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1.
Molecules ; 25(16)2020 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-32824192

RESUMO

The use of renewable local raw materials to produce fuels is an important step toward optimal environmentally friendly energy consumption. In addition, the use of these sources together with fossil fuels paves the way to an easier transition from fossil to renewable fuels. The use of simple organic acids as hydrogen donors is another alternative way to produce fuel. The present work reports the use of oxalic acid as a hydrogen donor for the catalytic hydrodesulfurization of atmospheric gas oil and the deoxygenation of rapeseed oil at 350 °C. For this process, one commercial NiW/SiO2-Al2O3 solid and two NiW/modified phonolite catalysts were used, namely Ni (5%) W (10%)/phonolite treated with HCl, and Ni (5%) W (10%)/phonolite treated with oxalic acid. The fresh phonolite catalysts were characterized by Hg porosimetry and N2 physisorption, ammonia temperature programmed desorption (NH3-TPD), X-ray diffraction (XRD), and X-ray fluorescence (XRF). The sulfided metal phonolite catalysts were characterized by XRD and XRF. Hydrodesulfurization led to a decrease in sulfur content from 1 to 0.5 wt% for the phonolite catalysts and to 0.8 wt% when the commercial catalyst was used. Deoxygenation led to the production of 15 and 65 wt% paraffin for phonolite and commercial solids, respectively. The results demonstrate the potential of using oxalic acid as a hydrogen donor in hydrotreating reactions.


Assuntos
Gasolina/análise , Hidrogênio/química , Ácido Oxálico/química , Oxigênio/química , Óleo de Brassica napus/química , Enxofre/isolamento & purificação , Catálise , Campos de Petróleo e Gás , Enxofre/química
2.
Sci Rep ; 10(1): 3595, 2020 02 27.
Artigo em Inglês | MEDLINE | ID: mdl-32108167

RESUMO

A natural low-methoxyl pectin (LAHP), was extracted with oxalic acid solution from dried heads of sunflower (Helianthus annuus L.). The single-factor experiments and response surface methodology (RSM) were used to optimize LAHP extraction conditions. The extraction yield of LAHP was 18.83 ± 0.21%, and the uronic acid content was 85.43 ± 2.9% obtained under the optimized conditions (temperature of 96 °C, time of 1.64 h, oxalic acid concentration of 0.21%). Experimentally obtained values were in agreement with those predicted by RSM model, indicating suitability of the employed model and the success of RSM in optimizing the extraction conditions. LAHP has been characterized by ash content, degree of esterification (DE), galacturonic acid (GalA) content, molecular weight and intrinsic viscosity meanwhile commercial low-methoxyl pectin (CLMP) as comparison. This study finds out a potential source of natural LMP which expands the application scope of sunflower heads. It is an efficient reuse of waste resources and provides a novel thought to explore the natural resources for food and pharmaceutical applications.


Assuntos
Produtos Biológicos/uso terapêutico , Indústria Alimentícia/métodos , Gastroenteropatias/terapia , Helianthus/fisiologia , Hipertensão/terapia , Neoplasias/terapia , Pectinas/química , Extratos Vegetais/uso terapêutico , Cosméticos , Flores , Humanos , Modelos Estatísticos , Ácido Oxálico/química , Extratos Vegetais/química
3.
Int J Biol Macromol ; 148: 41-48, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31917981

RESUMO

We obtained a new acidic soy hull polysaccharide (SHP-1) with a molecular weight (Mw) of 4.81 × 105 g/mol through ammonium oxalate and microwave assisted extraction. SHP-1 was mainly composed of galacturonic acid, galactose, rhamnose and arabinose (molar ratio = 46.59%:17.95%:14.77%:13.97%) with small amounts of fucose, glucose, mannose and xylose. The chemical structure was presumed to be of pectin-I type, consisting of 2/3 HGA and 1/3 RG-I. Furthermore, the rheological information and the chain morphology of SHP-1 were different in five solvents. Surfactant, salt and alkali solutions enhanced the solubility and flexibility of the polysaccharide, but the polysaccharide showed decreased fluidity under acidic conditions. The addition of ions and alkali increased the consistency coefficient of the solution, but the effect was far less than that of the cross-linking morphology. The structural and morphological information of purified SHP should aid in further study of its structure-function relationships and applications.


Assuntos
Glycine max/química , Conformação Molecular , Pectinas/química , Polissacarídeos/química , Arabinose/análise , Cromatografia em Gel , Galactose/análise , Ácidos Hexurônicos/análise , Micro-Ondas , Peso Molecular , Ácido Oxálico/química , Pectinas/isolamento & purificação , Polissacarídeos/isolamento & purificação , Ramnose/análise , Reologia , Solubilidade
4.
Sci Rep ; 9(1): 19817, 2019 12 24.
Artigo em Inglês | MEDLINE | ID: mdl-31875012

RESUMO

This study investigated the effect of ethylenediamine-N,N'-disuccinic acid (EDDS), oxalic acid (OA), and citric acid (CA) on phytoextraction of U- and Cd-contaminated soil by Z. pendula. In this study, the biomass of tested plant inhibited significantly following treatment with the high concentration (7.5 mmol·kg-1) EDDS treatment. Maximum U and Cd concentration in the single plant was observed with the 5 mmol·kg-1 CA and 7.5 mmol·kg-1 EDDS treatment, respectively, whereas OA treatments had the lowest U and Cd uptake. The translocation factors of U and Cd reached the maximum in the 5 mmol·kg-1 EDDS. The maximum bioaccumulation of U and Cd in the single plants was 1032.14 µg and 816.87 µg following treatment with 5 mmol·kg-1 CA treatment, which was 6.60- and 1.72-fold of the control groups, respectively. Furthermore, the resultant rank order for available U and Cd content in the soil was CA > EDDS > OA (U) and EDDS > CA > OA (Cd). These results suggested that CA could greater improve the capacity of phytoextraction using Z. pendula in U- and Cd- contaminated soils.


Assuntos
Biodegradação Ambiental , Quelantes/química , Gastrópodes/fisiologia , Poluentes do Solo/análise , Solo/química , Animais , Biomassa , Cádmio/química , Ácido Cítrico/química , Etilenodiaminas/química , Concentração de Íons de Hidrogênio , Ácido Oxálico/química , Succinatos/química , Urânio/química
5.
Anal Chim Acta ; 1052: 57-64, 2019 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-30685042

RESUMO

The geochemical fate of indium in natural waters is still poorly understood, while recent studies have pointed out a growing input of this trivalent element in the environment as a result of its utilisation in the manufacturing of high-technology products. Reliable and easy-handling analytical tools for indium speciation analysis are, then, required. In this work, we report the possibility of measuring the total and free indium concentrations in solution using two complementary electroanalytical techniques, SCP (Stripping chronopotentiometry) and AGNES (Absence of Gradients and Nernstian Equilibrium Stripping) implemented with the TMF/RDE (Thin Mercury Film/Rotating Disk Electrode). Nanomolar limits of detection, i.e. 0.5 nM for SCP and 0.1 nM for AGNES, were obtained for both techniques in the experimental conditions used in this work and can be further improved enduring longer experiment times. We also verified that AGNES was able (i) to provide robust speciation data with the known In-oxalate systems and (ii) to elaborate indium binding isotherms in presence of humic acids extending over 4 decades of free indium concentrations. The development of electroanalytical techniques for indium speciation opens up new routes for using indium as a potential tracer for biogeochemical processes of trivalent elements in aquifers, e.g. metal binding to colloidal phases, adsorption onto (bio)surfaces, etc.


Assuntos
Eletroquímica/métodos , Índio/química , Adsorção , Eletroquímica/instrumentação , Eletrodos , Substâncias Húmicas/análise , Ácido Oxálico/química
6.
Toxicol Mech Methods ; 28(3): 195-204, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28980857

RESUMO

Experimental induction of hyperoxaluria by ethylene glycol (EG) administration is disapproved as it causes metabolic acidosis while the oral administration of chemically synthesized potassium oxalate (KOx) diet does not mimic our natural system. Since existing models comprise limitations, this study is aimed to develop an improved model for the induction of dietary hyperoxaluria, and nephrocalcinosis in experimental rats by administration of naturally available oxalate rich diet. Male albino Wistar rats were divided into five groups. Group I, control; group II rats received 0.75% EG, group III rats fed with 5% KOx diet and group IV and V rats were administered with spinach extract of 250 and 500 mg soluble oxalate/day respectively, for 28 d. Urine and serum biochemistry were analyzed. After the experimental period, rats were sacrificed, liver and kidney tissue homogenates were used for antioxidant and lipid peroxidation assay. Relative change in expression of kidney injury molecule-1 (KIM-1) and crystal modulators genes in kidney tissues were evaluated. Tissue damage was assessed by histology studies of liver and kidney. Experimental group rats developed hyperoxaluria and crystalluria. Urine parameters, serum biochemistry, antioxidant profile, lipid peroxidation levels and gene expression analysis of experimental group II and III rats reflected acute kidney damage compared to group V rats. Histopathology results showed moderate hyperplasia in liver and severe interstitial inflammation in kidneys of group II and III than group V rats. Ingestion of naturally available oxalate enriched spinach extract successfully induced dietary hyperoxaluria and nephrocalcinosis in rats with minimal kidney damage.


Assuntos
Modelos Animais de Doenças , Doenças Transmitidas por Alimentos/etiologia , Hiperoxalúria/etiologia , Nefrocalcinose/etiologia , Ácido Oxálico/intoxicação , Folhas de Planta/efeitos adversos , Spinacia oleracea/efeitos adversos , Administração Oral , Animais , Biomarcadores/sangue , Biomarcadores/metabolismo , Biomarcadores/urina , Cristalização , Etilenoglicol/toxicidade , Doenças Transmitidas por Alimentos/metabolismo , Doenças Transmitidas por Alimentos/patologia , Doenças Transmitidas por Alimentos/fisiopatologia , Regulação da Expressão Gênica/efeitos dos fármacos , Hiperoxalúria/metabolismo , Hiperoxalúria/patologia , Hiperoxalúria/fisiopatologia , Rim/efeitos dos fármacos , Rim/metabolismo , Rim/patologia , Peroxidação de Lipídeos/efeitos dos fármacos , Fígado/efeitos dos fármacos , Fígado/metabolismo , Fígado/patologia , Masculino , Nefrocalcinose/metabolismo , Nefrocalcinose/patologia , Nefrocalcinose/fisiopatologia , Ácido Oxálico/administração & dosagem , Ácido Oxálico/química , Ácido Oxálico/metabolismo , Extratos Vegetais/efeitos adversos , Extratos Vegetais/química , Folhas de Planta/química , Ratos Wistar , Insuficiência Renal/etiologia , Spinacia oleracea/química
7.
J AOAC Int ; 101(4): 1183-1189, 2018 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-28935010

RESUMO

An innovative and effective digestion method based on choline chloride (ChCl)-oxalic acid (Ox) deep eutectic solvent (DES) was proposed for the determination of Se and As in fish samples via electrothermal atomic absorption spectrometry (ETAAS). The impacts of different variables, including the composition and volume of ChCl-Ox, temperature, and acid addition, on analyte recovery were studied for optimization. In this procedure, an 80 mg sample was dissolved in a 1:2 molar ratio of ChCl-Ox at 105°C for 40 min, with the subsequent addition of 4.0 mL HNO3 (1.0 M) and further heating at the same temperature for about 5 min. Next, centrifugation was applied, and the supernatant solution was filtered, diluted to a known volume, and measured by ETAAS. The accuracy of the developed method was tested using a Standard Reference Material (NIST SRM 1946 Lake Superior Fish Tissue). The proposed DES-based digestion method was successfully applied to the simultaneous extraction of Se and As from fish samples.


Assuntos
Arsênio/análise , Produtos Pesqueiros/análise , Análise de Alimentos/métodos , Selênio/análise , Solventes/química , Animais , Fracionamento Químico/métodos , Colina/química , Ácido Oxálico/química , Espectrofotometria Atômica/métodos , Temperatura , Fatores de Tempo
8.
Int J Biol Macromol ; 106: 698-703, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28818725

RESUMO

The present study was initiated to experimentally optimize the conditions for extraction using Central Composite Design. The optimum temperature and time for the extraction of pectin from Jackfruit wastes using oxalic acid were found to be 90°C and 60min respectively. The yield of pectin under these optimum conditions was 38.42%. Extraction time and temperature showed a significant (p<0.05) effect on the pectin yield. This agreed well with the experimental result of 39.05±0.59g/g of pectin, under similar conditions. Experimental studies on a large scale using 10kg of jackfruit wastes, gave a yield of 38% pectin. Pectin isolated from Jackfruit wastes can be classified as low methoxyl pectin with promising applications in low sugar products.


Assuntos
Artocarpus/química , Frutas/química , Extração Líquido-Líquido/métodos , Ácido Oxálico/química , Pectinas/isolamento & purificação , Análise Fatorial , Aditivos Alimentares/análise , Aditivos Alimentares/química , Temperatura Alta , Humanos , Pectinas/química , Fatores de Tempo , Resíduos
9.
J AOAC Int ; 101(2): 593-600, 2018 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-28821304

RESUMO

In present study, we proposed the application of a deep eutectic solvent (DES) made up of choline chloride (ChCl) and oxalic acid (Ox) for the dissolution of different edible mushroom samples for the determination of selenium (Se) and arsenic (As) ions. Therefore, an innovative, green, novel, and inexpensive method based on ChCl-Ox as the DES was developed for the determination of Se and As ions in mushroom species by graphite furnace-atomic absorption spectrometry. The important analytical parameters were also optimized. The LODs for Se and As ions were found to be 0.32 and 0.50 µg/L, respectively. The LOQs for Se and As ions were found to be 1.06 and 1.65 µg/L, respectively. The RSD was observed to be less than 5% for both analyte ions. The accuracy of the developed method was confirmed by analyzing mushroom powder Certified Reference Material CS-M-3 (Boletus edulis). The developed technique was effectively useful for the determination of Se and As ions in different species of mushroom samples from Turkey.


Assuntos
Arsênio/análise , Fracionamento Químico/métodos , Selênio/análise , Solventes/química , Agaricales/química , Colina/química , Análise de Alimentos/métodos , Química Verde/métodos , Líquidos Iônicos/química , Limite de Detecção , Ácido Oxálico/química , Espectrofotometria Atômica/métodos
10.
J Vis Exp ; (128)2017 10 05.
Artigo em Inglês | MEDLINE | ID: mdl-29053698

RESUMO

After reporting on the two-step anodization, nanoporous anodic aluminum oxides (AAOs) have been widely utilized in the versatile fields of fundamental sciences and industrial applications owing to their periodic arrangement of nanopores with relatively high aspect ratio. However, the techniques reported so far, which could be only valid for mono-surface anodization, show critical disadvantages, i.e., time-consuming as well as complicated procedures, requiring toxic chemicals, and wasting valuable natural resources. In this paper, we demonstrate a facile, efficient, and environmentally clean method to fabricate nanoporous AAOs in sulfuric and oxalic acid electrolytes, which can overcome the limitations that result from conventional AAO fabricating methods. First, plural AAOs are produced at one time through simultaneous multi-surfaces anodization (SMSA), indicating mass-producibility of the AAOs with comparable qualities. Second, those AAOs can be separated from the aluminum (Al) substrate by applying stair-like reverse biases (SRBs) in the same electrolyte used for the SMSAs, implying simplicity and green technological characteristics. Finally, a unit sequence consisting of the SMSAs sequentially combined with SRBs-based detachment can be applied repeatedly to the same Al substrate, which reinforces the advantages of this strategy and also guarantees the efficient usage of natural resources.


Assuntos
Óxido de Alumínio/química , Eletrólitos/química , Ácido Oxálico/química , Enxofre/química , Eletrodos
11.
Food Funct ; 7(12): 4935-4943, 2016 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-27841429

RESUMO

Previous work in our laboratory showed that alkali-solubilized corn arabinoxylan (CAX) has a slow initial, but later complete, in vitro human fecal fermentation. CAX and a moderately high molecular weight hydrolysate (CH) were propiogenic, and produced low levels of butyrate. Here, we show that oxalic acid-generated hydrolysates from CAX, which include a large xylooligosaccharide, and free arabinose fractions, increased short chain fatty acid (SCFA) production, which included relatively high levels of both propionate and butyrate, an unusual SCFA combination. Hydrolytic degradation of CAX by acid hydrolysis (0.05 M oxalic acid at 100 °C for 2 h) and subsequent graded ethanol precipitations were used to obtain mixtures with different molecular weight ranges. Ethanol-precipitated fractions (F 0-65%, F 65-75%, F 75-85%) were mostly lower than 100 kDa and F > 85% was composed of monosaccharides and oligosaccharides of DP 2-8. Oxalic acid treatment caused the removal of all single arabinose unit branch chains and some di/trisaccharide branch chains, producing lightly substituted xylan backbone fragments, most of which were in the oligosaccharide (DP < 10) size range. In vitro human fecal fermentation analyses showed all oxalic acid-hydrolysate fractions were slower fermenting than fructooligosaccharides (FOS), but produced similar or higher amounts of total SCFAs. Butyrate production in two hydrolyzate fractions was double that of CH, while propionate levels remained relatively high.


Assuntos
Fezes/química , Ácido Oxálico/química , Xilanos/química , Zea mays/química , Animais , Ácido Butírico , Fermentação , Manipulação de Alimentos , Humanos , Concentração de Íons de Hidrogênio , Propionatos
12.
J Colloid Interface Sci ; 482: 151-158, 2016 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-27501038

RESUMO

HYPOTHESIS: Silver nanoparticles (AgNPs) have emerged as a powerful weapon against antibiotic resistant microorganisms. However, most conventional AgNPs syntheses require the use of hazardous chemicals and generate toxic organic waste. Hence, in recent year's, plant derived and biomolecule based synthetics have has gained much attention. Cacao has been used for years for its medicinal benefits and contains a powerful reducing agent - oxalic acid. We hypothesized that, due to the presence of oxalic acid, cacao extract is capable of reducing silver nitrate (AgNO3) to produce AgNPs. EXPERIMENTS: In this study, AgNPs were synthesized by using natural cacao extract as a reducing and stabilizing agent. The reaction temperature, time and reactant molarity were varied to optimize the synthesis yield. FINDINGS: UV-visible spectroscopy (UV-vis), dynamic light scattering (DLS) and transmission electron microscopy (TEM) characterization demonstrated that the synthesized AgNPs were spherical particles ranging in size from 35 to 42.5nm. The synthesized AgNPs showed significant antibacterial activity against clinically relevant pathogens such as Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Staphylococcus epidermidis. Importantly, these green AgNPs are not cytotoxic to human dermal fibroblasts (HDFs) at concentrations below 32µg/ml. We conclude that cacao-based synthesis is a reproducible and sustainable method for the generation of stable antimicrobial silver nanoparticles with low cytotoxicity to human cells. The AgNPs synthesized in this work have promising properties for applications in the biomedical field.


Assuntos
Antibacterianos/síntese química , Cacau/química , Nanopartículas Metálicas/química , Ácido Oxálico/química , Prata/química , Antibacterianos/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Derme/citologia , Derme/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Humanos , Nanopartículas Metálicas/ultraestrutura , Testes de Sensibilidade Microbiana , Tamanho da Partícula , Extratos Vegetais/química , Cultura Primária de Células , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/crescimento & desenvolvimento , Prata/farmacologia , Nitrato de Prata/química , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento , Staphylococcus epidermidis/efeitos dos fármacos , Staphylococcus epidermidis/crescimento & desenvolvimento
13.
Int J Biol Macromol ; 91: 92-9, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27212213

RESUMO

In this paper, the novel polysaccharide PL-A11 was purified from an ammonium oxalate extract of Phellinus linteus mycelia. Its physicochemical properties, structural characteristics, and antioxidant activities were investigated. Results showed that PL-A11 had a weight-average molecular weight (Mw) of 13.8kDa and was mainly composed of arabinose, xylose, mannose, and glucose in a molar ratio of 1.1:1.3:1.0:6.6. The backbone of PL-A11 was composed of (1→4)-α-d-glucopyranosyl, (1→2)-α-d-xylopyranosyl, and (1→3)-α-d-arabinofuranosyl residues, whereas the (1→6)-α-d-mannopyranosyl residues formed branches at the O-2 position with 1-linked-α-d-glucopyranosyl terminal residues. From the antioxidative activity tests in vivo, the administration of PL-A11 obviously enhanced the activity of antioxidant enzymes and significantly reduced the level of malondiadehyde (MDA) in the serum and liver of d-galactose-treated aging mice in a dose-dependent manner, as well as effectively stimulated the immune system of aging mice. These findings implied that PL-A11 could be developed as a potential antioxidant for applications in the functional food, pharmaceutical, cosmetic or nutraceutical industries.


Assuntos
Antioxidantes/química , Antioxidantes/farmacologia , Ácido Oxálico/química , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Polissacarídeos/química , Polissacarídeos/farmacologia , Envelhecimento/metabolismo , Animais , Antioxidantes/isolamento & purificação , Feminino , Malondialdeído/metabolismo , Camundongos , Camundongos Endogâmicos ICR , Peso Molecular , Monossacarídeos/análise , Phellinus , Extratos Vegetais/isolamento & purificação , Polissacarídeos/isolamento & purificação , Relação Estrutura-Atividade , Vísceras/efeitos dos fármacos , Vísceras/metabolismo
14.
Huan Jing Ke Xue ; 37(1): 173-9, 2016 Jan 15.
Artigo em Chinês | MEDLINE | ID: mdl-27078955

RESUMO

To investigate the effect of low molecular weight organic acids ( LMWOA) on the ability of migration and the species of mercury in the soil of the Water-Level-Fluctuating Zone of the Three Gorges Reservoir, citric acid, tartaric acid and oxalic acid were dded into the soil to conduct simulation experiments. The results showed that the percentage of exchangeable mercury increased with the increase of the concentration of citric acid, but the value declined slightly as the concentration of tartaric acid and oxalic acid increased. While all three acids elevated the bioavailability of mercury, which increased with the increase of the concentration of acids. Vhen the concentration of citric acid reached 15 mmol x L(-1), the activation effect was the best. But for oxalic acid and citric acid, 10 mmol x L(-1) was the optimal concentration. In general, the effect of three organic acids on the activation of mercury in the soil followed the trend of citric acid > tartaric acid > oxalic acid. In the soil supplemented with 15 mmol x L(-1) citric acid, the change of mercury pecies was more and more striking with the prolonged incubation, and the conversion did not stop until 14 d, at that time the stomach cid dissolved mercury increased obviously, which was mainly converted from elemental mercury.


Assuntos
Ácido Cítrico/química , Mercúrio/química , Ácido Oxálico/química , Tartaratos/química , Poluentes Químicos da Água/análise , Disponibilidade Biológica , China , Peso Molecular , Solo , Água/química
15.
Carbohydr Polym ; 136: 1358-69, 2016 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-26572481

RESUMO

Polymers with different structures were isolated from the aboveground part of Heracleum sosnowskyi Manden. The sequential treatment of Heracleum with water, HCl solution, and (NH4)2C2O4 solution was observed to decrease the arabinogalactan proteins (AGP) content and increase the pectins content in the extracted polysaccharides. The linear region of the HSO-I polysaccharide having the highest yield was found to be composed mainly of partially methylesterified homogalacturonan fragments, whereas the branched region was made up of fragments of rhamnogalacturonan I whose core represents 1,2-α-L-rhamno-1,4-α-D-galacturonan. The carbohydrate side chains of the branched region are linked to the α-L-Rhap core residues via the 1,4-glycosidic bond and consist chiefly of T-ß-D-Galp, 1,4-ß-D-Galp and 1,6-ß-D-Galp residues indicating the presence of the 1,4-ß-D-galactan. NMR spectroscopy revealed the carbohydrate moiety of the AGP molecule to consist mainly of 1,3- and 1,3,6-ß-D-Galp residues. The side chains comprised 1,6-ß-D-Galp, terminal 4-O-Me-ß-D-GlcpA, and ß-D-Galp.


Assuntos
Heracleum/química , Mucoproteínas/química , Pectinas/química , Sequência de Carboidratos , Ácido Clorídrico/química , Hidrólise , Dados de Sequência Molecular , Mucoproteínas/isolamento & purificação , Ácido Oxálico/química , Pectinas/isolamento & purificação , Componentes Aéreos da Planta/química , Proteínas de Plantas/química , Proteínas de Plantas/isolamento & purificação , Água/química
16.
PLoS One ; 10(6): e0130030, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26121588

RESUMO

A field study was conducted to compare the formationand bacterial communities of rhizosheaths of wheat grown under wheat-cotton and wheat-rice rotation and to study the effects of bacterial inoculation on plant growth. Inoculation of Azospirillum sp. WS-1 and Bacillus sp. T-34 to wheat plants increased root length, root and shoot dry weight and dry weight of rhizosheathsoil when compared to non-inoculated control plants, and under both crop rotations. Comparing both crop rotations, root length, root and shoot dry weight and dry weight of soil attached with roots were higher under wheat-cotton rotation. Organic acids (citric acid, malic acid, acetic acid and oxalic acid) were detected in rhizosheaths from both rotations, with malic acid being most abundant with 24.8±2 and 21.3±1.5 µg g(-1) dry soil in wheat-cotton and wheat-rice rotation, respectively. Two sugars (sucrose, glucose) were detected in wheat rhizosheath under both rotations, with highest concentrations of sucrose (4.08±0.5 µg g(-1) and 7.36±1.0 µg g(-1)) and glucose (3.12±0.5 µg g(-1) and 3.01± µg g(-1)) being detected in rhizosheaths of non-inoculated control plants under both rotations. Diversity of rhizosheath-associated bacteria was evaluated by cultivation, as well as by 454-pyrosequencing of PCR-tagged 16S rRNA gene amplicons. A total of 14 and 12 bacterial isolates predominantly belonging to the genera Arthrobacter, Azospirillum, Bacillus, Enterobacter and Pseudomonaswere obtained from the rhizosheath of wheat grown under wheat-cotton and wheat-rice rotation, respectively. Analysis of pyrosequencing data revealed Proteobacteria, Bacteriodetes and Verrucomicrobia as the most abundant phyla in wheat-rice rotation, whereas Actinobacteria, Firmicutes, Chloroflexi, Acidobacteria, Planctomycetes and Cyanobacteria were predominant in wheat-cotton rotation. From a total of 46,971 sequences, 10.9% showed ≥97% similarity with 16S rRNA genes of 32 genera previously shown to include isolates with plant growth promoting activity (nitrogen fixation, phosphate-solubilization, IAA production). Among these, the most predominant genera were Arthrobacter, Azoarcus, Azospirillum, Bacillus, Cyanobacterium, Paenibacillus, Pseudomonas and Rhizobium.


Assuntos
Azospirillum/genética , Bacillus/genética , Microbiologia do Solo , Triticum/crescimento & desenvolvimento , Triticum/microbiologia , Ácido Acético/química , Agricultura , Azospirillum/fisiologia , Bacillus/fisiologia , Biodiversidade , Ácido Cítrico/química , Produtos Agrícolas , Glucose/química , Gossypium , Malatos/química , Nitrogênio/química , Oryza , Ácido Oxálico/química , Fósforo/química , Filogenia , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/microbiologia , Análise de Componente Principal , RNA Ribossômico 16S/metabolismo , Sacarose/química
17.
Chemosphere ; 125: 168-74, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25577698

RESUMO

In this study, electrokinetic-Fenton treatment was used to remediate a soil polluted with PAHs and the pesticide pyrimethanil. Recently, this treatment has emerged as an interesting alternative to conventional soil treatments due to its peculiar advantages, namely the capability of treating fine and low-permeability materials, as well as that of achieving a high yield in the removals of salt content and inorganic and organic pollutants. In a standard electrokinetic-Fenton treatment, the maximum degradation of the pollutant load achieved was 67%, due to the precipitation of the metals near the cathode chamber that reduces the electro-osmotic flow of the system and thus the efficiency of the treatment. To overcome this problem, different complexing agents and pH control in the cathode chamber were evaluated to increase the electro-osmotic flux as well as to render easier the solubilization of the metal species present in the soil. Four complexing agents (ascorbic acid, citric acid, oxalic acid and ethylenediaminetetraacetic acid) in the Fenton-like treatment were evaluated. Results revealed the citric acid as the most suitable complexing agent. Thereby its efficiency was tested as pH controller by flushing it in the cathode chamber (pH 2 and 5). For the latter treatments, near total degradation was achieved after 27 d. Finally, phytotoxicity tests for polluted and treated samples were carried out. The high germination levels of the soil treated under enhanced conditions concluded that nearly complete restoration was achieved.


Assuntos
Técnicas Eletroquímicas/métodos , Peróxido de Hidrogênio/química , Ferro/química , Praguicidas/isolamento & purificação , Hidrocarbonetos Policíclicos Aromáticos/isolamento & purificação , Poluentes do Solo/isolamento & purificação , Solo/química , Ácido Ascórbico , Ácido Cítrico/química , Ácido Edético/química , Eletrodos , Concentração de Íons de Hidrogênio , Ácido Oxálico/química , Permeabilidade , Praguicidas/análise , Hidrocarbonetos Policíclicos Aromáticos/análise , Pirimidinas , Poluentes do Solo/análise
18.
Langmuir ; 30(50): 15143-52, 2014 Dec 23.
Artigo em Inglês | MEDLINE | ID: mdl-25495551

RESUMO

By means of the in situ electrokinetic assessment of aqueous particles in conjunction with the addition of anionic adsorbates, we develop and examine a new approach to the scalable characterization of the specific accessible surface area of particles in water. For alumina powders of differing morphology in mildly acidic aqueous suspensions, the effective surface charge was modified by carboxylate anion adsorption through the incremental addition of oxalic and citric acids. The observed zeta potential variation as a function of the proportional reagent additive was found to exhibit inverse hyperbolic sine-type behavior predicted to arise from monolayer adsorption following the Grahame-Langmuir model. Through parameter optimization by inverse problem solving, the zeta potential shift with relative adsorbate addition revealed a nearly linear correlation of a defined surface-area-dependent parameter with the conventionally measured surface area values of the powders, demonstrating that the proposed analytical framework is applicable for the in situ surface area characterization of aqueous particulate matter. The investigated methods have advantages over some conventional surface analysis techniques owing to their direct applicability in aqueous environments at ambient temperature and the ability to modify analysis scales by variation of the adsorption cross section.


Assuntos
Água/química , Adsorção , Óxido de Alumínio/química , Ácido Cítrico/química , Ácido Oxálico/química , Propriedades de Superfície
19.
Artigo em Inglês | MEDLINE | ID: mdl-25274518

RESUMO

The aim of this study was to test the applicability of a Bruker AXS CMOS-type PHOTON 100 detector for the purpose of a fine charge density quality data collection. A complex crystal containing oxalic acid, ammonium oxalate and two water molecules was chosen as a test case. The data was collected up to a resolution of 1.31 Å(-1) with high completeness (89.1%; Rmrg = 0.0274). The multipolar refinement and subsequent quantum theory of atoms in molecules (QTAIM) analysis resulted in a comprehensive description of the charge density distribution in the crystal studied. The residual density maps are flat and almost featureless. It was possible to derive reliable information on intermolecular interactions to model the anharmonic motion of a water molecule, and also to observe the fine details of the charge density distribution, such as polarization on O and H atoms involved in the strongest hydrogen bonds. When compared with our previous statistical study on oxalic acid data collected with the aid of CCD cameras, the complementary metal-oxide semiconductor (CMOS) detector can certainly be classified as a promising alternative in advanced X-ray diffraction studies.


Assuntos
Compostos de Amônio/química , Modelos Moleculares , Oxalatos/química , Ácido Oxálico/química , Difração de Raios X/instrumentação , Difração de Raios X/métodos , Cristalografia por Raios X/instrumentação , Cristalografia por Raios X/métodos , Ligação de Hidrogênio , Estrutura Molecular , Fótons , Teoria Quântica , Semicondutores
20.
Carbohydr Polym ; 112: 300-7, 2014 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-25129748

RESUMO

A group of 12 polysaccharide extracts were prepared from the tips, stem and roots of an Indian halophyte Salicornia brachiata Roxb. obtained by sequential extractions with cold water (CW), hot water (HW), aqueous ammonium oxalate (OX) and aqueous sodium hydroxide (ALK) solutions. Monosaccharide composition analysis revealed that all the polysaccharide extract samples consisted primarily of rhamnose, arabinose, mannose, galactose, glucose, whereas ribose and xylose were present only in some of the extracts. All the extracts exhibited low apparent viscosity (1.47-2.02 cP) and sulphate and contained no prominent toxic metal ions. Fucose was detected only in OX extract of the roots. These polysaccharides were found to be heterogeneous and highly branched (glycoside linkage analysis, size-exclusion chromatography, (13)C-NMR, FT-IR, circular dichroism and optical rotation data). Physico-chemical analyses of these polysaccharides including uronic acid, sulphate and protein contents were also carried out. This constitutes the first report on the profiling of Salicornia polysaccharides.


Assuntos
Chenopodiaceae/química , Polissacarídeos/química , Configuração de Carboidratos , Dicroísmo Circular , Fucose/análise , Espectroscopia de Ressonância Magnética , Monossacarídeos/análise , Ácido Oxálico/química , Extratos Vegetais/química , Raízes de Plantas/química , Caules de Planta/química , Polissacarídeos/análise , Espectroscopia de Infravermelho com Transformada de Fourier
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