Certain Citrate Salts from the People's Republic of China: Notice of Rescission...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-12

... the order includes all grades and granulation sizes of citric acid, sodium citrate, and potassium... also includes blends of citric acid, sodium citrate, and potassium citrate; as well as blends with other ingredients, such as sugar, where the unblended form(s) of citric acid, sodium citrate, and...

Overexpression of the NADP+-specific isocitrate dehydrogenase gene (icdA) in citric acid-producing Aspergillus niger WU-2223L.

PubMed

Kobayashi, Keiichi; Hattori, Takasumi; Hayashi, Rie; Kirimura, Kohtaro

2014-01-01

In the tricarboxylic acid (TCA) cycle, NADP(+)-specific isocitrate dehydrogenase (NADP(+)-ICDH) catalyzes oxidative decarboxylation of isocitric acid to form α-ketoglutaric acid with NADP(+) as a cofactor. We constructed an NADP(+)-ICDH gene (icdA)-overexpressing strain (OPI-1) using Aspergillus niger WU-2223L as a host and examined the effects of increase in NADP(+)-ICDH activity on citric acid production. Under citric acid-producing conditions with glucose as the carbon source, the amounts of citric acid produced and glucose consumed by OPI-1 for the 12-d cultivation period decreased by 18.7 and 10.5%, respectively, compared with those by WU-2223L. These results indicate that the amount of citric acid produced by A. niger can be altered with the NADP(+)-ICDH activity. Therefore, NADP(+)-ICDH is an important regulator of citric acid production in the TCA cycle of A. niger. Thus, we propose that the icdA gene is a potentially valuable tool for modulating citric acid production by metabolic engineering.

Effect of citric acid modification of aspen wood on sorption of copper ion

Treesearch

James D. McSweeny; Roger M. Rowell; Soo Hong Min

2006-01-01

Milled aspen wood was thermochemically modified with citric acid for the purpose of improving the copper (Cu2+) ion sorption capacity of the wood when tested in 24-hour equilibrium batch tests. The wood-citric acid adducts provided additional carboxyl groups to those in the native wood and substantially increased Cu2+ ion uptake of the modified wood compared with that...

77 FR 72323 - Citric Acid and Certain Citrate Salts From the People's Republic of China: Final Results of...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-05

... DEPARTMENT OF COMMERCE International Trade Administration [C-570-938] Citric Acid and Certain... countervailing duty (CVD) order on citric acid and certain citrate salts from the People's Republic of China for... results of this review.\\1\\ \\1\\ See Citric Acid and Certain Citrate Salts from the People's Republic of...

77 FR 47370 - Citric Acid and Certain Citrate Salts from the People's Republic of China: Intent To Rescind...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-08

... order includes all grades and granulation sizes of citric acid, sodium citrate, and potassium citrate in... includes blends of citric acid, sodium citrate, and potassium citrate; as well as blends with other ingredients, such as sugar, where the unblended form(s) of citric acid, sodium citrate, and potassium citrate...

Enhanced concentrations of citric acid in spring aerosols collected at the Gosan background site in East Asia

NASA Astrophysics Data System (ADS)

Jung, Jinsang; Kawamura, Kimitaka

2011-09-01

In order to investigate water-soluble dicarboxylic acids and related compounds in the aerosol samples under the Asian continent outflow, total suspended particle (TSP) samples ( n = 32) were collected at the Gosan site in Jeju Island over 2-5 days integration during 23 March-1 June 2007 and 16-24 April 2008. The samples were analyzed for water-soluble dicarboxylic acids, ketocarboxylic acids, and α-dicarbonyls using a capillary gas chromatography technique. We found elevated concentrations of atmospheric citric acid (range: 20-320 ng m -3) in the TSP samples during mid- to late April of 2007 and 2008. To specify the sources of citric acid, dicarboxylic acids and related compounds were measured in the pollen sample collected at the Gosan site (Pollen_Gosan), authentic pollen samples from Japanese cedar ( Cryptomeria) (Pollen_cedar) and Japanese cypress ( Chamaecyparis obtusa) (Pollen_cypress), and tangerine fruit produced from Jeju Island. Citric acid (2790 ng in unit mg of pollen mass) was found as most abundant species in the Pollen_Gosan, followed by oxalic acid (2390 ng mg -1). Although citric acid was not detected in the Pollen_cedar and Pollen_cypress as major species, it was found as a dominant species in the tangerine juice while malic acid was detected as major species in the tangerine peel, followed by oxalic and citric acids. Since Japanese cedar trees are planted around tangerine farms to prevent strong winds from the Pacific Ocean, citric acid that may be directly emitted from tangerine is likely adsorbed on pollens emitted from Japanese cedar and then transported to the Gosan site. Much lower malic/citric acid ratios obtained under cloudy condition than clear condition suggest that malic acid may rapidly decompose to lower molecular weight compounds such as oxalic and malonic acids (

Synthesis of SrFe12O19 magnetic nanoparticles by EDTA complex method

NASA Astrophysics Data System (ADS)

Wang, Shifa; Li, Danming; Xiao, Yuhua; Dang, Wenqiang; Feng, Jie

2017-10-01

A modified polyacrylamide gel route was used to prepare SrFe12O19 magnetic nanoparticles; ethylenediaminetetraacetic acid (EDTA) was used as a carboxyl chelating agent. The phase purity, morphology and magnetic properties of as-prepared samples were analyzed via X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometery (VSM). XRD analysis indicates that high-purity SrFe12O19 magnetic nanoparticles can be synthesized at 700°C in air. The characteristic peaks of as-prepared sample at 210, 283, 321, 340, 381, 411, 432, 475, 532, 618, 686, and 726 cm-1 were observed in Raman spectra. SEM and TEM show that the synthesized SrFe12O19 magnetic nanoparticles are uniform with the mean particle size of 60 nm. VSM measurement shows that the maximum magnetic energy product (BH)max of sample prepared using EDTA as a chelating agent is higher than that of sample prepared using citric acid as a chelating agent.

Chemical speciation and mobilization of copper and zinc in naturally contaminated mine soils with citric and tartaric acids.

PubMed

Pérez-Esteban, Javier; Escolástico, Consuelo; Moliner, Ana; Masaguer, Alberto

2013-01-01

A one-step extraction procedure and a leaching column experiment were performed to assess the effects of citric and tartaric acids on Cu and Zn mobilization in naturally contaminated mine soils to facilitate assisted phytoextraction. A speciation modeling of the soil solution and the metal fractionation of soils were performed to elucidate the chemical processes that affected metal desorption by organic acids. Different extracting solutions were prepared, all of which contained 0.01 M KNO(3) and different concentrations of organic acids: control without organic acids, 0.5 mM citric, 0.5 mM tartaric, 10 mM citric, 10 mM tartaric, and 5 mM citric +5 mM tartaric. The results of the extraction procedure showed that higher concentrations of organic acids increased metal desorption, and citric acid was more effective at facilitating metal desorption than tartaric acid. Metal desorption was mainly influenced by the decreasing pH and the dissolution of Fe and Mn oxides, not by the formation of soluble metal-organic complexes as was predicted by the speciation modeling. The results of the column study reported that low concentrations of organic acids did not significantly increase metal mobilization and that higher doses were also not able to mobilize Zn. However, 5-10 mM citric acid significantly promoted Cu mobilization (from 1 mg kg(-1) in the control to 42 mg kg(-1) with 10 mM citric acid) and reduced the exchangeable (from 21 to 3 mg kg(-1)) and the Fe and Mn oxides (from 443 to 277 mg kg(-1)) fractions. Citric acid could efficiently facilitate assisted phytoextraction techniques. Copyright © 2012 Elsevier Ltd. All rights reserved.

A mutation of Aspergillus niger for hyper-production of citric acid from corn meal hydrolysate in a bioreactor.

PubMed

Hu, Wei; Liu, Jing; Chen, Ji-hong; Wang, Shu-yang; Lu, Dong; Wu, Qing-hua; Li, Wen-jian

2014-11-01

The properties of the screened mutants for hyper-production of citric acid induced by carbon ((12)C(6+)) ion beams and X-ray irradiation were investigated in our current study. Among these mutants, mutant H4002 screened from (12)C(6+) ion irradiation had a higher yield of citric acid production than the parental strain in a 250-ml shaking flash. These expanded submerged experiments in a bioreactor were also carried out for mutant H4002. The results showed that (177.7-196.0) g/L citric acid was accumulated by H4002 through exploiting corn meal hydrolysate (containing initial 200.0-235.7 g/L sugar) with the productivity of (2.96-3.27) g/(L∙h). This was especially true when the initial sugar concentration was 210 g/L, and the best economical citric acid production reached (187.5±0.7) g/L with a productivity of 3.13 g/(L∙h). It was observed that mutant H4002 can utilize low-cost corn meal as a feedstock to efficiently produce citric acid. These results imply that the H4002 strain has the industrial production potentiality for citric acid and offers strong competition for the citric acid industry.

A mutation of Aspergillus niger for hyper-production of citric acid from corn meal hydrolysate in a bioreactor*

PubMed Central

Hu, Wei; Liu, Jing; Chen, Ji-hong; Wang, Shu-yang; Lu, Dong; Wu, Qing-hua; Li, Wen-jian

2014-01-01

The properties of the screened mutants for hyper-production of citric acid induced by carbon (12C6+) ion beams and X-ray irradiation were investigated in our current study. Among these mutants, mutant H4002 screened from 12C6+ ion irradiation had a higher yield of citric acid production than the parental strain in a 250-ml shaking flash. These expanded submerged experiments in a bioreactor were also carried out for mutant H4002. The results showed that (177.7–196.0) g/L citric acid was accumulated by H4002 through exploiting corn meal hydrolysate (containing initial 200.0–235.7 g/L sugar) with the productivity of (2.96–3.27) g/(L∙h). This was especially true when the initial sugar concentration was 210 g/L, and the best economical citric acid production reached (187.5±0.7) g/L with a productivity of 3.13 g/(L∙h). It was observed that mutant H4002 can utilize low-cost corn meal as a feedstock to efficiently produce citric acid. These results imply that the H4002 strain has the industrial production potentiality for citric acid and offers strong competition for the citric acid industry. PMID:25367793

Growth/no growth interfaces of table olive related yeasts for natamycin, citric acid and sodium chloride.

PubMed

Arroyo-López, F N; Bautista-Gallego, J; Romero-Gil, V; Rodríguez-Gómez, F; Garrido-Fernández, A

2012-04-16

The present work uses a logistic/probabilistic model to obtain the growth/no growth interfaces of Saccharomyces cerevisiae, Wickerhamomyces anomalus and Candida boidinii (three yeast species commonly isolated from table olives) as a function of the diverse combinations of natamycin (0-30 mg/L), citric acid (0.00-0.45%) and sodium chloride (3-6%). Mathematical models obtained individually for each yeast species showed that progressive concentrations of citric acid decreased the effect of natamycin, which was only observed below 0.15% citric acid. Sodium chloride concentrations around 5% slightly increased S. cerevisiae and C. boidinii resistance to natamycin, although concentrations above 6% of NaCl always favoured inhibition by this antimycotic. An overall growth/no growth interface, built considering data from the three yeast species, revealed that inhibition in the absence of citric acid and at 4.5% NaCl can be reached using natamycin concentrations between 12 and 30 mg/L for growth probabilities between 0.10 and 0.01, respectively. Results obtained in this survey show that is not advisable to use jointly natamycin and citric acid in table olive packaging because of the observed antagonistic effects between both preservatives, but table olives processed without citric acid could allow the application of the antifungal. Copyright © 2012 Elsevier B.V. All rights reserved.

The Role of Citric Acid in the Stabilization of Nanoparticles and Colloidal Particles in the Environment: Measurement of Surface Forces between Hafnium Oxide Surfaces in the Presence of Citric Acid.

PubMed

Shinohara, Shuhei; Eom, Namsoon; Teh, E-Jen; Tamada, Kaoru; Parsons, Drew; Craig, Vincent S J

2018-02-27

The interactions between colloidal particles and nanoparticles determine solution stability and the structures formed when the particles are unstable to flocculation. Therefore, knowledge of the interparticle interactions is important for understanding the transport, dissolution, and fate of particles in the environment. The interactions between particles are governed by the surface properties of the particles, which are altered when species adsorb to the surface. The important interactions in the environment are almost never those between the bare particles but rather those between particles that have been modified by the adsorption of natural organic materials. Citric acid is important in this regard not only because it is present in soil but also as a model of humic and fulvic acids. Here we have studied the surface forces between the model metal oxide surface hafnia in the presence of citric acid in order to understand the stability of colloidal particles and nanoparticles. We find that citric acid stabilizes the particles over a wide range of pH at low to moderate ionic strength. At high ionic strength, colloidal particles will flocculate due to a secondary minimum, resulting in aggregates that are dense and easily redispersed. In contrast, nanoparticles stabilized by citric acid remain stable at high ionic strengths and therefore exist in solution as individual particles; this will contribute to their dispersion in the environment and the uptake of nanoparticles by mammalian cells.

76 FR 4288 - Citric Acid and Certain Citrate Salts From the People's Republic of China: Notice of Extension of...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-01-25

... DEPARTMENT OF COMMERCE International Trade Administration [A-570-937] Citric Acid and Certain...'') published the initiation of the administrative review of the antidumping duty order on citric acid and certain citrate salts (``citric acid'') from the People's Republic of China (``PRC''). See Initiation of...

Fabrication of calcium phosphate–calcium sulfate injectable bone substitute using hydroxy-propyl-methyl-cellulose and citric acid

PubMed Central

Thai, Van Viet

2010-01-01

In this study, an injectable bone substitute (IBS) consisting of citric acid, chitosan, and hydroxyl propyl methyl cellulose (HPMC) as the liquid phase and tetra calcium phosphate (TTCP), dicalcium phosphate dihydrate (DCPD) and calcium sulfate dehydrate (CSD, CaSO4·2H2O) powders as the solid phase, were fabricated. Two groups were classified based on the percent of citric acid in the liquid phase (20, 40 wt%). In each groups, the HPMC percentage was 0, 2, and 4 wt%. An increase in compressive strength due to changes in morphology was confirmed by scanning electron microscopy images. A good conversion rate of HAp at 20% citric acid was observed in the XRD profiles. In addition, HPMC was not obviously affected by apatite formation. However, both HPMC and citric acid increased the compressive strength of IBS. The maximum compressive strength for IBS was with 40% citric acid and 4% HPMC after 14 days of incubation in 100% humidity at 37°C. PMID:20333539

Removal of heavy metals from polluted soil using the citric acid fermentation broth: a promising washing agent.

PubMed

Zhang, Hongjiao; Gao, Yuntao; Xiong, Huabin

2017-04-01

The citric acid fermentation broth was prepared and it was employed to washing remediation of heavy metal-polluted soil. A well-defined washing effect was obtained, the removal percentages using citric acid fermentation broth are that 48.2% for Pb, 30.6% for Cu, 43.7% for Cr, and 58.4% for Cd and higher than that using citric acid solution. The kinetics of heavy metals desorption can be described by the double constant equation and Elovich equation and is a heterogeneous diffusion process. The speciation analysis shows that the citric acid fermentation broth can effectively reduce bioavailability and environmental risk of heavy metals. Spectroscopy characteristics analysis suggests that the washing method has only a small effect on the mineral composition and does not destroy the framework of soil system. Therefore, the citric acid fermentation broth is a promising washing agent and possesses a potential practical application value in the field of remediation of soils with a good washing performance.

Influence of Citric Acid on the Pink Color and Characteristics of Sous Vide Processed Chicken Breasts During Chill Storage

PubMed Central

Lim, Ki-Won

2015-01-01

Chicken breast dipped with citric acid (CA) was treated by sous vide processing and stored in a refrigerated state for 0, 3, 6, 9, and 14 d. A non-dipped control group (CON) and three groups dipped in different concentrations of citric acid concentration were analyzed (0.5%, 0.5CIT; 2.0%, 2CIT and 5.0%, 5CIT; w/v). Cooking yield and moisture content increased due to the citric acid. While the redness of the juice and meat in all groups showed significant increase during storage, the redness of the citric acid groups was reduced compared to the control group (p<0.05). The percentage of myoglobin denaturation (PMD) of the CA groups was also increased according to the level of CA during storage. Total aerobic counts, Enterobacteriaceae counts, volatile basic nitrogen and thiobarbituric acid reactive substances (TBARS) were generally lower in the citric acid-treated samples than in untreated ones, indicating extended shelf life of the cooked chicken breast dipped in citric acid solution. The shear force of the 2CIT and 5CIT groups was significantly lower (p<0.05). The findings indicated positive effects in the physicochemical properties and storage ability of sous vide chicken breast at 2% and 5% citric acid concentrations. PMID:26761885

Simultaneous Removal of Lindane, Lead and Cadmium from Soils by Rhamnolipids Combined with Citric Acid.

PubMed

Wan, Jinzhong; Meng, Die; Long, Tao; Ying, Rongrong; Ye, Mao; Zhang, Shengtian; Li, Qun; Zhou, Yan; Lin, Yusuo

2015-01-01

This study investigated the performance of rhamnolipids-citric acid mixed agents in simultaneous desorption of lindane and heavy metals from soils. The capacity of the mixed agents to solubilize lindane, lead and cadmium in aqueous solution was also explored. The results showed that the presence of citric acid greatly enhanced the solubilization of lindane and cadmium by rhamnolipids. A combined effect of the mixed agents on lindane and heavy metals removal from soils was observed. The maximum desorption ratios for lindane, cadmium and lead were 85.4%, 76.4% and 28.1%, respectively, for the mixed agents containing 1% rhamnolipidsand 0.1 mol/L citric acid. The results also suggest that the removal efficiencies of lead and cadmium were strongly related to their speciations in soils, and metals in the exchangeable and carbonate forms were easier to be removed. Our study suggests that the combining use of rhamnolipids and citric acid is a promising alternative to simultaneously remove organochlorine pesticides and heavy metals from soils.

Simultaneous Removal of Lindane, Lead and Cadmium from Soils by Rhamnolipids Combined with Citric Acid

PubMed Central

Long, Tao; Ying, Rongrong; Ye, Mao; Zhang, Shengtian; Li, Qun; Zhou, Yan; Lin, Yusuo

2015-01-01

This study investigated the performance of rhamnolipids-citric acid mixed agents in simultaneous desorption of lindane and heavy metals from soils. The capacity of the mixed agents to solubilize lindane, lead and cadmium in aqueous solution was also explored. The results showed that the presence of citric acid greatly enhanced the solubilization of lindane and cadmium by rhamnolipids. A combined effect of the mixed agents on lindane and heavy metals removal from soils was observed. The maximum desorption ratios for lindane, cadmium and lead were 85.4%, 76.4% and 28.1%, respectively, for the mixed agents containing 1% rhamnolipidsand 0.1 mol/L citric acid. The results also suggest that the removal efficiencies of lead and cadmium were strongly related to their speciations in soils, and metals in the exchangeable and carbonate forms were easier to be removed. Our study suggests that the combining use of rhamnolipids and citric acid is a promising alternative to simultaneously remove organochlorine pesticides and heavy metals from soils. PMID:26087302

The global regulator LaeA controls production of citric acid and endoglucanases in Aspergillus carbonarius.

PubMed

Linde, Tore; Zoglowek, Marta; Lübeck, Mette; Frisvad, Jens Christian; Lübeck, Peter Stephensen

2016-08-01

The global regulatory protein LaeA is known for regulating the production of many kinds of secondary metabolites in Aspergillus species, as well as sexual and asexual reproduction, and morphology. In Aspergillus carbonarius, it has been shown that LaeA regulates production of ochratoxin. We have investigated the regulatory effect of LaeA on production of citric acid and cellulolytic enzymes in A. carbonarius. Two types of A. carbonarius strains, having laeA knocked out or overexpressed, were constructed and tested in fermentation. The knockout of laeA significantly decreased the production of citric acid and endoglucanases, but did not reduce the production of beta-glucosidases or xylanases. The citric acid accumulation was reduced with 74-96 % compared to the wild type. The endoglucanase activity was reduced with 51-78 %. Overexpression of LaeA seemed not to have an effect on citric acid production or on cellulose or xylanase activity.

Enhanced solid-state citric acid bio-production using apple pomace waste through surface response methodology.

PubMed

Dhillon, G S; Brar, S K; Verma, M; Tyagi, R D

2011-04-01

  To evaluate the potential of apple pomace (AP) supplemented with rice husk for hyper citric acid production through solid-state fermentation by Aspergillus niger NRRL-567. Optimization of two key parameters, such as moisture content and inducer (ethanol and methanol) concentration was carried out by response surface methodology.   In this study, the effect of two crucial process parameters for solid-state citric acid fermentation by A. niger using AP waste supplemented with rice husk were thoroughly investigated in Erlenmeyer flasks through response surface methodology. Moisture and methanol had significant positive effect on citric acid production by A. niger grown on AP (P < 0·05). Higher values of citric acid on AP by A. niger (342·41gkg(-1) and 248·42gkg(-1) dry substrate) were obtained with 75% (v/w) moisture along with two inducers [3% (v/w) methanol and 3% (v/w) ethanol] with fermentation efficiency of 93·90% and 66·42%, respectively depending upon the total carbon utilized after 144h of incubation period. With the same optimized parameters, conventional tray fermentation was conducted. The citric acid concentration of 187·96gkg(-1) dry substrate with 3% (v/w) ethanol and 303·34gkg(-1) dry substrate with 3% (v/w) methanol were achieved representing fermentation efficiency of 50·80% and 82·89% in tray fermentation depending upon carbon utilization after 120h of incubation period.   Apple pomace proved to be the promising substrate for the hyper production of citric acid through solid-state tray fermentation, which is an economical technique and does not require any sophisticated instrumentation.   The study established that the utilization of agro-industrial wastes have positive repercussions on the economy and will help to meet the increasing demands of citric acid and moreover will help to alleviate the environmental problems resulting from the disposal of agro-industrial wastes. © 2011 The Authors. Journal of Applied Microbiology �

Gamma irradiation of isocitric and citric acid in aqueous solution: Relevance in prebiotic chemistry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Negrón-Mendoza, A., E-mail: negron@nucleares.unam.mx; Ramos-Bernal, S.

The radiation chemistry of hydroxy acids like citric and isocitric acids is rather scarce, even though they are crucial compounds in biological systems and for food irradiation. The aim of this work is to study the radiolytic behavior of these acids focused on the interconversion induced by radiation of citric and isocitric acid into other members of the Krebs cycle. The results showed that among the products formed were succinic, malonic, malic and other acids related to metabolic pathways, and these results are correlated with its possible role in chemical evolution processes.

A comparative study on glycerol metabolism to erythritol and citric acid in Yarrowia lipolytica yeast cells.

PubMed

Tomaszewska, Ludwika; Rakicka, Magdalena; Rymowicz, Waldemar; Rywińska, Anita

2014-09-01

Citric acid and erythritol biosynthesis from pure and crude glycerol by three acetate-negative mutants of Yarrowia lipolytica yeast was investigated in batch cultures in a wide pH range (3.0-6.5). Citric acid biosynthesis was the most effective at pH 5.0-5.5 in the case of Wratislavia 1.31 and Wratislavia AWG7. With a decreasing pH value, the direction of biosynthesis changed into erythritol synthesis accompanied by low production of citric acid. Pathways of glycerol conversion into erythritol and citric acid were investigated in Wratislavia K1 cells. Enzymatic activity was compared in cultures run at pH 3.0 and 4.5, that is, under conditions promoting the production of erythritol and citric acid, respectively. The effect of pH value (3.0 and 4.5) and NaCl presence on the extracellular production and intracellular accumulation of citric acid and erythritol was compared as well. Low pH and NaCl resulted in diminished activity of glycerol kinase, whereas such conditions stimulated the activity of glycerol-3-phosphate dehydrogenase. The presence of NaCl strongly influenced enzymes activity - the effective erythritol production was correlated with a high activity of transketolase and erythrose reductase. Therefore, presented results confirmed that transketolase and erythrose reductase are involved in the overproduction of erythritol in the cells of Y. lipolytica yeast. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Phosphate recovery through struvite-family crystals precipitated in the presence of citric acid: mineralogical phase and morphology evaluation.

PubMed

Perwitasari, D S; Edahwati, L; Sutiyono, S; Muryanto, S; Jamari, J; Bayuseno, A P

2017-11-01

Precipitation strategy of struvite-family crystals is presented in this paper to recover phosphate and potassium from a synthetic wastewater in the presence of citric acid at elevated temperature. The crystal-forming solutions were prepared from crystals of MgCl 2 and NH 4 H 2 PO 4 with a molar ratio of 1:1:1 for Mg +2 , [Formula: see text], and [Formula: see text], and the citric acid (C 6 H 8 O 7 ) was prepared (1.00 and 20.00 ppm) from citric acid crystals. The Rietveld analysis of X-ray powder diffraction pattern confirmed a mixed product of struvite, struvite-(K), and newberyite crystallized at 30°C in the absence of citric acid. In the presence of citric acid at 30° and 40°C, an abundance of struvite and struvite-(K) were observed. A minute impurity of sylvite and potassium peroxide was unexpectedly found in certain precipitates. The crystal solids have irregular flake-shaped morphology, as shown by scanning electron microscopy micrograph. All parameters (citric acid, temperature, pH, Mg/P, and N/P) were deliberately arranged to control struvite-family crystals precipitation.

Differential effects of citric acid on cadmium uptake and accumulation between tall fescue and Kentucky bluegrass.

PubMed

Wang, ShuTing; Dong, Qin; Wang, ZhaoLong

2017-11-01

Organic acids play an important role in cadmium availability, uptake, translocation, and detoxification. A sand culture experiment was designed to investigate the effects of citric acid on Cd uptake, translocation, and accumulation in tall fescue and Kentucky bluegrass. The results showed that two grass species presented different Cd chemical forms, organic acid components and amount in roots. The dormant Cd accumulated in roots of tall fescue was the pectate- and protein- integrated form, which contributed by 84.85%. However, in Kentucky bluegrass, the pectate- and protein- integrated Cd was only contributed by 35.78%, and the higher proportion of Cd form was the water soluble Cd-organic acid complexes. In tall fescue, citric acid dramatically enhanced 2.8 fold of Cd uptake, 3 fold of root Cd accumulation, and 2.3 fold of shoot Cd accumulation. In Kentucky bluegrass, citric acid promoted Cd accumulation in roots, but significantly decreased Cd accumulation in shoots. These results suggested that the enhancements of citric acid on Cd uptake, translocation, and accumulation in tall fescue was associated with its promotion of organic acids and the water soluble Cd-organic acid complexes in roots. Copyright © 2017 Elsevier Inc. All rights reserved.

Citric Acid and Quinine Share Perceived Chemosensory Features Making Oral Discrimination Difficult in C57BL/6J Mice

PubMed Central

Treesukosol, Yada; Mathes, Clare M.

2011-01-01

Evidence in the literature shows that in rodents, some taste-responsive neurons respond to both quinine and acid stimuli. Also, under certain circumstances, rodents display some degree of difficulty in discriminating quinine and acid stimuli. Here, C57BL/6J mice were trained and tested in a 2-response operant discrimination task. Mice had severe difficulty discriminating citric acid from quinine and 6-n-propylthiouracil (PROP) with performance slightly, but significantly, above chance. In contrast, mice were able to competently discriminate sucrose from citric acid, NaCl, quinine, and PROP. In another experiment, mice that were conditioned to avoid quinine by pairings with LiCl injections subsequently suppressed licking responses to quinine and citric acid but not to NaCl or sucrose in a brief-access test, relative to NaCl-injected control animals. However, mice that were conditioned to avoid citric acid did not display cross-generalization to quinine. These mice significantly suppressed licking only to citric acid, and to a much lesser extent NaCl, compared with controls. Collectively, the findings from these experiments suggest that in mice, citric acid and quinine share chemosensory features making discrimination difficult but are not perceptually identical. PMID:21421543

Quantitative Determination of Citric and Ascorbic Acid in Powdered Drink Mixes

ERIC Educational Resources Information Center

Sigmann, Samuella B.; Wheeler, Dale E.

2004-01-01

A procedure by which the reactions are used to quantitatively determine the amount of total acid, the amount of total ascorbic acid and the amount of citric acid in a given sample of powdered drink mix, are described. A safe, reliable and low-cost quantitative method to analyze consumer product for acid content is provided.

Simulation of the influence of EDTA on the sorption of heavy metals by humic acids

NASA Astrophysics Data System (ADS)

Kropacheva, T. N.; Didik, M. V.; Kornev, V. I.

2015-04-01

The results of mathematical simulation of sorption equilibria with the participation of divalent cations of heavy metals (HMs), chelant (EDTA), and insoluble forms of humic acids (HAs) are discussed. It is shown that the formation of chelates of metals with EDTA in solutions results in the decreasing sorption of the metals by humic acids. We also analyzed the effect of the acidity of the medium and the HM: EDTA: HA ratio (in a wide range) on the desorption of metals. The desorbing effect of EDTA on the metals is the highest at pH 3-5 and increases with an increase in the concentration of EDTA and a decrease in the concentration of HAs. With respect to the remobilization of metals under the impact of EDTA, the metal cations can be arranged into the following sequence: Cu(II) > Ni(II) > Pb(II) ≫ Cd(II) > Co(II) > Zn(II). The obtained data have been used to analyze the remobilization / extraction of HMs from soils with a high content of humic substances.

Effect of citric acid concentration and hydrolysis time on physicochemical properties of sweet potato starches.

PubMed

Surendra Babu, Ayenampudi; Parimalavalli, Ramanathan; Rudra, Shalini Gaur

2015-09-01

Physicochemical properties of citric acid treated sweet potato starches were investigated in the present study. Sweet potato starch was hydrolyzed using citric acid with different concentrations (1 and 5%) and time periods (1 and 11 h) at 45 °C and was denoted as citric acid treated starch (CTS1 to CTS4) based on their experimental conditions. The recovery yield of acid treated starches was above 85%. The CTS4 sample displayed the highest amylose (around 31%) and water holding capacity its melting temperature was 47.66 °C. The digestibility rate was slightly increased for 78.58% for the CTS3 and CTS4. The gel strength of acid modified starches ranged from 0.27 kg to 1.11 kg. RVA results of acid thinned starches confirmed a low viscosity profile. CTS3 starch illustrated lower enthalpy compared to all other modified starches. All starch samples exhibited a shear-thinning behavior. SEM analysis revealed that the extent of visible degradation was increased at higher hydrolysis time and acid concentration. The CTS3 satisfied the criteria required for starch to act as a fat mimetic. Overall results conveyed that the citric acid treatment of sweet potato starch with 5% acid concentration and 11h period was an ideal condition for the preparation of a fat replacer. Copyright © 2015 Elsevier B.V. All rights reserved.

Citric acid compounds of tangerines peel extract (Citrus reticulata) as potential materials teeth whitening

NASA Astrophysics Data System (ADS)

Pratiwi, F.; Tinata, J. K.; Prakasa, A. W.; Istiqomah; Hartini, E.; Isworo, S.

2017-04-01

Peel of citrus fruit (Citrus reticulata) has a variety of possible chemical compounds that may serve as a potential whitening teeth. This research is conducted on a laboratory scale; therefore, it needs to be developed on an application scale. A quasi-experimental was employed in this study. Citric acid extraction was carried out on the type of Sweet Orange (Citrus Aurantium L), Tangerine (Citrus Reticulata Blanco or Citrus Nobilis), Pomelo (Citrus Maxima Merr, Citrus grandis Osbeck), and Lemon (Citrus Limon Linn). Citric acid’s ability test as teeth whitener was performed on premolar teeth with concentrations of 2.5%, 5%, and 10%. The experiments were replicated in 3 times, and teeth whiteness level was measured using Shade Guide VITA Classical. The result of this research showed that citric acid in every kind of orange peel with various concentration has different abilities on whitening teeth. The highest colour level obtained from Tangerine peel’s citric acid concentration of 5%. Orange peel extract has the best teeth whitening abilities tested by the method of Gass Chromatography to know the active ingredients.

Citric acid application for denitrification process support in biofilm reactor.

PubMed

Mielcarek, Artur; Rodziewicz, Joanna; Janczukowicz, Wojciech; Dabrowska, Dorota; Ciesielski, Slawomir; Thornton, Arthur; Struk-Sokołowska, Joanna

2017-03-01

The study demonstrated that citric acid, as an organic carbon source, can improve denitrification in Anaerobic Sequencing Batch Biofilm Reactor (AnSBBR). The consumption rate of the organic substrate and the denitrification rate were lower during the period of the reactor's acclimatization (cycles 1-60; 71.5 mgCOD L -1  h -1 and 17.81 mgN L -1  h -1 , respectively) than under the steady state conditions (cycles 61-180; 143.8 mgCOD L -1  h -1 and 24.38 mgN L -1  h -1 ). The biomass yield coefficient reached 0.04 ± 0.02 mgTSS· mgCOD re -1 (0.22 ± 0.09 mgTSS mgN re -1 ). Observations revealed the diversified microbiological ecology of the denitrifying bacteria. Citric acid was used mainly by bacteria representing the Trichoccocus genus, which represented above 40% of the sample during the first phase of the process (cycles 1-60). In the second phase (cycles 61-180) the microorganisms the genera that consumed the acetate and formate, as the result of citric acid decomposition were Propionibacterium (5.74%), Agrobacterium (5.23%), Flavobacterium (1.32%), Sphaerotilus (1.35%), Erysipelothrix (1.08%). Copyright © 2016 Elsevier Ltd. All rights reserved.

Synergistic antimicrobial activity of caprylic acid in combination with citric acid against both Escherichia coli O157:H7 and indigenous microflora in carrot juice.

PubMed

Kim, S A; Rhee, M S

2015-08-01

The identification of novel, effective, and non-thermal decontamination methods is imperative for the preservation of unpasteurized and fresh vegetable juices. The aim of this study was to examine the bactericidal effects of caprylic acid + citric acid against the virulent pathogen Escherichia coli O157:H7 and the endogenous microflora in unpasteurized fresh carrot juice. Carrot juice was treated with either caprylic acid, citric acid, or a combination of caprylic acid + citric acid at mild heating temperature (45 °C or 50 °C). The color of the treated carrot juice as well as microbial survival was examined over time. Combined treatment was more effective than individual treatment in terms of both color and microbial survival. Caprylic acid + citric acid treatment (each at 5.0 mM) at 50 °C for 5 min resulted in 7.46 and 3.07 log CFU/ml reductions in the E. coli O157:H7 and endogenous microflora populations, respectively. By contrast, there was no apparent reduction in either population following individual treatment. A validation assay using a low-density E. coli O157:H7 inoculum (3.31 log CFU/ml) showed that combined treatment with caprylic acid (5.0 mM) + citric acid (2.5 mM) at 50 °C for >5 min or with caprylic acid + citric acid (both at 5.0 mM) at either 45 °C or 50 °C for >5 min completely destroyed the bacteria. Combined treatment also increased the redness of the juice, which is a perceived indication of quality. Taken together, these results indicate that combined treatment with low concentrations of caprylic acid and citric acid, which are of biotic origin, can eliminate microorganisms from unpasteurized carrot juice. Copyright © 2015 Elsevier Ltd. All rights reserved.

Continuous citric acid production in repeated-fed batch fermentation by Aspergillus niger immobilized on a new porous foam.

PubMed

Yu, Bin; Zhang, Xin; Sun, Wenjun; Xi, Xun; Zhao, Nan; Huang, Zichun; Ying, Zhuojun; Liu, Li; Liu, Dong; Niu, Huanqing; Wu, Jinglan; Zhuang, Wei; Zhu, Chenjie; Chen, Yong; Ying, Hanjie

2018-06-20

The efficiency of current methods for industrial production of citric acid is limited. To achieve continuous citric acid production with enhanced yield and reduced cost, immobilized fermentation was employed in an Aspergillus niger 831 repeated fed-batch fermentation system. We developed a new type of material (PAF201), which was used as a carrier for the novel adsorption immobilization system. Hydrophobicity, pore size and concentration of carriers were researched in A. niger immobilization. The efficiency of the A. niger immobilization process was analyzed by scanning electron microscopy. Then eight-cycle repeated fed-batch cultures for citric acid production were carried out over 600 h, which showed stable production with maximum citric acid concentrations and productivity levels of 162.7 g/L and 2.26 g L -1  h -1 , respectively. Compared with some other literatures about citric acid yield, PAF201 immobilization system is 11.3% higher than previous results. These results indicated that use of the new adsorption immobilization system could greatly improve citric acid productivity in repeated fed-batch fermentation. Moreover, these results could provide a guideline for A.niger or other filamentous fungi immobilization in industry. Copyright © 2018 Elsevier B.V. All rights reserved.

The effect of theobromine 200 mg/l topical gel exposure duration against surface enamel hardness resistance from 1% citric acid

NASA Astrophysics Data System (ADS)

Herisa, H. M.; Noerdin, A.; Eriwati, Y. K.

2017-08-01

Theobromine can be used to prevent the demineralization of enamel and can stimulate the growth of new enamels. This study analyzes the effect of theobromine’s gel duration exposure on enamel hardness resistance from 1% citric acid. Twenty-eight specimens were divided into three experimental groups; were exposed to theobromine gel 200 mg/l for 16, 48, and 96 minutes; and were then immersed in 1% citric acid. The control group was only immersed in 1% citric acid. Results: A Wilcoxon test showed a significant increase and decrease in enamel microhardness after exposure to theobromine gel and citric acid (p < 0.05). A Mann-Whitney test showed a significant increase and decrease in enamel microhardness between different durations of exposure to theobromine gel and immersion in citric acid (p < 0.05). The application of theobromine gel 200mg/L increased enamel microhardness but did not contribute to the enamel’s hardness resistance after immersion in 1% citric acid. The duration of theobromine gel application affected enamel microhardness and acid resistance.

The Role of Citric Acid in Perfecting Platinum Monolayer on Palladium Nanoparticles during the Surface Limited Redox Replacement Reaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Shangqian; Yue, Jeffrey; Qin, Xueping

Cu-mediated-Pt-displacement method that involves the displacement of an underpotentially deposited (UPD) Cu monolayer by Pt has been extensively studied to prepare core-shell catalysts. It has been found that Pt clusters instead of a uniform Pt monolayer were formed in the gram batch synthesis. With a suitable surfactant, such as citric acid, the Pt shell could be much more uniform. In this study, the role of citric acid in controlling the Cu-Pt displacement reaction kinetics was studied by electrochemical techniques and theoretical approaches. It was found that citric acid strongly adsorbed on Pd, Pt, Cu/Pd, and Pt/Pd surfaces, especially in themore » double layer region in acid solutions. The strong adsorption of citric acid slowed down the Cu-Pt displacement reaction. The main characteristics of such strong interaction most likely arises from the OH groups in the citric acid molecule according to the molecular dynamics simulation results.« less

The Role of Citric Acid in Perfecting Platinum Monolayer on Palladium Nanoparticles during the Surface Limited Redox Replacement Reaction

DOE PAGES

Zhu, Shangqian; Yue, Jeffrey; Qin, Xueping; ...

2016-07-28

Cu-mediated-Pt-displacement method that involves the displacement of an underpotentially deposited (UPD) Cu monolayer by Pt has been extensively studied to prepare core-shell catalysts. It has been found that Pt clusters instead of a uniform Pt monolayer were formed in the gram batch synthesis. With a suitable surfactant, such as citric acid, the Pt shell could be much more uniform. In this study, the role of citric acid in controlling the Cu-Pt displacement reaction kinetics was studied by electrochemical techniques and theoretical approaches. It was found that citric acid strongly adsorbed on Pd, Pt, Cu/Pd, and Pt/Pd surfaces, especially in themore » double layer region in acid solutions. The strong adsorption of citric acid slowed down the Cu-Pt displacement reaction. The main characteristics of such strong interaction most likely arises from the OH groups in the citric acid molecule according to the molecular dynamics simulation results.« less

Leaching of metals from large pieces of printed circuit boards using citric acid and hydrogen peroxide.

PubMed

Jadhav, Umesh; Su, C; Hocheng, Hong

2016-12-01

In the present study, the leaching of metals from large pieces of computer printed circuit boards (CPCBs) was studied. A combination of citric acid (0.5 M) and 1.76 M hydrogen peroxide (H 2 O 2 ) was used to leach the metals from CPCB piece. The influence of system variables such as H 2 O 2 concentration, concentration of citric acid, shaking speed, and temperature on the metal leaching process was investigated. The complete metal leaching was achieved in 4 h from a 4 × 4 cm CPCB piece. The presence of citric acid and H 2 O 2 together in the leaching solution is essential for complete metal leaching. The optimum addition amount of H 2 O 2 was 5.83 %. The citric acid concentration and shaking speed had an insignificant effect on the leaching of metals. The increase in the temperature above 30 °C showed a drastic effect on metal leaching process.

Influence of concentration, time and method of application of citric acid and sodium citrate in root conditioning

PubMed Central

CAVASSIM, Rodrigo; LEITE, Fábio Renato Manzolli; ZANDIM, Daniela Leal; DANTAS, Andrea Abi Rached; RACHED, Ricardo Samih Georges Abi; SAMPAIO, José Eduardo Cezar

2012-01-01

Objective The aim of this study was to establish the parameters of concentration, time and mode of application of citric acid and sodium citrate in relation to root conditioning. Material and Methods A total of 495 samples were obtained and equally distributed among 11 groups (5 for testing different concentrations of citric acid, 5 for testing different concentrations of sodium citrate and 1 control group). After laboratorial processing, the samples were analyzed under scanning electron microscopy. A previously calibrated and blind examiner evaluated micrographs of the samples. Non-parametric statistical analysis was performed to analyze the data obtained. Results Brushing 25% citric acid for 3 min, promoted greater exposure of collagen fibers in comparison with the brushing of 1% citric acid for 1 minute and its topical application at 1% for 3 min. Sodium citrate exposed collagen fibers in a few number of samples. Conclusion Despite the lack of statistical significance, better results for collagen exposure were obtained with brushing application of 25% citric acid for 3 min than with other application parameter. Sodium citrate produced a few number of samples with collagen exposure, so it is not indicated for root conditioning. PMID:22858707

Pd/C Synthesized with Citric Acid: An Efficient Catalyst for Hydrogen Generation from Formic Acid/Sodium Formate

PubMed Central

Wang, Zhi-Li; Yan, Jun-Min; Wang, Hong-Li; Ping, Yun; Jiang, Qing

2012-01-01

A highly efficient hydrogen generation from formic acid/sodium formate aqueous solution catalyzed by in situ synthesized Pd/C with citric acid has been successfully achieved at room temperature. Interestingly, the presence of citric acid during the formation and growth of the Pd nanoparticles on carbon can drastically enhance the catalytic property of the resulted Pd/C, on which the conversion and turnover frequency for decomposition of formic acid/sodium formate system can reach the highest values ever reported of 85% within 160 min and 64 mol H2 mol−1 catalyst h−1, respectively, at room temperature. The present simple, low cost, but highly efficient CO-free hydrogen generation system at room temperature is believed to greatly promote the practical application of formic acid system on fuel cells. PMID:22953041

Resin–dentin bonds to EDTA-treated vs. acid-etched dentin using ethanol wet-bonding

PubMed Central

Sauro, Salvatore; Toledano, Manuel; Aguilera, Fatima Sánchez; Mannocci, Francesco; Pashley, David H.; Tay, Franklin R.; Watson, Timothy F.; Osorio, Raquel

2013-01-01

Objective To compare resin–dentin bond strengths and the micropermeability of hydrophobic vs. hydrophilic resins bonded to acid-etched or EDTA-treated dentin, using the ethanol wet-bonding technique. Methods Flat dentin surfaces from extracted human third molars were conditioned before bonding with: 37% H3PO4 (15 s) or 0.1 M EDTA (60 s). Five experimental resin blends of different hydrophilicities and one commercial adhesive (SBMP: Scotchbond Multi-Purpose) were applied to ethanol wet-dentin (1 min) and light-cured (20 s). The solvated resins were used as primers (50% ethanol/50% comonomers) and their respective neat resins were used as the adhesive. The resin-bonded teeth were stored in distilled water (24 h) and sectioned in beams for microtensile bond strength testing. Modes of failure were examined by stereoscopic light microscopy and SEM. Confocal tandem scanning microscopy (TSM) interfacial characterization and micropermeability were also performed after filling the pulp chamber with 1 wt% aqueous rhodamine-B. Results The most hydrophobic resin 1 gave the lowest bond strength values to acid-etched dentin and all beams failed prematurely when the resin was applied to EDTA-treated dentin. Resins 2 and 3 gave intermediate bond strengths to both conditioned substrates. Resin 4, an acidic hydrophilic resin, gave the highest bond strengths to both EDTA-treated and acid-etched dentin. Resin 5 was the only hydrophilic resin showing poor resin infiltration when applied on acid-etched dentin. Significance The ethanol wet-bonding technique may improve the infiltration of most of the adhesives used in this study into dentin, especially when applied to EDTA-treated dentin. The chemical composition of the resin blends was a determining factor influencing the ability of adhesives to bond to EDTA-treated or 37% H3PO4 acid-etched dentin, when using the ethanol wet-bonding technique in a clinically relevant time period. PMID:20074787

Experimental design data for the biosynthesis of citric acid using Central Composite Design method.

PubMed

Kola, Anand Kishore; Mekala, Mallaiah; Goli, Venkat Reddy

2017-06-01

In the present investigation, we report that statistical design and optimization of significant variables for the microbial production of citric acid from sucrose in presence of filamentous fungi A. niger NCIM 705. Various combinations of experiments were designed with Central Composite Design (CCD) of Response Surface Methodology (RSM) for the production of citric acid as a function of six variables. The variables are; initial sucrose concentration, initial pH of medium, fermentation temperature, incubation time, stirrer rotational speed, and oxygen flow rate. From experimental data, a statistical model for this process has been developed. The optimum conditions reported in the present article are initial concentration of sucrose of 163.6 g/L, initial pH of medium 5.26, stirrer rotational speed of 247.78 rpm, incubation time of 8.18 days, fermentation temperature of 30.06 °C and flow rate of oxygen of 1.35 lpm. Under optimum conditions the predicted maximum citric acid is 86.42 g/L. The experimental validation carried out under the optimal values and reported citric acid to be 82.0 g/L. The model is able to represent the experimental data and the agreement between the model and experimental data is good.

By-products from the biodiesel chain as a substrate to citric acid production by solid-state fermentation.

PubMed

Schneider, Manuella; Zimmer, Gabriela F; Cremonese, Ezequiel B; de C de S Schneider, Rosana; Corbellini, Valeriano A

2014-07-01

In this study, we propose the use of tung cake for the production of organic acids, with an emphasis on citric acid by solid-state fermentation. We evaluated the conditions of production and the by-products from the biodiesel chain as raw materials involved in this bioprocess. First, we standardized the conditions of solid-state fermentation in tung cake with and without residual fat and with different concentrations of glycerine using the fungus Aspergillus niger The solid-state fermentation process was monitored for 7 days considering the biomass growth and pH level. Citric acid production was determined by high-performance liquid chromatography. Fungal development was better in the crude tung cake, consisting of 20% glycerine. The highest citric acid yield was 350 g kg(-1) of biomass. Therefore, the solid-state fermentation of the tung cake with glycerine led to citric acid production using the Aspergillus niger fungus. © The Author(s) 2014.

Development of anti-scale poly(aspartic acid-citric acid) dual polymer systems for water treatment.

PubMed

Nayunigari, Mithil Kumar; Gupta, Sanjay Kumar; Kokkarachedu, Varaprasad; Kanny, K; Bux, F

2014-01-01

The formation of calcium sulphate and calcium carbonate scale poses major problems in heat exchangers and water cooling systems, thereby affecting the performance of these types of equipment. In order to inhibit these scale formations, new types of biodegradable water soluble single polymer and dual poly(aspartic acid-citric acid) polymers were developed and tested. The effectiveness of single polymer and four different compositions of poly aspartic acid and citric acid dual polymer systems as scale inhibitors were evaluated. Details of the synthesis, thermal stability, scale inhibition and the morphological characterization of single and dual polymers are presented in this scientific paper. It was found that the calcium sulphate scale inhibition rate was in the range 76.06-91.45%, while the calcium carbonate scale inhibition rate observed was in the range 23.37-30.0% at 65-70 °C. The finding suggests that the water soluble dual polymers are very effective in sulphate scale inhibition in comparison of calcium carbonate scale inhibition.

Evaluation of ethylenediaminetetraacetic acid (EDTA) solution and gel for smear layer removal.

PubMed

Dotto, Sidney Ricardo; Travassos, Rosana Maria Coelho; de Oliveira, Elias Pandonor Motcy; Machado, Manoel Eduardo de Lima; Martins, José Luiz

2007-08-01

The purpose of this in vitro study was to compare the efficacy of 24% ethylenediaminetetraacetic acid (EDTA) gel and 17% EDTA solution in cleaning dentine walls after root canal instrumentation. Thirty human canine teeth were divided into three groups of 10 teeth each. In Group 1, 1% sodium hypochlorite was used as the irrigating solution; in Group 2, 1% sodium hypochlorite was used with 17% EDTA solution; and in Group 3, 1% sodium hypochlorite was used with 24% EDTA gel. The presence of a smear layer was analysed after instrumentation using scanning electron microscopy. The Kruskal-Wallis test revealed a statistical difference (P < 0.05) between Groups 1 and 2, and also between Groups 1 and 3. No difference was observed between Groups 2 and 3 (P > 0.05). The results indicate that 1% sodium hypochlorite alone does not remove the smear layer and that there was no statistical difference between EDTA gel and EDTA solution in smear layer removal.

Ligand-enhanced electrokinetic remediation of metal-contaminated marine sediments with high acid buffering capacity.

PubMed

Masi, Matteo; Iannelli, Renato; Losito, Gabriella

2016-06-01

The suitability of electrokinetic remediation for removing heavy metals from dredged marine sediments with high acid buffering capacity was investigated. Laboratory-scale electrokinetic remediation experiments were carried out by applying two different voltage gradients to the sediment (0.5 and 0.8 V/cm) while circulating water or two different chelating agents at the electrode compartments. Tap water, 0.1 M citric acid and 0.1 M ethylenediaminetetraacetic acid (EDTA) solutions were used respectively. The investigated metals were Zn, Pb, V, Ni and Cu. In the unenhanced experiment, the acid front could not propagate due to the high acid buffering capacity of the sediments; the production of OH(-) ions at the cathode resulted in a high-pH environment causing the precipitation of CaCO3 and metal hydroxides. The use of citric acid prevented the formation of precipitates, but solubilisation and mobilisation of metal species were not sufficiently achieved. Metal removal was relevant when EDTA was used as the conditioning agent, and the electric potential was raised up to 0.8 V/cm. EDTA led to the formation of negatively charged complexes with metals which migrated towards the anode compartment by electromigration. This result shows that metal removal from sediments with high acid buffering capacity may be achieved by enhancing the electrokinetic process by EDTA addition when the acidification of the medium is not economically and/or environmentally sustainable.

Electromigration of Mn, Fe, Cu and Zn with citric acid in contaminated clay.

PubMed

Pazos, M; Gouveia, S; Sanroman, M A; Cameselle, C

2008-07-01

Metal reactivity, speciation and solubility have an important influence in its transportation through a porous matrix by electrokinetics and, therefore, they dramatically affect the removal efficiency. This work deals with the effect of solubility and transport competition among several metals (Mn, Fe, Cu and Zn) during their transport through polluted clay. The unenhancement electrokinetic treatment results in a limited removal of the tested metals because they were retained into the kaolinite sample by the penetration of the alkaline front. Metals showed a removal degree in accordance with the solubility of the corresponding hydroxide and its formation pH. In 7 days of treatment, the removal results were: 75.6% of Mn; 68.5% of Zn, 40.6% of Cu and 14.8% of Fe. In order to avoid the negative effects of the basic front generated at the cathode, two different techniques were proposed and tested: the addition of citric acid as complexing agent to the polluted kaolinite sample and the use of citric acid to control de pH on the cathode chamber. Both techniques are based on the capability of citric acid to act as a complexing and neutralizing agent. Almost complete removal of Mn, Cu and Zn was achieved when citric acid was used (as neutralizing or complexing agent). But Fe only reached 33% of removal because it formed a negatively charged complex with citrate that retarded its transportation to the cathode.

Phenotypes of gene disruptants in relation to a putative mitochondrial malate-citrate shuttle protein in citric acid-producing Aspergillus niger.

PubMed

Kirimura, Kohtaro; Kobayashi, Keiichi; Ueda, Yuka; Hattori, Takasumi

2016-09-01

The mitochondrial citrate transport protein (CTP) functions as a malate-citrate shuttle catalyzing the exchange of citrate plus a proton for malate between mitochondria and cytosol across the inner mitochondrial membrane in higher eukaryotic organisms. In this study, for functional analysis, we cloned the gene encoding putative CTP (ctpA) of citric acid-producing Aspergillus niger WU-2223L. The gene ctpA encodes a polypeptide consisting 296 amino acids conserved active residues required for citrate transport function. Only in early-log phase, the ctpA disruptant DCTPA-1 showed growth delay, and the amount of citric acid produced by strain DCTPA-1 was smaller than that by parental strain WU-2223L. These results indicate that the CTPA affects growth and thereby citric acid metabolism of A. niger changes, especially in early-log phase, but not citric acid-producing period. This is the first report showing that disruption of ctpA causes changes of phenotypes in relation to citric acid production in A. niger.

Model-based design of a pilot-scale simulated moving bed for purification of citric acid from fermentation broth.

PubMed

Wu, Jinglan; Peng, Qijun; Arlt, Wolfgang; Minceva, Mirjana

2009-12-11

One of the conventional processes used for the recovery of citric acid from its fermentation broth is environmentally harmful and cost intensive. In this work an innovative benign process, which comprises simulated moving bed (SMB) technology and use of a tailor-made tertiary poly(4-vinylpyridine) (PVP) resin as a stationary phase is proposed. This paper focuses on a model-based design of the operation conditions for an existing pilot-scale SMB plant. The SMB unit is modeled on the basis of experimentally determined hydrodynamics, thermodynamics and mass transfer characteristics in a single chromatographic column. Three mathematical models are applied and validated for the prediction of the experimentally attained breakthrough and elution profiles of citric acid and the main impurity component (glucose). The transport dispersive model was selected for the SMB simulation and design studies, since it gives a satisfactory prediction of the elution profiles within acceptable computational time. The equivalent true moving bed (TMB) and SMB models give a good prediction of the experimentally attained SMB separation performances, obtained with a real clarified and concentrated fermentation broth as a feed mixture. The SMB separation requirements are set to at least 99.8% citric acid purity and 90% citric acid recovery in the extract stream. The complete regeneration in sections 1 and 4 is unnecessary. Therefore the net flow rates in all four SMB sections have been considered in the unit design. The influences of the operating conditions (the flow rate in each section, switching time and unit configuration) on the SMB performances were investigated systematically. The resulting SMB design provides 99.8% citric acid purity and 97.2% citric acid recovery in the extract. In addition the citric acid concentration in the extract is a half of its concentration in the pretreated fermentation broth (feed).

Development of calcium phosphate cement using chitosan and citric acid for bone substitute materials.

PubMed

Yokoyama, Atsuro; Yamamoto, Satoru; Kawasaki, Takao; Kohgo, Takao; Nakasu, Masanori

2002-02-01

We developed a calcium phosphate cement that could be molded into any desired shape due to its chewing-gum-like consistency after mixing. The powder component of the cement consists of alpha-tricalcium phosphate and tetracalcium phosphate, which were made by decomposition of hydroxyapatite ceramic blocks. The liquid component consists of citric acid, chitosan and glucose solution. In this study, we used 20% citric acid (group 20) and 45% citric acid (group 45). The mechanical properties and biocompatibility of this new cement were investigated. The setting times of cements were 5.5 min, in group 20 and 6.4 min, in group 45. When incubated in physiological saline, the cements were transformed to hydroxyapatite at 3, and 6 weeks, the compressive strengths were 15.6 and 20.7 MPa, in group 45 and group 20, respectively. The inflammatory response around the cement implanted on the bone and in the subcutaneous tissue in rats was more prominent in group 45 than in group 20 at 1 week after surgery. After 4 weeks, the inflammation disappeared and the cement had bound to bone in both groups. These results indicate that this new calcium phosphate cement is a suitable bone substitute material and that the concentration of citric acid in the liquid component affects its mechanical properties and biocompatibility.

Monitoring of the fermentation media of citric acid by the trimethylsilyl derivatives of the organic acids formed.

PubMed

Ghassempour, Alireza; Nojavan, Saeed; Talebpour, Zahra; Amiri, Ali Asghar; Najafi, Nahid Mashkouri

2004-10-20

In this approach, a derivatization method is described for monitoring of organic acids in fermentation media without any separation step. The aqueous phase of fermentation media was evaporated and heated in a silylation reagent to form trimethylsilyl (TMS) derivatives. The silylated compounds are analyzed by 29Si nuclear magnetic resonance (29Si NMR) and gas chromatography-mass spectrometry (GC-MS). 29Si NMR can qualitatively monitor the components produced in the Krebs cycle. Quantification of these compounds is investigated by using selected ion monitoring mode of mass spectrometry. In this mode, mass to charge (m/z) values of their [M - 15]+ ions, which are 465, 275, 247, 221, 335, 251, and 313 of TMS derivatives of citric, alpha-ketoglutaric, succinic, fumaric, l-malic, oxaloacetic, and palmitic (as an internal standard), acids, respectively, are used. The limit of detection and the linear working range for derivatized citric acid were found to be 0.1 mg L(-1) and 10-3 x 10(4) mg L(-1). The relative standard deviation of the method for five replicates was 2.1%. The average recovery efficiency for citric acid added to culture media was approximately 97.2%. Quantitative results of GC-MS are compared with those obtained by an ultraviolet-visible method. Copyright 2004 American Chemical Society

[Effects of Citric Acid on Activation and Methylation of Mercury in the Soils of Water-Level-Fluctuating Zone of the Three Gorges.Reservoir].

PubMed

Qin, Cai-qing; Liang, Li; You, Rui; Deng, Han; Wang, Ding-yong

2015-12-01

To investigate effects of the main component of vegetation root exudates-citric acid on activation and methylation of mercury in the soil of water-level-fluctuating zone (WLFZ) of the Three Gorges Reservoir area, simulation experiments were conducted by extracting and cultivating soil with different concentrations of citric acid. The results showed that after adding citric acid, the total mercury content in leaching solution before reaching peak were higher than that of the control, and increased with the increase of citric acid concentrations. The maximum amount of mercury complexes increased initially and then reached plateaus with the percentage against the total mercury in soil of 1.03%, 1.67%, 1.99%, 2.47%, 2.68%, 2.73% and 2.73% for different citric acid concentrations (0, 1, 2, 4, 5, 6 and 8 mmol · L⁻¹). In addition, concentrations of methylmercury ( MeHg) in soil remained stable in the first 3 hours, and then increased accompanying with the increasing rate rising with the concentration of citric acid ( besides the control group) . This result indicated that citric acid probably could promote the transformation process from inorganic mercury to MeHg in soil. which increased with the concentration of citric acid.

Effects of citric acid esterification on digestibility, structural and physicochemical properties of cassava starch.

PubMed

Mei, Ji-Qiang; Zhou, Da-Nian; Jin, Zheng-Yu; Xu, Xue-Ming; Chen, Han-Qing

2015-11-15

In this study, citric acid was used to react with cassava starch in order to compare the digestibility, structural and physicochemical properties of citrate starch samples. The results indicated that citric acid esterification treatment significantly increased the content of resistant starch (RS) in starch samples. The swelling power and solubility of citrate starch samples were lower than those of native starch. Compared with native starch, a new peak at 1724 cm(-1) was appeared in all citrate starch samples, and crystalline peaks of all starch citrates became much smaller or even disappeared. Differential scanning calorimetry results indicated that the endothermic peak of citrate starches gradually shrank or even disappeared. Moreover, the citrate starch gels exhibited better freeze-thaw stability. These results suggested that citric acid esterification induced structural changes in cassava starch significantly affected its digestibility and it could be a potential method for the preparation of RS with thermal stability. Copyright © 2015 Elsevier Ltd. All rights reserved.

Experimental Investigation and Analysis of Mercerized and Citric Acid Surface Treated Bamboo Fiber Reinforced Composite

NASA Astrophysics Data System (ADS)

De, Jyotiraman; Baxi, R. N., Dr.

2017-08-01

Mercerization or NaOH fiber surface treatment is one of the most popular surface treatment processes to make the natural fibers such as bamboo fibers compatible for use as reinforcing material in composites. But NaOH being a chemical is hazardous and polluting to the nature. This paper explores the possibility of use of naturally derived citric acid for bamboo fiber surface treatment and its comparison with NaOH treated Bamboo Fiber Composites. Untreated, 2.5 wt% NaOH treated and 5 wt% citric acid treated Bamboo Fiber Composites with 5 wt% fiber content were developed by Hand Lay process. Bamboo mats made of bamboo slivers were used as reinforcing material. Mechanical and physical characterization was done to compare the effects of NaOH and citric acid bamboo fiber surface treatment on mechanical and physical properties of Bamboo Fiber Composite. The experiment data reveals that the tensile and flexural strength was found to be highest for citric acid and NaOH treated Bamboo Fiber Composite respectively. Water absorption tendency was found more than the NaOH treated Bamboo Fiber Composites. SEM micrographs used to analyze the morphology of fracture surface of tensile test specimens confirm improvement in fiber-matrix interface bonding due to surface treatment of bamboo fibers.

Effectiveness of incorporating citric acid in cassava starch edible coatings to preserve quality of Martha tomatoes

NASA Astrophysics Data System (ADS)

Ambarsari, I.; Oktaningrum, G. N.; Endrasari, R.

2018-01-01

Tomato as an agricultural product is extremely perishable. Coatings of tomatoes with edible starch extend quality and storage life of the fruits. Incorporation of citric acid as antimicrobial agent in the edible starch coatings is expected to preserve the quality of tomatoes during storage. The aim of this study was to verify the effectiveness of citric acid incorporated in cassava starch coating to preserve quality of tomatoes. The edible coatings formula consisted of cassava starch solutions (1; 2; 3%), citric acid (0.5; 1.0%) and glycerol (10%). Tomatoes were dipped to the coating solution for 10 seconds, then air-dried and stored at room temperature during 18 days. All the treatments were carried out in triplicates. Experimental data were analyzed using One Way ANOVA. The results showed that coating treatments did not affect the weight loss, moisture content, color characteristic, carotene and vitamin C content on Martha tomatoes. The low concentration of starch coating on Martha tomatoes are indicated to be the reason why there was no significant difference between coated and coated tomatoes for some parameters. However, incorporating citric acid in cassava starch-based coatings could prevent tomato fruits from firmness reduction and spoilage during storage.

Use of acetic and citric acids to inhibit Escherichia coli O157:H7, Salmonella Typhimurium and Staphylococcus aureus in tabbouleh salad.

PubMed

Al-Rousan, Walid M; Olaimat, Amin N; Osaili, Tareq M; Al-Nabulsi, Anas A; Ajo, Radwan Y; Holley, Richard A

2018-08-01

The objective of the current study was to evaluate the antimicrobial action of different concentrations of acetic (0.3% and 0.4%) or citric (1% and 1.4%) acids and their combinations (1% citric acid plus 0.4% acetic acid and 1.4% citric acid plus 0.3% acetic acid) against Salmonella Typhimurium, Escherichia coli O157:H7 and Staphylococcus aureus in tabbouleh salad stored at 21, 10 and 4 °C. Acetic acid was more inhibitory toward S. Typhimurium and E. coli O157:H7 than citric acid at 21 °C; S. Typhimurium and E. coli O157:H7 cells were not detected in tabbouleh treated with 0.4% acetic acid after 5 and 7 days, respectively. The combined effect of acetic and citric acid was synergistic against S. Typhimurium, and E. coli O157:H7, but not against S. aureus. The combinations of acetic and citric acids reduced S. Typhimurium, and E. coli O157:H7 to below the detection levels after 2 and 3 days at 21 °C, respectively. However, these treatments significantly reduced S. aureus numbers compared to the control at tested temperatures by the end of storage. Acetic and citric acids have the potential to be used in tabbouleh salad to reduce the risk from S. Typhimurium, E. coli O157:H7 and S. aureus. Copyright © 2018. Published by Elsevier Ltd.

78 FR 54625 - Citric Acid and Certain Citrate Salts From the People's Republic of China: Notice of Partial...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-05

... DEPARTMENT OF COMMERCE International Trade Administration [C-570-938] Citric Acid and Certain Citrate Salts From the People's Republic of China: Notice of Partial Rescission of Countervailing Duty... of the countervailing duty (CVD) order on citric acid and certain citrate salts from the People's...

Effects of ultraviolet irradiation on bonding strength between Co-Cr alloy and citric acid-crosslinked gelatin matrix.

PubMed

Inoue, Motoki; Sasaki, Makoto; Katada, Yasuyuki; Taguchi, Tetsushi

2014-02-01

Novel techniques for creating a strong bond between polymeric matrices and biometals are required. We immobilized polymeric matrices on the surface of biometal for drug-eluting stents through covalent bond. We performed to improve the bonding strength between a cobalt-chromium alloy and a citric acid-crosslinked gelatin matrix by ultraviolet irradiation on the surface of cobalt-chromium alloy. The ultraviolet irradiation effectively generated hydroxyl groups on the surface of the alloy. The bonding strength between the gelatin matrix and the alloy before ultraviolet irradiation was 0.38 ± 0.02 MPa, whereas it increased to 0.48 ± 0.02 MPa after ultraviolet irradiation. Surface analysis showed that the citric acid derivatives occurred on the surface of the cobalt-chromium alloy through ester bond. Therefore, ester bond formation between the citric acid derivatives active esters and the hydroxyl groups on the cobalt-chromium alloy contributed to the enhanced bonding strength. Ultraviolet irradiation and subsequent immobilization of a gelatin matrix using citric acid derivatives is thus an effective way to functionalize biometal surfaces.

76 FR 2648 - Citric Acid and Certain Citrate Salts From People's Republic of China: Extension of Time Limit...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-01-14

... DEPARTMENT OF COMMERCE International Trade Administration [C-570-938] Citric Acid and Certain Citrate Salts From People's Republic of China: Extension of Time Limit for the Preliminary Results of the... duty order on citric acid and certain citrate salts from the People's Republic of China, covering the...

Synthesis, characterization and application of lipase-conjugated citric acid-coated magnetic nanoparticles for ester synthesis using waste frying oil.

PubMed

Patel, Unisha; Chauhan, Kishor; Gupte, Shilpa

2018-04-01

In the present work, magnetic nanoparticles (MNPs) were prepared by chemical precipitation of trivalent and divalent iron ions which were functionalized using citric acid. The bacterial isolate Staphylococcus epidermidis KX781317 was isolated from oil-contaminated site. The isolate produced lipase, which was purified and immobilized on magnetic nanoparticles (MNPs) for ester synthesis from waste frying oil (WFO). The characterization of MNPs employed conventional TEM, XRD and FTIR techniques. TEM analysis of MNPs showed the particle size in the range of 20-50 nm. FTIR spectra revealed the binding of citric acid to Fe 3 O 4 and lipase on citric acid-coated MNPs. The citric acid-coated MNPs and lipase-conjugated citric acid-coated MNPs had similar XRD patterns which indicate MNPs could preserve their magnetic properties. The maximum immobilization efficiency 98.21% of lipase-containing citric acid-coated MNPs was observed at ratio 10:1 of Cit-MNPs:lipase. The pH and temperature optima for lipase conjugated with Cit-MNPs were 7 and 35 °C, respectively. Isobutanol was found to be an effective solvent for ester synthesis and 1:2 ratio of oil:alcohol observed significant for ester formation. The ester formation was determined using TLC and the % yield of ester conversion was calculated. The rate of ester formation is directly proportional to the enzyme load. Formed esters were identified as isobutyl laurate ester and isobutyl myristate ester through GC-MS analysis.

Influence of ethylenediaminetetraacetic acid (EDTA) on the on the ability of fatty acids to inhibit the growth of bacteria associated with poultry processing.

USDA-ARS?s Scientific Manuscript database

The effect of ethylenediaminetetraacetic acid (EDTA) on the bactericidal activity of alkaline salts of fatty acids was examined. A 0.5 M concentration of caproic, caprylic, capric, and lauric acids was dissolved in 1.0 M potassium hydroxide (KOH), and then supplemented with 0, 5, or 10 mM of EDTA. T...

Changes of lipid and fatty acid absorption induced by high dose of citric acid ester and lecithin emulsifiers.

PubMed

Sadouki, Mohamed; Bouchoucha, Michel

2014-09-01

To describe the effect of two food emulsifiers, lecithin (E322) and citric acid esters of mono-and diglycerides of fatty acids (E472c), on the intestinal absorption of lipids. The experiment was conducted on 24 male Wistar rats randomly assigned in three groups. For two groups of six rats, 30% of the lipid intake was replaced with lecithin (L) or citric acid ester of mono and diglycerides, (E); the remaining 12 rats were the control group (C). Diet and fecal fat analysis was used to determine the apparent lipid absorption (ALA) and fatty acids. ALA was significantly lower in the group E than in the groups C and L (p < 0.001). ALA of long saturated chain fatty acids decreased while the length of the carbon chains increased, and this decrease was higher in the group E. E472c emulsifier decreased the intestinal absorption of lipids.

Theoretical study on the mechanism of aqueous synthesis of formic acid catalyzed by [Ru3+]-EDTA complex.

PubMed

Chen, Zhe-Ning; Chan, Kwong-Yu; Pulleri, Jayasree K; Kong, Jing; Hu, Hao

2015-02-16

Because formic acid can be effectively decomposed by catalysis into very pure hydrogen gas, the synthesis of formic acid, especially using CO and H2O as an intermediate of the water gas shift reaction (WGSR), bears important application significance in industrial hydrogen gas production. Here we report a theoretical study on the mechanism of efficient preparation of formic acid using CO and H2O catalyzed by a water-soluble [Ru(3+)]-EDTA complex. To determine the feasibility of using the [Ru(3+)]-EDTA catalyst to produce CO-free hydrogen gas in WGSR, two probable reaction paths have been examined: one synthesizes formic acid, while the other converts the reactants directly into CO2 and H2, the final products of WGSR. Our calculation results provide a detailed mechanistic rationalization for the experimentally observed selective synthesis of HCOOH by the [Ru(3+)]-EDTA catalyst. The results support the applicability of using the [Ru(3+)]-EDTA catalyst to efficiently synthesize formic acid for hydrogen production. Careful analyses of the electronic structure and interactions of different reaction complexes suggest that the selectivity of the reaction processes is achieved through the proper charge/valence state of the metal center of the [Ru(3+)]-EDTA complex. With the catalytic roles of the ruthenium center and the EDTA ligand being carefully understood, the detailed mechanistic information obtained in this study will help to design more efficient catalysts for the preparation of formic acid and further to produce CO-free H2 at ambient temperature.

Effects of blanching, acidification, or addition of EDTA on vitamin C and β-carotene stability during mango purée preparation.

PubMed

Guiamba, Isabel R F; Svanberg, Ulf

2016-09-01

The impact of acidification with citric acid, addition of EDTA or water blanching at high temperature, and short time (HTST) conducted at 90°C for 4 min, on the retention of vitamin C (L-AA and DHAA) and β-carotene was studied in mango purée 30 min after crushing. HTST blanching prior to matrix disruption into purée resulted in complete inactivation of polyphenol oxidase (PPO) and minor residual activity (8%) of ascorbic acid oxidase (AAO). The retention of total vitamin C was 100% in blanched purées and in purée with EDTA and about 90% in purées at pH 3.9 and 5.0. Acidification, blanching, and addition of EDTA preserved vitamin C mainly as L-AA, while complete conversion into DHAA was observed in purée at pH 5.0. The retention of all-trans-β-carotene was between 65 and 72%, with the highest value in purée with EDTA and the lowest value in purée of blanched mango. The ratio of 13-cis-β-carotene in fresh mango was 8.2 ± 0.5% that increased significantly after blanching and in purée at pH 5.0.

NASA and ESA Collaboration on Alternative to Nitric Acid Passivation: Parameter Optimization of Citric Acid Passivation for Stainless Steel Alloys

NASA Technical Reports Server (NTRS)

Kessel, Kurt R.

2016-01-01

National Aeronautics and Space Administration (NASA) Headquarters chartered the Technology Evaluation for Environmental Risk Mitigation Principal Center (TEERM) to coordinate agency activities affecting pollution prevention issues identified during system and component acquisition and sustainment processes. The primary objectives of NASA TEERM are to: Reduce or eliminate the use of hazardous materials or hazardous processes at manufacturing, remanufacturing, and sustainment locations. Avoid duplication of effort in actions required to reduce or eliminate hazardous materials through joint center cooperation and technology sharing. Corrosion is an extensive problem that affects the National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA). The damaging effects of corrosion result in steep costs, asset downtime affecting mission readiness, and safety risks to personnel. Consequently, it is vital to reduce corrosion costs and risks in a sustainable manner. NASA and ESA have numerous structures and equipment that are fabricated from stainless steel. The standard practice for protection of stainless steel is a process called passivation. Passivation is defined by The American Heritage Dictionary of the English Language as to treat or coat (a metal) in order to reduce the chemical reactivity of its surface. Passivation works by forming a shielding outer (metal oxide) layer that reduces the impact of destructive environmental factors such as air or water. Consequently, this process necessitates a final product that is very clean and free of iron and other contaminants. Typical passivation procedures call for the use of nitric acid; however, there are a number of environmental, worker safety, and operational issues associated with its use. Citric acid is an alternative to nitric acid for the passivation of stainless steels. Citric acid offers a variety of benefits including increased safety for personnel, reduced environmental impact, and

Anti-Inflammatory Activity of Citric Acid-Treated Wheat Germ Extract in Lipopolysaccharide-Stimulated Macrophages.

PubMed

Jeong, Hee-Yeong; Choi, Yong-Seok; Lee, Jae-Kang; Lee, Beom-Joon; Kim, Woo-Ki; Kang, Hee

2017-07-10

Until recently, fermentation was the only processing used to improve the functionality of wheat germ. The release of 2,6-dimethoxy-1,4-benzoquinone (DMBQ) from hydroquinone glycosides during the fermentation process is considered a marker of quality control. Here, we treated wheat germ extract with citric acid (CWG) to release DMBQ and examined the anti-inflammatory activity of this extract using a lipopolysaccharide-activated macrophage model. Treatment of wheat germ with citric acid resulted in detectable release of DMBQ but reduced total phenolic and total flavonoid contents compared with untreated wheat germ extract (UWG). CWG inhibited secretion of the pro-inflammatory cytokines tumor necrosis factor-α, interleukin (IL)-6, and IL-12 and the synthesis of cyclooxygenase-2, while UWG only decreased IL-12 production. CWG and UWG induced high levels of anti-inflammatory IL-10 and heme oxygenase-1. CWG specifically inhibited phosphorylation of NF-κB p65 and p38 kinase at 15 min after LPS stimulation. Our study showed that citric acid treatment enhanced the anti-inflammatory activity of wheat germ extract.

Changes in transcript levels of starch hydrolysis genes and raising citric acid production via carbon ion irradiation mutagenesis of Aspergillus niger.

PubMed

Hu, Wei; Li, Wenjian; Chen, Hao; Liu, Jing; Wang, Shuyang; Chen, Jihong

2017-01-01

The filamentous ascomycete Aspergillus niger is well known for its ability to accumulate citric acid for the hydrolysis of starchy materials. To improve citric acid productivity, heavy ion beam mutagenesis was utilized to produce mutant A.niger strains with enhanced production of citric acid in this work. It was demonstrated that a mutant HW2 with high concentration of citric acid was isolated after carbon ion irradiation with the energy of 80Mev/μ, which was obvious increase higher than the original strain from liquefied corn starch as a feedstock. More importantly, with the evidence from the expression profiles of key genes and enzyme activity involved in the starch hydrolysis process between original strain and various phenotype mutants, our results confirmed that different transcript levels of key genes involving in starch hydrolysis process between original strain and mutants could be a significant contributor to different citric acid concentration in A.niger, such as, amyR and glaA, which therefore opened a new avenue for constructing genetically engineered A.niger mutants for high-yield citric acid accumulation in the future. As such, this work demonstrated that heavy ion beam mutagenesis presented an efficient alternative strategy to be developed to generate various phenotype microbe species mutants for functional genes research.

Changes in transcript levels of starch hydrolysis genes and raising citric acid production via carbon ion irradiation mutagenesis of Aspergillus niger

PubMed Central

Li, Wenjian; Chen, Hao; Liu, Jing; Wang, Shuyang; Chen, Jihong

2017-01-01

The filamentous ascomycete Aspergillus niger is well known for its ability to accumulate citric acid for the hydrolysis of starchy materials. To improve citric acid productivity, heavy ion beam mutagenesis was utilized to produce mutant A.niger strains with enhanced production of citric acid in this work. It was demonstrated that a mutant HW2 with high concentration of citric acid was isolated after carbon ion irradiation with the energy of 80Mev/μ, which was obvious increase higher than the original strain from liquefied corn starch as a feedstock. More importantly, with the evidence from the expression profiles of key genes and enzyme activity involved in the starch hydrolysis process between original strain and various phenotype mutants, our results confirmed that different transcript levels of key genes involving in starch hydrolysis process between original strain and mutants could be a significant contributor to different citric acid concentration in A.niger, such as, amyR and glaA, which therefore opened a new avenue for constructing genetically engineered A.niger mutants for high-yield citric acid accumulation in the future. As such, this work demonstrated that heavy ion beam mutagenesis presented an efficient alternative strategy to be developed to generate various phenotype microbe species mutants for functional genes research. PMID:28650980

The opposite roles of agdA and glaA on citric acid production in Aspergillus niger.

PubMed

Wang, Lu; Cao, Zhanglei; Hou, Li; Yin, Liuhua; Wang, Dawei; Gao, Qiang; Wu, Zhenqiang; Wang, Depei

2016-07-01

Citric acid is produced by an industrial-scale process of fermentation using Aspergillus niger as a microbial cell factory. However, citric acid production was hindered by the non-fermentable isomaltose and insufficient saccharification ability in A. niger when liquefied corn starch was used as a raw material. In this study, A. niger TNA 101ΔagdA was constructed by deletion of the α-glucosidase-encoding agdA gene in A. niger CGMCC 10142 genome using Agrobacterium tumefaciens-mediated transformation. The transformants A. niger OG 1, OG 17, and OG 31 then underwent overexpression of glucoamylase in A. niger TNA 101ΔagdA. The results showed that the α-glucosidase activity of TNA 101ΔagdA was decreased by 62.5 % compared with CGMCC 10142, and isomaltose was almost undetectable in the fermentation broth. The glucoamylase activity of the transformants OG 1 and OG 17 increased by 34.5 and 16.89 % compared with that of TNA 101ΔagdA, respectively. In addition, for the recombinants TNA 101ΔagdA, OG 1 and OG 17, there were no apparent defects in the growth development. Consequently, in comparison with CGMCC 10142, TNA 101ΔagdA and OG 1 decreased the residual reducing sugar by 52.95 and 88.24 %, respectively, and correspondingly increased citric acid production at the end of fermentation by 8.68 and 16.87 %. Citric acid production was further improved by decreasing the non-fermentable residual sugar and increasing utilization rate of corn starch material in A. niger. Besides, the successive saccharification and citric acid fermentation processes were successfully integrated into one step.

Deletion of a Chitin Synthase Gene in a Citric Acid Producing Strain of Aspergillus niger

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rinker, Torri E.; Baker, Scott E.

Citric acid production by the filamentous fungus Aspergillus niger is carried out in a process that causes the organism to drastically alter its morphology. This altered morphology includes hyphal swelling and highly limited polar growth resulting in clumps of swollen cells that eventually aggregate into pellets of approximately 100 microns in diameter. In this pelleted form, A. niger has increased citric acid production as compared to growth in filamentous form. Chitin is a crucial component of the cell wall of filamentous fungi. Alterations in the deposition or production of chitin may have profound effects on the morphology of the organism.more » In order to study the role of chitin synthesis in pellet formation we have deleted a chitin synthase gene (csmA) in Aspergillus niger strain ATCC 11414 using a PCR based deletion construct. This class of chitin synthases is only found in filamentous fungi and is not present in yeasts. The csmA genes contain a myosin motor domain at the N-terminus and a chitin synthesis domain at the C-terminus. They are believed to contribute to the specialized polar growth observed in filamentous fungi that is lacking in yeasts. The csmA deletion strain (csmAΔ) was subjected to minimal media with and without osmotic stabilizers as well as tested in citric acid production media. Without osmotic stabilizers, the mutant germlings were abnormally swollen, primarily in the subapical regions, and contained large vacuoles. However, this swelling is ultimately not inhibitory to growth as the germlings are able to recover and undergo polar growth. Colony formation was largely unaffected in the absence of osmotic stabilizers. In citric acid production media csmAΔ was observed to have a 2.5 fold increase in citric acid production. The controlled expression of this class of chitin synthases may be useful for improving production of organic acids in filamentous fungi.« less

Accelerated anaerobic dechlorination of DDT in slurry with Hydragric Acrisols using citric acid and anthraquinone-2,6-disulfonate (AQDS).

PubMed

Liu, Cuiying; Xu, Xianghua; Fan, Jianling

2015-12-01

The application of electron donor and electron shuttle substances has a vital influence on electron transfer, thus may affect the reductive dechlorination of 1,1,1-trichoro-2,2-bis(p-chlorophenyl)ethane (DDT) in anaerobic reaction systems. To evaluate the roles of citric acid and anthraquinone-2,6-disulfonate (AQDS) in accelerating the reductive dechlorination of DDT in Hydragric Acrisols that contain abundant iron oxide, a batch anaerobic incubation experiment was conducted in a slurry system with four treatments of (1) control, (2) citric acid, (3) AQDS, and (4) citric acid+AQDS. Results showed that DDT residues decreased by 78.93%-92.11% of the initial quantities after 20days of incubation, and 1,1-dichloro-2,2-bis(4-chlorophenyl)-ethane (DDD) was the dominant metabolite. The application of citric acid accelerated DDT dechlorination slightly in the first 8days, while the methanogenesis rate increased quickly, and then the acceleration effect improved after the 8th day while the methanogenesis rate decreased. The amendment by AQDS decreased the Eh value of the reaction system and accelerated microbial reduction of Fe(III) oxides to generate Fe(II), which was an efficient electron donor, thus enhancing the reductive dechlorination rate of DDT. The addition of citric acid+AQDS was most efficient in stimulating DDT dechlorination, but no significant interaction between citric acid and AQDS on DDT dechlorination was observed. The results will be of great significance for developing an efficient in situ remediation strategy for DDT-contaminated sites. Copyright © 2015. Published by Elsevier B.V.

Phytotoxicity of citric acid and Tween® 80 for potential use as soil amendments in enhanced phytoremediation.

PubMed

Agnello, A C; Huguenot, D; van Hullebusch, E D; Esposito, G

2015-01-01

Enhanced phytoremediation adding biodegradable amendments like low molecular weight organic acids and surfactants is an interesting area of current research to overcome the limitation that represents low bioavailability of pollutants in soils. However, prior to their use in assisted phytoremediation, it is necessary to test if amendments per se exert any toxic effect to plants and to optimize their application mode. In this context, the present study assessed the effects of citric acid and Tween® 80 (polyethylene glycol sorbitan monooleate) on the development of alfalfa (Medicago sativa) plants, as influenced by their concentration and frequency of application, in order to evaluate the feasibility for their future use in enhanced phytoremediation of multi-contaminated soils. The results showed that citric acid negatively affected plant germination, while it did not have any significant effect on biomass or chlorophyll content. In turn, Tween® 80 did not affect plant germination and showed a trend to increase biomass, as well as it did not have any significant effect on chlorophyll levels. M. sativa appeared to tolerate citric acid and Tween® 80 at the tested concentrations, applied weekly. Consequently, citric acid and Tween® 80 could potentially be utilized to assist phytoremediation of contaminated soils vegetated with M. sativa.

Overexpression of a C4-dicarboxylate transporter is the key for rerouting citric acid to C4-dicarboxylic acid production in Aspergillus carbonarius.

PubMed

Yang, Lei; Christakou, Eleni; Vang, Jesper; Lübeck, Mette; Lübeck, Peter Stephensen

2017-03-14

C 4 -dicarboxylic acids, including malic acid, fumaric acid and succinic acid, are valuable organic acids that can be produced and secreted by a number of microorganisms. Previous studies on organic acid production by Aspergillus carbonarius, which is capable of producing high amounts of citric acid from varieties carbon sources, have revealed its potential as a fungal cell factory. Earlier attempts to reroute citric acid production into C 4 -dicarboxylic acids have been with limited success. In this study, a glucose oxidase deficient strain of A. carbonarius was used as the parental strain to overexpress a native C 4 -dicarboxylate transporter and the gene frd encoding fumarate reductase from Trypanosoma brucei individually and in combination. Impacts of the introduced genetic modifications on organic acid production were investigated in a defined medium and in a hydrolysate of wheat straw containing high concentrations of glucose and xylose. In the defined medium, overexpression of the C 4 -dicarboxylate transporter alone and in combination with the frd gene significantly increased the production of C 4 -dicarboxylic acids and reduced the accumulation of citric acid, whereas expression of the frd gene alone did not result in any significant change of organic acid production profile. In the wheat straw hydrolysate after 9 days of cultivation, similar results were obtained as in the defined medium. High amounts of malic acid and succinic acid were produced by the same strains. This study demonstrates that the key to change the citric acid production into production of C 4 -dicarboxylic acids in A. carbonarius is the C 4 -dicarboxylate transporter. Furthermore it shows that the C 4 -dicarboxylic acid production by A. carbonarius can be further increased via metabolic engineering and also shows the potential of A. carbonarius to utilize lignocellulosic biomass as substrates for C 4 -dicarboxylic acid production.

Improving Properties of Arrowroot Starch (Maranta arundinacea)/PVA Blend Films by Using Citric Acid as Cross-linking Agent

NASA Astrophysics Data System (ADS)

Sholichah, Enny; Purwono, Bambang; Nugroho, Pramono

2017-12-01

This research studied the effect of PVA as organic polymer and citric acid as crosslinker agent in the arrowroot starch/PVA blend films. The properties of films were investigated by water uptake, water vapor permeability, mechanical properties, thermal stability, spectra of FTIR and XRD patterns. PVA used in this research influenced the film properties at the highest concentration. The cross-linkingsinter or intra molecules of arrowroot and PVA were developed as ester bonds which are formed from the reaction of hydroxyl groups consisting of starch and PVA with citric acid. The ester bond was confirmed by FTIR spectra. The increase of the amount of citric acid affected significantly on physical, chemical and mechanical properties, water uptake, WVP and crystallinity. Water barrier level was reduced by decreasing of water uptake and WVP succeeded significantly with increased crosslinking. Cross-linking impact the thermal stability of the films. The elasticity of the films also increases the production of citric acid as a plasticizer in the making of the films as a food packaging material.

Quantitative GC-MS assay of citric acid from humans and db/db mice blood serum to assist the diagnosis of diabetic nephropathy.

PubMed

Gao, Haoxue; Yu, Xiaoyi; Sun, Runbin; Yang, Na; He, Jun; Tao, Mingxue; Gu, Huilin; Yan, Caixia; Aa, Jiye; Wang, Guangji

2018-03-01

The early diagnosis of diabetic nephropathy (DN) is rather challenging. Our previous study suggested that citric acid is a potential marker for the early diagnosis of diabetic nephropathy in db/db mice. For the first time, in this study, a surrogate analyte of 13 C 6 -citric acid was employed to generate calibration curves for the quantitative measurement of the endogenous citric acid in the sera of db/db mice and diabetic nephropathy patients by GC/MS after the analytes were extracted, methoximated and trimethylsilylated. The constant response factor of 13 C 6 -citric acid versus citric acid over the linear range indicated the identical ionization efficiency of these two compounds. The full validation assessments suggested that the method is sensitive, specific, reliable, reproducible and has acceptable parameters. Statistical analysis revealed cut-off citric acid concentrations of 29.24 μg/mL with a 95% confidence interval between 32.75 and 39.16 μg/mL in the diabetic nephropathy patients and 16.74 and 22.57 μg/mL in the normal controls. The areas under the receiver operating characteristic curves indicated accuracies of over 90% for the diagnoses of early diabetic nephropathy in both humans and db/db mice, which suggests that the serum citric acid level is potentially a biomarker that could assist in the diagnosis of diabetic nephropathy. Copyright © 2018 Elsevier B.V. All rights reserved.

Modification of wheat gluten with citric acid to produce superabsorbent materials

USDA-ARS?s Scientific Manuscript database

Wheat gluten was reacted with citric acid to produce natural superabsorbent materials able to absorb up to 78 times its weight in water. The properties of the modified gluten samples were characterized using Fourier Transform Infra-red (FTIR) spectroscopy, thermogravimetric analysis, and water uptak...

Citric acid metabolism in hetero- and homofermentative lactic acid bacteria.

PubMed Central

Drinan, D F; Robin, S; Cogan, T M

1976-01-01

The effect of citrate on production of diacetyl and acetoin by four strains each of heterofermentative and homofermentative lactic acid bacteria capable of utilizing citrate was studied. Acetoin was quantitatively the more important compound. The heterofermentative bacteria produced no acetoin or diacetyl in the absence of citrate, and two strains produced traces of acetoin in its presence. Citrate stimulated the growth rate of the heterofermentative lactobacilli. Acidification of all heterofermentative cultures with citric acid resulted in acetoin production. Destruction of accumulated acetoin appeared to coincide with the disappearance of citrate. All homofermentative bacteria produced more acetoin and diacetyl in the presence of citrate than in its absence. Citrate utilization was begun immediately by the streptococci but was delayed until at least the middle of the exponential phase in the case of the lactobacilli. PMID:5054

Chemical modification of chitosan film via surface grafting of citric acid molecular to promote the biomineralization

NASA Astrophysics Data System (ADS)

Liu, Yang; Shen, Xin; Zhou, Huan; Wang, Yingjun; Deng, Linhong

2016-05-01

We develop a novel chitosan-citric acid film (abbreviated as CS-CA) suitable for biomedical applications in this study. In this CS-CA film, the citric acid, which is a harmless organic acid has been extensively investigated as a modifying agent on carbohydrate polymers, was cross-linked by 1-Ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) onto the surface of chitosan (CS) film. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) confirms the graft copolymerization of the modified chitosan film (CS-CA). Surface wettability, moisturizing performance, the capacity of mineralization in vitro and biocompatibility of the films were characterized. After modification, this CS-CA film has good hydrophilicity. It is very evident that the citric acid grafting treatment significantly promotes the biomineralization of the chitosan based substrates. Cell experiments show that the MC3T3-E1 osteoblasts can adhere and proliferate well on the surface of CS-CA film. This CS-CA film, which can be prepared in large quantities and at low cost, should have potential application in bone tissue engineering.

Stoichiometry of Reducing Equivalents and Splitting of Water in the Citric Acid Cycle.

ERIC Educational Resources Information Center

Madeira, Vitor M. C.

1988-01-01

Presents a solution to the problem of finding the source of extra reducing equivalents, and accomplishing the stoichiometry of glucose oxidation reactions. Discusses the citric acid cycle and glycolysis. (CW)

A Calcium Enterolith in a Patient with Crohn's Disease and Its In Vitro Dissolubility in Citric Acid

PubMed Central

Urata, Haruo; Ohmori, Masayasu; Kondo, Yoshitaka; Kawahara, Yoshiro; Okada, Hiroyuki

2017-01-01

The microstructure and dissolubility of a calcified enterolith and enterolith pieces removed from a 26-year-old Japanese woman with Crohn's disease were analyzed using scanning electron microscopy and energy dispersive X-ray spectroscopy. The enterolith showed a multilayered structure with fatty acid calcium and magnesium phosphate. The amount of calcium, magnesium, and phosphate decreased after they were immersed in a citric acid solution, suggesting a potential contribution of acidic aqueous solution to elute inorganic substances contained in calcified enteroliths. This is the first study to investigate the in vitro dissolubility of calcified enteroliths induced by citric acid solution. PMID:29082049

Intake of Ethanol, Sodium Chloride, Sucrose, Citric Acid, and Quinine Hydrochloride Solutions by Mice: A Genetic Analysis

PubMed Central

Bachmanov, A. A.; Reed, D. R.; Tordoff, M. G.; Price, R. A.; Beauchamp, G. K.

2013-01-01

Mice of the 129/J (129) and C57BL/6ByJ (B6) strains and their reciprocal F1 and F2 hybrids were offered solutions of ethanol, sucrose, citric acid, quinine hydrochloride, and NaCI in two-bottle choice tests. Consistent with earlier work, the B6 mice drank more ethanol, sucrose, citric acid, and quinine hydrochloride solution and less NaCI solution than did 129 mice. Analyses of each generation’s means and distributions showed that intakes of ethanol, quinine, sucrose, and NaCI were influenced by a few genes. The mode of inheritance was additive in the case of ethanol and quinine, for sucrose the genotype of the 129 strain was recessive, and for NaCI it was dominant. Citric acid intake appeared to be influenced by many genes with small effects, with the 129 genotype dominant. Correlations of sucrose consumption with ethanol and citric acid consumption were found among mice of the F2 generation, and the genetically determined component of these correlations was stronger than the component related to environmental factors. The genetically determined correlation between sucrose and ethanol intakes is consistent with the hypothesis that the higher ethanol intake by B6 mice depends, in part, on higher hedonic attractiveness of its sweet taste component. PMID:8990535

A Biodegradable Thermoset Polymer Made by Esterification of Citric Acid and Glycerol

PubMed Central

Halpern, Jeffrey M.; Urbanski, Richard; Weinstock, Allison K.; Iwig, David F.; Mathers, Robert T.; von Recum, Horst

2014-01-01

A new biomaterial, a degradable thermoset polymer, was made from simple, economical, biocompatable monomers without the need for a catalyst. Glycerol and citric acid, non-toxic and renewable reagents, were crosslinked by a melt polymerization reaction at temperatures from 90-150°C. Consistent with a condensation reaction, water was determined to be the primary byproduct. The amount of crosslinking was controlled by the reaction conditions, including temperature, reaction time, and ratio between glycerol and citric acid. Also, the amount of crosslinking was inversely proportional to the rate of degradation. As a proof-of-principle for drug delivery applications, gentamicin, an antibiotic, was incorporated into the polymer with preliminary evaluations of antimicrobial activity. The polymers incorporating gentamicin had significantly better bacteria clearing of Staphylococcus aureus compared to non-gentamicin gels for up to nine days. PMID:23737239

Citric acid induces cell-cycle arrest and apoptosis of human immortalized keratinocyte cell line (HaCaT) via caspase- and mitochondrial-dependent signaling pathways.

PubMed

Ying, Tsung-Ho; Chen, Chia-Wei; Hsiao, Yu-Ping; Hung, Sung-Jen; Chung, Jing-Gung; Yang, Jen-Hung

2013-10-01

Citric acid is an alpha-hydroxyacid (AHA) widely used in cosmetic dermatology and skincare products. However, there is concern regarding its safety for the skin. In this study, we investigated the cytotoxic effects of citric acid on the human keratinocyte cell line HaCaT. HaCaT cells were treated with citric acid at 2.5-12.5 mM for different time periods. Cell-cycle arrest and apoptosis were investigated by 4,6-diamidino-2-phenylindole dihydrochloride (DAPI) staining, flow cytometry, western blot and confocal microscopy. Citric acid not only inhibited proliferation of HaCaT cells in a dose-dependent manner, but also induced apoptosis and cell cycle-arrest at the G2/M phase (before 24 h) and S phase (after 24 h). Citric acid increased the level of Bcl-2-associated X protein (BAX) and reduced the levels of B-cell lymphoma-2 (BCL-2), B-cell lymphoma-extra large (BCL-XL) and activated caspase-9 and caspase-3, which subsequently induced apoptosis via caspase-dependent and caspase-independent pathways. Citric acid also activated death receptors and increased the levels of caspase-8, activated BH3 interacting-domain death agonist (BID) protein, Apoptosis-inducing factor (AIF), and Endonuclease G (EndoG). Therefore, citric acid induces apoptosis through the mitochondrial pathway in the human keratinocyte cell line HaCaT. The study results suggest that citric acid is cytotoxic to HaCaT cells via induction of apoptosis and cell-cycle arrest in vitro.

Functional and in vitro gastric digestibility of the whey protein hydrogel loaded with nanostructured lipid carriers and gelled via citric acid-mediated crosslinking.

PubMed

Hashemi, Behnaz; Madadlou, Ashkan; Salami, Maryam

2017-12-15

Nanostructured lipid carriers (NLCs) with mean size of 347nm were fabricated and added into a heat-denatured whey protein solution. The subsequent crosslinking of proteins by citric acid or CaCl 2 resulted in the formation of cold-set hydrogels. Fourier transform infrared spectroscopy (FTIR) proposed formation of more hydrogen bonds in gel due to NLC loading or citric acid-mediated gelation. It was also found based on FITR spectroscopy that citric acid crosslinking disordered whey proteins. Scanning electron microscopy (SEM) imaging showed a non-porous and finely meshed microstructure for the crosslinked gels compared to non-crosslinked counterparts. Crosslinking also increased the firmness and water-holding capacity of gels. In pepsin-free fluid, a strong correlation existed between reduction in gel swellability and digestibility over periods up to 60min due to NLC loading and citric acid gelation. However, in peptic fluid, NLC loading and citric acid crosslinking brought about much higher decrease in digestibility than swellability. Copyright © 2017 Elsevier Ltd. All rights reserved.

Contamination of lithium heparin blood by K2-ethylenediaminetetraacetic acid (EDTA): an experimental evaluation

PubMed Central

Lima-Oliveira, Gabriel; Salvagno, Gian Luca; Danese, Elisa; Brocco, Giorgio; Guidi, Gian Cesare; Lippi, Giuseppe

2014-01-01

Introduction: The contamination of serum or lithium heparin blood with ethylenediaminetetraacetic acid (EDTA) salts may affect accuracy of some critical analytes and jeopardize patient safety. The aim of this study was to evaluate the effect of lithium heparin sample contamination with different amounts of K2EDTA. Materials and methods: Fifteen volunteers were enrolled among the laboratory staff. Two lithium heparin tubes and one K2EDTA tube were collected from each subject. The lithium-heparin tubes of each subject were pooled and divided in 5 aliquots. The whole blood of K2EDTA tube was then added in scalar amount to autologous heparinised aliquots, to obtained different degrees of K2EDTA blood volume contamination (0%; 5%; 13%; 29%; 43%). The following clinical chemistry parameters were then measured in centrifuged aliquots: alanine aminotranspherase (ALT), bilirubin (total), calcium, chloride, creatinine, iron, lactate dehydrogenase (LD), lipase, magnesium, phosphate, potassium, sodium. Results: A significant variation starting from 5% K2EDTA contamination was observed for calcium, chloride, iron, LD, magnesium (all decreased) and potassium (increased). The variation of phosphate and sodium (both increased) was significant after 13% and 29% K2EDTA contamination, respectively. The values of ALT, bilirubin, creatinine and lipase remained unchanged up to 43% K2EDTA contamination. When variations were compared with desirable quality specifications, the bias was significant for calcium, chloride, LD, magnesium and potassium (from 5% K2EDTA contamination), sodium, phosphate and iron (from 29% K2EDTA contamination). Conclusions: The concentration of calcium, magnesium, potassium, chloride and LD appears to be dramatically biased by even modest K2EDTA contamination (i.e., 5%). The values of iron, phosphate, and sodium are still reliable up to 29% K2EDTA contamination, whereas ALT, bilirubin, creatinine and lipase appear overall less vulnerable towards K2EDTA

Contamination of lithium heparin blood by K2-ethylenediaminetetraacetic acid (EDTA): an experimental evaluation.

PubMed

Lima-Oliveira, Gabriel; Salvagno, Gian Luca; Danese, Elisa; Brocco, Giorgio; Guidi, Gian Cesare; Lippi, Giuseppe

2014-01-01

The contamination of serum or lithium heparin blood with ethylenediaminetetraacetic acid (EDTA) salts may affect accuracy of some critical analytes and jeopardize patient safety. The aim of this study was to evaluate the effect of lithium heparin sample contamination with different amounts of K2EDTA. Fifteen volunteers were enrolled among the laboratory staff. Two lithium heparin tubes and one K2EDTA tube were collected from each subject. The lithium-heparin tubes of each subject were pooled and divided in 5 aliquots. The whole blood of K2EDTA tube was then added in scalar amount to autologous heparinised aliquots, to obtained different degrees of K2EDTA blood volume contamination (0%; 5%; 13%; 29%; 43%). The following clinical chemistry parameters were then measured in centrifuged aliquots: alanine aminotranspherase (ALT), bilirubin (total), calcium, chloride, creatinine, iron, lactate dehydrogenase (LD), lipase, magnesium, phosphate, potassium, sodium. A significant variation starting from 5% K2EDTA contamination was observed for calcium, chloride, iron, LD, magnesium (all decreased) and potassium (increased). The variation of phosphate and sodium (both increased) was significant after 13% and 29% K2EDTA contamination, respectively. The values of ALT, bilirubin, creatinine and lipase remained unchanged up to 43% K2EDTA contamination. When variations were compared with desirable quality specifications, the bias was significant for calcium, chloride, LD, magnesium and potassium (from 5% K2EDTA contamination), sodium, phosphate and iron (from 29% K2EDTA contamination). The concentration of calcium, magnesium, potassium, chloride and LD appears to be dramatically biased by even modest K2EDTA contamination (i.e., 5%). The values of iron, phosphate, and sodium are still reliable up to 29% K2EDTA contamination, whereas ALT, bilirubin, creatinine and lipase appear overall less vulnerable towards K2EDTA contamination.

EDTA retention and emissions from remediated soil.

PubMed

Jez, Erika; Lestan, Domen

2016-05-01

EDTA-based remediation is reaching maturity but little information is available on the state of chelant in remediated soil. EDTA soil retention was examined after extracting 20 soil samples from Pb contaminated areas in Slovenia, Austria, Czech Republic and USA with 120 mM kg(-1) Na2H2EDTA, CaNa2EDTA and H4EDTA for 2 and 24 h. On average, 73% of Pb was removed from acidic and 71% from calcareous soils (24 h extractions). On average, 15% and up to 64% of applied EDTA was after remediation retained in acidic soils. Much less; in average 1% and up to the 22% of EDTA was retained in calcareous soils. The secondary emissions of EDTA retained in selected remediated soil increased with the acidity of the media: the TCLP (Toxicity Characteristic Leaching Procedure) solution (average pH end point 3.6) released up to 36% of EDTA applied in the soil (28.1 mmol kg(-1)). Extraction with deionised water (pH > 6.0) did not produce measurable EDTA emissions. Exposing soil to model abiotic (thawing/freezing cycles) and biotic (ingestion by earthworms Lumbricus rubellus) ageing factors did not induce additional secondary emissions of EDTA retained in remediated soil. Copyright © 2016 Elsevier Ltd. All rights reserved.

Synthesis and characterization of hydrogel films of carboxymethyl tamarind gum using citric acid.

PubMed

Mali, Kailas K; Dhawale, Shashikant C; Dias, Remeth J

2017-12-01

The objective of this study was to synthesize and characterize citric acid crosslinked carboxymethyl tamarind gum (CMTG) hydrogels films. The hydrogel films were characterized by Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, solid state 13 C-nuclear magnetic resonance ( 13 C NMR) spectroscopy and differential scanning calorimeter (DSC). The prepared hydrogel films were evaluated for the carboxyl content and swelling ratio. The model drug moxifloxacin hydrochloride was loaded into hydrogels films and drug release was studied at pH 7.4. The hemolysis assay was used to study the biocompatibility of hydrogel films. The results of ATR-FTIR, solid state 13 C NMR and DSC confirmed the formation of ester crosslinks between citric acid and CMTG. The total carboxyl content of hydrogel film was found to be decreased when amount of CMTG was increased. The swelling of hydrogel film was found to be decreased with increase in curing temperature and time. CMTG hydrogel films showed high drug loading with non-Fickian release mechanism suggesting controlled release of drug. The hydrogel films were found to be biocompatible. It can be concluded that the citric acid can be used for the preparation of CMTG hydrogel films. Further, CMTG hydrogel film can be used potentially for controlled release of drug. Copyright © 2017 Elsevier B.V. All rights reserved.

Controlling of dielectrical properties of hydroxyapatite by ethylenediamine tetraacetic acid (EDTA) for bone healing applications

NASA Astrophysics Data System (ADS)

Kaygili, Omer; Ates, Tankut; Keser, Serhat; Al-Ghamdi, Ahmed A.; Yakuphanoglu, Fahrettin

2014-08-01

The hydroxyapatite (HAp) samples in the presence of various amounts of ethylenediamine tetraacetic acid (EDTA) were prepared by sol-gel method. The effects of EDTA on the crystallinity, phase structure, chemical, micro-structural and dielectric properties of HAp samples were investigated. With the addition of EDTA, the average crystallite size of the HAp samples is gradually decreased from 30 to 22 nm and the crystallinity is in the range of 65-71%. The values of the lattice parameters (a and c) and volume of the unit cell are decreased by stages with the addition of EDTA. The dielectric parameters such as relative permittivity, dielectric loss and relaxation time are affected by the adding of EDTA. The alternating current conductivity of the as-synthesized hydroxyapatites increases with the increasing frequency and obeys the universal power law behavior. The HAp samples exhibit a non-Debye relaxation mechanism. The obtained results that the dielectrical parameters of the HAp sample can be controlled by EDTA.

Photodynamic therapy with 5-aminoolevulinic acid-induced porphyrins and DMSO/EDTA for basal cell carcinoma

NASA Astrophysics Data System (ADS)

Warloe, Trond; Peng, Qian; Heyerdahl, Helen; Moan, Johan; Steen, Harald B.; Giercksky, Karl-Erik

1995-03-01

Seven hundred sixty three basal cell carcinomas (BCCs) in 122 patients were treated by photodynamic therapy by 5-aminolevulinic acid (ALA) in cream topically applied, either alone, in combination with dimethyl sulphoxide (DMSO) and ethylenediaminetetraacetic acid disodium salt (EDTA), or with DMSO as a pretreatment. After 3 hours cream exposure 40 - 200 Joules/cm2 of 630 nm laser light was given. Fluorescence imaging of biopsies showed highly improved ALA penetration depth and doubled ALA-induced porphyrin production using DMSO/EDTA. Treatment response was recorded after 3 months. After a single treatment 90% of 393 superficial lesions responded completely, independent of using DMSO/EDTA. In 363 nodulo-ulcerative lesions the complete response rate increased from 67% to above 90% with DMSO/EDTA for lesions less than 2 mm thickness and from 34% to about 50% for lesions thicker than 2 mm. Recurrence rate observed during a follow-up period longer than 12 months was 2 - 5%. PDT of superficial thin BCCs with ALA-induced porphyrins and DMSO/EDTA equals surgery and radiotherapy with respect to cure rate and recurrence. Cosmetic results of ALA-based PDT seemed to be better than those after other therapies. In patients with the nevoid BCC syndrome the complete response rate after PDT was far lower.

EDTA and hydrochloric acid effects on mercury accumulation by Lupinus albus.

PubMed

Rodríguez, Luis; Alonso-Azcárate, Jacinto; Villaseñor, José; Rodríguez-Castellanos, Laura

2016-12-01

The efficiency of white lupine (Lupinus albus) to uptake and accumulate mercury from a soil polluted by mining activities was assessed in a pot experiment with chemically assisted phytoextraction. The mobilizing agents tested were ethylenediaminetetracetic acid (EDTA) and hydrochloric acid (HCl). Two doses of each amendment were used (0.5 and 1.0 g of amendment per kg of soil), and unamended pots were used as a control. Addition of HCl to the soil did not negatively affect plant biomass, while the use of EDTA led to a significant decrease in plant growth when compared to that found for non-treated pots, with plants visually showing symptoms of toxicity. The addition of hydrochloric acid increased root, shoot and total plant Hg uptake of white lupine by 3.7 times, 3.1 times and 3.5 times, respectively, in relation to non-amended plants. The greatest efficiency was obtained for the highest HCl dose. EDTA led to higher concentrations of total plant Hg than that found with the control, but, due to the aforementioned decrease in plant biomass, the Hg phytoextraction yield was not significantly increased. These results were attributed to the capability of both amendments to form stable Hg complexes. The concentration of Hg in the water of the soil pores after the phytoextraction experiment was very low for all treatments, showing that risks derived from metal leaching could be partially avoided by using doses and chemicals suitable to the concentration of metal in the soil and plant performance.

D-stat culture for studying the metabolic shifts from oxidative metabolism to lipid accumulation and citric acid production in Yarrowia lipolytica.

PubMed

Ochoa-Estopier, Abril; Guillouet, Stéphane E

2014-01-20

Lipid accumulation in oleaginous yeasts is triggered by nutrient imbalance in the culture medium between the carbon source in excess and the nitrogen source in limiting concentration. However Yarrowia lipolytica when cultivated on glucose as the sole carbon source, mainly produces citric acid upon nitrogen limitation over lipid accumulation (only 5-10% triacylglycerol). Therefore for developing bioprocess for the production of triacylglycerol from renewable carbon source as glucose it is of first importance to control this imbalance in order to avoid citric acid production during TAG accumulation. Using D-stat cultivation system, where the N/C was linearly decreased using a constant change rate we were able to identify the N/C ratio inducing TAG accumulation (0.085NmolCmol(-1)) and citric acid (0.021NmolCmol(-1)). We therefore demonstrated that it was possible to accumulate lipids without excretion citric acid as long as the N/C was within this indicated range. Moreover enzyme specific activities measurement during the D-stat indicated that ATP-citrate lyase, malic enzyme and acetyl-coA carboxylase were strongly induced at the onset of lipid accumulation and showed different patterns when citric acid was excreted. Our results give relevant information for future industrial bioprocess development concerning the production of lipids using renewable carbohydrate substrates as an alternative way to produce synthons for fuel or chemical industry. By controlling the N/C over the fermentation process on glucose Y. lipolytica can accumulate lipids without excreting citric acid. Copyright © 2013 Elsevier B.V. All rights reserved.

21. Interior view of citric acid air pollution control room ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

21. Interior view of citric acid air pollution control room (also known as scrubber room) in Components Test Laboratory (T-27), looking southeast. Photograph shows upgraded instrumentation, piping, tanks, and technological modifications installed in 1997-99 to accommodate component testing requirements for the Atlas V missile. - Air Force Plant PJKS, Systems Integration Laboratory, Components Test Laboratory, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

Inactivation of Foot-and-Mouth Disease Virus by Citric Acid and Sodium Carbonate with Deicers

PubMed Central

Hong, Jang-Kwan; You, Su-Hwa; Kim, Su-Mi; Tark, Dongseob; Lee, Hyang-Sim; Ko, Young-Joon; Seo, Min-Goo; Park, Jong-Hyeon; Kim, Byounghan

2015-01-01

Three out of five outbreaks of foot-and-mouth disease (FMD) since 2010 in the Republic of Korea have occurred in the winter. At the freezing temperatures, it was impossible to spray disinfectant on the surfaces of vehicles, roads, and farm premises because the disinfectant would be frozen shortly after discharge and the surfaces of the roads or machines would become slippery in cold weather. In this study, we added chemical deicers (ethylene glycol, propylene glycol, sodium chloride, calcium chloride, ethyl alcohol, and commercial windshield washer fluid) to keep disinfectants (0.2% citric acid and 4% sodium carbonate) from freezing, and we tested their virucidal efficacies under simulated cold temperatures in a tube. The 0.2% citric acid could reduce the virus titer 4 logs at −20°C with all the deicers. On the other hand, 4% sodium carbonate showed little virucidal activity at −20°C within 30 min, although it resisted being frozen with the function of the deicers. In conclusion, for the winter season, we may recommend the use of citric acid (>0.2%) diluted in 30% ethyl alcohol or 25% sodium chloride solvent, depending on its purpose. PMID:26319879

Effect of citric acid on material properties of ZnGa2O4:Cr3+ nanopowder prepared by sol-gel method

NASA Astrophysics Data System (ADS)

Hussen, Megersa K.; Dejene, Francis B.; Gonfa, Girma G.

2018-05-01

This paper reports the material properties of Cr3+ (1.0 mol%)-doped ZnGa2O4 nanopowders prepared by citric acid-assisted sol-gel method with metal cations (Zn + Ga) to citric (M:CA) molar ratios of (1:0.5, 1:1, 1:3 and 1:4). The X-ray diffraction (XRD) results show that the synthesized nanoparticles are cubic structured and concentration of citric acid did not affect the structure. The scanning electron microscope (SEM) shows that the increase of the M:CA molar ratio favors the formation of smaller nano particle of ZnGa2O4:Cr3+. The photoluminescence (PL) is found to be maximum for sample with M:CA ratio of 1:1. Further increase in citric acid leads to significant decrease in the PL intensity. Energy-dispersive X-ray spectroscopy (EDS) measurement confirms the presence of the Zn, Ga, O and Cr ions. Ultraviolet-visible (UV-Vis) spectrophotometer measurement shows an increase in reflectance in visible region and the energy band gap was found to decrease with an increase in citric acid molar ratio. The emission spectra, particle size and photoluminescence lifetimes are comparable with reports on bioimaging applications.

DNAPL remediation with in situ chemical oxidation using potassium permanganate - Part I. Mineralogy of Mn oxide and its dissolution in organic acids

NASA Astrophysics Data System (ADS)

Li, X. David; Schwartz, Franklin W.

2004-01-01

Previous studies on in situ chemical oxidation of trichloroethylene (TCE) with potassium permanganate indicated that the solid reaction product, Mn oxide, could reduce the permeability of the porous medium and impact the success of dense non-aqueous phase liquid (DNAPL) removal. In order to address the issue of permeability reduction caused by precipitation, this study investigated the mineralogy of Mn oxides and the possibilities of removing the solid precipitates by dissolution. The solid reaction product from the oxidation of TCE by permanganate is semi-amorphous potassium-rich birnessite, which has a layered mineral structure with an interlayer spacing of 7.3 Å. The chemical formula is K 0.854Mn 1.786O 4·1.55H 2O. It has a relatively small specific surface area at 23.6±0.82 m 2/g. Its point of zero charge (pzc) was measured as 3.7±0.4. This birnessite is a relatively active species and could participate in various reactions with existing organic and inorganic matter. The dissolution kinetics of Mn oxide was evaluated in batch experiments using solutions of citric acid, oxalic acid, and ethylenediaminetetraacetic acid (EDTA). Initial dissolution rates were determined to be 0.126 mM/m 2/h for citric acid, 1.35 mM/m 2/h for oxalic acid, and 5.176 mM/m 2/h for EDTA. These rates compare with 0.0025 mM/m 2/h for nitric acid at pH=2. Organic acids dissolve Mn oxide quickly. Reaction rates increase with acid concentration, as tested with citric acid. The dissolution mechanism likely involves proton and ligand-promoted dissolution and reductive dissolution. Citric and oxalic acid can induce ligand-promoted dissolution, while EDTA can induce ligand-promoted and reductive dissolutions. At low pH, proton-promoted dissolution seems to occur with all the acids tested, but this process is not dominant. Reductive dissolution appears to be the most effective process in dissolving the solid, followed by ligand-promoted dissolution. These experiments indicate the significant

The effect of ethylenediaminetetraacetic acid on heat resistance and recovery of Clostridium sporogenes PA 3679 spores treated in HTST conditions.

PubMed

Silla Santos, M H; Torres Zarzo, J

1997-03-03

The effect of ethylenediaminetetraacetic acid (EDTA) on the heat resistance of Clostridium sporogenes PA 3679 spores was studied. EDTA was added to heating substrates and recovery media in order to establish which stage of the heat treatment registered the greatest EDTA activity. The heating substrates assayed were phosphate buffer (pH 7.0) and white asparagus purée, at natural pH (5.8) and acidified with citric acid and glucono-delta-lactone (GDL) to pH 5.5, 5.0 and 4.5. Recovery of survivors was carried out in MPA3679A medium in various conditions of acidification with citric and GDL (250 and 500 ppm), at pH 7.5 6.5 and 6.0. The results show greater activity of EDTA on spores when it was applied in recovery of heat injured spores, than during heating. The strongest influence of EDTA during heating was found in phosphate buffer (pH 7.0), with the effect being most evident at 121 and 126 degrees C, and in asparagus purée, at 121 degrees C and pH 5.8 rather than acidified. In recovery, the inhibiting activity of EDTA was more evident in spores subjected to more severe heat treatment, either by increasing the exposure time or by raising the temperature to 130 or 135 degrees C. The pH level of the recovery medium also affected the antimicrobial activity of EDTA, which had a greater inhibiting effect at pH 7.5 than at lower pH levels (6.5, 6.0).

In vitro digestion of citric acid esters of mono- and diglycerides (CITREM) and CITREM-containing infant formula/emulsions.

PubMed

Amara, Sawsan; Patin, Amaury; Giuffrida, Francesca; Wooster, Tim J; Thakkar, Sagar K; Bénarouche, Anaïs; Poncin, Isabelle; Robert, Sylvie; Point, Vanessa; Molinari, Sacha; Gaussier, Hélène; Diomande, Sadia; Destaillats, Frédéric; Cruz-Hernandez, Cristina; Carrière, Frédéric

2014-07-25

CITREM is an emulsifier used in the food industry and contains citric acid esters of mono- and diglycerides (GCFE). It is generally recognized as safe but no publication on its digestibility under gastrointestinal conditions and impact on fat digestion was available. It was shown here that fatty acids are released from CITREM by gastric lipase, pancreatic lipase, pancreatic-lipase-related protein 2 and carboxyl ester hydrolase. A two-step in vitro digestion model mimicking lipolysis in the stomach and upper small intestine of term and preterm infants was then used to evaluate the digestibility of CITREM alone, CITREM-containing infant formula and fat emulsions, and isolated GCFE fractions. Overall, it was shown that fat digestion is not significantly changed by the presence of CITREM, and fatty acids contained in CITREM compounds are released to a large extent by lipases. Nevertheless, undigestible water-soluble compounds containing glycerol and citric acid units were identified, indicating that the ester bond between citric acid and glycerol is not fully hydrolyzed throughout the proposed digestion.

Citric acid induced W18O49 electrochromic films with enhanced optical modulation

NASA Astrophysics Data System (ADS)

Xie, Junliang; Song, Bin; Zhao, Gaoling; Han, Gaorong

2018-06-01

Electrochromic materials exhibit promising applications in energy-saving fields for their ability to control heat from outdoors. Nanostructured W18O49 has drawn attention for its one-dimensional structure to transfer charge efficiently as a remarkable electrochromic material. W18O49 bi-layer films were fabricated through a facile one-step solvothermal process with citric acid as a chelating agent. The addition of citric acid improved the deposition on the substance, and a nanostructured film with a denser layer at the bottom and a tussock-like upper layer was obtained. The bi-layer film exhibited an enhanced optical modulation of 68.7%, a coloration efficiency of 82.1 cm2/C with stability over 400 cycles, and fast response times (1.4 s and 2.3 s for bleaching and coloring), with expectation to be applied in the electrochromic field.

Catalytic role of Cu(II) in the reduction of Cr(VI) by citric acid under an irradiation of simulated solar light.

PubMed

Li, Ying; Chen, Cheng; Zhang, Jing; Lan, Yeqing

2015-05-01

The catalytic role of Cu(II) in the reduction of Cr(VI) by citric acid with simulated solar light was investigated. The results demonstrated that Cu(II) could significantly accelerate Cr(VI) reduction and the reaction obeyed to pseudo zero-order kinetics with respect to Cr(VI). The removal of Cr(VI) was related to the initial concentrations of Cu(II), citric acid, and the types of organic acids. The optimal removal of Cr(VI) was achieved at pH 4, and the rates of Cu(II) photocatalytic reduction of Cr(VI) by organic acids were in the order: tartaric acid (two α-OH groups, two -COOH groups)>citric acid (one α-OH group, three -COOH groups)>malic acid (one α-OH group, two -COOH groups)>lactic acid (one α-OH group, one -COOH group)≫succinic acid (two -COOH groups), suggesting that the number of α-OH was the key factor for the reaction, followed by the number of -COOH. The formation of Cu(II)-citric acid complex could generate Cu(I) and radicals through a pathway of metal-ligand-electron transfer, promoting the reduction of Cr(VI). This study is helpful to fully understanding the conversion of Cr(VI) in the existence of both organic acids and Cu(II) with solar light in aquatic environments. Copyright © 2015 Elsevier Ltd. All rights reserved.

Controlling of dielectrical properties of hydroxyapatite by ethylenediamine tetraacetic acid (EDTA) for bone healing applications.

PubMed

Kaygili, Omer; Ates, Tankut; Keser, Serhat; Al-Ghamdi, Ahmed A; Yakuphanoglu, Fahrettin

2014-08-14

The hydroxyapatite (HAp) samples in the presence of various amounts of ethylenediamine tetraacetic acid (EDTA) were prepared by sol-gel method. The effects of EDTA on the crystallinity, phase structure, chemical, micro-structural and dielectric properties of HAp samples were investigated. With the addition of EDTA, the average crystallite size of the HAp samples is gradually decreased from 30 to 22 nm and the crystallinity is in the range of 65-71%. The values of the lattice parameters (a and c) and volume of the unit cell are decreased by stages with the addition of EDTA. The dielectric parameters such as relative permittivity, dielectric loss and relaxation time are affected by the adding of EDTA. The alternating current conductivity of the as-synthesized hydroxyapatites increases with the increasing frequency and obeys the universal power law behavior. The HAp samples exhibit a non-Debye relaxation mechanism. The obtained results that the dielectrical parameters of the HAp sample can be controlled by EDTA. Copyright © 2014 Elsevier B.V. All rights reserved.

Process optimization and leaching kinetics of zinc and manganese metals from zinc-carbon and alkaline spent batteries using citric acid reagent

NASA Astrophysics Data System (ADS)

Yuliusman; Amiliana, R. A.; Wulandari, P. T.; Huda, M.; Kusumadewi, F. A.

2018-03-01

Zn-Carbon and Alkaline spent batteries contains heavy metals, such as zinc and manganese, which can causes environmental problem if not handled properly. Usually the recovery of these metals were done by leaching method using strong acid, but the use of strong acids as leaching reagents can be harmful to the environment. This paper concerns the recovery of Zn and Mn metals from Zn-C and alkaline spent batteries with leaching method using citric acid as the environmental friendly leaching reagent. The leaching conditions using citric acid were optimized and the leaching kinetics of Zn and Mn in citric acid solution was investigated. The leaching of 89.62% Zn and 63.26% Mn was achieved with 1.5 M citric acid, 90°C temperature, and 90 minutes stirring time. Kinetics data for the dissolution of Zn showed the best fit to chemical control shrinking core model, while the diffusion controlled model was suitable for the dissolution of Mn kinetics data. The activation energy of 6.12 and 1.73 kcal/mol was acquired for the leaching of Zn and Mn in the temperature range 60°C-90°C.

Mast cell mediators in citric acid-induced airway constriction of guinea pigs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, C.-H.; Lai, Y.-L.

2005-08-15

We demonstrated previously that mast cells play an important role in citric acid (CA)-induced airway constriction. In this study, we further investigated the underlying mediator(s) for this type of airway constriction. At first, to examine effects caused by blocking agents, 67 young Hartley guinea pigs were divided into 7 groups: saline + CA; methysergide (serotonin receptor antagonist) + CA; MK-886 (leukotriene synthesis inhibitor) + CA; mepyramine (histamine H{sub 1} receptor antagonist) + CA; indomethacin (cyclooxygenase inhibitor) + CA; cromolyn sodium (mast cell stabilizer) + CA; and compound 48/80 (mast cell degranulating agent) + CA. Then, we tested whether leukotriene C{submore » 4} (LTC{sub 4}) or histamine enhances CA-induced airway constriction in compound 48/80-pretreated guinea pigs. We measured dynamic respiratory compliance (Crs) and forced expiratory volume in 0.1 s (FEV{sub 0.1}) during either baseline or recovery period. In addition, we detected histamine level, an index of pulmonary mast cell degranulation, in bronchoalveolar lavage (BAL) samples. Citric acid aerosol inhalation caused decreases in Crs and FEV{sub 0.1}, indicating airway constriction in the control group. This airway constriction was significantly attenuated by MK-886, mepyramine, cromolyn sodium, and compound 48/80, but not by either methysergide or indomethacin. Both LTC{sub 4} and histamine infusion significantly increased the magnitude of CA-induced airway constriction in compound 48/80-pretreated guinea pigs. Citric acid inhalation caused significant increase in histamine level in the BAL sample, which was significantly suppressed by compound 48/80. These results suggest that leukotrienes and histamine originating from mast cells play an important role in CA inhalation-induced noncholinergic airway constriction.« less

Citric acid production from hydrolysate of pretreated straw cellulose by Yarrowia lipolytica SWJ-1b using batch and fed-batch cultivation.

PubMed

Liu, Xiaoyan; Lv, Jinshun; Zhang, Tong; Deng, Yuanfang

2015-01-01

In this study, crude cellulase produced by Trichoderma reesei Rut-30 was used to hydrolyze pretreated straw. After the compositions of the hydrolysate of pretreated straw were optimized, the study showed that natural components of pretreated straw without addition of any other components such as (NH4)2SO4, KH2PO4, or Mg(2+) were suitable for citric acid production by Yarrowia lipolytica SWJ-1b, and the optimal ventilatory capacity was 10.0 L/min/L medium. Batch and fed-batch production of citric acid from the hydrolysate of pretreated straw by Yarrowia lipolytica SWJ-1b has been investigated. In the batch cultivation, 25.4 g/L and 26.7 g/L citric acid were yields from glucose and hydrolysate of straw cellulose, respectively, while the cultivation time was 120 hr. In the three-cycle fed-batch cultivation, citric acid (CA) production was increased to 42.4 g/L and the cultivation time was extended to 240 hr. However, iso-citric acid (ICA) yield in fed-batch cultivation (4.0 g/L) was similar to that during the batch cultivation (3.9 g/L), and only 1.6 g/L of reducing sugar was left in the medium at the end of fed-batch cultivation, suggesting that most of the added carbon was used in the cultivation.

Effects of citric acid and the siderophore desferrioxamine B (DFO-B) on the mobility of germanium and rare earth elements in soil and uptake in Phalaris arundinacea.

PubMed

Wiche, Oliver; Tischler, Dirk; Fauser, Carla; Lodemann, Jana; Heilmeier, Hermann

2017-08-03

Effects of citric acid and desferrioxamine B (DFO-B) on the availability of Ge and selected rare earth elements (REEs) (La, Nd, Gd, Er) to Phalaris arundinacea were investigated. A soil dissolution experiment was conducted to elucidate the effect of citric acid and DFO-B at different concentrations (1 and 10 mmol L -1 citric acid) on the release of Ge and REEs from soil. In a greenhouse, plants of P. arundinacea were cultivated on soil and on sand cultures to investigate the effects of citric acid and DFO-B on the uptake of Ge and REEs by the plants. Addition of 10 mmol L -1 citric acid significantly enhanced desorption of Ge and REEs from soil and uptake into soil-grown plants. Applying DFO-B enhanced the dissolution and the uptake of REEs, while no effect on Ge was observed. In sand cultures, the presence of citric acid and DFO-B significantly decreased the uptake of Ge and REEs, indicating a discrimination of the formed complexes during uptake. This study clearly indicates that citric acid and the microbial siderophore DFO-B may enhance phytoextraction of Ge and REEs due to the formation of soluble complexes that increase the migration of elements in the rhizosphere.

The effect of pH on hydrolysis, cross-linking and barrier properties of starch barriers containing citric acid.

PubMed

Olsson, Erik; Menzel, Carolin; Johansson, Caisa; Andersson, Roger; Koch, Kristine; Järnström, Lars

2013-11-06

Citric acid cross-linking of starch for e.g. food packaging applications has been intensely studied during the last decade as a method of producing water-insensitive renewable barrier coatings. We managed to improve a starch formulation containing citric acid as cross-linking agent for industrial paper coating applications by adjusting the pH of the starch solution. The described starch formulations exhibited both cross-linking of starch by citric acid as well as satisfactory barrier properties, e.g. fairly low OTR values at 50% RH that are comparable with EVOH. Furthermore, it has been shown that barrier properties of coated papers with different solution pH were correlated to molecular changes in starch showing both hydrolysis and cross-linking of starch molecules in the presence of citric acid. Hydrolysis was shown to be almost completely hindered at solution pH≥4 at curing temperatures≤105 °C and at pH≥5 at curing temperatures≤150 °C, whereas cross-linking still occurred to some extent at pH≤6.5 and drying temperatures as low as 70 °C. Coated papers showed a minimum in water vapor transmission rate at pH 4 of the starch coating solution, corresponding to the point where hydrolysis was effectively hindered but where a significant degree of cross-linking still occurred. Copyright © 2013 Elsevier Ltd. All rights reserved.

Geobiochemistry of metabolism: Standard state thermodynamic properties of the citric acid cycle

NASA Astrophysics Data System (ADS)

Canovas, Peter A.; Shock, Everett L.

2016-12-01

Integrating microbial metabolism into geochemical modeling allows assessments of energy and mass transfer between the geosphere and the microbial biosphere. Energy and power supplies and demands can be assessed from analytical geochemical data given thermodynamic data for compounds involved in catabolism and anabolism. Results are reported here from a critique of the available standard state thermodynamic data for organic acids and acid anions involved in the citric acid cycle (also known as the tricarboxylic acid cycle or the Krebs cycle). The development of methods for estimating standard state data unavailable from experiments is described, together with methods to predict corresponding values at elevated temperatures and pressures using the revised Helgeson-Kirkham-Flowers (HKF) equation of state for aqueous species. Internal consistency is maintained with standard state thermodynamic data for organic and inorganic aqueous species commonly used in geochemical modeling efforts. Standard state data and revised-HKF parameters are used to predict equilibrium dissociation constants for the organic acids in the citric acid cycle, and to assess standard Gibbs energies of reactions for each step in the cycle at elevated temperatures and pressures. The results presented here can be used with analytical data from natural and experimental systems to assess the energy and power demands of microorganisms throughout the habitable ranges of pressure and temperature, and to assess the consequences of abiotic organic compound alteration processes at conditions of subsurface aquifers, sedimentary basins, hydrothermal systems, meteorite parent bodies, and ocean worlds throughout the solar system.

Analysis of Citric Acid in Beverages: Use of an Indicator Displacement Assay

ERIC Educational Resources Information Center

Umali, Alona P.; Anslyn, Eric V.; Wright, Aaron T.; Blieden, Clifford R.; Smith, Carolyne K.; Tian, Tian; Truong, Jennifer A.; Crumm, Caitlin E.; Garcia, Jorge E.; Lee, Soal; Mosier, Meredith; Nguyen, Chester P.

2010-01-01

The use of an indicator displacement assay permits the visualization of binding events between host and guest molecules. An undergraduate laboratory experiment is described to demonstrate the technique in the determination of citric acid content in commercially available beverages such as soda pop and fruit juices. Through the technique, students…

Ultrasonic activation and chemical modification of photosensitizers enhances the effects of photodynamic therapy against Enterococcus faecalis root-canal isolates.

PubMed

Tennert, C; Drews, A M; Walther, V; Altenburger, M J; Karygianni, L; Wrbas, K T; Hellwig, E; Al-Ahmad, A

2015-06-01

The aim of this study was to evaluate the effect of photodynamic therapy (PDT) on Enterococcus faecalis biofilms in artificially infected root canals using modified photosensitizers and passive ultrasonic activation. Two hundred and seventy extracted human teeth with one root canal were instrumented utilizing ProTaper files, autoclaved, infected with E. faecalis T9 for 72 h and divided into different groups: irrigation with 3% sodium hypochlorite (NaOCl), 20% ethylenediaminetetraacetic acid (EDTA), or 20% citric acid, PDT without irrigation, PDT accompanied by irrigation with NaOCl, EDTA, or citric acid, PDT using an EDTA-based photosensitizer or a citric-acid-based photosensitizer and PDT with ultrasonic activation of the photosensitizer. A 15 mg/ml toluidine blue served as the photosensitizer, activated by a 100 mW LED light source. Sterile paper points were used for sampling the root canals and dentin chips were collected to assess the remaining contamination after treatment. Samples were cultured on blood agar plates and colony forming units were quantified. PDT alone achieved a reduction in E. faecalis counts by 92.7%, NaOCl irrigation alone and combined with PDT by 99.9%. The antibacterial effects increased by the combination of irrigation using EDTA or citric acid and PDT compared to irrigation alone. More than 99% of E. faecalis were killed using PDT with the modified photosensitizers and ultrasonic activation. NaOCl based disinfection achieved the highest antimicrobial effect. Using PDT with an EDTA-based or citric-acid-based phozosensitizer or activating the photosensitizer with ultrasound resulted in a significantly higher reduction in E. faecalis counts compared to conventional PDT. Copyright © 2015 Elsevier B.V. All rights reserved.

Comparison of acidic and neutral PH root conditioners prior to a coronally positioned flap to treat gingival recession

PubMed Central

Ahmadi, Roya Shariatmadar; Awwadi, Mohammd Reza; Moatazed, Shilan; Rezaei, Fatemeh; Hajisadeghi, Samira

2014-01-01

Background: Localized gingival recession can be treated successfully via coronally positioned flap (CPF) and additional use of root surface demineralization agents. The purpose of this study was to evaluate the effects of additional use of ethylene diamine tetraacetic acid (EDTA) and citric acid as a root conditioner in association with CPF to cover localized buccal gingival recessions. Materials and Methods: Twenty-seven patients with 66 Miller class I buccal gingival recession ≥ 2 mm on single-rooted teeth were studied. Patients were randomly assigned: CPF with EDTA gel (test 1) and CPF with saturated citric acid (test 2) or CPF alone (control). Clinical parameters were measured at baseline and 1, 2, 3 and 6 months after surgery; assessment included recession depth (RD), clinical attachment level (CAL), probing depth (PD) and height of keratinized gingiva (HKG). SPSS version-20 was used to perform all statistical analyses. Data was reported as Mean ± SD. Age, RD, CAL, PD, and HKG before treatment and after 6 months among study groups were compared by one-way ANOVA followed by the Tukey test. The level of significance was considered to be less than 0.05. Results: At 6 months, all treatment modalities showed significant root coverage and gain in CAL. RD was reduced from 2.86 ± 0.76 mm to 0.55±0.53 mm in the EDTA group and from 2.37±0.57 mm to 1.03±0.43 mm in the acid group and from 2.37±0.54 mm to 0.85±0.49 mm in the control group. The average percentage of root coverage for the EDTA, acid, and control groups were 80.73%, 52.16%, and 64.50%, respectively. At 6 months, there was a significant difference (P < 0.05) in all parameters for the EDTA group (except HKG that did not vary among the groups). Conclusion: Root preparation with EDTA was an effective procedure to cover localized gingival recessions and significantly improved the amount of root coverage obtained. PMID:25097639

Postrigor citric acid enhancement can alter cooked color but not fresh color of dark-cutting beef.

PubMed

Stackhouse, R J; Apple, J K; Yancey, J W S; Keys, C A; Johnson, T M; Mehall, L N

2016-04-01

In 2 experiments, dark-cutting (DC) beef strip loins were used to test the effects of citric acid-enhancement pH on visual and instrumental color of fresh and cooked steaks. In Exp. 1 and 2, each DC (mean pH = 6.57 and 6.65, respectively) and normal-pH, low USDA Choice (CH; mean pH = 5.48 and 5.51, respectively) strip loin was cut into 2 equal-length sections, and DC sections were injected to 111% of raw section weight with pH 3.5 to 5.0 (Exp. 1) or pH 2.0 to 3.5 (Exp. 2) solutions made by mixing citric acid in either 0.05% orthophosphate (PO) solution or tap water (HO) base solutions (Exp. 1) and 0.5% PO or 0.5% tripolyphosphate solution base solutions (Exp. 2). After enhancement, sections were cut into steaks, which were assigned to either 5 d of simulated retail display or cooked to 71°C for cooked color measurement. Postenhancement pH of DC steaks enhanced with pH 3.5 to 5.0 solutions did not ( ≥ 0.180) differ from that of nonenhanced DC steaks (Exp. 1) but linearly decreased ( < 0.001) as solution pH decreased from 3.5 to 2.0 (Exp. 2). Even though fresh color scores were increased ( < 0.001) by citric acid enhancement over untreated DC steaks during the first 3 d of display, fresh steak color never ( < 0.001) approached that of nonenhanced CH steaks. When compared with nonenhanced DC steaks, enhancement with pH 3.5 to 5.0 solutions received lower cooked color scores, whereas enhancing DC sections with pH 2.5 solutions produced cooked color and degree-of-doneness scores similar ( ≥ 0.113) to those of nonenhanced CH steaks (Exp. 2). Results indicated that the pH of citric acid enhancement solutions, regardless of base solution, were insufficient to improve the fresh color of DC beef; however, enhancement with pH 2.5 citric acid solutions effectively eliminated the persistent red cooked color typically associated with DC beef comparable with that of normal-pH beef.

Improving the degradation behavior and in vitro biological property of nano-hydroxyapatite surface- grafted with the assist of citric acid.

PubMed

Jiang, Liuyun; Jiang, Lixin; Xiong, Chengdong; Su, Shengpei

2016-10-01

To obtain ideal nano-hydroxyapatite(n-HA) filler for poly(lactide-co-glycolide) (PLGA), a new surface-grafting with the assist of citric acid for nano-hydroxyapatite (n-HA) was designed, and the effect of n-HA surface-grafted with or without citric acid on in vitro degradation behavior and cells viability was studied by the experiments of soaking in simulated body fluid (SBF) and incubating with human osteoblast-like cells (MG-63). The change of pH value, tensile strength reduction, the surface deposits, cells attachment and proliferation of samples during the soaking and incubation were investigated by means of pH meter, electromechanical universal tester, scanning electron microscope (SEM) coupled with energy-dispersive spectro-scopy (EDS), fluorescence microscope and MTT method. The results showed that the introduction of citric acid not only delayed the strength reduction during the degradation by inhibiting the detachment of n-HA from PLGA, but also endowed it better cell attachment and proliferation, suggesting that the n-HA surface-grafted with the assist of citric acid was an important bioactive ceramic fillers for PLGA used as bone materials. Copyright © 2016 Elsevier B.V. All rights reserved.

Influence of multi-step washing using Na2EDTA, oxalic acid and phosphoric acid on metal fractionation and spectroscopy characteristics from contaminated soil.

PubMed

Wei, Meng; Chen, Jiajun

2016-11-01

A multi-step soil washing test using a typical chelating agent (Na 2 EDTA), organic acid (oxalic acid), and inorganic weak acid (phosphoric acid) was conducted to remediate soil contaminated with heavy metals near an arsenic mining area. The aim of the test was to improve the heavy metal removal efficiency and investigate its influence on metal fractionation and the spectroscopy characteristics of contaminated soil. The results indicated that the orders of the multi-step washing were critical for the removal efficiencies of the metal fractions, bioavailability, and potential mobility due to the different dissolution levels of mineral fractions and the inter-transformation of metal fractions by XRD and FT-IR spectral analyses. The optimal soil washing options were identified as the Na 2 EDTA-phosphoric-oxalic acid (EPO) and phosphoric-oxalic acid-Na 2 EDTA (POE) sequences because of their high removal efficiencies (approximately 45 % for arsenic and 88 % for cadmium) and the minimal harmful effects that were determined by the mobility and bioavailability of the remaining heavy metals based on the metal stability (I R ) and modified redistribution index ([Formula: see text]).

An autopsy case of death due to metabolic acidosis after citric acid ingestion.

PubMed

Ikeda, Tomoya; Usui, Akihito; Matsumura, Takashi; Aramaki, Tomomi; Hosoya, Tadashi; Igari, Yui; Ohuchi, Tsukasa; Hayashizaki, Yoshie; Usui, Kiyotaka; Funayama, Masato

2015-11-01

A man in his 40s was found unconscious on a sofa in a communal residence for people with various disabilities. He appeared to have drunk 800 ml of undiluted citric acid from a commercial plastic bottle. The instructions on the label of the beverage specified that the beverage be diluted 20- to 30-fold before consumption. The patient was admitted to an emergency hospital with severe metabolic acidosis (pH, 6.70; HCO3(-), 3.6 mEq/L) and a low ionized calcium level (0.73 mmol/L). Although ionized calcium and catecholamines were continuously administered intravenously to correct the acidosis, the state of acidemia and low blood pressure did not improve, and he died 20 h later. Citric acid concentrations in the patient's serum drawn shortly after treatment in the hospital and from the heart at autopsy were 80.6 mg/ml and 39.8 mg/dl, respectively (normal range: 1.3-2.6 mg/dl). Autopsy revealed black discoloration of the mucosal surface of the esophagus. Microscopically, degenerated epithelium and neutrophilic infiltration in the muscle layer were observed. In daily life, drinking a large amount of concentrated citric acid beverage is rare as a cause of lethal poisoning. However, persons with mental disorders such as dementia may mistakenly drink detergent or concentrated fluids, as in our case. Family members or facility staff in the home or nursing facility must bear in mind that they should not leave such bottles in places where they are easily accessible to mentally handicapped persons. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Quality enhancement in the Japanese sea bass (Lateolabrax japonicas) fillets stored at 4°C by chitosan coating incorporated with citric acid or licorice extract.

PubMed

Qiu, Xujian; Chen, Shengjun; Liu, Guangming; Yang, Qiuming

2014-11-01

The preserving effects of chitosan, chitosan and citric acid, chitosan and licorice extract on fresh Japanese sea bass fillets stored at 4 °C for 12 days were studied. Results showed that citric acid or licorice extract can enhance the preserving function of chitosan significantly by retarding lipid oxidation and inhibiting microbial growth as reflected in thiobarbituric acid reactive substances and total plate count, respectively. Both total volatile basic nitrogen values and sensory scores indicated chitosan and citric acid or licorice extract can significantly reduce the quality loss and extend the shelf life of Japanese sea bass fish fillets during refrigerated storage. Citric acid or licorice extract with chitosan could thus be applied in the seafood industry to enhance quality of fish fillets as natural preservatives. Copyright © 2014 Elsevier Ltd. All rights reserved.

Improving iron absorption from a Peruvian school breakfast meal by adding ascorbic acid or Na2EDTA.

PubMed

Davidsson, L; Walczyk, T; Zavaleta, N; Hurrell, R

2001-02-01

Iron-fortified school breakfasts have been introduced in Peru to combat childhood iron deficiency. We evaluated whether iron absorption from a school breakfast meal was improved by increasing the ascorbic acid content or by adding an alternative enhancer of iron absorption, Na2EDTA. In a crossover design, iron absorption from test meals was evaluated by erythrocyte incorporation of 58Fe and 57Fe. The test meals (wheat bread and a drink containing cereal, milk, and soy) contained 14 mg added Fe (as ferrous sulfate) including 2.0-2.6 mg 58Fe or 4.0-7.0 mg 57Fe. Geometric mean iron absorption increased significantly from 5.1% to 8.2% after the molar ratio of ascorbic acid to fortification iron was increased from 0.6:1 to 1.6:1 (P < 0.01; n = 9). Geometric mean iron absorption increased significantly from 2.9% to 3.8%, from 2.2% to 3.5%, and from 2.4% to 3.7% after addition of Na2EDTA at molar ratios relative to fortification iron of 0.3:1, 0.7:1, and 1:1, respectively, compared with test meals containing no added enhancers (P < 0.01; n = 10 for all). Iron absorption after addition of ascorbic acid (molar ratio 0.6:1) was not significantly different from that after addition of Na2EDTA (molar ratio 0.7:1). Ascorbic acid and Na2EDTA did not differ significantly in their enhancing effects on iron absorption at molar ratios of 0.6:1 to 0.7:1 relative to fortification iron. Additional ascorbic acid (molar ratio 1.6:1) increased iron absorption significantly. Increasing the molar ratio of Na2EDTA to fortification iron from 0.3:1 to 1:1 had no effect on iron absorption.

Improving clarity and stability of skim milk powder dispersions by dissociation of casein micelles at pH 11.0 and acidification with citric acid.

PubMed

Pan, Kang; Zhong, Qixin

2013-09-25

Casein micelles in milk cause turbidity and have poor stability at acidic conditions. In this study, skim milk powder dispersions were alkalized to pH 10.0 or 11.0, corresponding to reduced particle mass. In the following acidification with hydrochloric or citric acid, the re-formation of casein particles was observed. The combination of treatment at pH 11.0 and acidification with citric acid resulted in dispersions with the lowest turbidity and smallest particles, which enabled translucent dispersions at pH 5.5-7.0, corresponding to discrete nanoparticles. The concentration of ionic calcium was lower when acidified with citric acid than hydrochloric acid, corresponding to smaller particles with less negative zeta potential. The pH 11.0 treatment followed by acidification with citric acid also resulted in smaller particles than the simple chelating effects (directly implementing sodium citrate). The produced casein nanoparticles with reduced dimensions can be used for beverage and other novel applications.

Sudden substrate dilution induces a higher rate of citric acid production by Aspergillus niger.

PubMed Central

Legisa, M; Gradisnik-Grapulin, M

1995-01-01

On the basis of the present knowledge of Aspergillus niger metabolism during citric acid fermentation, an idea on how to improve the process was formed. Initially, a higher sucrose concentration was used for the germination of spores, which caused a higher intracellular level of the osmoregulator, glycerol, to be present. When citric acid started to be excreted into the medium, the substrate was suddenly diluted. Optimization of this procedure resulted in a nearly tripled volumetric rate (grams per liter per hour) of acid production, while the overall fermentation time was halved compared with the usual batch process. Yet, a characteristic delay was observed at the start of the acid excretion after the dilution. Hypo-osmotic shock caused a prominent elevation of intracellular cyclic AMP levels. Simultaneously, the specific activity of 6-phosphofructo-1-kinase increased significantly, probably due to phosphorylation of the protein molecule by cyclic AMP-dependent protein kinase. Specific 6-phosphofructo-1-kinase activity was much higher in the treated than in the normally growing mycelium. The metabolic flow through glycolysis was expected to be higher, which should contribute to a higher volumetric rate of acid production. PMID:7618885

Sudden substrate dilution induces a higher rate of citric acid production by Aspergillus niger.

PubMed

Legisa, M; Gradisnik-Grapulin, M

1995-07-01

On the basis of the present knowledge of Aspergillus niger metabolism during citric acid fermentation, an idea on how to improve the process was formed. Initially, a higher sucrose concentration was used for the germination of spores, which caused a higher intracellular level of the osmoregulator, glycerol, to be present. When citric acid started to be excreted into the medium, the substrate was suddenly diluted. Optimization of this procedure resulted in a nearly tripled volumetric rate (grams per liter per hour) of acid production, while the overall fermentation time was halved compared with the usual batch process. Yet, a characteristic delay was observed at the start of the acid excretion after the dilution. Hypo-osmotic shock caused a prominent elevation of intracellular cyclic AMP levels. Simultaneously, the specific activity of 6-phosphofructo-1-kinase increased significantly, probably due to phosphorylation of the protein molecule by cyclic AMP-dependent protein kinase. Specific 6-phosphofructo-1-kinase activity was much higher in the treated than in the normally growing mycelium. The metabolic flow through glycolysis was expected to be higher, which should contribute to a higher volumetric rate of acid production.

Discovery of a Chemical Modification by Citric Acid in a Recombinant Monoclonal Antibody

PubMed Central

2015-01-01

Recombinant therapeutic monoclonal antibodies exhibit a high degree of heterogeneity that can arise from various post-translational modifications. The formulation for a protein product is to maintain a specific pH and to minimize further modifications. Generally Recognized as Safe (GRAS), citric acid is commonly used for formulation to maintain a pH at a range between 3 and 6 and is generally considered chemically inert. However, as we reported herein, citric acid covalently modified a recombinant monoclonal antibody (IgG1) in a phosphate/citrate-buffered formulation at pH 5.2 and led to the formation of so-called “acidic species” that showed mass increases of 174 and 156 Da, respectively. Peptide mapping revealed that the modification occurred at the N-terminus of the light chain. Three additional antibodies also showed the same modification but displayed different susceptibilities of the N-termini of the light chain, heavy chain, or both. Thus, ostensibly unreactive excipients under certain conditions may increase heterogeneity and acidic species in formulated recombinant monoclonal antibodies. By analogy, other molecules (e.g., succinic acid) with two or more carboxylic acid groups and capable of forming an anhydride may exhibit similar reactivities. Altogether, our findings again reminded us that it is prudent to consider formulations as a potential source for chemical modifications and product heterogeneity. PMID:25136741

Citric acid treatment of chronic nonhealing ulcerated tophaceous gout with bursitis.

PubMed

Nagoba, Basavaraj S; Punpale, Ajay; Poddar, Ashok; Suryawanshi, Namdev M; Swami, Ganesh A; Selkar, Sohan P

2013-12-01

The ulceration associated with gout tophi is very difficult to treat because of impaired and halted local inflammatory response resulting from the gout treatment regimen. We report chronic nonhealing tophaceous gout with bursitis in an 80-year-old male, not responding to conventional treatment modality for months together. This nonhealing ulcer was treated successfully with local application of 3% citric acid ointment for 22 days.

Mitochondria dysfunctions under Fe and S deficiency: is citric acid involved in the regulation of adaptive responses?

PubMed

Vigani, Gianpiero; Pii, Youry; Celletti, Silvia; Maver, Mauro; Mimmo, Tanja; Cesco, Stefano; Astolfi, Stefania

2018-05-01

Within the last years, extensive information has been accumulated on the reciprocal influence between S and Fe nutrition at both physiological and molecular level in several plant species, but the mechanisms regulating S and Fe sensing and signaling are not fully understood. Fe and S interact for the building of Fe-S clusters, and mitochondria is one of the cellular compartments where Fe-S cluster assembly takes place. Therefore, it would be expected that mitochondria might play a central role in the regulation of Fe and S interaction. The Fe deficiency-induced alteration in the synthesis of mitochondria-derived carboxylic acids, such as citric acid, and the evidence that such molecules have already been identified as important players of metabolite signaling in several organisms, further support this hypothesis. Tomato plants were grown under single or combined Fe and S deficiency with the aim of verifying whether mitochondria activities played a role in Fe/S interaction. Both Fe and S deficiencies determined similar alteration of respiratory chain activity: a general decrease of Fe-S containing complexes as well as an increase of alternative NAD(P)H activities was observed in both Fe and S deficient-plants. However, the content of Krebs cycle-related organic acids in roots was substantially different in response to treatments, being the accumulation of citric acid always increased, while the others (i.e. succinic, malic, fumaric acids) always decreased. Interestingly, citric acid levels significantly correlated with the expression of some Fe and S deficiency induced genes. Our results contribute to existing knowledge on the complexity of the S/Fe interaction, suggesting a model in which endogenous alteration of citric acid content in plant tissues might act as signal molecule for the regulation of some nuclear-encoded and nutrient-responsive genes and also provide a basis for further study of the mechanism underlying S and Fe sensing and signalling. Copyright �

[Comparative studies on the quantity of fructose and citric acid in the sperm from bulls at different seasons of the year].

PubMed

Doĭcheva, M; Stoianov, T; Tunchev, T

1978-01-01

The contents of fructose and citric acid in the semen of seven bulls of different ages were examined over a one-year period. The bulls were used as sires in the Artificial Insemination Station. The semen production was within the normal range. In the course of the investigations the temperature and moisture regimes of the air in the barns was optimal for the semen production of the bulls. No statistically significant changes in the amount of fructose and citric acid were established at different average diurnal temperatures and the relative moisture content in the different annual seasons. A marked positive correlation (r = 0.070 +/- 0.04) was observed between the changes in the contents of fructose and citric acid throughout the year. These changes were in an inverse correlation with the number of spermatozoa per mL of semen (r = 0.26 +/- 0.08) and in a moderate one for the citric acid (r = 0.49 +/- 0.06). In the bulls of the Red Dannish cattle there was a statistically significant decrease in the number of spermatozoa and a statistically significant increase in the number of immobile spermatozoa in the winter season.

EDTA and HCl leaching of calcareous and acidic soils polluted with potentially toxic metals: remediation efficiency and soil impact.

PubMed

Udovic, Metka; Lestan, Domen

2012-07-01

The environmental risk of potentially toxic metals (PTMs) in soil can be diminished by their removal. Among the available remediation techniques, soil leaching with various solutions is one of the most effective but data about the impact on soil chemical and biological properties are still scarce. We studied the effect of two common leaching agents, hydrochloric acid (HCl) and a chelating agent (EDTA) on Pb, Zn, Cd removal and accessibility and on physico-chemical and biological properties in one calcareous, pH neutral soil and one non-calcareous acidic soil. EDTA was a more efficient leachant compared to HCl: up to 133-times lower chelant concentration was needed for the same percentage (35%) of Pb removal. EDTA and HCl concentrations with similar PTM removal efficiency decreased PTM accessibility in both soils but had different impacts on soil properties. As expected, HCl significantly dissolved carbonates from calcareous soil, while EDTA leaching increased the pH of the acidic soil. Enzyme activity assays showed that leaching with HCl had a distinctly negative impact on soil microbial and enzyme activity, while leaching with EDTA had less impact. Our results emphasize the importance of considering the ecological impact of remediation processes on soil in addition to the capacity for PTM removal. Copyright © 2012 Elsevier Ltd. All rights reserved.

Citric-acid preacidification enhanced electrokinetic remediation for removal of chromium from chromium-residue-contaminated soil.

PubMed

Meng, Fansheng; Xue, Hao; Wang, Yeyao; Zheng, Binghui; Wang, Juling

2018-02-01

Electrokinetic experiments were conducted on chromium-residue-contaminated soils collected from a chemical plant in China. Acidification-electrokinetic remediation technology was proposed in order to solve the problem of removing inefficient with ordinary electrokinetic. The results showed that electrokinetic remediation removal efficiency of chromium from chromium-contaminated soil was significantly enhanced with acidizing pretreatment. The total chromium [Cr(T)] and hexavalent chromium [Cr(VI)] removal rate of the group acidized by citric acid (0.9 mol/L) for 5 days was increased from 6.23% and 19.01% in the acid-free experiments to 26.97% and 77.66% in the acidification-treated experiments, respectively. In addition, part of chromium with the state of carbonate-combined will be converted into water-soluble state through acidification to improve the removal efficiency. Within the appropriate concentration range, the higher concentration of acid was, the more chromium was released. So the removal efficiency of chromium depended on the acid concentration. The citric acid is also a kind of complexing agent, which produced complexation with Cr that was released by the electrokinetic treatment and then enhanced the removal efficiency. The major speciation of chromium that was removed from soils by acidification-electrokinetics remediation was acid-soluble speciation, revivification speciation and oxidation speciation, which reduced biological availability of chromium.

Effect of whey protein isolate films incorporated with montmorillonite and citric acid on the preservation of fresh-cut apples.

PubMed

Azevedo, Viviane Machado; Dias, Marali Vilela; de Siqueira Elias, Heloisa Helena; Fukushima, Katia Lumi; Silva, Eric Keven; de Deus Souza Carneiro, João; de Fátima Ferreira Soares, Nilda; Borges, Soraia Vilela

2018-05-01

The objective of this paper was to evaluate the effect of bioactive whey protein isolate/montmorillonite films containing citric acid on the inhibition of enzymatic browning and physicochemical properties in minimally processed apples. Whey protein isolate films incorporated with montmorillonite (3 g/100 g) and citric acid (5 and 10 g/100 g) were applied to the apples slices. All samples were packaged in polypropylene trays (14.6 cm × 11.4 cm × 6.5 cm) and stored at 5 ± 2 °C and 85 ± 3% RH for eight days. Every two days, the apples samples were evaluated for color, acidity, pH, soluble solids, water activity and polyphenol oxidase and peroxidase enzyme activity. The enzymatic browning of the apples slices was reduced for all films during storage. However, the films containing citric acid maintained the color characteristics, reducing the loss of quality associated the maintenance of acidity, soluble solids, water activity, reduction of polyphenol oxidase and peroxidase activity, thus prolonging the shelf life of the apples. Copyright © 2018 Elsevier Ltd. All rights reserved.

Metabolic Interaction between Urea Cycle and Citric Acid Cycle Shunt: A Guided Approach

ERIC Educational Resources Information Center

Pesi, Rossana; Balestri, Francesco; Ipata, Piero L.

2018-01-01

This article is a guided pedagogical approach, devoted to postgraduate students specializing in biochemistry, aimed at presenting all single reactions and overall equations leading to the metabolic interaction between ureagenesis and citric acid cycle to be incorporated into a two-three lecture series about the interaction of urea cycle with other…

Effects of heat/citric acid reprocessing on high-flux polysulfone dialyzers.

PubMed

Cornelius, Rena M; McClung, W Glenn; Richardson, Robert M A; Estridge, Charles; Plaskos, Nicholas; Yip, Christopher M; Brash, John L

2002-01-01

The surface features, morphology, and tensile properties of fibers obtained from pristine, reprocessed, and reused Fresenius Polysulfone High-Flux (Hemoflow F80A) hemodialyzers have been studied. Scanning electron microscopy of the dialyzer fibers revealed a dense skin layer on the inner surface of the membrane and a relatively thick porous layer on the outer surface. Transmission electron microscopy and atomic force microscopy showed an alteration in membrane morphology due to reprocessing and reuse, or to a deposition of blood-borne material on the membrane that is not removed with reprocessing. Fluorescent microscopy images also showed that a fluorescent material not removed by heat/citric acid reprocessing builds up with continued use of the dialyzers. The tensile properties of the dialyzer fibers were not affected by the heat/citric acid reprocessing procedure. The protein layers formed on pristine and reused hemodialyzer membranes during clinical use were also studied using sodium dodecyl sulfate polyacrylamide gel electrophoresis and immunoblotting. A considerable amount of protein was found on the blood side of single and multiple use dialyzers. Proteins adsorbed on the dialysate side of the membrane were predominantly in the molecular weight region below 30 kDa. Little protein was detected on the membranes of reprocessed hemodialyzers.

Citrus CitNAC62 cooperates with CitWRKY1 to participate in citric acid degradation via up-regulation of CitAco3.

PubMed

Li, Shao-Jia; Yin, Xue-Ren; Wang, Wen-Li; Liu, Xiao-Fen; Zhang, Bo; Chen, Kun-Song

2017-06-15

Citric acid is the predominant organic acid of citrus fruit. Degradation of citric acid occurs during fruit development, influencing fruit acidity. Associations of CitAco3 transcripts and citric acid degradation have been reported for citrus fruit. Here, transient overexpression of CitAco3 significantly reduced the citric acid content of citrus leaves and fruits. Using dual luciferase assays, it was shown that CitNAC62 and CitWRKY1 could transactivate the promoter of CitAco3. Subcellular localization results showed that CitWRKY1 was located in the nucleus and CitNAC62 was not. Yeast two-hybrid analysis and bimolecular fluorescence complementation (BiFC) assays indicated that the two differently located transcription factors could interact with each other. Furthermore, BiFC showed that the protein-protein interaction occurred only in the nucleus, indicating the potential mobility of CitNAC62 in plant cells. A synergistic effect on citrate content was observed between CitNAC62 and CitWRKY1. Transient overexpression of CitNAC62 or CitWRKY1 led to significantly lower citrate content in citrus fruit. The combined expression of CitNAC62 and CitWRKY1 resulted in lower citrate content compared with the expression of CitNAC62 or CitWRKY1 alone. The transcript abundance of CitAco3 was consistent with the citrate content. Thus, we propose that a complex of CitWRKY1 and CitNAC62 contributes to citric acid degradation in citrus fruit, potentially via modulation of CitAco3. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

The effect of cellulose nanocrystal (CNC) from rattan biomass as filler and citric acid as co-plasticizer on tensile properties of sago starch biocomposite

NASA Astrophysics Data System (ADS)

Nasution, Halimatuddahliana; Harahap, Hamidah; Afandy, Yayang; Fath, M. Thoriq Al

2017-11-01

Biocomposite containing cellulose nanocrystals (CNC) from rattan biomass as fillers and citric acid as co-plasticizer. Rattan biomass is a fiber waste from processing industry of rattan which contains 37.6% cellulose. Isolation of alpha cellulose from rattan biomass was prepared by using three stages: delignification, alkalization, and bleaching. It was delignificated with 3.5% HNO3 and NaNO2, precipitated with 17.5% NaOH, bleaching process with 10% H2O2. The preparation of CNC includes acid hydrolysis using 45% H2SO4 and followed by mechanical processes of ultrasonication, centrifugation, and filtration with a dialysis membrane. Biocomposite was prepared using a solution casting method, which includes 1-4 wt % CNC as fillers, 10-40 wt% citric acid as co-plasticizer and 30 wt% glycerol as plasticizer. The results of TGA, SEM and XRD characteristic of CNC show that CNC has low residue mass, rod like and network like shape with crystallinity index 84.46%. Biocomposite characteristic consists of SEM, tensile strength and elongation at break. The resultshows that biocomposites by addition of CNC and citric acid have a smooth surface and homogeneous distribution of fillers. The tensile strength of biocomposites was increased by addition CNC and citric acid. The addition of CNC decreases the elongation at break but by addition of citric acid, the elongation at break was increased.

Use of theophylline in the investigation of pseudothrombocytopenia induced by edetic acid (EDTA-2K).

PubMed Central

Ohnuma, O; Shirata, Y; Miyazawa, K

1988-01-01

In automated cell counting of edetic acid (EDTA-2K) anticoagulated blood, thrombocytopenia is occasionally seen which bears no relation to any underlying disease. In this study a heparin and soluble theophylline mixture was used to measure accurately platelet numbers in patients with such pseudothrombocytopenia. In four normal volunteers, a theophylline concentration of more than 7 mg/ml produced no significant difference in platelet numbers between theophylline and heparin and EDTA-2K anticoagulated bloods. When blood treated with EDTA-2K was used in seven patients with pseudothrombocytopenia, falsely low platelet counts were observed in three patients immediately after sampling; in blood treated with theophylline, white cell and platelet counts remained unchanged for up to six hours after sampling. Microscopical examination of the EDTA-2K anticoagulated blood showed massive platelet clumping, but no aggregates were seen in theophylline anticoagulated blood. It is concluded that theophylline can be useful in the investigation of pseudothrombocytopenia when an automated cell counter is used. PMID:3139717

Comment on "Analysis of Citric Acid in Beverages: Use of an Indicator Displacement Assay"

ERIC Educational Resources Information Center

Konski, Krzysiek; Saw, Jessica; Torriero, Angel A. J.

2017-01-01

This letter comments on the paper "Analysis of Citric Acid in Beverages: Use of an Indicator Displacement Assay" ["J. Chem. Educ." 2010, 87 (8), 832-835 (EJ918557)]. Discrepancies in figures and host:indicator complex behavior are discussed and an alternative experimental protocol presented.

Mechanism of permeability-enhancing effect of EDTA and boric acid on the corneal penetration of 4-[1-hydroxy-1-methylethyl]-2-propyl-1-[4-[2-[tetrazole-5-yl]phenyl]phenyl] methylimidazole-5-carboxylic acid monohydrate (CS-088).

PubMed

Kikuchi, Takayuki; Suzuki, Masahiko; Kusai, Akira; Iseki, Ken; Sasaki, Hitoshi; Nakashima, Kenichiro

2005-08-11

This study was conducted to clarify the penetration properties of 4-[1-hydroxy-1-methylethyl]-2-propyl-1-[4-[2-[tetrazole-5-yl]phenyl]phenyl]methylimidazole-5-carboxylic acid monohydrate (CS-088), an ophthalmic agent, and the mechanism of the permeability-enhancing effect of EDTA and boric acid (EDTA/boric acid) on the corneal penetration of CS-088. In the absence of additives, corneal permeability decreased with increasing concentration of CS-088 as CS-088 monomers self-associate to form dimers. Presence of EDTA/boric acid caused no significant changes in the physicochemical properties of CS-088, the apparent partition coefficient or the mean particle size of CS-088. EDTA/boric acid induced only a slight change in the zeta potential of liposomes used as a model of the biological membrane. On the other hand, EDTA/boric acid significantly increased membrane fluidity of liposomes, whereas other buffering agents tested did not. This effect was synergistic and concentration-dependent for both EDTA and boric acid as was observed in in vitro corneal penetration of CS-088. In accordance with the result, the rate of CS-088 permeation into the liposomes significantly increased by the addition of EDTA/boric acid. Therefore, it was demonstrated that EDTA/boric acid promotes corneal penetration of CS-088 through the transcellular pathway by increasing membrane fluidity. Conversely, other buffering agents decreased corneal permeability of CS-088 by inducing further self-association of CS-088 aggregates.

Ultrasound-assisted extraction of pectins from grape pomace using citric acid: a response surface methodology approach.

PubMed

Minjares-Fuentes, R; Femenia, A; Garau, M C; Meza-Velázquez, J A; Simal, S; Rosselló, C

2014-06-15

An ultrasound-assisted procedure for the extraction of pectins from grape pomace with citric acid as the extracting agent was established. A Box-Behnken design (BBD) was employed to optimize the extraction temperature (X1: 35-75°C), extraction time (X2: 20-60 min) and pH (X3: 1.0-2.0) to obtain a high yield of pectins with high average molecular weight (MW) and degree of esterification (DE) from grape pomace. Analysis of variance showed that the contribution of a quadratic model was significant for the pectin extraction yield and for pectin MW whereas the DE of pectins was more influenced by a linear model. An optimization study using response surface methodology was performed and 3D response surfaces were plotted from the mathematical model. According to the RSM model, the highest pectin yield (∼32.3%) can be achieved when the UAE process is carried out at 75°C for 60 min using a citric acid solution of pH 2.0. These pectic polysaccharides, composed mainly by galacturonic acid units (<97% of total sugars), have an average MW of 163.9 kDa and a DE of 55.2%. Close agreement between experimental and predicted values was found. These results suggest that ultrasound-assisted extraction could be a good option for the extraction of functional pectins with citric acid from grape pomace at industrial level. Copyright © 2014 Elsevier Ltd. All rights reserved.

Impact of chelator-induced phytoextraction of cadmium on yield and ionic uptake of maize.

PubMed

Anwar, Sumera; Khan, Shahbaz; Ashraf, M Yasin; Noman, Ali; Zafar, Sara; Liu, Lijun; Ullah, Sana; Fahad, Shah

2017-06-03

Enhanced phytoextraction uses soil chelators to increase the bioavailability of heavy metals. This study tested the effectiveness of ethylenediaminetetraacetic acid (EDTA) and citric acid in enhancing cadmium (Cd) phytoextraction and their effects on the growth, yield, and ionic uptake of maize (Zea mays). Maize seeds of two cultivars were sown in pots treated with 15 (Cd 15 ) or 30 mg Cd kg -1 soil (Cd 30 ). EDTA and citric acid at 0.5 g kg -1 each were applied 2 weeks after germination. Results demonstrated that the growth, yield per plant, and total grain weight were reduced by exposure to Cd. EDTA increased the uptake of Cd in shoots, roots, and grains of both maize varieties. Citric acid did not enhance the uptake of Cd, rather it ameliorated the toxicity of Cd, as shown by increased shoot and root length and biomass. Cadmium toxicity reduced the number of grains, rather than the grain size. The maize cultivar Sahiwal-2002 extracted 1.6% and 3.6% of Cd from soil in both Cd+ EDTA treatments. Hence, our study implies that maize can be used to successfully phytoremediate Cd from soil using EDTA, without reducing plant biomass or yield.

The Citrus transcription factor, CitERF13, regulates citric acid accumulation via a protein-protein interaction with the vacuolar proton pump, CitVHA-c4

PubMed Central

Li, Shao-jia; Yin, Xue-ren; Xie, Xiu-lan; Allan, Andrew C.; Ge, Hang; Shen, Shu-ling; Chen, Kun-song

2016-01-01

Organic acids are essential to fruit flavor. The vacuolar H+ transporting adenosine triphosphatase (V-ATPase) plays an important role in organic acid transport and accumulation. However, less is known of V-ATPase interacting proteins and their relationship with organic acid accumulation. The relationship between V-ATPase and citric acid was investigated, using the citrus tangerine varieties ‘Ordinary Ponkan (OPK)’ and an early maturing mutant ‘Zaoshu Ponkan (ZPK)’. Five V-ATPase genes (CitVHA) were predicted as important to citric acid accumulation. Among the genes, CitVHA-c4 was observed, using a yeast two-hybrid screen, to interact at the protein level with an ethylene response factor, CitERF13. This was verified using bimolecular fluorescence complementation assays. A similar interaction was also observed between Arabidopsis AtERF017 (a CitERF13 homolog) and AtVHA-c4 (a CitVHA-c4 homolog). A synergistic effect on citric acid levels was observed between V-ATPase proteins and interacting ERFs when analyzed using transient over-expression in tobacco and Arabidopsis mutants. Furthermore, the transcript abundance of CitERF13 was concomitant with CitVHA-c4. CitERF13 or AtERF017 over-expression leads to significant citric acid accumulation. This accumulation was abolished in an AtVHA-c4 mutant background. ERF-VHA interactions appear to be involved in citric acid accumulation, which was observed in both citrus and Arabidopsis. PMID:26837571

The Citrus transcription factor, CitERF13, regulates citric acid accumulation via a protein-protein interaction with the vacuolar proton pump, CitVHA-c4.

PubMed

Li, Shao-jia; Yin, Xue-ren; Xie, Xiu-lan; Allan, Andrew C; Ge, Hang; Shen, Shu-ling; Chen, Kun-song

2016-02-03

Organic acids are essential to fruit flavor. The vacuolar H(+) transporting adenosine triphosphatase (V-ATPase) plays an important role in organic acid transport and accumulation. However, less is known of V-ATPase interacting proteins and their relationship with organic acid accumulation. The relationship between V-ATPase and citric acid was investigated, using the citrus tangerine varieties 'Ordinary Ponkan (OPK)' and an early maturing mutant 'Zaoshu Ponkan (ZPK)'. Five V-ATPase genes (CitVHA) were predicted as important to citric acid accumulation. Among the genes, CitVHA-c4 was observed, using a yeast two-hybrid screen, to interact at the protein level with an ethylene response factor, CitERF13. This was verified using bimolecular fluorescence complementation assays. A similar interaction was also observed between Arabidopsis AtERF017 (a CitERF13 homolog) and AtVHA-c4 (a CitVHA-c4 homolog). A synergistic effect on citric acid levels was observed between V-ATPase proteins and interacting ERFs when analyzed using transient over-expression in tobacco and Arabidopsis mutants. Furthermore, the transcript abundance of CitERF13 was concomitant with CitVHA-c4. CitERF13 or AtERF017 over-expression leads to significant citric acid accumulation. This accumulation was abolished in an AtVHA-c4 mutant background. ERF-VHA interactions appear to be involved in citric acid accumulation, which was observed in both citrus and Arabidopsis.

Citric acid modified kenaf core fibres for removal of methylene blue from aqueous solution.

PubMed

Sajab, Mohd Shaiful; Chia, Chin Hua; Zakaria, Sarani; Jani, Saad Mohd; Ayob, Mohd Khan; Chee, Kah Leong; Khiew, Poi Sim; Chiu, Wee Siong

2011-08-01

Chemically modified kenaf core fibres were prepared via esterification in the presence of citric acid (CA). The adsorption kinetics and isotherm studies were carried out under different conditions to examine the adsorption efficiency of CA-treated kenaf core fibres towards methylene blue (MB). The adsorption capacity of the kenaf core fibres increased significantly after the citric acid treatment. The values of the correlation coefficients indicated that the Langmuir isotherm fitted the experimental data better than the Freundlich isotherm. The maximum adsorption capacity of the CA-treated kenaf core fibres was found to be 131.6mg/g at 60°C. Kinetic models, pseudo-first-order, pseudo-second-order and intraparticle diffusion, were employed to describe the adsorption mechanism. The kinetic data were found to fit pseudo-second-order model equation as compared to pseudo-first-order model. The adsorption of MB onto the CA-treated kenaf core fibres was spontaneous and endothermic. Copyright © 2011 Elsevier Ltd. All rights reserved.

Enhanced biocompatibility and antibacterial property of polyurethane materials modified with citric acid and chitosan.

PubMed

Liu, Tian-Ming; Wu, Xing-Ze; Qiu, Yun-Ren

2016-08-01

Citric acid (CA) and chitosan (CS) were covalently immobilized on polyurethane (PU) materials to improve the biocompatibility and antibacterial property. The polyurethane pre-polymer with isocyanate group was synthesized by one pot method, and then grafted with citric acid, followed by blending with polyethersulfone (PES) to prepare the blend membrane by phase-inversion method so that chitosan can be grafted from the membrane via esterification and acylation reactions eventually. The native and modified membranes were characterized by attenuated total reflectance-Fourier transform infrared spectroscope, X-ray photoelectron spectroscopy, scanning electron microscopy, water contact angle measurement, and tensile strength test. Protein adsorption, platelet adhesion, hemolysis assay, activated partial thromboplastin time, prothrombin time, thrombin time, and adsorption of Ca(2+) were executed to evaluate the blood compatibility of the membranes decorated by CA and CS. Particularly, the antibacterial activities on the modified membranes were evaluated based on a vitro antibacterial test. It could be concluded that the modified membrane had good anticoagulant property and antibacterial property.

Effect of EDTA and Fe-EDTA complex concentration on TCF Kraft mill effluent degradability. Batch and continuous treatments.

PubMed

Diez, M C; Pouleurs, D; Navia, R; Vidal, G

2005-09-01

The effect of ethylenediaminetetracetic acid (EDTA) and Fe-EDTA complex on synthetic totally chlorine-free (TCF) effluent degradability in batch and continuously operating reactors was evaluated. Under batch treatment, the addition of EDTA and Fe-EDTA complex was studied in the range of 80 to 320 mg l(-1). Under continuously operated reactors, the Fe-EDTA complex concentration varied from 20 to 80 mg l(-1), and the hydraulic retention time (HRT) varied from 48 to 24 h. Sludge oxygen uptake rate (OUR) and chemical oxygen demand (COD) removal decreased when EDTA concentration increased in the influent under batch treatment; however, this inhibitory effect was reduced by the addition of Fe-EDTA complex. Without the addition of EDTA, COD removal decreased from 71% to 8%. The most efficient EDTA removal treatment (almost 10%) was the treatment of 80 mg l(-1) Fe-EDTA. Under continuously operated reactors, COD removal was greater than 57% in the synthetic TCF effluent with a Fe-EDTA concentration that varied from 20 to 80 mg l(-1); however, EDTA removal was lower than 25% in all cases. Synthetic TCF effluent with a Fe -EDTA concentration higher than 80 mg l(-1) could not be treated by the activated sludge treatment due to EDTA's inhibitory effect on the sludge.

Substrates and oxygen dependent citric acid production by Yarrowia lipolytica: insights through transcriptome and fluxome analyses.

PubMed

Sabra, Wael; Bommareddy, Rajesh Reddy; Maheshwari, Garima; Papanikolaou, Seraphim; Zeng, An-Ping

2017-05-08

Unlike the well-studied backer yeast where catabolite repression represents a burden for mixed substrate fermentation, Yarrowia lipolytica, an oleaginous yeast, is recognized for its potential to produce single cell oils and citric acid from different feedstocks. These versatilities of Y. lipolytica with regards to substrate utilization make it an attractive host for biorefinery application. However, to develop a commercial process for the production of citric acid by Y. lipolytica, it is necessary to better understand the primary metabolism and its regulation, especially for growth on mixed substrate. Controlling the dissolved oxygen concentration (pO 2 ) in Y. lipolytica cultures enhanced citric acid production significantly in cultures grown on glucose in mono- or dual substrate fermentations, whereas with glycerol as mono-substrate no significant effect of pO 2 was found on citrate production. Growth on mixed substrate with glucose and glycerol revealed a relative preference of glycerol utilization by Y. lipolytica. Under optimized conditions with pO 2 control, the citric acid titer on glucose in mono- or in dual substrate cultures was 55 and 50 g/L (with productivity of 0.6 g/L*h in both cultures), respectively, compared to a maximum of 18 g/L (0.2 g/L*h) with glycerol in monosubstrate culture. Additionally, in dual substrate fermentation, glycerol limitation was found to trigger citrate consumption despite the presence of enough glucose in pO 2 -limited culture. The metabolic behavior of this yeast on different substrates was investigated at transcriptomic and 13 C-based fluxomics levels. Upregulation of most of the genes of the pentose phosphate pathway was found in cultures with highest citrate production with glucose in mono- or in dual substrate fermentation with pO 2 control. The activation of the glyoxylate cycle in the oxygen limited cultures and the imbalance caused by glycerol limitation might be the reason for the re-consumption of citrate in

78 FR 34648 - Citric Acid and Certain Citrate Salts: Preliminary Results of Countervailing Duty Administrative...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-10

... Citrate Salts: Preliminary Results of Countervailing Duty Administrative Review; 2011 AGENCY: Import... December 31, 2011. These preliminary results cover RZBC Group Shareholding Co., Ltd., RZBC Co., Ltd., RZBC... Memorandum for the Preliminary Results of the Countervailing Duty Administrative Review: Citric Acid and...

Structure elucidation and quantification of impurities formed between 6-aminocaproic acid and the excipients citric acid and sorbitol in an oral solution using high-resolution mass spectrometry and nuclear magnetic resonance spectroscopy.

PubMed

Schou-Pedersen, Anne Marie V; Cornett, Claus; Nyberg, Nils; Østergaard, Jesper; Hansen, Steen Honoré

2015-03-25

Concentrated solutions containing 6-aminocaproic acid and the excipients citric acid and sorbitol have been studied at temperatures of 50°C, 60°C, 70°C and 80°C as well as at 20°C. It has previously been reported that the commonly employed citric acid is a reactive excipient, and it is therefore important to thoroughly investigate a possible reaction between 6-aminocaproic acid and citric acid. The current study revealed the formation of 3-hydroxy-3,4-dicarboxy-butanamide-N-hexanoic acid between 6-aminocaproic acid and citric acid by high-resolution mass spectrometry (HRMS) and nuclear magnetic resonance spectroscopy (NMR). Less than 0.03% of 6-aminocaproic acid was converted to 3-hydroxy-3,4-dicarboxy-butanamide-N-hexanoic acid after 30 days of storage at 80°C. Degradation products of 6-aminocaproic acid were also observed after storage at the applied temperatures, e.g., dimer, trimer and cyclized 6-aminocaproic acid, i.e., caprolactam. No reaction products between D-sorbitol and 6-aminocaproic acid could be observed. 3-Hydroxy-3,4-dicarboxy-butanamide-N-hexanoic acid, dimer and caprolactam were also observed after storage at 20°C for 3 months. The findings imply that an oral solution of 6-aminocaproic acid is relatively stable at 20°C at the pH values 4.00 and 5.00 as suggested in the USP for oral formulations. Compliance with the ICH guideline Q3B is expected. Copyright © 2015 Elsevier B.V. All rights reserved.

Simple citric acid-catalyzed surface esterification of cellulose nanocrystals.

PubMed

Ávila Ramírez, Jhon Alejandro; Fortunati, Elena; Kenny, José María; Torre, Luigi; Foresti, María Laura

2017-02-10

A simple straightforward route for the surface esterification of cellulose nanocrystals (CNC) is herein proposed. CNC obtained from microcrystalline cellulose were acetylated using as catalyst citric acid, a α-hydroxy acid present in citrus fruits and industrially produced by certain molds in sucrose or glucose-containing medium. No additional solvent was added to the system; instead, the acylant (acetic anhydride) was used in sufficient excess to allow CNC dispersion and proper suspension agitation. By tuning the catalyst load, CNC with two different degree of substitution (i.e. DS=0.18 and 0.34) were obtained. Acetylated cellulose nanocrystals were characterized in terms of chemical structure, crystallinity, morphology, thermal decomposition and dispersion in a non-polar solvent. Results illustrated for the first time the suitability of the protocol proposed for the simple surface acetylation of cellulose nanocrystals. Copyright © 2016 Elsevier Ltd. All rights reserved.

EDTA-assisted Pb phytoextraction.

PubMed

Saifullah; Meers, E; Qadir, M; de Caritat, P; Tack, F M G; Du Laing, G; Zia, M H

2009-03-01

Pb is one of the most widespread and metal pollutants in soil. It is generally concentrated in surface layers with only a minor portion of the total metal found in soil solution. Phytoextraction has been proposed as an inexpensive, sustainable, in situ plant-based technology that makes use of natural hyperaccumulators as well as high biomass producing crops to help rehabilitate soils contaminated with heavy metals without destructive effects on soil properties. The success of phytoextraction is determined by the amount of biomass, concentration of heavy metals in plant, and bioavailable fraction of heavy metals in the rooting medium. In general, metal hyperaccumulators are low biomass, slow growing plant species that are highly metal specific. For some metals such as Pb, there are no hyperaccumulator plant species known to date. Although high biomass-yielding non-hyperaccumulator plants lack an inherent ability to accumulate unusual concentrations of Pb, soil application of chelating agents such as EDTA has been proposed to enhance the metal concentration in above-ground harvestable plant parts through enhancing the metal solubility and translocation from roots to shoots. Leaching of metals due to enhanced mobility during EDTA-assisted phytoextraction has been demonstrated as one of the potential hazards associated with this technology. Due to environmental persistence of EDTA in combination with its strong chelating abilities, the scientific community is moving away from the use of EDTA in phytoextraction and is turning to less aggressive alternative strategies such as the use of organic acids or more degradable APCAs (aminopolycarboxylic acids). We have therefore arrived at a point in phytoremediation research history in which we need to distance ourselves from EDTA as a proposed soil amendment within the context of phytoextraction. However, valuable lessons are to be learned from over a decade of EDTA-assisted phytoremediation research when considering the

Performance, kinetics, and equilibrium of methylene blue adsorption on biochar derived from eucalyptus saw dust modified with citric, tartaric, and acetic acids.

PubMed

Sun, Lei; Chen, Dongmei; Wan, Shungang; Yu, Zebin

2015-12-01

Biochar derived from eucalyptus saw dust modified with citric, tartaric, and acetic acids at low temperatures was utilized as adsorbent to remove methylene blue (MB) from aqueous solutions. Fourier transform infrared spectroscopy analysis showed that the carboxyl group was introduced on the biochar surface. Adsorption experiment data indicated that eucalyptus saw dust modified with citric acid showed higher MB adsorption efficiency than that modified with tartaric and acetic acids. Pseudo-second-order kinetics was the most suitable model for describing MB adsorption on biochar compared with pseudo-first-order, Elovich, and intraparticle diffusion models. The calculated values of ΔG(0) and ΔH(0) indicated the spontaneous and endothermic nature of the adsorption process. MB adsorption on biochar followed the Langmuir isotherm. The maximum adsorption capacities for eucalyptus saw dust modified with citric, tartaric, and acetic acids were 178.57, 99.01, and 29.94 mg g(-1), respectively, at 35°C. Copyright © 2015 Elsevier Ltd. All rights reserved.

Enhanced citric acid production in aspergillus with inactivated asparagine-linked glycosylation protein 3 (ALG3), and/or increased laeA expression

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dai, Ziyu; Baker, Scott E.

Provided herein are fungi, such as Aspergillus niger, having a dolichyl-P-Man:Man(5)GlcNAc(2)-PP-dolichyl mannosyltransferase (Alg3) gene genetic inactivation, increased expression of a loss of aflR expression A (Lae), or both. In some examples, such mutants have several phenotypes, including an increased production of citric acid relative to the parental strain. Methods of using the disclosed fungi to make citric acid are also provided, as are compositions and kits including the disclosed fungi.

Efficacy of citric acid denture cleanser on the Candida albicans biofilm formed on poly(methyl methacrylate): effects on residual biofilm and recolonization process

PubMed Central

2014-01-01

Background It is well known that the use of denture cleansers can reduce Candida albicans biofilm accumulation; however, the efficacy of citric acid denture cleansers is uncertain. In addition, the long-term efficacy of this denture cleanser is not well established, and their effect on residual biofilms is unknown. This in vitro study evaluated the efficacy of citric acid denture cleanser treatment on C. albicans biofilm recolonization on poly(methyl methacrylate) (PMMA) surface. Methods C. albicans biofilms were developed for 72 h on PMMA resin specimens (n = 168), which were randomly assigned to 1 of 3 cleansing treatments (CTs) overnight (8 h). CTs included purified water as a control (CTC) and two experimental groups that used either a 1:5 dilution of citric acid denture cleanser (CT5) or a 1:8 dilution of citric acid denture cleanser (CT8). Residual biofilms adhering to the specimens were collected and quantified at two time points: immediately after CTs (ICT) and after cleaning and residual biofilm recolonization (RT). Residual biofilms were analyzed by quantifying the viable cells (CFU/mL), and biofilm architecture was evaluated by confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). Denture cleanser treatments and evaluation periods were considered study factors. Data were analyzed using two-way ANOVA and Tukey’s Honestly Significant Difference (HSD) test (α = 0.05). Results Immediately after treatments, citric acid denture cleansing solutions (CT5 and CT8) reduced the number of viable cells as compared with the control (p < 0.01). However, after 48 h, both CT groups (CT5 and CT8) showed biofilm recolonization (p < 0.01). Residual biofilm recolonization was also detected by CLSM and SEM analysis, which revealed a higher biomass and average biofilm thickness for the CT8 group (p < 0.01). Conclusion Citric acid denture cleansers can reduce C. albicans biofilm accumulation and cell viability. However, this

Efficacy of citric acid denture cleanser on the Candida albicans biofilm formed on poly(methyl methacrylate): effects on residual biofilm and recolonization process.

PubMed

Faot, Fernanda; Cavalcanti, Yuri Wanderley; Mendonça e Bertolini, Martinna de; Pinto, Luciana de Rezende; da Silva, Wander José; Cury, Altair Antoninha Del Bel

2014-06-23

It is well known that the use of denture cleansers can reduce Candida albicans biofilm accumulation; however, the efficacy of citric acid denture cleansers is uncertain. In addition, the long-term efficacy of this denture cleanser is not well established, and their effect on residual biofilms is unknown. This in vitro study evaluated the efficacy of citric acid denture cleanser treatment on C. albicans biofilm recolonization on poly(methyl methacrylate) (PMMA) surface. C. albicans biofilms were developed for 72 h on PMMA resin specimens (n = 168), which were randomly assigned to 1 of 3 cleansing treatments (CTs) overnight (8 h). CTs included purified water as a control (CTC) and two experimental groups that used either a 1:5 dilution of citric acid denture cleanser (CT5) or a 1:8 dilution of citric acid denture cleanser (CT8). Residual biofilms adhering to the specimens were collected and quantified at two time points: immediately after CTs (ICT) and after cleaning and residual biofilm recolonization (RT). Residual biofilms were analyzed by quantifying the viable cells (CFU/mL), and biofilm architecture was evaluated by confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). Denture cleanser treatments and evaluation periods were considered study factors. Data were analyzed using two-way ANOVA and Tukey's Honestly Significant Difference (HSD) test (α = 0.05). Immediately after treatments, citric acid denture cleansing solutions (CT5 and CT8) reduced the number of viable cells as compared with the control (p < 0.01). However, after 48 h, both CT groups (CT5 and CT8) showed biofilm recolonization (p < 0.01). Residual biofilm recolonization was also detected by CLSM and SEM analysis, which revealed a higher biomass and average biofilm thickness for the CT8 group (p < 0.01). Citric acid denture cleansers can reduce C. albicans biofilm accumulation and cell viability. However, this CT did not prevent biofilm recolonization.

K2-EDTA and K3-EDTA Greiner Tubes for HbA1c Measurement.

PubMed

Vrtaric, Alen; Filipi, Petra; Hemar, Marina; Nikolac, Nora; Simundic, Ana-Maria

2016-02-01

To determine whether K2-ethylenediaminetetraacetic acid (EDTA) and K3-EDTA Greiner tubes could be used interchangeably for glycosylated hemoglobin, type A1C (HbA1c) measurement via the Abbott Laboratories ARCHITECT chemiluminescent microparticle HbA1c assay on the ARCHITECT i2000SR immunoanalyzer at our university hospital. We drew blood from a total of 45 outpatients into plastic Greiner Vacuette tubes, some of which were lined with K2-EDTA and others with K3-EDTA anticoagulant. Data are presented as median and interquartile range values. We used the Wilcoxon test and Passing-Bablok regression for tube comparison. For K2-EDTA tubes median HbA1c concentration was 54 mmol/mol (41 to 71 mmol/mol) and for K3-EDTA tubes 56 mmol/mol (43 to 69 mmol/mol). There was no statistically significant difference between K2-EDTA and K3-EDTA (bias= -1.29 mmol/mol; P = 0.24). Passing-Bablok regression showed that there is no constant and proportional error: y = -0.23 (95% CI[-3.52 to 0.69]) + 1.00( 95% CI[0.98 to 1.06]) x. In this study, we provide evidence for the lack of any clinically and statistically significant bias between K2-EDTA and K3-EDTA HbA1c measurements. Thus, Greiner tubes lined with K2-EDTA and those lined with K3-EDTA can safely be used interchangeably to measure HbA1c via the Abbott Laboratories ARCHITECT assay. © American Society for Clinical Pathology, 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

The effect of citric acid on morphology and photoluminescence properties of white light emitting ZnO-SiO2 nanocomposites

NASA Astrophysics Data System (ADS)

Sivakami, R.; Thiyagarajan, P.

2016-07-01

The white light emitting ZnO-SiO2 nanocomposites were synthesized by sol-gel combustion method using zinc nitrate, citric acid and tetraethoxysilane. To analyze the effect of fuel content on the photoluminescence properties of ZnO-SiO2 nanocomposites, the citric acid content was varied as 1, 5, and 10 moles with respect to one mole of zinc. The SEM images of the nanocomposites revealed the spherical, flower and platelet like morphology with variation in citric acid content and annealing temperatures. The ZnO-SiO2 nanocomposites prepared with various Zn:CA ratio excited at UV (280 nm), near UV (365 nm), violet (405 nm) and blue (465 nm) wavelength showed blue and greenish-yellow emission. Among all ratios, the ZnO-SiO2 nanocomposites with Zn:CA - 1:1 ratio showed the intense broad band emission compared to Zn:CA - 1:5 and 1:10 values. This particular composition of sample excited under violet (405 nm) LED source shows white light, as confirmed by the CIE chromaticity coordinates (x = 0.342, y = 0.318).

Influence of calcium on fungal growth, hyphal morphology and citric acid production in Aspergillus niger.

PubMed

Pera, L M; Callieri, D A

1997-01-01

Addition of 0.5 g/L CaCl2 to the fermentation medium lowered the final biomass dry mass by 35% and increased the uptake of phosphate and sucrose, and the production of citric acid by 15, 35 and 50%, respectively. In a medium deprived of Ca2+ the microorganism displayed both a pelleted and a filamentous form of growth, the hyphae being scarcely branched, without bulbous cells. An addition of Ca2+ induced a pelleted form of growth, highly branched hyphae and numerous bulbous cells. Bulbous cells growing in the presence of Ca2+ exhibited cell walls composed of laminated layers, and featured vesicles associated with the wall and/or the cell membrane, containing numerous inclusions. The cytotoxic effect of high concentrations of citric acid in the medium as well as an increase of the activity of N-acetyl-beta-D-glucosaminidase, a lytic enzyme, might be involved in these morphological changes.

Preliminary study on preparation of BCNO phosphor particles using citric acid as carbon source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nuryadin, Bebeh W.; Pratiwi, Tripuspita; Faryuni, Irfana D.

A citric acid was used as a carbon source in the preparation of boron carbon oxy-nitride (BCNO) phosphor particles by a facile process. The preparation process was conducted at relatively low temperature 750 °C and at ambient pressure. The prepared BCNO phosphors showed a high photoluminescence (PL) performance at peak emission wavelength of 470 nm under excitation by a UV light 365 nm. The effects of carbon/boron and nitrogen/boron molar ratios on the PL properties were also investigated. The result showed that the emission spectra with a wavelength peak ranging from 444 nm to 496 nm can be obtained bymore » varying carbon/boron ratios from 0.1 to 0.9. In addition, the observations showed that the BCNO phosphor material has two excitation peaks located at the 365 nm (UV) and 420 nm (blue). Based on these observations, we believe that the citric acid derived BCNO phosphor particles can be a promising inexpensive material for phosphor conversion-based white LED.« less

The effect of combination of sugar palm fruit, carrageenan, and citric acid on mechanical properties of biodegradable film

NASA Astrophysics Data System (ADS)

Rinanda, S. A.; Nastabiq, M.; Raharjo, S. H.; Hayati, S. K.; Yaqin, M. A.; Ratnawati

2017-11-01

Biodegradable film is a type of plastic material that can be degraded naturally and is usually made of organic material. The material commonly used is polysaccharides. The purpose of this study is to observe the effect of the combination of sugar palm fruit, carrageenan, and citric acid (CA) on the mechanical properties of the biodegradable films, such as tensile strength, elongation and film thickness. The experiment begins with dissolving the sugar palm fruit porridge and carrageenan with ratios of 1:0, 3:1, 2:1, 1:1 in water. The mixture was heated using a heater and magnetic stirrer at 80° C for 10 minutes. Glycerol and citric acid (CA) were added to the solution and stirred for 5 minutes. Each film solution was printed on a modified acrylic and, dried for 18 hours in an oven at 55° C. The formed film layer was then removed from the acrylic mold and inserted in a desiccatorsat 23° C for 1 hour. Then the film analyzed for its tensile strength, elongation using Dynamic Mechanical Thermal Analysis (DMTA), and thickness. The optimum result shown by sugar palm fruit and carrageenan ratio of 1:1 with 1% citric acid (CA).

Suicide by plastic bag suffocation combined with the mixture of citric acid and baking soda in an adolescent.

PubMed

Murakami, Keishu; Kawaguchi, Takashi; Hashizume, Yumiko; Kitamura, Kengo; Okada, Misato; Okumoto, Kohei; Sakamoto, Shoich; Ishida, Yuko; Nosaka, Mizuho; Kimura, Akihiko; Takatsu, Akihiro; Kondo, Toshikazu

2018-05-22

We describe a case of suicidal asphyxiation using a plastic bag combined with carbon dioxide (CO 2 ) gas. A 20-year-old male, whose head was covered with a plastic bag, was found dead in his room. In the plastic bag, there were two glass-made cups containing liquid-like substance. Through crime scene investigation by police staffs, a bottle of citric acid and a box of baking soda were also discovered in his room. The forensic autopsy revealed that there were neither lesions nor injuries in all of the organs. Moreover, any drugs and poisons could not be detected in blood samples. Based on autopsy findings and crime scene investigation, the cause of death was diagnosed as acute asphyxia due to CO 2 intoxication by the mixture of citric acid with baking soda in the plastic bag. To the best of our knowledge, there are no medical literatures describing plastic bag suffocation combined with CO 2 gas generated from citric acid and baking soda, which has been widely distributed as suicidal means through websites. This case report promotes forensic pathologists and medical coroners to emphasize that the Internet has a crucial role on a source of suicidal information or a promoter of suicide all over the world.

Chelating effect of citric acid is negligible for development of enamel erosions.

PubMed

Azadi-Schossig, Parastu; Becker, Klaus; Attin, Thomas

2016-09-01

Citric acid (CA) is a component in beverages responsible for dental erosion. The aim of this study was to examine the influence of CA with different pH, titratable acid and buffer capacity (ß), and the impact of the chelating effect of CA on development of enamel erosions. In a superfusion model, hydroxy apatite (HAp) dissolution of bovine enamel was measured in four experiments (EXP 1-4) with 27 experimental groups (n = 8 per group). The samples were superfused with different CA variations and respective controls. EXP-1: Dilution series of HCl (pH 2.15-3.02). EXP-2: Dilution series of natural CA (56-1.75 mmol l(-1); pH 2.15-3.02). EXP-3: CA solutions (56 and 14 mmol l(-1), ß: 39.7 and 10.2 mmol l(-1) pH(-1), respectively) with different titratable acidity at equal pH values. EXP-4: CA concentrations (56-1.75 mmol l(-1)) neutralized to pH 7. CA led to higher HAp-dissolution than HCl. With higher pH, the difference in HAp-dissolution rate between the two acids became increasingly smaller. At equal pH, HAp-dissolution was higher for the CA with the higher amount of titratable acid. However, no clear correlation between erosion and titratable acid or ß could be found. Only minimal amounts of HAp were dissolved by neutralized CA compared to CA with natural pH. Under the chosen conditions chelating effects of CA do not have a relevant influence of HAp-dissolution of enamel. Moreover, amount of HAp-dissolution by CA is not attributed to a single factor alone. The interplay between the different parameters of CA seems to be responsible for its erosive potential. The erosive potential of solutions containing citric acid with unknown concentrations could not be predicted using a single parameter alone, and should at best determined in experimental set-ups.

Olodaterol Attenuates Citric Acid-Induced Cough in Naïve and Ovalbumin-Sensitized and Challenged Guinea Pigs

PubMed Central

Wex, Eva; Bouyssou, Thierry

2015-01-01

Excessive coughing is a common feature of airway diseases. Different G-protein coupled receptors, including β2-adrenergic receptors (β2-AR), have been implicated in the molecular mechanisms underlying the cough reflex. However, the potential antitussive property of β2-AR agonists in patients with respiratory disease is a matter of ongoing debate. The aim of our study was to test the efficacy of the long-acting β2-AR agonist olodaterol with regard to its antitussive property in a pre-clinical model of citric acid-induced cough in guinea pigs and to compare the results to different clinically relevant β2-AR agonists. In our study β2-AR agonists were intratracheally administered, as dry powder, into the lungs of naïve or ovalbumin-sensitized guinea pigs 15 minutes prior to induction of cough by exposure to citric acid. Cough events were counted over 15 minutes during the citric acid exposure. Olodaterol dose-dependently inhibited the number of cough events in naïve and even more potently and with a greater maximal efficacy in ovalbumin-sensitized guinea pigs (p < 0.01). Formoterol and salmeterol showed a trend towards reducing cough. On the contrary, indacaterol demonstrated pro-tussive properties as it significantly increased the number of coughs, both in naïve and ovalbumin-sensitized animals (p < 0.001). In conclusion, olodaterol, at doses eliciting bronchodilation, showed antitussive properties in a model of citric acid-induced cough in naïve and ovalbumin-sensitized guinea pigs. This is in agreement with pre-clinical and clinical studies showing antitussive efficacy of β2-AR agonists. Indacaterol increased the number of coughs in this model, which concurs with clinical data where a transient cough has been observed after indacaterol inhalation. While the antitussive properties of β2-AR agonists can be explained by their ability to lead to the cAMP-induced hyperpolarization of the neuron membrane thereby inhibiting sensory nerve activation and the

Coagulation of bitumen with kaolinite in aqueous solutions containing Ca2+, Mg2+ and Fe3+: effect of citric acid.

PubMed

Gan, Weibing; Liu, Qi

2008-08-01

Heterocoagulation experiments of kaolinite with solvent-diluted-bitumen were carried out to investigate the effect of hydrolyzable metal cations and citric acid on the liberation of bitumen from kaolinite. The adsorption of Ca(2+) and Mg(2+) on kaolinite, and zeta potentials of kaolinite and bitumen droplets in solutions containing 10(-3)mol/L of Ca(2+), Mg(2+) and Fe(3+) with or without citric acid were also measured. It was found that the heterocoagulation of bitumen with kaolinite was enhanced in the presence of the metal cations from pH 7 to pH 10.5, accompanied by a decrease in the magnitude of the zeta potentials and an increase in the adsorption of the metal cations on kaolinite and possibly on bitumen droplets. The addition of 5 x 10(-4)mol/L citric acid reduced the degree of coagulation from 90% to less than 40% in the presence of 10(-3)mol/L Ca(2+) and Mg(2+) cations at pH approximately 10, and at pH approximately 8 for Fe(3+). It was found that hydrolyzable metal cations enhanced bitumen-kaolinite interactions through electrical double layer compression and specific adsorption of the metal hydrolysis species on the surface of kaolinite. The effect of metal cations was removed by citric acid through formation of metal-citrate complexes and/or the adsorption of citrate anions, which restored the zeta potentials of both kaolinite and bitumen. Therefore, electrostatic attraction or repulsion was responsible for the coagulation or dispersion of kaolinite particles from bitumen droplets in the tested system.

The application of EDTA in drug delivery systems: doxorubicin liposomes loaded via NH4EDTA gradient

PubMed Central

Song, Yanzhi; Huang, Zhenjun; Song, Yang; Tian, Qingjing; Liu, Xinrong; She, Zhennan; Jiao, Jiao; Lu, Eliza; Deng, Yihui

2014-01-01

The applications of ethylenediaminetetraacetic acid (EDTA) have been expanded from the treatment of heavy metal poisoning to chelation therapies for atherosclerosis, heart disease, and cancers, in which EDTA reduces morbidity and mortality by chelating toxic metal ions. In this study, EDTA was used in a drug delivery system by adopting an NH4EDTA gradient method to load doxorubicin into liposomes with the goal of increasing therapeutic effects and decreasing drug-related cytotoxicity. The particle size of the optimum NH4EDTA gradient liposomes was 79.4±1.87 nm, and the entrapment efficiency was 95.54%±0.59%. In vitro studies revealed that liposomes prepared using an NH4EDTA gradient possessed long-term stability and delayed drug release. The in vivo studies also showed the superiority of the new doxorubicin formulation. Compared with an equivalent drug dose (5 mg/kg) prepared by (NH4)2SO4 gradient, NH4EDTA gradient liposomes showed no significant differences in tumor inhibition ratio, but cardiotoxicity and liposome-related immune organ damage were lower, and no drug-related deaths were observed. These results show that use of the NH4EDTA gradient method to load doxorubicin into liposomes could significantly reduce drug toxicity without influencing antitumor activity. PMID:25120359

[Effect of citric acid stimulation on salivary alpha-amylase, total protein, salivary flow rate and pH value in Pi deficiency children].

PubMed

Yang, Ze-min; Chen, Long-hui; Lin, Jing; Zhang, Min; Yang, Xiao-rong; Chen, Wei-wen

2015-02-01

To compare the effect of citric acid stimulation on salivary alpha-amylase (sAA), total protein (TP), salivary flow rate, and pH value between Pi deficiency (PD) children and healthy children, thereby providing evidence for Pi controlling saliva theory. Twenty PD children were recruited, and 29 healthy children were also recruited at the same time. Saliva samples from all subjects were collected before and after citric acid stimulation. The sAA activity and amount, TP contents, salivary flow rate, and pH value were determined and compared. (1) Citric acid stimulation was able to significantly increase salivary flow rate, pH value, sAA activities, sAA specific activity and sAA amount (including glycosylated and non-glycosylated sAA amount) in healthy children (P<0.05), while it could markedly increase salivary flow rate, pH value, and glycosylated sAA levels in PD children (P<0.05); (2) Although there was no statistical difference in determined salivary indices between the two groups (P>0.05), salivary indices except salivary flow rate and glycosylated sAA levels decreased more in PD children. There was statistical difference in sAA activity ratio, sAA specific activity ratio, and the ratio of glycosylated sAA levels between PD children and healthy children (P<0.05). PD children had decreased response to citric acid stimulation.

Effect of sodium chloride and citric acid on growth and toxin production by A. caviae and A. sobria at moderate and low temperatures.

PubMed

Abu-Ghazaleh, B M

2000-10-01

The effect of sodium chloride and citric acid on hemolysin and caseinase production by Aeromonas caviae and Aeromonas sobria at 32 degrees C and 5 degrees C was investigated. At 32 degrees C, although both strains were tolerant to 3% NaCl in TSB, the production of caseinase was decreased in the presence of 1-3% NaCl, and the production of hemolysin was abolished by 2-3% NaCl. Citric acid (0.03%) was less effective than NaCl in reducing hemolysin and caseinase production by both strains at 32 degrees C. A combination of low temperature (5 degrees C) and citric acid treatment reduced hemolysin and caseinase production by both strains. A combination of low temperature (5 degrees C) and NaCl (3%) treatment was the most effective procedure in reducing growth and hemolysin and caseinase production by the tested strains.

A comparative evaluation of smear layer removal by using edta, etidronic acid, and maleic acid as root canal irrigants: An in vitro scanning electron microscopic study

PubMed Central

Kuruvilla, Aby; Jaganath, Bharath Makonahalli; Krishnegowda, Sahadev Chickmagaravalli; Ramachandra, Praveen Kumar Makonahalli; Johns, Dexton Antony; Abraham, Aby

2015-01-01

Aim: The purpose of this study is to evaluate and compare the efficacy of 17% EDTA, 18% etidronic acid, and 7% maleic acid in smear layer removal using scanning electron microscopic image analysis. Materials and Methods: Thirty, freshly extracted mandibular premolars were used. The teeth were decoronated to obtain working length of 17mm and instrumentation up to 40 size (K file) with 2.5% NaOCl irrigation between each file. The samples were divided into Groups I (17% ethylenediaminetetraacetic acid (EDTA)), II (18% etidronic acid), and III (7% maleic acid) containing 10 samples each. Longitudinal sectioning of the samples was done. Then the samples were observed under scanning electron microscope (SEM) at apical, middle, and coronal levels. The images were scored according to the criteria: 1. No smear layer, 2. moderate smear layer, and 3 heavy smear layer. Statistical Analysis: Data was analyzed statistically using Kruskal–Wallis analysis of variance (ANOVA) followed by Mann-Whitney U test for individual comparisons. The level for significance was set at 0.05. Results: The present study showed that all the three experimental irrigants removed the smear layer from different tooth levels (coronal, middle, and apical). Final irrigation with 7% maleic acid is more efficient than 17% EDTA and 18% etidronic acid in the removal of smear layer from the apical third of root canal. PMID:26069414

Influence of EDTA in poly(acrylic acid) binder for enhancing electrochemical performance and thermal stability of silicon anode

NASA Astrophysics Data System (ADS)

Lee, Sun-Young; Choi, Yunju; Hong, Kyong-Soo; Lee, Jung Kyoo; Kim, Ju-Young; Bae, Jong-Seong; Jeong, Euh Duck

2018-07-01

The crucial roles of ethylenediaminetetraacetic acid (EDTA) in the poly(acrylic acid) (PAA)-binder system were investigated for the high electrochemical performance silicon anode in lithium-ion batteries. The EDTA supports the construction of a mechanically robust network through the formation of sbndCOOH linkage with the SiO2 layer of the Si nanoparticles. The mixture of the PAA/EDTA binder and the conductive agent exhibited an improved elastic modulus and peeling strength. The creation of hydrogen fluoride (HF) was effectively suppressed through the elimination of the H2O. An H2O-phosphorous pentafluoride (PF5) reaction, which is known for its use in the etching of metal oxides including its creation of the solid electrolyte interphase (SEI) layer, generates the HF. A remarkably sound cyclability with a discharge capacity of 2540 mA h g-1 was achieved as a result of the synergistic effect between robust mechanical properties and suppression of the HF creation for the stability of the SEI layer.

Preservation of urine free catecholamines and their free O-methylated metabolites with citric acid as an alternative to hydrochloric acid for LC-MS/MS-based analyses.

PubMed

Peitzsch, Mirko; Pelzel, Daniela; Lattke, Peter; Siegert, Gabriele; Eisenhofer, Graeme

2016-01-01

Measurements of urinary fractionated metadrenalines provide a useful screening test to diagnose phaeochromocytoma. Stability of these compounds and their parent catecholamines during and after urine collection is crucial to ensure accuracy of the measurements. Stabilisation with hydrochloric acid (HCl) can promote deconjugation of sulphate-conjugated metadrenalines, indicating a need for alternative preservatives. Urine samples with an intrinsically acidic or alkaline pH (5.5-6.9 or 7.1-8.7, respectively) were used to assess stability of free catecholamines and their free O-methylated metabolites over 7 days of room temperature storage. Stabilisation with HCl was compared with ethylenediaminetetraacetic acid/metabisulphite and monobasic citric acid. Catecholamines and metabolites were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Free catecholamines and their O-methylated metabolites were stable in acidic urine samples over 7 days of room temperature storage, independent of the presence or absence of any stabilisation method. In contrast, free catecholamines, but not the free O-methylated metabolites, showed rapid degradation within 24 h and continuing degradation over 7 days in urine samples with an alkaline pH. Adjustment of alkaline urine samples to a pH of 3-5 with HCl or 4.8-5.4 with citric acid completely blocked degradation of catecholamines. Ethylenediaminetetraacetic acid/metabisulphite, although reducing the extent of degradation of catecholamines in alkaline urine, was largely ineffectual as a stabiliser. Citric acid is equally effective as HCl for stabilisation of urinary free catecholamines and minimises hazards associated with use of strong inorganic acids while avoiding deconjugation of sulphate-conjugated metabolites during simultaneous LC-MS/MS measurements of free catecholamines and their free O-methylated metabolites.

EDTA: a synthetic draw solute for forward osmosis.

PubMed

Lutchmiah, Kerusha; Post, Jan W; Rietveld, Luuk C; Cornelissen, Emile R

2014-01-01

The draw solution is the driving force of the forward osmosis (FO) process; however, the solute loss of the draw solute to the feed side is a general, financial limitation for most applications. The anthropogenic amino acid ethylenediaminetetraacetic acid (EDTA) was investigated as a draw solution for FO. At concentrations of approximately 1.0 osmol/kg, EDTA demonstrated comparable water fluxes (Jv = 5.29 L/m(2) h) to the commonly used salt, NaCl (Jv = 4.86 L/m(2) h), and both produced better water fluxes than glucose (Jv = 3.46 L/m(2) h). EDTA showed the lowest solute loss with Js (reverse solute loss or solute leakage) = 0.54 g/m(2) h. The molecular weight, degree of ionisation and charge of EDTA played a major role in this efficiency and EDTA was therefore well rejected by the membrane, showing a low Js/Jv ratio of 0.10 g/L. Owing to the low solute loss of EDTA and its resistance to biodegradation, this compound has the potential to be used as a draw solute for FO during long periods without requiring much replenishment.

Interaction between chlorhexidine digluconate and EDTA.

PubMed

Rasimick, Brian J; Nekich, Michelle; Hladek, Megan M; Musikant, Barry L; Deutsch, Allan S

2008-12-01

The combination of chlorhexidine and EDTA produces a white precipitate. The aim of this study was to determine if the precipitate involves the chemical degradation of chlorhexidine. The precipitate was produced and redissolved in a known amount of dilute trifluoroacetic acid. The amount of chlorhexidine and EDTA present in the dissolved precipitate was determined by reverse-phase high performance liquid chromatography (HPLC) with ultraviolet detection at 288 nm. More than 90% of the precipitate's mass was found to be EDTA or chlorhexidine. The remainder is suspected to be water, gluconate, and sodium. Parachloroaniline, a potentially carcinogenic decomposition product of chlorhexidine, was not detected in the precipitate (the limit of detection was 1%). The molar ratio of chlorhexidine to EDTA in the precipitate was about 1.6 to 1. Based on the results, chlorhexidine forms a salt with EDTA rather than undergoing a chemical reaction.

Iodide oxidation and iodine reduction mediated by horseradish peroxidase in the presence of ethylenediaminetetraacetic acid (EDTA): the superoxide effect.

PubMed

Chang, H C; Bumpus, J A

2001-04-01

Ethylenediaminetetraacetic acid (EDTA) is an inhibitor of iodide (I-) oxidation that is catalyzed by horseradish peroxidase (HRP). HRP-mediated iodine (I2) reduction and triiodide (I3+) disappearance occur in the presence of this inhibitor. It is interesting that in the presence of EDTA, HRP produces superoxide radical, a reactive oxygen species that is required for iodine reduction. Substitution of potassium superoxide (KO2) or a biochemical superoxide generating system (xanthine/xanthine oxidase) for HRP and H2O2 in the reaction mixture also can reduce iodine to iodide. Thus, iodine reduction mediated by HRP occurs because HRP is able to mediate the formation of superoxide in the presence of EDTA and H2O2. Although superoxide is able to mediate iodine reduction directly, other competing reactions appear to be more important. For example, high concentrations (mM range) of EDTA are required for efficient iodine reduction in this system. Under such conditions, the concentration (microM range) of contaminating EDTA-Fe(III) becomes catalytically important. In the presence of superoxide, EDTA-Fe(III) is reduced to EDTA-Fe(II), which is able to reduce iodine and form triiodide rapidly. Also of importance is the fact that EDTA-Fe(II) reacts with hydrogen peroxide to form hydroxyl radical. Hydroxyl radical involvement is supported by the fact that a wide variety of hydroxyl radical (OH) scavengers can inhibit HRP dependent iodine reduction in the presence of EDTA and hydrogen peroxide.

Citric acid induced promoted dispersion of Pt on the support and enhanced catalytic activities for a Pt-based catalyst

NASA Astrophysics Data System (ADS)

Cheng, Tianqiong; Wang, Jianli; Wang, Suning; Cui, Yajuan; Zhang, Hailong; Yan, Shuang; Yuan, Shandong; Chen, Yaoqiang

2017-12-01

Citric acid (CA), as the chelating agent, was introduced to obtain the enhanced Pt dispersion and catalytic activities for the Pt-based catalysts supported on oxygen-storage material. The role and content of CA were investigated systematically. It was found that the citric acid-assisted catalysts showed better Pt dispersion and smaller nanoparticle size of Pt. Thus, the catalyst had lower reduction temperature, preferable thermostability and possessed more oxidation state of Pt species under the oxidation atmosphere. The citric acid-induced fresh catalysts were excellent to convert CO and the corresponding aged ones exhibited higher activities for the elimination of all the target pollutants. Among the aged catalysts, P2-a (the mole ratio of Pt/CA is 2:1) presented the best performance. Particularly, compared with the reference sample (Pc-a), the light-off temperatures (T50) of NO, HC and CO for P2-a decreased by 39 °C, 42 °C and 72 °C, respectively, and the full-conversion temperatures (T90) of NO, HC and CO for P2-a decreased by 44 °C, 44 °C and 48 °C, respectively. Therefore, this work provides a facile and valid method to manufacture advanced catalysts for purification of the vehicle exhaust in the future.

Evaluation of citric acid and GDL in the recovery at different pH levels of Clostridium sporogenes PA 3679 spores subjected to HTST treatment conditions.

PubMed

Silla Santos, M H; Torres Zarzo, J

1996-04-01

Spores of Clostridium sporogenes PA 3679 were treated at different temperatures (121, 126, 130 and 135 degrees C) in white asparagus purée (pH 5.8) and acidified with glucono-delta-lactone (GDL) and citric acid to pH levels of 5.5, 5.0 and 4.5. Afterwards, the spores were recovered in MPA3679 medium in various conditions: unacidified (pH 7.5), acidified with GDL (500 ppm) and acidified with citric acid (500 and 250 ppm) to pH levels of 6.5, 6.0 and 5.0. The results indicated that the pH levels, concentration and type of acid used act synergistically rather than independently. Citric acid has a stronger inhibiting effect than GDL on the recovery of C. sporogenes PA 3679 spores. At the higher heat treatments (130 and 135 degrees C) the major injury on the spores sensitize more than against the acids and low pH values.

Effect of citric acid on metals mobility in pruning wastes and biosolids compost and metals uptake in Atriplex halimus and Rosmarinus officinalis.

PubMed

Tapia, Y; Eymar, E; Gárate, A; Masaguer, A

2013-05-01

To assess metal mobility in pruning waste and biosolids compost (pH 6.9 and total concentration of metals in milligram per kilogram of Cd 1.9, Cu 132, Fe 8,513, Mn 192, Pb 81, and Zn 313), shrubs species Atriplex halimus and Rosmarinus officinalis were transplanted in this substrate and irrigated with citric acid (4 g L(-1), pH 2.9) and nutrient solution daily for 60 days. Citric acid significantly increased the concentrations of soluble Mn and Fe in the nutrient substrate solution measured by suction probes, while other metals did not vary in concentration (Cu and Zn) or were not observed at detectable levels (Cd and Pb). In plants, citric acid significantly increased the concentrations of Cu (2.7 ± 0.1-3.3 ± 0.1 mg kg(-1)), Fe (49.2 ± 5.2-76.8 ± 6.8 mg kg(-1)), and Mn (7.2 ± 1.1-11.4 ± 0.7 mg kg(-1)) in leaves of R. officinalis, whereas the concentration of only Mn (25.4 ± 0.3-42.2 ± 2.9 mg kg(-1)) was increased in A. halimus. Increasing Fe and Mn solubility by citric acid addition indicates the possibility of using it to improve plant nutrition. The mobility of metals in this substrate was influenced for the concentration of the metal, the degree of humification of organic matter and its high Fe content.

Structures of chloralide, ?-lactic acid chloralide, malic acid chloralide and citric acid chloralide

NASA Astrophysics Data System (ADS)

Koh, L. L.; Huang, H. H.; Chia, L. H. L.; Liang, E. P.

1995-06-01

The crystal and molecular structures of chloralide ( 1), D-lactic acid chloralide ( 2), malic acid chloralide ( 3) and citric acid chloralide ( 4) have been determined by X-ray diffraction methods. Compound 1 crystallizes in the monoclinic space group, {P2 1}/{c}, a = 6.201(2), b = 17.11(2), c = 10.357(6) Å, β = 95.21(4)°, Z = 4; compound 2 in the monoclinic space group P2 1, a = 7.600(4), b = 5.902(4), c = 9.743(6) Å, β = 99.20(5), Z = 2; compound 3 in the monoclinic space group {P2 1}/{c}, a = 16.500(6), b = 5.819(3), c = 10.120(4) Å, β = 91.41(3), Z = 4; compound 4 in the monoclinic space group {P2 1}/{c}, a = 12.041(3), b = 6.1190(10), c = 17.259(4) Å, β = 101.85(2), Z = 4. The five-membered ring systems of all the compounds are slightly twisted out-of-plane, that of compound 4 being the most puckered. The CCl 3 group is trans to the second CCl 3 group in 1, to the CH 3 group in 2 and to the CH 2COOH group in 3. The two CH 2COOH groups in 4 are disposed axially with respect to the ring. Dipole moment and Kerr constant data for D-lactic acid chloralide suggest a structure in solution which is consistent with the X-ray results. The IR spectra of 2, 3 and 4 are discussed in relation to the structures of these compounds.

Organic acids on the growth, anatomical structure, biochemical parameters and heavy metal accumulation of Iris lactea var. chinensis seedling growing in Pb mine tailings.

PubMed

Han, Yu-Lin; Huang, Su-Zhen; Yuan, Hai-Yan; Zhao, Jiu-Zhou; Gu, Ji-Guang

2013-08-01

The effect of citric acid (CA) and ethylene diamine tetraacetic acid (EDTA) on the growth, anatomical structure, physiological responses and lead (Pb) accumulation of Iris lactea var. chinensis seedling growing in Pb mine tailings for 30 days were studied. Results showed that the dry weights (DW) of roots decreased significantly under both levels of CA. The DWs of leaves and roots treated with 2 mmol/kg EDTA decreased significantly and were 23 and 54 %, respectively, lower than those of the control. The tolerant indexes of I. lactea var. chinensis under all treatments of organic acids were lower than control. The root tip anatomical structure was little affected under the treatments of 2 mmol/kg CA and 2 mmol/kg EDTA compared with control. However, the formation of photosynthesizing cells was inhibited by the treatment of 2 mmol/kg EDTA. The concentrations of chlorophyll a, chlorophyll b and total carotenoids in the leaves treated with 2 mmol/kg EDTA significantly decreased. Higher CA level and lower EDTA level could trigger the synthesis of ascorbic acid and higher level of EDTA could trigger the synthesis of glutathione. CA and EDTA could promote Pb accumulation of I. lactea var. chinensis and Pb concentration in the leaves and roots at 2 mmol/kg EDTA treatment increased significantly and reached to 160.44 and 936.08 μg/g DW, respectively, and 1.8 and 1.6 times higher than those of the control. The results indicated that I. lactea var. chinensis could be used to remediate Pb tailing and the role of EDTA in promoting Pb accumulation was better than CA did.

Influence of barley grain particle size and treatment with citric acid on digestibility, ruminal fermentation and microbial protein synthesis in Holstein calves.

PubMed

Kazemi-Bonchenari, M; Salem, A Z M; López, S

2017-08-01

Chemical and physical treatments of barley grain increase ruminally resistant starch and can improve the rumen fermentation pattern. The objective of the present study was to evaluate the effects of chemical (addition of citric acid, CA) and physical (grinding to two different particle sizes, PS) treatment of barley grain on performance, rumen fermentation, microbial protein yield in the rumen and selected blood metabolites in growing calves. In all, 28 male Holstein calves (172±5.1 kg initial BW) were used in a complete randomised design with a factorial arrangement of 2 barley grain particle sizes×2 levels of citric acid. The diets were as follows: (i) small PS (average 1200 µm) barley grain soaked in water (no CA addition); (ii) small PS barley grain soaked in a CA solution (adding 20 g CA/kg barley); (iii) large PS (average 2400 µm) barley grain soaked in water (no citric acid addition) and (iv) large PS barley grain soaked in a citric acid solution (adding 20 g CA/kg barley). Barley grain was then incorporated at 35% in a total mixed ration and fed to the calves for 11 weeks. Feeding small PS barley decreased feed intake (P=0.02) and average daily weight gain (P=0.01). The addition of CA to barley grain did not affect intake but increased weight gain (P0.05). However, the molar proportion of propionate was increased (P=0.03) when barley was more finely ground, and that of acetate was increased (P=0.04) when CA was added to barley grain. The ruminal concentration of ammonia nitrogen was increased (P<0.01) and microbial nitrogen synthesis in the rumen tended to decrease by adding CA to barley. Treating barley grain with citric acid increased fibre digestibility of total mixed rations, attenuated the decrease in ruminal pH, and improved weight gain and feed efficiency in male Holstein growing calves fed a high-cereal diet (550 g cereal grain/kg diet).

Amelioration of cadmium- and mercury-induced liver and kidney damage in rats by genetically engineered probiotic Escherichia coli Nissle 1917 producing pyrroloquinoline quinone with oral supplementation of citric acid.

PubMed

Raghuvanshi, Ruma; Chaudhari, Archana; Kumar, G Naresh

2016-01-01

Antioxidants, chelating agents, and probiotics are used to manage the toxic effects of cadmium (Cd) and mercury (Hg). The aim of this study was to investigate the combined effects of antioxidants, chelating agents, and probiotics against heavy metal toxicity. Genetically modified probiotic Escherichia coli Nissle 1917 (EcN-20) producing a potent water soluble antioxidant pyrroloquinoline quinone (PQQ) was supplemented with oral citric acid and compared with another genetically modified probiotic EcN-21 producing PQQ and citric acid against oxidative stress induced by Cd and Hg. Rats were independently given 100 ppm Cd and 80 ppm Hg in drinking water for 4 wk. EcN-20 was found to be more effective than EcN-2 (EcN strain with genomic integration of vgb and gfp genes) with orally given PQQ against oxidative stress induced by Cd and Hg. EcN-20 supplemented with oral citric acid was more effective against Cd and Hg toxicity compared with EcN-2+citric acid (oral), EcN-2+PQQ (oral), EcN-2+PQQ (oral)+citric acid (oral), EcN-20, and EcN-21. However, protection shown by EcN-21 was similar to EcN-20. The combination therapy involving probiotic EcN-20 producing PQQ with citric acid given orally was found to be a moderately effective strategy against toxicity induced by Cd and Hg, whereas the protective effect of EcN-21 was the same as EcN-20. Copyright © 2016 Elsevier Inc. All rights reserved.

Geochemical roots of autotrophic carbon fixation: hydrothermal experiments in the system citric acid, H 2O-(±FeS)-(±NiS)

NASA Astrophysics Data System (ADS)

Cody, G. D.; Boctor, N. Z.; Hazen, R. M.; Brandes, J. A.; Morowitz, Harold J.; Yoder, H. S.

2001-10-01

Recent theories have proposed that life arose from primitive hydrothermal environments employing chemical reactions analogous to the reductive citrate cycle (RCC) as the primary pathway for carbon fixation. This chemistry is presumed to have developed as a natural consequence of the intrinsic geochemistry of the young, prebiotic, Earth. There has been no experimental evidence, however, demonstrating that there exists a natural pathway into such a cycle. Toward this end, the results of hydrothermal experiments involving citric acid are used as a method of deducing such a pathway. Homocatalytic reactions observed in the citric acid-H2O experiments encompass many of the reactions found in modern metabolic systems, i.e., hydration-dehydration, retro-Aldol, decarboxylation, hydrogenation, and isomerization reactions. Three principal decomposition pathways operate to degrade citric acid under thermal and aquathermal conditions. It is concluded that the acid catalyzed βγ decarboxylation pathway, leading ultimately to propene and CO2, may provide the most promise for reaction network reversal under natural hydrothermal conditions. Increased pressure is shown to accelerate the principal decarboxylation reactions under strictly hydrothermal conditions. The effect of forcing the pH via the addition of NaOH reveals that the βγ decarboxylation pathway operates even up to intermediate pH levels. The potential for network reversal (the conversion of propene and CO2 up to a tricarboxylic acid) is demonstrated via the Koch (hydrocarboxylation) reaction promoted heterocatalytically with NiS in the presence of a source of CO. Specifically, an olefin (1-nonene) is converted to a monocarboxylic acid; methacrylic acid is converted to the dicarboxylic acid, methylsuccinic acid; and the dicarboxylic acid, itaconic acid, is converted into the tricarboxylic acid, hydroaconitic acid. A number of interesting sulfur-containing products are also formed that may provide for additional

Identification of a Classical Mutant in the Industrial Host Aspergillus niger by Systems Genetics: LaeA Is Required for Citric Acid Production and Regulates the Formation of Some Secondary Metabolites

PubMed Central

Niu, Jing; Arentshorst, Mark; Nair, P. Deepa S.; Dai, Ziyu; Baker, Scott E.; Frisvad, Jens C.; Nielsen, Kristian F.; Punt, Peter J.; Ram, Arthur F.J.

2015-01-01

The asexual filamentous fungus Aspergillus niger is an important industrial cell factory for citric acid production. In this study, we genetically characterized a UV-generated A. niger mutant that was originally isolated as a nonacidifying mutant, which is a desirable trait for industrial enzyme production. Physiological analysis showed that this mutant did not secrete large amounts of citric acid and oxalic acid, thus explaining the nonacidifying phenotype. As traditional complementation approaches to characterize the mutant genotype were unsuccessful, we used bulk segregant analysis in combination with high-throughput genome sequencing to identify the mutation responsible for the nonacidifying phenotype. Since A. niger has no sexual cycle, parasexual genetics was used to generate haploid segregants derived from diploids by loss of whole chromosomes. We found that the nonacidifying phenotype was caused by a point mutation in the laeA gene. LaeA encodes a putative methyltransferase-domain protein, which we show here to be required for citric acid production in an A. niger lab strain (N402) and in other citric acid production strains. The unexpected link between LaeA and citric acid production could provide new insights into the transcriptional control mechanisms related to citric acid production in A. niger. Interestingly, the secondary metabolite profile of a ΔlaeA strain differed from the wild-type strain, showing both decreased and increased metabolite levels, indicating that LaeA is also involved in regulating the production of secondary metabolites. Finally, we show that our systems genetics approach is a powerful tool to identify trait mutations. PMID:26566947

Identification of a Classical Mutant in the Industrial Host Aspergillus niger by Systems Genetics: LaeA Is Required for Citric Acid Production and Regulates the Formation of Some Secondary Metabolites.

PubMed

Niu, Jing; Arentshorst, Mark; Nair, P Deepa S; Dai, Ziyu; Baker, Scott E; Frisvad, Jens C; Nielsen, Kristian F; Punt, Peter J; Ram, Arthur F J

2015-11-13

The asexual filamentous fungus Aspergillus niger is an important industrial cell factory for citric acid production. In this study, we genetically characterized a UV-generated A. niger mutant that was originally isolated as a nonacidifying mutant, which is a desirable trait for industrial enzyme production. Physiological analysis showed that this mutant did not secrete large amounts of citric acid and oxalic acid, thus explaining the nonacidifying phenotype. As traditional complementation approaches to characterize the mutant genotype were unsuccessful, we used bulk segregant analysis in combination with high-throughput genome sequencing to identify the mutation responsible for the nonacidifying phenotype. Since A. niger has no sexual cycle, parasexual genetics was used to generate haploid segregants derived from diploids by loss of whole chromosomes. We found that the nonacidifying phenotype was caused by a point mutation in the laeA gene. LaeA encodes a putative methyltransferase-domain protein, which we show here to be required for citric acid production in an A. niger lab strain (N402) and in other citric acid production strains. The unexpected link between LaeA and citric acid production could provide new insights into the transcriptional control mechanisms related to citric acid production in A. niger. Interestingly, the secondary metabolite profile of a ΔlaeA strain differed from the wild-type strain, showing both decreased and increased metabolite levels, indicating that LaeA is also involved in regulating the production of secondary metabolites. Finally, we show that our systems genetics approach is a powerful tool to identify trait mutations. Copyright © 2016 Niu et al.

Identification of a classical mutant in the industrial host Aspergillus niger by systems genetics: LaeA is required for citric acid production and regulates the formation of some secondary metabolites

DOE PAGES

Niu, Jing; Arentshorst, Mark; Nair, P. Deepa S.; ...

2015-11-13

The asexual filamentous fungus Aspergillus niger is an important industrial cell factory for citric acid production. In this study, we genetically characterized a UV-generated A. niger mutant that was originally isolated as a nonacidifying mutant, which is a desirable trait for industrial enzyme production. Physiological analysis showed that this mutant did not secrete large amounts of citric acid and oxalic acid, thus explaining the nonacidifying phenotype. As traditional complementation approaches to characterize the mutant genotype were unsuccessful, we used bulk segregant analysis in combination with high-throughput genome sequencing to identify the mutation responsible for the nonacidifying phenotype. Since A. nigermore » has no sexual cycle, parasexual genetics was used to generate haploid segregants derived from diploids by loss of whole chromosomes. We found that the nonacidifying phenotype was caused by a point mutation in the laeA gene. LaeA encodes a putative methyltransferase-domain protein, which we show here to be required for citric acid production in an A. niger lab strain (N402) and in other citric acid production strains. The unexpected link between LaeA and citric acid production could provide new insights into the transcriptional control mechanisms related to citric acid production in A. niger. Interestingly, the secondary metabolite profile of a Δ laeA strain differed from the wild-type strain, showing both decreased and increased metabolite levels, indicating that LaeA is also involved in regulating the production of secondary metabolites. As a result, we show that our systems genetics approach is a powerful tool to identify trait mutations.« less

Identification of a classical mutant in the industrial host Aspergillus niger by systems genetics: LaeA is required for citric acid production and regulates the formation of some secondary metabolites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Niu, Jing; Arentshorst, Mark; Nair, P. Deepa S.

The asexual filamentous fungus Aspergillus niger is an important industrial cell factory for citric acid production. In this study, we genetically characterized a UV-generated A. niger mutant that was originally isolated as a nonacidifying mutant, which is a desirable trait for industrial enzyme production. Physiological analysis showed that this mutant did not secrete large amounts of citric acid and oxalic acid, thus explaining the nonacidifying phenotype. As traditional complementation approaches to characterize the mutant genotype were unsuccessful, we used bulk segregant analysis in combination with high-throughput genome sequencing to identify the mutation responsible for the nonacidifying phenotype. Since A. nigermore » has no sexual cycle, parasexual genetics was used to generate haploid segregants derived from diploids by loss of whole chromosomes. We found that the nonacidifying phenotype was caused by a point mutation in the laeA gene. LaeA encodes a putative methyltransferase-domain protein, which we show here to be required for citric acid production in an A. niger lab strain (N402) and in other citric acid production strains. The unexpected link between LaeA and citric acid production could provide new insights into the transcriptional control mechanisms related to citric acid production in A. niger. Interestingly, the secondary metabolite profile of a Δ laeA strain differed from the wild-type strain, showing both decreased and increased metabolite levels, indicating that LaeA is also involved in regulating the production of secondary metabolites. As a result, we show that our systems genetics approach is a powerful tool to identify trait mutations.« less

Effects of simulated acid rain, EDTA, or their combination, on migration and chemical fraction distribution of extraneous metals in Ferrosol.

PubMed

Wen, Fang; Hou, Hong; Yao, Na; Yan, Zengguang; Bai, Liping; Li, Fasheng

2013-01-01

A laboratory repacked soil-leaching column experiment was conducted to study the effects of simulated acid rain or EDTA by themselves or in combination, on migration and chemical speciation distribution of Pb and its alternative rare metals including Ag, Bi, In, Sb, and Sn. Experimental results demonstrate that leaching with simulated acid rain promoted the migration of Bi, In and Pb, and their migration reached down to 8 cm in the soil profile, no enhancement of Sb, Ag or Sn migration was observed. Addition of EDTA significantly enhanced the migration of all six metals, especially Bi, In and Pb. The migration of metals was in the order Pb>Bi>In>Sb>Sn>Ag. The individual and combined effects of acid rain and EDTA increased the environmental risk of metals, by increasing the soluble content of metals in soil solutions and the relative distribution of the exchangeable fraction. Leaching risks of Bi, In and Pb were higher than other three metals. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effect of EDTA and Tannic Acid on the Removal of Cd, Ni, Pb and Cu from Artificially Contaminated Soil by Althaea rosea Cavan.

PubMed

Cay, Seydahmet; Uyanik, Ahmet; Engin, Mehmet Soner; Kutbay, Hamdi Guray

2015-01-01

In this study an ornamental plant of Althaea rosea Cavan was investigated for its potential use in the removal of Cd, Ni, Pb and Cu from an artificially contaminated soil. Effect of two different chelating agents on the removal has also been studied by using EDTA (ethylenediaminetetracetic acid) and TA (tannic acid). Both EDTA and TA have led to higher heavy metal concentration in shoots and leaves compared to control plants. However EDTA is generally known as an effective agent in metal solubilisation of soil, in this study, TA was found more effective to induce metal accumulation in Althaea rosea Cavan under the studied conditions. In addition to this, EDTA is toxic to some species and restraining the growth of the plants. The higher BCF (Bio Concentration Factor) and TF (Translocation Factor) values obtained from stems and leaves by the effects of the chemical enhancers (EDTA and TA) show that Althaea rosea Cavan is a hyper accumulator for the studied metals and may be cultivated to clean the contaminated soils.

Data of thermal degradation and dynamic mechanical properties of starch–glycerol based films with citric acid as crosslinking agent

PubMed Central

González Seligra, Paula; Medina Jaramillo, Carolina; Famá, Lucía; Goyanes, Silvia

2016-01-01

Interest in biodegradable edible films as packaging or coating has increased because their beneficial effects on foods. In particular, food products are highly dependents on thermal stability, integrity and transition process temperatures of the packaging. The present work describes a complete data of the thermal degradation and dynamic mechanical properties of starch–glycerol based films with citric acid (CA) as crosslinking agent described in the article titled: “Biodegradable and non-retrogradable eco-films based on starch–glycerol with citric acid as crosslinking agent” González Seligra et al. (2016) [1]. Data describes thermogravimetric and dynamical mechanical experiences and provides the figures of weight loss and loss tangent of the films as a function of the temperature. PMID:27158645

Photostabilization of ascorbic acid with citric acid, tartaric acid and boric acid in cream formulations.

PubMed

Ahmad, I; Ali Sheraz, M; Ahmed, S; Shad, Z; Vaid, F H M

2012-06-01

This study involves the evaluation of the effect of certain stabilizers, that is, citric acid (CT), tartaric acid (TA) and boric acid (BA) on the degradation of ascorbic acid (AH(2) ) in oil-in-water cream formulations exposed to the UV light and stored in the dark. The apparent first-order rate constants (0.34-0.95 × 10(-3) min(-1) in light, 0.38-1.24 × 10(-2) day(-1) in dark) for the degradation reactions in the presence of the stabilizers have been determined. These rate constants have been used to derive the second-order rate constants (0.26-1.45 × 10(-2) M(-1) min(-1) in light, 3.75-8.50 × 10(-3) M(-1) day(-1) in dark) for the interaction of AH(2) and the individual stabilizers. These stabilizers are effective in causing the inhibition of the rate of degradation of AH(2) both in the light and in the dark. The inhibitory effect of the stabilizers is in the order of CT > TA > BA. The rate of degradation of AH(2) in the presence of these stabilizers in the light is about 120 times higher than that in the dark. This could be explained on the basis of the deactivation of AH(2) -excited triplet state by CT and TA and by the inhibition of AH(2) degradation through complex formation with BA. AH(2) leads to the formation of dehydroascorbic acid (A) by chemical and photooxidation in cream formulations. © 2012 The Authors. ICS © 2012 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Enzymes in Glycolysis and the Citric Acid Cycle in the Yeast and Mycelial Forms of Paracoccidioides brasiliensis

PubMed Central

Kanetsuna, Fuminori; Carbonell, Luis M.

1966-01-01

Kanetsuna, Fuminori (Instituto Venezolano de Investigaciones Cientificas, Caracas, Venezuela), and Luis M. Carbonell. Enzymes in glycolysis and the citric acid cycle in the yeast and mycelial forms of Paracoccidioides brasiliensis. J. Bacteriol. 92:1315–1320. 1966.—Enzymatic activities in glycolysis, the hexose monophosphate shunt, and the citric acid cycle in cell-free extracts of the yeast and mycelial forms of Paracoccidioides brasiliensis were examined comparatively. Both forms have the enzymes of these pathways. Activities of glucose-6-phosphate dehydrogenase and malic dehydrogenase of the mycelial form were higher than those of the yeast form. Another 15 enzymatic activities of the mycelial form were lower than those of the yeast form. The activity of glyceraldehyde-3-phosphate dehydrogenase showed the most marked difference between the two forms, its activity in the mycelial form being about 20% of that in the yeast form. PMID:5924267

C-Myc Induced Compensated Cardiac Hypertrophy Increases Free Fatty Acid Utilization for the Citric Acid Cycle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Olson, Aaron; Ledee, Dolena; Iwamoto, Kate

The protooncogene C-Myc (Myc) regulates cardiac hypertrophy. Myc promotes compensated cardiac function, suggesting that the operative mechanisms differ from those leading to heart failure. Myc regulation of substrate metabolism is a reasonable target, as Myc alters metabolism in other tissues. We hypothesize that Myc-induced shifts in substrate utilization signal and promote compensated hypertrophy. We used cardiac specific Myc-inducible C57/BL6 male mice between 4-6 months old that develop hypertrophy with tamoxifen (tam). Isolated working hearts and 13Carbon (13C )-NMR were used to measure function and fractional contributions (Fc) to the citric acid cycle by using perfusate containing 13C-labeled free fatty acids,more » acetoacetate, lactate, unlabeled glucose and insulin. Studies were performed at pre-hypertrophy (3-days tam, 3dMyc), established hypertrophy (7-days tam, 7dMyc) or vehicle control (cont). Non-transgenic siblings (NTG) received 7-days tam or vehicle to assess drug effect. Hypertrophy was confirmed by echocardiograms and heart weights. Western blots were performed on key metabolic enzymes. Hypertrophy occurred in 7dMyc only. Cardiac function did not differ between groups. Tam alone did not affect substrate contribution in NTG. Substrate utilization was not significantly altered in 3dMyc versus cont. The free fatty acid FC was significantly greater in 7dMyc vs cont with decreased unlabeled Fc, which is predominately exogenous glucose. Free fatty acid flux to the citric acid cycle increased while lactate flux was diminished in 7dMyc compared to cont. Total protein levels of a panel of key metabolic enzymes were unchanged; however total protein O-GlcNAcylation was increased in 7dMyc. Substrate utilization changes did not precede hypertrophy; therefore they are not the primary signal for cardiac growth in this model. Free fatty acid utilization and oxidation increase at established hypertrophy. Understanding the mechanisms whereby this change

Expression of the H+-ATPase AHA10 proton pump is associated with citric acid accumulation in lemon juice sac cells.

PubMed

Aprile, Alessio; Federici, Claire; Close, Timothy J; De Bellis, Luigi; Cattivelli, Luigi; Roose, Mikeal L

2011-12-01

The sour taste of lemons (Citrus limon (L.) Burm.) is determined by the amount of citric acid in vacuoles of juice sac cells. Faris is a "sweet" lemon variety since it accumulates low levels of citric acid. The University of California Riverside Citrus Variety Collection includes a Faris tree that produces sweet (Faris non-acid; FNA) and sour fruit (Faris acid; FA) on different branches; it is apparently a graft chimera with layer L1 derived from Millsweet limetta and layer L2 from a standard lemon. The transcription profiles of Faris sweet lemon were compared with Faris acid lemon and Frost Lisbon (L), which is a standard sour lemon genetically indistinguishable from Faris in prior work with SSR markers. Analysis of microarray data revealed that the transcriptomes of the two sour lemon genotypes were nearly identical. In contrast, the transcriptome of Faris sweet lemon was very different from those of both sour lemons. Among about 1,000 FNA-specific, presumably pH-related genes, the homolog of Arabidopsis H(+)-ATPase proton pump AHA10 was not expressed in FNA, but highly expressed in FA and L. Since Arabidopsis AHA10 is involved in biosynthesis and acidification of vacuoles, the lack of expression of the AHA10 citrus homolog represents a very conspicuous molecular feature of the FNA sweet phenotype. In addition, high expression of several 2-oxoglutarate degradation-related genes in FNA suggests activation of the GABA shunt and degradation of valine and tyrosine as components of the mechanism that reduces the level of citric acid in sweet lemon.

Influences of AMY1 gene copy number and protein expression on salivary alpha-amylase activity before and after citric acid stimulation in splenic asthenia children.

PubMed

Yang, Zemin; Lin, Jing; Chen, Longhui; Zhang, Min; Yang, Xiaorong; Chen, Weiwen

2015-06-01

To compare the correlations between salivary alpha-amylase (sAA) activity and amylase, alpha 1 (salivary) gene (AMYl) copy number or its gene expression between splenic asthenia and healthy children, and investigate the reasons of attenuated sAA activity ratio before and after citric acid stimulation in splenic asthenia children. Saliva samples from 20 splenic asthenia children and 29 healthy children were collected before and after citric acid stimulation. AMYl copy number, sAA activity, and total sAA and glycosylated sAA contents were determined, and their correlations were analyzed. Although splenic asthenia and healthy children had no differences in AMY1 copy number, splenic asthenia children had positive correlations between AMY1 copy number and sAA activity before or after citric acid stimulation. Splenic asthenia children had a higher sAA glycosylated proportion ratio and glycosylated sAA content ratio, while their total sAA content ratio and sAA activity ratio were lower compared with healthy children. The glycosylated sAA content ratio was higher than the total sAA content ratio in both groups. Splenic asthenia and healthy children had positive correlations between total sAA or glycosylated sAA content and sAA activity. However, the role played by glycosylated sAA content in sAA activity in healthy children increased after citric acid stimulation, while it decreased in splenic asthenia children. Genetic factors like AMY1 copy number variations, and more importantly, sAA glycosylation abnormalities leading to attenuated sAA activity after citric acid stimulation, which were the main reasons of the attenuated sAA activity ratio in splenic asthenia children compared with healthy children.

EDTA aggregates induce SYPRO orange-based fluorescence in thermal shift assay

PubMed Central

Kroeger, Tobias; Frieg, Benedikt; Zhang, Tao; Hansen, Finn K.; Marmann, Andreas; Proksch, Peter; Nagel-Steger, Luitgard; Groth, Georg; Smits, Sander H. J.

2017-01-01

Ethylenediaminetetraacetic acid (EDTA) is widely used in the life sciences as chelating ligand of metal ions. However, formation of supramolecular EDTA aggregates at pH > 8 has been reported, which may lead to artifactual assay results. When applied as a buffer component at pH ≈ 10 in differential scanning fluorimetry (TSA) using SYPRO Orange as fluorescent dye, we observed a sharp change in fluorescence intensity about 20°C lower than expected for the investigated protein. We hypothesized that this change results from SYPRO Orange/EDTA interactions. TSA experiments in the presence of SYPRO Orange using solutions that contain EDTA-Na+ but no protein were performed. The TSA experiments provide evidence that suggests that at pH > 9, EDTA4- interacts with SYPRO Orange in a temperature-dependent manner, leading to a fluorescence signal yielding a “denaturation temperature” of ~68°C. Titrating Ca2+ to SYPRO Orange and EDTA solutions quenched fluorescence. Ethylene glycol tetraacetic acid (EGTA) behaved similarly to EDTA. Analytical ultracentrifugation corroborated the formation of EDTA aggregates. Molecular dynamics simulations of free diffusion of EDTA-Na+ and SYPRO Orange of in total 27 μs suggested the first structural model of EDTA aggregates in which U-shaped EDTA4- arrange in an inverse bilayer-like manner, exposing ethylene moieties to the solvent, with which SYPRO Orange interacts. We conclude that EDTA aggregates induce a SYPRO Orange-based fluorescence in TSA. These results make it relevant to ascertain that future TSA results are not influenced by interference between EDTA, or EDTA-related molecules, and the fluorescent dye. PMID:28472107

Reactivity of OHrad and e-aq from electron beam irradiation of aqueous solutions of EDTA and aminopolycarboxylic acids

NASA Astrophysics Data System (ADS)

Vel Leitner, N. Karpel; Guilbault, I.; Legube, B.

2003-05-01

Electron beam irradiation of aqueous solutions of EDTA, EDDA NN‧, NTA, IDA and Cu-EDTA was performed in the presence of scavengers for the hydroxyl radicals (methanol) or for the solvated electrons (hydrogen peroxide). Experiments showed that for each molecule, the G-value decreases as the radiation dose increases from 1 to 25 kGy, and for EDTA, when the initial concentration decreases from 10 to 0.1 mmol l-1. At pH 8 and for 5 kGy, the G-values of NTA, IDA, EDTA and EDDA NN‧ removal ascribed to OHrad radicals are, respectively, 0.06, 0.06, 0.15 and 0.20 μmol J-1, whereas for the solvated electrons the G-values were, respectively, 0.01, 0.01, 0.06 and 0.04 μmol J-1. The rate constants of hydroxyl radicals and solvated electrons were determined by comparison with one competitor. For each active species (hydroxyl radical or solvated electron), the reactivity is connected to the number of nitrogen atoms and acetate groups. The rate constants of OHrad radicals are above 1010 and 8.6×109 l mol-1 s-1 for EDDA NN‧ and EDTA, respectively, 2.1×109 l mol-1 s-1 for IDA and 6.1×108 l mol-1 s-1 for NTA. The reactivity of solvated electrons is smaller and the rate constants are in the range 1.9×106-3.7×106 l mol-1 s-1 for NTA, IDA and EDDA NN‧ and equal 1.4×107 l mol-1 s-1 for EDTA. The reactivity of the complex Cu-EDTA towards OHrad does not differ to a large extent from EDTA whereas with e-aq the reactivity of Cu-EDTA is better than EDTA since ke-/Cu-EDTA reaches 2.2×109 l mol-1 s-1. It follows that when both active entities (OHrad and e-aq) are involved in the electron beam irradiation process, the removal of free aminopolycarboxylic acids is mainly due to OHrad radicals. However, the complex Cu-EDTA is concerned by both e-aq and OHrad radicals.

Formation of uniform carrot-like Cu31S16-CuInS2 heteronanostructures assisted by citric acid at the oil/aqueous interface.

PubMed

Li, Yongjie; Tang, Aiwei; Liu, Zhenyang; Peng, Lan; Yuan, Yi; Shi, Xifeng; Yang, Chunhe; Teng, Feng

2018-01-07

A simple two-phase strategy was developed to prepare Cu 31 S 16 -CuInS 2 heterostructures (HNS) at the oil/aqueous interface, in which the In(OH) 3 phase was often obtained in the products due to the reaction between indium ions and hydroxyl ions in the aqueous phase. To prevent the formation of the In(OH) 3 phase, citric acid was incorporated into the aqueous phase to assist in the synthesis of uniform carrot-like Cu 31 S 16 -CuInS 2 semiconductor HNS at the oil/aqueous interface for the first time. By manipulating the dosage of citric acid and Cu/In precursor ratios, the morphology of the Cu 31 S 16 -CuInS 2 HNS could be tailored from mushroom to carrot-like, and the presence of citric acid played a critical role in the synthesis of high-quality Cu 31 S 16 -CuInS 2 HNS, which inhibited the formation of the In(OH) 3 phase due to the formation of the indium(iii)-citric acid complex. The formation mechanism was studied by monitoring the morphology and phase evolution of the Cu 31 S 16 -CuInS 2 HNS with reaction time, which revealed that the Cu 31 S 16 seeds were first formed and then the cation-exchange reaction directed the subsequent anisotropic growth of the Cu 31 S 16 -CuInS 2 HNS.

Resin-dentin bonds to EDTA-treated vs. acid-etched dentin using ethanol wet-bonding. Part II: Effects of mechanical cycling load on microtensile bond strengths.

PubMed

Sauro, Salvatore; Toledano, Manuel; Aguilera, Fatima Sánchez; Mannocci, Francesco; Pashley, David H; Tay, Franklin R; Watson, Timothy F; Osorio, Raquel

2011-06-01

To compare microtensile bond strengths (MTBS) subsequent to load cycling of resin bonded acid-etched or EDTA-treated dentin using a modified ethanol wet-bonding technique. Flat dentin surfaces were obtained from extracted human molars and conditioned using 37% H(3)PO(4) (PA) (15s) or 0.1M EDTA (60s). Five experimental adhesives and one commercial bonding agent were applied to the dentin and light-cured. Solvated experimental resins (50% ethanol/50% comonomers) were used as primers and their respective neat resins were used as the adhesives. The resin-bonded teeth were stored in distilled water (24h) or submitted to 5000 loading cycles of 90N. The bonded teeth were then sectioned in beams for MTBS. Modes of failure were examined by scanning electron microscopy. The most hydrophobic resin 1 gave the lowest bond strength values to both acid and EDTA-treated dentin. The hydrophobic resin 2 applied to EDTA-treated dentin showed lower bond strengths after cycling load but this did not occur when it was bonded to PA-etched dentin. Resins 3 and 4, which contained hydrophilic monomers, gave higher bond strengths to both EDTA-treated or acid-etched dentin and showed no significant difference after load cycling. The most hydrophilic resin 5 showed no significant difference in bond strengths after cycling loading when bonded to EDTA or phosphoric acid treated dentin but exhibited low bond strengths. The presence of different functional monomers influences the MTBS of the adhesive systems when submitted to cyclic loads. Adhesives containing hydrophilic comonomers are not affected by cycling load challenge especially when applied on EDTA-treated dentin followed by ethanol wet bonding. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Remediation and desorption kinetics of pyrene from kaolinite co-contaminated with heavy metals at various organic matter contents

NASA Astrophysics Data System (ADS)

Saeedi, Mohsen; Li, Loretta Y.; Grace, John R.

2017-04-01

Soils co-contaminated with polycyclic aromatic hydrocarbons (PAHs) and heavy metals are challenging for remediation. In the present study desorption of pyrene in kaolinite, co-contaminated by Ni, Pb and Zn, was examined by combinations of surfactants and chelating agents such as Triton X-100, Tween 80, Ethylene diamine tetra acetic acid (EDTA) and citric acid. Results showed that a combination of Triton X-100 (7.5 % w/w) + EDTA (0.01 M) and Tween 80 (7.5 % w/w) + EDTA (0.01 M) were effective in simultaneously desorbing both types of contaminants. Batch desorption tests were conducted using single and combined enhancing agents containing Triton X-100 and Tween 80 as non-ionic surfactants, EDTA as a chelating agent, and citric acid as an organic acid. The solution with the highest removal efficiency was the combined solution containing Triton X-100 (7.5 % w/w) + EDTA (0.01M). Triton X-100 (7.5% w/w) + EDTA (0.01M) led to removal efficiencies of 88% for pyrene in base kaolinite. Batch desorption kinetic experiments were performed using Triton X-100 (7.5% w/w) + EDTA (0.01M). During the first 24 h, desorption was rapid. Organic matter content in the kaolinite led to a reduction in the desorption rate of the contaminants. The desorption kinetic data were well fitted by a pseudo-second-order kinetic model.

Multifunctional adhesive polymers: Preactivated thiolated chitosan-EDTA conjugates.

PubMed

Netsomboon, Kesinee; Suchaoin, Wongsakorn; Laffleur, Flavia; Prüfert, Felix; Bernkop-Schnürch, Andreas

2017-02-01

The aim of this study was to synthesis preactivated thiolated chitosan-EDTA (Ch-EDTA-cys-2MNA) conjugates exhibiting in particular high mucoadhesive, cohesive and chelating properties. Thiol groups were coupled with chitosan by carbodiimide reaction and further preactivated by attachment with 2-mercaptonicotinic acid (2MNA) via disulfide bond formation. Determinations of primary amino and sulfhydryl groups were performed by TNBS and Ellman's tests, respectively. Cytotoxicity was screened by resazurin assay in Caco-2 cells. Mucoadhesive properties and bivalent cation binding capacity with Mg 2+ and Ca 2+ in comparison to chitosan-EDTA (Ch-EDTA) and thiolated Ch-EDTA (Ch-EDTA-cys) were evaluated. Determination of 2MNA and total sulfhydryl groups indicated that 80% of thiol groups were preactivated. The results from cytotoxicity studies demonstrated that Ch-EDTA-cys and Ch-EDTA-cys-2MNA were not toxic to the cells at the polymer test concentration of 0.25% (w/v) while cell viability decreased by increasing the concentration of Ch-EDTA. Although EDTA molecule was modified by thiolation and preactivation, approximately 50% of chelating properties of the conjugates were maintained compared to Ch-EDTA. Ch-EDTA-cys-2MNA adhered on freshly excised porcine intestinal mucosa up to 6h while Ch-EDTA adhered for just 1h. According to the combination of mucoadhesive and chelating properties of the conjugates synthesized in this study, Ch-EDTA-cys-2MNA might be useful for various mucosal drug delivery systems. Copyright © 2016 Elsevier B.V. All rights reserved.

Approaches to improve the stability of the antiviral agent UC781 in aqueous solutions.

PubMed

Damian, Festo; Fabian, Judit; Friend, David R; Kiser, Patrick F

2010-08-30

In this work, we evaluated the chemical stability profiles of UC781 based solutions to identify excipients that stabilize the microbicidal agent UC781. When different antioxidants were added to UC781 in sulfobutylether-beta-cyclodextrin (SBE-beta-CD) solutions and subjected to a 50 degrees C stability study, it was observed that EDTA was a better stabilizing agent than sodium metabisulfite, glutathione or ascorbic acid. Some antioxidants accelerated the degradation of UC781, suggesting metal-catalyzed degradation of UC781. Furthermore, we observed substantial degradation of UC781 when stored in 1% Tween 80 and 1% DMSO solutions alone or in those with 10mM EDTA. On the other hand, improved stability of UC781 in the presence of 100 and 200mM of EDTA was observed in these solutions. The addition of both EDTA and citric acid in the stock solutions resulted in recovery of more than 60% of UC781 after 12 weeks. Generally, 10% SBE-beta-CD in the presence of EDTA and citric acid stabilized UC781 solutions: the amount of UC781 recovered approaching 95% after 12 weeks of storage at 40 degrees C. We also showed that the desulfuration reaction of the UC781 thioamide involves oxygen by running solution stability studies in deoxygenated media. Improved stability of UC781 in the present study indicates that the incorporation of EDTA, citric acid and SBE-beta-CD and the removal of oxygen in formulations of this drug will aid in increasing the stability of UC781 where solutions of the drug are required. Published by Elsevier B.V.

Functionalization of yogurts with Agaricus bisporus extracts encapsulated in spray-dried maltodextrin crosslinked with citric acid.

PubMed

Francisco, Cristhian R L; Heleno, Sandrina A; Fernandes, Isabel P M; Barreira, João C M; Calhelha, Ricardo C; Barros, Lillian; Gonçalves, Odinei Hess; Ferreira, Isabel C F R; Barreiro, Maria Filomena

2018-04-15

Mushroom extracts contain bioactive compounds potentially useful to functionalize foodstuffs. Herein, alcoholic extracts of Agaricus bisporus were studied for their bioactivity and viability as functional ingredients in a food product with high water content (yogurt). Extracts were microencapsulated (to improve their stability and hydrophilicity) by spray-drying, using maltodextrin crosslinked with citric acid as encapsulating material. The effect of thermal treatment (after atomization) on crosslinking and bioactivity of microspheres was tested. The incorporation of free and thermally untreated forms resulted in yogurts with higher initial antioxidant activity (EC 50 values: 214 and 272 mg.mL -1 ) that decreased after 7 days (EC 50 values: 248 and 314 mg.mL -1 ). Contrarily, thermally treated microencapsulated extracts showed higher antioxidant activity after the same period (EC 50 values, 0 days: 106 mg.mL -1 ; 7 days: 48.7 mg.mL -1 ), in result of an effective protection provided by microencapsulation with crosslinked maltodextrin and citric acid. Functionalized yogurts showed an overall maintenance of nutritional properties. Copyright © 2017 Elsevier Ltd. All rights reserved.

Inert Reassessment Document for Ethylenediaminetetracetric acid (EDTA)

EPA Pesticide Factsheets

EDTA is a chelating agent. Its ability to bind heavy metal ions can be used to sequester these trace metals. However, trace amounts of various metals are necessary for the proper functioning of the body.

Growth and characterization of EDTA assisted CBD-CdS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumarage, W. G. C.; Wijesundera, R. P.; Seneviratne, V. A.

2017-10-01

Chemical bath deposition of CdS (CBD-CdS) thin films with the assistance of a cationic surfactant, ethylenediamine tetraacetic acid (EDTA), is reported in this work. Also the EDTA treated CdS thin films are compared with that of conventional CBD-CdS. Fabricated thin, compact, uniform and adherent EDTA treated CdS films show enhanced effective surface area and roughness compared to conventional CBD-CdS. The grazing incidence x-ray diffraction analysis shows all the fabricated CdS films are hexagonally crystallized. EDTA-treated CdS films show excellent photo activity compared to conventional CBDCdS. The flat band potential (Vfb) value was found to be tunable with EDTA concentration.

Effect of EDTA and phosphoric Acid pretreatment on the bonding effectiveness of self-etch adhesives to ground enamel.

PubMed

Ibrahim, Ihab M; Elkassas, Dina W; Yousry, Mai M

2010-10-01

This in vitro study determined the effect of enamel pretreatment with phosphoric acid and ethylenediaminetetraacetic acid (EDTA) on the bond strength of strong, intermediary strong, and mild self-etching adhesive systems. Ninety sound human premolars were used. Resin composite cylinders were bonded to flat ground enamel surfaces using three self-etching adhesive systems: strong Adper Prompt L-Pop (pH=0.9-1.0), intermediary strong AdheSE (pH=1.6-1.7), and mild Frog (pH=2). Adhesive systems were applied either according to manufacturer instructions (control) or after pretreatment with either phosphoric acid or EDTA (n=10). After 24 hours, shear bond strength was tested using a universal testing machine at a cross-head speed of 0.5 mm/minute. Ultra-morphological characterization of the surface topography and resin/enamel interfaces as well as representative fractured enamel specimens were examined using scanning electron microscopy (SEM). Neither surface pretreatment statistically increased the mean shear bond strength values of either the strong or the intermediary strong self-etching adhesive systems. However, phosphoric acid pretreatment significantly increased the mean shear bond strength values of the mild self-etching adhesive system. SEM examination of enamel surface topography showed that phosphoric acid pretreatment deepened the same etching pattern of the strong and intermediary strong adhesive systems but converted the irregular etching pattern of the mild self-etching adhesive system to a regular etching pattern. SEM examination of the resin/enamel interface revealed that deepening of the etching pattern was consistent with increase in the length of resin tags. EDTA pretreatment had a negligible effect on ultra-morphological features. Use of phosphoric acid pretreatment can be beneficial with mild self-etching adhesive systems for bonding to enamel.

Effect of EDTA and Phosphoric Acid Pretreatment on the Bonding Effectiveness of Self-Etch Adhesives to Ground Enamel

PubMed Central

Ibrahim, Ihab M.; Elkassas, Dina W.; Yousry, Mai M.

2010-01-01

Objectives: This in vitro study determined the effect of enamel pretreatment with phosphoric acid and ethylenediaminetetraacetic acid (EDTA) on the bond strength of strong, intermediary strong, and mild self-etching adhesive systems. Methods: Ninety sound human premolars were used. Resin composite cylinders were bonded to flat ground enamel surfaces using three self-etching adhesive systems: strong Adper Prompt L-Pop (pH=0.9–1.0), intermediary strong AdheSE (pH=1.6–1.7), and mild Frog (pH=2). Adhesive systems were applied either according to manufacturer instructions (control) or after pretreatment with either phosphoric acid or EDTA (n=10). After 24 hours, shear bond strength was tested using a universal testing machine at a cross-head speed of 0.5 mm/minute. Ultra-morphological characterization of the surface topography and resin/enamel interfaces as well as representative fractured enamel specimens were examined using scanning electron microscopy (SEM). Results: Neither surface pretreatment statistically increased the mean shear bond strength values of either the strong or the intermediary strong self-etching adhesive systems. However, phosphoric acid pretreatment significantly increased the mean shear bond strength values of the mild self-etching adhesive system. SEM examination of enamel surface topography showed that phosphoric acid pretreatment deepened the same etching pattern of the strong and intermediary strong adhesive systems but converted the irregular etching pattern of the mild self-etching adhesive system to a regular etching pattern. SEM examination of the resin/enamel interface revealed that deepening of the etching pattern was consistent with increase in the length of resin tags. EDTA pretreatment had a negligible effect on ultra-morphological features. Conclusions: Use of phosphoric acid pretreatment can be beneficial with mild self-etching adhesive systems for bonding to enamel. PMID:20922162

The effect of time in the exposure of theobromine gel to enamel and surface hardness after demineralization with 1% citric acid

NASA Astrophysics Data System (ADS)

Irawan, M. I. P.; Noerdin, A.; Eriwati, Y. K.

2017-08-01

Theobromine is one of the alkaloid compounds that can be found in cacao (Theobroma cacao). It is said that theobromine can prevent enamel demineralization. The aim of this research was to evaluate the effect of different exposure times to 200 mg/L theobromine gel on enamel microhardness after demineralization in 1% citric acid. Twenty-eight specimens of human premolar teeth were divided into four groups and were immersed in 1% citric acid (pH 4) for 2.5 minutes. Then 200 mg/L theobromine gel was exposed to the specimens for 16 minutes (n = 7), 48 minutes (n = 7), and 96 minutes (n = 7). Enamel microhardness (KHN) values were tested using the Knoop Microhardness Tester (Shimadzu, Japan) using a 50-gram load for 5 seconds. A statistical test was performed using the Friedman test, Wilcoxon test, Kruskal-Wallis test, and Mann-Whitney test. The results showed a significant decrease, of microhardness values after demineralization with 1% citric acid. There was also a significant increase in hardness (p<0.05) after exposure of the demineralized specimens to theobromine gel for 16 minutes (32.3%), 48 minutes (39.8%), and 96 minutes (43.7%). It can be concluded that exposure to 200 mg/L theobromine gel for 16, 48, and 96 minutes increased enamel microhardness.

Effect of cellulose nanocrystals (CNC) addition and citric acid as co-plasticizer on physical properties of sago starch biocomposite

NASA Astrophysics Data System (ADS)

Nasution, Halimatuddahliana; Afandy, Yayang; Al-fath, M. Thoriq

2018-04-01

Cellulose has potential applications in new high-performance materials with low environmental impact. Rattan biomass is a fiber waste from processing industry of rattan which contains 37,6% cellulose. The high cellulose contents of rattan biomass make it a source of cellulose nanocrystals as a filler in biocomposite. Isolation of alpha cellulose from biomass rattan was prepared by using three stages: delignification, alkalization, and bleaching. It was delignificated with 3,5% HNO3 and NaNO2, precipitated with 17,5% NaOH, bleaching process with 10% H2O2. Nanocrystals obtained through the hydrolysis of alpha cellulose using 45% H2SO4 and followed by mechanical processes of ultrasonication, centrifugation, and filtration with a dialysis membrane. Sago starch biocomposites were prepared using a solution casting method, which includes 1-4 wt % cellulose nanocrystals rattan biomass as fillers, 10-40 wt% citric acid as co-plasticizer and 30 wt% glycerol as plasticizer. The results of TEM and FTIR characteristic of cellulose nanocrystals show spherical like shape FTIR and chemical composition analysis demonstrated that lignin and hemicellulose structures were successfully removed. Biocomposite characteristic consists of density and water absorption. The results showed the highest density values were 0,266 gram/cm3 obtained at an additional of 3% cellulose nanocrystals rattan biomass and 30% citric acid. The lowest water absorption was 7,893% obtained at an additional of 4% cellulose nanocrystals rattan biomass and 10% citric acid.

77 FR 74171 - Citric Acid and Certain Citrate Salts From the People's Republic of China: Final Results of...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-13

... citric acid sodium salt, and the monohydrate and monopotassium forms of potassium citrate.\\5\\ Sodium... (``HTSUS''), respectively. Potassium citrate and crude calcium citrate are classifiable under 2918.15.5000... potassium citrate are classifiable under 3824.90.9290 of the HTSUS. Although the HTSUS subheadings are...

78 FR 34642 - Citric Acid and Certain Citrate Salts From the People's Republic of China: Preliminary Results of...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-10

... monopotassium forms of potassium citrate.\\1\\ Sodium citrate also includes both trisodium citrate and monosodium... Tariff Schedule of the United States (``HTSUS''), respectively. Potassium citrate and crude calcium... include citric acid, sodium citrate, and potassium citrate are classifiable under 3824.90.9290 of the...

Validation of the ERS standard citric acid cough challenge in healthy adult volunteers

PubMed Central

2010-01-01

Protocols measuring cough sensitivity can vary in terms of nebuliser, tussive agent, single and dose response. A definitive method for measuring cough sensitivity needs to be established. The ERS guidelines recommend the KoKo DigiDoser (KD) delivery system. Study aim, was to compare the reproducibility of this citric acid (CA) cough challenge and previously established Mefar dosimeter (MD) protocol. 39 (female 26) volunteers mean age (40.4 yrs) were randomised to either KD or MD. Intra-day and inter-day reproducibility was compared. We calculated the concentration of citric acid evoking 2 coughs (C2). The geometric mean C2 (95%CI) was similar for both KD and MD, of 263 (200,339) mM and 209 (151,288) mM respectively. The mean KD C2 was not significantly different. (F = 0.807, p = 0.93) from baseline over 1, 2, and 4 hrs however, the MD demonstrated significant variability (F = 7.85, P < 0.001) Measuring mean log C2 at baseline and at 2 weeks, the KD demonstrated a stronger intraclass correlation of log C2 at baseline with 2 week log C2, ICC = 0.70 than was shown with the Mefar, ICC = 0.41 Administering CA from KD offers a reproducible cough challenge in healthy volunteers. The results correlate well with the MD challenge but offer greater intra-day and inter-day reproducibility. Trial Registration Current controlled trials ISRCTN98385033 PMID:20698995

EDTA assisted synthesis of hydroxyapatite nanoparticles for electrochemical sensing of uric acid.

PubMed

Kanchana, P; Sekar, C

2014-09-01

Hydroxyapatite nanoparticles have been synthesized using EDTA as organic modifier by a simple microwave irradiation method and its application for the selective determination of uric acid (UA) has been demonstrated. Electrochemical behavior of uric acid at HA nanoparticle modified glassy carbon electrode (E-HA/GCE) has been investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), linear sweep voltammetry (LSV) and amperometry. The E-HA modified electrode exhibits efficient electrochemical activity towards uric acid sensing without requiring enzyme or electron mediator. Amperometry studies revealed that the fabricated electrode has excellent sensitivity for uric acid with the lowest detection limit of 142 nM over a wide concentration range from 1 × 10(-7) to 3 × 10(-5)M. Moreover, the studied E-HA modified GC electrode exhibits a good reproducibility and long-term stability and an admirable selectivity towards the determination of UA even in the presence of potential interferents. The analytical performance of this sensor was evaluated for the detection of uric acid in human urine and blood serum samples. Copyright © 2014. Published by Elsevier B.V.

The effect of pH on citric acid cough challenge: A randomised control trial in chronic cough and healthy volunteers.

PubMed

Rai, Z L; Fowles, H E; Wright, C; Howard, Joseph; Morice, A H

2018-03-06

Citric acid has been used for over six decades to induce cough; however the mechanism of its pro-tussive effect is still not fully understood. We assessed the response to inhalation of citric acid at varying levels of acidity to determine if the pH of the solution plays a role in the induction of cough. Data was collected from both healthy volunteers and patients with chronic cough. 20 chronic cough patients and 20 healthy volunteers were recruited and underwent three cough challenges on separate days. Each visit involved 5 repeated one second inhalations of 300 mM citric acid solution. The concentration of the citrate cation remained constant, but the pH of the solution altered by the addition of sodium bicarbonate to 3, 5 and 6, representing the pK a values of the individual acid moieties. The total number of coughs elicited was recorded for each inhalation. Two subjects withdrew and were not included in the analysis. Participants were gender matched, each group consisting of 12 females. 74% of chronic coughers coughed at pH 3 (mean coughs 16), 89% coughed at pH 5 (18) and 63% coughed at pH 6 (7). In healthy volunteers, 60% of subjects coughed at pH 3 (9), 30% of subjects coughed at pH 5 (3), and 10% of subjects coughed at pH 6 (0). Thus chronic cough patients coughed more than healthy volunteers and did not exhibit a clear pH concentration response. There was also a greater variability in their response to individual challenges. Copyright © 2018 Elsevier B.V. All rights reserved.

Aerosol Fragmentation Driven by Coupling of Acid-Base and Free-Radical Chemistry in the Heterogeneous Oxidation of Aqueous Citric Acid by OH Radicals.

PubMed

Liu, Matthew J; Wiegel, Aaron A; Wilson, Kevin R; Houle, Frances A

2017-08-10

A key uncertainty in the heterogeneous oxidation of carboxylic acids by hydroxyl radicals (OH) in aqueous-phase aerosol is how the free-radical reaction pathways might be altered by acid-base chemistry. In particular, if acid-base reactions occur concurrently with acyloxy radical formation and unimolecular decomposition of alkoxy radicals, there is a possibility that differences in reaction pathways impact the partitioning of organic carbon between the gas and aqueous phases. To examine these questions, a kinetic model is developed for the OH-initiated oxidation of citric acid aerosol at high relative humidity. The reaction scheme, containing both free-radical and acid-base elementary reaction steps with physically validated rate coefficients, accurately predicts the experimentally observed molecular composition, particle size, and average elemental composition of the aerosol upon oxidation. The difference between the two reaction channels centers on the reactivity of carboxylic acid groups. Free-radical reactions mainly add functional groups to the carbon skeleton of neutral citric acid, because carboxylic acid moieties deactivate the unimolecular fragmentation of alkoxy radicals. In contrast, the conjugate carboxylate groups originating from acid-base equilibria activate both acyloxy radical formation and carbon-carbon bond scission of alkoxy radicals, leading to the formation of low molecular weight, highly oxidized products such as oxalic and mesoxalic acid. Subsequent hydration of carbonyl groups in the oxidized products increases the aerosol hygroscopicity and accelerates the substantial water uptake and volume growth that accompany oxidation. These results frame the oxidative lifecycle of atmospheric aerosol: it is governed by feedbacks between reactions that first increase the particle oxidation state, then eventually promote water uptake and acid-base chemistry. When coupled to free-radical reactions, acid-base channels lead to formation of low molecular

Nutritional quality assessment of tomato fruits after exposure to uncoated and citric acid coated cerium oxide nanoparticles, bulk cerium oxide, cerium acetate and citric acid.

PubMed

Barrios, Ana Cecilia; Medina-Velo, Illya A; Zuverza-Mena, Nubia; Dominguez, Osvaldo E; Peralta-Videa, Jose R; Gardea-Torresdey, Jorge L

2017-01-01

Little is known about the effects of surface modification on the interaction of nanoparticles (NPs) with plants. Tomato (Solanum lycopersicum L.) plants were cultivated in potting soil amended with bare and citric acid coated nanoceria (nCeO 2, nCeO 2 +CA), cerium acetate (CeAc), bulk cerium oxide (bCeO 2 ) and citric acid (CA) at 0-500 mg kg -1 . Fruits were collected year-round until the harvesting time (210 days). Results showed that nCeO 2 +CA at 62.5, 250 and 500 mg kg -1 reduced dry weight by 54, 57, and 64% and total sugar by 84, 78, and 81%. At 62.5, 125, and 500 mg kg -1 nCeO 2 +CA decreased reducing sugar by 63, 75, and 52%, respectively and at 125 mg kg -1 reduced starch by 78%, compared to control. The bCeO 2 at 250 and 500 mg kg -1 , increased reducing sugar by 67 and 58%. In addition, when compared to controls, nCeO 2 at 500 mg kg -1 reduced B (28%), Fe (78%), Mn (33%), and Ca (59%). At 125 mg kg -1 decreased Al by 24%; while nCeO 2 +CA at 125 and 500 mg kg -1 increased B by 33%. On the other hand, bCeO 2 at 62.5 mg kg -1 increased Ca (267%), but at 250 mg kg -1 reduced Cu (52%), Mn (33%), and Mg (58%). Fruit macromolecules were mainly affected by nCeO 2 +CA, while nutritional elements by nCeO 2 ; however, all Ce treatments altered, in some way, the nutritional quality of tomato fruit. To our knowledge, this is the first study comparing effects of uncoated and coated nanoceria on tomato fruit quality. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Synthesis of WO{sub 3} nanoparticles by citric acid-assisted precipitation and evaluation of their photocatalytic properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sánchez-Martínez, D.; Martínez-de la Cruz, A., E-mail: azael70@yahoo.com.mx; López-Cuéllar, E.

Graphical abstract: Display Omitted Highlights: ► WO{sub 3} nanoparticles were synthesized by a simple citric acid-assisted precipitation. ► WO{sub 3} photocatalyst was able to the partial mineralization of rhB, IC and MO. ► WO{sub 3} can be considered as a photocatalyst active under visible light irradiation. -- Abstract: WO{sub 3} nanoparticles were synthesized by citric acid-assisted precipitation method using a 1:1.5 molar ratio of ammonium paratungstate hydrate (H{sub 42}N{sub 10}O{sub 42}W{sub 12}·xH{sub 2}O):citric acid (C{sub 6}H{sub 8}O{sub 7}). The formation of monoclinic crystal structure of WO{sub 3} at different temperatures was confirmed by X-ray powder diffraction (XRD). The characterization ofmore » the samples synthesized was complemented by transmission electron microscopy (TEM), Brunauer–Emmitt–Teller surface area (BET) and diffuse reflectance spectroscopy (DRS). According to the thermal treatment followed during the synthesis of WO{sub 3}, the morphology of the nanoparticles formed was characterized by rectangular and ovoid shapes. The photocatalytic activity of WO{sub 3} obtained under different experimental conditions was evaluated in the degradation of rhodamine B (rhB), indigo carmine (IC), methyl orange (MO), and Congo red (CR) in aqueous solution under UV and UV–vis radiation. The highest photocatalytic activity was observed in the sample obtained by thermal treatment at 700 °C. In general, the sequence of degradation of the organic dyes was: indigo carmine (IC) > rhodamine B (rhB) > methyl orange (MO) > Congo red (CR). The mineralization degree of organic dyes by WO{sub 3} photocatalysts was determined by total organic carbon analysis (TOC) reaching percentages of mineralization of 82% (rhB), 85% (IC), 28% (MO), and 7% (CR) for 96 h of lamp irradiation.« less

Palladium-platinum core-shell electrocatalysts for oxygen reduction reaction prepared with the assistance of citric acid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Lulu; Su, Dong; Zhu, Shangqian

Core–shell structure is a promising alternative to solid platinum (Pt) nanoparticles as electrocatalyst for oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). A simple method of preparing palladium (Pd)–platinum (Pt) core–shell catalysts (Pd@Pt/C) in a gram-batch was developed with the assistance of citric acid. The Pt shell deposition involves three different pathways: galvanic displacement reaction between Pd atoms and Pt cations, chemical reduction by citric acid, and reduction by negative charges on Pd surfaces. The uniform ultrathin (~0.4 nm) Pt shell was characterized by in situ X-ray diffraction (XRD) and high-angle annular dark-field scanning transmission electron microscopymore » (HAADF-STEM) images combined with electron energy loss spectroscopy (EELS). Compared with state-of-the-art Pt/C, the Pd@Pt/C core–shell catalyst showed 4 times higher Pt mass activity and much better durability upon potential cycling. As a result, both the mass activity and durability were comparable to that of Pd@Pt/C synthesized by a Cu-mediated-Pt-displacement method, which is more complicated and difficult for mass production.« less

Palladium-platinum core-shell electrocatalysts for oxygen reduction reaction prepared with the assistance of citric acid

DOE PAGES

Zhang, Lulu; Su, Dong; Zhu, Shangqian; ...

2016-04-26

Core–shell structure is a promising alternative to solid platinum (Pt) nanoparticles as electrocatalyst for oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). A simple method of preparing palladium (Pd)–platinum (Pt) core–shell catalysts (Pd@Pt/C) in a gram-batch was developed with the assistance of citric acid. The Pt shell deposition involves three different pathways: galvanic displacement reaction between Pd atoms and Pt cations, chemical reduction by citric acid, and reduction by negative charges on Pd surfaces. The uniform ultrathin (~0.4 nm) Pt shell was characterized by in situ X-ray diffraction (XRD) and high-angle annular dark-field scanning transmission electron microscopymore » (HAADF-STEM) images combined with electron energy loss spectroscopy (EELS). Compared with state-of-the-art Pt/C, the Pd@Pt/C core–shell catalyst showed 4 times higher Pt mass activity and much better durability upon potential cycling. As a result, both the mass activity and durability were comparable to that of Pd@Pt/C synthesized by a Cu-mediated-Pt-displacement method, which is more complicated and difficult for mass production.« less

Inhibition of lipid oxidation in frozen farmed ovate pompano (Trachinotus ovatus L.) fillets stored at -18 °C by chitosan coating incorporated with citric acid or licorice extract.

PubMed

Qiu, Xujian; Chen, Shengjun; Liu, Guangming; Lin, Hong

2016-08-01

Lipid oxidation can occur in fish fillets during long-term frozen storage and cause quality and nutrition loss, which is a major concern in the seafood industry. Our previous study showed that chitosan combined with citric acid or licorice extract can have a preserving effect on fresh fish fillets stored at 4 °C. It is of interest to further study their antioxidant effects on fish fillets during frozen storage. Chitosan, chitosan and citric acid, chitosan and licorice extract can inhibit primary and secondary lipid oxidation, as indicated by lower peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) values compared to the control samples. In addition, drip loss was decreased in the treatment samples. Both citric acid and licorice extract enhanced the antioxidant effects of chitosan. Among all the three treatments, chitosan and licorice extract showed the best antioxidant effects, reducing both PV and TBARS significantly at the end of storage. The combination of chitosan and citric acid or licorice extract showed significant antioxidant effects on ovate pompano fillets at -18 °C during 6 months of storage. They could be applied as natural antioxidant preservatives for use in seafood products or other meat products. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

Potentiometry: A Chromium (III) -- EDTA Complex

ERIC Educational Resources Information Center

Hoppe, J. I.; Howell, P. J.

1975-01-01

Describes an experiment that involves the preparation of a chromium (III)-EDTA compound, a study of its infrared spectrum, and the potentiometric determination of two successive acid dissociation constants. (Author/GS)

Aging deteriorated perception of urge-to-cough without changing cough reflex threshold to citric acid in female never-smokers.

PubMed

Ebihara, Satoru; Ebihara, Takae; Kanezaki, Masashi; Gui, Peijun; Yamasaki, Miyako; Arai, Hiroyuki; Kohzuki, Masahiro

2011-06-28

The effect of aging on the cognitive aspect of cough has not been studied yet. The purpose of this study is to investigate the aging effect on the perception of urge-to-cough in healthy individuals. Fourteen young, female, healthy never-smokers were recruited via public postings. Twelve elderly female healthy never-smokers were recruited from a nursing home residence. The cough reflex threshold and the urge-to-cough were evaluated by inhalation of citric acid. The cough reflex sensitivities were defined as the lowest concentration of citric acid that elicited two or more coughs (C2) and five or more coughs (C5). The urge-to-cough was evaluated using a modified the Borg scale. There was no significant difference in the cough reflex threshold to citric acid between young and elderly subjects. The urge-to-cough scores at the concentration of C2 and C5 were significantly smaller in the elderly than young subjects. The urge-to-cough log-log slope in elderly subjects (0.73 ± 0.71 point · L/g) was significantly gentler than those of young subjects (1.35 ± 0.53 point · L/g, p < 0.01). There were no significant differences in the urge-to-cough threshold estimated between young and elderly subjects. The cough reflex threshold did not differ between young and elderly subjects whereas cognition of urge-to-cough was significantly decreased in elderly subjects in female never-smokers. Objective monitoring of cough might be important in the elderly people.

Yarrowia lipolytica: a model yeast for citric acid production.

PubMed

Cavallo, Ema; Charreau, Hernán; Cerrutti, Patricia; Foresti, María Laura

2017-12-01

Every year more than 2 million tons of citric acid (CA) are produced around the world for industrial uses. Although initially extracted from citrus, the low profitability of the process and the increasing demand soon stimulated the search for more efficient methods to produce CA. Currently, most world CA demand (99%) is satisfied by fermentations with microorganisms, especially filamentous fungi and yeasts. CA production with yeasts has certain advantages over molds (e.g. higher productivity and easier cultivation), which in the last two decades have triggered a clear increase in publications and patents devoted to the use of yeasts in this field. Yarrowia lipolytica has become a model yeast that proved to be successful in different production systems. Considering the current interest evidenced in the literature, the most significant information on CA production using Y. lipolytica is summarized. The relevance on CA yields of key factors such as strains, media formulation, environmental conditions and production regimes is thoroughly discussed, with particular focus on increasing CA productivity. Besides, the possibility of tuning the mentioned variables to reduce concomitant isocitric acid production-the biggest disadvantage of using yeasts-is analyzed. Available methods for CA purification/quantification are also discussed. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Citric acid functionalized carbon materials for fuel cell applications

NASA Astrophysics Data System (ADS)

Poh, Chee Kok; Lim, San Hua; Pan, Hui; Lin, Jianyi; Lee, Jim Yang

Carbon materials can be easily functionalized using citric acid (CA) treatment. The CA modification of carbon materials is both simple and effective. It requires no prolonged heating, filtration and washing, and produces more functional groups such as carboxyl and hydroxide on CA-modified carbon nanotubes and XC72 carbon blacks than on HNO 3-H 2SO 4 oxidized carbon nanotubes and as-purchased XC72. Platinum nanoparticles are deposited on these functionalized carbon materials by means of a microwave-assisted polyol process. The investigations using TEM, XRD, FTIR and TGA indicate that CA modification creates more functional groups and thus deposits more Pt nanoparticles with smaller average particle size on the surface of carbon materials. Electrochemical studies of the Pt/C samples for methanol oxidation reveal higher activity for Pt on CA-modified carbon materials. It is therefore considered that this method can find important applications in reducing the cost and improving performance of proton-exchange membrane fuel cells.

Influence of citric acid on the surface texture of glass ionomer restorative materials

PubMed Central

Reddy, Dappili Swami Ranga; Kumar, Ramachandran Anil; Venkatesan, Sokkalingam Mothilal; Narayan, Gopal Shankar; Duraivel, Dasarathan; Indra, Rajamani

2014-01-01

Aim: This study determined the effectiveness of G-coat plus surface protective agent over petroleum jelly on the surface texture of conventional Glass ionomer restorative materials. Materials and Methods: Three chemically cured conventional glass ionomer restorative materials type II, type IX and ketac molar were evaluated in this study. Sixty specimens were made for each restorative material. They were divided into two groups of thirty specimens each. Of the sixty specimens, thirty were coated with G-coat plus (a nano-filler coating) and the rest with petroleum jelly. Thirty samples of both protective coating agents were randomly divided into six groups of five specimens and conditioned in citric acid solutions of differing pH (pH 2, 3, 4, 5, 6 & 7). Each specimen was kept in citric acid for three hours a day, and the rest of time stored in salivary substitute. This procedure was repeated for 8 days. After conditioning, the surface roughness (Ra, μm) of each specimen was measured using a surface profilometer (Taylor & Habson, UK). Data was analyzed using one-way analysis of variance (ANOVA) and Tukey's HSD test at a significance level of 0.05. Results: The surface textures of all the tested glass ionomer restorative materials protected with G-coat plus were not significantly affected by acids at low pH. The surface textures of all the tested glass ionomer restorative materials protected with petroleum jelly coating were significantly affected by acids at low pH. Conclusion: The effects of pH on the surface texture of glass ionomer restoratives are material dependent. Among all the materials tested the surface texture of Type II GIC (Group I) revealed marked deterioration when conditioned in solutions of low pH and was statistically significant. Hence, a protective coating either with G-coat plus or with light polymerized low viscosity unfilled resin adhesives is mandatory for all the glass ionomer restorations to increase the wear resistance of the restorative

Influence of citric acid on the surface texture of glass ionomer restorative materials.

PubMed

Reddy, Dappili Swami Ranga; Kumar, Ramachandran Anil; Venkatesan, Sokkalingam Mothilal; Narayan, Gopal Shankar; Duraivel, Dasarathan; Indra, Rajamani

2014-09-01

This study determined the effectiveness of G-coat plus surface protective agent over petroleum jelly on the surface texture of conventional Glass ionomer restorative materials. Three chemically cured conventional glass ionomer restorative materials type II, type IX and ketac molar were evaluated in this study. Sixty specimens were made for each restorative material. They were divided into two groups of thirty specimens each. Of the sixty specimens, thirty were coated with G-coat plus (a nano-filler coating) and the rest with petroleum jelly. Thirty samples of both protective coating agents were randomly divided into six groups of five specimens and conditioned in citric acid solutions of differing pH (pH 2, 3, 4, 5, 6 & 7). Each specimen was kept in citric acid for three hours a day, and the rest of time stored in salivary substitute. This procedure was repeated for 8 days. After conditioning, the surface roughness (Ra, μm) of each specimen was measured using a surface profilometer (Taylor & Habson, UK). Data was analyzed using one-way analysis of variance (ANOVA) and Tukey's HSD test at a significance level of 0.05. The surface textures of all the tested glass ionomer restorative materials protected with G-coat plus were not significantly affected by acids at low pH. The surface textures of all the tested glass ionomer restorative materials protected with petroleum jelly coating were significantly affected by acids at low pH. The effects of pH on the surface texture of glass ionomer restoratives are material dependent. Among all the materials tested the surface texture of Type II GIC (Group I) revealed marked deterioration when conditioned in solutions of low pH and was statistically significant. Hence, a protective coating either with G-coat plus or with light polymerized low viscosity unfilled resin adhesives is mandatory for all the glass ionomer restorations to increase the wear resistance of the restorative materials.

Recovery of manganese from manganese oxide ores in the EDTA solution

NASA Astrophysics Data System (ADS)

Zhang, Chao; Wang, Shuai; Cao, Zhan-fang; Zhong, Hong

2018-04-01

A new process has been experimentally and theoretically established for the recovery of manganese from manganese oxide ores, mainly including the reductive leaching of manganese by ethylenediaminetetraacetic acid (EDTA), EDTA recovery, and manganese electrolysis. The experimental conditions for this process were investigated. Moderate leaching environment by EDTA with the pH in the range of 5-6 is of benefit to leach manganese from some manganese oxide ores with high-content impurities, such as iron and aluminum. Most of EDTA can be recovered by acidification. A small amount of the residual EDTA in the electrolyte can prevent the generation of anode mud. In addition, trimanganese tetroxide (Mn3O4) can be obtained by the roasting of the EDTA-Mn crystallized product.

EDTA-temperature-Induced pseudohematocytopenia in a patient with multiple myeloma.

PubMed

Zhang, Lixia; Pan, Shiyang; Zhang, Jie; Lu, Lin; Xie, Erfu; Ye, Qin

2012-01-01

Platelet clumping caused by ethylenediamine tetraacetic acid (EDTA) and erythrocyte agglutination caused by cold agglutinins are often found in clinical findings. However, erythrocyte agglutination induced by EDTA has not been reported as yet. Spurious low red blood cell (RBC), white blood cell (WBC), and platelet counts were observed in a patient blood sample collected in EDTA in vitro at room temperature and 37 degrees C. However, the phenomena were only observed in the sodium citrate and heparin anticoagulated blood at room temperature, but not at 37 degrees C. Both erythrocyte agglutination and platelet clumping were observed in the peripheral blood smear. These data suggest an EDTA-temperature-induced pseudohematocytopenia. It is a very rare phenomenon to observe erythrocyte agglutination induced by EDTA and temperature.

Effects of chelating agents on the mineral content of root canal dentin.

PubMed

Cobankara, Funda Kont; Erdogan, Hilal; Hamurcu, Mehmet

2011-12-01

The objective of this in vitro study was to assess the effect of several chelating agents on the mineral content of root dentin. Extracted human mandibular incisor roots were prepared and divided into groups according to the following irrigation protocols: 1) 17% ethylenediaminetetraacetic acid (EDTA); 2) 10% citric acid solution; 3) 18% etidronate; 4) 2.25% peracetic acid; 5) and deionized water (control). Dentin chips were obtained (Gates-Glidden nos. 3, 4, and 5). The levels of different minerals were analyzed with the use of inductively coupled plasma-atomic emission spectrometry (ICP-AES). 1) Peracetic acid significantly decreased P, K, Mg, Na, and S levels compared with the other groups (P < .05). 2) S decreased by different levels in all of the chelating solutions (P < .05), and the greatest decrease was observed in peracetic acid. 3) Ca levels significantly decreased in peracetic acid, citric acid, and EDTA (P < .05). 4) Mn levels significantly decreased in the citric acid and peracetic acid groups (P < .05). 5) Na and Zn levels significantly decreased in the peracetic acid, citric acid, and etidronate groups (P < .05). The chelation agents can create different effects on mineral contents of root dentin, so it is important to know what effects each solution will have on root dentin before their clinical use. In addition, according to the results of this in vitro study, it might be recommended that peracetic acid, in particular, should be used with caution. Copyright © 2011 Mosby, Inc. All rights reserved.

Synthesis of high intrinsic loss power aqueous ferrofluids of iron oxide nanoparticles by citric acid-assisted hydrothermal-reduction route

DOE Office of Scientific and Technical Information (OSTI.GOV)

Behdadfar, Behshid, E-mail: bbehdadfar@ma.iut.ac.ir; Kermanpur, Ahmad; Sadeghi-Aliabadi, Hojjat

Monodispersed aqueous ferrofluids of iron oxide nanoparticle were synthesized by hydrothermal-reduction route. They were characterized by X-ray diffraction analysis, Fourier transform infrared spectroscopy, scanning and transmission electron microscopy and dynamic light scattering. The results showed that certain concentrations of citric acid (CA) are required to obtain only magnetic iron oxides with mean particle sizes around 8 nm. CA acts as a modulator and reducing agent in iron oxide formation which controls nanoparticle size. The XRD, magnetic and heating measurements showed that the temperature and time of hydrothermal reaction can affect the magnetic properties of obtained ferrofluids. The synthesized ferrofluids weremore » stable at pH 7. Their mean hydrodynamic size was around 80 nm with polydispersity index (PDI) of 0.158. The calculated intrinsic loss power (ILP) was 9.4 nHm{sup 2}/kg. So this clean and cheap route is an efficient way to synthesize high ILP aqueous ferrofluids applicable in magnetic hyperthermia. - Graphical abstract: Monodispersed aqueous ferrofluids of iron oxide nanoparticles were synthesized by hydrothermal-reduction method with citric acid as reductant which is an efficient way to synthesize aqueous ferrofluids applicable in magnetic hyperthermia. Highlights: Black-Right-Pointing-Pointer Aqueous iron oxide ferrofluids were synthesized by hydrothermal-reduction route. Black-Right-Pointing-Pointer Citric acid acted as reducing agent and surfactant in the route. Black-Right-Pointing-Pointer This is a facile, low energy and environmental friendly route. Black-Right-Pointing-Pointer The aqueous iron oxide ferrofluids were monodispersed and stable at pH of 7. Black-Right-Pointing-Pointer The calculated intrinsic loss power of the synthesized ferrofluids was very high.« less