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1.
Mar Pollut Bull ; 159: 111480, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32738639

RESUMO

Batch experiments were conducted to study the migration behavior of arsenic (As) and iron (bivalent, trivalent, and total Fe) of the presence of the low molecular weight organic acids (LMWOAs) citric acid, malic acid, and oxalic acid in As-enriched mangrove sediments. The results for supernatant As/Fe species were significant according to each LMWOA treatment. Significant non-linear correlations were found among As level, pH, and acid dose based on our predictive model. The capacity of LMWOAs to mobilize As/Fe species followed the order of citric acid > malic acid/oxalic acid. The supernatant As correlated positively with the LMWOAs dose and negatively correlated with the pH. As migration was affected by acid strength, the number of carboxyl groups, the pH and levels of Fe compounds in the sediments. The results indicate that LMWOAs can potentially attenuate As contamination from mangrove sediment, allowing for a better understanding of As/Fe behavior in the rhizosphere.


Assuntos
Arsênico , Disponibilidade Biológica , Concentração de Íons de Hidrogênio , Peso Molecular , Compostos Orgânicos , Ácido Oxálico
2.
J Environ Sci (China) ; 96: 85-92, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32819702

RESUMO

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.


Assuntos
Poluentes do Solo/análise , Ácido Cítrico , Metais , Ácido Oxálico , Espectroscopia de Infravermelho com Transformada de Fourier
3.
Environ Pollut ; 265(Pt A): 115013, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32593073

RESUMO

Based on the goal of green and effective removal of chromium (Cr(VI)) pollution in water and the idea of treating waste with waste, rice straw (RS) was firstly and successfully used in enhancing the photoreduction of highly toxic Cr(VI) to less toxic Cr(III) by oxalic acid (Ox). Batch experiments (the effect of Ox concentration, initial Cr(VI) concentration, RS dosage and coexisting ions) in Ox + RS + UV photoreduction system were designed to investigate the reaction process. Through studying the effect of initial pH in the solution, the change of pH during the photoreduction process and the free radical scavenging test, the Cr(VI) photoreduction mechanism in Ox + RS + UV system was revealed. The role of RS in Ox + RS + UV system was also deduced by the analysis of FT-IR, XRD, Mott-Schottky and the verification test of the role of -OH and SiO2 on RS. The results showed that RS could significantly synergize Ox to reduce Cr(VI) under UV, 1 mM Cr(VI) in aqueous solution was completely removed in 60 min by Ox + RS + UV system. The Cr(VI) photoreduction mechanism in Ox + RS + UV system consisted of multiple parts: the chemical reduction by Ox(few part), the photoreduction by Ox(some part), and the synergistic photoreduction by RS with Ox(large part). The synergism of RS in Ox + RS + UV system was mainly attributed to its components of SiO2 and -OH of cellulose.


Assuntos
Oryza , Poluentes Químicos da Água/análise , Adsorção , Cromo , Concentração de Íons de Hidrogênio , Ácido Oxálico , Dióxido de Silício , Espectroscopia de Infravermelho com Transformada de Fourier
4.
Ecotoxicol Environ Saf ; 201: 110873, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32544750

RESUMO

Batch experiments were conducted to examine the differential effects of biochar pyrolysis temperature and low-molecular-weight organic acids on the reduction of As(V) and Cr(VI) driven by Pennisetum hydridum biochar. The results showed that pyrolysis temperature significantly affected the reducing strength of the biochar. Biochar produced at 500 °C had a stronger electron-donating capacity than did the biochars produced at 300 and 700 °C. In the co-presence of the biochar and a low-molecular-weight organic acid, arsenic and chromium behaved differently. Oxalic acid and malic acid tended to have better effects on enhancing biochar-driven Cr(VI) reduction, as compared to citric acid while the opposite was observed for biochar-driven As(V) reduction. Biochar produced at 300 °C was more favourable for Cr(VI) reduction, as compared to the higher-temperature biochars while the opposite was observed for As(V) reduction in the presence of low-molecular-weight organic acids. This may make the lower-temperature biochar ideal for remediating contaminated soils containing both As(V) and Cr(VI) since it could maximize Cr(VI) reduction while minimizing As(V) reduction.


Assuntos
Arseniatos/metabolismo , Carvão Vegetal/química , Cromo/metabolismo , Poluentes do Solo/metabolismo , Biodegradação Ambiental , Ácido Cítrico/química , Malatos/química , Peso Molecular , Ácido Oxálico/química , Pirólise , Temperatura
5.
Environ Sci Pollut Res Int ; 27(28): 35580-35590, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32594435

RESUMO

The desorption of radioactive cesium (Cs) in soil is influenced by the clay mineral type, adsorption site, and concentration of Cs. In this study, experiments to detect desorption of non-radioactive and radioactive Cs from illite using oxalic acid were performed for 2 days at 70 °C in hydrothermal conditions. The results showed that the 133Cs removal efficiency by oxalic acid and inorganic acid treatment was similar at high concentration (22.86 mmol/kg) of non-radioactive 133Cs. In the radioactive 137Cs experiment, the removal efficiency by oxalic acid was higher than that by inorganic acid at low concentration (0.79 × 10-6 mmol/kg) of radioactive 137Cs. Based on the illite hypothetical frayed edge site (FES) concentration of 0.612 mmol/kg, the results suggested that 137Cs was preferentially adsorbed to FES on illite. The 137Cs at low concentration was difficult to remove because it was irreversible adsorption to FES, while the non-radioactive Cs at high concentration was mainly adsorbed to planar sites, and so was easy to desorb by ion exchange. Based on the results of NMR, FTIR, and XPS analyses, we concluded that the higher efficiency of 137Cs removal at low concentration by oxalic acid treatment than by treatment with inorganic acid was because of chelation effects associated with the complexation of oxalic acid (ligands) and metal ions in irreversible site (FES).


Assuntos
Ácido Oxálico , Poluentes Radioativos da Água/análise , Adsorção , Césio , Minerais
6.
Environ Sci Pollut Res Int ; 27(21): 26115-26124, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32358750

RESUMO

Goethite is an effective adsorbent for hexavalent chromium (Cr(VI)). Oxalic acid and other organic acids will affect the release, immobilization, and bioavailability of Cr(VI) in nature on the mineral surface. Mn(II) can accelerate the reduction of Cr(VI) with oxalic acid. Herein, the effects of oxalic acid and Mn(II) on the mobilization and transformation of adsorbed Cr(VI) on the surface of goethite were investigated in this study. The results revealed that Mn(II) could increase the adsorption of Cr(VI) by increasing the positive charge on the surface of goethite. The complexation of oxalic acid with the surface of goethite caused the adsorbed Cr(VI) to be released into the solution. Moreover, oxalic acid could undergo redox with adsorbed Cr(VI) through electron conduction on the surface of goethite, thereby resulting in the transformation of adsorbed Cr(VI) to Cr(III). During the reaction in the presence of oxalic acid, the concentration of Cr(III) increased from 0 to 13.9 mg/L. In addition, Mn(II), oxalic acid, and Cr(VI) could form unstable ester-like species in the solution, which accelerated the reduction of Cr(VI) to Cr(III). These findings of this study may enrich our understanding of the behaviors of Cr(VI) in the coexistence of goethite, oxalic acid, and Mn(II).


Assuntos
Compostos de Ferro , Ácido Oxálico , Adsorção , Cromo , Concentração de Íons de Hidrogênio , Minerais , Oxirredução
7.
Chemosphere ; 255: 126950, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32380266

RESUMO

Metal-modified carbon materials have been widely used for fluoride removal, but the traditional impregnation by soaking method suffers from low loading of metals and substantial use of chemicals. This study proposed a new approach to prepare zirconium modified activated carbon fibres (Zr-ACF) by a drop-coating method. Using the same amount of chemicals, the drop-coating method yielded a 5.5 times higher fluoride adsorption capacity than the soaking method due to more effective loading of Zr(IV) onto ACF. The effects of various preparation conditions, including the addition of a complexing agent (oxalic acid) and Zr/ACF mass ratio (0.2-1), were investigated. Zr-ACF prepared by drop-coating was characterised by SEM and BET, and the functional groups involved in the anchoring of Zr(IV) on ACF and the adsorption of fluoride onto Zr-ACF were identified by FTIR and XPS. Adsorption experiments at pH between 3 and 11 revealed that ion exchange and electrostatic attraction were the main adsorption mechanisms at different pH levels. Co-existing anions such as CO32-, HCO3- and Cl- had an insignificant negative impact (<5%) on fluoride adsorption capacity while SO42- decreased fluoride adsorption capacity by 11.5%. The adsorption kinetics followed the pseudo-second-order model. The adsorption isotherms followed the Langmuir isotherm model with a maximum fluoride adsorption capacity of 28.50 mg/L at 25 °C, which was higher than other carbon-based materials in the literature. The remarkable improvement of adsorption capacity and reduced chemical consumption demonstrate that Zr-ACF prepared by drop-coating is a promising adsorbent for fluoride removal.


Assuntos
Fluoretos/química , Poluentes Químicos da Água/química , Zircônio/química , Adsorção , Ânions , Fibra de Carbono , Carvão Vegetal , Concentração de Íons de Hidrogênio , Troca Iônica , Cinética , Ácido Oxálico , Água , Purificação da Água/métodos
8.
J Contemp Dent Pract ; 21(2): 119-123, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-32381813

RESUMO

AIM: The aim of this study is to compare the efficacy of dipotassium oxalate and potassium nitrate to occlude dentinal tubules. MATERIALS AND METHODS: This study utilized Parkinson model of longitudinal dentin tubule occluding properties of dentifrices under a 4-day acid challenge. Dentin disks of approximately 1.5 mm thick were sectioned from the crowns of the freshly extracted molars. The disks were randomized into three sets of 15 and treated with dipotassium oxalate, potassium nitrate, or used as a control. The disks were then subjected to a 4-day acid challenge and evaluated by scanning electron microscopy (SEM). RESULTS: On days 1, 2, and 3, dipotassium oxalate showed significant occlusion of dentinal tubules. On day 4, no significant difference was observed between dipotassium oxalate and potassium nitrate. Both test groups showed better occlusion properties in comparison to the control. CONCLUSION: Through the use of a 4-day acid challenge, this study demonstrates that both agents can indeed occlude dentinal tubules. Initially, dipotassium oxalate does occlude dentinal tubules faster than potassium nitrate. However, at the conclusion of the acid challenge, minimal differences were observed in occlusion rate among the two agents. Further studies should be conducted to determine the efficacy of these two agents. CLINICAL SIGNIFICANCE: Both dipotassium oxalate and potassium nitrate can help treat patients with dentinal hypersensitivity.


Assuntos
Permeabilidade da Dentina , Ácido Oxálico , Dentina , Humanos , Nitratos , Compostos de Potássio
9.
J Environ Manage ; 268: 110678, 2020 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-32383648

RESUMO

The 4-chlorophenol (4-CP) is known to be a highly toxic compound having harmful effects on human health and the environment. Due to adverse effect of 4-CP, a new combination of persulfate (PS) and oxalic acid (OA) with heterogeneous Fenton like (HFL) system was developed and applied for 4-CP degradation as an emerging contaminant from synthetic wastewater. The individual (OA, PS, and HFL) and combined (HFL/OA, HFL/PS, and HFL/OA/PS) systems were investigated under various conditions to synergistic effects verification and determination of degradation mechanism of 4-CP. Compared to individual and combined systems, significant synergetic of 4-CP degradation efficiency was observed by HFL/OA/PS system. The highest 4-CP degradation efficiency by HFL/OA/PS system under optimal conditions (solution pH: 6, H2O2 dose: 275 mg/L, goethite dose: 125 mg/L, OA dose: 50 mg/L and PS dose: 100 mg/L) with an initial 4-CP concentration of 30 mg/L was 99.6 ± 4.9% after 35 min reaction time. 4-CP degradation by HFL/OA/PS system was followed with the first-order kinetic. The application of radical scavengers including ethanol (EtOH) and tert-butyl alcohol (TBA) revealed that the SO4•- radical was determined as primary produced radical species. The Cl- ions release was measured during degradation reaction at various 4-CP concentrations and indicating the complete 4-CP degradation. The developing of the adaptive neuro-fuzzy inference system (ANFIS) for 4-CP degradation efficiency prediction was revealed. These results show that prediction of 4-CP degradation efficiency using HFL/OA/PS system is possible by the ANFIS model with a high accuracy (R2: 0.98).


Assuntos
Águas Residuárias , Poluentes Químicos da Água , Clorofenóis , Peróxido de Hidrogênio , Ácido Oxálico , Oxirredução
10.
Chemosphere ; 253: 126731, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32302907

RESUMO

Bioremediation of Cr(VI) contamination using microorganisms is a promising method for reducing its environmental risks. The objective of this study was to clarify Cr(VI) removal by Penicillium oxalicum SL2 in terms of indirect Cr(VI) reduction by metabolites, interaction sites, and form transformation of chromium. Strain SL2 could sequentially remove Cr(VI) in the bioreactor. Oxalic acid produced by the fungus contributed to Cr(VI) reduction. Scanning transmissiony X-ray microscop (STXM) analysis suggested strain SL2 could partly reduce Cr(VI) to Cr(III) in the cell. Amine, carboxyl, and phosphate groups were related to Cr(VI) removal. Chromium K-edge X-ray absorption near edge structure (XANES) analysis implied Cr(III)-Cys potentially acted as an intermediate for the formation of chromium oxalate complexes during the process of treatment. This study would support the application of strain SL2 in Cr(VI) bioremediation and expand knowledge on the interaction of chromium with fungus.


Assuntos
Reatores Biológicos/microbiologia , Cromo/análise , Poluentes Ambientais/análise , Micélio/metabolismo , Ácido Oxálico/análise , Penicillium/metabolismo , Biodegradação Ambiental , Cromo/metabolismo , Poluentes Ambientais/metabolismo , Ácido Oxálico/metabolismo , Oxirredução , Fosfatos/análise
11.
Food Chem ; 318: 126479, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32135423

RESUMO

In this study, we prepared waxy maize starch nanocrystals (SNCs) for the first time using dry-heated oxalic acid hydrolysis with or without ultrasonic treatment. The dry-heating treatment was subjected to oxalic acid hydrolysis to produce SNCs with a high yield of 89.6%. Dynamic light scattering showed that the size of the obtained SNCs was 46.58-197.15 nm, and the polydispersion index was 0.28-0.52. Atomic force microscopy investigation found that the SNCs had a major axis of about 211.5 nm and a height of about 9.4 nm. The thermogravimetric analysis revealed that the SNCs' thermal stability slightly improved compared with that of native starch. X-ray diffraction indicated that the produced SNCs preserved the A-type crystal form of native starch, with the relative crystallinities of 29.52%-42.44%. The newly fabricated SNCs have potential applications in agriculture, cosmetics, and advanced materials.


Assuntos
Nanopartículas/química , Amido/química , Zea mays/química , Difusão Dinâmica da Luz , Hidrólise , Microscopia de Força Atômica , Microscopia Eletrônica de Transmissão , Ácido Oxálico/química , Tamanho da Partícula , Espectroscopia de Infravermelho com Transformada de Fourier , Termogravimetria , Ultrassom , Difração de Raios X
12.
Phytopathology ; 110(7): 1319-1325, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32154765

RESUMO

Poplar Cytospora canker, which is mainly caused by Cytospora chrysosperma, is one of the most destructive and widespread tree diseases worldwide. Although oxalic acid (OA) is demonstrated as an important virulence determinant in several necrotrophic fungi, specific functions of OA during pathogenesis remain controversial. Here, we identified three genes (CcOah, CcOdc1, and CcOdc2) directly involved in OA biosynthesis and catabolism in C. chrysosperma. We demonstrated that CcOah is required for OA biogenesis. All three genes were found to be highly upregulated during early infection stages of the poplar stem. The deletion of any of the three genes led to an obvious reduction of pycnidial production but no abnormality of hyphal growth and morphology. Furthermore, the individual deletion strain exhibited significantly limited lesion sizes on poplar twigs and leaves. Exogenous application of OA or citric acid can complement the virulence defects of ΔCcOah and ΔCcOdc1 strains. We further found that the ΔCcOah strain strongly promoted reactive oxygen species burst of poplar leaves during infection. Finally, induced secretion of OA was observed by monitoring color change of the plates after poplar stem extracts were added in the cultures; however, we failed to quantify OA concentration by high-performance liquid chromatography. Taken together, the present results provide insights into the function of OA acting as an important virulence factor of C. chrysosperma.


Assuntos
Ascomicetos , Populus , Ácido Oxálico , Doenças das Plantas , Virulência
13.
Chem Commun (Camb) ; 56(18): 2775-2778, 2020 Mar 03.
Artigo em Inglês | MEDLINE | ID: mdl-32022095

RESUMO

The expeditious construction of phenanthridine scaffolds via a Pd/MnO2-mediated C-H arylation/oxidative annulation cascade involving aldehydes, aryl iodides and amino acids is disclosed. This reaction proceeds smoothly involving the formation of multiple chemical bonds with the tolerance of a wide range of functional groups. The control experiments suggest a radical mechanism for C-N bond formation via MnO2-promoted oxidative annulation of imine compounds. The synthetic utility of this transformation has been demonstrated via the straightforward access to bioactive natural alkaloid trisphaeridine and its analogue.


Assuntos
Aldeídos/química , Aminoácidos/química , Hidrocarbonetos Iodados/química , Ácido Oxálico/química , Paládio/química , Fenantridinas/síntese química , Estrutura Molecular , Oxirredução , Fenantridinas/química
14.
J Econ Entomol ; 113(2): 582-588, 2020 04 06.
Artigo em Inglês | MEDLINE | ID: mdl-31909423

RESUMO

A successful Integrated Pest Management approach to Varroa destructor Anderson and Trueman control in managed colonies of western honey bees Apis mellifera Linnaeus (Hymenoptera: Apidae) must be an improvement over conventional control methods and include cost-effective treatments that can be readily employed by beekeepers. Herein, we tested the efficacy of oxalic acid (OA) vaporization and brood interruption as Varroa controls. Sixty experimental colonies were randomly assigned to one of six treatment groups with 10 colonies per group. The six treatments were: 1) OA applied once, 2) OA applied three times, 3) brood interruption, 4) OA applied once + brood interruption, 5) OA applied three times + brood interruption, and 6) no OA or brood interruption. The OA was applied via vaporization, with each application being 1 g OA applied through the hive entrance (label rate), on the bottom board. Brood interruption was accomplished by caging a colony's queen in a queen cage for a period of 24 d. An additional 10 colonies were treated with amitraz (Apivar - positive control). Varroa levels were estimated before, during, and after treatment applications using sticky boards left in colonies for 3 d. Our data suggest that queen caging to achieve brood interruption during the fall season can negatively impact colony strength and survival. We observed high colony mortality in some treatments, despite diligent colony management to alleviate the side effects of the treatments. Colonies treated with amitraz were healthier and had better survival than those treated with OA vaporization. In conclusion, OA and/or brood interruption did not provide sufficient Varroa control.


Assuntos
Ácaros e Carrapatos , Varroidae , Animais , Abelhas , Ácido Oxálico , Controle de Pragas , Volatilização
15.
J Chromatogr A ; 1617: 460832, 2020 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-31928771

RESUMO

This paper demonstrated a simple and rapid approach for the determination of lead dioxide in minium using a headspace gas chromatographic (GC) technique. This new approach was based on the measurement of carbon dioxide from the redox reaction between lead dioxide and oxalic acid in a sealed headspace vial. The obtained results indicated that the new approach had good measurement accuracy (relative errors ≤8.71%) and precision (RSD ≤2.86%). Moreover, the limit of quantification (LOQ) and limit of detection (LOD) for this new approach were respectively 0.34% and 0.10%, and the recoveries ranged from 97.9 to 101.7%. The new approach is low-cost and reliable, which has potential for use in the analysis of lead dioxide in minium and related products.


Assuntos
Cromatografia Gasosa/métodos , Chumbo/análise , Óxidos/análise , Dióxido de Carbono/análise , Chumbo/química , Limite de Detecção , Ácido Oxálico/química , Oxirredução , Óxidos/química
16.
Food Chem ; 312: 126051, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-31891888

RESUMO

Post-cut surface browning is one of the major constraints for shelf-life extension of lotus root slices. In the present study, lotus roots slices were treated with 0, 5 and 10 mmol L-1 oxalic acid and stored at 20 ± 1 °C for 5 days. Results showed that 10 mmol L-1 oxalic acid treated lotus slices exhibited reduced browning, superoxide anion, hydrogen peroxide, electrolyte leakage and malondialdehyde content than control. The 10 mmol L-1 treated slices had better visual quality and higher ascorbic acid and total phenolic contents. In addition, 10 mmol L-1 treated slices showed reduced total bacterial count along with lower soluble quinones, peroxidase and polyphenol oxidase activities in contrast to control. Similarly, 10 mmol L-1 treatment showed higher superoxide dismutase, catalase and ascorbate peroxidase activities as compared to control. In conclusion, 10 mmol L-1 oxalic acid application could be considered suitable to delay post-cut browning of lotus root slices.


Assuntos
Lotus/efeitos dos fármacos , Nelumbo/efeitos dos fármacos , Ácido Oxálico/farmacologia , Catalase/metabolismo , Cor , Lotus/metabolismo , Nelumbo/metabolismo , Oxirredução , Peroxidase/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo
17.
Int J Mol Med ; 45(2): 375-384, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31894301

RESUMO

MicroRNAs (miRNAs or miRs) are critical regulators in various diseases. In the current study, the role of miR­30c­5p in the formation of sodium oxalate­induced kidney stones was investigated. For this purpose, human renal tubular epithelial cells (HK­2 cells) were incubated with sodium oxalate at the concentrations of 100, 250, 500, 750 and 1,000 µM. Cell viability and the miR­30c­5p expression level were respectively measured by CCK­8 assay and RT­qPCR. After separately transfecting miR­30c­5p mimic and inhibitor into the HK­2 cells, the cell apoptotic rate, the levels of mitochondrial membrane potential (MMP) and ROS were determined by flow cytometry. The levels of oxidative stress indicators [lactate dehydrogenase (LDH), malondialdehyde (MDA), superoxide dismutase (SOD) and catalase (CAT)] were determined using commercial kits. Crystal­cell adhesion assay was performed to evaluate the crystal adhesion capacity in vitro. miR­30c­5p binding at autophagy related 5 (ATG5) was predicted by TargetScan7.2 and further verified by dual­luciferase reporter assay. Rescue experiments were performed to confirm the molecular mechanisms underlying sodium oxalate­induced kidney formation in HK­2 cells. The results revealed that sodium oxalate decreased the viability of HK­2 cells in a concentration­dependent manner, and that miR­30c­5p expression was significantly downregulated by exposure to 750 µM sodium oxalate. In addition, the increase in cell apoptosis and crystal number, and the upregulated levels of LDH, MDA and ROS were reversed by the overexpression of miR­30c­5p. Moreover, the overexpression of miR­30c­5p upregulated the levels of SOD, CAT and MMP induced by sodium oxalate. ATG5 was directly regulated by miR­30c­5p, and the inhibition of cell cytotoxicity and crystal­cell adhesion induced by miR­30c­5p mimic was blocked by ATG5. These data indicated that the overexpression of miR­30c­5p alleviated cell cytotoxicity and crystal­cell adhesion induced by sodium oxalate through ATG5. Thus, the current study provides a better understanding of the role of miR­30c­5p in sodium oxalate­induced kidney stones.


Assuntos
Proteína 5 Relacionada à Autofagia/genética , Cálculos Renais/genética , MicroRNAs/genética , Regulação para Cima , Apoptose , Proteína 5 Relacionada à Autofagia/metabolismo , Linhagem Celular , Regulação da Expressão Gênica , Humanos , Rim/metabolismo , Rim/patologia , Cálculos Renais/metabolismo , Cálculos Renais/patologia , Ácido Oxálico/metabolismo , Estresse Oxidativo
18.
Chemosphere ; 243: 125414, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31783184

RESUMO

Root-induced changes play a crucial role in influencing the fate and speciation of potentially toxic elements (PTEs) in contaminated soils, but their role in the phytostabilization of waste slag sites remain unclear. The aim of this study was to determine the effect of four phytostabilization plants, Broussonetia papyrifera, Arundo donax, Robinia pseudoacacia, and Cryptomeria fortunei, planted in a zinc smelting waste slag site for 5 years on PTEs speciation and the mineral and aggregation characteristics at the interface of the waste slag-plant system. The results showed that the presence of a higher content of oxalic acid in the rhizosphere slags of the four plant species than in the bare slag. Revegetation of the waste slag with the four plant species significantly changed the mineral composition and morphology of the waste slag. The mass percentage of large particles (1-5 mm) and small particles (0.5-1 mm, 0.25-0.5 mm, and <0.25 mm) in the rhizosphere slags decreased and increased, respectively. The PTEs (Cu, Pb, Zn, and Cd) in most of the rhizosphere slags were mainly distributed within the small particles, and the enrichment coefficients of PTEs in the large particles and small particles were less than and greater than 1, respectively. The bioavailability of the PTEs in the waste slag increased with decreasing particle size. Root-induced the transformation of acid-soluble PTEs into their reducible, oxidizable, and residual forms in the different waste slag particles weathered in the rhizosphere. These results suggested that there are root-induced changes in the aggregation characteristics and geochemical behaviours of PTEs in waste slag fractions during the phytoremediation of waste slag sites.


Assuntos
Biodegradação Ambiental , Rizosfera , Poluentes do Solo/análise , Zinco/análise , Elementos , Metais Pesados/análise , Metais Pesados/metabolismo , Ácido Oxálico/análise , Tamanho da Partícula , Raízes de Plantas/metabolismo , Poaceae/química , Poaceae/metabolismo
19.
Environ Technol ; 41(4): 430-439, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30010507

RESUMO

In this study, the enhanced effect of oxalic acid (Ox) on Cr(VI) electroreduction was evaluated. It was found that for Cr(VI)-contaminated solution ([Cr(VI)]0 = 1.0 mM, pH = 3.0), addition of 5.0 mM Ox can significantly increase Cr(VI) reduction from 0.36 to 1.0 mM within 90 min electrolysis reaction, accompanying with the increase of current efficiency from 19% to 53%. Increasing initial Ox concentration (0-10 mM) and electric current (10-40 mA) facilitated Cr(VI) reduction, whereas it was inhibited with decreasing solution pH value (2.0-3.5) and elevating Cr(VI) concentration (0.1-2.0 mM), respectively. Results show that reactive electron was the primary reductant for the heterogeneous reduction of Cr(VI) on the cathode. In addition, Ox can also serve as an electron donor for the homogeneous reduction of Cr(VI). During this process, the formation of Cr(VI)-oxalate complex is indispensable for the enhanced Cr(VI) reduction. The coordination of Ox with Cr(VI) did not only make the structure of Cr(VI) more distorted but also improved the reactivity of Cr(VI) in Cr(VI)-oxalate complex toward reduction reaction. In general, this study provides an energy-efficient and environmentally benign strategy for the treatment of Ox and Cr(VI) co-contaminated wastewater.


Assuntos
Cromo , Ácido Oxálico , Concentração de Íons de Hidrogênio , Oxirredução , Águas Residuárias
20.
Chemosphere ; 241: 125025, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31604190

RESUMO

Metals in atmospheric aerosols play potentially an important role in human health and ocean primary productivity. However, the lack of knowledge about solubility and speciation of metal ions in the particles or after solubilisation in aqueous media (sea or surface waters, cloud or rain droplets, biological fluids) limits our understanding of the underlying physico-chemical processes. In this work, a wide range of metals, their soluble fractions, and inorganic/organic compounds contained in urban particulate matter (PM) from Padua (Italy) were determined. Metal solubility tests have been performed by dissolving the PM in water and in solutions simulating rain droplet composition. The water-soluble fractions of the metal ions and of the organic compounds having ligand properties have been subjected to a multivariate statistical procedure, in order to elucidate associations among the aqueous concentrations of these PM components in simulated rain droplets. In parallel, a multi-dimensional speciation calculation has been performed to identify the stoichiometry and the amount of metal-ligand complexes theoretically expected in aqueous solutions. Both approaches showed that the solubility and the aqueous speciation of metal ions were differently affected by the presence of inorganic and organic ligands in the PM. The solubility of Al, Cr, and Fe was strongly correlated to the concentrations of oxalic acid, as their oxalate complexes represented the expected dominant species in aqueous solutions. Oxalates of Al represented ∼98% of soluble Al, while oxalates of Cu represented 34-75% of the soluble Cu, and oxalates of Fe represented 76% of soluble Fe. The oxidation state of Fe can strongly impact the speciation picture. If Fe is present as Fe(II) rather than Fe(III), the amount of Cr and Cu complexed with diacids can increase from 75% to 94%, and from 32% to 53%, respectively. For other metals, the solubility depended on the formation of soluble aquo-complexes, hence with a scarce effect of the organic ligands. An iron-oxalate complex was also directly detected in aerosol sample extracts.


Assuntos
Complexos de Coordenação/química , Metais/química , Ácido Oxálico/química , Material Particulado/análise , Aerossóis/análise , Humanos , Itália , Ligantes , Oxirredução , Solubilidade , Reforma Urbana , Água
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