A study on citric acid by-product as an energy source for Japanese quail

The increasing worldwide production of citric acid by the fermentation of substrates for use as a flavoring and a preservative in foods has resulted in the generation of large amounts of waste and by-products from fermented. There is a challenge to reduce the waste from these products by using them as animal feed. An experiment was conducted to study the utilization of citric acid by-products (CABP) as a feed ingredient in Japanese quail diets. A total of 560 1-day-old quail chicks were randomly distributed into five groups, with CABP included at 0, 3, 6, 9, and 12% of the diets. Each treatment had four replicate pens of 28 birds per pen throughout the 42-day trial period. CABP inclusion at 9 or 12% of the diet, respectively, resulted in a decrease in feed intake of 5.90 and 9.52%, body weight of 5.67 and 9.16%, and body weight gain of 5.44 and 9.97%, compared with the control diet (p < 0.05). Carcass traits and relative organ weights were not significantly different among the treatments (p > 0.05). The 12% CABP group showed a decrease in the digestibility of crude protein and apparent metabolizable energy, but there was an increase in the amount of crude fiber compared with the control diet (p < 0.05). The utilization of CABP in diets can reduce feed costs leading to increased investment returns. In conclusion, CABP can be included at up to 6% of quail diets without significant effects on growth performance or nutrient digestibility.

Biotechnological valorization of cashew apple juice for the production of citric acid by a local strain of Aspergillus niger LCFS 5

Background

This work investigates the production of citric acid from cashew apple juice, an abundant waste in the processing of cashew, using a local strain of Aspergillus niger and the application of the citric acid as a coagulant for the production of soy cheese. Fungal isolates were obtained from a cashew plantation in Ogbomoso, Nigeria, using potato dextrose agar. Further screening was undertaken to determine the qualitative strength of acid production by the fungi on Czapek-Dox agar supplemented with bromocresol green, with the development of yellow zone taken as an indication of citric acid production. Thereafter, the best producing strain was cultivated in a cashew apple juice medium.

Results

Out of 150 fungal isolates generated from the cashew plantation, 92 (61.3%), 44 (29.3%) and 14 (9.3%) were obtained from cashew fruits, soil and cashew tree surfaces, respectively. Different strains of fungi isolated include Aspergillus niger, A. flavus, A. foetidus, A. heteromorphus, A. nidulans and A. viridinutans. The isolates produced yellow zonation of 0.4–5.5 cm on modified Czapek-Dox agar; the highest was observed for a strain of A. niger LCFS 5, which was identified using molecular tools. In the formulated cashew apple juice medium, the citric acid yield of LCFS 5 ranged 16.0–92.8 g/l with the peak obtained on the 10th day of fermentation. The citric acid produced was recovered using the double precipitation method with Ca(OH)₂ and H₂SO₄ having ≈ 70% purity of citric acid on HPLC. The citric acid acted as a coagulant to produce soy cheese with 66.67% acceptability by panelists.

Conclusion

This work has extended the frontiers of valorization of cashew waste by a strain of A. niger to produce citric acid in high yield, with potential application in food industries.

Real-time co-site optical microscopy study on the morphological changes of the dentine's surface after citric acid and sodium hypochlorite: a single-tooth model

BACKGROUND

To this day, the effects of sodium hypochlorite and chelating agents on the smear layer and on the dentine's surface, remain not fully examined. The study is aimed to analyze the dentine's surface treated with 40% citric acid and 5.25% sodium hypochlorite according to two irrigation protocols.

MATERIALS AND METHODS

The study employed a computer-controlled Nikon Eclipse LV100 optical microscope. Ten roots split longitudinally with canals prepared mechanically using the MTwo system to a size of 40/04 were observed. The root halves were divided into two study groups, one half in each of the groups. According to two irrigation protocols, the dentine's surface was irrigated with 40% citric acid and 5.25% sodium hypochlorite, separated with water. Dentine surface was observed in a fixed place and photographed in 500 × magnification after each irrigation stage. The obtained images were then analyzed using computer software (NIS-Elements AR, GIMP-2.6, ImageJ 1.45s).

RESULTS

Various speed of removal of the smear layer and varied morphological changes of the dentine's surface were observed in both examined groups. Double irrigation of the dentine with citric acid for 30 s resulted in complete removal of the smear layer, and double irrigation for 60 s resulted in increased mean diameter of the dentine tubules (degradation of the dentine's surface).

CONCLUSIONS

Double alternating irrigation with citric acid and sodium hypochlorite for 30 s yielded satisfactory results, while double irrigation for 60 s resulted in increased mean diameter of the dentine tubules. A real time assessment of the dentine's surface changes after both tested solutions can improve understanding of the phenomena that occur during the irrigation and as a result it might help to improve clinical outcomes in root canal treatment.

Eco-friendly rice husk pre-treatment for preparing biogenic silica: Gluconic acid and citric acid comparative study

Carboxylic acid leaching has been established eco-friendly pre-treatment method for producing biogenic silica (BSi) from rice husk. The most urgent issue is for carboxylic acid to promote new readily biodegradable acids and enhance carboxylic acid sustainability in BSi preparation. This research investigates gluconic acid (GA) applicability for biogenic silica preparation from rice husk compared with citric acid (CA). The results demonstrated that GA was preferable to CA on BSi recovery with 89.91% efficiency. Although GA leaching promoted slightly higher silica loss, the primary metal alkali impurities, such as K₂O, Na₂O, and Al₂O_3, were effectively removed at 92-93%, 89-93%, 95-97%, respectively. The combination effect of silica loss and high removal impurities resulted in lower rice husk thermal decomposition activation energy. The characteristics of BSi prepared by GA leaching were comparable with CA leaching, mainly mesoporous with 114.06 m²/g of specific surface area and 0.23 cm³/g of the pore volume. In addition, GA leaching was environmentally better than CA leaching, indicated by minor contribution to all environmental impact indices. The findings suggested that GA could be a potential replacement for prevalent carboxylic acids in BSi preparation.

Effective removal of heavy metals from water using porous lignin-based adsorbents

Multifunctional composite materials are the key to improving removal capacity and environmental utility. Here, the adsorbent (SLCA) was obtained by free-radical polymerization of acrylic acid with sodium lignosulfonate and citric acid. FTIR, SEM, TGA and XPS characterization methods were used to prove the structure and properties of SLCA adsorbents. The maximum uptake capacities of the optimized SLCA adsorbent is 276 mg g^-1 of Cu²⁺ and 323 mg g^-1 of Pb²⁺, respectively. The Langmuir isotherm and the second-order kinetic model were established to illustrate that the capture of Cu²⁺ and Pb²⁺ by the adsorbent belongs to chemisorption on the monolayer. XPS analysis confirmed that complexation and electrostatic attraction are the mechanism of pollutant removal. Not only that, as-resulting adsorbent revealed no significant adsorption cycle efficiency reduction even after 5 runs of sorption-desorption cycle, manifesting that it is of great stability and could be regarded as a promising candidate adsorbent. The purpose of this research was to develop a green lignin-based adsorbent with strong environmental protection and regeneration ability based on cheap polyacrylic resin.

Assessment and Establishment of Correlation between Reactive Oxidation Species, Citric Acid, and Fructose Level in Infertile Male Individuals: A Machine-Learning Approach

Background:

Biochemical complexity of seminal plasma and obesity has an important role in male infertility (MI); so far, it has not been possible to provide evidence of clinical significance for all of them.

Aims:

Our goal here is to evaluate the correlation between biochemical markers with semen parameters, which might play a role in MI.

Study Setting and Design:

We enlisted 100 infertile men as patients and 50 fertile men as controls to evaluate the sperm parameters and biochemical markers in ascertaining MI.

Materials and Methods:

Semen analyses, seminal fructose, citric acid, and reactive oxidation species (ROS) were measured in 100 patients and 50 controls.

Statistical Analysis:

Descriptive statistics, an independent t-test, Pearson correlation, and machine-learning approaches were used to integrate the various biochemical and seminal parameters measured to quantify the inter-relatedness between these measurements.

Results:

Pearson correlation results showed a significant positive correlation between body mass index (BMI) and fructose levels. Citric acid had a positive correlation with sperm count, morphology, motility, and volume but displayed a negative correlation with BMI and basal metabolic rate (BMR). However, BMI and BMR had a positive correlation with ROS. Sperm count, morphology, and motility were negative correlations with ROS. The machine-learning approach detected that pH was the most critical parameter with an inverse effect on citric acid, and BMI and motility were the most critical parameter for ROS.

Conclusion:

We recommend that evaluation of biochemical markers of seminal fluid may benefit in understanding the etiology of MI based on the functionality of accessory glands and ROS levels.

Effect of mechanical activation on starch crosslinking with citric acid

The aim of this research was to investigate the influence of mechanical activation in a rotor-stator device on starch crosslinking with citric acid and the properties of the films obtained by the casting method. Two methods of preparation of the casting hydrogels were used: involving the introduction of chemical reagents before and after the mechanical activation. The films from the initial and mechanically activated hydrogels were characterized using optical and AFM microscopy, X-ray diffraction and FTIR-spectroscopy. The di-esterification degree, opacity, tensile properties and moisture resistance of the films were also studied. Mechanical activation of the starch hydrogels made it possible to make the films smoother and more transparent and to increase their tensile strength and moisture resistance. Pre-activation of the hydrogels without reagents showed better film performance than activation in the presence of citric acid.

Surface-modified magnetite nanoparticles affect lysozyme amyloid fibrillization

BACKGROUND

The surface of nanoparticles (NPs) is an important factor affecting the process of poly/peptides' amyloid aggregation. We have investigated the in vitro effect of trisodium citrate (TC), gum arabic (GA) and citric acid (CA) surface-modified magnetite nanoparticles (COAT-MNPs) on hen egg-white lysozyme (HEWL) amyloid fibrillization and mature HEWL fibrils.

METHODS

Dynamic light scattering (DLS) was used to characterize the physico-chemical properties of studied COAT-MNPs and determine the adsorption potential of their surface towards HEWL. The anti-amyloid properties were studied using thioflavin T (ThT) and tryptophan (Trp) intrinsic fluorescence assays, and atomic force microscopy (AFM). The morphology of amyloid aggregates was analyzed using Gwyddion software. The cytotoxicity of COAT-MNPs was determined utilizing Trypan blue (TB) assay.

RESULTS

Agents used for surface modification affect the COAT-MNPs physico-chemical properties and modulate their anti-amyloid potential. The results from ThT and intrinsic fluorescence showed that the inhibitory activities result from the more favorable interactions of COAT-MNPs with early pre-amyloid species, presumably reducing nuclei and oligomers formation necessary for amyloid fibrillization. COAT-MNPs also possess destroying potential, which is presumably caused by the interaction with hydrophobic residues of the fibrils, resulting in the interruption of an interface between β-sheets stabilizing the amyloid fibrils.

CONCLUSION

COAT-MNPs were able to inhibit HEWL fibrillization and destroy mature fibrils with different efficacy depending on their properties, TC-MNPs being the most potent nanoparticles.

GENERAL SIGNIFICANCE

The study reports findings regarding the general impact of nanoparticles' surface modifications on the amyloid aggregation of proteins.

Enhancement of resistance by poultry manure and plant hormones (salicylic acid & citric acid) against tobacco mosaic virus

Virus is the most menacing factor for plant, which causes enormous economic losses in agriculture worldwide. Tobacco mosaic virus is most hazardous virus among the plants that can spread through biological and non-biological sources. TMV is ancient virus that causes huge economic losses to pepper cucumber ornamental crops and tobacco. It can be controlled by reducing the population of vector through pesticide application. However, the rapid usage of synthetic chemicals causes environmental pollution and destroys our ecosystem. Consequently, different approaches just like natural derivatives should be adopted for the environmental friendly management for TMV. This in vitro study demonstrated the potential role of natural metabolites such as poultry manure and plant extracts such as salicylic acid and citric acid for the control of TMV. Two different concentrations of poultry manure 60G and 30G were used. Poultry manure was mixed with the soil at the time of sowing. Disease severity was minimum at maximum concentration as compared to the control. Meanwhile, two different concentrations of salicylic acid and citric acid 60% and 90% were applied by foliar sprayer after three-leaf stages. Disease severity was observed after 5, 10, 15, 20, 25, and 30 days after disease inoculation. Here also maximum concentration showed the minimum disease severity and higher concentration of both animal and plants extracts were used for following experiment. Quantitative real-time PCR (RT-qPCR) results demonstrated that different plant defense-related genes such as PR1a, PAL, PR5, NPR1, PRIb, and PDF1.2 were up-regulated. Furthermore, applications of each treatment-induced systemic resistance against a wide range of pathogen including TMV and fungal pathogen Botrytis cinerea.

Sustainable preparation of cellulose nanofibrils via choline chloride-citric acid deep eutectic solvent pretreatment combined with high-pressure homogenization

Developing green and simple methods for the preparation of cellulose nanofibrils (CNFs) is of great significance. Herein, a green deep eutectic solvent (DES) system based on choline chloride (ChCl) and citric acid (CA) is employed to pretreat cellulose fibers for the preparation of CNFs. The effect of the pretreatment temperature on the chemo-physical properties of the CNFs is comprehensively investigated. A high CNFs yield of up to 84.19% can be achieved under optimized conditions. The optimal CNFs show a narrow diameter distribution and length up to several microns, high crystallinity and thermal stability, as well as excellent dispersibility in water. Furthermore, semi-transparent and flexible cellulose nanopaper (CNP) was fabricated through a facile vacuum filtration process. The optimal CNP shows high tensile strength (175.15 MPa) and toughness (7.51 MJ/m³). Therefore, this work provides a sustainable and facile approach to fabricate CNFs and CNP, which can be potentially used for various high-tech applications.

Solid-State Cultivation of Aspergillus niger-Trichoderma reesei from Sugarcane Bagasse with Vinasse in Bench Packed-Bed Column Bioreactor

Solid-state cultivation (SSC) is microbial growth on solid supports under limited water conditions. Citric acid is a microbial aerobic metabolic product with several industrial applications, with production potential that can be obtained by SSF. Several wastes from agro-industries are used in SSF, such as sugarcane bagasse and vinasse. Cultures of mixed fungi or co-cultures are used in this SSF in order to complement the inoculum's xylanolytic enzymes for action on the lignocellulosic material (bagasse). Thus, this study aims to evaluate the effect of inoculum (Aspergillus niger and Trichoderma reesei consortium) in the production of citric acid from sugarcane bagasse impregnated with vinasse using bench packed-bed reactors (PBR). The results show the importance of T. reesei and A. niger in inoculum at a ratio of 50:50 and 25:75, suggesting the use of solid support due to the complementation of the hydrolytic enzymes. The highest concentration of citric acid, approximately 1000 mg L^-1, was obtained for 100 mm of bed height in 48 and 72 h, with maximum glucose yield in citric acid (2.2 mg _{citric acid} mg _glucose^-1). k_La indicates that maintaining solid moisture and liquid film thickness is important to keep the oxygen transfer in SSC.

Taste-induced facial responses in black-handed spider monkeys (Ateles geoffroyi)

Taste-induced facial expressions are thought to reflect the hedonic valence of an animal's gustatory experience. We therefore assessed taste-induced facial responses in six black-handed spider monkeys (Ateles geoffroyi) to water, sucrose, caffeine, citric acid and aspartame, representing the taste qualities sweet, bitter, and sour, respectively. We decided not to include salty-tasting substances as the concentrations of such tastants found in the fruits consumed by spider monkeys are below their taste preference threshold. We found that the monkeys displayed significant differences in their facial responses between substances, with significantly higher frequencies of licking, sucking, closed eyes, tongue protruding, mouth gaping and lip smacking in response to sucrose, a presumably pleasant stimulus. The response to caffeine and citric acid, in contrast, yielded the lowest frequencies of these behaviors, but the highest frequency of withdrawals from the stimulus, suggesting these substances are perceived as unpleasant. Lip stretching, a newly described behavior, was performed significantly more often in response to caffeine than to any other substance, suggesting an association with the response to bitter taste. The facial response to the artificial sweetener aspartame was generally similar to the response to water, corroborating the notion that Platyrrhines may be unable to detect its sweetness. Overall, the present study supports the idea of similarity of taste-induced facial responses in non-hominoid primates and humans, suggesting these displays to be evolutionarily conserved across the primate order.

Uncatalyzed and acid-aided microwave hydrothermal carbonization of orange peel waste

Orange, one of the most important fruit categories to be consumed across the world, when processed produces 50% of its weight as waste. Current waste management options for orange peel waste are inadequate to use the waste in wholesome and its disposal might lead to other environmental concerns. Here, we present microwave hydrothermal carbonization as an alternative to utilize the orange peel waste. Further, using citric acid to catalyze the microwave hydrothermal carbonization resulted in 30% higher maximal yield of hydrochar, and the hydrochar produced had better elemental, proximate and energy properties than hydrochar made during uncatalyzed microwave hydrothermal carbonization. Further, structural analysis revealed that citric acid promoted the formation of nanospheres during microwave hydrothermal carbonization. Taken together, microwave hydrothermal carbonization of orange peel waste using citric acid as a catalyst might not only help address the waste management concerns for orange peel waste, but also can produce end products of potential commercial value.

Ceiba pentandra cellulose crosslinked with citric acid for drug release systems

An alternative for the production of drug delivery system is proposed based on the Ceiba pentandra milkweed. The kapok cellulose was chemically crosslinked with citric acid (CA) at different CA proportions, and loaded with chlorhexidine diacetate (CHX) at different concentrations. Cellulose crosslinking was followed with FTIR and XPS analysis, and the CHX loading was determined using elemental analysis. In vitro studies showed a burst release within the first 2-3 h and the drug release kinetics was described with several models. In addition, the crosslinked Ceiba pentandra fibers did not exhibit a cytotoxic effect on human dermic fibroblasts. Results indicate that the crosslinked Ceiba pentandra fibers are a feasible material for the production of systems for drug release applications.

Gold Standard? Method of Citric Acid Solution Swallowing Test as a Screening Test for Patients with Tracheostomy

This study aimed to apply various ranges of citric acid levels in the mouth and T-cannula to compare the validity with instrumental aspiration measures in patients with tracheostomy. Sixty-one patients underwent the citric acid cough reflex test (CRT) and videofluoroscopic swallowing study (VFSS). Citric acid was delivered via facemask and T-cannula at concentrations of 0.4 mol/L, 0.6 mol/L, and 0.8 mol/L. Further, we recorded the coughing count and presence of ≥ 2 (C2) and ≥ 5 (C5) coughs. CRT via facemask at 0.4 mol/L C2, 0.6 mol/L C5, and 0.8 mol/L C2 and C5 were significantly associated with the presence of tracheal aspiration during VFSS. The sensitivity and specificity were optimized at 0.8 mol/L C2 for mouth inhalation and at 0.8 mol/L C5 for T-cannula inhalation. There was a significant difference in the coughing count during CRT at 0.4 mol/L and 0.8 mol/L via mouth inhalation between patients with or without tracheal aspiration, but not via T-cannula. The AUC for 0.8 mol/L facemask inhalation was 0.701. The optimal cut-off value of coughing count was thrice with 84.62% sensitivity and 50.00% specificity on the ROC curve. Afferent sensory nerve desensitization around and below the tracheostomy site could affect coughing reflex initiation and decrease the sensitivity of detecting aspiration in tracheotomized patients. The citric acid CRT via facemask can reliably detect tracheal aspiration and presence of coughing reflex compared to that via T-cannula in patients with tracheostomy.

Natural bio-based monomers for biomedical applications: a review

In recent years, synthetic and semi-synthetic polymer materials have been widely used in various applications. Especially concerning biomedical applications, their biocompatibility, biodegradability, and non-toxicity have increased the interest of researchers to discover and develop new products for the well-being of humanity. Among the synthetic and semi-synthetic materials, the use of natural bio-based monomeric materials presents a possible novel avenue for the development of new biocompatible, biodegradable, and non-toxic products. The purpose of this article is to review the information on the role of natural bio-based monomers in biomedical applications. Increased eco-friendliness, biocompatibility, biodegradability, non-toxicity, and intrinsic biological activity are some of the attributes which make itaconic, succinic, citric, hyaluronic, and glutamic acids suitable potential materials for biomedical applications. Herein, we summarize the most recent advances in the field over the past ten years and specifically highlight new and interesting discoveries in biomedical applications. Natural origin acid-based bio-monomers for biomedical applications.

Synergistic effect of citric acid and xenon light for inactivating foodborne pathogens on spinach leaves

The aim of this study was to evaluate the synergistic antimicrobial effect of xenon light (XL) and citric acid (CA) combination against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes on spinach leaves and determine the effect of XL-CA combination on quality of spinach leaves. The XL-CA combined treatment for 8 min synergistically decreased the cell counts of E. coli O157:H7 and S. Typhimurium by 5.25 and 5.05 log CFU/cm², respectively, and additively decreased the L. monocytogenes cells by 5.02 log unit on spinach. The mechanisms underlying synergistic lethal effect of the XL-CA combination were investigated. Qualitative and quantitative analyses revealed that the bacterial cell membrane damage was strongly associated with the synergistic antimicrobial effect of the XL-CA combination. Additionally, treatment with XL-CA combination for 8 min did not affect the quality attributes (color, total phenol contents, and texture) of spinach leaves. These results suggest that the XL-CA combination treatment can be effectively used to control major pathogens on fresh produce.

Biodegradable composite films/coatings of modified corn starch/gelatin for shelf life improvement of cucumber

Composite films comprising modified corn starch and gelatin were developed using a solvent casting technique. The effect of varied content of citric acid and gelatin on the functional properties of the corn starch and composite films, respectively, was investigated. Modified corn starch films enriched with 5% citric acid presented excellent film properties like solubility, swelling index, water vapor permeability, and mechanical property as compared to other films. Similarly, composite films enriched with a ratio (4:1) also exhibited excellent film properties like mechanical and opacity than other composite films. FTIR results confirmed the cross linking among the modified corn starch chains, which is responsible for the enhancement in the film properties. From SEM results, it was noticed that the modified corn starch films exhibited slightly rougher, less shiny than the composite films. Efficacy of the composite solution as a coating formulation in terms of the quality and shelf life of the cucumber investigated. From the results, it was noted that the composite film forming solution as a coating formulation has the potential to extend the shelf-life of the cucumbers additionally up to 16 days.

Citric acid inhibits Cd uptake by improving the preferential transport of Mn and triggering the defense response of amino acids in grains

Citric acid (CA) can regulate the balance of anions and cations in plants, and improve their resistance to heavy metals. It is not clear if foliar application with CA has any effect on migration of Cd and Mn in rice plant. In this work, a low-Cd-accumulating indica rice line (P7) and a high-Cd-accumulating line (HZ) were used to investigate the influence of CA on the transport of Cd and Mn as well as amino acid metabolism in grains. Content of Cd in grains and other organs increased with the increase of Cd content (0.1-2.4 mg kg^-1) in soil, while decreased with the foliar application with CA. With the increase of Cd content in rice grains, the content of most amino acids in HZ, P7, HZ+CA and P7 + CA showed an obvious decline trend. Foliar application with CA efficiently raised the Mn:Cd ratio in grains and nodes of both HZ and P7. Meanwhile, the expression levels of OsNramp2, 3 and 5 in panicles were efficiently enhanced by CA application when plants grew in soil with Cd content of 0.6-2.4 mg kg^-1. The increasing effect of CA on the content of 4 amino acids (i.e., Glu, Phe, Thr and Ala) in grains was related to varieties and Cd pollution. These results indicate that foliar application with CA can regulate the transport of Cd and Mn in the opposite directions in tissues and inhibit Cd accumulation in grains by enhancing expression of OsNRAMP 2, 3 or 5 and triggering the defense response of some amino acids in Cd-contaminated environment.

Reduced expression of CsPH8, a P-type ATPase gene, is the major factor leading to the low citrate accumulation in citrus leaves

Citrate is an important intermediate product for the biosynthesis of several metabolites in plants. As two important organs of the citrus plant, fruits and leaves have their own metabolites characteristics; among them, citrate is normally high in fruit juice sacs (JS) and low in leaves. In this study, citrate content and transcript levels of citrate synthesis, transport, storage, and utilization related genes were compared between leaves and fruit JS of Citrus reticulata cv. 'Huagan No. 2', C. grandis cv. 'Hirado Buntan', and C. sinensis cv. 'Anliu'. Results indicated that the citrate content in fruit JS was significantly higher than in leaves of each cultivar. Only the relative mRNA levels of a P-type proton pump gene, CsPH8, was significantly lower in leaves than in fruit JS of three citrus cultivars, while other genes related to citrate biosynthesis, transport, storage, and utilization were highly expressed in leaves as compared to fruit JS. Furthermore, CsPH8 transient and stable transformation in leaves indicated that the change in citrate content is highly consistent with the change of CsPH8 transcript levels. Taken together, our results strongly suggest that the low accumulation of citrate in citrus leaves is mainly due to the low expression level of CsPH8; additionally, the high level of expression of citrate-utilizing genes would prevent citrate accumulation in the leaf organ.

Esterification of sugarcane bagasse by citric acid for Pb2+ adsorption: effect of different chemical pretreatment methods

In this study, different pretreatment strategies of sugarcane bagasse prior to citric acid modification were investigated in terms of Pb²⁺ adsorption capacity. Pretreatment strategies included the use of NaOH, HCl, and C₂H₅OH in various concentrations. In order to fundamentally understand how these pretreatment methods affect the modification of sugarcane bagasse by citric acid as well as the Pb²⁺ adsorption capacity of sugarcane bagasse, three main components of sugarcane bagasse namely cellulose, hemicellulose, and lignin were isolated and esterified by citric acid under the same conditions. ATR-FTIR, XPS, SEM, and an analysis of the number of carboxylic acid groups were used to investigate the physicochemical and chemical properties of the materials. These three components were proved to participate in adsorption and induce the esterification with citric acid. Hence, pretreatment with ethanol and 0.01 M NaOH which could retain cellulose, hemicellulose, and lignin in sugarcane bagasse achieved a high Pb²⁺ adsorption capacity, i.e., 122.4 and 97 mg/g after the esterification with citric acid. In contrast, pretreatment with 0.5 M NaOH and 0.1 M HCl removed lignin and hemicellulose, leading to the lowest value of approximately 45 mg/g for citric acid esterified-pretreated sugarcane bagasse. XPS analysis and number of carboxylic group measurement confirmed the esterification between bagasse and citric acid. To understand the adsorption mechanism of adsorbent, two kinetic models including pseudo-first-order model and pseudo-second-order model were applied. The experimental data were well described by the pseudo-second-order model. The adsorption isotherm data were fitted Langmuir and Freundlich.

Effects of phosphorus on fruit soluble sugar and citric acid accumulations in citrus

Phosphorus (P) is one of the essential macro-elements for plants. Sugar and organic acid are important factors affecting sensory characteristics of citrus fruit quality. The aim of this study was to investigate how P fertilizer affects quality improvement particularly sucrose (Suc), fructose (Fru), glucose (Glu) and citric acid (CA) accumulations in Cara Cara navel. P fertilizer improved fruit quality of Cara Cara navel, as supported by decreasing titratable acid (TA), CA and increasing soluble solid (TSS), sugars and the ratio of TSS and TA. At the early stage of fruit development, P fertilizer had greater roles in degrading Suc into Fru and Glu due to the increased activities of Suc-degrading enzymes including acid invertase, neutral invertase and Suc synthase-cleavage activity. Coversely, at the mid and late stages of fruit development, P fertilizer had greater roles in re-synthesizing Suc due to the increased activities of Suc-synthesizing enzymes including Suc phosphate synthase and Suc synthase-synthetic activity. These results indicated that application of P fertilizer increased soluble sugars concentrations by improving Suc metabolism and sink strength in fruit conferred by the upregulations of the activities of Suc-degrading and Suc-synthesizing enzymes. P fertilizer decreased CA accumulations at least partially by inhibiting synthesis of CA due to the decreased activities of CA-synthesizing enzymes including citrate synthetase and phosphoenolpyruvate carboxylase. This study suggested that P fertilizer, particularly fertilized with 0.40 kg/plant, increased soluble sugars but decreased CA accumulations in citrus fruit.

Effect of ascorbic acid and citric acid on the quality of salted Chinese cabbage during storage

Changes in color, browning indices, enzyme activity, and physical and chemical quality during the storage period were investigated to assess the effectiveness of storage period extension along with the addition of ascorbic acid (AA) and citric acid (CA) to salted Chinese cabbage. After 16 days of storage, the change in chromaticity value showed treatment with 0.5% CA showed the lowest change in the brown index during the storage period. The control showed the highest residual activity of polyphenol oxidase among control, AA, and CA-treated salted cabbage. AA and CA treatment effectively inhibited the initial populations of microorganisms including total aerobic bacteria, lactic acid bacteria, and yeast and molds in salted Chinese cabbage during storage. Further, the texture, i.e., hardness, chewability, and elasticity, tended to decrease with increasing storage. These results suggest that treatment with AA could help maintain the quality of salted Chinese cabbage during the storage period.

Enhanced uptake of di-(2-ethylhexyl) phthalate by the influence of citric acid in Helianthus annuus cultivated in artificially contaminated soil

Di-(2-ethylhexyl) phthalic acid (DEHP) is the most extensively practiced plasticizer compound and a representative endocrine disrupting pollutant. Recently, the environmental impact and toxicological causes of DHEP on human health have been extensively investigated. DEHP uptake by plants is most significant biotransformation process of DEHP in environment. In this study, Helianthus annuus (H.annuus), vastly efficient in phytoremediation of polluted soil was selected to study the uptake and phytoremediation of DEHP in contaminated soil. In addition, the effect of citric acid on enhanced uptake and removal of DEHP was also investigated. The orders of biomass concentrations showed in the CA treatments were 200 mM (60.5 g) ˃ 150 mM (54.5) ˃ 100 mM (50.2 g) ˃ 50 mM (46.5 g). The maximum shoot accumulation of DHEP (20 mg/kg) was observed at 200 mM citric acid treatment compared to all other treatments (50, 100, and 150 mM). Significant difference of the antioxidant enzymes activity (CAT, 25.7, POD, 22.5 (μmol H₂O₂/min/g FW) and COD 5.6 U/g FW) was observed between control and CA treatments as well as different concentrations of CA treated plants. The maximum ALP (0.17 mg.g^-1soil.24 h^-1) and urease activities (1.65 mg.g^-1soil.24 h^-1) were observed at 200 mM CA amended soils. The application of citric acid was significantly enhanced the H.annuus growth as well as uptake of DEHP. The results explored that the citric acid has excellent potential for the enhanced uptake of DEHP in contaminated soil.

Use of citric acid for reducing CH4 and H2S emissions during storage of pig slurry and increasing biogas production: Lab- and pilot-scale test, and assessment

The use of sulfuric acid (SA) for reducing greenhouse gases (GHGs, mainly CH₄) emissions in manure management encounters with problems related with safety issue and increased H₂S emissions. In the present study, citric acid (CA) as an alternative to SA was assessed in the lab-scale experiment at various dosages (pH 5.0-7.0), and then confirmed in the pilot-scale tank (effective volume of 30 ton). During 35 d of pig slurry (PS) storage at 30 °C, it was found that the CA addition to initial pH down to 6.5 could lead negligible reduction, while 85-99% and 48-72% reduction of CH₄ and H₂S emissions were achieved at pH ≤ 6.0, respectively. The similar reduction performance was confirmed (control vs. pH 6.0) in the pilot-scale test, but, interestingly, two times higher CH₄ emissions of 123.7 kg CO₂ eq./ton PS was detected caused by the automatic temperature increase (≥35 °C). The pH of acidified PS did not exceed 6.5 during the whole storage period, while it was maintained 7.3-7.7 in the control. A continuous AD reactor fed with acidified PS exhibited a higher CH₄ yield of 10.0 m³ CH₄/ton PS, compared to the control (5.7 m³ CH₄/ton PS), due to the preservation of organic matters and added CA. In overall, about 8.5 [(4.4, storage) + (4.1, biogas)] kg of CH₄/ton PS was generated from raw PS and it was reduced to 7.8 [(0.7, storage) + (7.1, biogas)] kg of CH₄/ton PS by CA-acidification. Despite the carbon footprint for manufacturing CA, it was calculated that GHG reduction of 107 kg CO₂ eq./ton PS could be attained by CA-acidification. In terms of economic profit, it was estimated that 6.3 USD/ton PS can be gained by CA-acidification, while it was 2.4 USD/ton PS in case of control.

Efficacy of glycolic acid for the removal of calcium hydroxide from simulated internal Resorption cavities

OBJECTIVES

This study evaluated the efficacy of 5% and 10% glycolic acid solutions for the removal of calcium hydroxide medicament from artificial internal resorption cavities.

MATERIALS AND METHODS

A total of 170 human maxillary premolars were selected and artificial internal resorption cavities were prepared using round burs and 37% orthophosphoric acid in the apical third of the root halves. Entire canal and resorption cavity were filled with calcium hydroxide paste. Then, the specimens were assigned to 2 control groups or ten experimental groups according to the irrigating solutions used for medicament removal with and without activation with ultrasonic energy as following: 5% glycolic acid, 10% glycolic acid, 17% EDTA, and 10% citric acid and distilled water. The resorption cavities were examined under different magnifications using stereomicroscopy and scanning electron microscopy (SEM). The calcium hydroxide remnants in the resorption cavity were scored by 2 evaluators using a 4-scoring scale. The data were analyzed with Kruskal-Wallis H tests with 5% significance threshold.

RESULTS

There was no significant difference regarding the distribution of removal scores among non-activated solutions (P > 0.05). In activated groups, 10% glycolic acid irrigation removed significantly more amount of calcium hydroxide than EDTA and distilled water (P < 0.05). No significant difference was found between the efficacy of 10% glycolic and citric acid (P > 0.05). Citric acid, 5% glycolic acid, and EDTA showed similar removal scores (P > 0.05). Passive ultrasonic irrigation significantly improved calcium hydroxide removal scores in 10% glycolic acid, citric acid, and EDTA groups (P < 0.05). The SEM examination revealed that the specimens that were scored 0 are not entirely free of calcium hydroxide remnants.

CONCLUSION

Concentration of 10% glycolic acid removed significantly more calcium hydroxide paste from resorption cavities than EDTA when used with passive ultrasonic irrigation. Although passive ultrasonic irrigation favored medicament removal in all irrigating solutions, complete elimination of medicament remnants was unattainable.

CLINICAL RELEVANCE

This study showed the improved efficacy of ultrasonically activated 10% glycolic acid in removing the calcium hydroxide medicament from the internal resorption cavity.

Effect of coexisting manganese ion on the formation of haloacetic acids during chlorination

Haloacetic acids (HAAs) are a group of disinfection by-products formed by the reaction of dissolved organic matter (DOM) in source water and disinfectants in the drinking water treatment process. The formation of HAAs is known to be affected by several factors (e.g., pH, temperature, concentration, and DOM components in source water). However, the effects of coexisting substances, such as metal ions, on HAA formation are not well understood. In this study, HAA formation potentials (FPs) of model compounds of DOM and environmental waters in the presence or absence of manganese ion upon chlorination were compared. The results of experiments with model compounds of DOM showed that manganese ion promoted the formation of HAA from citric acid, trans-aconitic acid, and cis-aconitic acid. Even for a manganese concentration of less than 50 μg/L, which is the standard value of manganese in drinking water in the USA, EU, and Japan, manganese had great influence on the dichloroacetic acid FPs of these compounds. However, the manganese ion did not enhance the HAAFPs of the environmental waters tested. Nevertheless, manganese may have an effect on HAAFPs of environmental waters collected at the occurrence of an unusual growth of microorganisms, such as algal bloom.

Phosphorus recovery from soil through phosphorus extraction and retention on material: A comparison between batch extraction-retention and column percolation

Phosphorus (P) recovery from wastewater and soil is important for preventing the depletion of P resources; however, a method for recovering P from soil has not yet been developed. We designed and tested systems to recover P from excavated and in situ soil. P extraction from soil using citric acid, EDTA, and water is combined with P retention by calcium (Ca)- and magnesium (Mg)-containing material in both the batch extraction-retention and column percolation approach. In the batch extraction-retention test, Ca hydroxide retained more P than the other materials at 0.38-0.76 mg g^-1, and the P was retained as Ca phosphate-like minerals. The amount of P retained by materials using chelating solutions was higher than with water, regardless of the material. The amount of P in the Ca-containing materials after the column percolation test was higher than in the Mg-containing materials, with the exception of Ca carbonate. In the column percolation test, the percentage of P recovery from the available P in the soil was 4.9% and 3.5% using Ca hydroxide and Ca oxide with water, respectively, and the application of chelating solutions did not improve P recovery. In the batch extraction-retention test, the percentage of P recovery using Ca hydroxide and Ca oxide with water was the same as that obtained by the column percolation test; however, the use of chelating solutions could improve the P retention to more than 11% and 7%, respectively. These results demonstrate that more than 10% and 5% of the available P in the soil could be recovered using Ca hydroxide in the batch extraction-retention test with citric acid and EDTA solutions and the column percolation test with water, respectively. The P-retained material may be used as a source for the production of chemical fertilizer.

Effect of Fe2+ ions on gypsum precipitation during bulk crystallization of reverse osmosis concentrates

In reverse osmosis desalination, the concentrate is a saline solution that may become supersaturated. Heterogeneous nucleation of salts occurs at the membrane surface, resulting in the buildup of inorganic deposits on the membrane. The inorganic nucleation process, however, is complex in natural waters. Most studies focused primarily on single salt fouling of membranes, and related treatment for single solute systems. However, scale formation, especially gypsum, is affected by the presence of different salts and metals. In this wok, for the first time, we investigate the mixed precipitation of iron oxides and gypsum. The role of citric acid in the inhibition of precipitation was studied for different concentrations in both the absence and the presence of Fe²⁺. Conductivity and ion concentration measurements were used to estimate the formation time of gypsum. Scanning electron microscopy, X-Ray Diffraction (XDR) analysis, and Infra-Red spectroscopy analysis were used to provide structural information. Collected data showed that the presence of Fe²⁺ accelerates gypsum precipitation and shortens its induction time. Analytic results showed that gypsum crystals are greatly affected by the presence of Fe²⁺ ions, which generated needle shaped crystals. Citric acid can delay the induction time of gypsum precipitation. It also affects the morphology of gypsum crystals through adsorption mechanism. XDR diagrams revealed that the presence of citric acid (20 mg/L) can stabilize the bassanite phase (CaSO₄·½H₂O) for much longer periods. In the presence of Fe²⁺ ions, citric acid extends the induction time of calcium sulfate and minimizes the acceleration effect of Fe²⁺ ions. SEM images showed that the presence of ferrous ions during the chemical inhibition generates the β-hemihydrate form of calcium sulfate.

Co-amorphous formation of piroxicam-citric acid to generate supersaturation and improve skin permeation

The objective of this study was to prepare a co-amorphous formulation of piroxicam (PIR), a non-steroidal anti-inflammatory drug, and citric acid (CA), and evaluate its skin permeation ability. A spray-drying method was employed to prepare the co-amorphous formulation and its physical properties were characterized. X-ray powder diffraction and thermal analysis confirmed a homogeneous amorphous state, and the infrared spectra revealed intermolecular interactions between PIR and CA, suggesting formation of a co-amorphous formulation of PIR and CA. The PIR-CA co-amorphous formulation exhibited no crystallization for 60 days at 4/25/40°C with silica gel. The PIR-CA co-amorphous formulation increased the solubility of PIR in polyethylene glycol 400 compared with that of the pure drug, and physical mixture (PM) of PIR and CA, confirming a supersaturated state in the formulation. The PIR-CA co-amorphous formulation demonstrated higher skin permeation than PIR alone or PM of PIR and CA, and the flux value was consistent with the degree of saturation. Thus, the increase in the skin permeation of PIR from the PIR-CA co-amorphous formulation directly depended on the increased thermodynamic activity by supersaturation in the absence of interactions between the drug and co-former in the vehicle.

Development of pre-emergence herbicide based on Arabic gum-gelatin, apple pectin and savory essential oil nano-particles: A potential green alternative to metribuzin

This study was conducted as a plot experiment to investigate the phytotoxicity effects of nano-encapsulated savory essential oil (EO) when it is incorporated separately into carbohydrate and protein natural polymers (Arabic gum-gelatin, apple pectin and gelatin) and two cross-linkers including one poly acid and one enzyme (citric acid and transglutaminase enzyme). Each product was tested as a pre-emergence herbicide against amaranth and tomato. The evaluations also involved determining the stability, morphology, encapsulation efficiency and release properties of the prepared formulations. Coating the savory EO with cross-linked biopolymers enhanced its stability and herbicidal activity, compared to the EO nano-emulsion without any polymer or cross-linker. Among the tested formulations, the strongest inhibitory effect against amaranth germination and growth was caused by Arabic gum-gelatin and apple pectin biopolymers at the concentration of 3 ml/L of EO, when cross-linked with citric acid. These two treatments had slight effects on tomato seedlings, however. The suppressive ability of the formulations was almost similar and comparable to the chemical herbicide metribuzin (1.75 g/L). In conclusion, Arabic gum-gelatin and apple pectin cross-linked by citric acid containing savory EO can be considered as potential, green and safe replacements for metribuzin in organic tomato production.

Polyelectrolyte-functionalized reduced graphene oxide wrapped helical POMOF nanocomposites for bioenzyme-free colorimetric biosensing

For the sake of effective colorimetric sensing-pattern, a sensitive colorimetric sensor was conceived based on polyoxometalates based metal-organic frameworks (POMOFs) and polydiallyldimethylammonium chloride functionalized reduced graphene oxide (PDDA-rGO) for the first time, in which PDDA as a "glue" molecule turns rGO nanosheets into general platforms for bonding POMOFs nanoparticles. Herein, a new POMOF compound with fascinating helices-on-helices feature, [Ni₄(Trz)₆(H₂O)₂][SiW₁₂O₄₀]^.4H₂O (Trz = 1,2,4-triazole) (abbreviated as Ni₄SiW₁₂), was synthesized and characterized, then PDDA-rGO sheet as dispersive and conductive material was successfully introduced to Ni₄SiW₁₂ fabricating new PDDA-rGO/Ni₄SiW₁₂-n nanocomposites, (abbreviated as PMPG-n). The resulting PMPG-n nanocomposites as peroxidase mimetic show excellent catalytic activities under extreme condition (pH value 2.5), attributed to the nature and synergies from POMs, MOFs and PDDA-rGOs. Note that the peroxidase-like activity of PMPG-1 (the mass ratio of Ni₄SiW₁₂ to PDDA-rGO is 1:1) exhibits higher sensitivity (1-60 μM), faster response (10 min) and the lowest limit of detection (2.07 μM) among all reported materials to citric acid (CA) to date. This work opens up new application prospects in colorimetric sensing system for food quality control and safety, biotechnology and clinical diagnosis.

Effect of different gases on the sonochemical Cr(VI) reduction in the presence of citric acid

The sonochemical (850 kHz) Cr(VI) reduction (0.30 mM, pH 2) in the presence of citric acid (Cit, 2 mM) was analyzed under different working atmospheres: reactor open to air without sparging (ROAWS), and Ar, O₂, air and N₂ sparging. Hydrogen peroxide formation in pure water at pH 2 and KI dosimetry were also measured. Zero-order kinetics was observed in all cases. A complete Cr(VI) reduction after 180 min insonation was obtained with the ROAWS and under Ar, while a lower Cr(VI) reduction efficiency was achieved under the other conditions. The Cr(VI) reduction and H₂O₂ formation rates followed the order ROAWS ≅ Ar > air ≅ O₂ ≫ N₂, while for KI dosimetry the order was ROAWS ≫ O₂ ≅ air > Ar ≫ N₂. This indicates that H₂O₂ formation rate is a better measure of the system reactivity for Cr(VI) reduction. For air, O₂ and N₂, once the sparging was stopped, Cr(VI) reduction rate increased up to approximately the same value obtained for the ROAWS, suggesting that the sparging decreased the generation of reactive species and, thus, the Cr(VI) reduction rate. Nitrate production was measured at low concentrations (micromolar range) in the ROAWS, air and N₂ systems. Formic and acetic acids were detected as Cit degradation products. Reaction mechanisms were proposed. It can be concluded that the best condition for Cr(VI) removal is with the ROAWS because of a higher Cr(VI) reduction rate, no atmosphere control is required, and it is a less expensive system.

Catalytic activity of porous manganese oxides for benzene oxidation improved via citric acid solution combustion synthesis

Various manganese oxides (MnO_x) prepared via citric acid solution combustion synthesis were applied for catalytic oxidation of benzene. The results showed the ratios of citric acid/manganese nitrate in synthesizing process positively affected the physicochemical properties of MnO_x, e.g., BET (Brunauer-Emmett-Teller) surface area, porous structure, reducibility and so on, which were in close relationship with their catalytic performance. Of all the catalysts, the sample prepared at a citric acid/manganese nitrate ratio of 2:1 (C2M1) displayed the best catalytic activity with T₉₀ (the temperature when 90% of benzene was catalytically oxidized) of 212℃. Further investigation showed that C2M1 was Mn₂O₃ with abundant nano-pores, the largest surface area and the proper ratio of surface Mn⁴⁺/Mn³⁺, resulting in preferable low-temperature reducibility and abundant surface active adsorbed oxygen species. The analysis results of the in-situ Fourier transform infrared spectroscopy (in-situ FTIR) revealed that the benzene was successively oxidized to phenolate, o-benzoquinone, small molecules (such as maleates, acetates, and vinyl), and finally transformed to CO₂ and H₂O.

Inclusion of vitexin in β-cyclodextrin: preparation, characterization and expectorant/antitussive activities

The study aimed to include the isolated vitexin of Jatropha mutabilis in the β-cyclodextrin cavity to improve the solubility of this flavone. Its characterization was performed by techniques such as ¹H NMR/ROESY (Nuclear Magnetic Resonance Spectroscopy), FT-IR (Infrared Spectroscopy with Fourier Transform), SEM (Morphological analysis of IC by Scanning Electron Microscopy) and dissolution study in vitro. In addition, the following activities were evaluated in the animal models: expectorant, phenol red dosage in bronchoalveolar lavage and antitussive, cough induced by citric acid. In the characterization of the complex, interaction between hydrogens of ring B of vitexin and (H3) of β-CD was observed, in addition to changes in morphology. In the dissolution test, an increase in the rate of dissolution of vitexin was observed in the first 30 min for the CI vitexin/β-CD when compared with vitexin. Regarding the pharmacological activity, it was observed that the inclusion complex (IC) vitexin/β-CD in the equivalent doses of 0.2, 1 and 5 mg/kg of flavone presented higher expectorant activity when compared to vitexin (p < 0.05), suggesting increased bioavailability. As for the antitussive activity, both vitexin and the complex had similar effects and were dose independent. In the toxicity test using Artemia salina, vitexin and IC vitexin/β-CD were considered non-toxic. At last, the study efficacy of vitexin/β-CD IC as an expectorant and of vitexin as antitussive. All of these data are being described for the first time.

Synergistic bactericidal effect of hot water with citric acid against Escherichia coli O157:H7 biofilm formed on stainless steel

This study investigated the antimicrobial effect of hot water with citric acid against Escherichia coli O157:H7 biofilm on stainless steel (SS). Hot water (50, 60, or 70 °C) with 2% citric acid exhibited a synergistic bactericidal effect on the pathogen biofilm. It was revealed that hot water and citric acid combination induced sub-lethally injured cells. Additionally, mechanisms of the synergistic bactericidal effects of hot water with citric acid were identified through several approaches. In terms of biofilm matrix, hot water removes exopolysaccharides, a major component of extracellular polymeric substances (EPS), thereby increasing contact between surface cells and citric acid, resulting in a synergistic bactericidal effect. In terms of the cell itself, increased permeability of citric acid through cell membranes destructed by hot water promotes the inactivation of superoxide dismutase (SOD) in E. coli O157:H7, which induce synergistic generation of reactive oxygen species (ROS) which promote inactivation of cell by activating lipid peroxidation, resulting in destruction of the cell membrane. Therefore, it is interpreted that when hot water with citric acid is applied to E. coli O157:H7 biofilm, synergy effects on the biofilm matrix and cell itself have a complex interaction with each other, thus causing a dramatic synergistic bactericidal effect.

The states of water in tryptophan grafted hydroxypropyl methylcellulose hydrogels and their effect on the adsorption of methylene blue and rhodamine B

Tryptophan (Trp) decorated hydroxypropyl methylcellulose (HPMC) cryogels were prepared by a one-step reaction with citric acid. The increase of Trp content in the 3D network from 0 to 2.18 wt% increased the apparent density from 0.0267 g.cm^-3 to 0.0381 g.cm^-3 and the compression modulus from 94 kPa to 201 kPa, due to hydrophobic interactions between Trp molecules. The increase of Trp content in HPMC-Trp hydrogels increased the amount of non-freezing water, estimated from differential scanning calorimetry, and the amount of freezing water, which was determined by time-domain nuclear magnetic resonance. The adsorption capacity of methylene blue (MB) and rhodamine B (RB) on HPMC-Trp hydrogels increased with Trp content and the amount of freezing water. HPMC-Trp hydrogels could be recycled 6 times keeping the original adsorptive capacity. The diffusional constants of MB and RB tended to increase with Trp content. RB adsorbed on HPMC-Trp hydrogels presented a bathochromic shift of fluorescence.

One-pot fabrication of sacchachitin for production of TEMPO-oxidized sacchachitin nanofibers (TOSCNFs) utilized as scaffolds to enhance bone regeneration

One-pot fabrication of sacchachitin (SC) for mass-production was developed and optimized by selecting KOH as alkaline agent in depigmentation step and utilizing NaClO₂ as bleaching agent in subsequent step in the same pot. Overall yield of one-pot-fabricated SC was up to 35 %w/w of initial weight with a fibrous texture soft enough for mechanical disintegration into SC nanofibers (SCNFs) and better dispersion for producing TEMPO-oxidized SCNFs (T033SC). Both SCNFs and T033SC could form a 3D gelatinous scaffold into which MC3T3-E1 cells were attracted. Higher calcium-trapping ability of T033SC resulting from a greater extent of carboxylate groups provided an excellent bone regeneration environment that resulted in better outcomes of bone regeneration in a femur defect rat model compared to those with SCNFs possessed fewer carboxylate groups. In conclusion, biomaterial scaffolds based on TEMPO-oxidized SCNFs produced from one-pot fabricated SC showed great potential for bone regeneration due to unique physical and chemical properties.

Formulation of Effervescent Granule from Robusta Green Coffee Bean Ethanolic Extract (Coffea canephora)

INTRODUCTION

Robusta coffee (Coffea canephora) is one of the many crops cultivated in Aceh, and at present is only being used as a drink. Research has shown the potential of many pharmacological uses for coffee, including its use as a remedy to treat diabetes. Effervescent granules are one of the oral dosage forms that can not only mask the unpleasant taste of bioactive substances, but also have a high aesthetic value and can contain relatively large doses of bioactive substances. Previous research has shown that ethanolic extract of robusta green coffee beans at 100 mg/kg body weight (BW) rat yielded the highest percentage of glucose reduction. On the basis of that research, the dosage was used in this study to be formulated into effervescent granule.

AIMS

This study aimed to find the best formulation of effervescent granules preparation using various concentrations of effervescent salt that meets the general requirements of effervescent dosage forms. The concentrations of citric acid, tartaric acid, and sodium bicarbonate used in sequence were 7.35%, 14.7%, and 25% (F1); 8.08%, 16.17%, and 27.5% (F2); and 8.82%, 17.64%, and 30% (F3), respectively. Robusta green coffee beans were extracted using the maceration method.

RESULTS

Secondary metabolite screening of extract showed that it contained alkaloid, saponin, phenolic, and flavonoid metabolites. Effervescent granules were evaluated and F1 and F2 did not qualify the flowability standard of the granules, whereas F3 qualified in all the evaluation standards.

CONCLUSION

On the basis of these results, F3 produced the best effervescent granules that met the general standards of the effervescent dosage forms.

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

Introduction:

Irrigants remove or dissolve smear layer formed during instrumentation. Thus it is important to study the effect of different irrigant solutions on smear layer removal.

Objectives:

The aim of this study is to determine which irrigant effectively removes the smear layer from the coronal, middle, and apical third of the root canal.

Materials and Methodology:

One hundred and twenty single-rooted mandibular premolars were decoronated and biomechanical preparation was done through hand instrumentation up to size 40 k file with 2.5% NaOCl irrigation between each successive filing, followed by irrigation with 5 ml of saline. The teeth were divided into Groups I, II, III, and IV containing 30 samples each and irrigated with 5 ml of 17% ethylenediamine tetraacetic acid (EDTA), 10% Citric acid, 7% Maleic acid and normal saline respectively for 1 min and final irrigation was done with 5 ml of distilled water of each sample. The canals were dried with 2% absorbent paper points. The roots were then split with a chisel and mallet. One-half of each tooth was selected and then was analyzed using a scanning electron microscope. The dentinal surfaces were observed at the cervical, middle, and apical third with ×2000 for the smear layer. The scores were attributed, according to Torabinejad et al. rating system.

Results:

7% maleic acid and 10% citric acid both are equally effective in smear layer removal from coronal and middle third, but in apical third 7% maleic acid is more effective than 10% citric acid. Between citric acid and EDTA, both are equally effective in smear layer removal from coronal and middle third, but in apical third, 10% citric acid is more efficacious than 17% EDTA.

Conclusion:

Within the limitations of the study, it can be concluded that all three tested irrigants removed the smear layer from coronal, middle, and apical third. However, in apical third 7% maleic acid is the most efficacious irrigant in smear layer removal.

Selective metal leaching from technosols based on synthetic root exudate composition

This study focused on metal release from technosols induced by synthetic root exudate (SRE). The effect of SRE composition on metal release was studied using six technosols. This was done by treating the technosols with SRE solutions having varying concentrations of low molecular weight organic acids (LMWOAs), namely oxalic, citric, and malic acids. Consequently, the physico-chemical parameters (pH and electric conductivity), Ca, Mg, Fe, Zn, and Cu release (by atomic absorption spectroscopy, AAS), chemical changes (by Fourier transform infrared, FT-IR), and organic parameters (by fluorescence) were investigated. Metal release showed to be dependent on the SRE composition and technosol characteristics. Citric acid selectively released Ca, Mg, Zn, and Cu from technosols in a concentration-dependent manner; oxalic acid showed a significant role in the release of Mg and Fe. Under relatively high LMWOA concentrations, particulate organo-mineral complexes precipitated. Additionally, technosol weathering was seen by the dissolution of humic substances and ferriallophanes, which in turn caused metal release. However, re-precipitation of these phases showed to re-sorb metals, thus underestimating the role of LMWOAs in metal release. Therefore, the selective metal leaching was highly dependent on the SRE composition and LMWOA concentrations on one hand, and on the mineral, organic, and organo-mineral components of the technosols on the other. The understanding of such processes is crucial for proposing and implementing environmental management strategies to reduce metal leaching or for the beneficial re-usage of metals (e.g., for agromining) from technosols.

kawachii and Aspergillus oryzae

Citrate exporter CexA plays a key role in the production of citric acid in fungi; however, its role in intracellular metabolism has remained unclear. In this study, we comparably characterized homologous cexA genes in the white koji fungus Aspergillus luchuensis mut. kawachii and the yellow koji fungus Aspergillus oryzae, which exhibit high and low abilities, respectively, to produce citric acid. Disruption of cexA caused a significant decline of both extracellular and intracellular citric acid accumulation in Aspergillus kawachii, while overexpression of the A. kawachii cexA gene (AkcexA) into A. oryzae significantly enhanced both extracellular and intracellular citric acid accumulation in A. oryzae to a level comparable to that of A. kawachii. In addition, overexpression of two intrinsic cexA homologs (AocexA and AocexB) in A. oryzae also enhanced its extracellular and intracellular citric acid accumulation. Comprehensive analysis of intracellular metabolites from an AkcexA-overexpressing strain of A. oryzae compared with its control strain identified metabolic changes associated with intracellular citric acid accumulation via the glycolytic pathway, pentose phosphate pathway, and tricarboxylic acid cycle. Our results indicate that citric acid export enhances not only extracellular citric acid accumulation but also intracellular metabolic fluxes to generate citric acid.

Significant enhancement of citric acid production by Yarrowia lipolytica immobilized in bacterial cellulose-based carrier

The aim of this study was to improve the yield of citric acid (CA), an industrially valuable metabolite, obtained during Yarrowia lipolytica yeast culturing. To this end, Y. lipolytica cells were immobilized on a novel bacterial cellulose (BC) based carrier and subjected to four subsequent cycles of fed-batch culturing. During the fermentation process, yeasts metabolic stability, glucose consumption and CA production were analyzed. The results of our study have shown that BC-immobilized yeasts utilized more glucose than free cells and that the metabolic activity of BC-immobilized cells and the resultant CA production remained on a stable level throughout 4 fermentation batches, while the drop in free cells' metabolic stability and the consequent drop in CA production was observed with each subsequent batch. Also, the overall concentration of CA product was higher in immobilized vs. free yeasts (121-129 g/L vs. 99-110 g/L, respectively). The presented results indicate that the application of a BC carrier for Y. lipolytica culturing correlates not only with a higher yield of CA product but also with more stable and repeatable conditions of the biotechnological fermentation process. The results obtained in this study may find multiple biotechnological applications in which immobilization of various types of cells is required.

Multi-component design and in-situ synthesis of visible-light-driven SnO2/g-C3N4/diatomite composite for high-efficient photoreduction of Cr(VI) with the aid of citric acid

A novel ternary SnO₂/g-C₃N₄/diatomite (SCN/DE) nanocomposite was rationally designed and successfully synthesized via a two-step method with in-situ polymerization and self-assembling. Under visible light illumination, the resulting SCN/DE composite exhibited superior photocatalytic performance and good reusability for the photoreduction of Cr(VI) to Cr(III) in the presence of citric acid, the apparent rate constant of SCN/DE composite was up to around 22.68 times, 13.53 times and 8.65 times as much as those of g-C₃N₄ (CN), g-C₃N₄/diatomite (CN/DE) and SnO₂/g-C₃N₄ (SCN) composites, respectively. The citric acid is a co-catalyst (chelating agent) rather than a reactant during the reactive process. Besides, the intimate interface contact and ternary heterogeneous structure were established among the SnO₂, g-C₃N₄ and diatomite. The induced positive charged surface of diatomite should be the key factor in enhancing photoactivity of the resultant SCN/DE composite, which significantly accelerated the charge separation of photogenerated electron-hole pairs as well as improved the adsorption performance towards Cr (VI). In particular, a possible reduction pathway of Cr(VI) to Cr(III) by SCN/DE composite with the assistance of citric acid was first investigated and proposed. This work provides a novel strategy for synthesizing highly efficient mineral-based photocatalysts with great promising application foreground for Cr(VI)-containing wastewater treatment.

Removal of Cd, Pb, Zn, Cu in smelter soil by citric acid leaching

Soil washing has been verified as a feasible technology for source reduction for contaminated soil with heavy metals. We conducted batch and column leaching experiments to investigate the removal of Cd, Pb, Cu and Zn from smelter soil by citric acid. The removal efficiency of heavy metals by batch leaching reached a maximum (89.1% Cd, 26.8% Pb, 41.7% Zn, 14.2% Cu) at a concentration of 0.1 M and a pH of 5. Citric acid also removed 91.3%, 11.1%, 39.2% and 11.1% of Cd, Pb, Zn, and Cu respectively after column leaching. Citric acid mainly removed exchangeable, carbonate bound and oxide bound Cd, Pb, Cu and Zn fractions. Vertical distributions of Cd, Cu and Zn similarly increased with increasing soil depth. Chestnut shells were applied to the recovery of citric acid from the waste eluent, which removed 84.4%, 97.5%, 74.6%, 70.3% of Cd, Pb, Zn, and Cu, respectively, due to chestnut shell chelation. Fresh and regenerated citric acid was used in batch leaching of heavy metal-contaminated soil, and they showed similar ability to extract heavy metals.

Safe natural bio-pigment production by Monascus purpureus using mixed carbon sources with cytotoxicity evaluation on root tips of Allium cepa L

By increasing the undesirable side effects of synthetic food pigments on human health, using safe natural food pigment become an urgent issue. Incorporate corn starch with oils conducted a high impact on red pigment production by Monascus purpureus. Fortification the medium with sesame oil raised the pigment production by 80% and the dry mass by 63% compared with free oil medium. Response surface methodology maximizes the production with 114.6% (12.8 A₅₀₀) using medium constituents (g/l); Sesame oil 5; Corn starch 30; Yeast extract 1.5; KH₂PO₄ 2.5 and MgSO₄.7H₂O 0.1. After evaluating red pigment stability in three common food components, citric acid showed a great effect on residual stability percentage compared with ascorbic and salicylic acid which decrease slightly the residual stability percentage at light and dark conditions. The mitotic index of red pigment was lower than the negative control at all tested concentrations. Different types of mitotic chromosomal abnormalities e.g. lagging chromosome, chromosomal bridge, chromosome and chromatin fragments, outside chromosome, chromosomal stickiness and micro nuclei were recorded. Insignificant increase in total mitotic aberrations percentage in all tested root tips treated with all concentrations of red pigment (1.23, 1.58, 1.63, 2.32 and 2.40%) compared with negative control (0.91%). There was a significant increase in total aberrations percentage after treatment with all concentrations (10, 15, 20 and 25%) of positive control (2.93, 3.00, 3.55 and 6.53 respectively) except (5%) which was insignificant (2.71%). From the previous data, this red pigment can be used as an alternative safe pigment in the food industry.

Fabrication and characterization of carboxymethyl guar gum nanocomposite for application of wound healing

Bio scaffolds used for cutaneous tissue regeneration is a challenging issue in the healthcare system. To help this problem, we aimed to report on fabrication and characterization of citric acid cross-linked carboxymethyl guar gum (CMGG) nanocomposite films loaded with ciprofloxacin for faster wound healing application. Differential scanning calorimeter (DSC) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy studies, dynamic light scattering (DLS), scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used as analytical techniques for characterization of the nanocomposite film. The morphological characters of nanocomposite film were determined by SEM. The prepared scaffolds were evaluated for the carboxyl content and swelling ratio. Ciprofloxacin was loaded into scaffold and drug release was studied at pH 7.4. The hemolysis assay was used to study the biocompatibility of scaffold films. The formation of ester cross-links between citric acid and CMGG was confirmed by DSC and ATR- FTIR. The total carboxyl content of scaffold was found to be decreased when the amount of CMGG was increased. The swelling of scaffold film was found to be decreased with increase in curing temperature and time. CMGG scaffold films showed high drug loading with non-Fickian release mechanism suggesting controlled release of drug. In vivo wound healing studies were carried out for 5 days. In this study we observed a faster wound healing effect within 5 days by incorporation of ciprofloxacin in the CMGG film and found biocompatible. Hence, these Nanocomposite films show greater potential in treating wounds.

The concentration of citric acid as dental root conditioner influences the behavior of fibroblasts from human periodontal ligament

OBJECTIVE

This study investigated the behavior of fibroblasts from human periodontal ligament (hPLF) cultured on dental roots subjected to different protocols of citric acid conditioning.

MATERIALS AND METHODS

32 human teeth extracted due to advanced periodontal disease provided 63 radicular fragments, which were randomly divided in groups according to the treatment given to the surface: rinsing with saline solution for 90 s (C), 10 % citric acid (CA10), or 50 % citric acid (CA50). The treatments were applied during 90 s, 120 s and 180 s (n = 9). hPLF were cultured for 24, 48 and 72 h (n = 3) on the treated samples and analyzed by scanning electron microscopy (SEM) for surface area covered by cells and dentinal tubules widening.

RESULTS

Excepting group C, all the other groups showed almost complete coverage of root surface by hPLF with time. At 24 h of cell culture, the largest area of coverage was seen in the samples treated with CA10-90 (98 ± 0.89 %) at 24 h of cell culture and this difference was significant (p < 0.05) in comparison to CA10-180 (84.04 ± 5.01 %), CA50-90 (63.28 ± 12.46 %), CA50-180 (56.59 ± 8.76 %) and C (0.06 ± 0.11 %). In all the other comparisons, there was no statistically significant differences between CA10 and CA50 (p > 0.05). Cells grown on surfaces treated with CA10 were more spread and flatten than in the CA50 specimens.

CONCLUSIONS

Periodontally compromised roots surfaces conditioned with 10 % citric acid for 90 s resulted in better substrate for hPLF proliferation, in initial periods of culture than 50 % citric acid. The enlargement of the dentinal tubules did not seem to be influenced by the acid concentration.

Structure and properties of two glucose-based deep eutectic systems

Continued industrialization and increasing environmental problems have highlighted the need to research new eco-friendly solvents, also known as deep eutectic solvents (DESs). To implement these solvents in industrial processes, the knowledge of their molecular organization and thermophysical properties must be enhanced. In this work, two DESs have been characterized: d-glucose:choline chloride:water (GCH) and d-glucose:citric acid:water (GCiH). NMR techniques were used to analyse both the supramolecular structure and the role of water and to calculate the diffusion coefficients. Moreover, seven thermophysical properties at several temperatures were evaluated. As a second aim, the solubility of quercetin was determined. NMR studies showed a stronger supramolecular structure of GCH and a high ratio of β-glucose in both DESs. Based on the thermophysical results, the solvent with choline chloride had the most compact fluid structure. Finally, the solubility of quercetin in the DESs was higher than in water, especially for GCH.

Citric acid modified granular activated carbon for enhanced defluoridation

Excess fluoride (F^-, >1.5 mg F^-/L) in drinking water affects >260 million people across the globe and leads to dental and skeletal fluorosis. In this study, commercially available granular activated carbon (GAC) was modified with 0.3 M citric acid to get citric acid modified GAC (CAGAC). Over 70% of fluoride was removed in the first 60 min by CAGAC, whereas unmodified GAC removed only 30%. There were negligible interferences by co-existing ions (NO₃^-, Cl^-, HCO₃^-, SO₄^2-_, PO₄^3-) and organic matters. Maximum adsorption capacity of CAGAC was two times (1.65 mg/g) that of unmodified GAC (0.88 mg/g). Dubinin-Radushkevich (D-R) isotherm described the experimental data well indicating that ion exchange was involved in fluoride removal. CAGAC worked effectively over a wide range of pH (2-10) even though the point-of-zero-charge (PZC) was 4.89, and so the removal was not controlled by electrostatic interaction alone; surface adsorption and intra-particle diffusion were the rate-determining processes.