Study of poly-L-lysine conformations in aqueous methanol solution by using polarized Raman techniques.

PubMed Central

Shepherd, I W

1976-01-01

Raman polarization measurements of the amide I band are reported in ionized poly-L-lysine dissolved in aqueous methanol. The observed changes with methanol concentration, attributed to changes in coil conformation and to the helix-coil transition, represent a novel method of measuring polymer conformation. Polarization measurements as a function of temperature yield values of the energy differences between rotational isomeric states in the coil. deltaH, of 8.8 +/- 0.7, 10.4 +/- 1.1 and 10.8 +/- 1.5 kJ/mol at methanol concentrations (v/v) of 85, 80 and 70% respectively. The stabilization energy of the helix is estimated at 9.3 kJ/mol. PMID:949317

Temperature of maximum density and excess thermodynamics of aqueous mixtures of methanol

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

González-Salgado, D.; Zemánková, K.; Noya, E. G.

In this work, we present a study of representative excess thermodynamic properties of aqueous mixtures of methanol over the complete concentration range, based on extensive computer simulation calculations. In addition to test various existing united atom model potentials, we have developed a new force-field which accurately reproduces the excess thermodynamics of this system. Moreover, we have paid particular attention to the behavior of the temperature of maximum density (TMD) in dilute methanol mixtures. The presence of a temperature of maximum density is one of the essential anomalies exhibited by water. This anomalous behavior is modified in a non-monotonous fashion bymore » the presence of fully miscible solutes that partly disrupt the hydrogen bond network of water, such as methanol (and other short chain alcohols). In order to obtain a better insight into the phenomenology of the changes in the TMD of water induced by small amounts of methanol, we have performed a new series of experimental measurements and computer simulations using various force fields. We observe that none of the force-fields tested capture the non-monotonous concentration dependence of the TMD for highly diluted methanol solutions.« less

Catalytic and electrocatalytic hydrogenolysis of brominated diphenyl ethers.

PubMed

Bonin, Pascale M L; Edwards, Patrick; Bejan, Dorin; Lo, Chun Chi; Bunce, Nigel J; Konstantinov, Alexandre D

2005-02-01

Polybrominated diphenyl ethers (PBDEs) are ubiquitous environmental contaminants due to their use as additive flame-retardants. Conventional catalytic hydrogenolysis in methanol solution and electrocatalytic hydrogenolysis in aqueous methanol were examined as methods for debrominating mono- and di-bromodiphenyl ethers, as well as a commercial penta-PBDE mixture, in each case using palladium on alumina as the catalyst. Electrocatalytic hydrogenolysis employed a divided flow-through batch cell, with reticulated vitreous carbon cathodes and IrO2/Ti dimensionally stable anodes. Both methods gave efficient sequential debromination, with essentially complete removal of bromine from the PBDEs, but the electrocatalytic method was limited by the poor solubility of PBDEs in aqueous methanol.

Compact Fuel-Cell System Would Consume Neat Methanol

NASA Technical Reports Server (NTRS)

Narayanan, Sekharipuram; Kindler, Andrew; Valdez, Thomas

2007-01-01

In a proposed direct methanol fuel-cell electric-power-generating system, the fuel cells would consume neat methanol, in contradistinction to the dilute aqueous methanol solutions consumed in prior direct methanol fuel-cell systems. The design concept of the proposed fuel-cell system takes advantage of (1) electro-osmotic drag and diffusion processes to manage the flows of hydrogen and water between the anode and the cathode and (2) evaporative cooling for regulating temperature. The design concept provides for supplying enough water to the anodes to enable the use of neat methanol while ensuring conservation of water for the whole fuel-cell system.

Carbon Dioxide to Methanol: The Aqueous Catalytic Way at Room Temperature.

PubMed

Sordakis, Katerina; Tsurusaki, Akihiro; Iguchi, Masayuki; Kawanami, Hajime; Himeda, Yuichiro; Laurenczy, Gábor

2016-10-24

Carbon dioxide may constitute a source of chemicals and fuels if efficient and renewable processes are developed that directly utilize it as feedstock. Two of its reduction products are formic acid and methanol, which have also been proposed as liquid organic chemical carriers in sustainable hydrogen storage. Here we report that both the hydrogenation of carbon dioxide to formic acid and the disproportionation of formic acid into methanol can be realized at ambient temperature and in aqueous, acidic solution, with an iridium catalyst. The formic acid yield is maximized in water without additives, while acidification results in complete (98 %) and selective (96 %) formic acid disproportionation into methanol. These promising features in combination with the low reaction temperatures and the absence of organic solvents and additives are relevant for a sustainable hydrogen/methanol economy. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Study on viscosity of MDEA-MeOH aqueous solutions

NASA Astrophysics Data System (ADS)

Wang, F.; Wang, L. M.; Wang, S. Q.; Fu, D.

2017-03-01

The viscosities of the N-methyldiethanolamine (MDEA)-methanol (MeOH) aqueous solutions were measured at temperatures ranging from (303.2 to 323.2) K. The mass fraction of MDEA and MeOH respectively ranged from 0.2 to 0.4 and 0 to 0.15. On the basis of experimental measurement, the effects of temperature, mass fraction of MDEA and MeOH on viscosities were demonstrated.

Investigation into the temporal stability of aqueous standard solutions of psilocin and psilocybin using high performance liquid chromatography.

PubMed

Anastos, N; Barnett, N W; Pfeffer, F M; Lewis, S W

2006-01-01

This paper reports an investigation into the temporal stability of aqueous solutions of psilocin and psilocybin reference drug standards over a period of fourteen days. This study was performed using high performance liquid chromatography utilising a (95:5% v/v) methanol: 10 mM ammonium formate, pH 3.5 mobile phase and absorption detection at 269 nm. It was found that the exclusion of light significantly prolonged the useful life of standards, with aqueous solutions of both psilocin and psilocybin being stable over a period of seven days.

Fabrication of Pt/Au concentric spheres from triblock copolymer.

PubMed

Koh, Haeng-Deog; Park, Soojin; Russell, Thomas P

2010-02-23

Dispersion of an aqueous H(2)PtCl(6) solution into a trifluorotoluene (TFT) solution of a polystyrene-block-poly(2-vinylpyridine)-block-poly(ethylene oxide) (PS-b-P2VP-b-PEO) triblock copolymer produced an emulsion-induced hollow micelle (EIHM), comprising a water nanodroplet stabilized by PEO, H(2)PtCl(6)/P2VP, and PS, sequentially. The following addition of an aqueous LiAuCl(4) solution into the dispersion led to a coordination of LiAuCl(4) and PEO. The resulting spherical EIHM structure was transformed to a hollow cylindrical micelle by the fusion of spherical EIHM with the addition of methanol. This structural transition was reversible by the alternative addition of methanol and TFT. Oxygen plasma was used to generate Pt/Au concentric spheres and hollow cylindrical Pt/Au nano-objects.

Optimizing the deposition of hydrogen evolution sites on suspended semiconductor particles using on-line photocatalytic reforming of aqueous methanol solutions.

PubMed

Busser, G Wilma; Mei, Bastian; Muhler, Martin

2012-11-01

The deposition of hydrogen evolution sites on photocatalysts is a crucial step in the multistep process of synthesizing a catalyst that is active for overall photocatalytic water splitting. An alternative approach to conventional photodeposition was developed, applying the photocatalytic reforming of aqueous methanol solutions to deposit metal particles on semiconductor materials such as Ga₂O₃ and (Ga₀.₆ Zn₀.₄)(N₀.₆O₀.₄). The method allows optimizing the loading of the co-catalysts based on the stepwise addition of their precursors and the continuous online monitoring of the evolved hydrogen. Moreover, a synergetic effect between different co-catalysts can be directly established. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

New Fluorinated and Sulfonated Block Copolymers Final Report

DTIC Science & Technology

2009-04-23

use polymers namely, Polymer Electrolyte Membrane Fuel Cells ( PEMFC ) and Direct Methanol Fuel Cells (DMFC) The DMFC can be seen as a variant of...the PEMFC . The membranes are typically the same; however, the feed for DMFC is methanol in an aqueous 1-2 M solution or in its vapor form. This fuel...the existing liquid fuels infrastructure can be used for methanol. Catalysts, as well as operating temperature ranges, are very similar to the PEMFC

Monitoring methanol-induced protein unfolding by fluorescence anisotropy measurements of covalently labelled rhodamine probe*

NASA Astrophysics Data System (ADS)

Soleilhac, Antonin; Bertorelle, Franck; Dugourd, Philippe; Girod, Marion; Antoine, Rodolphe

2017-06-01

We describe the use of an extrinsic fluorophore (rhodamine B isothiocyanate) as a versatile probe to measure rotational motions of proteins. To illustrate the usefulness of this probe, we describe the fluorescence anisotropy values of this fluorophore covalently linked to myoglobin protein measured in aqueous solutions of increased methanol content. Methanol-induced unfolding is revealed by the transition from constrained to free rotation of the covalently attached rhodamine B fluorophore.

Preparation of Cu-loaded SrTiO3 nanoparticles and their photocatalytic activity for hydrogen evolution from methanol aqueous solution

NASA Astrophysics Data System (ADS)

Bui, Duc-Nguyen; Mu, Jin; Wang, Lei; Kang, Shi-Zhao; Li, Xiangqing

2013-06-01

Cu-loaded SrTiO3 nanoparticles (Cu-SrTiO3) were prepared using a simple in situ photo-deposition method and their photocatalytic activity for hydrogen evolution from methanol aqueous solution was evaluated. The results characterized with XRD, TEM, XPS and EDX indicated that the as-synthesized sample was composed of metallic Cu and cubic SrTiO3, and the metallic Cu was homogeneously loaded on the surface of SrTiO3 nanoparticles. Under UV light irradiation, Cu-SrTiO3 displayed much higher photocatalytic activity for hydrogen evolution and excellent stability in comparison with pure SrTiO3 nanoparticles. The results further confirmed that the efficient separation of photogenerated electron/hole pairs was critical for the enhanced photocatalytic activity of Cu-SrTiO3. Moreover, the rate of hydrogen evolution of 0.5 wt.% Cu-SrTiO3 is comparable with that of 0.5 wt.% Pt-SrTiO3 photocatalyst under optimum conditions, implying that the metallic Cu is an efficient alternative to Pt as a co-catalyst on SrTiO3. The high photocatalytic activity, low cost and chemical stability mean that the Cu-loaded SrTiO3 is a potential catalyst for the photocatalytic hydrogen evolution from methanol aqueous solution.

ZnS/Zn(O,OH)S-based buffer layer deposition for solar cells

DOEpatents

Bhattacharya, Raghu N [Littleton, CO

2009-11-03

The invention provides CBD ZnS/Zn(O,OH)S and spray deposited ZnS/Zn(O,OH)S buffer layers prepared from a solution of zinc salt, thiourea and ammonium hydroxide dissolved in a non-aqueous/aqueous solvent mixture or in 100% non-aqueous solvent. Non-aqueous solvents useful in the invention include methanol, isopropanol and triethyl-amine. One-step deposition procedures are described for CIS, CIGS and other solar cell devices.

Bronchodilatory and B-adrenergic effects of methanolic and aqueous extracts of Althaea root on isolated tracheobronchial smooth rat muscle.

PubMed

Alani, Behrang; Zare, Mohammad; Noureddini, Mahdi

2015-01-01

The smooth muscle contractions of the tracheobronchial airways are mediated through the balance of adrenergic, cholinergic and peptidergic nervous mechanisms. This research was designed to determine the bronchodilatory and B-adrenergic effects of methanolic and aqueous extracts of root Althaea on the isolated tracheobronchial smooth muscle of the rat. In this experimental study, 116 tracheobronchial sections (5 mm) from 58 healthy male Sprague-Dawley rats were dissected and divided into 23 groups. The effect of methanolic and aqueous extracts of the root Althaea was assayed at different concentrations (0.2, 0.6, 2.6, 6.6, 14.6 μg/ml) and epinephrine (5 μm) in the presence and absence of propranolol (1 μM) under one g tension based on the isometric method. This assay was recorded in an organ bath containing Krebs-Henseleit solution for tracheobronchial smooth muscle contractions using potassium chloride (KCl) (60 mM) induction. Epinephrine (5 μm) alone and root methanolic and aqueous extract concentrations (0.6-14.6 μg/ml) reduced tracheobronchial smooth muscle contractions induced using KCl (60 mM) in a dose dependent manner. Propranolol inhibited the antispasmodic effect of epinephrine on tracheobronchial smooth muscle contractions, but could not reduce the antispasmodic effect of the root extract concentrations. The methanolic and aqueous extracts of Althaea root inhibited the tracheobronchial smooth muscle contractions of rats in a dose dependent manner, but B-adrenergic receptors do not appear to engage in this process. Understanding the mechanism of this process can be useful in the treatment of pulmonary obstructive diseases like asthma.

40 CFR 796.1050 - Absorption in aqueous solution: Ultraviolet/visible spectra.

Code of Federal Regulations, 2011 CFR

2011-07-01

....50 λ in nm 235 257 313 350 (2) Fluoranthene (in methanol) from C.R.C. Atlas of Spectral Data...-nitrophenol (in methanol) from C.R.C. Atlas of Spectral Data, paragraph (d)(3) of this section: log ε 3.88 4... to obtain the UV-VIS spectrum of the test compound. Such an instrument should have a photometric...

Modeling and Simulation of the Direct Methanol Fuel Cell

NASA Technical Reports Server (NTRS)

Wohr, M.; Narayanan, S. R.; Halpert, G.

1996-01-01

From intro.: The direct methanol liquid feed fuel cell uses aqueous solutions of methanol as fuel and oxygen or air as the oxidant and uses an ionically conducting polymer membrane such as Nafion(sup r)117 and the electrolyte. This type of direct oxidation cell is fuel versatile and offers significant advantages in terms of simplicity of design and operation...The present study focuses on the results of a phenomenological model based on current understanding of the various processed operating in these cells.

Facile approach to prepare Pt decorated SWNT/graphene hybrid catalytic ink

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

Mayavan, Sundar, E-mail: sundarmayavan@cecri.res.in; Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon, 305-701; Mandalam, Aditya

Highlights: • Pt NPs were in situ synthesized onto CNT–graphene support in aqueous solution. • The as-prepared material was used directly as a catalyst ink without further treatment. • Catalyst ink is active toward methanol oxidation. • This approach realizes both scalable and greener production of hybrid catalysts. - Abstract: Platinum nanoparticles were in situ synthesized onto hybrid support involving graphene and single walled carbon nanotube in aqueous solution. We investigate the reduction of graphene oxide, and platinum nanoparticle functionalization on hybrid support by X-ray photoelectron spectroscopy, Raman spectroscopy, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The as-preparedmore » platinum on hybrid support was used directly as a catalyst ink without further treatment and is active toward methanol oxidation. This work realizes both scalable and greener production of highly efficient hybrid catalysts, and would be valuable for practical applications of graphene based fuel cell catalysts.« less

Conformation Types of Ubiquitin [M+8H]8+ Ions from Water:Methanol Solutions: Evidence for the N and A States in Aqueous Solution

PubMed Central

Shi, Huilin; Pierson, Nicholas A.; Valentine, Stephen J.; Clemmer, David E.

2012-01-01

Ion mobility and mass spectrometry measurements are used to examine the gas-phase populations of [M+8H]8+ ubiquitin ions formed upon electrospraying 20 different solutions: from 100:0 to 5:95 water:methanol that are maintained at pH = 2.0. Over this range of solution conditions, mobility distributions for the +8 charge state show substantial variations. Here we develop a model that treats the combined measurements as one data set. By varying the relative abundances of a discrete set of conformation types, it is possible to represent distributions obtained from any solution. For solutions that favor the well-known A-state ubiquitin, it is possible to represent the gas-phase distributions with seven conformation types. Aqueous conditions that favor the native structure require four more structural types to represent the distribution. This analysis provides the first direct evidence for trace amounts of the A state under native conditions. The method of analysis presented here should help illuminate how solution populations evolve into new gas-phase structures as solvent is removed. Evidence for trace quantities of previously unknown states under native solution conditions may provide insight about the relationship of dynamics to protein function as well as misfolding and aggregation phenomena. PMID:22315998

40 CFR 796.1050 - Absorption in aqueous solution: Ultraviolet/visible spectra.

Code of Federal Regulations, 2010 CFR

2010-07-01

... organic solvent should be used (methanol preferred). (3) The acid medium should have a pH of less than 2...) Milazzo, G., Caroli, S., Palumbo-Doretti, M., Violante, N., Analytical Chemistry, 49: 711 (1977). (2...

Simply enhancing throughput of free-flow electrophoresis via organic-aqueous environment for purification of weak polarity solute of phenazine-1-carboxylic acid in fermentation of Pseudomonas sp. M18.

PubMed

Yang, Jing-Hua; Shao, Jing; Wang, Hou-Yu; Dong, Jing-Yu; Fan, Liu-Yin; Cao, Cheng-Xi; Xu, Yu-Quan

2012-09-01

Herein, a simple novel free-flow electrophoresis (FFE) method was developed via introduction of organic solvent into the electrolyte system, increasing the solute solubility and throughput of the sample. As a proof of concept, phenazine-1-carboxylic acid (PCA) from Pseudomonas sp. M18 was selected as a model solute for the demonstration on feasibility of novel FFE method on account of its faint solubility in aqueous circumstance. In the developed method, the organic solvent was added into not only the sample buffer to improve the solubility of the solute, but also the background buffer to construct a uniform aqueous-organic circumstance. These factors of organic solvent percentage and types as well as pH value of background buffer were investigated for the purification of PCA in the FFE device via CE. The experiments revealed that the percentage and the types of organic solvent exerted major influence on the purification of PCA. Under the optimized conditions (30 mM phosphate buffer in 60:40 (v/v) water-methanol at an apparent pH 7.0, 3.26 mL/min background flux, 10-min residence time of injected sample, and 400 V), PCA could be continuously purified from its impurities. The flux of sample injection was 10.05 μL/min, and the recovery was up to 93.7%. An 11.9-fold improvement of throughput was found with a carrier buffer containing 40% (v/v) methanol, compared with the pure aqueous phase. The developed procedure is of evident significance for the purification of weak polarity solute via FFE. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gas chromatography/isotope ratio mass spectrometry: analysis of methanol, ethanol and acetic acid by direct injection of aqueous alcoholic and acetic acid samples.

PubMed

Ai, Guomin; Sun, Tong; Dong, Xiuzhu

2014-08-15

Methanol, ethanol, and acetic acid are not easily extracted from aqueous samples and are susceptible to isotope fractionation in gas chromatography/isotope ratio mass spectrometry (GC/IRMS) analysis. Developing a direct dilution GC/IRMS method for aqueous samples, by adjusting the sample concentrations in common solvents to be similar to each other and using a fixed GC split ratio, is very convenient and important because any linearity effects caused by amount-dependent isotope fractionation can be avoided. The suitability of acetonitrile and acetone solvents for the GC/IRMS analysis of pure methanol, ethanol and acetic acid, and commercial liquor and vinegar samples was evaluated using n-hexane and water as control solvents. All the solvents including water were separated from the analyte on a HP-INNOWAX column and were diverted away from the combustion interface. The influence of liquor matrix on the ethanol GC/IRMS analyses was evaluated by adding pure ethanol to liquor samples. Acetonitrile and acetone gave similar δ(13) C values for pure ethanol and pure acetic acid to those obtained in water and n-hexane, and also gave similar δ(13) C values of ethanol in liquor and acetic acid in white vinegar to that obtained in water. For methanol analysis, acetonitrile and refined acetone gave similar δ(13) C values to that obtained in water, but n-hexane was not a suitable solvent. In addition, isotopic fractionation caused by solvent and solute interactions was observed. We recommend using acetonitrile for the GC/IRMS analysis of aqueous alcoholic samples, and acetone for the analysis of aqueous acetic acid samples. This direct dilution method can provide high accurate and precise GC/IRMS analysis of the relative changes in δ(13) C values of methanol, ethanol, and acetic acid. Copyright © 2014 John Wiley & Sons, Ltd.

Plasma application for detoxification of Jatropha phorbol esters

NASA Astrophysics Data System (ADS)

Kongmany, S.; Matsuura, H.; Furuta, M.; Okuda, S.; Imamura, K.; Maeda, Y.

2013-06-01

Atmospheric pressure non-thermal dielectric barrier discharge (DBD) plasma generated by helium gas at high voltage and input power of about 50 W was first applied to detoxification of Jatropha curcas phorbol esters (J. PEs) as well as standard phorbol ester (4β-12-O-tetradecanoyl phorbol-13-acetate, TPA) in water and methanol. Plasma irradiation on the solution sample was conducted for 15 min. In aqueous solution, only 16% of TPA was degraded and complete degradation of J. PEs was observed. On the contrary, complete degradation of both TPA and J. PEs in methanol was achieved by the same plasma irradiation condition. Hydroxyl radical (•OH) generated by plasma irradiation of the solution is expected as the main radical inducing the degradation of PEs.

THE EFFECT OF METHANOL USED AS VEHICULUM ON SERUM PHENACETIN CONCENTRATION IN THE RAT.

PubMed

Lukasik, Marcin; Malkowska, Anna; Bamburowicz-Klimkowska, Magdalena; Polak, Piotr; Szutowski, Miroslaw M

2016-09-01

The xenobiotic absorption process is dependent on many factors, related both to the substance and form of its administration. During administration of small amounts of drugs, the effect of vehiculum on drug fate in the body becomes also evident. The intensity of absorption depends on numerous factors not necessarily related to the substance and its formulation, and also on biotransformation and active transport processes. Additional problem is the fact that many medicines are lipophilic compounds and insoluble in the water (e.g. phenacetin). Methanol and its aqueous solutions facilitate administration to the experimental animals, in the dissolved form of a number of medicines practically insoluble in water. Taking into consideration that methanol is particularly for rats, of low toxicity, it is quite frequently applied as vehiculum. The aim of this study was to investigate the potential interactions that may occur during the use of methanol as vehiculum and compare changes when were used solution 1% of carboxymethylcellulose. The study was performed on male Wistar rats. The tests were performed using phenacetin, which is recognized as biomarker of CYP 2E 1 isoform activity. Phenacetin was given per os in a single dose of 100 mg/kg b. w. Various procedures of phenacetin administration were tested, including solubilization in methanol or suspension in 1% water solution of carboxymethylcellulose. The results of this study show that methanol influences the phenacetin bioavailability and kinetics. Comparing the administration of this drug in methanol solutions against 1% of carboxymethylcellulose, it is in the case of phenacetin triple increase in AUC0-4 h. The presence of methanol affects the shape of kinetic curves of phenacetin causing higher their course until 4 hours after administration.

New Supercharging Reagents Produce Highly Charged Protein Ions in Native Mass Spectrometry

PubMed Central

Going, Catherine C.; Xia, Zijie; Williams, Evan R.

2015-01-01

The effectiveness of two new supercharging reagents for producing highly charged ions by electrospray ionization (ESI) from aqueous solutions in which proteins have native structures and reactivities were investigated. In aqueous solution, 2-thiophenone and 4-hydroxymethyl-1,3-dioxolan-2-one (HD) at a concentration of 2% by volume can increase the average charge of cytochrome c and myoglobin by up to 163%, resulting in even higher charge states than those that are produced from water/methanol/acid solutions in which proteins are denatured. The greatest extent of supercharging occurs in pure water, but these supercharging reagents are also highly effective in aqueous solutions containing 200 mM ammonium acetate buffer commonly used in native mass spectrometry (MS). These reagents are less effective supercharging reagents than m-nitrobenzyl alcohol (m-NBA) and propylene carbonate (PC) when ions are formed from water/methanol/acid. The extent to which loss of the heme group from myoglobin occurs is related to the extent of supercharging. Results from guanidine melts of cytochrome c monitored with tryptophan fluorescence show that the supercharging reagents PC, sulfolane and HD are effective chemical denaturants in solution. These results provide additional evidence for the role of protein structural changes in the electrospray droplet as the primary mechanism for supercharging with these reagents in native MS. These results also demonstrate that for at least some proteins, the formation of highly charged ions from native MS is no longer a significant barrier for obtaining structural information using conventional tandem MS methods. PMID:26421324

Phytochemical Screening and Antimicrobial Properties of a Common Brand of Black Tea (Camellia sinensis) Marketed in Nigerian Environment.

PubMed

Olosunde, O Funmilayo; Abu-Saeed, Kamaldeen; Abu-Saeed, Muhammad Buhari

2012-01-01

This study is aimed at determining chemical constituents and antimicrobial activities of a common brand of black tea (Lipton®) in Nigeria. Standard methods were employed for testing carbohydrates, tannins, saponins, flavonoids, alkaloids, steroids and terpenes in the tea. Antimicrobial activities of methanolic and aqueous extracts of the tea on four standard strains of organisms: Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis were also determined by standard methods. RESULTs showed that the tea contains tannin and reducing sugar. Concentrations of 1%, 2%, 4%, 6%, 8% and 10% aqueous and methanolic extract of black tea were prepared and their zones of inhibition determined against the four test organisms using the cup plate method. This was compared with zones for standard disc Gentamicin (10 µg) and Erythromycin (15 µg). Pseudomonas aeruginosa was sensitive to 2% to 10% aqueous extracts and intermediate to 6%, 8% and 10% methanolic extracts. E. coli was intermediately sensitive to 6%, 8% and 10% aqueous extract and 2% to 10% methanolic extracts. B. subtilis was intermediately sensitive to 4%, 6% and 8% aqueous extract and 4% to 10% methanolic extract but sensitive to 10% aqueous extract. Staph.aureus was intermediately sensitive to 4% to 10% aqueous extracts and 2% to 10% methanolic extracts. B. subtilis had the lowest MIC values of both aqueous and methanolic extracts. In conclusion, this study has shown that Lipton® has antimicrobial properties on E.coli, Staph.aureus, B.subtilis and Ps.aeruginosa and contains tannin and reducing sugar.

Comparative Analysis of Phenolics, Flavonoids, and Antioxidant and Antibacterial Potential of Methanolic, Hexanic and Aqueous Extracts from Adiantum caudatum Leaves.

PubMed

Ahmed, Dildar; Khan, Muhammad Mehboob; Saeed, Ramsha

2015-06-04

In the quest for new medicines, the methanolic, hexanic, and aqueous extracts of Adiantum caudatum leaves, obtained by Soxhlet extraction, were analyzed for phenolic and flavonoid contents, and antioxidant and antimicrobial potential. TPCs (total phenolic content) of the methanolic, aqueous and hexanic extracts were 27.7, 21.1, and 16.7 μg of gallic acid equivalents per mL, respectively, while TFCs (total flavonoid content) were 13.2, 11.6, and 10.0 μg of rutin equivalents per mL, respectively. Antioxidant activities of the extracts in reducing power, FRAP (ferric reducing antioxidant power), phosphomolybdate and ABTS assays follow the same order of methanolic ˃ aqueous ˃ hexanic. In the DPPH assay, however, the aqueous extract exhibited a slightly higher antioxidant activity than the methanolic one. Methanol is therefore a better solvent to extract most of the antioxidant components from A. caudatum leaves. In lipid peroxidation inhibitory assay, the extracts showed almost similar behavior and their activity decreased gradually with time. The aqueous extract was the strongest inhibitor after two days, but the hexanic became the most potent after about three days. The antibacterial potential of the extracts was determined against Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa. Towards all the microbes, the aqueous extract was the most potent and the hexanic the least. P. aeruginosa was the most susceptible strain, while the aqueous and methanolic extracts exhibited a slightly higher efficacy against this pathogen than the drug amoxicillin. In conclusion, A. caudatum can potentially provide a remedy against disorders caused by oxidative stress and infections.

Zinc Removal from the Aqueous Solutions by the Chemically Modified Biosorbents.

PubMed

Rajczykowski, Krzysztof; Sałasińska, Oktawia; Loska, Krzysztof

2018-01-01

Biosorbents are the natural origin adsorbents, which popularity in environmental engineering is steadily increasing due to their low price, ease of acquisition, and lack of the toxic properties. Presented research aimed to analyze the possibility of chemical modification of the straw, which is a characteristic waste in the Polish agriculture, to improve its biosorption properties with respect to removal of selected metals from aquatic solutions. Biosorbents used during the tests was a barley straw that was shredded to a size in the range of 0.2-1.0 mm. The biosorption process was performed for aqueous solutions of zinc at a pH 5. Two different modifications of straw were analyzed: esterification with methanol and modification using the citric acid at elevated temperature. The results, obtained during the research, show a clear improvement in sorption capacity of the straw modified by the citric acid. In the case of straw modified with methanol, it has been shown that the effectiveness of zinc biosorption process was even a twice lower with respect to the unmodified straw. Moreover, it was concluded that the removal of analyzed metals was based mainly on the ion-exchange adsorption mechanism by releasing a calcium and magnesium ions from the straw surface to the solution. Graphical Abstractᅟ.

Preferential solvation and solvation shell composition of free base and protonated 5, 10, 15, 20-tetrakis(4-sulfonatophenyl)porphyrin in aqueous organic mixed solvents

NASA Astrophysics Data System (ADS)

Farajtabar, Ali; Jaberi, Fatemeh; Gharib, Farrokh

2011-12-01

The solvatochromic properties of the free base and the protonated 5, 10, 15, 20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS) were studied in pure water, methanol, ethanol (protic solvents), dimethylsulfoxide, DMSO, (non-protic solvent), and their corresponding aqueous-organic binary mixed solvents. The correlation of the empirical solvent polarity scale ( ET) values of TPPS with composition of the solvents was analyzed by the solvent exchange model of Bosch and Roses to clarify the preferential solvation of the probe dyes in the binary mixed solvents. The solvation shell composition and the synergistic effects in preferential solvation of the solute dyes were investigated in terms of both solvent-solvent and solute-solvent interactions and also, the local mole fraction of each solvent composition was calculated in cybotactic region of the probe. The effective mole fraction variation may provide significant physico-chemical insights in the microscopic and molecular level of interactions between TPPS species and the solvent components and therefore, can be used to interpret the solvent effect on kinetics and thermodynamics of TPPS. The obtained results from the preferential solvation and solvent-solvent interactions have been successfully applied to explain the variation of equilibrium behavior of protonation of TPPS occurring in aqueous organic mixed solvents of methanol, ethanol and DMSO.

Peroxidase-catalyzed stabilization of 2,4-dichlorophenol in alkali-extracted soils.

PubMed

Palomo, Mónica; Bhandari, Alok

2011-01-01

Horseradish peroxidase- (HRP) mediated stabilization of phenolic contaminants is a topic of interest due to its potential for remediation of contaminated soils. This study evaluated the sorption of 2,4-dichlorophenol (DCP) and its HRP-mediated stabilization in two alkali-extracted soils. Alkali extraction reduced the soil organic matter (SOM) contents of the geomaterials and enriched the residual SOM with humin C. Sorption of DCP on these sorbents was complete within 1 d. However, most of the sorbed DCP was removed from the geomaterials by water and methanol, suggesting weak solute-sorbent interactions. The addition of HRP resulted in the generation of DCP polymerization products (DPP), which partitioned between the aqueous and solid phases. The DPP phase distribution was rapid and complete within 24 h. Between 70 and 90% of the added DCP was converted to DPP and up to 43% of the initial aqueous phase contaminant was transformed into a residue that was resistant to extraction with methanol. Bound residues of DPP increased with initial aqueous phase solute concentration and remained fairly constant after 7 d of contact. Contaminant stabilization was noted to be high in the humin-mineral geomaterial. Results illustrate that HRP may be effective in stabilizing phenolic contaminants in subsoils that are likely to contain SOM enriched in humin C.

Comparative Analysis of Phenolics, Flavonoids, and Antioxidant and Antibacterial Potential of Methanolic, Hexanic and Aqueous Extracts from Adiantum caudatum Leaves

PubMed Central

Ahmed, Dildar; Khan, Muhammad Mehboob; Saeed, Ramsha

2015-01-01

In the quest for new medicines, the methanolic, hexanic, and aqueous extracts of Adiantum caudatum leaves, obtained by Soxhlet extraction, were analyzed for phenolic and flavonoid contents, and antioxidant and antimicrobial potential. TPCs (total phenolic content) of the methanolic, aqueous and hexanic extracts were 27.7, 21.1, and 16.7 μg of gallic acid equivalents per mL, respectively, while TFCs (total flavonoid content) were 13.2, 11.6, and 10.0 μg of rutin equivalents per mL, respectively. Antioxidant activities of the extracts in reducing power, FRAP (ferric reducing antioxidant power), phosphomolybdate and ABTS assays follow the same order of methanolic ˃ aqueous ˃ hexanic. In the DPPH assay, however, the aqueous extract exhibited a slightly higher antioxidant activity than the methanolic one. Methanol is therefore a better solvent to extract most of the antioxidant components from A. caudatum leaves. In lipid peroxidation inhibitory assay, the extracts showed almost similar behavior and their activity decreased gradually with time. The aqueous extract was the strongest inhibitor after two days, but the hexanic became the most potent after about three days. The antibacterial potential of the extracts was determined against Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa. Towards all the microbes, the aqueous extract was the most potent and the hexanic the least. P. aeruginosa was the most susceptible strain, while the aqueous and methanolic extracts exhibited a slightly higher efficacy against this pathogen than the drug amoxicillin. In conclusion, A. caudatum can potentially provide a remedy against disorders caused by oxidative stress and infections. PMID:26783712

Evaluation of diclofenac prodrugs for enhancing transdermal delivery.

PubMed

Lobo, Shabbir; Li, Henan; Farhan, Nashid; Yan, Guang

2014-03-01

Abstract Objective: The purpose of this study was to evaluate the approach of using diclofenac acid (DA) prodrugs for enhancing transdermal delivery. Methanol diclofenac ester (MD), ethylene glycol diclofenac ester (ED), glycerol diclofenac ester (GD) and 1,3-propylene glycol diclofenac ester (PD) were synthesized and evaluated for their physicochemical properties such as solubilities, octanol/water partition coefficients, stratum corneum/water partition coefficients, hydrolysis rates and bioconversion rates. In vitro fluxes across human epidermal membrane (HEM) in the Franz diffusion cell were determined on DA-, MD-, ED-, GD- and PD-saturated aqueous solutions. The formation of GD and ED led to the prodrugs with higher aqueous solubilities and lower partition coefficients than those of the parent drug. Prodrugs with improved aqueous solubility showed better fluxes across HEM in aqueous solution than that of the parent drug, with GD showing the highest aqueous solubility and also the highest flux. There is a linear relationship between the aqueous solubility and flux for DA, ED and PD, but GD and MD deviated from the linear line. Diclofenac prodrugs with improved hydrophilicity than the parent drug could be utilized for enhancing transdermal diclofenac delivery.

Continuum Model for Decontamination of Chemical Warfare Agent from a Rubbery Polymer using the Maxwell-Stefan Formulation

NASA Astrophysics Data System (ADS)

Varady, Mark; Bringuier, Stefan; Pearl, Thomas; Stevenson, Shawn; Mantooth, Brent

Decontamination of polymers exposed to chemical warfare agents (CWA) often proceeds by application of a liquid solution. Absorption of some decontaminant components proceed concurrently with extraction of the CWA, resulting in multicomponent diffusion in the polymer. In this work, the Maxwell-Stefan equations were used with the Flory-Huggins model of species activity to mathematically describe the transport of two species within a polymer. This model was used to predict the extraction of the nerve agent O-ethyl S-[2(diisopropylamino)ethyl] methylphosphonothioate (VX) from a silicone elastomer into both water and methanol. Comparisons with experimental results show good agreement with minimal fitting of model parameters from pure component uptake data. Reaction of the extracted VX with sodium hydroxide in the liquid-phase was also modeled and used to predict the overall rate of destruction of VX. Although the reaction proceeds more slowly in the methanol-based solution compared to the aqueous solution, the extraction rate is faster due to increasing VX mobility as methanol absorbs into the silicone, resulting in an overall faster rate of VX destruction.

Preparation and physicochemical characterization of 5 niclosamide solvates and 1 hemisolvate.

PubMed

van Tonder, Elsa C; Mahlatji, Mabatane D; Malan, Sarel F; Liebenberg, Wilna; Caira, Mino R; Song, Mingna; de Villiers, Melgardt M

2004-02-23

The purpose of the study was to characterize the physicochemical, structural, and spectral properties of the 1:1 niclosamide and methanol, diethyl ether, dimethyl sulfoxide, N,N' dimethylformamide, and tetrahydrofuran solvates and the 2:1 niclosamide and tetraethylene glycol hemisolvate prepared by recrystallization from these organic solvents. Structural, spectral, and thermal analysis results confirmed the presence of the solvents and differences in the structural properties of these solvates. In addition, differences in the activation energy of desolvation, batch solution calorimetry, and the aqueous solubility at 25 degrees C, 24 hours, showed the stability of the solvates to be in the order: anhydrate > diethyl ether solvate > tetraethylene glycol hemisolvate > methanol solvate > dimethyl sulfoxide solvate > N,N' dimethylformamide solvate. The intrinsic and powder dissolution rates of the solvates were in the order: anhydrate > diethyl ether solvate > tetraethylene glycol hemisolvate > N,N' dimethylformamide solvate > methanol solvate > dimethyl sulfoxide solvate. Although these nonaqueous solvates had higher solubility and dissolution rates than the monohydrous forms, they were unstable in aqueous media and rapidly transformed to one of the monohydrous forms.

Photostability of 6-MAM and morphine exposed to controlled UV irradiation in water and methanol solution: HRMS for the characterization of transformation products and comparison with the dry state.

PubMed

Miolo, Giorgia; Tucci, Marianna; Mazzoli, Alessandra; Ferrara, Santo Davide; Favretto, Donata

2016-07-15

The UVA and UVB light-induced behaviour of 6-monoacetylmorphine (6-MAM) and morphine, the main metabolites of heroin, was studied in methanol, aqueous solution and in the dry state. UVA and UVB irradiations were performed for different times (radiant energies of 20-300J/cm(2)). UV spectra of irradiated samples were compared with samples kept in the dark. To estimate the extent of photolysis, positive ion electrospray ionization experiments were performed on the irradiated samples by LC-HRMS. Tentative identification of photoproducts was performed on the basis of their elemental formula as calculated by HRMS results. Morphine and 6-MAM demonstrated to be quite stable under UVA light but very sensitive to UVB irradiation. In methanol solutions they undergo a similar pattern, both reaching 90% photodegradation after 100J/cm(2) of UVB, with a slightly faster kinetic for morphine at lower doses. In water, the yields of photodegradation are nearly one third lower than in methanol. In the solid state, the yield of photodegradation is lower than in solution. The structures of some UVB-induced degradation products are proposed. Photoaddition of the solvent and photooxidation seem the main pathways of phototransformation of these molecules. Moreover, both compounds revealed to generate singlet oxygen under UVB exposure. Copyright © 2016 Elsevier B.V. All rights reserved.

Separation of nitrogen heterocyclic compounds from model coal tar fraction by solvent extraction

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

Kim, S.J.; Chun, Y.J.

2005-07-01

The separation of four kinds of nitrogen heterocyclic compounds (NHCs) from a model mixture comprising NHCs (indole (In), quinoline (Q), iso-quinoline (iQ), quinaldine (Qu)), three kinds of bicyclic aromatic compounds (BACs; 1-methyl-naphthalene (IMN), 2-methyl naphthalene (2MN), dimethylnaphthalene (DMN)), biphenyl (Bp) and phenyl ether (Pe) was examined by a solvent extraction. The model mixture used as a raw material of this work was prepared according to the components and compositions contained in coal tar fraction (the temperature ranges of fraction: 240-265{sup o}C). An aqueous solution of methanol, ethanol, iso-propyl alcohol, N,N-dimethyl acetamide, DMF, formamide, N-methylformamide/methanol, and formamide/methanol were used as solvents.more » An aqueous solution of formamide was found suitable for separating NHCs contained in coal tar fraction based on distribution coefficient and selectivity. The effect of operation factors on separating NHCs was investigated by the distribution equilibrium using an aqueous solution of formamide. Increasing the operation temperature and the volume ratio of solvent to feed at initial (S/F)(o) resulted in improving the distribution coefficients of each NHC, but increasing the volume fraction of water in the solvent at initial (y(w,O)) resulted in deteriorating the distribution coefficients of each NHC. With increasing y(w,O) and (S/F)(o), the selectivities of each NHC in reference to DMN increased. Increase in operation temperature resulted in decrease in selectivities of each NHC in reference to DMN. At an experimental condition fixed, the sequence of the distribution coefficient and selectivity in reference to DMN for each NHC was In {gt} iQ {gt} Q {gt} Qu, and also the sequence of the distribution coefficient for each BAC was IMN {gt} 2MN {gt} DMN. The sequence of the distribution coefficient for entire compounds analyzed by this work was In {gt} iQ {gt} Q {gt} Qu {gt} BP {gt} 1MN {gt} 2MN {gt} Pe {gt} DMN.« less

Methanol and the productivity of tropical crops

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

Ferguson, T.U.

1995-12-31

Studies are being conducted in Trinidad and Tobago, St. Lucia and St. Kitts/Nevis to determine the effect of aqueous solutions of methanol on the growth and yield of a wide range of vegetable, field and perennial crops. The paper presents a summary of results to data for ten of the crops studied. Six of these crops, lettuce, sweet pepper, tomato, mango and breadfruit, have shown significant increases in growth or yield with methanol application, while others such as pigeon pea, rice, banana and cocoa have shown more limited responses. There appears to be some potential for the use of methanolmore » in tropical crop production but further studies are required before this apparent potential can be harnessed.« less

Preparation of fatty acid methyl esters for gas-liquid chromatography[S

PubMed Central

Ichihara, Ken'ichi; Fukubayashi, Yumeto

2010-01-01

A convenient method using commercial aqueous concentrated HCl (conc. HCl; 35%, w/w) as an acid catalyst was developed for preparation of fatty acid methyl esters (FAMEs) from sterol esters, triacylglycerols, phospholipids, and FFAs for gas-liquid chromatography (GC). An 8% (w/v) solution of HCl in methanol/water (85:15, v/v) was prepared by diluting 9.7 ml of conc. HCl with 41.5 ml of methanol. Toluene (0.2 ml), methanol (1.5 ml), and the 8% HCl solution (0.3 ml) were added sequentially to the lipid sample. The final HCl concentration was 1.2% (w/v). This solution (2 ml) was incubated at 45°C overnight or heated at 100°C for 1–1.5 h. The amount of FFA formed in the presence of water derived from conc. HCl was estimated to be <1.4%. The yields of FAMEs were >96% for the above lipid classes and were the same as or better than those obtained by saponification/methylation or by acid-catalyzed methanolysis/methylation using commercial anhydrous HCl/methanol. The method developed here could be successfully applied to fatty acid analysis of various lipid samples, including fish oils, vegetable oils, and blood lipids by GC. PMID:19759389

H2 Production Under Visible Light Irradiation from Aqueous Methanol Solution on CaTiO3:Cu Prepared by Spray Pyrolysis

NASA Astrophysics Data System (ADS)

Lim, Sung Nam; Song, Shin Ae; Jeong, Yong-Cheol; Kang, Hyun Woo; Park, Seung Bin; Kim, Ki Young

2017-10-01

Perovskite-type photocatalysts of CaCu x Ti1- x O3 (0 ≤ x ≤ 0.02) powder were prepared by spray pyrolysis of aqueous solution or aqueous solution with polymeric additive. The effects of the amount of copper ions doped in the photocatalyst and the precursor type on the photocatalytic activity under visible-light irradiation were investigated. The crystal structure, oxidation state, and light adsorption properties of the prepared photocatalysts were analyzed using x-ray diffraction, x-ray photoelectron spectroscopy, and diffuse reflectance spectroscopy, respectively. The doping of copper ions in CaTiO3 allowed visible-light absorption owing to a narrowing of the band gap energy of the host material through the formation of a new donor level for copper ions. Among the doped samples prepared from the aqueous precursor, CaTiO3 doped with 1 mol.% copper ions had the highest hydrogen evolution rate (140.7 μmol g-1 h-1). Notably, the hydrogen evolution rate of the photocatalyst doped with 1 mol.% copper ions prepared from the aqueous precursor with polymeric additive (295.0 μmol g-1 h-1) was two times greater than that prepared from the aqueous precursor, due to the morphology effect.

The adsorption properties of short chain alcohols and Triton X-100 mixtures at the water-air interface.

PubMed

Zdziennicka, Anna

2009-07-15

The adsorption behaviour at the water-air interface of aqueous solutions of Triton X-100 and methanol (ethanol) mixtures at constant Triton X-100 (TX-100) concentration equal to 10(-7), 10(-6), 10(-5), 10(-4), 6x10(-4) and 10(-3)M, respectively, in a wide range of alcohol concentration was investigated by surface tension measurements of solutions. The obtained values of the surface tension of aqueous solutions of "pure" methanol and ethanol and their mixtures with TX-100, as well as the values of propanol solutions and their mixtures with TX-100 as a function of alcohol concentration taken from the literature were compared with those calculated from the Szyszkowski, Connors and Fainerman and Miller equations. On the basis of this comparison it was stated that these equations can be useful for description of the solution surface tension in the wide range of alcohol concentration, but only at the concentrations of Triton X-100 corresponding to its unsaturated layer in the absence of alcohol. It was also stated that the Connors equation is more adequate for concentrated aqueous organic solutions. The measured values of the surface tension were used in the Gibbs equation to determine the surface excess concentration of Triton X-100 and alcohol. Next, on the basis of Gibbs adsorption isotherms those of Guggenheim and Adam and real adsorption isotherms were established. From the obtained adsorption isotherms it results that alcohol influences the shape of TX-100 isotherms in the whole range of alcohol and TX-100 concentration, but TX-100 influences the alcohol isotherms only at TX-100 concentration at which the saturated monolayer at the solution-air interface is formed in the absence of alcohol. This conclusion was confirmed by analysis of the composition of the surface layer in comparison to the composition of the bulk phase in the equilibrium state.

Stability of natamycin and its cyclodextrin inclusion complexes in aqueous solution.

PubMed

Koontz, John L; Marcy, Joseph E; Barbeau, William E; Duncan, Susan E

2003-11-19

Aqueous solutions of natamycin and its beta-cyclodextrin (beta-CD), hydroxypropyl beta-cyclodextrin, and gamma-cyclodextrin (gamma-CD) inclusion complexes were completely degraded after 24 h of exposure to 1000 lx fluorescent lighting at 4 degrees C. After 14 days of storage in darkness at 4 degrees C, 92.2% of natamycin remained in active form. The natamycin:beta-CD complex and natamycin:gamma-CD complex were significantly more stable (p < 0.05) than natamycin in its free state in aqueous solutions stored in darkness at 4 degrees C. Clear poly(ethylene terephthalate) packaging with a UV light absorber allowed 85.0% of natamycin to remain after 14 days of storage under 1000 lx fluorescent lighting at 4 degrees C. Natamycin:cyclodextrin complexes can be dissociated for analysis in methanol/water/acetic acid, 60:40:5, v/v/v. Natamycin and its complexes in dissociated form were quantified by reverse phase HPLC with detection by photodiode array at 304 nm.

Studies of Partial Molar Volumes of Some Narcotic-Analgesic Drugs in Aqueous-Alcoholic Mixtures at 25°C

NASA Astrophysics Data System (ADS)

Sharma, Poonam; Chauhan, S.; Syal, V. K.; Chauhan, M. S.

2008-04-01

Partial molar volumes of the drugs Parvon Spas, Parvon Forte, Tramacip, and Parvodex in aqueous mixtures of methanol (MeOH), ethanol (EtOH), and propan-1-ol (1-PrOH) have been determined. The data have been evaluated using the Masson equation. The parameters, apparent molar volumes {(φ_v)}, partial molar volumes {(φ_v0)}, and S v values (experimental slopes) have been interpreted in terms of solute solvent interactions. In addition, these studies have also been extended to determine the effect of these drugs on the solvation behavior of an electrolyte (sodium chloride), a surfactant (sodium dodecyl sulfate), and a non-electrolyte (sucrose). It can be inferred from these studies that all drug cations can be regarded as structure makers/promoters due to hydrophobic hydration. Furthermore, the results are correlated to understand the solution behavior of drugs in aqueous-alcoholic systems, as a function of the nature of the alcohol and solutes.

Hair decontamination procedure prior to multi-class pesticide analysis.

PubMed

Duca, Radu-Corneliu; Hardy, Emilie; Salquèbre, Guillaume; Appenzeller, Brice M R

2014-06-01

Although increasing interest is being observed in hair analysis for the biomonitoring of human exposure to pesticides, some limitations still have to be addressed for optimum use of this matrix in that specific context. One main possible issue concerns the need to differentiate chemicals biologically incorporated into hair from those externally deposited on hair surface from contaminated air or dust. The present study focuses on the development of a washing procedure for the decontamination of hair before analysis of pesticides from different chemical classes. For this purpose, three different procedures of artificial contamination (with silica, cellulose, and aqueous solution) were used to simulate pesticides deposition on hair surface. Several washing solvents (four organic: acetone, dichloromethane, methanol, acetonitrile; and four aqueous: water, phosphate buffer, shampoo, sodium dodecylsulfate) were evaluated for their capacity to remove artificially deposited pesticides from hair surface. The most effective washing solvents were sodium dodecylsulfate and methanol for aqueous and organic solvents, respectively. Moreover, after a first washing with sodium dodecylsulfate or methanol, the majority of externally deposited pesticides was removed and a steady-state was reached since significantly lower amounts were removed by additional second and third washings. Finally, the effectiveness of a decontamination procedure comprising washing with sodium dodecylsulfate and methanol was successively demonstrated. In parallel, it was determined that the final procedure did not affect the chemicals biologically incorporated, as hair strands naturally containing pesticides were used. Such a procedure appears to remove in one-shot the fraction of chemicals located on hair surface and does not require repeated washing steps. Copyright © 2014 John Wiley & Sons, Ltd.

Sedative and Hypnotic Activities of the Methanolic and Aqueous Extracts of Lavandula officinalis from Morocco

PubMed Central

Alnamer, Rachad; Alaoui, Katim; Bouidida, El Houcine; Benjouad, Abdelaziz; Cherrah, Yahia

2012-01-01

We evaluate the sedative and hypnotic activities of the methanolic and aqueous extract of Lavandula officinalis L. on central nervous system (CNS). In this study, the effect of the methanolic and aqueous extracts of this plant was investigated in a battery of behavioural models in mice. Stems and flowers of Lavandula officinalis L. have several therapeutic applications in folk medicine in curing or managing a wide range of diseases, including insomnia. The methanolic extract produced significant sedative effect at the doses of 200, 400, and 600 mg/kg (by oral route), compared to reference substance diazepam (DZP), and an hypnotic effect at the doses of 800 and 1000 mg/kg while the treatment of mice with the aqueous extract at the doses of 200 and 400 mg/kg via oral pathway significantly reduced in both the reestablishment time and number of head dips during the traction and hole-board tests. In conclusion, these results suggest that the methanolic and aqueous extracts of Lavandula officinalis possess potent sedative and hypnotic activities, which supported its therapeutic use for insomnia. PMID:22162677

Preparation of polyurethane foams using fractionated products in liquefied wood

Treesearch

Junming Xu; Jianchun Jiang; Chung-Yun Hse; Todd F. Shupe

2014-01-01

Liquefaction of sawdust was studied using glycerol and methanol as mix solvents. A new bio-polyol product consisting of high purity multi-hydroxy compounds was obtained by precipitation of the hydrophobic organics from the liquefied product in an aqueous solution. As identified by GC-MS, the dominate components in bio-polyol were glycerol, glycerol derivatives, and...

Terahertz sensing of highly absorptive water-methanol mixtures with multiple resonances in metamaterials.

PubMed

Chen, Min; Singh, Leena; Xu, Ningning; Singh, Ranjan; Zhang, Weili; Xie, Lijuan

2017-06-26

Terahertz sensing of highly absorptive aqueous solutions remains challenging due to strong absorption of water in the terahertz regime. Here, we experimentally demonstrate a cost-effective metamaterial-based sensor integrated with terahertz time-domain spectroscopy for highly absorptive water-methanol mixture sensing. This metamaterial has simple asymmetric wire structures that support multiple resonances including a fundamental Fano resonance and higher order dipolar resonance in the terahertz regime. Both the resonance modes have strong intensity in the transmission spectra which we exploit for detection of the highly absorptive water-methanol mixtures. The experimentally characterized sensitivities of the Fano and dipole resonances for the water-methanol mixtures are found to be 160 and 305 GHz/RIU, respectively. This method provides a robust route for metamaterial-assisted terahertz sensing of highly absorptive chemical and biochemical materials with multiple resonances and high accuracy.

Simultaneous determination of bromhexine hydrochloride and methyl and propyl p-hydroxybenzoate and determination of dextromethorphan hydrobromide in cough-cold syrup by high-performance liquid chromatography.

PubMed

Rauha, J P; Salomies, H; Aalto, M

1996-11-01

Liquid chromatographic methods were developed for the determination of bromhexine hydrochloride, methyl p-hydroxybenzoate and propyl p-hydroxybenzoate (method A) and dextromethorphan hydrobromide (method B) in cough-cold syrup formulations. Reversed-phase analytical columns (150 mm x 3.9 mm i.d.) were used with (A) C18 and (B) phenyl as stationary phases and mixtures of (A) acetonitrile and aqueous 15 mM triethylamine solution (43:57) and (B) methanol and aqueous 3% ammonium formate buffer solution (53:47) as mobile phases at a flow rate of 1.0 ml min-1. Both aqueous components were adjusted to pH 3.9. UV detection of analytes was at (A) 245 nm and (B) 278 nm. In both methods, the time required for an HPLC run giving good separations and recoveries was less than 8 min.

Hemin-utilizing G-quadruplex DNAzymes are strongly active in organic co-solvents.

PubMed

Canale, Thomas D; Sen, Dipankar

2017-05-01

The widespread use of organic solvents in industrial processes has focused in recent years on the utility of "green" solvents - those with less harmful environmental, health, and safety properties - such as methanol and formamide. However, protein enzymes, regarded as green catalysts, are often incompatible with organic solvents. Herein, we have explored the oxidative properties of a Fe(III)-heme, or hemin, utilizing catalytic DNA (heme·DNAzyme) in different green solvent-water mixtures. We find that the peroxidase and peroxygenase activities of the heme·DNAzyme are strongly enhanced in 20-30% v/v methanol or formamide, relative to water alone. Protic solvent content of >30% v/v gradually diminishes heme·DNAzyme catalytic activity; however, the heme·DNAzyme is still active in as high as 80% v/v methanol. In contrast to protic solvents, aqueous dimethylformamide solutions largely inhibit heme·DNAzyme activity. In view of the strong catalytic activity of heme·DNAzyme in aqueous methanol, we were able to determine that a 60% v/v methanol-water mixture gives the most optimal yield of the dibenzothiophene sulfoxide (DBTO) oxidation product of petroleum-derived dibenzothiophene (DBT). The high product yield reflects both DNAzyme catalysis and a high substrate availability. Overall, these results emphasize the excellent promise of G-quadruplex forming DNA catalysts in application to "greener" industrial chemistry. This article is part of a Special Issue entitled "G-quadruplex" Guest Editor: Dr. Concetta Giancola and Dr. Daniela Montesarchio. Copyright © 2016 Elsevier B.V. All rights reserved.

Viscosity of Associated Mixtures Approximated by the Grunberg-Nissan Model

NASA Astrophysics Data System (ADS)

Marczak, W.; Adamczyk, N.; Łężniak, M.

2012-04-01

Previous experiments demonstrated that microheterogeneities occur in liquid systems (2-methylpyridine or 2,6-dimethylpyridine) + water. They are most probably due to the association of the hydrates through hydrogen bonds between water molecules. Substitution of methanol for water causes that the mixtures become homogenous. The results of viscometric studies reported in this study confirmed that the molecular clusters in aqueous solutions are much larger than the complexes occurring in the methanolic systems. Taking into consideration "kinetic entities" rather than monomeric molecules, the dependence of viscosity on concentration and temperature have been satisfactorily approximated by the Grunberg-Nissan relation with two adjustable coefficients. The kinetic entities were trimers of water, dimers of methanol, and monomeric amines. The same approach proved to be valid for the activation energy of viscous flow as well.

Comparative Study of Erythrina indica Lam. (Febaceae) Leaves Extracts for Antioxidant Activity

PubMed Central

Sakat, SS; Juvekar, AR

2010-01-01

The present study was designed to investigate the antioxidant activity of aqueous and methanol extracts of Erythrina indica Lam leaves by in vitro methods viz. 1, 1-Diphenyl-2-Picrylhydrazyl, nitric oxide radical scavenging activity, and inhibition of lipid peroxidation by thiobarbituric acid reactive substances (TBARS) method on isolated rat liver tissues. Quantitative analysis of antioxidative components like total amount of phenolics, flavonoids, and flavonols were estimated using the spectrophotometric method. Linear regression analysis was used to calculate the IC50 value. Results showed that the aqueous and methanol extracts exhibited significant DPPH radicals scavenging activity with an IC50 value 342.59 ± 19.59, 283.24 ± 12.28 µg/mL respectively. Nitric oxide radicals were significantly scavenged by the aqueous and methanol extracts (IC50 = 250.12 ± 10.66; 328.29 ± 3.74 µg/mL). Lipid peroxidation induced by the Fe2+ was inhibited by the aqueous extract with low IC50 value (97.29 ± 2.05 µg/mL) as compared to methanol extract (IC50 = 283.74 ± 5.70 µg/mL). Both the extracts were exhibited similar quantities of total phenolics. Total flavonoids were found to be in higher quantities than total flavonols in aqueous extract as compared to methanol extract. From the results, it is concluded that the aqueous and methanol extracts of E. indica leaves possesses significant antioxidant activity that may be due to the presence of flavonoids and related polyphenolic compounds. PMID:21331194

Solution Dependence of the Collisional Activation of Ubiquitin [M+7H]7+ Ions

PubMed Central

Shi, Huilin; Atlasevich, Natalya; Merenbloom, Samuel I.; Clemmer, David E.

2014-01-01

The solution dependence of gas-phase unfolding for ubiquitin [M+7H]7+ ions has been studied by ion mobility spectrometry-mass spectrometry (IMS-MS). Different acidic water:methanol solutions are used to favor the native (N), more helical (A), or unfolded (U) solution states of ubiquitin. Unfolding of gas-phase ubiquitin ions is achieved by collisional heating and newly formed structures are examined by IMS. With an activation voltage of 100 V, a selected distribution of compact structures unfolds, forming three resolvable elongated states (E1-E3). The relative populations of these elongated structures depend strongly on the solution composition. Activation of compact ions from aqueous solutions known to favor N-state ubiquitin produces mostly the E1 type elongated state, whereas, activation of compact ions from methanol containing solutions that populate A-state ubiquitin favors the E3 elongated state. Presumably, this difference arises because of differences in precursor ion structures emerging from solution. Thus, it appears that information about solution populations can be retained after ionization, selection, and activation to produce the elongated states. These data as well as others are discussed. PMID:24658799

In vitro antibacterial activity and acute toxicity studies of aqueous-methanol extract of Sida rhombifolia Linn. (Malvaceae).

PubMed

Assam, Assam J P; Dzoyem, J P; Pieme, C A; Penlap, V B

2010-07-27

Many bacteria among the Enterobacteria family are involved in infectious diseases and diarrhoea. Most of these bacteria become resistant to the most commonly used synthetic drugs in Cameroon. Natural substances seem to be an alternative to this problem. Thus the aim of this research was to investigate the in vitro antibacterial activity of the methanol and aqueous-methanol extracts of Sida rhombifolia Linn (Malvaceae) against seven pathogenic bacteria involved in diarrhoea. Acute toxicity of the most active extract was determined and major bioactive components were screened. The agar disc diffusion and the agar dilution method were used for the determination of inhibition diameters and the Minimum Inhibitory Concentration (MICs) respectively. The acute toxicity study was performed according WHO protocol. The aqueous-methanol extract (1v:4v) was the most active with diameters of inhibition zones ranging from 8.7 - 23.6 mm, however at 200 microg/dic this activity was relatively weak compared to gentamycin. The MICs of the aqueous-methanol extract (1v:4v) varied from 49.40 to 78.30 microg/ml. Salmonella dysenteriae was the most sensitive (49.40 microg/ml). For the acute toxicity study, no deaths of rats were recorded. However, significant increase of some biochemical parameters such as aspartate amino-transferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) and creatinine (CRT) were found. The phytochemical analysis of the aqueous methanol extract indicated the presence of tannins, polyphenols, alkaloids, glycosides, flavonoids and saponins The results showed that the aqueous-methanol extract of S. rhombifolia exhibited moderate antibacterial activity. Some toxic effects were found when rats received more than 8 g/kg bw of extract.

In vitro antibacterial activity and acute toxicity studies of aqueous-methanol extract of Sida rhombifolia Linn. (Malvaceae)

PubMed Central

2010-01-01

Background Many bacteria among the Enterobacteria family are involved in infectious diseases and diarrhoea. Most of these bacteria become resistant to the most commonly used synthetic drugs in Cameroon. Natural substances seem to be an alternative to this problem. Thus the aim of this research was to investigate the in vitro antibacterial activity of the methanol and aqueous-methanol extracts of Sida rhombifolia Linn (Malvaceae) against seven pathogenic bacteria involved in diarrhoea. Acute toxicity of the most active extract was determined and major bioactive components were screened. Methods The agar disc diffusion and the agar dilution method were used for the determination of inhibition diameters and the Minimum Inhibitory Concentration (MICs) respectively. The acute toxicity study was performed according WHO protocol. Results The aqueous-methanol extract (1v:4v) was the most active with diameters of inhibition zones ranging from 8.7 - 23.6 mm, however at 200 μg/dic this activity was relatively weak compared to gentamycin. The MICs of the aqueous-methanol extract (1v:4v) varied from 49.40 to 78.30 μg/ml. Salmonella dysenteriae was the most sensitive (49.40 μg/ml). For the acute toxicity study, no deaths of rats were recorded. However, significant increase of some biochemical parameters such as aspartate amino-transferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) and creatinine (CRT) were found. The phytochemical analysis of the aqueous methanol extract indicated the presence of tannins, polyphenols, alkaloids, glycosides, flavonoids and saponins Conclusion The results showed that the aqueous-methanol extract of S. rhombifolia exhibited moderate antibacterial activity. Some toxic effects were found when rats received more than 8 g/kg bw of extract. Antibacterial; Enterobacteria; Acute toxicity; Phytochemical analysis PMID:20663208

Determination of 10 sulfonamide residues in meat samples by liquid chromatography with ultraviolet detection.

PubMed

Di Sabatino, Marcello; Di Pietra, Anna Maria; Benfenati, Luigi; Di Simone, Bruno

2007-01-01

A liquid chromatography (LC) method is described for the simultaneous determination of 10 commonly used sulfonamide drug residues in meat. The 10 sulfonamide drugs of interest were sulfadiazine, sulfathiazole, sulfamerazine, sulfadimidine, sulfamethizole, sulfamonomethoxine, sulfachloropyridazine, sulfadoxine, sulfadimethoxine, and sulfaquinoxaline. The residues were extracted with acetone-chloroform (1 + 1). Sulfonamides were quantitatively retained in the extracting solution and afterwards eluted from a cation-exchanger solid-phase extraction cartridge with a solution of methanol-aqueous ammonia. The solution was dried, reconstituted with 5 mL methanol and filtered before analysis by LC-ultraviolet using a C18 column with a mobile phase gradient of potassium dihydrogen phosphate buffer, pH 2.5, and methanol-acetonitrile (30 + 70, v/v). The method was applied to cattle, swine, chicken, and sheep muscle tissues. The validation was performed with a fortified cattle meat sample at level of 100 ppb, which is the administrative maximum residue limit for sulfonamides in the European Union. The limit of quantitation for all sulfonamides was between 3 and 14 ppb. Recovery was evaluated for different meat matrixes. The mean recovery values were between 66.3% for pork meat samples and 71.5% for cattle meat samples.

[Intersection point rule for the retention value with mobile phase composition and boiling point of the homologues and chlorobenzenes in soil leaching column chromatography].

PubMed

Xu, F; Liang, X; Lin, B; Su, F

1999-03-01

Based on the linear retention equation of the logarithm of the capacity factor (logk') vs. the methanol volume fraction (psi) of aqueous binary mobile phase in soil leaching column chromatography, the intersection point rule for the logk' of homologues and weak polar chlorobenzenes, with psi, as well as with boiling point, has been derived due to existence of the similar interactions among solutes of the same series, stationary phase (soil) and eluent (methanol-water). These rules were testified by experimental data of homologues (n-alkylbenzenes, methylbenzenes) and weak polar chlorobenzenes.

Evaluation of Anti-Inflammatory Activity and In-vitro Antioxidant Activity of Indian Mistletoe, the Hemiparasite Dendrophthoe falcate L. F. (Loranthaceae)

PubMed Central

Patil, Satish; Anarthe, Sneha; Jadhav, Ram; Surana, Sanjay

2011-01-01

Methanolic and aqueous extracts of Dendrophthoe falcata Linn. leaves which belongs to the Loranthaceae family, were evaluated through DPPH (1, 1-diphenyl -2-picryl-hydrazyl), antilipid peroxidation and nitric oxide scavenging methods to assess the antioxidant activity. Methanolic and aqueous extracts of Dendrophthoe falcata leaves were also evaluated for their anti-inflammatory activity by carrageenan and cotton pellet induced granuloma tests for their effect on the acute and chronic phase inflammation models in rats. It was found that the methanolic extract of Dendrophthoe falcata leaves demonstrates potent antioxidant activity as compared to aqueous extraction of Dendrophthoe falcata leaves for DPPH (1, 1-diphenyl-2-picryl-hydrazyl) radical scavenging, anti-lipid peroxidation and nitric oxide scavenging activity respectively (having IC50 value 77.8, 79.36 and 86.2, 144, 87, 104). The maximum inhibition for aqueous extract of Dendrophthoe falcata leaves (30.95%) and methanolic extract of Dendrophthoe falcata leaves (23.41%) were obtained at a dose of 300 mg/Kg after 4h of drug treatment in carrageenan induced paw edema, whereas diclofenac sodium (standard drug) produced 42.85% inhibition. In the chronic model (cotton pellet induced granuloma), aqueous extracts of Dendrophthoe falcata leaves and methanolic extracts of Dendrophthoe falcata leaves (at doses of 300 mg/Kg), phenylbutazone as standard drug showed decreased formation of granuloma tissue by 51%, 48%, 53% respectively. In addition, the total phenolic and flavonoid content of aqueous extracts of Dendrophthoe falcata leaves and methanolic extracts of Dendrophthoe falcata leaves were found to be 2.12 % w/w, 4.39 % w/w, 0.31 mg/g and 0.85 mg/g respectively. Thus the results indicate that methanolic and aqueous extracts of Dendrophthoe falcataleaves on animal models have potent anti-inflammatory and in-vitro antioxidant effects. PMID:24250351

Preparation and Characterization of Zirconia-Coated Nanodiamonds as a Pt Catalyst Support for Methanol Electro-Oxidation

PubMed Central

Lu, Jing; Zang, Jianbing; Wang, Yanhui; Xu, Yongchao; Xu, Xipeng

2016-01-01

Zirconia-coated nanodiamond (ZrO2/ND) electrode material was successfully prepared by one-step isothermal hydrolyzing from ND-dispersed ZrOCl2·8H2O aqueous solution. High-resolution transmission electron microscopy reveals that a highly conformal and uniform ZrO2 shell was deposited on NDs by this simple method. The coating obtained at 90 °C without further calcination was mainly composed of monoclinic nanocrystalline ZrO2 rather than common amorphous Zr(OH)4 clusters. The ZrO2/NDs and pristine ND powder were decorated with platinum (Pt) nanoparticles by electrodeposition from 5 mM chloroplatinic acid solution. The electrochemical studies indicate that Pt/ZrO2/ND catalysts have higher electrocatalytic activity and better stability for methanol oxidation than Pt/ND catalysts in acid. PMID:28335361

Solvent effects and polymorphic transformation of organic nonlinear optical crystal L-pyroglutamic acid in solution growth processes . I. Solvent effects and growth morphology

NASA Astrophysics Data System (ADS)

Wang, W. S.; Aggarwal, M. D.; Choi, J.; Gebre, T.; Shields, Angela D.; Penn, Benjamin G.; Frazier, Donald O.

1999-03-01

Single crystals of a new promising nonlinear optical material for the tunable UV harmonic generation, L-pyroglutamic acid 60×20×20 mm 3 in size were obtained from aqueous solution by using the temperature-lowering method. Solubility of L-pyroglutamic acid in different solvents was measured. The single crystals showed different morphological characteristics and growth rate in different solvents with different crystallographic orientations. Methanol or ethanol solutions yielded needle-like crystals. In mixed solution such as methanol/H 2O or ethanol/ H 2O plate-like crystals with a thickness in the direction [0 1 0] were observed. The water as a good solvent, however, produced long prism-like crystals. The two polymorphs of L-pyroglutamic acid (α and β phases) were found for the first time. The growth shapes of α-phase is mainly a prism and β phases is a rhombic plate.The growth rate of α and β phases is mainly a function of the supersaturation of the L-pyroglutamic acid in solution.

Traditional preparation of Phaleria nisidai, a Palauan tea, reduces exposure to toxic daphnane-type diterpene esters while maintaining immunomodulatory activity.

PubMed

Kulakowski, Daniel; Kitalong, Christopher; Negrin, Adam; Tadao, Van-Ray; Balick, Michael J; Kennelly, Edward J

2015-09-15

The leaves of Phaleria nisidai Kaneh. (Thymelaeaceae) are brewed into a tea commonly used as a tonic, strengthening beverage and immune enhancer in Palau, Micronesia. Recently, the leaves of P. nisidai have been shown to contain toxic daphnane diterpene esters which may pose a public health threat to Palauans. This project documents the use frequency, preparation and side effects of P. nisidai. The content of daphnane diterpene esters in aqueous and methanol extracts and infusions prepared by healers in Palau is compared to assess the risk of daphnane ingestion associated with traditional consumption. Quantitative results are correlated with an in vitro assessment of the immunomodulating activity of the extracts. Research participants, comprising traditional healers and laypeople, were interviewed concerning use patterns and side effects of P. nisidai. Several traditional healers prepared and provided boiled tea samples for chemical analysis. Leaves were collected and methanolic and aqueous extractions were prepared in the laboratory. Peripheral blood mononuclear cells (PBMCs) were cultured with various concentrations of methanol and aqueous leaf extracts and their output of IFNγ was measured using ELISA. Cell proliferation was also assessed using the MTT assay. The concentration of selected daphnane diterpene esters in healer-prepared infusions, lab methanol and lab aqueous extracts was quantified using ultraperformance liquid chromatography-mass spectrometry-triple quadrupole detection (UPLC-MS-TQD). Through structured interviews it was determined that P. nisidai tea was used frequently, with many participants drinking it daily. The reported side effects were mild, and with the exception of diarrhea (n=2), no side effect was mentioned more than once. Methanol extracts contained 4.0μg simplexin, 17.6μg acetoxyhuratoxin and 2.3μg huratoxin per g dry leaf material. In traditional water infusions provided by healers and in standardized lab-prepared aqueous extracts all three compounds were below the limit of detection (16.3ng/mL) using our UPLC-MS-TQD method. Methanol and aqueous extracts increased the release of IFNγ by PBMCs (p<0.05); however, methanol extracts were significantly more active than aqueous extracts (p<0.05). Methanol and aqueous extracts significantly increased proliferation of PBMCs, causing at least 60% more cell proliferation than negative control (p<0.05). The presence of daphnane diterpene esters in a frequently consumed traditional beverage was initially viewed as a public health concern, though interview data reveal that Palauans do not observe toxicity or side effects associated with their use of P. nisidai tea. Concurrently, daphnanes are present in methanolic extracts but not detected in aqueous preparations indicating that the traditional method of preparation avoids the extraction of these potentially toxic compounds, while still maintaining immunostimulant activity. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Adsorption mechanism in RPLC. Effect of the nature of the organic modifier

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

Gritti, Fabrice; Guiochon, Georges A

2005-07-01

The adsorption isotherms of phenol and caffeine were acquired by frontal analysis on two different adsorbents, Kromasil-C{sub 18} and Discovery-C{sub 18}, with two different mobile phases, aqueous solutions of methanol (MeOH/H{sub 2}O = 40/60 and 30/70, v/v) and aqueous solutions of acetonitrile (MeCN/H{sub 2}O = 30/70 and 20/80, v/v). The adsorption isotherms are always strictly convex upward in methanol/water solutions. The calculations of the adsorption energy distribution confirm that the adsorption data for phenol are best modeled with the bi-Langmuir and the tri-Langmuir isotherm models for Kromasil-C{sub 18} and Discovery-C{sub 18}, respectively. Because its molecule is larger and excluded frommore » the deepest sites buried in the bonded layer, the adsorption data of caffeine follow bi-Langmuir isotherm model behavior on both adsorbents. In contrast, with acetonitrile/water solutions, the adsorption data of both phenol and caffeine deviate far less from linear behavior. They were best modeled by the sum of a Langmuir and a BET isotherm models. The Langmuir term represents the adsorption of the analyte on the high-energy sites located within the C{sub 18} layers and the BET term its adsorption on the low-energy sites and its accumulation in an adsorbed multilayer system of acetonitrile on the bonded alkyl chains. The formation of a complex adsorbed phase containing up to four layers of acetonitrile (with a thickness of 3.4 {angstrom} each) was confirmed by the excess adsorption isotherm data measured for acetonitrile on Discovery-C{sub 18}. A simple interpretation of this change in the isotherm curvature at high concentrations when methanol is replaced with acetonitrile as the organic modifier is proposed, based on the structure of the interface between the C{sub 18} chains and the bulk mobile phase. This new model accounts for all the experimental observations.« less

Synthesis of silver nanoparticles by chemical reduction at various fraction of MSA and their structure characterization

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

Diantoro, Markus, E-mail: m-diantoror@yahoo.com; Fitrianingsih, Rina, E-mail: m-diantoror@yahoo.com; Mufti, Nandang, E-mail: m-diantoror@yahoo.com

Nanosilver is currently one of the most common engineered nanomaterials and is used in many applications that lead to the release of silver nanoparticles and silver ions into aqueous systems. Nanosilver also possesses enhanced antimicrobial activity and bioavailability that may less environmental risk compared with other manufactured nanomaterials. Described in this research are the synthesis of silver nanoparticle produced by chemical reduction from silver nitrate (AgNO{sub 3}) solution. As a reducing agent, Sodium Borohydride (NaBH{sub 4}) was used and mercaptosuccinic Acid (MSA) as stabilizer to prevent the nanoparticle from aglomerating. It was also used two kinds of solvent, they aremore » water and methanol. In typical experiment MSA was dissolve in methanol with a number of variation of molarity i.e. 0,03 M, 0,06 M, 0,12 M, 0,15 M, and the mixture was kept under vigorous stirring in an ice bath. A solution of silver nitrate of 340 mg in 6,792 ml water was added. A freshly prepared aqueous solution of sodium borohydride (756,6 mL in 100 mL of water) was added drop wisely. The solution was kept for half an hour for stirring and were allowed to settle down in methanol. The obtained samples then characterized by means of x-ray diffractometer, and scanning electron microscopy, as well as transmission electron microscopy to obtain their structures of silver nanoparticles, morphology, and sizes. It is shown that diameter of silver nanoparticle sized about 24.3 nm (Ag@MSA 0.03 M), 20.4 nm (Ag@MSA 0.06 M), 16.8 nm (Ag@MSA 0.12 M), 16.9 nm (Ag@MSA 0.15 M) which was calculated by Scherrer formula by taking the FWHM from fitting to Gaussian. The phases and lattice parameter showed that there is no significant change in its volume by increasing molarity of stabilizer. In contrast, the size of particles is decreasing.« less

Photo-electrochemical Oxidation of Organic C1 Molecules over WO3 Films in Aqueous Electrolyte: Competition Between Water Oxidation and C1 Oxidation.

PubMed

Reichert, Robert; Zambrzycki, Christian; Jusys, Zenonas; Behm, R Jürgen

2015-11-01

To better understand organic-molecule-assisted photo-electrochemical water splitting, photo-electrochemistry and on-line mass spectrometry measurements are used to investigate the photo-electrochemical oxidation of the C1 molecules methanol, formaldehyde, and formic acid over WO3 film anodes in aqueous solution and its competition with O2 evolution from water oxidation O2 (+) and CO2 (+) ion currents show that water oxidation is strongly suppressed by the organic species. Photo-electro-oxidation of formic acid is dominated by formation of CO2 , whereas incomplete oxidation of formaldehyde and methanol prevails, with the selectivity for CO2 formation increasing with increasing potential and light intensity. The mechanistic implications for the photo-electro-oxidation of the organic molecules and its competition with water oxidation, which could be derived from this novel approach, are discussed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Extraction, Characterization, Stability and Biological Activity of Flavonoids Isolated from Chamomile Flowers

PubMed Central

Srivastava, Janmejai K; Gupta, Sanjay

2009-01-01

Dried flowers of Chamomile (Matricaria chamomilla) are largely used for their medicinal properties. In the present study, we examined the pharmacological properties of aqueous and methanolic fraction isolated from two varieties of German chamomile. HPLC-MS analysis of chamomile extract confirmed apigenin-7-O-glucoside as the major constituent of chamomile; some minor glycoside components were observed along with essential oils. These glucosides are highly stable in solution at different temperature range and their degradation occurs after long-term storage and extraction conditions at different pH and solvent. Methanolic fraction isolated from chamomile flowers demonstrated higher biologic response in inhibiting cell growth and causing induction of apoptosis in various human cancer cell lines compared to aqueous chamomile fraction. Apigenin glucosides inhibited cancer cell growth through deconjugation of glycosides that occurs in the cellular compartment to produce aglycone, apigenin. Taken together, the pharmacological profile of chamomile extract was dependent upon extraction process, storage conditions which affected the biological activity. PMID:20098626

Radiation Induced Incorporation of CO in Pure and Aqueous Methanol

NASA Astrophysics Data System (ADS)

Jung, Hak-Jin; Getoff, Nikola; Lorbeer, Eberhard

1994-05-01

Pure and aqueous methanol were used for radiation induced incorporation of CO at elevated pressure (up to 15 bar). The initial yields (Gi) of the main products in pure methanol under 15 bar CO and 1 bar N2O were found to be: Gi(formaldehyde) = 3.80 and Gi(glycolic aldehyde) = 2.0. For aqueous (10-2 mol · dm-3) methanol under 15 bar CO (dose: 0.557 kGy, pH = 2): the yields were G(formaldehyde) = 5.44, G(glycolic aldehyde) = 4.0 and G(oxalic acid) = 7.7. At pH = 7 the yields were essentially lower, namely: G(formaldehyde) = 3.2, G(glycolic aldehyde) = 2.0, G(formate) = 3.8 and G(oxalate) = 5.0. Probable reaction-mechanisms for the product formation are discussed.

Evaluation of a new eastern blotting technique for the analysis of ginsenoside Re in American ginseng berry pulp extracts.

PubMed

Morinaga, Osamu; Uto, Takuhiro; Yuan, Chun-Su; Tanaka, Hiroyuki; Shoyama, Yukihiro

2010-06-01

A new eastern blotting technique has been established for ginsenoside Re (G-Re) contained in American ginseng berry pulp extracts. G-Re in American ginseng berry pulp was extracted using 100% methanol, 100% ethanol, 50% aqueous methanol, and 50% aqueous ethanol. The combined crude extracts were applied onto a polyethersulfone membrane and developed using the methanol-water-acetic acid solvent system (45:55:1 v/v). Separated components were immunostained using anti-G-Re monoclonal antibody. G-Re was first specifically detected and then quantitatively analyzed using NIH Imaging software. We also confirmed that the most suitable solvent was 50% aqueous methanol for extracting G-Re from American ginseng berry pulp. (c) 2009 Elsevier B.V. All rights reserved.

Single- and double-strand break formation in DNA irradiated in aqueous solution: dependence on dose and OH radical scavenger concentration

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

Siddiqi, M.A.; Bothe, E.

The yields of single- and double-strand breaks (SSB and DSB) in calf thymus DNA, after /sup 60/Co gamma irradiation in dilute aqueous solution, have been determined via molecular weight measurements using a low-angle laser light scattering technique. The irradiations were administered to N/sub 2/O-containing solutions of DNA in the absence and presence of oxygen and with different concentrations of the OH radical scavengers phenol, tertiary butanol, and methanol. OH radicals were found to produce SSB linearly with dose with a G value of 55 nmol J-1 and 54 nmol J-1 in deoxygenated and oxygenated solutions, respectively. DSB were formed accordingmore » to a linear-quadratic dose relationship and the G value of linearly formed DSB were GDSB alpha(r.t.) = 3.5 nmol J-1 in deoxygenated and 3.2 nmol J-1 in oxygenated solution. The ratio of GSSB/GDSB alpha(r.t.) = gamma of 19 +/- 6 was independent of the scavenger concentration in the case of tertiary butanol and methanol-containing solutions. GDSB alpha(r.t.) is interpreted to result from a radical site transferred from a sugar moiety of the cleaved strand to the complementary intact strand. This process of radical transfer and subsequent cleavage of the second strand occurs with a probability of about 6 +/- 2% in the presence of oxygen at all scavenger concentrations studied. These data on scavenging capacity on GDSB alpha(r.t.) suggest that the double-strand breakage produced via radical transfer remains higher than that resulting from direct effect, up to scavenging capacities of about 10(9) s-1.« less

Anticandidal, antibacterial, cytotoxic and antioxidant activities of Calendula arvensis flowers.

PubMed

Abudunia, A-M; Marmouzi, I; Faouzi, M E A; Ramli, Y; Taoufik, J; El Madani, N; Essassi, E M; Salama, A; Khedid, K; Ansar, M; Ibrahimi, A

2017-03-01

Calendula arvensis (CA) is one of the important plants used in traditional medicine in Morocco, due to its interesting chemical composition. The present study aimed to determine the anticandidal, antioxidant and antibacterial activities, and the effects of extracts of CA flowers on the growth of myeloid cancer cells. Also, to characterize the chemical composition of the plant. Flowers of CA were collected based on ethnopharmacological information from the villages around the region Rabat-Khemisset, Moroccco. The hexane and methanol extracts were obtained by soxhlet extraction, while aqueous extracts was obtained by maceration in cold water. CA extracts were assessed for antioxidant activity using four different methods (DPPH, FRAP, TEAC, β-carotene bleaching test). Furthermore, the phenolic and flavonoid contents were measured, also the antimicrobial activity has been evaluated by the well diffusion method using several bacterial and fungal strains. Finally, extracts cytotoxicity was assessed using MTT test. Phytochemical quantification of the methanolic and aqueous extracts revealed that they were rich with flavonoid and phenolic content and were found to possess considerable antioxidant activities. MIC values of methanolic extracts were 12.5-25μg/mL. While MIC values of hexanolic extracts were between 6.25-12.5μg/mL and were bacteriostatic for all bacteria while methanolic and aqueous extracts were bactericidal. In addition, the extracts exhibited no activity on Candida species except the methanolic extract, which showed antifungal activity onCandida tropicalis 1 and Candida famata 1. The methanolic and aqueous extracts also exhibited antimyeloid cancer activity (IC 50 of 31μg/mL). In our study, we conclude that the methanolic and aqueous extracts were a promising source of antioxidant, antimicrobial and cytotoxic agents. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Potent antibacterial, antioxidant and toxic activities of extracts from Passiflora suberosa L. leaves

PubMed Central

Bandara, Kumudu R.V.; Padumadasa, Chayanika

2018-01-01

Passiflora suberosa L. belonging to the family Passifloraceae is an important medicinal plant used in traditional medicinal system in Sri Lanka to treat diabetes, hypertension and skin diseases. We extracted P. suberosa leaves under reflux conditions using different solvents (hexane, chloroform, methanol and water), then subjected to phytochemical screening. Alkaloids, flavonoids and saponins and saponins and anthraquinones were present in hexane and chloroform extracts. Alkaloids, unsaturated sterols, triterpenes, saponins, flavonoids and tannins were observed in both methanol and aqueous extracts. Proanthocyanidins were observed only in the aqueous extract. Hence, aqueous and methanol extracts with most classes of phytochemicals present were subjected to antimicrobial, antioxidant, antihaemolytic activities and Brine shrimp lethality studies. Antibacterial activity and minimum inhibition concentrations were evaluated using three Gram-positive (Bacillus subtilis, Staphylococcus aureus and Enterococcus faecium) and three Gram-negative bacteria (Pseudumonas aeruginosa, Salmonella typhimuriam and Escherichia coli). The results indicated that only the methanol extract of P. suberosa exhibited antibacterial activities against all the strains of Gram-negative and Gram-positive bacterial with stronger activity against Gram-negative bacteria. DPHH (2,2-diphenyl-1-picrylhydrazy) scavenging assay was adopted to evaluate antioxidant properties while antihaemolytic and toxic activities were studied respectively using cow blood and Brine shrimp lethality assay. The IC50 values of the aqueous extract in both antioxidant and antihaemolytic assays were significantly lower than the standard ascorbic acid. Similar results were observed in the Brine shrimp lethality assay. In conclusion both aqueous and methanol extracts of P. suberosa leaves showed the presence of majority of phytochemicals including proanthocyanidins. Antibacterial activity was obtained only for methanol extract with better activity against Gram-negative bacteria. The aqueous extract showed better antioxidant, antihaemolytic and toxic activities than the methanol extract and their respective standards. Further investigations on the chemical composition and possible isolation of active ingredients is warranted. PMID:29868259

Amplification of hofmeister effect by alcohols.

PubMed

Xu, Yun; Liu, Guangming

2014-07-03

We have demonstrated that Hofmeister effect can be amplified by adding alcohols to aqueous solutions. The lower critical solution temperature behavior of poly(N-isopropylacrylamide) has been employed as the model system to study the amplification of Hofmeister effect. The alcohols can more effectively amplify the Hofmeister effect following the series methanol < ethanol < 1-propanol < 2-propanol for the monohydric alcohols and following the series d-sorbitol ≈ xylitol ≈ meso-erythritol < glycerol < ethylene glycol < methanol for the polyhydric alcohols. Our study reveals that the relative extent of amplification of Hofmeister effect is determined by the stability of the water/alcohol complex, which is strongly dependent on the chemical structure of alcohols. The more stable solvent complex formed via stronger hydrogen bonds can more effectively differentiate the anions through the anion-solvent complex interactions, resulting in a stronger amplification of Hofmeister effect. This study provides an alternative method to tune the relative strength of Hofmeister effect besides salt concentration.

Optimisation of the microplate resazurin assay for screening and bioassay-guided fractionation of phytochemical extracts against Mycobacterium tuberculosis.

PubMed

O'Neill, Taryn E; Li, Haoxin; Colquhoun, Caitlyn D; Johnson, John A; Webster, Duncan; Gray, Christopher A

2014-01-01

Because of increased resistance to current drugs, there is an urgent need to discover new anti-mycobacterial compounds for the development of novel anti-tuberculosis drugs. The microplate resazurin assay (MRA) is commonly used to evaluate natural products and synthetic compounds for anti-mycobacterial activity. However, the assay can be problematic and unreliable when screening methanolic phytochemical extracts. To optimise the MRA for the screening and bioassay-guided fractionation of phytochemical extracts using Mycobacterium tuberculosis H37Ra. The effects of varying assay duration, resazurin solution composition, solvent (dimethyl sulphoxide - DMSO) concentration and type of microtitre plate used on the results and reliability of the MRA were investigated. The optimal bioassay protocol was applied to methanolic extracts of medicinal plants that have been reported to possess anti-mycobacterial activity. The variables investigated were found to have significant effects on the results obtained with the MRA. A standardised procedure that can reliably quantify anti-mycobacterial activity of phytochemical extracts in as little as 48 h was identified. The optimised MRA uses 2% aqueous DMSO, with an indicator solution of 62.5 µg/mL resazurin in 5% aqueous Tween 80 over 96 h incubation. The study has identified an optimal procedure for the MRA when used with M. tuberculosis H37Ra that gives rapid, reliable and consistent results. The assay procedure has been used successfully for the screening and bioassay-guided fractionation of anti-mycobacterial compounds from methanol extracts of Canadian medicinal plants. Copyright © 2014 John Wiley & Sons, Ltd.

Theoretical study on substituent and solvent effects for nanocubes formed with gear-shaped amphiphile molecules.

PubMed

Mashiko, T; Hiraoka, S; Nagashima, U; Tachikawa, M

2017-01-04

Gear-shaped amphiphile molecules (1) recently synthesized by Hiraoka et al. self-assemble into a hexameric structure, nanocubes (1 6 ), in 25% aqueous methanol due to a solvophobic effect. Here we have carried out molecular dynamic simulations to elucidate the stability of these hexameric capsules (1 6 and 2 6 ) in water, 25% aqueous methanol, and methanol. In all solvents, the 1 6 nanocubes are maintained for all trajectories. On the other hand, 2 6 was found to collapse for one trajectory in water and seven trajectories in 25% aqueous methanol. In a pure methanol solvent, 2 6 was found to collapse for all trajectories. The number of collapsed trajectories of 2 6 increased with the amount of methanol in the solvent. We therefore focused on the structure of the π-π stacking between pyridyl groups and the CH-π interactions between the methyl and pyridyl groups within the nanocube. Our study clearly shows the role played by the methanol solvent molecules in the assembly of the nanocube in terms of the substituent and solvent effects at the molecular level, and that these substituent and solvent effects are important for the self-assembly of the nanocubes.

Phytochemical analysis, antimicrobial, antioxidant and urease inhibitory potential of Cyphostemma digitatum Lam.

PubMed

Khan, Rasool; Saif, Abdullah Qasem; Quradha, Mohammad Mansour; Ali, Jawad; Rauf, Abdur

2015-01-01

In this paper we report the antimicrobial, antiradical and urease inhibitory potential along with photochemical investigation of the crude extracts of Cyphostemma digitatum Lam. Phytochemical screening of both the crude (hot/cold) alcoholic and aqueous extracts of C. digitatum showed the presence of alkaloids, flavonoids, saponins, coumarins, steroids, terpenoids and tannins. The crude methanolic extract (hot/cold) exhibited good antioxidant activity, while the aqueous extract was a weak antioxidant. The crude methanolic extract was found to be more active against Bacillus subtilis, while both the extracts showed moderate antifungal potential, the methanolic crude extract showed good urease inhibitory activity compared with the aqueous crude extract.

The kinetics and mechanism of the ferrate(VI) oxidation of hydroxylamines.

PubMed

Johnson, Michael D; Hornstein, Brooks J

2003-10-20

Aqueous solutions of potassium ferrate(VI) cleanly and rapidly oxidize hydroxylamine to nitrous oxide, N-methylhydroxylamine to nitrosomethane, N-phenylhydroxylamine to nitrosobenzene, and O-methylhydroxylamine to methanol and nitrogen. The kinetics show first-order behavior with respect to each reactant and a two term component representing acid dependent and independent pathways. A general mechanism involving intermediate formation coupled with a two-electron oxidation is proposed.

PREPARATION OF DIBASIC ALUMINUM NITRATE

DOEpatents

Gresky, A.T.; Nurmi, E.O.; Foster, D.L.; Wischow, R.P.; Savolainen, J.E.

1960-04-01

A method is given for the preparation and recovery of basic aluminum nltrates having an OH: Al ratio of at least two, comprising two steps. First, metallic aluminum is dissolved in aqueous Al(NO/sub 3/)/sub 3/, in the presence of a small quantity of elemental or ionic mercury, to increase its Al: NO/sub 3/ ratio into the range 1 to 1.2. The resulting aqueous solution is then added to an excess of a special organic solvent, typically a mixture of five parts methanol and six parts diethyl ether, whereupon the basic aluminum nitrate, e.g. Al/sub 6/(OH)/sub 13/-(NO/sub 3/)/sub 5/, recoverably precipitates.

Comment on "Relating side chain organization of PNIPAm with its conformation in aqueous methanol" by D. Mukherji, M. Wagner, M. D. Watson, S. Winzen, T. E. de Oliveira, C. M. Marques and K. Kremer, Soft Matter, 2016, 12, 7995.

PubMed

Pica, Andrea; Graziano, Giuseppe

2017-11-01

In a recent article, Kremer and co-workers have combined NMR measurements and very long, all-atom MD simulations to strengthen their original claim that PNIPAM cononsolvency in water-methanol solutions is driven by the ability of MeOH molecules to bridge different monomers far away along the polymeric chain. In this comment, the results presented by Kremer and co-workers are reviewed, analyzed, and questioned regarding their ability to provide support to the bridging mechanism. Here, some pieces of evidence are provided to show that: (1) the solvent-excluded volume effect plays always a fundamental role in polymer collapse; (2) PNIPAM cononsolvency is caused by the geometric-energetic frustration experienced by the polymer when it can interact with both water and methanol molecules at the same time.

Techniques for sensing methanol concentration in aqueous environments

NASA Technical Reports Server (NTRS)

Narayanan, Sekharipuram R. (Inventor); Chun, William (Inventor); Valdez, Thomas I. (Inventor)

2001-01-01

An analyte concentration sensor that is capable of fast and reliable sensing of analyte concentration in aqueous environments with high concentrations of the analyte. Preferably, the present invention is a methanol concentration sensor device coupled to a fuel metering control system for use in a liquid direct-feed fuel cell.

Anti-proliferative and mutagenic activities of aqueous and methanol extracts of leaves from Pereskia bleo (Kunth) DC (Cactaceae).

PubMed

Er, Hui Meng; Cheng, En-Hsiang; Radhakrishnan, Ammu Kutty

2007-09-25

The anti-proliferative effects of the aqueous and methanol extracts of leaves of Pereskia bleo (Kunth) DC (Cactaceae) against a mouse mammary cancer cell line (4T1) and a normal mouse fibroblast cell line (NIH/3T3) were evaluated under an optimal (in culture medium containing 10% foetal bovine serum (FBS)) and a sub-optimal (in culture medium containing 0.5% FBS) conditions. Under the optimal condition, the aqueous extract showed a significant (p<0.05) anti-proliferative effect at 200 microg/mL and 300 microg/mL in 4T1 cells and 300 microg/mL in NIH/3T3 cells, whereas the methanol extract did not show any notable anti-proliferative effect in these cell lines, at any of the concentrations tested. Under the sub-optimal condition, the aqueous extract showed a significant (p<0.05) anti-proliferative effect at 200 microg/mL and 300 microg/mL in NIH/3T3 cells, whilst the methanol extract showed a significant (p<0.05) anti-proliferative effect at 200 microg/mL and 300 microg/mL in both cell lines. An upward trend of apoptosis was observed in both 4T1 and NIH/3T3 cells treated with increasing concentrations of the aqueous extract. The level of apoptosis observed at all the concentrations of the aqueous extract tested was consistently higher than necrosis. There was a significant (p<0.05) increase in the level of necrosis observed in the 4T1 cells treated with 300 microg/mL of the methanol extract. Generally, the level of necrosis was noted to be higher than that of apoptosis in the methanol extract-treated cells. The mutagenicity assay performed showed that in the absence of S-9 liver metabolic activation, the extract was not mutagenic up to the concentration of 165 microg/mL . However, in the presence of S-9 liver metabolic activation, the aqueous extract was mutagenic at all the concentrations tested. This study shows that both the aqueous and methanol extracts of the leaves from Pereskia bleo (Kunth) DC (Cactaceae) do not have appreciable anti-proliferative effect on the 4T1 and NIH/3T3 cells as the EC(50) values obtained are greater than 50 microg/mL when tested under optimal culture condition. Moreover, the aqueous extract may form mutagenic compound(s) upon the metabolisation by liver enzymes.

The water-hydrophobic interface: neutral and charged solute adsorption at fluorocarbon and hydrocarbon self-assembled monolayers (SAMs).

PubMed

Hopkins, Adam J; Richmond, Geraldine L

2013-03-01

Adsorption of small molecular solutes in an aqueous solution to a soft hydrophobic surface is a topic relevant to many fields. In biological and industrial systems, the interfacial environment is often complex, containing an array of salts and organic compounds in the solution phase. Additionally, the surface itself can have a complex structure that can interact in unpredictable ways with small solutes in its vicinity. In this work, we studied model adsorption processes on hydrocarbon and fluorocarbon self-assembled monolayers by using vibrational sum frequency spectroscopy, with methanol and butylammonium chloride as adsorbates. The results indicate that differences in surface functionality have a significant impact on the organization of adsorbed organic species at hydrophobic surfaces.

Antimicrobial properties of the stem bark of Saraca indica (Caesalpiniaceae).

PubMed

Sainath, R Shilpakala; Prathiba, J; Malathi, R

2009-01-01

Chloroform, methanol, aqueous and ethanolic extracts of the stem bark of Saraca indica were investigated for their antibacterial and antifungal activity against standard strains of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Bacillus cereus, Klebsiella pneumoniae, Proteus mirabilis, Salmonella typhimurium and Streptococcus pneumoniae and the fungi: Candida albicans and Cryptococcus albidus. Methanolic and aqueous extract exhibited antimicrobial activity with MIC ranging from 0.5-2% and 1-3% respectively. Methanolic extract exhibited the strongest activity against both bacteria and fungi.

Microbial screening test for lignite degradation. Quarterly progress report No. 2, April-June 1985

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

Yen, T.F.

1985-01-01

Fractionation of lignite was performed by means of: (1) benzene-methanol followed by aqueous alkaline extraction; and (2) benzene followed by methanol-alkaline extraction. The residue obtained by the latter fractionation was oxidized by means of cupric oxide and separated into methanol soluble fraction and methanol insoluble residue. Methanol-alkaline fraction was further divided into methylene chloride extractable portion and methylene chloride non-extractable portion. Fourier Transform Infrared Spectroscopy (FT-IR) was employed to characterize functional groups present in the raw lignite sample, benzene-methanol fraction, aqueous alkaline fraction, lignite residue, and benzene fraction. FT-IR was also used for the analysis of both methylene chloride extractablemore » and non-extracted portions. The following are some functional groups identified by the spectra of the fractions mentioned above: OH, amide, aromatic, CH, CO, C=C, CH/sub 2/, C-CH/sub 3/, SiCH/sub 3/, epoxide, and C-O-C. Both, raw lignite sample and aqueous alkaline fraction produced positive results for P. versicolor growth, whereas benzene-methanol fraction and lignite residue produced negative results. Acclimation of P. versicolor to lignite was accomplished up to 80% lignite and 20% neopeptone and maltose. 10 refs., 9 figs., 6 tabs.« less

Adsorptive separation in bioprocess engineering

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

Huang, E.W.Y.

1987-01-01

The invention and development of an energy-efficient separation technique for recovery of desired chemicals from biomass conversion would greatly enhance the economic viability of this bioprocess. Adsorptive separation of several chemicals from aqueous solution was studied in this thesis. The desired species were recovered from the dilute aqueous solution by using crosslinked polyvinylpyridine resin to effect selective sorption. The sorbed chemicals were then removed from the resin by either thermal regeneration or elution with some appropriate desorbents. The effects of temperature, pH value, and solute concentration on resin swelling were investigated. The adsorption equilibrium isotherms, resin capacities and resin selectivitiesmore » of methanol, ethanol, 1-propanol, isopropanol, glycerol, acetone, 1-butanol, tert-butanol, and 2,3-butanediol were determined to study the homologies. Furthermore, acetic acid, butyric acid, hydrochloric acid, lactic acid, and sulfuric acid were recovered from very dilute aqueous solutions. The concentration of the sorbed chemical in the stationary phase can be many times higher than in the mobile phase for some acids. Finally, different types of equilibrium isotherms were used to fit the experimental data. A mathematical model was developed by using the theory of interference to predict the breakthrough curves and the process efficiency to provide information for large-scale process design and development.« less

Evaluation of wound healing activity of root of Mimosa pudica.

PubMed

Kokane, Dnyaneshwar D; More, Rahul Y; Kale, Mandar B; Nehete, Minakshi N; Mehendale, Prachi C; Gadgoli, Chhaya H

2009-07-15

Mimosa pudica, commonly known as touch-me-not, is used in folklore medicine in arresting bleeding and in skin diseases. There was no scientific evidence justifying the use of Mimosa pudica, therefore the present study was aimed at evaluation of wound healing activity of the plant. In the present study the roots of Mimosa pudica were studied for wound healing activity by incorporating the methanolic and the total aqueous extract in simple ointment base B.P. in concentration of 0.5% (w/w), 1% (w/w) and 2% (w/w). Wound healing activity was studied in three types of model in rats viz. excision, incision and estimation of biochemical parameter. In case of the excision wound model wound contraction and period of epithelization was studied while in incision wound model was evaluated by determining tensile strength and hydroxyproline content in the scab. Treatment of wound with ointment containing 2% (w/w) the methanolic and 2% (w/w) the total aqueous extract exhibited significant (P<0.001) wound healing activity. The methanolic and total aqueous extracts were analyzed for total phenols content equivalent to Gallic acid. The content of total phenols was 11% (w/w) and 17% (w/w) in methanolic and total aqueous extract respectively. The methanolic extract exhibited good wound healing activity probably due to phenols constituents.

Antiparkinsonian effects of aqueous methanolic extract of Hyoscyamus niger seeds result from its monoamine oxidase inhibitory and hydroxyl radical scavenging potency.

PubMed

Sengupta, T; Vinayagam, J; Nagashayana, N; Gowda, B; Jaisankar, P; Mohanakumar, K P

2011-01-01

Hyoscyamus species is one of the four plants used in Ayurveda for the treatment of Parkinson's disease (PD). Since Hyoscyamus niger was found to contain negligible levels of L-DOPA, we evaluated neuroprotective potential, if any, of characterized petroleum ether and aqueous methanol extracts of its seeds in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of PD in mice. Air dried authenticated H. niger seeds were sequentially extracted using petroleum ether and aqueous methanol and were characterized employing HPLC-electrochemistry and LCMS. Parkinsonian mice were treated daily twice with the extracts (125-500 mg/kg, p.o.) for two days and motor functions and striatal dopamine levels were assayed. Administration of the aqueous methanol extract (containing 0.03% w/w of L-DOPA), but not petroleum ether extract, significantly attenuated motor disabilities (akinesia, catalepsy and reduced swim score) and striatal dopamine loss in MPTP treated mice. Since the extract caused significant inhibition of monoamine oxidase activity and attenuated 1-methyl-4-phenyl pyridinium (MPP+)-induced hydroxyl radical (·OH) generation in isolated mitochondria, it is possible that the methanolic extract of Hyoscyamus niger seeds protects against parkinsonism in mice by means of its ability to inhibit increased ·OH generated in the mitochondria.

Separation and preconcentration of Ag(I) in aqueous samples by flotation as an ion-associate using iodide and ferroin followed the determination by flame atomic absorption spectrometry.

PubMed

Hosseini, Mohammad Saeid; Hashemi-Moghaddam, Hamid; Kardan-Moghaddam, Gholamreza

2007-01-01

A simple method for separation/preconcentration and determination of Ag(I) in aqueous samples is described. The method is based on formation of an ion-associate between Ag(I)-iodide complex and ferroin, which can be floated at the interface of the aqueous/n-heptane phases. The flotation process was carried out using 500-ml aliquot of the aqueous solution and the floated layer was dissolved in 5 ml of 1 M HNO3 containing methanol (50% v/v) as the solvent. The Ag(I) content was then determined by flame atomic absorption spectrometry (FAAS). The method so could be considered as an enrichment process, was achieved to a quantitative feature, when the pH of the solution was adjusted to 4 and the concentrations of iodide and ferroin were about 3.2 x 10(-4) M and 6.25 x 10(-5) M, respectively. The LOD and RSD (n = 7) were obtained 1.0 x 10(-8) M and 2.4%, respectively. It was found that a large number of cations and anions even at high considerably foreign ion/Ag(I) ratios were not interfered. The method was applied satisfactorily to recovery of Ag(I) from different aqueous samples.

Ultraviolet light assisted extraction of flavonoids and allantoin from aqueous and alcoholic extracts of Symphytum officinale

PubMed Central

Al-Nimer, Marwan S. M.; Wahbee, Zainab

2017-01-01

Aim: Symphytum officinale (comfrey) is a medicinal plant commonly used in decoction and to treat ailments. It protects the skin against ultraviolet (UV)-irradiation. UV irradiation may induce variable effects on the constituents of herbal extracts and thereby may limit or improve the advantages of using these extracts as medicinal supplements. This study aimed to assess the effect of UV radiations including UV-A, UV-B, and UV-C on the constituents of S. officinale aqueous and alcoholic extracts. Materials and Methods: Comfrey extracts (1% w/v) were prepared using distilled water, ethanol, and methanol. They were exposed to wavelengths of UV-A, UV-B, and UV-C for 10 min. The principal peak on the UV-spectroscopy scanning, the flavonoids, reducing power, and the allantoin levels were determined before and after irradiation. Results: UV irradiation reduces the magnitude of the principle peak at 355 nm wavelength of the aqueous infusion and methanol extracts. It improves the levels of flavonoids and reducing power of the aqueous extracts and increases the levels of allanotoin in aqueous and methanol extracts. Conclusions: UV-radiation enhances the yields of active ingredient of comfrey extracted with methanol, whereas improves the flavonoids, reducing power, and allantoin levels of comfrey extracted by the aqueous infusion method. UV-radiation reduces the levels of flavonoids, reducing power and allantoin when the comfrey extracted by alcohols. PMID:28894626

An inorganic/organic hybrid magnetic network as a colorimetric fluorescent nanosensor and its recognizing behavior toward Hg2+

NASA Astrophysics Data System (ADS)

Zeng, Xianfei; Xu, Yaohui; Chen, Xiumin; Ma, Wenhui; Zhou, Yang

2017-11-01

An inorganic/organic hybrid magnetic Fe3O4@SiO2 network functionalized with rhodamine derivatives was devised as a nanosensor for selective detection and removal of Hg2+ in this work. The inorganic/organic hybrid composites showed naked-eye color change in water/methanol media. The distinct color change on the surface of functionalized composite network was observed by separating and drying from aqueous solution after adsorbing Hg2+. The fluorescence spectra indicated that the functionalized nanosensor was highly sensitive and selective to Hg2+ in aqueous solution. Density functional theory (DFT) calculation was performed, which revealed a mechanism of fluorescence generated from Hg2+ induced desulfurization of rhodamine derivatives via forming new five-membered ring structure. The as-obtained composites not only had an excellent adsorption capability for Hg2+, but also showed a strong magnetic sensitivity, which allowed one to separate the functionalized magnetic nanocomposites from the solution.

In vivo antimalarial activity of crude extracts and solvent fractions of leaves of Strychnos mitis in Plasmodium berghei infected mice.

PubMed

Fentahun, Selamawit; Makonnen, Eyasu; Awas, Tesfaye; Giday, Mirutse

2017-01-05

Malaria is a major public health problem in the world which is responsible for death of millions particularly in sub-Saharan Africa. Today, the control of malaria has become gradually more complex due to the spread of drug-resistant parasites. Medicinal plants are the unquestionable source of effective antimalarials. The present study aimed to evaluate antiplasmodial activity and acute toxicity of the plant Strychnos mitis in Plasmodium berghei infected mice. Standard procedures were employed to investigate acute toxicity and 4-day suppressive effect of crude aqueous and hydro-methanolic extracts of the leaves of Strychnos mitis against P. berghei in Swiss albino mice. Water, n-hexane and chloroform fractions, obtained from crude hydro-methanolic extract, were also tested for their suppressive effect against P. berghei. All crude extracts revealed no obvious acute toxicity in mice up to the highest dose administered (2000 mg/kg). All crude and solvent fractions of the leaves of Strychnos mitis inhibited parasitaemia significantly (p < 0.01). At the highest dose of 600 mg/kg, both aqueous and hydro-methanolic extracts demonstrated higher performance with 95.5 and 93.97% parasitaemia suppression, respectively. All doses of crude extracts and fractions of leaves of Strychnos mitis prolonged survival time of infected mice dose dependently. The highest two doses of the crude aqueous and hydro-methanolic extracts, and chloroform and aqueous fractions prevented weight loss in a dose dependent manner. Whereas, all doses of n-hexane fraction prevented loss of body weight but not in a dose dependent manner. The crude aqueous extract at the doses of 400 mg/kg and 600 mg/kg and hydro-methanolic extract at all dose levels significantly (p < 0.01) prevented packed cell volume reduction. Crude aqueous extract at a dose of 600 mg/kg and hydro-methanolic extract at all dose levels significantly prevented temperature reduction. Phytochemical screening of the crude aqueous and hydro-methanolic extracts revealed the presence of alkaloids, anthraquinones, glycosides, terpenoids, saponins, tannins and phenols. The results of this study provide support the traditional therapeutic use of Strychnos mitis for treatment of malaria. However, further in-depth study is needed to evaluate the potential of the plant towards the development of new antimalarial agent.

Characterization of supramolecular (H2O)18 water morphology and water-methanol (H2O)15(CH3OH)3 clusters in a novel phosphorus functionalized trimeric amino acid host.

PubMed

Raghuraman, Kannan; Katti, Kavita K; Barbour, Leonard J; Pillarsetty, Nagavarakishore; Barnes, Charles L; Katti, Kattesh V

2003-06-11

Phosphorus functionalized trimeric alanine compounds (l)- and (d)-P(CH(2)NHCH(CH(3))COOH)(3) 2 are prepared in 90% yields by the Mannich reaction of Tris(hydroxymethyl)phosphine 1 with (l)- or (d)- Alanine in aqueous media. The hydration properties of (l)-2 and (d)-2 in water and water-methanol mixtures are described. The crystal structure analysis of (l)-2.4H(2)O, reveals that the alanine molecules pack to form two-dimensional bilayers running parallel to (001). The layered structural motif depicts two closely packed monolayers of 2 each oriented with its phosphorus atoms projected at the center of the bilayer and adjacent monolayers are held together by hydrogen bonds between amine and carboxylate groups. The water bilayers are juxtaposed with the H-bonded alanine trimers leading to 18-membered (H(2)O)(18) water rings. Exposure of aqueous solution of (l)-2 and (d)-2 to methanol vapors resulted in closely packed (l)-2 and (d)-2 solvated with mixed water-methanol (H(2)O)(15)(CH(3)OH)(3) clusters. The O-O distances in the mixed methanol-water clusters of (l)-2.3H(2)O.CH(3)OH and (d)-2.3H(2)O.CH(3)OH (O-O(average) = 2.857 A) are nearly identical to the O-O distance observed in the supramolecular (H(2)O)(18) water structure (O-O(average) = 2.859 A) implying the retention of the hydrogen bonded structure in water despite the accommodation of hydrophobic methanol groups within the supramolecular (H(2)O)(15)(CH(3)OH)(3) framework. The O-O distances in (l)-2.3H(2)O.CH(3)OH and (d)-2.3H(2)O.CH(3)OH and in (H(2)O)(18) are very close to the O-O distance reported for liquid water (2.85 A).

Effect of butanolic fraction of yellow and black maca (Lepidium meyenii) on the sperm count of adult mice.

PubMed

Inoue, N; Farfan, C; Gonzales, G F

2016-10-01

Lepidium meyenii, known as maca, is a popular nutraceutical food which is grown over 4,000 m above sea level in the Peruvian central highlands. Maca contains alkaloids, but there are no studies on their biological effects. The butanol fraction obtained from methanol extract of maca hypocotyls contains alkaloids. The effects of butanol/aqueous fractions partitioned from methanol extract of yellow and black maca were examined. Total phenolic content (TPC) and antioxidant capacity by 2,2'-diphenyl-1-picrylhydrazyl were used to evaluate maca fractions in vitro. Daily sperm production and sperm count in epididymis and vas deferens in mice were determined as biological effect of maca extracts in vivo. Yellow maca (21.7%±0.69) had better antioxidant capacity than black maca (18.2% ± 0.12; p < .01). Antioxidant activity was better in the methanolic fraction than in the aqueous fraction of yellow or black maca. TPC is higher in the aqueous fraction than in the methanolic extract of yellow or black maca. Black maca administration resulted in higher concentration of sperm count in epididymis and vas deferens compared to yellow maca. A higher biological effect was observed in methanolic extract and in aqueous extract than in the butanol fraction of maca. In conclusion, better biological effect was observed in the methanolic extract of maca than in its partitioned fractions. © 2016 Blackwell Verlag GmbH.

Spectrophotometric determination of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride by flow injection analysis.

PubMed

Seno, Kunihiko; Matumura, Kazuki; Oshima, Mitsuko; Motomizu, Shoji

2008-04-01

1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC.HCl) is a very useful agent to form amide bonds (peptide bonds) in an aqueous medium. A simple and fast detection system was developed using the reaction with pyridine and ethylenediamine in acidic aqueous solution and spectrophotometric flow injection analysis. The absorbances were measured at 400 nm and the reaction was accelerated at 40 degrees C. The calibration graph showed good linearity from 0 to 10% of EDC.HCl solutions: the regression equation was y=3.15x10(4)x (y, peak area; x, % concentration of EDC.HCl). The RSD was under 1.0%. Sample throughput was 15 h(-1). This method was applied to monitoring the EDC.HCl concentration that remained after the anhydration of phthalic acid in water, esterification of acetic acid in methanol or dehydration condensation of malonic acid and ethylenediamine in water.

Modelling of ceramide interactions with porous graphite carbon in non-aqueous liquid chromatography.

PubMed

West, C; Cilpa, G; Gaudin, K; Chaminade, P; Lesellier, E

2005-09-16

Interactions of solutes on porous graphitic carbon (PGC) with non-aqueous mobile phases are studied by the linear solvation energy relationship (LSER). Studies have been carried out with eight binary mixtures composed of a weak solvent (acetonitrile or methanol) and a strong solvent (tetrahydrofuran, n-butanol, CH2Cl2, 1,1,2-trichloro-2,2,1-trifluoroethane). The systematic analysis of a set of test compounds was performed for each solvent mixture in isocratic mode (50:50). The results were compared to those obtained on PGC with hydro-organic liquids and supercritical fluids. They were then correlated with the observed retention behaviour of lipid compounds, more particularly ceramides.

Hydrolysis of Methylal Catalyzed by Ion Exchange Resins in Aqueous Media

NASA Astrophysics Data System (ADS)

He, Gaoyin; Dai, Fangfang; Shi, Midong; Li, Qingsong; Yu, Yingmin

2018-05-01

In the present work, the chemical equilibrium and kinetics of methylal (PODE1) hydrolysis catalyzed by ion-exchange resin in aqueous solutions were investigated. The study covers temperatures between 333.15 and 363.15 K at various starting compositions covering (PODE1 + MeOH)/water molar ratio ranges from 0.5 to 1.5 in a time scale. On the basis of the experimental results, a mole fraction-based model of the chemical equilibrium and a pseudohomogeneous model are proposed to fit data based on true amount of monomeric formaldehyde. It has been demonstrated that the hydrolysis of PODE1 is slightly endothermic with the enthalpy 8.19 kJ/mol and the rate determining step. Finally, a feed-forward artificial neural networks (ANN) model is developed to model the concentration change of methanol in aqueous solutions. The results showed that the predicted data from designed ANN model were in good agreement with the experimental data with the coefficient ( R 2) of 0.98. Designed ANN provides a reliable method for modeling the hydrolysis reaction of methylal (PODE1).

Effect of stirring on the safety of flammable liquid mixtures.

PubMed

Liaw, Horng-Jang; Gerbaud, Vincent; Chen, Chan-Cheng; Shu, Chi-Min

2010-05-15

Flash point is the most important variable employed to characterize fire and explosion hazard of liquids. The models developed for predicting the flash point of partially miscible mixtures in the literature to date are all based on the assumption of liquid-liquid equilibrium. In real-world environments, however, the liquid-liquid equilibrium assumption does not always hold, such as the collection or accumulation of waste solvents without stirring, where complete stirring for a period of time is usually used to ensure the liquid phases being in equilibrium. This study investigated the effect of stirring on the flash-point behavior of binary partially miscible mixtures. Two series of partially miscible binary mixtures were employed to elucidate the effect of stirring. The first series was aqueous-organic mixtures, including water+1-butanol, water+2-butanol, water+isobutanol, water+1-pentanol, and water+octane; the second series was the mixtures of two flammable solvents, which included methanol+decane, methanol+2,2,4-trimethylpentane, and methanol+octane. Results reveal that for binary aqueous-organic solutions the flash-point values of unstirred mixtures were located between those of the completely stirred mixtures and those of the flammable component. Therefore, risk assessment could be done based on the flammable component flash-point value. However, for the assurance of safety, it is suggested to completely stir those mixtures before handling to reduce the risk. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Comparison of UV Protection Properties of Cotton Fabrics Treated with Aqueous and Methanolic Extracts of Achyranthes aspera and Alhagi maurorum Plants.

PubMed

Nazir, Ahsan; Saleem, Muhammad Asad; Nazir, Faiza; Hussain, Tanveer; Faizan, Muhammad Qasim; Usman, Muhammad

2016-03-01

UV radiations are high-energy radiations present in sunlight that can damage human skin. Protection against these radiations becomes vital especially in those areas of the globe where UV index is quite high that makes the inhabitants more prone to dangerous effects of UV radiations. Clothing materials are good blockers of UV radiations, particularly when the fabric cover factor is high and/or the fabrics contain suitable UV-blocking finishes. In this study, effect of application of aqueous and methanolic extracts of two different plants, i.e., Achyranthes aspera and Alhagi maurorum on UV protection properties of cotton fabric was investigated. The results showed that the fabric samples treated with extracts of both the plants have excellent UV protection properties as indicated by their ultraviolet protection factor. It was concluded that both the aqueous and methanolic plant extracts are very effective in blocking UVA and UVB radiations, when applied on cotton fabrics. The UV protection performance of Achyranthes aspera extracts was much better as compared to that of Alhagi maurorum, and methanolic extracts of both the plants outperformed the aqueous extracts in terms of UV protection. © 2016 The American Society of Photobiology.

⁹⁹mTc pyrene derivative complex causes double-strand breaks in dsDNA mainly through cluster-mediated indirect effect in aqueous solution.

PubMed

Chung, Wei-Ju; Cui, Yujia; Huang, Feng-Yun J; Tu, Tzu-Hui; Yang, Tzu-Sen; Lo, Jem-Mau; Chiang, Chi-Shiun; Hsu, Ian C

2014-01-01

Radiation therapy for cancer patients works by ionizing damage to nuclear DNA, primarily by creating double-strand breaks (DSB). A major shortcoming of traditional radiation therapy is the set of side effect associated with its long-range interaction with nearby tissues. Low-energy Auger electrons have the advantage of an extremely short effective range, minimizing damage to healthy tissue. Consequently, the isotope ⁹⁹mTc, an Auger electron source, is currently being studied for its beneficial potential in cancer treatment. We examined the dose effect of a pyrene derivative ⁹⁹mTc complex on plasmid DNA by using gel electrophoresis in both aqueous and methanol solutions. In aqueous solutions, the average yield per decay for double-strand breaks is 0.011±0.005 at low dose range, decreasing to 0.0005±0.0003 in the presence of 1 M dimethyl sulfoxide (DMSO). The apparent yield per decay for single-strand breaks (SSB) is 0.04±0.02, decreasing to approximately a fifth with 1 M DMSO. In methanol, the average yield per decay of DSB is 0.54±0.06 and drops to undetectable levels in 2 M DMSO. The SSB yield per decay is 7.2±0.2, changing to 0.4±0.2 in the presence of 2 M DMSO. The 95% decrease in the yield of DSB in DMSO indicates that the main mechanism for DSB formation is through indirect effect, possibly by cooperative binding or clustering of intercalators. In the presence of non-radioactive ligands at a near saturation concentration, where radioactive Tc compounds do not form large clusters, the yield of SSB stays the same while the yield of DSB decreases to the value in DMSO. DSBs generated by ⁹⁹mTc conjugated to intercalators are primarily caused by indirect effects through clustering.

Determination of the antileukemic drug mitoguazone and seven other closely related bis(amidinohydrazones) in human blood serum by high-performance liquid chromatography.

PubMed

Koskinen, M; Elo, H; Lukkari, P; Riekkola, M L

1996-10-11

A reversed-phase (C18) HPLC method with diode-array detection was developed for the separation and determination of methylglyoxal bis(amidinohydrazone) (mitoguazone) and seven closely related aliphatic analogs thereof, namely the bis(amidinohydrazones) of glyoxal, dimethylglyoxal, ethylmethylglyoxal, methylpropylglyoxal, butylmethylglyoxal, diethylglyoxal and dipropylglyoxal. The mobile phase consisted of a non-linear binary gradient of methanol and 0.03 M aqueous sodium acetate buffer (pH 4.3). Good separation of the eight congeners was achieved. On increasing the methanol content of the eluent, the bis(amidinohydrazones) eluted in the order of increasing number of carbon atoms in the side-chains. The method was also applied to the quantitative analysis of the compounds in aqueous solution and, combined with ultrafiltration, for the separation of the eight congeners in spiked human blood serum. A separate simplified method for the quantitative determination of each of the compounds in spiked human blood serum samples was also developed. The methods developed made for the first time possible the simultaneous HPLC analysis of more than one bis(amidinohydrazones). The results obtained indicate that the bis(amidinohydrazones) studied obviously have a distinct tendency to form ion associates with acetate ions and probably also other carboxylate ions in aqueous solution. This aspect may be of biochemical significance, especially concerning the intracellular binding of the compounds. Each one of the compounds studied invariably gave rise to one peak only, this result supporting the theory that the conventional synthesis of each of the compounds gives rise to one geometrical isomer only. This result is completely in agreement with the results of previous proton and carbon NMR spectroscopic as well as X-ray diffraction studies.

Electrochemical CO 2 reduction on Au surfaces: mechanistic aspects regarding the formation of major and minor products

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

Cave, Etosha R.; Montoya, Joseph H.; Kuhl, Kendra P.

In the future, industrial CO 2 electroreduction using renewable energy sources could be a sustainable means to convert CO 2 and water into commodity chemicals at room temperature and atmospheric pressure. This study focuses on the electrocatalytic reduction of CO 2 on polycrystalline Au surfaces, which have high activity and selectivity for CO evolution. Here, we explore the catalytic behavior of polycrystalline Au surfaces by coupling potentiostatic CO 2 electrolysis experiments in an aqueous bicarbonate solution with high sensitivity product detection methods. We observed the production of methanol, in addition to detecting the known products of CO 2 electroreduction onmore » Au: CO, H 2 and formate. We suggest a mechanism that explains Au's evolution of methanol. Specifically, the Au surface does not favor C-O scission, and thus is more selective towards methanol than methane. These insights could aid in the design of electrocatalysts that are selective for CO 2 electroreduction to oxygenates over hydrocarbons.« less

Electrochemical CO 2 reduction on Au surfaces: mechanistic aspects regarding the formation of major and minor products

DOE PAGES

Cave, Etosha R.; Montoya, Joseph H.; Kuhl, Kendra P.; ...

2017-01-06

In the future, industrial CO 2 electroreduction using renewable energy sources could be a sustainable means to convert CO 2 and water into commodity chemicals at room temperature and atmospheric pressure. This study focuses on the electrocatalytic reduction of CO 2 on polycrystalline Au surfaces, which have high activity and selectivity for CO evolution. Here, we explore the catalytic behavior of polycrystalline Au surfaces by coupling potentiostatic CO 2 electrolysis experiments in an aqueous bicarbonate solution with high sensitivity product detection methods. We observed the production of methanol, in addition to detecting the known products of CO 2 electroreduction onmore » Au: CO, H 2 and formate. We suggest a mechanism that explains Au's evolution of methanol. Specifically, the Au surface does not favor C-O scission, and thus is more selective towards methanol than methane. These insights could aid in the design of electrocatalysts that are selective for CO 2 electroreduction to oxygenates over hydrocarbons.« less

Gastroprotective and ulcer healing effects of Piptadeniastrum Africanum on experimentally induced gastric ulcers in rats.

PubMed

Ateufack, Gilbert; Domgnim Mokam, Elisabeth Carol; Mbiantcha, Marius; Dongmo Feudjio, Rostand Breuil; David, Nana; Kamanyi, Albert

2015-07-08

Gastric peptic ulcer is one of the common disorders of gastrointestinal tract, which occur due to an imbalance between the offensive and defensive factors. It is an illness that affects a considerable number of people worldwide. This study was conducted to evaluate the antiulcerogenic and antiulcer effects and recognize the basic mechanism of action of Piptadeniastrum africanum stem bark extracts. The aqueous and methanol extracts of Piptadeniastrum africanum were administered at the doses 125, 250 and 500 mg/kg to evaluate their effects on gastric ulcer induced by the HCl/ethanol mixture, indomethacin and acetic acid in Wistar strain male adult rats, aged between 12 and 16 weeks and weighing between 180 and 220 g. Ranitidine, Maalox and Misoprostol were used as standard drugs. Histopathological examination and nitric oxide level were performed to evaluate the basic mechanism of action of Piptadeniastrum africanum. Phytochemical screening was carried out to identify known phytochemicals present in these extracts. The aqueous and methanol extracts of stem bark of Piptadeniastrum africanum significantly inhibited (p < 0.01) gastric ulceration induced by HCl/ethanol to the percentages of inhibition of 81.38; 98.75 and 100 % for the aqueous extract and then 75.83, 89.76 and 96.52 % for the methanol extract, and with the Indomethacin-induced ulcers, aqueous and methanol extracts of bark of Piptadeniastrum africanum reduce significantly (p < 0.01) induced gastric lesions in rats, with percentage of cure 35.75; 52.33 and 98.58 % for the aqueous extract, and 33.7; 51.97; and 65.93 to the methanol extract. The results revealed a significant reduction of ulcerated surface in both extracts and increase of nitric oxide (NO) level with methanol extract. When compared to methanol extract, aqueous extract showed more pronounced effects, corresponding to percentages of healing of 59. 92; 84.12 and 59.65 % for the aqueous extract; and 70.43; 55.49 and 57.59 % for the methanol extract in the ulcer induced by acetic acid, all at the respective doses of 125, 250 and 500 mg/kg. Histopathological observations also demonstrated curative effect. As such, both extracts were found to exhibit preventive and curative effects through the release of NO and growth factors. This could also be due to the presence of phytochemicals such as alkaloids, flavonoids, phenols and saponins which act as antisecretory agents. Piptadeniastrum africanum stem bark extracts thus have gastroprotective and ulcer healing effects, which could result from their activities by stimulating important cellular mechanisms such as migration and proliferation of epithelial cells that may have a cytoprotective effect by stimulating the release of prostaglandins. These results are required to confirm the ethnopharmacological use of Piptadeniastrum africanum stem bark in the treatment of ulcer.

Use of Moringa oleifera Flower Pod Extract as Natural Preservative and Development of SCAR Marker for Its DNA Based Identification.

PubMed

Gull, Iram; Javed, Attia; Aslam, Muhammad Shahbaz; Mushtaq, Roohi; Athar, Muhammad Amin

2016-01-01

The use of Moringa oleifera as natural food preservative has been evaluated in the present study. In addition, for quality assurance, the study has also been focused on the shelf life of product to authenticate the identification of plant by development of DNA based marker. Among the different extracts prepared from flower pods of Moringa oleifera, methanol and aqueous extract exhibited high antibacterial and antioxidant activity, respectively. The high phenolic contents (53.5 ± 0.169 mg GAE/g) and flavonoid contents (10.9 ± 0.094 mg QE/g) were also recorded in methanol and aqueous extract, respectively. Due to instability of bioactive compounds in aqueous extract, methanol extract is considered as potent natural preservative. The shelf life of methanol extract was observed for two months at 4°C under dark conditions. The developed SCAR primers (MOF217/317/MOR317) specifically amplified a fragment of 317 bp from DNA of Moringa oleifera samples collected from different regions of Punjab province of Pakistan. The methanol extract of Moringa oleifera flower pods has great potential to be used as natural preservative and nutraceutical in food industry.

Use of Moringa oleifera Flower Pod Extract as Natural Preservative and Development of SCAR Marker for Its DNA Based Identification

PubMed Central

Gull, Iram; Javed, Attia; Aslam, Muhammad Shahbaz; Mushtaq, Roohi; Athar, Muhammad Amin

2016-01-01

The use of Moringa oleifera as natural food preservative has been evaluated in the present study. In addition, for quality assurance, the study has also been focused on the shelf life of product to authenticate the identification of plant by development of DNA based marker. Among the different extracts prepared from flower pods of Moringa oleifera, methanol and aqueous extract exhibited high antibacterial and antioxidant activity, respectively. The high phenolic contents (53.5 ± 0.169 mg GAE/g) and flavonoid contents (10.9 ± 0.094 mg QE/g) were also recorded in methanol and aqueous extract, respectively. Due to instability of bioactive compounds in aqueous extract, methanol extract is considered as potent natural preservative. The shelf life of methanol extract was observed for two months at 4°C under dark conditions. The developed SCAR primers (MOF217/317/MOR317) specifically amplified a fragment of 317 bp from DNA of Moringa oleifera samples collected from different regions of Punjab province of Pakistan. The methanol extract of Moringa oleifera flower pods has great potential to be used as natural preservative and nutraceutical in food industry. PMID:27471732

Antinociceptive properties of the aqueous and methanol extracts of the stem bark of Petersianthus macrocarpus (P. Beauv.) Liben (Lecythidaceae) in mice.

PubMed

Bomba, Francis Desire Tatsinkou; Wandji, Bibiane Aimee; Piegang, Basile Nganmegne; Awouafack, Maurice Ducret; Sriram, Dharmarajan; Yogeeswari, Perumal; Kamanyi, Albert; Nguelefack, Telesphore Benoit

2015-11-04

Aqueous maceration from the stem barks of Petersianthus macrocarpus (P. Beauv.) Liben (Lecythidaceae) is taken orally in the central Africa for the management of various ailments, including pain. This work was carried out to evaluate in mice, the antinociceptive effects of the aqueous and methanol extracts of the stem bark of P. macrocarpus. The chemical composition of the aqueous and methanol extracts prepared as cold macerations was determined by high performance liquid chromatography coupled with mass spectrometry (LCMS). The antinociceptive effects of these extracts administered orally at the doses of 100, 200 and 400 mg/kg were evaluated using behavioral pain model induced by acetic acid, formalin, hot-plate, capsaicin and glutamate. The rotarod test was also performed at the same doses. The oral acute toxicity of both extracts was studied at the doses of 800, 1600, 3200 and 6400 mg/kg in mice. The LCMS analysis revealed the presence of ellagic acid as the major constituent in the methanol extract. Both extracts of P. macrocarpus significantly and dose dependently reduced the time and number of writhing induced by acetic acid. They also significantly inhibited the two phases of formalin-induced pain. These effects were significantly inhibited by a pretreatment with naloxone, except for the analgesic activity of the methanol extract at the earlier phase. In addition, nociception induced by hot plate, intraplantar injection of capsaicin or glutamate was significantly inhibited by both extracts. Acute toxicity test showed no sign of toxicity. These results demonstrate that aqueous and methanol extracts of P. macrocarpus are none toxic substances with good central and peripheral antinociceptive effects that are at least partially due to the presence of ellagic acid. These extracts may induce their antinociceptive effect by interfering with opioid, capsaicin and excitatory amino acid pathways. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

High Energy Halogen Chemistry.

DTIC Science & Technology

1978-01-01

underwent addition of triflic acid and of hydrochloric acid . The oxetane was polymerized ~zith phosphorous pentaflucride to ~lve a polymer stable to 2900...in aqueous dioxane . The oxetane was not affected by boron trifluoride etherate In chloroform, or by methanolic solutions of sulfuric or triflic acids ...concentrated hydrochloric acid to give 3-chloro-2-fluoro-2-nitro-l-propanol. NO • i 2 NO2OH CF I + CF SOH— 3 CF SO OCH CCH OH O OH ~ 3 3 2 2~ 2 F NO NO

Mechanism of olefin epoxidation in the presence of a titanium-containing zeolite

NASA Astrophysics Data System (ADS)

Danov, S. M.; Krasnov, V. L.; Sulimov, A. V.; Ovcharova, A. V.

2013-11-01

The effect of the nature of a solvent on the liquid-phase epoxidation of olefins with an aqueous solution of hydrogen peroxide over a titanium-containing zeolite is studied. Butanol-1, butanol-2, propanol-1, isopropanol, methanol, ethanol, water, acetone, methyl ethyl ketone, isobutanol, and tert-butanol are examined as solvents. A mechanism of olefin epoxidation with hydrogen peroxide in an alcohol medium over a titanium-containing zeolite is proposed. Epoxidation reactions involving hydrogen peroxide and different olefins are studied experimentally.

Analysis of phytochemical constituents of Eucalyptus citriodora L. responsible for antifungal activity against post-harvest fungi.

PubMed

Javed, S; Shoaib, A; Mahmood, Z; Mushtaq, S; Iftikhar, S

2012-01-01

In vitro antifungal activity and phytochemical constituents of essential oil, aqueous, methanol and chloroform extract of Eucalyptus citriodora Hook leaves were investigated. A qualitative phytochemical analysis was performed for the detection of alkaloids, cardiac glycosides, flavonoids, saponins, sterols, tannins and phenols. Methanolic extract holds all identified biochemical constituents except for the tannin. While these biochemical constituents were found to be absent in essential oil, aqueous and chloroform extracts with the exception of sterols, cardiac glycosides and phenols in essential oil and sterols and phenols in aqueous and chloroform extracts. Antimycotic activity of four fractions of E. citriodora was investigated through agar-well diffusion method against four post-harvest fungi, namely, Aspergillus flavus Link ex Gray, Aspergillus fumigatus Fres., Aspergillus nidulans Eidam ex Win and Aspergillus terreus Thom. The results revealed maximum fungal growth inhibition by methanolic extract (14.5%) followed by essential oil (12.9%), chloroform extract (10.15%) and aqueous extract (10%).

Photophysical studies on the interaction of acridinedione dyes with universal protein denaturant: guanidine hydrochloride.

PubMed

Kumaran, R; Varalakshmi, T; Malar, E J Padma; Ramamurthy, P

2010-09-01

Photophysical studies of photoinduced electron transfer (PET) and non-PET based acridinedione dyes with guanidine hydrochloride (GuHCl) were carried out in water and methanol. Addition of GuHCl to photoinduced electron transfer (PET) based acridinedione dye (ADR 1) results in a fluorescence enhancement, whereas a non-PET based dye (ADR 2) shows no significant change in the fluorescence intensity and lifetime. Addition of GuHCl to ADR 1 dye in methanol results in single exponential decay behaviour, on the contrary a biexponential decay pattern was observed on the addition of GuHCl in water. Absorption and emission spectral studies of ADR 1 dye interaction with GuHCl reveals that the dye molecule is not in the protonated form in aqueous GuHCl solution, and the dye is confined to two distinguishable microenvironment in the aqueous phase. A large variation in the microenvironment around the dye molecule is created on the addition of GuHCl and this was ascertained by time-resolved area normalized emission spectroscopy (TRANES) and time-resolved emission spectroscopy (TRES). The dye molecule prefers to reside in the hydrophobic microenvironment, rather in the hydrophilic aqueous phase is well emphasized by time-resolved fluorescence lifetime studies. The mechanism of fluorescence enhancement of ADR 1 dye by GuHCl is attributed to the suppression of the PET process occurring through space.

Effects of large volume injection of aliphatic alcohols as sample diluents on the retention of low hydrophobic solutes in reversed-phase liquid chromatography.

PubMed

David, Victor; Galaon, Toma; Aboul-Enein, Hassan Y

2014-01-03

Recent studies showed that injection of large volume of hydrophobic solvents used as sample diluents could be applied in reversed-phase liquid chromatography (RP-LC). This study reports a systematic research focused on the influence of a series of aliphatic alcohols (from methanol to 1-octanol) on the retention process in RP-LC, when large volumes of sample are injected on the column. Several model analytes with low hydrophobic character were studied by RP-LC process, for mobile phases containing methanol or acetonitrile as organic modifiers in different proportions with aqueous component. It was found that starting with 1-butanol, the aliphatic alcohols can be used as sample solvents and they can be injected in high volumes, but they may influence the retention factor and peak shape of the dissolved solutes. The dependence of the retention factor of the studied analytes on the injection volume of these alcohols is linear, with a decrease of its value as the sample volume is increased. The retention process in case of injecting up to 200μL of upper alcohols is dependent also on the content of the organic modifier (methanol or acetonitrile) in mobile phase. Copyright © 2013 Elsevier B.V. All rights reserved.

Detection of traces of triclosan in water

NASA Astrophysics Data System (ADS)

Marques, Inês; Magalhâes-Mota, Gonçalo; Pires, Filipa; Sério, Susana; Ribeiro, Paulo A.; Raposo, Maria

2017-11-01

Triclosan (TCS) is an antibacterial agent widely used in soaps, toothpastes and first-aid products, which presents several drawbacks related with its noxious effects on the biological systems. As this compound is stable and lipophilic, its consumption in large scale is a great deal of concern, particularly because it has been widely found in river water, lake water, sediments, fish and human milk. Therefore, it is urgent to produce an effective, economic, disposable sensor to detect TCS in complex matrixes. This work explores the electronic tongue sensor concept towards the detection of pico-molar concentrations of TCS in aqueous medium. For that an array of sensor devices consisting of bare interdigitated electrodes (IEs) and covered with different layer-by-layer (LBL) films was developed being its response analyzed by impedance spectroscopy. The LbL films were prepared from poly(ethyleneimine) (PEI), graphene oxide (GO), chitosan (Chi), poly[1-[4-(3-carboxy-4-hydroxyphenylazo) benzene sulfonamido]-1,2-ethanediyl, sodium salt] (PAZO) and poly (allylamine hydrochloride) (PAH). Results allowed to select an adequate sensor array to be used for TCS detection in aqueous solutions within the 10-12 M-10-6 M concentrations range, either by using electrical resistance or electrical capacitance at fixed frequencies as key transducing variables. Principal Component Analysis (PCA) data treatment allowed the discrimination of triclosan solution and of methanol aqueous solutions used in TCS solutions preparation, suggesting that the methodology used in this work can be used to detect TCS in complex matrix solutions.

N-Butanol and Aqueous Fractions of Red Maca Methanolic Extract Exerts Opposite Effects on Androgen and Oestrogens Receptors (Alpha and Beta) in Rats with Testosterone-Induced Benign Prostatic Hyperplasia.

PubMed

Fano, Diego; Vásquez-Velásquez, Cinthya; Gonzales-Castañeda, Cynthia; Guajardo-Correa, Emanuel; Orihuela, Pedro A; Gonzales, Gustavo F

2017-01-01

Benign Prostatic Hyperplasia (BPH) affects, worldwide, 50% of 60-year-old men. The Peruvian plant red maca (Lepidium meyenii) inhibits BPH in rodents. This study aimed to determine the effects of methanolic red maca extract and its n-butanol and aqueous fractions on expression of androgen and oestrogen receptors in rats with testosterone enanthate-induced BPH. Thirty-six rats in six groups were studied. Control group received 2 mL of vehicle orally and 0.1 mL of propylene glycol intramuscularly. The second group received vehicle orally and testosterone enanthate (TE) (25 mg/0.1 mL) intramuscularly in days 1 and 7. The other four groups were BPH-induced with TE and received, during 21 days, 3.78 mg/mL of finasteride, 18.3 mg/mL methanol extract of red maca, 2 mg/mL of n-butanol fraction, or 16.3 mg/mL of aqueous fraction from red maca. Treatments with red maca extract and its n-butanol but not aqueous fraction reduced prostate weight similar to finasteride. All maca treated groups restored the expression of ER β , but only the aqueous fraction increased androgen receptors and ER α . In conclusion, butanol fraction of red maca reduced prostate size in BPH by restoring expression of ER β without affecting androgen receptors and ER α . This effect was not observed with aqueous fraction of methanolic extract of red maca.

N-Butanol and Aqueous Fractions of Red Maca Methanolic Extract Exerts Opposite Effects on Androgen and Oestrogens Receptors (Alpha and Beta) in Rats with Testosterone-Induced Benign Prostatic Hyperplasia

PubMed Central

Vásquez-Velásquez, Cinthya

2017-01-01

Benign Prostatic Hyperplasia (BPH) affects, worldwide, 50% of 60-year-old men. The Peruvian plant red maca (Lepidium meyenii) inhibits BPH in rodents. This study aimed to determine the effects of methanolic red maca extract and its n-butanol and aqueous fractions on expression of androgen and oestrogen receptors in rats with testosterone enanthate-induced BPH. Thirty-six rats in six groups were studied. Control group received 2 mL of vehicle orally and 0.1 mL of propylene glycol intramuscularly. The second group received vehicle orally and testosterone enanthate (TE) (25 mg/0.1 mL) intramuscularly in days 1 and 7. The other four groups were BPH-induced with TE and received, during 21 days, 3.78 mg/mL of finasteride, 18.3 mg/mL methanol extract of red maca, 2 mg/mL of n-butanol fraction, or 16.3 mg/mL of aqueous fraction from red maca. Treatments with red maca extract and its n-butanol but not aqueous fraction reduced prostate weight similar to finasteride. All maca treated groups restored the expression of ERβ, but only the aqueous fraction increased androgen receptors and ERα. In conclusion, butanol fraction of red maca reduced prostate size in BPH by restoring expression of ERβ without affecting androgen receptors and ERα. This effect was not observed with aqueous fraction of methanolic extract of red maca. PMID:29375645

Removal of phthalate esters from aqueous solutions by chitosan bead.

PubMed

Chen, Chih-Yu; Chung, Ying-Chien

2006-01-01

Removal of phthalate esters (PAEs) by chitosan bead in aqueous solution was studied. The adsorption isotherms of PAEs by chitosan bead were well described by Freundlich isotherm equations. Results of kinetic experiments indicated that diheptyl phthalate (DHpP) had the highest adsorption capacity (1.52 mg/g) among six PAEs in our research. PAE adsorption efficiency by chitosan bead was examined in both batch and continuous systems, and DHpP attained 74.9% recovery efficiency from chitosan bead by shaking with an equal volume mixture of methanol and water. The recovered chitosan bead was reusable as an adsorbent. The influences of temperature, pH, Ca+2, and NaCl on PAE adsorption were also evaluated to determine performance in different water environments (e.g., groundwater, surface water, and sea water). The results showed that PAE adsorption decreased as temperature increased. From pH experiments it appeared that pH 8.0 was optimal for adsorption. The effect of Ca+2 showed that adsorption efficiency did not change by increasing the concentrations of Ca+2 until 400 mg/L. NaCl coexistence showed an insignificant effect on PAE adsorption. Furthermore, the chitosan bead was also applied to treating the discharge of a plastics plant, and the treatment results resembled those of a laboratory continuous system. This is the first report to use chitosan bead as an adsorbent to adsorb phthalate esters from aqueous solution. These results indicate that the application of chitosan bead is feasible in the aqueous environments of Taiwan.

Integration of C₁ and C₂ Metabolism in Trees.

PubMed

Jardine, Kolby J; Fernandes de Souza, Vinicius; Oikawa, Patty; Higuchi, Niro; Bill, Markus; Porras, Rachel; Niinemets, Ülo; Chambers, Jeffrey Q

2017-09-23

C₁ metabolism in plants is known to be involved in photorespiration, nitrogen and amino acid metabolism, as well as methylation and biosynthesis of metabolites and biopolymers. Although the flux of carbon through the C₁ pathway is thought to be large, its intermediates are difficult to measure and relatively little is known about this potentially ubiquitous pathway. In this study, we evaluated the C₁ pathway and its integration with the central metabolism using aqueous solutions of 13 C-labeled C₁ and C₂ intermediates delivered to branches of the tropical species Inga edulis via the transpiration stream. Delivery of [ 13 C]methanol and [ 13 C]formaldehyde rapidly stimulated leaf emissions of [ 13 C]methanol, [ 13 C]formaldehyde, [ 13 C]formic acid, and 13 CO₂, confirming the existence of the C1 pathway and rapid interconversion between methanol and formaldehyde. However, while [ 13 C]formate solutions stimulated emissions of 13 CO₂, emissions of [ 13 C]methanol or [ 13 C]formaldehyde were not detected, suggesting that once oxidation to formate occurs it is rapidly oxidized to CO₂ within chloroplasts. 13 C-labeling of isoprene, a known photosynthetic product, was linearly related to 13 CO₂ across C₁ and C₂ ([ 13 C₂]acetate and [2- 13 C]glycine) substrates, consistent with reassimilation of C₁, respiratory, and photorespiratory CO₂. Moreover, [ 13 C]methanol and [ 13 C]formaldehyde induced a quantitative labeling of both carbon atoms of acetic acid emissions, possibly through the rapid turnover of the chloroplastic acetyl-CoA pool via glycolate oxidation. The results support a role of the C₁ pathway to provide an alternative carbon source for glycine methylation in photorespiration, enhance CO₂ concentrations within chloroplasts, and produce key C₂ intermediates (e.g., acetyl-CoA) central to anabolic and catabolic metabolism.

Effects of additives on 2,4,6-trinitrotoluene (TNT) removal and its mineralization in aqueous solution by gamma irradiation.

PubMed

Lee, Byungjin; Jeong, Seung-Woo

2009-06-15

The effects of additives (i.e., methanol, EDTA, mannitol, thiourea, nitrous oxide, oxygen and ozone) on gamma irradiation of 2,4,6-trinitrotoluene (TNT) were investigated to elucidate the initial reaction mechanism of TNT degradation and suggest an practical method for complete by-product removal. All additives, except thiourea, significantly increased the TNT removal efficiency by gamma irradiation. The overall results of the additive experiments implied that the TNT decomposition would be initiated by *OH, e(aq)(-), and HO(2*)/O(2*)(-), and also implied that *H did not have any direct effect on the TNT decomposition. Additions of methanol and nitrous oxide were more effective in TNT removal than the other additives, achieving complete removal of TNT at doses below 20 kGy. Total organic carbon (TOC) of the irradiated solution was analyzed to evaluate the degree of TNT mineralization under the additive conditions. TOC under the nitrous oxide addition was removed rapidly, and complete TNT mineralization was thus achieved at 50 kGy. Methanol addition was very effective in the TNT removal, but it was not effective in reduction in TOC. Trinitrobenzene (TNB), oxalic acid and glyoxalic acid were detected as radiolytic organic by-products, while ammonia and nitrate were detected as radiolytic inorganic by-products. The most efficient TNT removal and its mineralization by gamma irradiation would be achieved by supersaturating the solution with nitrous oxide before irradiation.

Removal of heavy metals from aqueous waste streams using surface-modified nanosized TiO{sub 2} photocatalysts.

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

Meshkov, N. K.

1998-08-27

Titanium dioxide (TiO{sub 2}) colloidal particles ({approximately}45{angstrom}) whose surfaces were modified with chelating agents for photocatalytic removal of heavy-metal ions and their subsequent reduction to metallic form were investigated. Experiments were performed on nanoparticle TiO{sub 2} colloids derivatized with bidentate and tridentate ligands (thiolactic acid [TLA], cysteine, and alanine [ALA]) in batch mode in a photoreactor with 254nm light. We used catalysts designed and synthesized for selective and efficient removal of Pb and Cu with and without added hole scavenger (methanol). Parallel experiments also have been carried out in the dark to study metal ion adsorption properties. Solutions have beenmore » filtered to remove TiO{sub 2}, and metal particulates. Both the native solution and the metal deposited on the nanocrystalline TiO{sub 2} particles were analyzed. Results demonstrate that for the case of lead, the most effective TiO{sub 2} surface modifier was TLA (>99% Pb(II) removed from solution). Experiments performed to study Cn removal using TiO{sub 2} colloids modified with alanine showed that copper ions were effectively removed and reduced to metallic form in the presence of methanol.« less

Improvement of Nicotinic Acid and Nicotinamide Analysis in Meats and Meat Products by HPLC and LC-MS/MS with Solid-Phase Extraction.

PubMed

Hiki, Asako; Yamajima, Yukiko; Uematsu, Yoko

2016-01-01

A method for nicotinic acid (NA) and nicotinamide (NAA) analysis in meats was developed. NA and NAA were extracted from meats or meat products with metaphosphate aqueous solution. The extract was cleaned up with an Oasis MCX cartridge. The cartridge was washed with 2% acetic acid (v/v) and acetic acid-methanol solution. NA and NAA were eluted with ammonia-methanol solution. NA and NAA in the eluate were chromatographed on a Scherzo SM-C18 (3.0×150 mm, 3.0 μm) column with 20 mmol/L ammonium acetate containing 0.1% acetic acid-acetonitrile (97 : 3) as a mobile phase and were monitored at 261 nm. Quantification was performed by LC and LC-MS/MS. Calibration curves showed high linearity (correlation coefficient>0.998) between 1-25 μg/mL for LC and LC-MS/MS. Recoveries were 84-108% (CV≦5.8%) by HPLC and 79-105% (CV≦9.0%) by LC-MS/MS. The limit of quantitation for NA was 0.005-0.01 g/kg and that for NAA was 0.01-0.02 g/kg.

Evaluation of in vitro antioxidant properties of methanol and aqueous extracts of Parkinsonia aculeata L. leaves.

PubMed

Sharma, Sonia; Vig, Adarsh Pal

2013-01-01

In the present study, methanol and aqueous extracts of Parkinsonia aculeata L. leaves were prepared and analyzed for phytochemical analysis and antioxidant potential in different in vitro assays. Antioxidant activity was studied using DPPH, CUPRAC, reducing power assay, deoxyribose degradation (site and nonsite specific), ferric reducing antioxidant potential (FRAP), ferric thiocyanate (FTC), thiobarbituric acid (TBA), and molybdate ion reduction, respectively. The total phenolic contents of the methanol and aqueous leaf extract were 39 mg GAE/g and 38 mg GAE/g, whereas flavonoid contents of these extracts were found to be 0.013 mg RE/g and 0.006 mg RE/g, respectively. From the two extracts, the methanol extract shows maximum inhibition (%) of 57.82%, 71.23%, 48.26%, 69.85%, and 52.78% in DPPH, nonsite- and site-specific, FTC, and TBA assays and absorbance of 0.669 and 0.241 in reducing power and CUPRAC assays at the highest concentration tested. UPLC analysis was done to determine the presence of various types of polyphenols present in plant extracts.

Evaluation of In Vitro Antioxidant Properties of Methanol and Aqueous Extracts of Parkinsonia aculeata L. Leaves

PubMed Central

Vig, Adarsh Pal

2013-01-01

In the present study, methanol and aqueous extracts of Parkinsonia aculeata L. leaves were prepared and analyzed for phytochemical analysis and antioxidant potential in different in vitro assays. Antioxidant activity was studied using DPPH, CUPRAC, reducing power assay, deoxyribose degradation (site and nonsite specific), ferric reducing antioxidant potential (FRAP), ferric thiocyanate (FTC), thiobarbituric acid (TBA), and molybdate ion reduction, respectively. The total phenolic contents of the methanol and aqueous leaf extract were 39 mg GAE/g and 38 mg GAE/g, whereas flavonoid contents of these extracts were found to be 0.013 mg RE/g and 0.006 mg RE/g, respectively. From the two extracts, the methanol extract shows maximum inhibition (%) of 57.82%, 71.23%, 48.26%, 69.85%, and 52.78% in DPPH, nonsite- and site-specific, FTC, and TBA assays and absorbance of 0.669 and 0.241 in reducing power and CUPRAC assays at the highest concentration tested. UPLC analysis was done to determine the presence of various types of polyphenols present in plant extracts. PMID:24348173

Pentacyanoiron(II) as an electron donor group for nonlinear optics: medium-responsive properties and comparisons with related pentaammineruthenium(II) complexes.

PubMed

Coe, Benjamin J; Harries, Josephine L; Helliwell, Madeleine; Jones, Lathe A; Asselberghs, Inge; Clays, Koen; Brunschwig, Bruce S; Harris, James A; Garín, Javier; Orduna, Jesús

2006-09-20

In this article, we describe a series of complex salts in which electron-rich {Fe(II)(CN)(5)}(3)(-) centers are coordinated to pyridyl ligands with electron-accepting N-methyl/aryl-pyridinium substituents. These compounds have been characterized by using various techniques including electronic absorption spectroscopy and cyclic voltammetry. Molecular quadratic nonlinear optical (NLO) responses have been determined by using hyper-Rayleigh scattering (HRS) at 1064 nm, and also via Stark (electroabsorption) spectroscopic studies on the intense, visible d --> pi* metal-to-ligand charge-transfer (MLCT) bands. The relatively large static first hyperpolarizabilities, beta(0), increase markedly on moving from aqueous to methanol solutions, accompanied by large red-shifts in the MLCT transitions. Acidification of aqueous solutions allows reversible switching of the linear and NLO properties, as shown via both HRS and Stark experiments. Time-dependent density functional theory and finite field calculations using a polarizable continuum model yield relatively good agreement with the experimental results and confirm the large decrease in beta(0) on protonation. The Stark-derived beta(0) values are generally larger for related {Ru(II)(NH(3))(5)}(2+) complexes than for their {Fe(II)(CN)(5)}(3)(-) analogues, consistent with the HRS data in water. However, the HRS data in methanol show that the stronger solvatochromism of the Fe(II) complexes causes their NLO responses to surpass those of their Ru(II) counterparts upon changing the solvent medium.

Competition between rice (Oryza sativa L.) and (barnyardgrass (Echinochloa crus-galli (L.) P. Beauv.) as affected by methanol foliar application.

PubMed

Rezaeieh, Alireza D; Aminpanah, Hashem; Sadeghi, Seyed M

2015-01-01

Pot experiment was conducted in Iran, to evaluate the effect of methanol on competition between rice (Oryza sativa) and barnyardgrass (Echinochloa crus-galli). The experiment was conducted as a randomized complete block design with a factorial treatment arrangement and three replicates. Factors were two aqueous methanol foliar applications (0, and 14% v/v) and five rice: barnyardgrass ratios (100:0, 75:25, 50:50, 25:6, and 0:100). Replacement series diagrams for aboveground dry weight illustrated that 'Shiroudi' was more competitive than barnyardgrass as averaged across methanol foliar applications. When methanol was not sprayed, the lines for 'Shiroudi' and barnyardgrass intersected at 75:25 rice: barnyardgrass ratio, but when methanol was sprayed at 14% v/v, the lines for 'Shiroudi' and barnyardgrass intersect at the left of the 75:25 rice: barnyardgrass mixture proportion. These indicate that methanol application reduced competitive ability of 'Shiroudi' against barnyardgrass for aboveground biomass accumulation. At the same time, Methanol foliar application significantly reduced the relative crowding coefficient of 'Shiroudi' while simultaneously it significantly increased the relative crowding coefficient of barnyard grass. This indicates that methanol foliar application reduced the competitive ability of 'Shiroudi' against barnyardgrass for shoot biomass accumulation. This experiment illustrated that foliar spray of aqueous methanol can not be recommended for rice under weedy conditions.

Cytotoxicity of different extracts of arial parts of Ziziphus spina-christi on Hela and MDA-MB-468 tumor cells

PubMed Central

Jafarian, Abbas; Zolfaghari, Behzad; Shirani, Kobra

2014-01-01

Background: It has been shown that plants from the family Rhamnaceae possess anticancer activity. In this study, we sought to determine if Ziziphus spina-christi, a species from this family, has cytotoxic effect on cancer cell lines. Materials and Methods: Using maceration method, different extracts of leaves of Z. spina-christi were prepared. Hexane, chloroform, chloroform-methanol (9:1), methanol-water (7:1) methanol, butanol and water were used for extraction, after preliminary phytochemical analyses were done. The cytotoxic activity of the extracts against Hela and MDA-MB-468 tumor cells was evaluated by MTT assay. Briefly, cells were seeded in microplates and different concentrations of extracts were added. After incubation of cells for 72 h, their viability was evaluated by addition of tetrazolium salt solution. After 3 h medium was aspirated, dimethyl sulfoxide was added and absorbance was determined at 540 nm with an ELISA plate reader. Extracts were considered cytotoxic when more than 50% reduction on cell survival was observed. Results: Hexane, chloroform, chloroform-methanol, butanol, methanol-water and aqueous extracts of Z. spina-christi significantly and concentration-dependently reduced viability of Hela and MAD-MB-468 cells. In the both cell lines, chloroform-methanol extract of Z. spina-christi was more potent than the other extracts. Results: From the finding of this study it can be concluded that Z. spina-christi is a good candidate for further study for new cytotoxic agents. PMID:24627846

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

Perera, Aurélien; Mazighi, Redha

Computer simulation studies of aqueous dimethyl sulfoxyde (DMSO) mixtures show micro-heterogeneous structures, just like aqueous alcohol mixtures. However, there is a marked difference in the aggregate structure of water between the two types of systems. While water molecules form multiconnected globular clusters in alcohols, we report herein that the typical water aggregates in aqueous DMSO mixtures are linear, favouring a 2 hydrogen bond structure per water molecule, and for all DMSO mole fractions ranging from 0.1 to 0.9. This linear-aggregate structure produces a particular signature in the water site-site structure factors, in the form of a pre-peak at k ≈more » 0.2–0.8 Å{sup −1}, depending on DMSO concentration. This pre-peak is either absent in other aqueous mixtures, such as aqueous methanol mixtures, or very difficult to see through computer simulations, such as in aqueous-t-butanol mixtures. This difference in the topology of the aggregates explains why the Kirkwood-Buff integrals of aqueous-DMSO mixture look nearly ideal, in contrast with those of aqueous alcohol mixtures, suggesting a connection between the shape of the water aggregates, its fluctuations, and the concentration fluctuations. In order to further study this discrepancy between aqueous DMSO and aqueous alcohol mixture, two models of pseudo-DMSO are introduced, where the size of the sulfur atom is increased by a factor 1.6 and 1.7, respectively, hence increasing the hydrophobicity of the molecule. The study shows that these mixtures become closer to the emulsion type seen in aqueous alcohol mixtures, with more globular clustering of the water molecules, long range domain oscillations in the water-water correlations and increased water-water Kirkwood-Buff integrals. It demonstrates that the local ordering of the water molecules is influenced by the nature of the solute molecules, with very different consequences for structural properties and related thermodynamic quantities. This study illustrates the unique plasticity of water in presence of different types of solutes.« less

Study of the influence of surfactants on the activity coefficients and mass transfer coefficients of methanol in aqueous mixtures by reversed-flow gas chromatography.

PubMed

Kotsalos, Efthimios; Brezovska, Boryana; Sevastos, Dimitrios; Vagena, Artemis; Koliadima, Athanasia; Kapolos, John; Karaiskakis, George

2017-11-17

This work focuses on the influences of surfactants on the activity coefficients, γ, of methanol in binary mixtures with water, as well as on the mass transfer coefficients, k c , for the evaporation of methanol, which is a ubiquitous component in the troposphere, from mixtures of methanol with water at various surfactant's and methanol's concentrations. The technique used is the Reversed-Flow Gas Chromatography (R.F.G.C.), a version of Inverse Gas Chromatography, which allows determining both parameters by performing only one experiment for the k c parameter and two experiments for the γ parameter. The k c and γ values decrease in the presence of the three surfactants used (CTAB, SDS, TRITON X-100) at all methanol's and surfactant's concentrations. The decrease in the methanol's molar fraction, at constant number of surfactant films leads to a decrease in the k c and γ values, while the decrease in the surfactant's concentration, at constant methanol's molar fraction leads to an increase in both the k c and γ parameters. Mass transfer coefficients for the evaporation of methanol at the surfactant films, are also calculated which are approximately between 4 and 5 orders of magnitude larger than the corresponding mass transfer coefficients at the liquid films. Finally, thicknesses of the boundary layer of methanol in the mixtures of methanol with water were determined. The quantities found are compared with those given in the literature or calculated theoretically using various empirical equations. The precision of the R.F.G.C. method for measuring γ and k c parameters is approximately high (94.3-98.0%), showing that R.F.G.C. can be used with success not only for the thermodynamic study of solutions, but also for the interphase transport. Copyright © 2017 Elsevier B.V. All rights reserved.

Uptake of Small Organic Compounds by Sulfuric Acid Aerosols: Dissolution and Reaction

NASA Technical Reports Server (NTRS)

Iraci, L. T.; Michelsen, R. R.; Ashbourn, S. F. M.; Staton, S. J. R.

2003-01-01

To assess the role of oxygenated volatile organic compounds in the upper troposphere and lower stratosphere, the interactions of a series of small organic compounds with low-temperature aqueous sulfuric acid will be evaluated. The total amount of organic material which may be taken up from the gas phase by dissolution, surface layer formation, and reaction during the particle lifetime will be quantified. Our current results for acetaldehyde uptake on 40 - 80 wt% sulfuric acid solutions will be compared to those of methanol, formaldehyde, and acetone to investigate the relationships between chemical functionality and heterogeneous activity. Where possible, equilibrium uptake will be ascribed to component pathways (hydration, protonation, etc.) to facilitate evaluation of other species not yet studied in low temperature aqueous sulfuric acid.

Study on the removal of organic micropollutants from aqueous and ethanol solutions by HAP membranes with tunable hydrophilicity and hydrophobicity.

PubMed

He, Junyong; Li, Yulian; Cai, Xingguo; Chen, Kai; Zheng, Hejing; Wang, Chengming; Zhang, Kaisheng; Lin, Dongyue; Kong, Lingtao; Liu, Jinhuai

2017-05-01

A biocompatible and uniquely defined hydroxyapatite (HAP) adsorption membrane with a sandwich structure was developed for the removal of organic micropollutants for the first time. Both the adsorption and membrane technique were used for the removal of organic micropollutants. The hydrophilicity and hydrophobicity of the HAP adsorbent and membrane were tunable by controlling the surface structure of HAP. The adsorption of organic micropollutants on the HAP adsorbent was studied in batch experiments. The adsorption process was fit with the Freundlich model, while the adsorption kinetics followed the pseudo-second-order model. The HAP membrane could remove organic micropollutants effectively by dynamic adsorption in both aqueous and ethanol solutions. The removal efficiencies of organic micropollutants depended on the solution composition, membrane thickness and hydrophilicity, flow rate, and the initial concentration of organic micropollutants. The adsorption capacities of the HAP membrane with a sandwich structure (membrane thickness was 0.3 mm) were 6700, 6510, 6310, 5960, 5490, 5230, 4980 and 4360 L m -2 for 1-naphthyl amine, 2-naphthol, bisphenol S, propranolol hydrochloride, metolachlor, ethinyl oestradiol, 2,4-dichlorophenol and bisphenol A, respectively, when the initial concentration was 3.0 mg L -1 . The biocompatible HAP adsorption membrane can be easily regenerated by methanol and was thus demonstrated to be a novel concept for the removal of organic micropollutants from both aqueous and organic solutions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hydrogen and methanol exchange processes for (TMP)Rh-OCH3(CH3OH) in binary solutions of methanol and benzene.

PubMed

Sarkar, Sounak; Li, Shan; Wayland, Bradford B

2011-04-18

Tetramesityl porphinato rhodium(III) methoxide ((TMP)Rh-OCH(3)) binds with methanol in benzene to form a 1:1 methanol complex ((TMP)Rh-OCH(3)(CH(3)OH)) (1). Dynamic processes are observed to occur for the rhodium(III) methoxide methanol complex (1) that involve both hydrogen and methanol exchange. Hydrogen exchange between coordinated methanol and methoxide through methanol in solution results in an interchange of the environments for the non-equivalent porphyrin faces that contain methoxide and methanol ligands. Interchange of the environments of the coordinated methanol and methoxide sites in 1 produces interchange of the inequivalent mesityl o-CH(3) groups, but methanol ligand exchange occurs on one face of the porphyrin and the mesityl o-CH(3) groups remain inequivalent. Rate constants for dynamic processes are evaluated by full line shape analysis for the (1)H NMR of the mesityl o-CH(3) and high field methyl resonances of coordinated methanol and methoxide groups in 1. The rate constant for interchange of the inequivalent porphyrin faces is associated with hydrogen exchange between 1 and methanol in solution and is observed to increase regularly with the increase in the mole fraction of methanol. The rate constant for methanol ligand exchange between 1 and the solution varies with the solution composition and fluctuates in a manner that parallels the change in the activation energy for methanol diffusion which is a consequence of solution non-ideality from hydrogen bonded clusters.

Photolysis of oxyfluorfen in aqueous methanol.

PubMed

Chakraborty, Subhasish K; Chakraborty, Savitri; Bhattacharyya, Anjan; Chowdhury, Ashim

2013-01-01

Photolysis of oxyfluorfen, an herbicide of the nitrodiphenyl ether class, was studied in aqueous methanol under UV and sunlight. UV irradiation was carried out in a borosilicate glass photoreactor (containing 250 ppm oxyfluorfen in 50% aqueous methanol) equipped with a quartz filter and 125 watt mercury lamp (maximum output 254 nm) at 25 ± 1°C. Sunlight irradiation was conducted at 28 ± 1°C in borosilicate Erlenmeyer flasks containing 250 ppm oxyfluorfen in 50% aqueous methanol. The samples from both the irradiated conditions were withdrawn at a definite time interval and extracted to measure oxyfluorfen content by gas chromatography-flame ionization detector for rate study. The half-life values were 20 hours and 2.7 days under UV and sunlight exposure, respectively. Photolysis of oxyfluorfen yielded 13 photoproducts of which three were characterized by infrared spectrophotometer and (1)H NMR and (13)C NMR spectroscopy. The rest of the photoproducts were identified by gas chromatography-mass spectrometry (GC-MS) and thin layer chromatography (TLC). An ionization potential 70 eV was used for electron impact-mass spectrometry (EI-MS) and methane was used as reagent gas for chemical ionization-mass spectrometry (CI-MS). Two of the photoproducts were also synthesized for comparison. The main phototransformation pathways of oxyfluorfen involved nitro reduction, dechlorination, and hydrolysis as well as nucleophiles displacement reaction.

Evaluation of Myrtus communis Linn. berries (common myrtle) in experimental ulcer models in rats.

PubMed

Sumbul, Sabiha; Ahmad, Mohd Aftab; Asif, Mohd; Saud, Ibne; Akhtar, Mohd

2010-11-01

The present study was conducted to investigate the protective effect of the dried berries of Myrtus communis L. in gastric ulcer against ethanol, indomethacin and pyloric ligation induced models in Wistar rats. Two doses of aqueous extracts of M. communis (AE( 1) and AE(2)) at the dose 105 and 175 mg/kg, respectively, and methanolic extracts (ME(1) and ME(2)) at the dose of 93 and 154 mg/kg, respectively, were administered orally to animals prior to the exposure of ulcerogens. The parameters taken to assess anti-ulcer activity were ulcer index, gastric juice volume, gastric pH, total acidity, gastric wall mucus and histopathological studies. Oral administration of AE(1) and AE(2) significantly reduced the ulcer index in all models of ulcers. Low dose of aqueous extract and high dose of methanolic extract of M. communis exhibited more significant effect in comparison to omeprazole (standard drug) in ethanol-induced ulcer model. Both the doses of aqueous and methanolic extracts also reduced the gastric juice volume, total acidity and increased the gastric pH and gastric wall mucus content in all the models of ulcers used in the present study. Histopathological examinations of gastric tissues of rats treated with the aqueous and methanolic extracts in indomethacin-induced ulcer exhibited significant ulcer-protective effect at both the dose levels.

Wild Edible Mushrooms from Turkey as Possible Anticancer Agents on HepG2 Cells Together with Their Antioxidant and Antimicrobial Properties.

PubMed

Sadi, Gokhan; Kaya, Abdullah; Yalcin, Hicret Asli; Emsen, Bugrahan; Kocabas, Aytac; Kartal, Deniz Irtem; Altay, Ahmet

2016-01-01

This study was designed to reveal cell growth inhibitory potential of six different edible mushrooms: Ramaria flava, Agrocybe molesta, Volvopluteus gloiocephalus, Lactarius deliciosus, Bovista plumbea, and Tricholoma terreum on HepG2 cells together with their antioxidant and antibacterial power. Methanolic extracts of V gloiocephalus and aqueous extracts of R. flava had the most potential cytotoxic effects over HepG2 cells. The best results for 2,2-diphenyl-1-picrylhydrazyl radical scavenging activities were obtained from both aqueous and methanolic extracts of R. flava. Methanolic extracts of T. terreum (IC50 = 1.62 mg/mL) and aqueous extracts of B. plumbea (IC50 = 0.49 mg/mL) showed maximum metal chelating activity. The highest reducing capacities were observed among the methanolic extracts of R. flava (EC50 = 1.65 mg/mL) and aqueous extracts of B. plumbea (EC50 = 1.71 mg/ mL). High-performance liquid chromatography analysis revealed the presence of many phenolic compounds in macrofungi; gallic acid and p-coumaric acid were the two main phenolics identified in all extracts. Antibacterial studies indicated that all six tested mushrooms showed antibacterial activity on at least three microorganisms. These results indicate that different extracts of the investigated mushrooms have considerable cytotoxic, antioxidant, and antibacterial properties and may be utilized as a promising source of therapeutics.

An extracellular enzyme synthesizes narrow-sized silver nanoparticles in both water and methanol

NASA Astrophysics Data System (ADS)

Rai, Tripti; Panda, Debashis

2015-03-01

Cellulase reduces silver ions in both aqueous and methanolic media yielding stable narrow-sized silver nanoparticles (Ag-NP) at room temperature. The synthesized nanoparticles have been characterized by various spectroscopic, microscopic methods. The redox potentials of tyrosine residues and protein backbone play an instrumental role to reduce the metal ions. The average size of nanoparticles formed in aqueous medium is of 5.04 ± 3.50 nm. Post-synthesis of Ag-NP secondary structure of enzyme is completely lost whereas upon incubation with chemically synthesized Ag-NP a significant gain in secondary structure is observed. Cellulase as a capping ligand stabilizes the silver nanoparticles even in methanol.

Enhanced Photocatalytic Property of Cu Doped Sodium Niobate

DOE PAGES

Xu, Jianbin; Zhang, Feng; Sun, Bingyang; ...

2015-01-01

Here, we investigate the photocatalytic activity of Cu doped NaNbO 3 powder sample prepared by the modified polymer complex method. The photocatalytic activity of hydrogen evolution from methanol aqueous solution was improved by Cu 2.6 at% doping. The photocatalytic degradation of rhodamine B (RhB) under visible light irradiation was enhanced in comparison with pristine NaNbO 3. Cu introduction improved the adsorption property of NaNbO 3, judging from the Fourier transform infrared spectra. Moreover, the ultraviolet light excitation in Cu doped sample would accelerate the mineralized process.

A mechanistic study and computational prediction of iron, cobalt and manganese cyclopentadienone complexes for hydrogenation of carbon dioxide.

PubMed

Ge, Hongyu; Chen, Xiangyang; Yang, Xinzheng

2016-10-13

A series of cobalt and manganese cyclopentadienone complexes are proposed and examined computationally as promising catalysts for hydrogenation of CO 2 to formic acid with total free energies as low as 20.0 kcal mol -1 in aqueous solution. Density functional theory study of the newly designed cobalt and manganese complexes and experimentally reported iron cyclopentadienone complexes reveals a stepwise hydride transfer mechanism with a water or a methanol molecule assisted proton transfer for the cleavage of H 2 as the rate-determining step.

Hydration shell parameters of aqueous alcohols: THz excess absorption and packing density.

PubMed

Matvejev, V; Zizi, M; Stiens, J

2012-12-06

Solvation in water requires minimizing the perturbations in its hydrogen bonded network. Hence solutes distort water molecular motions in a surrounding domain, forming a molecule-specific hydration shell. The properties of those hydration shells impact the structure and function of the solubilized molecules, both at the single molecule and at higher order levels. The size of the hydration shell and the picoseconds time-scale water dynamics retardation are revealed by terahertz (THz) absorption coefficient measurements. Room-temperature absorption coefficient at f = 0.28 [THz] is measured as a function of alcohol concentration in aqueous methanol, ethanol, 1,2-propanol, and 1-butanol solutions. Highly diluted alcohol measurements and enhanced overall measurement accuracy are achieved with a THz absorption measurement technique of nL-volume liquids in a capillary tube. In the absorption analysis, bulk and interfacial molecular domains of water and alcohol are considered. THz ideal and excess absorption coefficients are defined in accordance with thermodynamics mixing formulations. The parameter extraction method is developed based on a THz excess absorption model and hydrated solute molecule packing density representation. First, the hydration shell size is deduced from the hydrated solute packing densities at two specific THz excess absorption nonlinearity points: at infinite alcohol dilution (IAD) and at the THz excess absorption extremum (EAE). Consequently, interfacial water and alcohol molecular domain absorptions are deduced from the THz excess absorption model. The hydration shell sizes obtained at the THz excess absorption extremum are in excellent agreement with other reports. The hydration shells of methanol, ethanol, 1- and 2-propanol consist of 13.97, 22.94, 22.99, and 31.10 water molecules, respectively. The hydration shell water absorption is on average 0.774 ± 0.028 times the bulk water absorption. The hydration shell parameters might shed light on hydration dynamics of biomolecules.

Anticonvulsant activity of Cotyledon orbiculata L. (Crassulaceae) leaf extract in mice.

PubMed

Amabeoku, G J; Green, I; Kabatende, J

2007-05-30

The anticonvulsant activity of Cotyledon orbiculata L. (Crassulaceae) was investigated by studying the effects of both aqueous and methanol extracts of the plant species on seizures induced by pentylenetetrazole, bicuculline, picrotoxin and N-methyl-dl-aspartic in mice. Aqueous extract of Cotyledon orbiculata (50-400mg/kg, i.p.) and methanol extract (100-400mg/kg, i.p.) significantly prolonged the onset of tonic seizures induced by pentylenetetrazole (95mg/kg, i.p.). Methanol extract (400mg/kg, i.p.) also significantly reduced the incidence of the seizures. One hundred to two hundred milligrams/kilogram (i.p.) of aqueous extract of Cotyledon orbiculata significantly delayed the onset of the tonic seizures induced by bicuculline (40mg/kg, i.p.), picrotoxin (12mg/kg, i.p.) and N-methyl-dl-aspartic acid (NMDLA, 400mg/kg, i.p.). Similarly, methanol extract (100-400mg/kg, i.p.) significantly delayed the onset of the tonic seizures induced by bicuculline (40mg/kg, i.p.) and picrotoxin (12mg/kg, i.p.) while 100mg/kg (i.p.) significantly delayed the onset of N-methyl-dl-aspartic acid (NMDLA, 400mg/kg, i.p.)-induced seizures. Methanol extract (200mg/kg, i.p.) significantly reduced the incidence of the seizures induced by bicuculline (40mg/kg, i.p.). Phenobarbitone (12mg/kg, i.p.) and diazepam (0.5mg/kg, i.p.) effectively antagonized only seizures induced by PTZ (95mg/kg, i.p.), bicuculline (40mg/kg, i.p.) and picrotoxin (12mg/kg, i.p.). Phenytoin (30mg/kg, i.p.) did not affect any of the seizures to any significant extent. The data obtained suggest that both aqueous and methanol extracts of Cotyledon orbiculata have anticonvulsant property and may probably be affecting both gabaergic and glutaminergic mechanisms to exert its effect. The phytochemical analysis carried out revealed the presence of cardiac glycosides, saponins, tannins, reducing sugar and triterpene steroids in the plant extract.

Stable Isotope-Assisted Evaluation of Different Extraction Solvents for Untargeted Metabolomics of Plants

PubMed Central

Doppler, Maria; Kluger, Bernhard; Bueschl, Christoph; Schneider, Christina; Krska, Rudolf; Delcambre, Sylvie; Hiller, Karsten; Lemmens, Marc; Schuhmacher, Rainer

2016-01-01

The evaluation of extraction protocols for untargeted metabolomics approaches is still difficult. We have applied a novel stable isotope-assisted workflow for untargeted LC-HRMS-based plant metabolomics , which allows for the first time every detected feature to be considered for method evaluation. The efficiency and complementarity of commonly used extraction solvents, namely 1 + 3 (v/v) mixtures of water and selected organic solvents (methanol, acetonitrile or methanol/acetonitrile 1 + 1 (v/v)), with and without the addition of 0.1% (v/v) formic acid were compared. Four different wheat organs were sampled, extracted and analysed by LC-HRMS. Data evaluation was performed with the in-house-developed MetExtract II software and R. With all tested solvents a total of 871 metabolites were extracted in ear, 785 in stem, 733 in leaf and 517 in root samples, respectively. Between 48% (stem) and 57% (ear) of the metabolites detected in a particular organ were found with all extraction mixtures, and 127 of 996 metabolites were consistently shared between all extraction agent/organ combinations. In aqueous methanol, acidification with formic acid led to pronounced pH dependency regarding the precision of metabolite abundance and the number of detectable metabolites, whereas extracts of acetonitrile-containing mixtures were less affected. Moreover, methanol and acetonitrile have been found to be complementary with respect to extraction efficiency. Interestingly, the beneficial properties of both solvents can be combined by the use of a water-methanol-acetonitrile mixture for global metabolite extraction instead of aqueous methanol or aqueous acetonitrile alone. PMID:27367667

In vitro cytotoxic activity of Aesculus indica against breast adenocarcinoma cell line (MCF-7) and phytochemical analysis.

PubMed

Bibi, Yamin; Nisa, Sobia; Zia, Muhammad; Waheed, Abdul; Ahmed, Sabbir; Chaudhary, M Fayyaz

2012-01-01

Aesculus indica (Linn.) (Sapindaceae) is an ethanobotanically important plant specie traditionally used against rheumatism, skin and vein complaints. Cytotoxic potential of Aesculus indica crude leaf extract and its fractions was investigated against MCF-7 cell line. Crude extract of Aesculus indica was prepared in methanol by maceration technique. Crude extract was fractionated into four organic and one aqueous fraction on polarity basis. MTT assay was used to evaluate the reduction of viability of MCF-7 breast cancer cell line. Cell viability was inhibited by Aesculus indica crude extract in a dose dependent manner ranging from 34.2% at 10 μg/ml to 94% at 500μg/ml. Activity was found in an ascending order from hexane showing 29.8% inhibition to aqueous fraction indicating maximum inhibition, 60%. Phytochemical analysis of crude and fractionated extracts revealed presence of flavonoids, saponins, coumarins and tannins upto varying degrees. Methanol and aqueous fraction of methanol extract of Aesculus indica can be good source of cytotoxic compounds.

Comparative impact of genetically modified and non modified maize (Zea mays L.) on succeeding crop and associated weed.

PubMed

Ibrahim, Muhammad; Ahmed, Naseer; Ullah, Faizan; Shinwari, Zabta Khan; Bano, Asghari

2016-04-01

This research work documents the comparative impact of genetically modified (GM) (insect resistance) and non modified maize (Zea mays L.) on growth and germination of succeeding crop wheat (Triticum aestivum L.) and associated weed (Avena fatua L.). The aqueous extracts of both the GM and non-GM maize exhibited higher phenolic content than that of methanolic extracts. Germination percentage and germination index of wheat was significantly decreased by GM methanolic extract (10%) as well as that of non-GM maize at 3% aqueous extract. Similarly germination percentage of weed (Avena fatua L.) was significantly reduced by application of 3% and 5% methanolic GM extracts. All extracts of GM maize showed non-significant effect on the number of roots, root length and shoot length per plant but 5% and 10% methanolic extracts of non-GM maize significantly increased the number of roots per plant of wheat seedling. Similarly, 10% methanolic extract of GM maize significantly increased the number of roots per plant of weed seedling. Methanolic extracts of GM and non-GM maize (3% and 5%) significantly decreased the protease activity in wheat as compared to untreated control. © The Author(s) 2013.

Inhibitory effects of Caesalpinia sappan on growth and invasion of methicillin-resistant Staphylococcus aureus.

PubMed

Kim, Kang-Ju; Yu, Hyeon-Hee; Jeong, Seung-Il; Cha, Jung-Dan; Kim, Shin-Moo; You, Yong-Ouk

2004-03-01

In the present study, we investigated antimicrobial activity of Caesalpinia sappan against clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) and effect of Caesalpinia sappan extract on the invasion of MRSA to human mucosal fibroblasts (HMFs). Chloroform, n-butanol, methanol, and aqueous extracts of the Caesalpinia sappan showed antimicrobial activity against standard methicillin-sensitive Staphylococcus aureus (MSSA) as well as MRSA. Methanol extract of Caesalpinia sappan demonstrated a higher inhibitory activity than n-butanol, chloroform, and aqueous extracts. In the checkerboard dilution method, methanol extract of Caesalpinia sappan markedly lowered the minimal inhibitory concentrations (MICs) of ampicillin and oxacillin against MRSA. To determine whether methanol extract of Caesalpinia sappan inhibits the MRSA invasion to HMFs, the cells were treated with various sub-MIC concentrations of methanol extract and bacterial invasion was assayed. MRSA invasion was notably decreased in the presence of 20-80 microg/ml of Caesalpinia sappan extract compared to the control group. The effect of Caesalpinia sappan extract on MRSA invasion appeared dose-dependent. These results suggest that methanol extract of Caesalpinia sappan may have antimicrobial activity and the potential to restore the effectiveness of beta-lactam antibiotics against MRSA, and inhibit the MRSA invasion to HMFs.

A Stability-Indicating HPLC Method for the Determination of Nitrosylcobalamin (NO-Cbl), a Novel Vitamin B12 Analog.

PubMed

Dunphy, Michael J; Sysel, Annette M; Lupica, Joseph A; Griffith, Kristie; Sherrod, Taylor; Bauer, Joseph A

2014-04-01

Nitrosylcobalamin (NO-Cbl), a novel vitamin B 12 analog and anti-tumor agent, functions as a biologic 'Trojan horse', utilizing the vitamin B 12 transcobalamin II transport protein and cell surface receptor to specifically target cancer cells. a stability-indicating HPLC method was developed for the detection of NO-Cbl during forced degradation studies. This method utilized an ascentis ® RP-amide (150 mm × 4.6 mm, 5 μm) column at 35 °C with a mobile phase (1.0 mL min -1 ) combining a gradient of methanol and an acetate buffer at pH 6.0. Detection wavelengths of 450 and 254 nm were used to detect corrin and non-corrin-based products, respectively. NO-Cbl, synthesized from hydroxocobalamin and pure nitric oxide gas, was subjected to degradative stress conditions including oxidation, hydrolysis and thermal and radiant energy challenge. The method was validated by assessing linearity, accuracy, precision, detection and quantitation limits and robustness. The method was applied successfully for purity assessment of synthesized NO-Cbl and for the determination of NO-Cbl during kinetic studies in aqueous solution and in solid-state degradation assessments. This HPLC method is suitable for the separation of cobalamins in aqueous and methanolic solutions, for routine detection of NO-Cbl and for purity assessment of synthesized NO-Cbl. additionally, this method has potential application in identification and monitoring of diseases involving altered nitric oxide homeostasis where vitamin B 12 therapy is utilized to scavenge excess nitric oxide, subsequently resulting in the in vivo production of NO-Cbl.

A Stability-Indicating HPLC Method for the Determination of Nitrosylcobalamin (NO-Cbl), a Novel Vitamin B12 Analog

PubMed Central

Dunphy, Michael J.; Sysel, Annette M.; Lupica, Joseph A.; Griffith, Kristie; Sherrod, Taylor

2014-01-01

Nitrosylcobalamin (NO-Cbl), a novel vitamin B12 analog and anti-tumor agent, functions as a biologic ‘Trojan horse’, utilizing the vitamin B12 transcobalamin II transport protein and cell surface receptor to specifically target cancer cells. a stability-indicating HPLC method was developed for the detection of NO-Cbl during forced degradation studies. This method utilized an ascentis® RP-amide (150 mm × 4.6 mm, 5 μm) column at 35 °C with a mobile phase (1.0 mL min−1) combining a gradient of methanol and an acetate buffer at pH 6.0. Detection wavelengths of 450 and 254 nm were used to detect corrin and non-corrin-based products, respectively. NO-Cbl, synthesized from hydroxocobalamin and pure nitric oxide gas, was subjected to degradative stress conditions including oxidation, hydrolysis and thermal and radiant energy challenge. The method was validated by assessing linearity, accuracy, precision, detection and quantitation limits and robustness. The method was applied successfully for purity assessment of synthesized NO-Cbl and for the determination of NO-Cbl during kinetic studies in aqueous solution and in solid-state degradation assessments. This HPLC method is suitable for the separation of cobalamins in aqueous and methanolic solutions, for routine detection of NO-Cbl and for purity assessment of synthesized NO-Cbl. additionally, this method has potential application in identification and monitoring of diseases involving altered nitric oxide homeostasis where vitamin B12 therapy is utilized to scavenge excess nitric oxide, subsequently resulting in the in vivo production of NO-Cbl. PMID:24855323

Separation and characterization of unknown impurities and isomers in flomoxef sodium by LC-IT-TOF MS and study of their negative-ion fragmentation regularities.

PubMed

Yu, Xu; Wang, Fan; Li, Jiani; Shan, Weiguang; Zhu, Bingqi; Wang, Jian

2017-06-05

Thirteen unknown impurities in flomoxef sodium were separated and characterized by liquid chromatography coupled with high resolution ion trap/time-of-flight mass spectrometry (LC-IT-TOF MS)with positive and negative modes of electrospray ionization method for further improvement of official monographs in pharmacopoeias. The fragmentation patterns of impurities in flomoxef in the negative ion mode were studied in detail, and new negative-ion fragmentation regularities were discovered. Chromatographic separation was performed on a Kromasil C18 column (250mm×4.6mm, 5μm). The mobile phase consisted of (A) ammonium formate aqueous solution (10mM)-methanol (84:16, v/v) and (B) ammonium formate aqueous solution (10mM)-methanol (47:53, v/v). In order to determine the m/z values of the molecular ions and formulas of all detected impurities, full scan LC-MS in both positive and negative ion modes was firstly executed to obtain the m/z value of the molecules. Then LC-MS 2 and LC-MS 3 were carried out on target compounds to obtain as much structural information as possible. Complete fragmentation patterns of impurities were studied and used to obtain information about the structures of these impurities. Structures of thirteen unknown degradation products in flomoxef sodium were deduced based on the high resolution MS n data with both positive and negative modes. The forming mechanisms of degradation products in flomoxef sodium were also studied. Copyright © 2017. Published by Elsevier B.V.

Determination of the dissociation constants (pKa) of secondary and tertiary amines in organic media by capillary electrophoresis and their role in the electrophoretic mobility order inversion.

PubMed

Cantu, Marcelo Delmar; Hillebranda, Sandro; Carrilho, Emanuel

2005-03-11

Non-aqueous capillary electrophoresis (NACE) may provide a selectivity enhancement in separations since the analyte dissociation constants (pKa) in organic media are different from those in aqueous solutions. In this work, we have studied the inversion in mobility order observed in the separation of tertiary (imipramine (IMI) and amitryptiline (AMI)) and secondary amines (desipramine (DES) and nortryptiline (NOR)) in water, methanol, and acetonitrile. We have determined the pKa values in those solvents and the variation of dissociation constants with the temperature. From these data, and applying the Van't Hoff equation, we have calculated the thermodynamic parameters deltaH and deltaS. The pKa values found in methanol for DES, NOR, IMI, and AMI were 10.80, 10.79, 10.38, and 10.33, respectively. On the other hand, in acetonitrile an opposite relation was found since the values were 20.60, 20.67, 20.74, and 20.81 for DES, NOR, IMI, and AMI. This is the reason why a migration order inversion is observed in NACE for these solvents. The thermodynamic parameters were evaluated and presented a tendency that can be correlated with that observed for pKa values.

Insecticidal, antimicrobial and antioxidant activities of bulb extracts of Allium sativum.

PubMed

Meriga, Balaji; Mopuri, Ramgopal; MuraliKrishna, T

2012-05-01

To evaluate the insecticidal, antimicrobial and antioxidant activities of bulb extracts of Allium sativum (A. sativum). Dried bulbs of A. sativum were extracted with different solvents and evaluated for insecticidal, antimicrobial and antioxidant activities. Aqueous and methanol extracts showed highest insecticidal activity (mortality rate of 81% and 64% respectively) against the larvae of Spodoptera litura (S. litura) at a concentration of 1 000 ppm. With regard to antimicrobial activity, aqueous extract exhibited antibacterial activity against gram positive (Bacillus subtilis, Staphylococcus aureu,) and gram negative (Escherichia coli and Klebsiella pneumonia) strains and antifungal activity against Candida albicans. While methanol extract showed antimicrobial activity against all the tested micro organisms except two (Staphylococcus aureus and Candida albicans), the extracts of hexane, chloroform and ethyl acetate did not show any anti microbial activity. Minimum inhibitory concentration of aqueous and methanol extracts against tested bacterial and fungal strains was 100-150 μg/mL. Antioxidant activity of the bulb extracts was evaluated in terms of inhibition of free radicals by 2, 2'-diphenly-1-picrylhydrazyl. Aqueous and methanol extracts exhibited strong antioxidant activity (80%-90% of the standard). Antioxidant and antimicrobial activity of A. sativum against the tested organisms therefore, provides scientific basis for its utilization in traditional and folk medicine. Also, our results demonstrated the insecticidal efficacy of A. sativum against S. litura, a polyphagous insect. Copyright © 2012 Hainan Medical College. Published by Elsevier B.V. All rights reserved.

Antidiabetic activity and phytochemical screening of crude extract of Stevia rebaudiana in alloxan-induced diabetic rats

PubMed Central

Kujur, R. S.; Singh, Vishakha; Ram, Mahendra; Yadava, Harlokesh Narayan; Singh, K. K.; Kumari, Suruchi; Roy, B. K.

2010-01-01

Background: Stevia rebaudiana regulates blood sugar, prevents hypertension and tooth decay. Other studies have shown that it has antibacterial as well as antiviral property. Methods: Preliminary phytochemical screening of aqueous, ether and methanolic extracts of S. rebaudiana was done. Acute and sub-acute toxicity were conducted on twenty four Albino rats, divided into one control (Group I) and three treatment groups viz. aqueous extract (Group II), ether extract (Group III) and methanolic extract (Group IV). For the study of antidiabetic effect of S. rebaudiana rats were divided into seven groups (n=6). Diabetes was induced by a single dose of 5% alloxan monohydrate (125 mg/kg, i.p.) after 24 hour fasting.Blood samples were analysed on day 0, 1, 5, 7, 14 and 28. Results: Phytochemical tests showed presence of different kinds of phyto-constituents in aqueous, ether and methanol extract of Stevia rebaudiana leaves. Daily single dose (2.0 g/kg) administration of aqueous extract (A.E.) , ether extract (E.E.) and methanol extract (M.E.) for 28 days of S. rebaudiana could not show any significant change in ALT and AST levels in rats. Blood sugar level was found to be decreased on day 28 in groups of rats treated with A.E., E.E. and M.E. of S. rebaudiana. Conclusion: The extracts of Stevioside rebaudiana could decrease the blood glucose level in diabetic rats in time dependent manner. PMID:21808578

Phenolic compounds from Citrus leaves: antioxidant activity and enzymatic browning inhibition.

PubMed

Khettal, Bachra; Kadri, Nabil; Tighilet, Karim; Adjebli, Ahmed; Dahmoune, Farid; Maiza-Benabdeslam, Fadila

2017-03-01

Background Phenolic compounds from Citrus are known to be a topic of many studies due to their biological properties including antioxidant activity. Methods Methanolic and aqueous extracts were isolated from Citrus leaves of different species (C. clementina, C. limon, C. hamlin, C. navel, C. aurantifolia, C. aurantium and C. grandis) harvested in Algeria. Results The results showed that aqueous extracts of all species are rich in total phenolic compounds and flavonoids (from 68.23 to 125.28 mg GAE/g DM) and (from 11.99 to 46.25 mg QE/g DM) respectively. The methanolic and aqueous extracts were examined for in vitro antioxidant properties using various antioxidant assays. For aqueous extracts, C. limon showed an important DPPH radical scavenging activity (IC50 35.35 µg/mL), and C. clementina exerted the highest ABTS radical scavenging activity (1,174.43 µM ET/g DM) and a significant ferric reducing potential (30.60 mg BHAE/g DM). For methanolic extracts, C. clementina showed the highest antioxidant activity for all the realized assays (IC50 41.85 µg/mL, 378.63 µM ET/g DM and 13.85 mg BHAE/g DM) for DPPH, ABTS radicals scavenging activities and ferric reducing potential respectively. Antiperoxidase and antipolyphenol oxidase activities of these samples were also evaluated. Conclusions In this investigation, the assessment of antiperoxidase activity proved that the leaves extracts of different species were able to inhibit peroxidase activity. However, this inhibition varied with the species and the source of these enzymes. On the other hand, the aqueous extracts of different species showed moderate inhibition of polyphenol oxidase, while no effect on these enzymes was obtained with methanolic extracts.

Chlorophyll degradation in aqueous mediums induced by light and UV-B irradiation: An UHPLC-ESI-MS study

NASA Astrophysics Data System (ADS)

Petrović, Sanja; Zvezdanović, Jelena; Marković, Dejan

2017-12-01

Irreversible chlorophyll degradation induced by continuous white light illumination and UV-B irradiation in the aqueous mediums (with 10%, 30% and 50% of methanol) was investigated using the ultrahigh liquid chromatography coupled with diode array and electrospray ionization mass spectrometry detectors (UHPLC-DAD-ESIMS). The degradation was governed by energy input of photons: higher energy of UV-B irradiation induced faster chlorophyll degradation and accordingly faster products formation in comparison to the white light treatment. Main light- or/and UV-B-induced products of chlorophyll in the aqueous mediums were hydroxy-pheophytin a, pheophytin a and hydroxy-lactone-pheophytin a, accompanied with the corresponding epimers. Chlorophylls aggregation dominant in the aqueous medium with the highest methanol content (50%) play a protective role against the UV-B radiation and white light illumination.

Investigation of DBS electro-oxidation reaction in the aqueous-organic solution of LiClO4.

PubMed

Darlewski, Witold; Popiel, Stanisław; Nalepa, Tomasz; Gromotowicz, Waldemar; Szewczyk, Rafał; Stankiewicz, Romuald

2010-03-15

A process of dibutyl sulphide (DBS) electro-oxidation using electrolysis and cyclic voltamperometry was investigated in water-methanol solution using different electrodes (platinum, boron doped diamond, graphite and glassy carbon). Obtained results indicate that the DBS electro-oxidation process is irreversible in voltamperometric conditions. It was shown that during DBS electrolytic oxidation on Pt, at the low anode potential (1.8 V), DBS was oxidized to sulphoxide and sulphone. Electrolysis at higher potential (up to 3.0 V) resulted in complete DBS oxidation and formation of various products, including: butyric acid, sulphuric acid, butanesulphinic acid, butanesulphonic acid, identified using gas chromatography (GC-AED) and mass spectrometry (GC-MS) methods. (c) 2009 Elsevier B.V. All rights reserved.

CuMnOS Nanoflowers with Different Cu+/Cu2+ Ratios for the CO2-to-CH3OH and the CH3OH-to-H2 Redox Reactions

PubMed Central

Chen, Xiaoyun; Abdullah, Hairus; Kuo, Dong-Hau

2017-01-01

A conservative CO2-Methanol (CH3OH) regeneration cycle, to capture and reutilize the greenhouse gas of CO2 by aqueous hydrogenation for industry-useful CH3OH and to convert aqueous CH3OH solution by dehydrogenation for the clean energy of hydrogen (H2), is demonstrated at normal temperature and pressure (NTP) with two kinds of CuMnOS nanoflower catalysts. The [Cu+]-high CuMnOS led to a CH3OH yield of 21.1 mmol·g−1catal.·h−1 in the CuMnOS-CO2-H2O system and the other [Cu+]-low one had a H2 yield of 7.65 mmol·g−1catal.·h−1 in the CuMnOS-CH3OH-H2O system. The successful redox reactions at NTP rely on active lattice oxygen of CuMnOS catalysts and its charge (hole or electron) transfer ability between Cu+ and Cu2+. The CO2-hydrogenated CH3OH in aqueous solution is not only a fuel but also an ideal liquid hydrogen storage system for transportation application. PMID:28117456

CuMnOS Nanoflowers with Different Cu+/Cu2+ Ratios for the CO2-to-CH3OH and the CH3OH-to-H2 Redox Reactions

NASA Astrophysics Data System (ADS)

Chen, Xiaoyun; Abdullah, Hairus; Kuo, Dong-Hau

2017-01-01

A conservative CO2-Methanol (CH3OH) regeneration cycle, to capture and reutilize the greenhouse gas of CO2 by aqueous hydrogenation for industry-useful CH3OH and to convert aqueous CH3OH solution by dehydrogenation for the clean energy of hydrogen (H2), is demonstrated at normal temperature and pressure (NTP) with two kinds of CuMnOS nanoflower catalysts. The [Cu+]-high CuMnOS led to a CH3OH yield of 21.1 mmol·g-1catal.·h-1 in the CuMnOS-CO2-H2O system and the other [Cu+]-low one had a H2 yield of 7.65 mmol·g-1catal.·h-1 in the CuMnOS-CH3OH-H2O system. The successful redox reactions at NTP rely on active lattice oxygen of CuMnOS catalysts and its charge (hole or electron) transfer ability between Cu+ and Cu2+. The CO2-hydrogenated CH3OH in aqueous solution is not only a fuel but also an ideal liquid hydrogen storage system for transportation application.

CuMnOS Nanoflowers with Different Cu+/Cu2+ Ratios for the CO2-to-CH3OH and the CH3OH-to-H2 Redox Reactions.

PubMed

Chen, Xiaoyun; Abdullah, Hairus; Kuo, Dong-Hau

2017-01-24

A conservative CO 2 -Methanol (CH 3 OH) regeneration cycle, to capture and reutilize the greenhouse gas of CO 2 by aqueous hydrogenation for industry-useful CH 3 OH and to convert aqueous CH 3 OH solution by dehydrogenation for the clean energy of hydrogen (H 2 ), is demonstrated at normal temperature and pressure (NTP) with two kinds of CuMnOS nanoflower catalysts. The [Cu + ]-high CuMnOS led to a CH 3 OH yield of 21.1 mmol·g -1 catal.·h -1 in the CuMnOS-CO 2 -H 2 O system and the other [Cu + ]-low one had a H 2 yield of 7.65 mmol·g -1 catal.·h -1 in the CuMnOS-CH 3 OH-H 2 O system. The successful redox reactions at NTP rely on active lattice oxygen of CuMnOS catalysts and its charge (hole or electron) transfer ability between Cu + and Cu 2+ . The CO 2 -hydrogenated CH 3 OH in aqueous solution is not only a fuel but also an ideal liquid hydrogen storage system for transportation application.

Heterogeneous Chemistry Involving Methanol in Tropospheric Clouds

NASA Technical Reports Server (NTRS)

Tabazadeh, A.; Yokelson, R. J.; Singh, H. B.; Hobbs, P. V.; Crawford, J. H.; Iraci, L. T.

2004-01-01

In this report we analyze airborne measurements to suggest that methanol in biomass burning smoke is lost heterogeneously in clouds. When a smoke plume intersected a cumulus cloud during the SAFARI 2000 field project, the observed methanol gas phase concentration rapidly declined. Current understanding of gas and aqueous phase chemistry cannot explain the loss of methanol documented by these measurements. Two plausible heterogeneous reactions are proposed to explain the observed simultaneous loss and production of methanol and formaldehyde, respectively. If the rapid heterogeneous processing of methanol, seen in a cloud impacted by smoke, occurs in more pristine clouds, it could affect the oxidizing capacity of the troposphere on a global scale.

Phytochemical evaluation, antimicrobial activity, and determination of bioactive components from leaves of Aegle marmelos.

PubMed

Mujeeb, Farina; Bajpai, Preeti; Pathak, Neelam

2014-01-01

The therapeutic value of Aegle marmelos Correa (Rutaceae), commonly known as ''Bael," has been recognized as a component of traditional medication for the treatment of various human ailments. The plant, though, being highly explored, still lacks sufficient evidences for the best variety possessing the highest degree of medicinal values. The present study is focused on phytochemical screening of aqueous and methanolic leaf extracts of 18 varieties/accessions of A. marmelos. The crude extracts of A. marmelos revealed the presence of several biologically active phytochemicals with the highest quantity of alkaloids, flavonoids, and phenols in Pant Aparna variety. The antibacterial efficacy was investigated against pathogenic bacterial strains and the highest inhibitory activity of aqueous extract was obtained against S. epidermidis, whereas methanolic extract was found to be most potent against S. aureus at 40 mg/mL concentration. However, in aqueous : ethanol, the best results were observed against E. aerogenes followed by K. pneumonia and S. epidermidis. The MIC of aqueous and methanol extract of Aegle marmelos ranged from 10 mg/mL to 40 mg/mL whereas in aqueous : ethanol it ranged between 40 mg/mL and 160 mg/mL. The GC-MS analysis revealed the presence of many bioactive compounds such as flavonoids, alcohols, aldehydes, aromatic compounds, fatty acid methyl esters, terpenoids, phenolics, and steroids that can be postulated for antibacterial activity.

Integration of C1 and C2 Metabolism in Trees

PubMed Central

Jardine, Kolby J.; Higuchi, Niro; Bill, Markus; Porras, Rachel; Chambers, Jeffrey Q.

2017-01-01

C1 metabolism in plants is known to be involved in photorespiration, nitrogen and amino acid metabolism, as well as methylation and biosynthesis of metabolites and biopolymers. Although the flux of carbon through the C1 pathway is thought to be large, its intermediates are difficult to measure and relatively little is known about this potentially ubiquitous pathway. In this study, we evaluated the C1 pathway and its integration with the central metabolism using aqueous solutions of 13C-labeled C1 and C2 intermediates delivered to branches of the tropical species Inga edulis via the transpiration stream. Delivery of [13C]methanol and [13C]formaldehyde rapidly stimulated leaf emissions of [13C]methanol, [13C]formaldehyde, [13C]formic acid, and 13CO2, confirming the existence of the C1 pathway and rapid interconversion between methanol and formaldehyde. However, while [13C]formate solutions stimulated emissions of 13CO2, emissions of [13C]methanol or [13C]formaldehyde were not detected, suggesting that once oxidation to formate occurs it is rapidly oxidized to CO2 within chloroplasts. 13C-labeling of isoprene, a known photosynthetic product, was linearly related to 13CO2 across C1 and C2 ([13C2]acetate and [2-13C]glycine) substrates, consistent with reassimilation of C1, respiratory, and photorespiratory CO2. Moreover, [13C]methanol and [13C]formaldehyde induced a quantitative labeling of both carbon atoms of acetic acid emissions, possibly through the rapid turnover of the chloroplastic acetyl-CoA pool via glycolate oxidation. The results support a role of the C1 pathway to provide an alternative carbon source for glycine methylation in photorespiration, enhance CO2 concentrations within chloroplasts, and produce key C2 intermediates (e.g., acetyl-CoA) central to anabolic and catabolic metabolism. PMID:28946627

Integration of C 1 and C 2 Metabolism in Trees

DOE PAGES

Jardine, Kolby J.; Fernandes de Souza, Vinicius; Oikawa, Patty; ...

2017-09-23

C 1 metabolism in plants is known to be involved in photorespiration, nitrogen and amino acid metabolism, as well as methylation and biosynthesis of metabolites and biopolymers. Although the flux of carbon through the C 1 pathway is thought to be large, its intermediates are difficult to measure and relatively little is known about this potentially ubiquitous pathway. In this study, we evaluated the C 1 pathway and its integration with the central metabolism using aqueous solutions of 13C-labeled C 1 and C 2 intermediates delivered to branches of the tropical species Inga edulis via the transpiration stream. Delivery ofmore » [ 13C]methanol and [ 13C]formaldehyde rapidly stimulated leaf emissions of [ 13C]methanol, [ 13C]formaldehyde, [ 13C]formic acid, and 13CO 2, confirming the existence of the C 1 pathway and rapid interconversion between methanol and formaldehyde. However, while [ 13C]formate solutions stimulated emissions of 13CO 2, emissions of [ 13C]methanol or [ 13C]formaldehyde were not detected, suggesting that once oxidation to formate occurs it is rapidly oxidized to CO 2 within chloroplasts. 13C-labeling of isoprene, a known photosynthetic product, was linearly related to 13CO 2 across C 1 and C 2 ([ 13C 2]acetate and [2- 13C]glycine) substrates, consistent with reassimilation of C 1, respiratory, and photorespiratory CO 2. Moreover, [ 13C]methanol and [ 13C]formaldehyde induced a quantitative labeling of both carbon atoms of acetic acid emissions, possibly through the rapid turnover of the chloroplastic acetyl-CoA pool via glycolate oxidation. The results support a role of the C 1 pathway to provide an alternative carbon source for glycine methylation in photorespiration, enhance CO 2 concentrations within chloroplasts, and produce key C 2 intermediates (e.g., acetyl-CoA) central to anabolic and catabolic metabolism.« less

Integration of C 1 and C 2 Metabolism in Trees

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

Jardine, Kolby J.; Fernandes de Souza, Vinicius; Oikawa, Patty

C 1 metabolism in plants is known to be involved in photorespiration, nitrogen and amino acid metabolism, as well as methylation and biosynthesis of metabolites and biopolymers. Although the flux of carbon through the C 1 pathway is thought to be large, its intermediates are difficult to measure and relatively little is known about this potentially ubiquitous pathway. In this study, we evaluated the C 1 pathway and its integration with the central metabolism using aqueous solutions of 13C-labeled C 1 and C 2 intermediates delivered to branches of the tropical species Inga edulis via the transpiration stream. Delivery ofmore » [ 13C]methanol and [ 13C]formaldehyde rapidly stimulated leaf emissions of [ 13C]methanol, [ 13C]formaldehyde, [ 13C]formic acid, and 13CO 2, confirming the existence of the C 1 pathway and rapid interconversion between methanol and formaldehyde. However, while [ 13C]formate solutions stimulated emissions of 13CO 2, emissions of [ 13C]methanol or [ 13C]formaldehyde were not detected, suggesting that once oxidation to formate occurs it is rapidly oxidized to CO 2 within chloroplasts. 13C-labeling of isoprene, a known photosynthetic product, was linearly related to 13CO 2 across C 1 and C 2 ([ 13C 2]acetate and [2- 13C]glycine) substrates, consistent with reassimilation of C 1, respiratory, and photorespiratory CO 2. Moreover, [ 13C]methanol and [ 13C]formaldehyde induced a quantitative labeling of both carbon atoms of acetic acid emissions, possibly through the rapid turnover of the chloroplastic acetyl-CoA pool via glycolate oxidation. The results support a role of the C 1 pathway to provide an alternative carbon source for glycine methylation in photorespiration, enhance CO 2 concentrations within chloroplasts, and produce key C 2 intermediates (e.g., acetyl-CoA) central to anabolic and catabolic metabolism.« less

Tri-metallic PtPdAu mesoporous nanoelectrocatalysts.

PubMed

Li, Chunjie; Wang, Hongjing; Li, Yinghao; Yu, Hongjie; Yin, Shuli; Xue, Hairong; Li, Xiaonian; Xu, You; Wang, Liang

2018-06-22

The design of mesoporous materials with multi-metallic compositions is highly important for various electrocatalytic applications. In this paper, we demonstrate an efficient method to directly fabricate tri-metallic PtPdAu mesoporous nanoparticles (PtPdAu MNs) in a high yield, which is simply performed by heating treatment of the reaction mixture aqueous solution at 40 °C for 4 h. Profiting from its mesoporous structure and multi-metallic components, the as-prepared PtPdAu MNs exhibit enhanced electrocatalytic activities toward both methanol oxidation reaction and oxygen reduction reaction in comparison with bi-metallic PtPd MNs and commercial Pt/C catalyst.

Tri-metallic PtPdAu mesoporous nanoelectrocatalysts

NASA Astrophysics Data System (ADS)

Li, Chunjie; Wang, Hongjing; Li, Yinghao; Yu, Hongjie; Yin, Shuli; Xue, Hairong; Li, Xiaonian; Xu, You; Wang, Liang

2018-06-01

The design of mesoporous materials with multi-metallic compositions is highly important for various electrocatalytic applications. In this paper, we demonstrate an efficient method to directly fabricate tri-metallic PtPdAu mesoporous nanoparticles (PtPdAu MNs) in a high yield, which is simply performed by heating treatment of the reaction mixture aqueous solution at 40 °C for 4 h. Profiting from its mesoporous structure and multi-metallic components, the as-prepared PtPdAu MNs exhibit enhanced electrocatalytic activities toward both methanol oxidation reaction and oxygen reduction reaction in comparison with bi-metallic PtPd MNs and commercial Pt/C catalyst.

Oxytetracycline recovery from aqueous media using computationally designed molecularly imprinted polymers.

PubMed

Rodríguez-Dorado, Rosalía; Carro, Antonia M; Chianella, Iva; Karim, Kal; Concheiro, Angel; Lorenzo, Rosa A; Piletsky, Sergey; Alvarez-Lorenzo, Carmen

2016-09-01

Polymers for recovery/removal of the antimicrobial agent oxytetracycline (OTC) from aqueous media were developed with use of computational design and molecular imprinting. 2-Hydroxyethyl methacrylate, 2-acrylamide-2-methylpropane sulfonic acid (AMPS), and mixtures of the two were chosen according to their predicted affinity for OTC and evaluated as functional monomers in molecularly imprinted polymers and nonimprinted polymers. Two levels of AMPS were tested. After bulk polymerization, the polymers were crushed into particles (200-1000 μm). Pressurized liquid extraction was implemented for template removal with a low amount of methanol (less than 20 mL in each extraction) and a few extractions (12-18 for each polymer) in a short period (20 min per extraction). Particle size distribution, microporous structure, and capacity to rebind OTC from aqueous media were evaluated. Adsorption isotherms obtained from OTC solutions (30-110 mg L(-1)) revealed that the polymers prepared with AMPS had the highest affinity for OTC. The uptake capacity depended on the ionic strength as follows: purified water > saline solution (0.9 % NaCl) > seawater (3.5 % NaCl). Polymer particles containing AMPS as a functional monomer showed a remarkable ability to clean water contaminated with OTC. The usefulness of the stationary phase developed for molecularly imprinted solid-phase extraction was also demonstrated. Graphical Abstract Selection of functional monomers by molecular modeling renders polymer networks suitable for removal of pollutants from contaminated aqueous environments, under either dynamic or static conditions.

The effect of cation:anion ratio in solution on the mechanism of barite growth at constant supersaturation: Role of the desolvation process on the growth kinetics

NASA Astrophysics Data System (ADS)

Kowacz, M.; Putnis, C. V.; Putnis, A.

2007-11-01

The mechanism of barite growth has been investigated in a fluid cell of an Atomic Force Microscope by passing solutions of constant supersaturation ( Ω) but variable ion activity ratio ( r=a/a) over a barite substrate.The observed dependence of step-spreading velocity on solution stoichiometry can be explained by considering non-equivalent attachment frequency factors for the cation and anion. We show that the potential for two-dimensional nucleation changes under a constant thermodynamic driving force due to the kinetics of barium integration into the surface, and that the growth mode changes from preexisting step advancement to island spreading as the cation/anion activity ratio increases. Scanning electron microscopy studies of crystals grown in bulk solutions support our findings that matching the ion ratio in the fluid to that of the crystal lattice does not result in maximum growth and nucleation rates. Significantly more rapid rates correspond to solution stoichiometries where [Ba 2+] is in excess with respect to [ SO42-]. Experiments performed in dilute aqueous solutions of methanol show that even 0.02 molar fraction of organic cosolvent in the growth solution significantly accelerates step growth velocity and nucleation rates (while keeping Ω the same as in the reference solution in water). Our observations suggest that the effect of methanol on barite growth results first of all from reduction of the barrier that prevents the Ba 2+ from reaching the surface and corroborate the hypothesis that desolvation of the cation and of the surface is the rate limiting kinetic process for two-dimensional nucleation and for crystal growth.

Early time excited-state structural evolution of pyranine in methanol revealed by femtosecond stimulated Raman spectroscopy.

PubMed

Wang, Yanli; Liu, Weimin; Tang, Longteng; Oscar, Breland; Han, Fangyuan; Fang, Chong

2013-07-25

To understand chemical reactivity of molecules in condensed phase in real time, a structural dynamics technique capable of monitoring molecular conformational motions on their intrinsic time scales, typically on femtoseconds to picoseconds, is needed. We have studied a strong photoacid pyranine (8-hydroxypyrene-1,3,6-trisulfonic acid, HPTS, pK(a)* ≈ 0) in pure methanol and observed that excited-state proton transfer (ESPT) is absent, in sharp contrast with our previous work on HPTS in aqueous solutions wherein ESPT prevails following photoexcitation. Two transient vibrational marker bands at ~1477 (1454) and 1532 (1528) cm(-1) appear in CH3OH (CD3OD), respectively, rising within the instrument response time of ~140 fs and decaying with 390-470 (490-1400) fs and ~200 ps time constants in CH3OH (CD3OD). We attribute the mode onset to small-scale coherent proton motion along the pre-existing H-bonding chain between HPTS and methanol, and the two decay stages to the low-frequency skeletal motion-modulated Franck-Condon relaxation within ~1 ps and subsequent rotational diffusion of H-bonding partners in solution before fluorescence. The early time kinetic isotope effect (KIE) of ~3 upon methanol deuteration argues active proton motions particularly within the first few picoseconds when coherent skeletal motions are underdamped. Pronounced quantum beats are observed for high-frequency modes consisting of strong phenolic COH rocking (1532 cm(-1)) or H-out-of-plane wagging motions (952 cm(-1)) due to anharmonic coupling to coherent low-frequency modes impulsively excited at ca. 96, 120, and 168 cm(-1). The vivid illustration of atomic motions of HPTS in varying H-bonding geometry with neighboring methanol molecules unravels the multidimensional energy relaxation pathways immediately following photoexcitation, and provides compelling evidence that, in lieu of ESPT, the photoacidity of HPTS promptly activates characteristic low-frequency skeletal motions to search phase space mainly concerning the phenolic end and to efficiently dissipate vibrational energy via skeletal deformation and proton shuttling motions within the intermediate, relatively confined excited-state HPTS-methanol complex on a solvent-dependent dynamic potential energy surface.

Fluorescence spectroscopy of Rhodamine 6G: concentration and solvent effects.

PubMed

Zehentbauer, Florian M; Moretto, Claudia; Stephen, Ryan; Thevar, Thangavel; Gilchrist, John R; Pokrajac, Dubravka; Richard, Katherine L; Kiefer, Johannes

2014-01-01

Rhodamine 6G (R6G), also known as Rhodamine 590, is one of the most frequently used dyes for application in dye lasers and as a fluorescence tracer, e.g., in the area of environmental hydraulics. Knowing the spectroscopic characteristics of the optical emission is key to obtaining high conversion efficiency and measurement accuracy, respectively. In this work, solvent and concentration effects are studied. A series of eight different organic solvents (methanol, ethanol, n-propanol, iso-propanol, n-butanol, n-pentanol, acetone, and dimethyl sulfoxide (DMSO)) are investigated at constant dye concentration. Relatively small changes of the fluorescence spectrum are observed for the different solvents; the highest fluorescence intensity is observed for methanol and lowest for DMSO. The shortest peak wavelength is found in methanol (568 nm) and the longest in DMSO (579 nm). Concentration effects in aqueous R6G solutions are studied over the full concentration range from the solubility limit to highly dilute states. Changing the dye concentration provides tunability between ∼550 nm in the dilute case and ∼620 nm at high concentration, at which point the fluorescence spectrum indicates the formation of R6G aggregates. Copyright © 2013 Elsevier B.V. All rights reserved.

Computational Design of Iron Diphosphine Complexes with Pendant Amines for Hydrogenation of CO2 to Methanol: A Mimic of [NiFe] Hydrogenase.

PubMed

Chen, Xiangyang; Jing, Yuanyuan; Yang, Xinzheng

2016-06-20

Inspired by the active-site structure of the [NiFe] hydrogenase, we have computationally designed the iron complex [P(tBu) 2 N(tBu) 2 )Fe(CN)2 CO] by using an experimentally ready-made diphosphine ligand with pendant amines for the hydrogenation of CO2 to methanol. Density functional theory calculations indicate that the rate-determining step in the whole catalytic reaction is the direct hydride transfer from the Fe center to the carbon atom in the formic acid with a total free energy barrier of 28.4 kcal mol(-1) in aqueous solution. Such a barrier indicates that the designed iron complex is a promising low-cost catalyst for the formation of methanol from CO2 and H2 under mild conditions. The key role of the diphosphine ligand with pendent amine groups in the reaction is the assistance of the cleavage of H2 by forming a Fe-H(δ-) ⋅⋅⋅H(δ+) -N dihydrogen bond in a fashion of frustrated Lewis pairs. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mild oxidation of methane to methanol or acetic acid on supported isolated rhodium catalysts

NASA Astrophysics Data System (ADS)

Shan, Junjun; Li, Mengwei; Allard, Lawrence F.; Lee, Sungsik; Flytzani-Stephanopoulos, Maria

2017-11-01

An efficient and direct method of catalytic conversion of methane to liquid methanol and other oxygenates would be of considerable practical value. However, it remains an unsolved problem in catalysis, as typically it involves expensive or corrosive oxidants or reaction media that are not amenable to commercialization. Although methane can be directly converted to methanol using molecular oxygen under mild conditions in the gas phase, the process is either stoichiometric (and therefore requires a water extraction step) or is too slow and low-yielding to be practical. Methane could, in principle, also be transformed through direct oxidative carbonylation to acetic acid, which is commercially obtained through methane steam reforming, methanol synthesis, and subsequent methanol carbonylation on homogeneous catalysts. However, an effective catalyst for the direct carbonylation of methane to acetic acid, which might enable the economical small-scale utilization of natural gas that is currently flared or stranded, has not yet been reported. Here we show that mononuclear rhodium species, anchored on a zeolite or titanium dioxide support suspended in aqueous solution, catalyse the direct conversion of methane to methanol and acetic acid, using oxygen and carbon monoxide under mild conditions. We find that the two products form through independent pathways, which allows us to tune the conversion: three-hour-long batch-reactor tests conducted at 150 degrees Celsius, using either the zeolite-supported or the titanium-dioxide-supported catalyst, yield around 22,000 micromoles of acetic acid per gram of catalyst, or around 230 micromoles of methanol per gram of catalyst, respectively, with selectivities of 60-100 per cent. We anticipate that these unusually high activities, despite still being too low for commercial application, may guide the development of optimized catalysts and practical processes for the direct conversion of methane to methanol, acetic acid and other useful chemicals.

Mild oxidation of methane to methanol or acetic acid on supported isolated rhodium catalysts

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

Shan, Junjun; Li, Mengwei; Allard, Lawrence F.

An efficient and direct method of catalytic conversion of methane to liquid methanol and other oxygenates would be of considerable practical value. However, it remains an unsolved problem in catalysis, as typically it involves expensive or corrosive oxidants or reaction media(5-8) that are not amenable to commercialization. Although methane can be directly converted to methanol using molecular oxygen under mild conditions in the gas phase, the process is either stoichiometric (and therefore requires a water extraction step) or is too slow and low-yielding to be practical. Methane could, in principle, also be transformed through direct oxidative carbonylation to acetic acid,more » which is commercially obtained through methane steam reforming, methanol synthesis, and subsequent methanol carbonylation on homogeneous catalysts. However, an effective catalyst for the direct carbonylation of methane to acetic acid, which might enable the economical small-scale utilization of natural gas that is currently flared or stranded, has not yet been reported. Here we show that mononuclear rhodium species, anchored on a zeolite or titanium dioxide support suspended in aqueous solution, catalyse the direct conversion of methane to methanol and acetic acid, using oxygen and carbon monoxide under mild conditions. Here, we find that the two products form through independent pathways, which allows us to tune the conversion: three-hour-long batch-reactor tests conducted at 150 degrees Celsius, using either the zeolitesupported or the titanium-dioxide-supported catalyst, yield around 22,000 micromoles of acetic acid per gram of catalyst, or around 230 micromoles of methanol per gram of catalyst, respectively, with selectivities of 60-100 per cent. Finally, we anticipate that these unusually high activities, despite still being too low for commercial application, may guide the development of optimized catalysts and practical processes for the direct conversion of methane to methanol, acetic acid and other useful chemicals.« less

Mild oxidation of methane to methanol or acetic acid on supported isolated rhodium catalysts

DOE PAGES

Shan, Junjun; Li, Mengwei; Allard, Lawrence F.; ...

2017-11-30

An efficient and direct method of catalytic conversion of methane to liquid methanol and other oxygenates would be of considerable practical value. However, it remains an unsolved problem in catalysis, as typically it involves expensive or corrosive oxidants or reaction media(5-8) that are not amenable to commercialization. Although methane can be directly converted to methanol using molecular oxygen under mild conditions in the gas phase, the process is either stoichiometric (and therefore requires a water extraction step) or is too slow and low-yielding to be practical. Methane could, in principle, also be transformed through direct oxidative carbonylation to acetic acid,more » which is commercially obtained through methane steam reforming, methanol synthesis, and subsequent methanol carbonylation on homogeneous catalysts. However, an effective catalyst for the direct carbonylation of methane to acetic acid, which might enable the economical small-scale utilization of natural gas that is currently flared or stranded, has not yet been reported. Here we show that mononuclear rhodium species, anchored on a zeolite or titanium dioxide support suspended in aqueous solution, catalyse the direct conversion of methane to methanol and acetic acid, using oxygen and carbon monoxide under mild conditions. Here, we find that the two products form through independent pathways, which allows us to tune the conversion: three-hour-long batch-reactor tests conducted at 150 degrees Celsius, using either the zeolitesupported or the titanium-dioxide-supported catalyst, yield around 22,000 micromoles of acetic acid per gram of catalyst, or around 230 micromoles of methanol per gram of catalyst, respectively, with selectivities of 60-100 per cent. Finally, we anticipate that these unusually high activities, despite still being too low for commercial application, may guide the development of optimized catalysts and practical processes for the direct conversion of methane to methanol, acetic acid and other useful chemicals.« less

Evidence for Two New Solution States of Ubiquitin by IMS–MS Analysis

PubMed Central

2015-01-01

Ion mobility spectrometry coupled with mass spectrometry (IMS–MS) is used to investigate the populations of different states for ubiquitin in water:methanol solutions. In these experiments, ubiquitin is electrosprayed from 20 water:methanol (100:0 to 5:95, pH = 2) solutions, ranging from native to denaturing conditions. With an increased percentage of methanol in solution, ubiquitin ions ([M + 7H]7+ to [M + 12H]12+) show substantial variations in both charge state distributions and ion mobility distributions. Analysis of these data provides evidence for the existence of five ubiquitin states in solution: the native N state, favored in solutions of 100:0 to 70:30 water:methanol for the +7 and +8 charge states; the more helical A state and a new closely related A′ state, favored in solutions of 70:30 to 5:95 water:methanol for the +9 to +12 charge states; the unfolded U state, populated in 40:60 to 5:95 water:methanol solutions for the +8 to +10 and +12 charge states; and a new low-abundance state termed the B state, observed for 100:0 to 70:30 water:methanol solutions in the +8 to +10 and +12 charge states. The relative abundances for different states in different solutions are determined. The analysis presented here provides insight into how solution structures evolve into anhydrous conformations and demonstrates the utility of IMS–MS methods as a means of characterizing populations of conformers for proteins in solution. PMID:24625065

Antioxidant capacities, phenolic contents, and GC/MS analysis of Rhodiola imbricata Edgew. root extracts from Trans-Himalaya.

PubMed

Tayade, A B; Dhar, P; Sharma, M; Chauhan, R S; Chaurasia, O P; Srivastava, R B

2013-03-01

Our aim was to assess the antioxidant capacities and phenolic constituents of methanol and aqueous extracts of Rhodiola imbricata Edgew. root from Trans-Himalayan cold desert of Ladakh. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging capacity of the root extracts increased in a dose-dependent manner (up to 0.1 mg/mL) and root extract concentrations required for 50% inhibition of radical scavenging effect (IC50 ) were recorded as 0.013 and 0.014 mg/mL (for DPPH) and 0.016 and 0.017 mg/mL (for ABTS) for methanol and aqueous extracts, respectively. The total antioxidant power of the extract was determined by ferric reducing antioxidant power (FRAP) assay. Total polyphenol and phenolic acid content of methanol and aqueous extracts were 112.24, 59.06, 39.02, and 16.95 mg gallic acid equivalent/g of extract, respectively. Total flavonoid and flavonol contents were estimated to be 30.2, 17.67, 20.68, and 7.38 mg quercetin equivalent/g of extract, respectively. In all antioxidant capacity assays, the methanol extract exhibited significantly higher antioxidant capacity than that of aqueous extract due to the presence of significantly higher amount of vital phytoconstitiuents, viz. polyphenol, phenolic acid, and flavonol. GC/MS analysis showed that phytosterols, alkyl halide, phenols, and fatty acid esters were major phytochemical clusters. On the other hand, monoterpenes, fatty acids, tocopherols, aliphatic hydrocarbons, and ethers were found to be present in comparatively less amount in the methanol extract. Hence, our study signifies that this high-altitude medicinal herb could be used as the natural source of antioxidants and supports its use in traditional system of medicine to ameliorate oxidative stress and high-altitude maladies. © 2013 Institute of Food Technologists®

Studies on Wound Healing Activity of Heliotropium indicum Linn. Leaves on Rats.

PubMed

Dash, G K; Murthy, P N

2011-01-01

The petroleum ether, chloroform, methanol, and aqueous extracts of Heliotropium indicum Linn. (Family: Boraginaceae) were separately evaluated for their wound healing activity in rats using excision (normal and infected), incision, and dead space wound models. The effects of test samples on the rate of wound healing were assessed by the rate of wound closure, period of epithelialisation, wound breaking strength, weights of the granulation tissue, determination of hydroxyproline, super oxide dismutase (SOD), catalase, and histopathology of the granulation tissues. Nitrofurazone (0.2% w/w) in simple ointment I. P. was used as reference standard for the activity comparison. The results revealed significant promotion of wound healing with both methanol and aqueous extracts with more promising activity with the methanol extract compared to other extracts under study. In the wound infection model (with S. aureus and P. aeruginosa), the methanol extract showed significant healing activity similar to the reference standard nitrofurazone. Significant increase in the granulation tissue weight, increased hydroxyproline content, and increased activity of SOD and catalase level with the animals treated with methanol extract in dead space wound model further augmented the wound healing potential of H. indicum. The present work substantiates its validity of the folklore use.

Studies on Wound Healing Activity of Heliotropium indicum Linn. Leaves on Rats

PubMed Central

Dash, G. K.; Murthy, P. N.

2011-01-01

The petroleum ether, chloroform, methanol, and aqueous extracts of Heliotropium indicum Linn. (Family: Boraginaceae) were separately evaluated for their wound healing activity in rats using excision (normal and infected), incision, and dead space wound models. The effects of test samples on the rate of wound healing were assessed by the rate of wound closure, period of epithelialisation, wound breaking strength, weights of the granulation tissue, determination of hydroxyproline, super oxide dismutase (SOD), catalase, and histopathology of the granulation tissues. Nitrofurazone (0.2% w/w) in simple ointment I. P. was used as reference standard for the activity comparison. The results revealed significant promotion of wound healing with both methanol and aqueous extracts with more promising activity with the methanol extract compared to other extracts under study. In the wound infection model (with S. aureus and P. aeruginosa), the methanol extract showed significant healing activity similar to the reference standard nitrofurazone. Significant increase in the granulation tissue weight, increased hydroxyproline content, and increased activity of SOD and catalase level with the animals treated with methanol extract in dead space wound model further augmented the wound healing potential of H. indicum. The present work substantiates its validity of the folklore use. PMID:22084720

Preparation of superhydrophobic coatings on zinc as effective corrosion barriers.

PubMed

Liu, Hongqin; Szunerits, Sabine; Xu, Wenguo; Boukherroub, Rabah

2009-06-01

Stable superhydrophobic films with a contact angle of 151 +/- 2 degrees were prepared on zinc substrates by a simple immersion technique into a methanol solution of hydrolyzed 1H,1H,2H,2H-perfluorooctyltrichlorosilane [CF3(CF2)5(CH2)2SiCl3, PFTS] for 5 days at room temperature followed by a short annealing at 130 degrees C in air for 1 h. The superhydrophobic film provides an effective corrosion-resistant coating for the zinc interface when immersed in an aqueous solution of sodium chloride (3% NaCl) for up to 29 days. The corrosion process was investigated by following the change of the water contact angle over time and by electrochemical means. The results are compared to those of unprotected zinc interfaces.

X-ray attenuation coefficients of high-atomic-number, hexanuclear transition metal cluster compounds: a new paradigm for radiographic contrast agents.

PubMed

Mullan, B F; Madsen, M T; Messerle, L; Kolesnichenko, V; Kruger, J

2000-04-01

The purpose of this study was to examine the radiologic attenuation properties of the parent cluster compounds, particularly attenuation as a function of discrete photon energy, before investigating ligand substitutions, which are necessary to improve cluster biocompatibility and to impart desirable physicochemical properties. The linear attenuation coefficients for solutions of the cluster compounds Ta6Br14, K8Ta6O19, and (H3O)2W6Cl14 were determined at 60, 80, 103, 122, and 140 keV from gamma-ray transmission measurements with americium-241, xenon-133, gadolinium-153, cobalt-57, and technetium-99m radioactive sources. Transmission measurements were obtained for a fixed time interval that ensured a statistically accurate count distribution exceeding 20,000 counts through the sample for each trial. On a strictly mole per liter basis, a 0.075 mol/L aqueous solution of K8Ta6O19 showed 1.08 times the attenuation of 0.063 mol/L aqueous iohexol at 60 keV and 3.30 times the attenuation at 80 keV. Similarly, a 0.05 mol/L methanolic solution of (H3O)2W6Cl4 showed 0.96 times (96%) the attenuation of 0.063 mol/L aqueous iohexol at 60 keV but 3.09 times the attenuation of the iohexol solution at 80 keV. Attenuations of 0.063 mol/L aqueous iohexol and 0.0125 mol/L Ta6Br14 (ie, at approximately one-fifth the iohexol concentration) were comparable at greater than 60 keV. These results confirm the theoretic potential for use of early transition metal cluster compounds as radiographic contrast agents. At higher x-ray energies, cluster compounds demonstrate multiplied x-ray attenuation relative to iodinated contrast agents.

Investigation of the pharmaceutical and pharmacological equivalence of different Hawthorn extracts.

PubMed

Vierling, W; Brand, N; Gaedcke, F; Sensch, K H; Schneider, E; Scholz, M

2003-01-01

Seven Hawthorn extracts were tested in isolated guinea pig aorta rings. The effect on noradrenaline- (10 microM) induced contraction was investigated. The extracts were prepared using ethanol (40 to 70% v/v), methanol (40 to 70% v/v), and water as the extraction solvents. The aqueous-alcoholic extracts displayed similar spectra of constituents. They were characterised by similar procyanidin, flavonoid, total vitexin and total phenols content and by similar TLC fingerprint chromatograms. The aqueous extract, however, showed a different fingerprint and a noticeably lower concentration of procyanidins, flavonoids and total phenols but a similar total vitexin content. All 7 extracts had a relaxant effect on the aorta precontracted by noradrenaline and led to relaxations to 44 until 29% of the initial values. The EC50 values of the aqueous-alcoholic extracts varied between 4.16 and 9.8 mg/l. The aqueous extract produced a similarly strong maximal relaxation as the other extracts, but the EC50, at 22.39 mg/l, was markedly higher. The results show that Hawthorn extracts with comparable quality profiles were obtained by using aqueous-alcoholic extraction solvents (40 to 70% ethanol or methanol). The extracts exerted comparable pharmacological effects. When using water as the extraction solvent, both, the spectrum of constituents and the pharmacological effect, deviated remarkably. It is thus possible to obtain bioequivalent extracts with comparable effect profiles by using 40 to 70% ethanol or methanol as the extraction solvent.

High performance methanol-oxygen fuel cell with hollow fiber electrode

NASA Technical Reports Server (NTRS)

Lawson, Daniel D. (Inventor); Ingham, John D. (Inventor)

1983-01-01

A methanol/air-oxygen fuel cell including an electrode formed by open-ended ion-exchange hollow fibers having a layer of catalyst deposited on the inner surface thereof and a first current collector in contact with the catalyst layer. A second current collector external of said fibers is provided which is immersed along with the hollow fiber electrode in an aqueous electrolyte body. Upon passage of air or oxygen through the hollow fiber electrode and introduction of methanol into the aqueous electrolyte, a steady current output is obtained. Two embodiments of the fuel cell are disclosed. In the first embodiment the second metal electrode is displaced away from the hollow fiber in the electrolyte body while in the second embodiment a spiral-wrap electrode is provided about the outer surface of the hollow fiber electrode.

Antimicrobial Activity of Terminalia catappa, Manilkara zapota and Piper betel Leaf Extract.

PubMed

Nair, R; Chanda, Sumitra

2008-01-01

Aqueous and methanol extract of the leaves of Terminalia catappa L., Manilkara zapota L. and Piper betel L. were evaluated for antibacterial activity against 10 Gram positive, 12 Gram negative bacteria and one fungal strain, Candida tropicalis. Piperacillin and gentamicin were used as standards for antibacterial assay, while fluconazole was used as standard for antifungal assay. The three plants showed different degree of activity against the microorganisms investigated. The methanolic extract was considerably more effective than aqueous extract in inhibiting the investigated microbial strains. The most active antimicrobial plant was Piper betel.

Zulu medicinal plants with antibacterial activity.

PubMed

Kelmanson, J E; Jäger, A K; van Staden, J

2000-03-01

Aqueous, methanolic and ethyl acetate extracts of 14 plants used in traditional Zulu medicine for treatment of ailments of an infectious nature were screened for antibacterial activity. Most of the activity detected was against gram-positive bacteria. Tuber bark extracts of Dioscorea sylvatica had activity against gram-negative Escherichia coli and extracts of Dioscorea dregeana, Cheilanthes viridis and Vernonia colorata were active against Pseudomonas aeruginosa. The highest antibacterial activity was found in extracts of C. viridis, D. dregeana, D. silvatica, Melianthus comosus and V. colorata. In general, methanolic extracts exhibited higher activity than aqueous and ethyl acetate extracts.

Stability studies of oxytetracycline in methanol solution

NASA Astrophysics Data System (ADS)

Wang, Wei; Wu, Nan; Yang, Jinghui; Zeng, Ming; Xu, Chenshan; Li, Lun; Zhang, Meng; Li, Liting

2018-02-01

As one kind of typical tetracycline antibiotics, antibiotic residues of oxytetracycline have been frequently detected in many environmental media. In this study, the stability of oxytetracycline in methanol solution was investigated by high-performance liquid chromatography combined with UV-vis (HPLC-UV). The results show that the stability of oxytetracycline in methanol solution is highly related to its initial concentration and the preserved temperature. Under low temperature condition, the solution was more stable than under room temperature preservation. Under the same temperature preservation condition, high concentrations of stock solutions are more stable than low concentrations. The study provides a foundation for preserving the oxytetracycline-methanol solution.

The impact of mixed solvents on the complexation thermodynamics of Eu(III) by simple carboxylate and amino carboxylate ligands

DOE PAGES

Felmy, Heather M.; Bennett, Kevin T.; Clark, Sue B.

2017-05-12

To gain insight on the role of mixed solvents on the thermodynamic driving forces for the complexation between trivalent f-elements and organic ligands, solution phase thermodynamic parameters were determined for Eu(III) complexation with 2-hydroxyisobutyric acid (HIBA) and 2-aminoisobutyric acid (AIBA) in mixed methanol (MeOH)-water and N,N-dimethylformamide (DMF)-water solvents. Included in this study were the determination of mixed solvent autoprotolysis constants (pK α) as well as the thermodynamic formation constants: log β, ΔG, ΔH, and ΔS, for ligand protonation and Eu(III)-ligand complexation utilizing potentiometry and calorimetry techniques. The results presented are conditional thermodynamic values determined at an ionic strength of 1.0more » M NaClO 4 and a temperature of 298 K. It was found that moving from an aqueous solution to a binary aqueous-organic solvent affected all solution equilibria to some degree and that the extent of change depended on both the type of mixed solvent and the ligand in each study. Here, the ability to understand and predict these changes in thermodynamic values as a function of solvent composition provides important information about the chemistry of the trivalent f-elements.« less

The impact of mixed solvents on the complexation thermodynamics of Eu(III) by simple carboxylate and amino carboxylate ligands

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

Felmy, Heather M.; Bennett, Kevin T.; Clark, Sue B.

To gain insight on the role of mixed solvents on the thermodynamic driving forces for the complexation between trivalent f-elements and organic ligands, solution phase thermodynamic parameters were determined for Eu(III) complexation with 2-hydroxyisobutyric acid (HIBA) and 2-aminoisobutyric acid (AIBA) in mixed methanol (MeOH)-water and N,N-dimethylformamide (DMF)-water solvents. Included in this study were the determination of mixed solvent autoprotolysis constants (pK α) as well as the thermodynamic formation constants: log β, ΔG, ΔH, and ΔS, for ligand protonation and Eu(III)-ligand complexation utilizing potentiometry and calorimetry techniques. The results presented are conditional thermodynamic values determined at an ionic strength of 1.0more » M NaClO 4 and a temperature of 298 K. It was found that moving from an aqueous solution to a binary aqueous-organic solvent affected all solution equilibria to some degree and that the extent of change depended on both the type of mixed solvent and the ligand in each study. Here, the ability to understand and predict these changes in thermodynamic values as a function of solvent composition provides important information about the chemistry of the trivalent f-elements.« less

Solvent- and DNA-Controlled Phototriggered Linkage Isomerization in a Ruthenium Sulfoxide Complex Incorporating Dipyrido[3,2-a:2',3'-c]phenazine (dppz).

PubMed

Phapale, Daulat; Ghosh, Rajib; Das, Dipanwita

2017-06-05

A new tris-heteroleptic complex [Ru(bpy)(dppz)(OSO)](ClO 4 ), [1](ClO 4 ) (bpy = 2,2'-bipyridine, dppz = dipyrido[3,2-a:2',3'-c]phenazine and OSO = 2-methylsulfinylbenzoate), was synthesized and characterized to control the photochromic Ru-S → Ru-O linkage isomerization. Details isomerization kinetics studied by UV-visible absorption spectroscopy and cyclic voltammetry revealed that efficient photochromic S → O isomerization and thermal O → S reversal take place in solvents like propylene carbonate (PC), methanol, and dichloromethane. Strikingly, photoisomerization of [1](ClO 4 ) is arrested in water although is active in the analogous compound [Ru(bpy) 2 (OSO)](ClO 4 ). Effective excited state deactivation through dark 3 MLCT state involving dppz ligand of [1](ClO 4 ) switches off photochromism in aqueous medium. Interestingly, the photochromism is activated in aqueous solution in the presence of DNA which shields the dppz localized dark state through intercalation. Ultrafast transient absorption spectroscopic measurement sheds light on the differential behavior of photochromism in aqueous and nonaqueous solvents.

Graphene oxide/MnO2 nanocomposite as destructive adsorbent of nerve-agent simulants in aqueous media

NASA Astrophysics Data System (ADS)

Šťastný, Martin; Tolasz, Jakub; Štengl, Václav; Henych, Jiří; Žižka, David

2017-08-01

Graphene oxide/MnO2 nanocomposite was prepared by thermal hydrolysis of potassium permanganate (KMnO4) and 2-chloroacetamide aqueous solutions with graphene oxide (GO) suspension. The synthesized samples were characterized by specific surface area (BET) and porosity determination (BJH), X-ray Diffraction (XRD) and high-resolution electron microscopes (HRSEM, HRTEM). These nanocomposites were used in an experimental evaluation of their adsorption activity with nerve agent simulants dimethyl methyl phosphonate (DMMP) and triethyl phosphate (TEP) in aqueous media. The nanocomposites exhibited enhanced adsorptive degradation ability compared to pure manganese oxide (MnO2) and GO. The GO amount in the nanocomposites affected their degradation activity substantially. The best adsorption efficiency was observed for samples with moderate GO amount. Three methods were used to observe the mechanism of the nerve-agent simulants deactivation: Gas chromatography with mass spectrometry (GC-MS), High-Performance Liquid Chromatography (HPLC) and in situ Infrared spectroscopy (FTIR). It was shown that the hydrolysis on the surface of prepared nanocomposites yields volatile primary alcohols (methanol and ethanol) as the main hydrolysis products.

Cuscuta arvensis Beyr "Dodder": In Vivo Hepatoprotective Effects Against Acetaminophen-Induced Hepatotoxicity in Rats.

PubMed

Koca-Caliskan, Ufuk; Yilmaz, Ismet; Taslidere, Asli; Yalcin, Funda N; Aka, Ceylan; Sekeroglu, Nazim

2018-05-02

Cuscuta arvensis Beyr. is a parasitic plant, and commonly known as "dodder" in Europe, in the United States, and "tu si zi shu" in China. It is one of the preferred spices used in sweet and savory dishes. Also, it is used as a folk medicine for the treatment particularly of liver problems, knee pains, and physiological hepatitis, which occur notably in newborns and their mothers in the southeastern part of Turkey. The purpose of this study was to investigate the hepatoprotective effects and antioxidant activities of aqueous and methanolic extracts of C. arvensis Beyr. on acetaminophen (APAP)-induced acute hepatotoxicity in rats. The results were supported by subsequent histopathological studies. The hepatoprotective activity of both the aqueous and methanolic extracts at an oral dose of 125 and 250 mg/kg was investigated by observing the reduction levels or the activity of alkaline phosphatase, alkaline transaminase, aspartate aminotransferase, blood urine nitrogen, and total bilirubin content. In vivo antioxidant activity was determined by analyzing the serum superoxide dismutase, malondialdehyde, glutathione, and catalase levels. Chromatographic methods were used to isolate biologically active compounds from the extract, and spectroscopic methods were used for structure elucidation. Both the methanolic and aqueous extracts exerted noticable hepatoprotective and antioxidant effects supporting the folkloric usage of dodder. One of the bioactive compounds was kaempferol-3-O-rhamnoside, isolated and identified from the methanolic extract.

Assessment of antioxidant potential, total phenolics and flavonoids of different solvent fractions of monotheca buxifolia fruit.

PubMed

Jan, Shumaila; Khan, Muhammad Rashid; Rashid, Umbreen; Bokhari, Jasia

2013-10-01

This study was conducted to investigate the antioxidant potential of methanol extract and its derived fractions (hexane, ethyl acetate, butanol, and aqueous) of fruits of Monotheca buxifolia (Falc.) Dc., a locally used fruit in Pakistan. Dried powder of the fruit of M. buxifolia was extracted with methanol and the resultant was fractionated with solvents having escalating polarity; n-hexane, chloroform, ethyl acetate, n-butanol and the residual soluble aqueous fraction. Total phenolic and total flavonoid contents were estimated for the methanol and various fractions. These fractions were also subjected to various in vitro assays to estimate the scavenging activity for 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), superoxide, hydroxyl, hydrogen peroxide and reductive ability for ferric ions and phosphomolybdate assay. The n-butanol, aqueous and methanol fractions possessed high amount of phenolics and flavonoids compared with other fractions, and subsequently showed a pronounced scavenging activity on DPPH, ABTS, superoxide, hydroxyl and hydrogen peroxide radicals and had a potent reductive ability on ferric ion and phosphomolybdate assay. There was a found significant correlation between total phenolic and flavonoid contents and EC50 of DPPH, superoxide, hydrogen peroxide radical and phosphomolybdate assays, whereas a nonsignificant correlation was found with the hydroxyl radical and ABTS radical assay. M. buxifolia fruit can be used as natural antioxidant source to prevent damage associated with free radicals.

Genotoxicity and antigenotoxicity study of aqueous and hydro-methanol extracts of Spondias mombin L., Nymphaea lotus L. and Luffa cylindrical L. using animal bioassays

PubMed Central

Oyeyemi, Ifeoluwa Temitayo; Yekeen, Olaide Maruf; Odusina, Paul Olayinka; Ologun, Taiwo Mary; Ogbaide, Orezimena Michelle; Olaleye, Olayinka Israel

2015-01-01

Spondias mombin (Linn), Nymphaea lotus (Linn) and Luffa cylindrica (Linn) (syn Luffa aegyptiaca Mill) are plants traditionally used as food ingredients and in the management of diseases, including cancer, in Nigeria. Despite the therapeutic potentials attributed to these plants, reports on their genotoxicity are scanty. In this study, the genotoxicity of the aqueous and hydro-methanol extract of these plants was evaluated using mouse bone marrow micronucleus and sperm morphology assays. Antigenotoxicity was assessed by the bone marrow micronucleus test. The highest attainable dose of 5 000 mg/kg according to OECD guidelines was first used to assess acute toxicity of the aqueous and hydro-methanol extracts in Swiss albino mice. For each extract, there were five groups of mice (n=4/group) treated with different concentrations of the extract as against the negative and positive control group for the genotoxicity study. In the antigenotoxicity study, five groups of mice were exposed to five different concentrations of the extracts along with 60 mg/kg of methyl methane sulfonate (MMS), which was used to induce genotoxicity. The mice were administered 0.2 mL of extract per day for 10 days in the genotoxicity and antigenotoxicity groups. Administration of each of the extracts at the concentration of 5 000 mg/kg did not induce acute toxicity in mice. At the concentrations tested, all the extracts, except aqueous S. mombin, increased micronucleated polychromatic erythrocytes. The aqueous and hydro-methanol extracts of N. lotus increased the frequency of aberrant sperm cells. All the extracts were also able to ameliorate MMS induced genotoxicity in bone marrow cells of the exposed mice. The results showed the potential of the extracts to induce somatic and germ cell mutation in male mice. The extracts also ameliorated the genotoxic effect of MMS. PMID:27486380

Genotoxicity and antigenotoxicity study of aqueous and hydro-methanol extracts of Spondias mombin L., Nymphaea lotus L. and Luffa cylindrical L. using animal bioassays.

PubMed

Oyeyemi, Ifeoluwa Temitayo; Yekeen, Olaide Maruf; Odusina, Paul Olayinka; Ologun, Taiwo Mary; Ogbaide, Orezimena Michelle; Olaleye, Olayinka Israel; Bakare, Adekunle A

2015-12-01

Spondias mombin (Linn), Nymphaea lotus (Linn) and Luffa cylindrica (Linn) (syn Luffa aegyptiaca Mill) are plants traditionally used as food ingredients and in the management of diseases, including cancer, in Nigeria. Despite the therapeutic potentials attributed to these plants, reports on their genotoxicity are scanty. In this study, the genotoxicity of the aqueous and hydro-methanol extract of these plants was evaluated using mouse bone marrow micronucleus and sperm morphology assays. Antigenotoxicity was assessed by the bone marrow micronucleus test. The highest attainable dose of 5 000 mg/kg according to OECD guidelines was first used to assess acute toxicity of the aqueous and hydro-methanol extracts in Swiss albino mice. For each extract, there were five groups of mice (n=4/group) treated with different concentrations of the extract as against the negative and positive control group for the genotoxicity study. In the antigenotoxicity study, five groups of mice were exposed to five different concentrations of the extracts along with 60 mg/kg of methyl methane sulfonate (MMS), which was used to induce genotoxicity. The mice were administered 0.2 mL of extract per day for 10 days in the genotoxicity and antigenotoxicity groups. Administration of each of the extracts at the concentration of 5 000 mg/kg did not induce acute toxicity in mice. At the concentrations tested, all the extracts, except aqueous S. mombin, increased micronucleated polychromatic erythrocytes. The aqueous and hydro-methanol extracts of N. lotus increased the frequency of aberrant sperm cells. All the extracts were also able to ameliorate MMS induced genotoxicity in bone marrow cells of the exposed mice. The results showed the potential of the extracts to induce somatic and germ cell mutation in male mice. The extracts also ameliorated the genotoxic effect of MMS.

Aqueous liquid feed organic fuel cell using solid polymer electrolyte membrane

NASA Technical Reports Server (NTRS)

Olah, George A. (Inventor); Surampudi, Subbarao (Inventor); Vamos, Eugene (Inventor); Halpert, Gerald (Inventor); Narayanan, Sekharipuram R. (Inventor); Frank, Harvey A. (Inventor); Prakash, G. K. Surya (Inventor)

1997-01-01

A liquid organic fuel cell is provided which employs a solid electrolyte membrane. An organic fuel, such as a methanol/water mixture, is circulated past an anode of a cell while oxygen or air is circulated past a cathode of the cell. The cell solid electrolyte membrane is preferably fabricated from Nafion.TM.. Additionally, a method for improving the performance of carbon electrode structures for use in organic fuel cells is provided wherein a high surface-area carbon particle/Teflon.TM.-binder structure is immersed within a Nafion.TM./methanol bath to impregnate the electrode with Nafion.TM.. A method for fabricating an anode for use in a organic fuel cell is described wherein metal alloys are deposited onto the electrode in an electro-deposition solution containing perfluorooctanesulfonic acid. A fuel additive containing perfluorooctanesulfonic acid for use with fuel cells employing a sulfuric acid electrolyte is also disclosed. New organic fuels, namely, trimethoxymethane, dimethoxymethane, and trioxane are also described for use with either conventional or improved fuel cells.

Transport of Proteins Dissolved in Organic Solvents Across Biomimetic Membranes

NASA Astrophysics Data System (ADS)

Bromberg, Lev E.; Klibanov, Alexander M.

1995-02-01

Using lipid-impregnated porous cellulose membranes as biomimetic barriers, we tested the hypothesis that to afford effective transmembrane transfer of proteins and nucleic acids, the vehicle solvent should be able to dissolve both the biopolymers and the lipids. While the majority of solvents dissolve one or the other, ethanol and methanol were found to dissolve both, especially if the protein had been lyophilized from an aqueous solution of a pH remote from the protein's isoelectric point. A number of proteins, as well as RNA and DNA, dissolved in these alcohols readily crossed the lipidized membranes, whereas the same biopolymers placed in nondissolving solvents (e.g., hexane and ethyl acetate) or in those unable to dissolve lipids (e.g., water and dimethyl sulfoxide) exhibited little transmembrane transport. The solubility of biopolymers in ethanol and methanol was further enhanced by complexation with detergents and poly(ethylene glycol); significant protein and nucleic acid transport through the lipidized membranes was observed from these solvents but not from water.

Investigation of Ion Transport Mechanisms in NAFION in the Presence of Water and Methanol

DTIC Science & Technology

1996-01-01

uptakes. Zawodzinski et al have determined that the electroosmotic drag coefficient (defined by Zawodzinski as the number of water molecules per H...from the pure water and methanol solutions for comparison to the mixed solutions. These graphs show that solutions with more methanol present have

A Systematic Evaluation of the Extent of Photochemical Processing in Different Types of Secondary Organic Aerosols in the Aqueous Phase

NASA Astrophysics Data System (ADS)

Romonosky, D.; Lee, H.; Epstein, S. A.; Nizkorodov, S.; Laskin, J.; Laskin, A.

2013-12-01

A significant fraction of atmospheric organic compounds are predominantly found in condensed phases, such as organic phase in aerosol particles or aqueous phase in cloud droplets. The oxidation of VOCs followed by the condensation of products into particles was thought to be the main mechanism of organic aerosol (OA) formation. However, in the last several years, scientists have realized that a large fraction, if not the majority of organic particles, is produced through cloud and fog photochemical processes. Many of these organic compounds are photolabile, and can degrade through direct photolysis or indirect photooxidation processes on time scales that are comparable to the typical lifetimes of droplets (hours) and particles (days). We previously reported that compounds in secondary organic aerosol (SOA) from ozonolysis of d-limonene efficiently photodegrade in both organic (Walser et al., 2007) and aqueous phases (Bateman et al., 2011). Significant photolysis was also observed in an aqueous extract of SOA from high-NOx photooxidation of isoprene (Nguyen et al., 2012). More recent experiments studying the response to irradiation of complex aqueous mixtures (as opposed to solutions of isolated compounds) found surprising resilience to photodegradation in aqueous extracts of SOA prepared by photooxidation of alpha-pinene (Romonosky et al., unpublished). We present a systematic investigation of the extent of photochemical processing in different types of SOA from various biogenic and anthropogenic precursors. Chamber- or flowtube-generated SOA is collected on an inert substrate, extracted in a methanol/water solution (70:30), photolyzed in the aqueous solution, and the extent of change in the molecular level composition of the material is assessed with high-resolution mass spectrometry (HR-MS). The outcome of this study will be improved understanding of the role of condensed-phase photochemistry in chemical aging of aerosol particles and cloud droplets. Bateman et al. Photolytic processing of secondary organic aerosols dissolved in cloud droplets. Phys. Chem. Chem. Phys. 2011, 13, 12199. Nguyen et al. Direct aqueous photochemistry of isoprene high-NOx secondary organic aerosol. Phys. Chem. Chem. Phys. 2012, 14, 9702. Walser et al. Photochemical aging of secondary organic aerosol particles generated from the oxidation of d-limonene. J. Phys. Chem. A 2007, 111, 1907.

Anti-inflammatory and analgesic activities of solvent fractions of the leaves of Moringa stenopetala Bak. (Moringaceae) in mice models.

PubMed

Tamrat, Yohannes; Nedi, Teshome; Assefa, Solomon; Teklehaymanot, Tilahun; Shibeshi, Workineh

2017-09-29

Many people still experience pain and inflammation regardless of the available drugs for treatments. In addition, the available drugs have many side effects, which necessitated a quest for new drugs from several sources in which medicinal plants are the major one. This study evaluated the analgesic and anti- inflammatory activity of the solvent fractions of Moringa stenopetala in rodent models of pain and inflammation. Successive soxhlet and maceration were used as methods of extractions using solvents of increasing polarity; chloroform, methanol and water. Swiss albino mice models were used in radiant tail flick latency, acetic acid induced writhing and carrageenan induced paw edema to assess the analgesic and anti-inflammatory activities. The test groups received different doses (100 mg/kg, 200 mg/kg and 400 mg/kg) of the three fractions (chloroform, methanol and aqueous). The positive control groups received morphine (20 mg/kg) or aspirin (100 mg/kg or 150 mg/kg) based on the respective models. The negative control groups received the 10 ml/kg of vehicles (distilled water or 2% Tween 80). In all models, the chloroform fraction had protections only at a dose of 400 mg/kg. However, the methanol and aqueous fraction at all doses have shown significant central and peripheral analgesic activities with a comparable result to the standards. The aqueous and methanol fractions significantly reduced carrageenan induced inflammation in a dose dependent manner, in which the highest reduction of inflammation was observed in aqueous fraction at 400 mg/kg. This study provided evidence on the traditionally claimed uses of the plant in pain and inflammatory diseases, and Moringa stenopetala could be potential source for development of new analgesic and anti-inflammatory drugs.

Analgesic, anti-inflammatory and anti-pyretic activities of Caesalpinia decapetala

PubMed Central

Parveen, Amna; Sajid Hamid Akash, Muhammad; Rehman, Kanwal; Mahmood, Qaisar; Qadir, Muhammad Imran

2014-01-01

Introduction: In many pathological conditions, pain, inflammation and fever are interdependent to each other. Due to the use of synthetic drugs, many unwanted effects usually appear. Various studies have been conducted on Caesalpinia decapetala (C. decapetala) to evaluate its effects in the treatment of various diseases but no sufficient scientific literature is available online to prove its analgesic, anti-inflammatory and anti-pyretic activities. Methods: The analgesic, anti-inflammatory and anti-pyretic activities of 70% aqueous methanolic and n-hexane extracts of C. decapetala was evaluated using Swiss albino mice (20-30 g). Results: The results showed that aqueous methanolic extract of C. decapetala at the dose of 100 mg/kg exhibited significant (p< 0.05) activities in various pain models including acetic acid-induced writhing (18.4 ± 0.53), formalin-induced licking (275 ± 4.18) and hot plate method (2.3 ± 0.0328); whereas,  n-hexane extract showed its effects in acetic acid-induced writhing (20 ± 0.31), formalin-induced licking (293 ± 1.20) and hot plate method (2.224 ± 0.029) compared to the effects observed in control group animals. Similarly, the aqueous methanolic extract of C. decapetala after 2 h of treatment exhibited more significant anti-inflammatory (0.66 ± 0.06) and anti-pyretic (38.81 ± 0.05) activities compared to the control group animals. Conclusion: From the findings of our present study, we concluded that the aqueous methanolic extract of C. decapetala has stronger analgesic, anti-inflammatory and anti-pyretic effects than its n-hexane extract. Further studies are required to investigate the active constituents of C. decapetala that exhibit analgesic, anti-inflammatory and anti-pyretic activities. PMID:24790898

Effects of aqueous, methanolic and chloroform extracts of rhizome and aerial parts of Valeriana officinalis L. on naloxone-induced jumping in morphine-dependent mice.

PubMed

Sharifzadeh, Mohammad; Hadjiakhoondi, Abbas; Khanavi, Mahnaz; Susanabadi, Maryam

2006-06-01

In the present study, the effects of rhizomes and aerial parts extracts of Valeriana officinalis L. on morphine dependence in mice have been investigated. Animals were treated subcutaneously with morphine (50, 50 and 75 mg/kg) three times daily (10 am, 1 pm and 4 pm) for 3 days, and a last dose of morphine (50 mg/kg) was administered on the fourth day. Withdrawal syndrome (jumping) was precipitated by naloxone (5 mg/kg) which was administered intraperitoneally 2 hours after the last dose of morphine. To study the effects of the aqueous, methanolic and chloroform extracts of both aerial parts and rhizome of the V. officinalis L. on naloxone-induced jumping in morphine-dependent animals, 10 injections of morphine (three administrations each day) for dependence and a dose of 5 mg/kg of naloxone for withdrawal induction were employed. Intraperitoneal injection of different doses (1, 5, 25 and 50 mg/kg) of aqueous, methanolic and chloroform extracts of the rhizome of V. officinalis L. 60 minutes before naloxone injection decreased the jumping response dose-dependently. Pre-treatment of animals with different doses (1, 5, 25, 50 and 100 mg/kg) of aqueous and methanolic extracts of aerial parts of V. officinalis L. 60 minutes before naloxone injection caused a significant decrease on naloxone-induced jumping. The chloroform extract of the aerial parts of V. officinalis L. did not show any significant changes on jumping response in morphine-dependent animals. It is concluded that the extracts of V. officinalis L. could affect morphine withdrawal syndrome via possible interactions with inhibitory neurotransmitters in nervous system.

Inhibition of the growth and development of mosquito larvae of Culex quinquefasciatus (Diptera: Culicidae) treated with extract from leaves of Pseudocalymma alliaceum (Bignonaceae).

PubMed

Granados-Echegoyen, Carlos; Pérez-Pacheco, Rafael; Soto-Hernández, Marcos; Ruiz-Vega, Jaime; Lagunez-Rivera, Luicita; Alonso-Hernandez, Nancy; Gato-Armas, Rene

2014-08-01

To determine larvicidal activity of the essential oil, hydrolat and botanical extracts derived from leaves of Pseudocalymma alliaceum on mosquito larvae of Culex quinquefasciatus. Groups of twenty larvae were used in the larvicidal assays. The mortality, relative growth rate, the larval and pupal duration and viability was estimated. The essential oil was analyzed by solid phase microextraction using gas chromatography coupled to mass spectrometry. Essential oil at 800 ppm showed larvicidal activity at 24 h with lethal values of LC50 and LC90 of 267.33 and 493.63 ppm. The hydrolat at 20% and 10% on 2nd stage larvae showed 100% effectiveness after 24 h. The aqueous extract at 10% had a relative growth index of 0.58, while the ethanolic and methanolic extract obtained values of 0.76 and 0.70 and control reached 0.99. Larvae treated with 10% of methanol, ethanol and aqueous extract showed a reduction in larval duration of 5.00, 2.20 and 4.35 days; ethanol extract at 1% provoke decrease of 2.40 days in the development and exhibited an increment of 3.30 days when treated with 0.01%. Aqueous, ethanol and methanol extracts at 10% reduced in 6.15, 3.42 and 5.57 days pupal development. The main compounds were diallyl disulfide (50.05%), diallyl sulfide (11.77%) and trisulfide di-2-propenyl (10.37%). The study demonstrated for the first time, the larvicidal activity of the essential oil and hydrolat of Pseudocalymma alliaceum; aqueous, ethanol and methanol extracts inhibited the normal growth and development of mosquito larvae, prolonging and delaying larval and pupal duration. Copyright © 2014 Hainan Medical College. Published by Elsevier B.V. All rights reserved.

Determination of the solubility of inorganic salts by headspace gas chromatography.

PubMed

Chai, X S; Zhu, J Y

2003-05-09

This work reports a novel method for determination of salt solubility using headspace gas chromatography. A very small amount of volatile compound (such as methanol) is added in the studied solution. Due to the molecular interaction in the solution, the vapor-liquid equilibrium (VLE) partitioning coefficient of the volatile species will change with different salt contents in the solution. Therefore, the concentration of volatile species in the vapor phase is proportional to the salt concentration in the liquid phase, which can be easily determined by headspace gas chromatography. Until the salt concentration in the solution is saturated, the concentration of volatile compound in the vapor phase will continue to increase further and a breakpoint will appear on the VLE curve. The solubility of the salts can be determined by the identification of the breakpoint. It was found that the measured solubility of sodium carbonate and sodium sulfate in aqueous solutions is slightly higher (about 6-7%) than those reported in the literature method. The present method can be easily applied to industrial solution systems.

Barium isotope fractionation during the experimental transformation of aragonite to witherite and of gypsum to barite, and the effect of ion (de)solvation.

PubMed

Böttcher, Michael E; Neubert, Nadja; von Allmen, Katja; Samankassou, Elias; Nägler, Thomas F

2018-06-01

In this study, we present the experimental results for stable barium (Ba) isotope fractionation ( 137 Ba/ 134 Ba) during the transformation of aragonite (CaCO 3 ) and gypsum (CaSO 4 ·2H 2 O) in Ba-bearing aqueous solution to witherite (BaCO 3 ) and barite (BaSO 4 ), respectively. The process was studied at three temperatures between 4 and 60 °C. In all cases, the transformation leads to a relative enrichment of the lighter 134 Ba isotope in the solid compared to the aqueous solution, with 137/134 Ba enrichment factors between -0.11 and -0.17 ‰ for BaCO 3 , and -0.21 and -0.26 ‰ for BaSO 4 . The corresponding mass-dependent 138/134 Ba enrichment factors are -0.15 to -0.23 ‰ for BaCO 3 , and -0.28 to -0.35 ‰ for BaSO 4 . The magnitude of isotope fractionation is within the range of recent reports for witherite and barite formation, as well as trace Ba incorporation into orthorhombic aragonite, and no substantial impact of temperature can be found between 4 and 80 °C. In previous studies, ion (de)solvation has been suggested to impact both the crystallization process of Ba-bearing solids and associated Ba isotope fractionation. Precipitation experiments of BaSO 4 and BaCO 3 using an methanol-containing aqueous solution indicate only a minor effect of ion and crystal surface (de)solvation on the overall Ba isotope fractionation process.

Simple and portable low frequency lock-in amplifier designed for photoacoustic measurements and its application to thermal effusivity determination in liquids

NASA Astrophysics Data System (ADS)

Ortega-Robles, Emmanuel; Cruz-Orea, Alfredo; Elías-Viñas, David

2018-03-01

The lock-in amplifier is a very useful instrument for observing very small signals under adverse signal-to-noise conditions. In this work, we describe a simple and portable lock-in amplifier designed to be used in photoacoustic measurements. The device was used to measure the thermal effusivity of eight different liquid samples (distilled water, glycerol, acetone, ethanol, 2-propanol, chloroform, hexane, and methanol), as well as the effusivity of acetone in aqueous solution at distinct concentrations, giving good results. The instrument has a bandwidth of 10 Hz-10 kHz and a sensitivity of 1 μV.

Zinc oxide films chemically grown onto rigid and flexible substrates for TFT applications

NASA Astrophysics Data System (ADS)

Suchea, M.; Kornilios, N.; Koudoumas, E.

2010-10-01

This contribution presents some preliminary results regarding the use of a chemical route for the growth of good quality ZnO thin films that can be used for the fabrication of thin film transistors (TFTs). The films were grown at rather low temperature (60 °C) on glass and PET substrates using non-aqueous (zinc acetate dihydrate in methanol) precursor solution and their surface morphology, crystalline structure, optical transmittance and electrical characteristics were studied. The study indicated that good quality films with desirable ZnO structure onto rigid and flexible substrates can be obtained, using a simple, cheap, low temperature chemical growth method.

Determination of preservatives in cosmetics, cleaning agents and pharmaceuticals using fast liquid chromatography.

PubMed

Baranowska, Irena; Wojciechowska, Iwona; Solarz, Natalia; Krutysza, Ewa

2014-01-01

This paper reports the development of a method for simultaneously determining five preservatives in cosmetics, cleaning agents and pharmaceuticals by fast liquid chromatography. Methylisothiazolinone, methylchloroisothiazolinone, benzyl alcohol, sodium benzoate and methylparaben were separated on a Chromolith Fast Gradient reversed-phase 18e column using gradient elution with acetonitrile and a 0.1% aqueous solution of formic acid, with a run time of 3 min. The preparation of solid and liquid samples included ultrasonic extraction with methanol with recoveries ranging from 69 to 119%. The developed method was used to analyze samples of cosmetics (66 samples), cleaning agents (five samples) and pharmaceutical industry products (17 samples).

Synthesis and characterization of oxytetracycline imprinted magnetic polymer for application in food

NASA Astrophysics Data System (ADS)

Aggarwal, Sneha; Rajput, Yudhishthir Singh; Singh, Gulab; Sharma, Rajan

2016-02-01

Magnetic imprinted polymer was prepared by polymerization of methacrylate and ethyleneglycoldimethacrylate in the presence of oxytetracycline on the surface of iron magnetite. Selectivity of prepared polymer was calculated from ratio of partition coefficient of oxytetracycline for imprinted and non- imprinted polymer in water, acetonitrile, methanol and at different pH in aqueous buffer. pH of solvent exhibited pronounced effect on selectivity. Selectivity at pH 7.0, 6.0 and 5.0 was 36.0, 2.25 and 1.61 fold higher than at pH 4.0. Imprinted polymer was not selective for oxytetracycline in methanol. However, selectivity in water and acetonitrile was 19.42 and 2.86, respectively. Oxytetracycline did bind to imprinted polymer in water or aqueous buffer (pH 7.0) and could be eluted with methanol. Prepared polymer extracted 75-80 % oxytetracycline from water, honey and egg white.

Combinatorial effects of charge characteristics and hydrophobicity of silk fibroin on the sorption and release of charged dyes.

PubMed

Wongpanit, Panya; Rujiravanit, Ratana

2012-01-01

The present study was designed to examine the influence of the charge characteristics of silk fibroin on the sorption and release of charged dyes by varying the pH values of the sorption and release media as well as types of charged dyes. Negatively charged dyes (phenol red and chromotrope 2R) and positively charged dyes (crystal violet and indoine blue) were used as the model compounds. Silk fibroin films were prepared by using a solution casting technique. The prepared films were then treated with an aqueous methanol solution or annealed with water to control their conformation. The sorption behavior of the model compounds made by the methanol-treated and water-annealed silk fibroin films was investigated. Compared to the water- annealed silk fibroin films, a higher hydrophobicity of the methanol-treated silk fibroin films caused a higher sorption of the hydrophobic dyes. The dye molecules had a fairly high affinity to the silk fibroin film, even though the dye and the matrix possessed the same charge. However, in the presence of two charged groups in a single dye molecule, the electrostatic repulsion become more dominant. Stronger interaction was observed when the charges of the film and the dye were opposite. The results of dye sorption and release experiments showed that the degree of synergism or competition between electrostatic and hydrophobic interactions directly depended on the charges and chemical structure of the dye molecules and the environmental pH conditions of the existing silk fibroin film.

Changes in total phenol, flavonoid contents and anti-Lactobacillus activity of Callisia fragrans due to extraction solvent

NASA Astrophysics Data System (ADS)

Le, Thom; Cao, Diem Kieu; Pham, Thanh Vy; Huynh, Tan Dat; Ta, Nhat Thuy Anh; Nguyen, Ngoc Thao Linh; Nguyen, Huu Thanh; Le, Hue Huong; Bui, Anh Vo; Truong, Dieu-Hien

2018-04-01

Callisia fragrans is a wonder herb with many medicinal properties such as burn, dental diseases, cancer diseases and arthritis in folk medicine. It is noted that the phytochemical constituents and antimicrobial activity of traditional plants depend on not only the extracting method but also the solvent used for extraction. In this study, the effect of five extraction solvents (i.e., distilled water, 80% methanol, 80% ethanol, 80% ethyl acetate, and 80% chloroform) on yield, total phenolic content (TPC) and total flavonoid content (TFC) of Callisia leaves was determined. Besides, changes in anti-Lactobacillus fermentum activity of C. fragrans freeze-dried extract was also evaluated using disk-diffusion method. The recovery percentage of extractable yield of fresh leaves are ranged from 11.93% w/w for distilled water extract to 16.60% w/w for aqueous ethanol extracts. The yield of 80% aqueous methanol extract (16.27% w/w) is only slightly less than that of the ethanol extract. Significant differences were observed among TPC and TFC obtaining by 80% methanol (0.0522% and 0.0335% w/w, respectively) compared to other solvents (p < 0.05). TPC and TFC of C. fragrans extracts increase in the following order: distilled water < 80% chloroform < 80% ethyl acetate < 80% ethanol < 80% methanol. The results revealed that 80% aqueous methanol Calissia extracts has moderate inhibition (9.0 mm of inhibition zone for 1.5 mg/mL of extracts) of L. fermentum compared to standard antibacterial agent. Based on the study results, it can be concluded that the yield, TPC and TFC of C. frgrans extract varied with the extracting solvent. It also showed that Callisia extracts can prevent dental caries by inhibiting the growth of L. fermentum, towards new insights for treatment of dental caries.

Antimicrobial Activity and Brine Shrimp Lethality Bioassay of the Leaves Extract of Dillenia indica Linn.

PubMed

Apu, As; Muhit, Ma; Tareq, Sm; Pathan, Ah; Jamaluddin, Atm; Ahmed, M

2010-01-01

The crude methanolic extract of Dillenia indica Linn. (Dilleniaceae) leaves has been investigated for the evaluation of antimicrobial and cytotoxic activities. Organic solvent (n-hexane, carbon tetrachloride and chloroform) fractions of methanolic extract and methanolic fraction (aqueous) were screened for their antimicrobial activity by disc diffusion method. Besides, the fractions were screened for cytotoxic activity using brine shrimp (Artemia salina) lethality bioassay. Among the four fractions tested, n-hexane, carbon tetrachloride, and chloroform fractions showed moderate antibacterial and antifungal activity compared to standard antibiotic, kanamycin. The average zone of inhibition was ranged from 6 to 8 mm at a concentration of 400 µg/disc. But the aqueous fraction was found to be insensitive to microbial growth. Compared to vincristine sulfate (with LC(50) of 0.52 µg/ ml), n-hexane and chloroform fractions demonstrated a significant cytotoxic activity (having LC(50) of 1.94 µg/ml and 2.13 µg/ml, respectively). The LC(50) values of the carbon tetrachloride and aqueous fraction were 4.46 µg/ml and 5.13 µg/ ml, respectively. The study confirms the moderate antimicrobial and potent cytotoxic activities of Dillenia indica leaves extract and therefore demands the isolation of active principles and thorough bioassay.

Semiconductor-Based, Solar-Driven Photochemical Cells for Fuel Generation from Carbon Dioxide in Aqueous Solutions.

PubMed

Yehezkeli, Omer; Bedford, Nicholas M; Park, Eunsol; Ma, Ke; Cha, Jennifer N

2016-11-23

There has been active interest to identify new methods to reduce CO 2 into usable fuel sources. In this work, we demonstrate two types of photo-electrochemical cells (PECs) that photoreduce CO 2 directly to formate in aqueous solutions both in the presence and absence of external bias or additional electron sources. The photocathodes were either a CuFeO 2 /CuO electrode or a bilayer of CdTe on NiO, whereas the photoanode was a bilayer of NiO x on CdS. The PECs were characterized by using both electrochemistry and spectroscopy, and the products formed from CO 2 reduction were characterized and quantified by using 1 H NMR spectroscopy and ESI-MS. In addition, an organohydride catalyst was tested in conjunction with the PECs, which not only showed a significant gain of 85 times in CO 2 reduction (27 μm formate without the catalyst, 2.3 mm formate with it) compared to the NiO/CdTe photocathode system but could also generate methanol under an external bias (10 μm). © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Application of fingerprint chromatogram in quality assessment of apple cider].

PubMed

Xu, Kangzhen; Song, Jirong; Ren, Yinghui; Ma, Haixia; Huang, Jie; Du, Xiaodan

2007-01-01

Fingerprints of 14 apple cider samples from different manufacturers were studied using high performance liquid chromatography (HPLC) with an electrochemical detector (ECD). The analysis was carried out on a Zorbax SB-C18 column at 30 degrees C with 2% (v/v) methanol aqueous solution-4% (v/v) acetic acid aqueous solution as mobile phase at a flow rate of 0.8 mL/min. The electrochemical detector was set at 0.7 V. By calculating the relative retention times of certain peaks with chlorogenic acid as the reference standard, 8 common peaks in the samples were analyzed. Relative retention times for the common peaks of various samples were calculated, and the similarities of all the samples were figured out through each peak area with the vectorial angle cosine method and correlative coefficient method. The results indicated that apple cider products of the same manufacturer have good similarity, with the similarities greater than 92.7%. According to this experiment, effectual microcosmic information for apple cider analysis was gained through HPLC and ECD. Moreover, this test method will help the analysis and the control of product quality, the development of new products and the establishment of trade standard.

Degradation of phorbol 12,13-diacetate in aqueous solution by gamma irradiation

NASA Astrophysics Data System (ADS)

Kongmany, Santi; Furuta, Masakazu; Matsuura, Hiroto; Okuda, Shuichi; Imamura, Kiyoshi; Maeda, Yasuaki

2014-12-01

Phorbol esters (PEs) are highly toxic compounds that cause skin irritation, inflammation, and tumor promotion upon contact with humans or animals. These compounds are naturally present in Jatropha curcas L. To promote the use of J. curcas seed oil in bio-diesel production industries and reduce environmental concerns, it is necessary to find methods of degrading PEs. In this study, the degradation of phorbol 12,13-diacetate (PDA), as a representative PE, in aqueous solution at a concentration of 10 mg/L by 60Co-γ-irradiation was investigated. The results demonstrate that PDA was effectively degraded by this treatment and the degradation efficiency increased with the absorbed dose within the range of 0.5-3 kGy. Complete degradation of PDA was achieved at a dose of 3 kGy. In the presence of radical scavengers (i.e., methanol, tert-butanol, 2-propanol), reactive species from water radiolysis were scavenged, and significant inhibition of PDA degradation was observed at absorbed doses less than 1 kGy. In the presence of nitrous oxide, the generation of hydroxyl radicals (rad OH) was promoted during gamma irradiation and PDA degradation was drastically enhanced.

Supercritical fluid processing of drug nanoparticles in stable suspension.

PubMed

Pathak, Pankaj; Meziani, Mohammed J; Desai, Tarang; Foster, Charles; Diaz, Julian A; Sun, Ya-Ping

2007-07-01

Significant effort has been directed toward the development of drug formulation and delivery techniques, especially for the drug of no or poor aqueous solubility. Among various strategies to address the solubility issue, the reduction of drug particle sizes to the nanoscale has been identified as a potentially effective and broadly applicable approach. Complementary to traditional methods, supercritical fluid techniques have found unique applications in the production and processing of drug particles. Here we report the application of a newly developed supercritical fluid processing technique, Rapid Expansion of a Supercritical Solution into a Liquid Solvent, to the nanosizing of potent antiparasitic drug Amphotericin B particles. A supercritical carbon dioxide-cosolvent system was used for the solubilization and processing of the drug. The process produced well-dispersed nanoscale Amphotericin B particles suspended in an aqueous solution, and the suspension was intrinsically stable or could be further stabilized in the presence of water-soluble polymers. The properties of the drug nanoparticles were found to be dependent on the type of cosolvent used. The results on the use of dimethyl sulfoxide and methanol as cosolvents and their effects on the properties of nanosized Amphotericin B particles are presented and discussed.

Anti Microbial activity of the various leaf extracts of Vitex negundo Linn.

PubMed Central

Devi, P. Renuka; KokilaVani, R.; Poogotha, S. Gnana

2008-01-01

The antibacterial activity of the leaves of Vitex negundo was tested against three bacteria Viz., Staphylococcus aureus Escherichia coli and Klebsiella Peumoniae, The fresh aqueous, heated aqueous extract, chloroform and methanolic extract of leaves were used for screening their antibacterial potential. The fresh and aqueous extracts of leaves in various dilutions were found to have antibacterial activity against the three bacteria. PMID:22557306

Photochemistry of copper(II) complexes with macrocyclic amine ligands

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

Muralidharan, S.; Ferraudi, G.

1981-07-01

The photochemical properties of Cu(dl-Me/sub 6/(14)aneN/sub 4/)/sup 2 +/ and Cu(rac-Me/sub 6/(14)aneN/sub 4/)/sup 2 +/ in the presence and absence of axially coordinated ligands have been investigated by continuous and flash irradiations. Flash photolysis of the complexes in deaerated aqueous solutions revealed the presence of copper-ligand radical complexes with closed- and open-cycle ligands. Flash photolysis of methanolic solutions of the complexes, in the presence of halides and pseudohalides, shows Cu(III) macrocyclic intermediates. The experimental observations can be explained in terms of two primary photoprocesses with origins in distinctive charge transfer to metal states. These states have been assigned as aminomore » to copper(II) charge-transfer state and acido to copper(II) charge-transfer state.« less

Electrochemistry for biofuel generation: transformation of fatty acids and triglycerides to diesel-like olefin/ether mixtures and olefins.

PubMed

dos Santos, Tatiane R; Harnisch, Falk; Nilges, Peter; Schröder, Uwe

2015-03-01

Electroorganic synthesis can be exploited for the production of biofuels from fatty acids and triglycerides. With Coulomb efficiencies (CE) of up to 50 %, the electrochemical decarboxylation of fatty acids in methanolic and ethanolic solutions leads to the formation of diesel-like olefin/ether mixtures. Triglycerides can be directly converted in aqueous solutions by using sonoelectrochemistry, with olefins as the main products (with a CE of more than 20 %). The latter reaction, however, is terminated at around 50 % substrate conversion by the produced side-product glycerol. An energy analysis shows that the electrochemical olefin synthesis can be an energetically competitive, sustainable, and--in comparison with established processes--economically feasible alternative for the exploitation of fats and oils for biofuel production. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Adsorption of Ten Microcystin Congeners to Common Laboratory-Ware Is Solvent and Surface Dependent.

PubMed

Altaner, Stefan; Puddick, Jonathan; Wood, Susanna A; Dietrich, Daniel R

2017-04-06

Cyanobacteria can produce heptapetides called microcystins (MC) which are harmful to humans due to their ability to inhibit cellular protein phosphatases. Quantitation of these toxins can be hampered by their adsorption to common laboratory-ware during sample processing and analysis. Because of their structural diversity (>100 congeners) and different physico-chemical properties, they vary in their adsorption to surfaces. In this study, the adsorption of ten different MC congeners (encompassing non-arginated to doubly-arginated congeners) to common laboratory-ware was assessed using different solvent combinations. Sample handling steps were mimicked with glass and polypropylene pipettes and vials with increasing methanol concentrations at two pH levels, before analysis by liquid chromatography-tandem mass spectrometry. We demonstrated that MC adsorb to polypropylene surfaces irrespective of pH. After eight successive pipet actions using polypropylene tips ca. 20% of the MC were lost to the surface material, which increased to 25%-40% when solutions were acidified. The observed loss was alleviated by changing the methanol (MeOH) concentration in the final solvent. The required MeOH concentration varied depending on which congener was present. Microcystins only adsorbed to glass pipettes (loss up to 30% after eight pipet actions) when in acidified aqueous solutions. The latter appeared largely dependent on the presence of ionizable groups, such as arginine residues.

Intrinsic Conformational Preferences of Cα,α-Dibenzylglycine

PubMed Central

Casanovas, Jordi; Nussinov, Ruth; Alemán, Carlos

2009-01-01

The intrinsic conformational preferences of Cα,α-dibenzylglycine, a symmetric α,α-dialkylated amino acid bearing two benzyl substituents on the α-carbon atom, have been determined using quantum chemical calculations at the B3LYP/6-31+G(d,p) level. A total of 46 minimum energy conformations were found for the N-acetyl-N'-methylamide derivative, even though only 9 of them showed a relative energy lower than 5.0 kcal/mol. The latter involves C7, C5 and α' backbone conformations stabilized by intramolecular hydrogen bonds and/or N-H…π interactions. Calculation of the conformational free energies in different environments (gas-phase, carbon tetrachloride, chloroform, methanol and water solutions) indicates that four different minima (two C5 and two C7) are energetically accessible at room temperature in the gas-phase, while in methanol and aqueous solutions one such minimum (C5) becomes the only significant conformation. Comparison with results recently reported for Cα,α-diphenylglycine indicates that substitution of phenyl side groups by benzyl enhances the conformational flexibility leading to (i) a reduction of the strain of the peptide backbone; and (ii) alleviating the repulsive interactions between the π electron density of the phenyl groups and the lone pairs of the carbonyl oxygen atoms. PMID:18465898

Facilitated preparation of bioconjugatable zwitterionic quantum dots using dual-lipid encapsulation.

PubMed

Shrake, Robert; Demillo, Violeta G; Ahmadiantehrani, Mojtaba; Zhu, Xiaoshan; Publicover, Nelson G; Hunter, Kenneth W

2015-01-01

Zwitterionic quantum dots prepared through incorporated zwitterionic ligands on quantum dot surfaces, are being paid significant attention in biomedical applications because of their excellent colloidal stability across a wide pH and ionic strength range, antifouling surface, good biocompatibility, etc. In this work, we report a dual-lipid encapsulation approach to prepare bioconjugatable zwitterionic quantum dots using amidosulfobetaine-16 lipids, dipalmitoyl-sn-glycero-3-phosphoethanolamine lipids with functional head groups, and CuInS2/ZnS quantum dots in a tetrahydrofuran/methanol/water solvent system with sonication. Amidosulfobetaine-16 is a zwitterionic lipid and dipalmitoyl-sn-glycero-3-phosphoethanolamine, with its functional head, provides bioconjugation capability. Under sonication, tetrahydrofuran/methanol containing amidosulfobetaine-16, dipalmitoyl-sn-glycero-3-phosphoethanolamine, and hydrophobic quantum dots are dispersed in water to form droplets. Highly water-soluble tetrahydrofuran/methanol in droplets is further displaced by water, which induces the lipid self-assembling on hydrophobic surface of quantum dots and thus forms water soluble zwitterionic quantum dots. The prepared zwitterionic quantum dots maintain colloidal stability in aqueous solutions with high salinity and over a wide pH range. They are also able to be conjugated with biomolecules for bioassay with minimal nonspecific binding. Copyright © 2014 Elsevier Inc. All rights reserved.

Isotopic separation of acetaldehyde and methanol from their deuterated isotopologues on a porous layer open tubular column allows quantification by stable isotope dilution without mass spectrometric detection.

PubMed

Schmarr, Hans-Georg; Wacker, Michael; Mathes, Maximilian

2017-01-20

An isotopic separation of acetaldehyde and acetaldehyde-2,2,2-d3 was achieved in a temperature programmed run on a porous layer open tubular (PLOT) capillary column coated with particles of divinylbenzene ethylene glycol/dimethylacrylate (Rt ® -U-BOND). This is the prerequisite for the development of quantitative analytical methods based on a stable isotope dilution assay (SIDA) without a mass spectrometric detection (non-MS SIDA). For routine analysis a flame ionization detector (FID) can thus be applied as a robust and low-cost alternative. In a preliminary study, static headspace extraction and gas chromatographic separation (HS-GC-FID) of acetaldehyde in aqueous solutions was shown as an application. Good linearity was obtained in a calibration range from 0.4 to 40mgL -1 , with peak integration benefitting from the inverse isotope effect encountered on the specific porous polymer. Furthermore, separation of methanol and deuterated methanol (d3) could also be achieved under the same chromatographic conditions. The achieved isotopic separation of these important volatile compounds now allows non-MS SIDA-based methods that are still to be developed. Copyright © 2016 Elsevier B.V. All rights reserved.

Evaluation of Antioxidant, Antimicrobial, and Antiurolithiatic Potential of Different Solvent Extracts of Aerva lanata Linn Flowers

PubMed Central

Behera, Padma Charan; Ghosh, Manik

2018-01-01

Introduction: Aerva lanata (Linn) of family Amaranthaceae is an important and commonly used plant for its medicinal and pharmacological properties and proving the traditional uses of flowers of A. lanata Linn. Objective: All extracts of A. lanata were further evaluated for antioxidant, antimicrobial, and antiurolithiatic potential to scientifically prove the traditional uses. Materials and Methods: In the present investigation, different solvent extracts of flowers were obtained using a Soxhlet extractor. Microorganisms were obtained from IMTECH, Chandigarh. Antiurolithiatic study was carried out in Albino Research and Training Centre, Hyderabad. Results: Regardless of the antioxidant studied, the methanolic extract presented the highest antioxidant activity and the aqueous extracts offered the lowest, following the order: methanolic extract > ethyl acetate > chloroform > aqueous. The results of this antimicrobial study indicate that methanolic extract of A. lanata could be used as antimicrobial agents. Overall, the methanolic flower extract of A. lanata (Linn) was significantly more promising as antiurolithiatic spectrum. This result also suggested the potential usefulness of the methanolic extract as an antiurolithiatic agent. Conclusion: Henceforward, this research can be acknowledged as a prime new report that focuses on the application of A. lanata (Linn) as an antioxidant, antimicrobial, and antiurolithiatic agent. SUMMARY Overall, methanolic flower extract of Aerva lanata Linn showed promising antioxidant activityAdditionally, methanolic flower extract of A. lanata Linn exhibited remarkable antimicrobial and antiurolithiatic potential. Abbreviations used: IMTECH Chandigarh: Institute of Microbial Technology, Chandigarh; IMMT: Institute of Mineral and Material Technology; CSIR: Council of Scientific & Industrial Research; DPPH: 1,1-diphenyl-2-picrylhydrazyl; MTCC: Microbial Type Culture Collection; BHT: Butylated Hydroxyl Toluene. PMID:29576701

In Vitro Antimicrobial Potential of the Lichen Parmotrema sp. Extracts against Various Pathogens.

PubMed

Chauhan, Ritika; Abraham, Jayanthi

2013-07-01

The ongoing increasing antibiotic resistance is one of the biggest challenges faced by global public health. The perennial need for new antimicrobials against a background of increasing antibiotic resistance in pathogenic and opportunistic microorganisms obliges the scientific community to constantly develop new drugs and antimicrobial agents. Lichens are known prolific sources of natural antimicrobial drugs and biologically active natural products. This study was aimed to explore in vitro antimicrobial activity of lichen Parmotrema sp. The methanol and aqueous extracts of lichen Parmotrema sp. was extracted using Soxhlet extractor. Antibiotic assessment of methanol and aqueous extracts was done against eight bacterial (Escherichia coli, Staphylococcus aureus, Proteus mirabilis, Salmonella sp., Shigella sp., Enterococci faecalis, Pseudomonas aeruginosa, Klebsiella pneumoniae,) clinical pathogens and five plant pathogenic fungal strains (Aspergillus terreus strain JAS1, Scedosporium sp. JAS1, Ganoderma sp. JAS4, Candida tropicalis and Fusarium sp.) by Kirby-Bauer method. The methanol lichen Parmotrema sp. extract inhibited all the test organisms. The highest antibacterial activity was found against Pseudomonas aeruginosa and Staphylococcus aureus. The weakest activity was manifested in Salmonella sp. and Scedosporium sp. JAS1. Strong antifungal effect was found against Ganoderma sp. JAS4 and Fusarium sp. The aqueous lichen Parmotrema sp. extract revealed neither antibacterial nor antifungal activity. The present study shows that tested lichen Parmotrema sp. extracts demonstrated a strong antimicrobial effect. That suggests the active components from methanol extracts of the investigated lichen Parmotrema sp. can be used as natural antimicrobial agent against pathogens.

Improving the Isotretinoin Photostability by Incorporating in Microemulsion Matrix

PubMed Central

Patel, Mrunali R.; Patel, Rashmin B.; Parikh, Jolly R.; Patel, Bharat G.

2011-01-01

The present paper demonstrates the increased photostability of isotretinoin when loaded in microemulsion. The photodegradation of isotretinoin, in methanol and microemulsion formulation was studied under direct sun light. The photodegradation process was monitored by UV spectrophotometry. In methanol solution, isotretinoin undergoes complete photodegradation just within a few minutes of light exposure. Isotretinoin incorporated in microemulsion formulation showed an increased stability in comparison to the methanol solutions. In particular for isotretinoin, a residual concentration of 75% was still present after a light irradiance versus a residual value of just 16% measured at the same time in methanol solution. Further, degradation kinetic parameters of isotretinoin-loaded microemulsion formulation were demonstrated increase isotretinoin half-life about five-times in comparison with a methanol solution under a direct sun light. PMID:22389863

The application of HPLC ESI MS in the investigation of the flavonoids and flavonoid glycosides of a Caribbean Lamiaceae plant with potential for bioaccumulation.

PubMed

Peter, Sonia R; Peru, Kerry M; Fahlman, Brian; McMartin, Dena W; Headley, John V

2015-01-01

As part of an exchange technology program between the government of Barbados and Environment Canada, methanolic and aqueous extracts from the flavonoid-rich Lamiaceae family were characterized using negative-ion electrospray mass spectrometry. The species investigated is part of the Caribbean Pharmacopoeia, and is used for a variety of health issues, including colds, flu, diabetes, and hypertension. The extracts were investigated for structural elucidation of phenolics, identification of chemical taxonomic profile, and evidence of bio-accumulator potential. The methanolic and aqueous leaf extracts of Plectranthus amboinicus yielded rosmarinic acid, ladanein, cirsimaritin, and other methoxylated flavonoids. This genus also shows a tendency to form conjugates with monosaccharides, including glucose, galactose, and rhamnose. The aqueous extract yielded four isomeric rhamnosides. The formation of conjugates by Plectranthus amboinicus is thus evidence of high bioaccumulator significance.

Anti microbial activity of the various leaf extracts of Vitex negundo Linn.

PubMed Central

Devi, P. Renuka; Kokilavani, R.; Poongothai, S. Gnana

2008-01-01

The antibacterial activity of the leaves of Vitex negundo was tested against three types of bacteria Viz., Staphylococcus aureus, Escherichia coli and Klebsiella Pneumoniae. The fresh, aqueous, heated aqueous extract, chloroform and methanolic extract of leaves were used for screening their antibacterial potential. The fresh and aqueous extracts of leaves in various dilutions were found to have antibacterial activity against the three bacteria. PMID:22557282

Mechanistic and Kinetic Study of Singlet O2 Oxidation of Methionine by On-Line Electrospray Ionization Mass Spectrometry.

PubMed

Liu, Fangwei; Lu, Wenchao; Yin, Xunlong; Liu, Jianbo

2016-01-01

We report a reaction apparatus developed to monitor singlet oxygen ((1)O2) reactions in solution using on-line ESI mass spectrometry and spectroscopy measurements. (1)O2 was generated in the gas phase by the reaction of H2O2 with Cl2, detected by its emission at 1270 nm, and bubbled into aqueous solution continuously. (1)O2 concentrations in solution were linearly related to the emission intensities of airborne (1)O2, and their absolute scales were established based on a calibration using 9,10-anthracene dipropionate dianion as an (1)O2 trapping agent. Products from (1)O2 oxidation were monitored by UV-Vis absorption and positive/negative ESI mass spectra, and product structures were elucidated using collision-induced dissociation-tandem mass spectrometry. To suppress electrical discharge in negative ESI of aqueous solution, methanol was added to electrospray via in-spray solution mixing using theta-glass ESI emitters. Capitalizing on this apparatus, the reaction of (1)O2 with methionine was investigated. We have identified methionine oxidation intermediates and products at different pH, and measured reaction rate constants. (1)O2 oxidation of methionine is mediated by persulfoxide in both acidic and basic solutions. Persulfoxide continues to react with another methionine, yielding methionine sulfoxide as end-product albeit with a much lower reaction rate in basic solution. Density functional theory was used to explore reaction potential energy surfaces and establish kinetic models, with solvation effects simulated using the polarized continuum model. Combined with our previous study of gas-phase methionine ions with (1)O2, evolution of methionine oxidation pathways at different ionization states and in different media is described.

Multi-walled carbon nanotubes as solid-phase extraction sorbents for simultaneous determination of type A trichothecenes in maize, wheat and rice by ultra-high performance liquid chromatography-tandem mass spectrometry.

PubMed

Dong, Maofeng; Si, Wenshuai; Jiang, Keqiu; Nie, Dongxia; Wu, Yongjiang; Zhao, Zhihui; De Saeger, Sarah; Han, Zheng

2015-12-04

A solid-phase extraction (SPE) procedure using multi-walled carbon nanotubes (MWCNTs) as sorbents coupled with ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was developed for simultaneous determination of four type A trichothecenes in maize, wheat and rice for the first time. Several key parameters including the composition of sample loading solutions, washing and elution solvents were thoroughly investigated to achieve optimal SPE recoveries and efficiency. Performance of the MWCNTs materials was significantly affected by pH, and after optimization, n-hexane and 5% methanol aqueous solution as the washing solutions and methanol containing 1% formic acid as the elution solvent presented an excellent purification efficiency for the four targets in the different matrices. The method was validated by determining the linearity (R(2)≥0.992), recovery (73.4-113.7%), precision (1.2-17.1%) and sensitivity (limit of quantification in the range of 0.02-0.10μg/kg), and was further applied for simultaneous determination of type A trichothecenes in 30 samples. Although low contamination levels of type A trichothecenes in wheat, maize and rice were observed revealing mitigated risks to consumers in Shanghai, China, the developed method has proven to be a valuable tool for type A trichothecenes monitoring in complex crop matrices. Copyright © 2015 Elsevier B.V. All rights reserved.

Direct methanol fuel cell and system

DOEpatents

Wilson, Mahlon S.

2004-10-26

A fuel cell having an anode and a cathode and a polymer electrolyte membrane located between anode and cathode gas diffusion backings uses a methanol vapor fuel supply. A permeable polymer electrolyte membrane having a permeability effective to sustain a carbon dioxide flux equivalent to at least 10 mA/cm.sup.2 provides for removal of carbon dioxide produced at the anode by reaction of methanol with water. Another aspect of the present invention includes a superabsorpent polymer material placed in proximity to the anode gas diffusion backing to hold liquid methanol or liquid methanol solution without wetting the anode gas diffusion backing so that methanol vapor from the liquid methanol or liquid methanol-water solution is supplied to the membrane.

Dispersive liquid-liquid microextraction based on solidification of floating organic droplet for the determination of triazine and triazoles in mineral water samples.

PubMed

Bolzan, Cátia M; Caldas, Sergiane S; Guimarães, Bruno S; Primel, Ednei G

2016-09-01

A simple, rapid, and sensitive method for the determination of atrazine, simazine, cyproconazole, tebuconazole, and epoxiconazole in mineral water employing the dispersive liquid-liquid microextraction with solidification of a floating organic drop with determination by liquid chromatography tandem mass spectrometry has been developed. A mixed solution of 250 μL 1-dodecanol and 1250 μL methanol was injected rapidly into 10 mL aqueous solution (pH 7.0) with 2% w/v NaCl. After centrifugation for 5 min at 2000 rpm, the organic solvent droplets floated on the surface of the aqueous solution and the floating solvent solidified. The method limits of detection were between 3.75 and 37.5 ng/L and limits of quantification were between 12.5 and 125 ng/L. The recoveries ranged from 70 to 118% for repeatability and between 76 and 95% for intermediate precision with a relative standard deviation from 2 to 18% for all compounds. Low matrix effect was observed. The proposed method can be successfully applied in routine analysis for determination of pesticide residues in mineral water samples, allowing for monitoring of triazine and triazoles at levels below the regulatory limits set by international and national legislations. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Neutral glycoconjugated amide-based calix[4]arenes: complexation of alkali metal cations in water.

PubMed

Cindro, Nikola; Požar, Josip; Barišić, Dajana; Bregović, Nikola; Pičuljan, Katarina; Tomaš, Renato; Frkanec, Leo; Tomišić, Vladislav

2018-02-07

Cation complexation in water presents a unique challenge in calixarene chemistry, mostly due to the fact that a vast majority of calixarene-based cation receptors is not soluble in water or their solubility has been achieved by introducing functionalities capable of (de)protonation. Such an approach inevitably involves the presence of counterions which compete with target cations for the calixarene binding site, and also rather often requires the use of ion-containing buffer solutions in order to control the pH. Herein we devised a new strategy towards the solution of this problem, based on introducing carbohydrate units at the lower or upper rim of calix[4]arenes which comprise efficient cation binding sites. In this context, we prepared neutral, water-soluble receptors with secondary or tertiary amide coordinating groups, and studied their complexation with alkali metal cations in aqueous and methanol (for the comparison purpose) solutions. Complexation thermodynamics was quantitatively characterized by UV spectrometry and isothermal titration calorimetry, revealing that one of the prepared tertiary amide derivatives is capable of remarkably efficient (log K ≈ 5) and selective binding of sodium cations among alkali metal cations in water. Given the ease of the synthetic procedure used, and thus the variety of accessible analogues, this study can serve as a platform for the development of reagents for diverse purposes in aqueous media.

Preparation and Cross-Linking of All-Acrylamide Diblock Copolymer Nano-Objects via Polymerization-Induced Self-Assembly in Aqueous Solution

PubMed Central

2017-01-01

Various carboxylic acid-functionalized poly(N,N-dimethylacrylamide) (PDMAC) macromolecular chain transfer agents (macro-CTAs) were chain-extended with diacetone acrylamide (DAAM) by reversible addition–fragmentation chain transfer (RAFT) aqueous dispersion polymerization at 70 °C and 20% w/w solids to produce a series of PDMAC–PDAAM diblock copolymer nano-objects via polymerization-induced self-assembly (PISA). TEM studies indicate that a PDMAC macro-CTA with a mean degree of polymerization (DP) of 68 or higher results in the formation of well-defined spherical nanoparticles with mean diameters ranging from 40 to 150 nm. In contrast, either highly anisotropic worms or polydisperse vesicles are formed when relatively short macro-CTAs (DP = 40–58) are used. A phase diagram was constructed to enable accurate targeting of pure copolymer morphologies. Dynamic light scattering (DLS) and aqueous electrophoresis studies indicated that in most cases these PDMAC–PDAAM nano-objects are surprisingly resistant to changes in either solution pH or temperature. However, PDMAC40–PDAAM99 worms do undergo partial dissociation to form a mixture of relatively short worms and spheres on adjusting the solution pH from pH 2–3 to around pH 9 at 20 °C. Moreover, a change in copolymer morphology from worms to a mixture of short worms and vesicles was observed by DLS and TEM on heating this worm dispersion to 50 °C. Postpolymerization cross-linking of concentrated aqueous dispersions of PDMAC–PDAAM spheres, worms, or vesicles was performed at ambient temperature using adipic acid dihydrazide (ADH), which reacts with the hydrophobic ketone-functionalized PDAAM chains. The formation of hydrazone groups was monitored by FT-IR spectroscopy and afforded covalently stabilized nano-objects that remained intact on exposure to methanol, which is a good solvent for both blocks. Rheological studies indicated that the cross-linked worms formed a stronger gel compared to linear precursor worms. PMID:28260814

Symmetric and asymmetric squarylium dyes as noncovalent protein labels: a study by fluorimetry and capillary electrophoresis.

PubMed

Welder, Frank; Paul, Beverly; Nakazumi, Hiroyuki; Yagi, Shigeyuki; Colyer, Christa L

2003-08-05

Noncovalent interactions between two squarylium dyes and various model proteins have been explored. NN127 and SQ-3 are symmetric and asymmetric squarylium dyes, respectively, the fluorescence emissions of which have been shown to be enhanced upon complexation with proteins such as bovine serum albumin (BSA), human serum albumin (HSA), beta-lactoglobulin A, and trypsinogen. Although these dyes are poorly soluble in aqueous solution, they can be dissolved first in methanol followed by dilution with aqueous buffer without precipitation, and are then suitable for use as fluorescent labels in protein determination studies. The nature of interactions between these dyes and proteins was studied using a variety of buffer systems, and it was found that electrostatic interactions are involved but not dominant. Dye/protein stoichiometries in the noncovalent complexes were found to be 1:1 for SQ-3, although various possible stoichiometries were found for NN127 depending upon pH and protein. Association constants on the order of 10(5) and 10(7) were found for noncovalent complexes of SQ-3 and NN127, respectively, with HSA, indicating stronger interactions of the symmetric dye with proteins. Finally, HSA complexes with NN127 were determined by capillary electrophoresis with laser-induced fluorescence detection (CE-LIF). In particular, NN127 shows promise as a reagent capable of fluorescently labeling analyte proteins for analysis by CE-LIF without itself being significantly fluorescent under the aqueous solution conditions studied herein.

Gel spinning of silk tubes for tissue engineering

PubMed Central

Lovett, Michael; Cannizzaro, Christopher; Vunjak-Novakovic, Gordana; Kaplan, David L.

2011-01-01

Tubular vessels for tissue engineering are typically fabricated using a molding, dipping, or electrospinning technique. While these techniques provide some control over inner and outer diameters of the tube, they lack the ability to align the polymers or fibers of interest throughout the tube. This is an important aspect of biomaterial composite structure and function for mechanical and biological impact of tissue outcomes. We present a novel aqueous process system to spin tubes from biopolymers and proteins such as silk fibroin. Using silk as an example, this method of winding an aqueous solution around a reciprocating rotating mandrel offers substantial improvement in the control of the tube properties, specifically with regard to winding pattern, tube porosity, and composite features. Silk tube properties are further controlled via different post-spinning processing mechanisms such as methanol-treatment, air-drying, and lyophilization. This approach to tubular scaffold manufacture offers numerous tissue engineering applications such as complex composite biomaterial matrices, blood vessel grafts and nerve guides, among others. PMID:18801570

Zn x Cd1-x S tunable band structure-directing photocatalytic activity and selectivity of visible-light reduction of CO2 into liquid solar fuels

NASA Astrophysics Data System (ADS)

Tang, Lanqin; Kuai, Libang; Li, Yichang; Li, Haijin; Zhou, Yong; Zou, Zhigang

2018-02-01

A series of Zn x Cd1-x S monodispersed nanospheres were successfully synthesized with tunable band structures. As-prepared Zn x Cd1-x S solid solutions show much enhanced photocatalytic efficiency for CO2 photoreduction in aqueous solutions under visible light irradiation, relative to pure CdS analog. Methanol (CH3OH) and acetaldehyde (CH3CHO) are the major products of CO2 photoreduction for the solid solutions with x = 0, 0.2, and 0.5. Interestingly, Zn0.8Cd0.2S photocatalyst with a wide band gap can also additionally generate ethanol (CH3CH2OH) besides CH3OH and CH3CHO. The balance between the band structure-directing redox capacity and light absorption should be considered to influence both product yield and selectivity of CO2 photoreduction. The possible photoreduction mechanism was tentatively proposed.

Antimicrobial Activity and Brine Shrimp Lethality Bioassay of the Leaves Extract of Dillenia indica Linn

PubMed Central

Apu, AS; Muhit, MA; Tareq, SM; Pathan, AH; Jamaluddin, ATM; Ahmed, M

2010-01-01

The crude methanolic extract of Dillenia indica Linn. (Dilleniaceae) leaves has been investigated for the evaluation of antimicrobial and cytotoxic activities. Organic solvent (n-hexane, carbon tetrachloride and chloroform) fractions of methanolic extract and methanolic fraction (aqueous) were screened for their antimicrobial activity by disc diffusion method. Besides, the fractions were screened for cytotoxic activity using brine shrimp (Artemia salina) lethality bioassay. Among the four fractions tested, n-hexane, carbon tetrachloride, and chloroform fractions showed moderate antibacterial and antifungal activity compared to standard antibiotic, kanamycin. The average zone of inhibition was ranged from 6 to 8 mm at a concentration of 400 µg/disc. But the aqueous fraction was found to be insensitive to microbial growth. Compared to vincristine sulfate (with LC50 of 0.52 µg/ ml), n-hexane and chloroform fractions demonstrated a significant cytotoxic activity (having LC50 of 1.94 µg/ml and 2.13 µg/ml, respectively). The LC50 values of the carbon tetrachloride and aqueous fraction were 4.46 µg/ml and 5.13 µg/ ml, respectively. The study confirms the moderate antimicrobial and potent cytotoxic activities of Dillenia indica leaves extract and therefore demands the isolation of active principles and thorough bioassay. PMID:21331191

Decoupling the Effects of High Crystallinity and Surface Area on the Photocatalytic Overall Water Splitting over β-Ga2 O3 Nanoparticles by Chemical Vapor Synthesis.

PubMed

Lukic, Sasa; Menze, Jasper; Weide, Philipp; Busser, G Wilma; Winterer, Markus; Muhler, Martin

2017-09-11

Chemical vapor synthesis (CVS) is a unique method to prepare well-defined photocatalyst materials with both large specific surface area and a high degree of crystallinity. The obtained β-Ga 2 O 3 nanoparticles were optimized for photocatalysis by reductive photodeposition of the Rh/CrO x co-catalyst system. The influence of the degree of crystallinity and the specific surface area on photocatalytic aqueous methanol reforming and overall water splitting (OWS) was investigated by synthesizing β-Ga 2 O 3 samples in the temperature range from 1000 °C to 1500 °C. With increasing temperature, the specific surface area and the microstrain were found to decrease, whereas the degree of crystallinity and the crystallite size increased. Whereas the photocatalyst with the highest specific surface area showed the highest aqueous methanol reforming activity, the highest OWS activity was that for the sample with an optimum ratio between high degree of crystallinity and specific surface area. Thus, it was possible to show that the facile aqueous methanol reforming and the demanding OWS have different requirements for high photocatalytic activity. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

The in vitro biological activity of Lepidium meyenii extracts.

PubMed

Valentová, K; Buckiová, D; Kren, V; Peknicová, J; Ulrichová, J; Simánek, V

2006-03-01

The biological activity of methanolic and aqueous extracts from dehydrated hypocotyls of Lepidium meyenii (Brassicaceae, vernacular name "maca"), was studied on rat hepatocytes and human breast cancer MCF-7 cells. The extracts did not exhibit cytotoxicity in hepatocyte primary cultures up to 10 mg/ml as measured by the MTT viability test, and lactate dehydrogenase (LDH) and aspartate aminotransferase (AST) leakage. Moreover, after 72 h, extracts inhibited LDH and AST leakage from the hepatocytes. When hepatocytes were intoxicated by t-butyl hydroperoxide, neither extract prevented oxidative damage. Both extracts showed weak antioxidant activity in the DPPH radical scavenging test with IC(50) values of 3.46 +/- 0.16 and 0.71 +/- 0.10 mg/ml, for aqueous and methanolic extracts, respectively. Thus, the observed effect on spontaneous enzyme leakage is probably mediated through mechanisms other than antioxidant activity. Both methanolic and aqueous extracts have shown estrogenic activity comparable with that of silymarin in MCF-7 cell line. Maca estrogenicity was exhibited in the range from 100 to 200 mug of extract per ml. The findings in the present study show that maca does not display in vitro hepatotoxicity. In contrast, a slight cytoprotective effect, probably not mediated by antioxidant capacity, was noted. Maca extracts exhibited estrogenic activity comparably to the effect of silymarin in MCF-7 cells.

Suaveolic Acid: A Potent Phytotoxic Substance of Hyptis suaveolens

PubMed Central

Islam, A. K. M. Mominul; Ohno, Osamu; Suenaga, Kiyotake; Kato-Noguchi, Hisashi

2014-01-01

Hyptis suaveolens (Lamiaceae) is an exotic invasive plant in many countries. Earlier studies reported that the aqueous, methanol, and aqueous methanol extract of H. suaveolens and its residues have phytotoxic properties. However, to date, the phytotoxic substances of this plant have not been reported. Therefore, the objectives of this study were isolation and identification of phytotoxic substances of H. suaveolens. Aqueous methanol extract of this plant was purified by several chromatographic runs through bioassay guided fractionation using garden cress (Lepidium sativum) as a test plant. Final purification of a phytotoxic substance was achieved by reverse phase HPLC and characterized as 14α-hydroxy-13β-abiet-8-en-18-oic acid (suaveolic acid) by high-resolution ESI-MS, 1H-,13C-NMR, CD, and specific rotation. Suaveolic acid inhibited the shoot growth of garden cress, lettuce (Lactuca sativa), Italian ryegrass (Lolium multiflorum), and barnyard grass (Echinochloa crus-galli) at concentrations greater than 30 µM. Root growth of all but lettuce was also inhibited at concentrations greater than 30 µM. The inhibitory activities were concentration dependent. Concentrations required for 50% growth inhibition of suaveolic acid for those test plant species were ranged from 76 to 1155 µM. Therefore, suaveolic acid is phytotoxic and may be responsible for the phytotoxicity of H. suaveolens plant extracts. PMID:25405221

Comparative evaluation of different extracts of leaves of Psidium guajava Linn. for hepatoprotective activity.

PubMed

Roy, Chanchal K; Das, Amit Kumar

2010-01-01

The study was designed to evaluate the hepatoprotective activity of different extracts (petroleum ether, chloroform, ethyl acetate, methanol and aqueous) of P. guajava in acute experimental liver injury induced by carbon tetrachloride and paracetamol. The effects observed were compared with a known hepatoprotective agent, silymarin (100 mg/kg p.o.). In the acute liver damage induced by different hepatotoxins, P. guajava methanolic leaf extract (200 mg/kg, p.o.) significantly reduced the elevated serum levels of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase and bilirubin in carbon tetrachloride and paracetamol induced hepatotoxicity. P. guajava ethyl acetate leaf extract (200 mg/kg, p.o.) significantly reduced the elevated serum levels of aspartate aminotransferase, alanine aminotransferase and bilirubin in carbon tetrachloride induced hepatotoxicity whereas P. guajava aqueous leaf extract (200 mg/kg, p.o.) significantly reduced the elevated serum levels of alkaline phosphatase, alanine aminotransferase and bilirubin in carbon tetrachloride induced hepatotoxicity. P. guajava ethyl acetate and aqueous leaf extracts (200 mg/kg, p.o.) significantly reduced the elevated serum levels of aspartate aminotransferase in paracetamol induced hepatotoxicity. Histological examination of the liver tissues supported the hepatoprotection. It is concluded that the methanolic extract of leaves of Psidium guajava plant possesses better hepatoprotective activity compared to other extracts.

Self-spinning nanoparticle laden microdroplets for sensing and energy harvesting

NASA Astrophysics Data System (ADS)

Bhattacharjee, Mitradip; Pasumarthi, Viswanath; Chaudhuri, Joydip; Singh, Amit Kumar; Nemade, Harshal; Bandyopadhyay, Dipankar

2016-03-01

Exposure of a volatile organic vapour could set in powerful rotational motion a microdroplet composed of an aqueous salt solution loaded with metal nanoparticles. The solutal Marangoni motion on the surface originating from the sharp difference in the surface tension of water and organic vapour stimulated the strong vortices inside the droplet. The vapour sources of methanol, ethanol, diethyl ether, toluene, and chloroform stimulated motions of different magnitudes could easily be correlated to the surface tension gradient on the drop surface. Interestingly, when the nanoparticle laden droplet of aqueous salt solution was connected to an external electric circuit through a pair of electrodes, an ~85-95% reduction in the electrical resistance was observed across the spinning droplet. The extent of reduction in the resistance was found to have a correlation with the difference in the surface tension of the vapour source and the water droplet, which could be employed to distinguish the vapour sources. Remarkably, the power density of the same prototype was estimated to be around 7 μW cm-2, which indicated the potential of the phenomenon in converting surface energy into electrical in a non-destructive manner and under ambient conditions. Theoretical analysis uncovered that the difference in the ζ-potential near the electrodes was the major reason for the voltage generation. The prototype could also detect the repeated exposure and withdrawal of vapour sources, which helped in the development of a proof-of-concept detector to sense alcohol issuing out of the human breathing system.Exposure of a volatile organic vapour could set in powerful rotational motion a microdroplet composed of an aqueous salt solution loaded with metal nanoparticles. The solutal Marangoni motion on the surface originating from the sharp difference in the surface tension of water and organic vapour stimulated the strong vortices inside the droplet. The vapour sources of methanol, ethanol, diethyl ether, toluene, and chloroform stimulated motions of different magnitudes could easily be correlated to the surface tension gradient on the drop surface. Interestingly, when the nanoparticle laden droplet of aqueous salt solution was connected to an external electric circuit through a pair of electrodes, an ~85-95% reduction in the electrical resistance was observed across the spinning droplet. The extent of reduction in the resistance was found to have a correlation with the difference in the surface tension of the vapour source and the water droplet, which could be employed to distinguish the vapour sources. Remarkably, the power density of the same prototype was estimated to be around 7 μW cm-2, which indicated the potential of the phenomenon in converting surface energy into electrical in a non-destructive manner and under ambient conditions. Theoretical analysis uncovered that the difference in the ζ-potential near the electrodes was the major reason for the voltage generation. The prototype could also detect the repeated exposure and withdrawal of vapour sources, which helped in the development of a proof-of-concept detector to sense alcohol issuing out of the human breathing system. Electronic supplementary information (ESI) available: Discussion of simulation with results, characterization and movies of particle motion inside droplets along with detailed explanation. See DOI: 10.1039/c6nr00217j

Modeling methanol transfer in the mesoporous catalyst for the methanol-to-olefins reaction by the time-fractional diffusion equation

NASA Astrophysics Data System (ADS)

Zhokh, Alexey A.; Strizhak, Peter E.

2018-04-01

The solutions of the time-fractional diffusion equation for the short and long times are obtained via an application of the asymptotic Green's functions. The derived solutions are applied to analysis of the methanol mass transfer through H-ZSM-5/alumina catalyst grain. It is demonstrated that the methanol transport in the catalysts pores may be described by the obtained solutions in a fairly good manner. The measured fractional exponent is equal to 1.20 ± 0.02 and reveals the super-diffusive regime of the methanol mass transfer. The presence of the anomalous transport may be caused by geometrical restrictions and the adsorption process on the internal surface of the catalyst grain's pores.

The benzil-cyanide reaction and its application to the development of a selective cyanide anion indicator.

PubMed

Cho, Dong-Gyu; Kim, Jong Hoon; Sessler, Jonathan L

2008-09-10

The benzil-cyanide reaction is a cyanide-specific reaction that has been exploited to produce a colorimetric indicator for this toxic anion. This was done by producing a pi-extended analogue of benzil, 7, which is soluble in a 70:30 (v/v) mixture of methanol-water. In this medium, dilute solutions of 7 are yellow but produce colorless products when exposed to low concentrations of cyanide anion (> or = 1.7 microM; added as an aqueous NaCN solution), but no other common anions (e.g., OH(-), F(-), N3(-), benzoate(-), and H2PO4(-)). On the basis of these observations and supporting mechanistic analyses, it is concluded that the modified benzil system 7 is a promising cyanide anion indicator that is attractive in terms of its selectivity, ease-of-use, water compatibility, and the low, naked-eye discernible cyanide detection limit it provides.

Phytochemical analysis and a study on the antiestrogenic antifertility effect of leaves of Piper betel in female albino rat

PubMed Central

Biswal, Sasmita

2014-01-01

Objective: To study the effect of graded doses of the aqueous and methanolic extract of the leaves of Piper betel (PB) Linn (PBL) on the estrous cycle of female albino rats. Materials and Methods: Both the extracts were tested for their effect on the estrous cycle at three dose levels of 500, 1000 and 1500 mg/kg/day and the vaginal smears were examined daily microscopically for the different phases of the estrous cycle for a period of 30 days. Result: The estrous cycle was irregular and prolonged in the treated groups indicating anestrus condition, which would result in infertility. Both types of the extract showed a significant decrease in the duration of proestrus and estrus with a prolonged diestrus at 1000 mg/kg/day and 1500 mg/kg/day doses as compared with control. However, no change was seen in the metestrus phase. The rats treated with PB showed a significant (P < 0.05), dose-dependent decrease in the estrus phase, in comparison to the control group, the effect was more with the methanolic extract. Large, cornified cells appeared after proestrus phase with decreased number of cornified cells. There was a significant reduction in the number of the estrous cycle, in the PBL treated group. Anestrus phase appeared in all the rats treated with the aqueous and methanolic PB extract, which was not observed in the control group. However, the aqueous extract at a dose of 500 mg/kg/day had no effect either on the estrous cycle or on its different phases. The observed effect of PB leaves could be due to the flavonoids and saponin contents, which also contributes to its antiestrogenic mechanism of action. Conclusion: Both the aqueous and methanolic extract of PBL possesses antifertility effect in female albino rats. PMID:25737606

[Separation and identification of 5 glycosidic flavor precursors in tobacco by ultra performance liquid chromatography-electrospray ionization tandem mass spectrometry].

PubMed

Wu, Xinhua; Zhu, Ruizhi; Ren, Zhuoying; Wang, Kai; Mou, Dingrong; Wei, Wanzhi; Miao, Mingming

2009-11-01

A qualitative method for the identification of 5 main glycosidic flavor precursors in tobacco was developed by using ultra performance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC-ESI MS/MS) and gas chromatography-mass spectrometry (GC-MS). The glycosidic flavor precursors in tobacco were extracted with methanol, cleaned up with an XAD-2 column. The aglycones were later released by enzyme-mediated hydrolysis under the condition of pH 5. The 5 volatile aglycone moieties were identified by GC-MS standard spectra library. The precursor ions of glycosides were determined by using electrospray ionization mass spectrometry in negative ion mode, then the 5 glycosidic flavor precursors were identified by using product ion scan (MS2) finally, using UPLC-ESI MS/MS, separation and identification of 5 glycosidic flavor precursors were accomplished on an RP-C,8 column in the multiple reaction monitoring (MRM) mode by using methanol and acetic acid-ammonium acetate aqueous solution as eluent. This work lays a foundation for the analysis of glycosidic flavor precursors without the standards by using liquid chromatography-mass spectrometry.

Antioxidant activities of ficus glomerata (moraceae) leaf gall extracts

PubMed Central

Eshwarappa, Ravi Shankara Birur; Iyer, Shanthi; Subaramaihha, Sundara Rajan; Richard, S Austin; Dhananjaya, Bhadrapura Lakkappa

2015-01-01

An excess production or decreased scavenging of reactive oxygen species (ROS) has been implicated in the pathogenesis of diverse metabolic disorders such as diabetes, cancer, atherosclerosis and neurodegeneration. Hence the antioxidant therapy has gained an utmost importance in the treatment of such diseases linked to free radicals. The medicinal properties of plants have been investigated and explored for their potent antioxidant activities to counteract metabolic disorders. This research highlights the chemical composition and antioxidant potential of leaf gall extracts (aqueous and methanol) of Ficus glomerata (F. glomerata), which is extensively used in the preparation of traditional medications to treat various metabolic diseases. The presences of phenolics, flavonoids, phytosterols, terpenoids and reducing sugars were identified in both the extracts. In comparison to the aqueous extract, the methanol extract had the highest total phenolic and flavonoid content at 370 ± 3.2 mg of gallic acid equivalent per gram of dry weight (mg GAE/g dw) and 155 ± 3.2 mg of quercetin equivalent per gram of dry weight (mg QUE/g dw), respectively. The antioxidant activities of leaf gall extracts were examined using diphenylpicrylhydrazyl (DPPH), Nitric oxide scavenging, hydroxyl scavenging and ferric reducing power (FRAP) methods. In all the methods, the methanolic extract showed higher antioxidant potential than the aqueous extract. A higher content of both total phenolics and flavonoids were found in the methanolic extract and the significantly high antioxidant activity can be positively correlated to the high content of total polyphenols/flavonoids of the methanol extract. The results of this study confirm the folklore use of F. glomerata leaf gall extracts as a natural antioxidant and justify its ethnobotanical use. Further, the results of antioxidant properties encourage the use of F. glomerata leaf gall extracts for medicinal health, functional food and nutraceuticals applications. Future work will be interesting in knowing the chemical composition and better understand the mechanism of action of the antioxidants present for development as drug for its therapeutic application. PMID:25598645

Radiation graft modification of EPDM rubber

NASA Astrophysics Data System (ADS)

Katbab, A. A.; Burford, R. P.; Garnett, J. L.

N-Vinyl pyrrolidone (NVP), 2-hydroxyethylmethacrylate (HEMA) and acrylamide (AAm) have been grafted to the surface of rubber vulcanizates based on ethylene-propylene-terpolymer (EPDM) using the simultaneous radiation method to alter surface properties such as wettability and therefore biocompatibility. The effect of monomer concentration, solvent and EPDM structural factors on the grafting behavior have been investigated. The inhibitory effect upon homopolymerization of various salts has also been evaluated for the three monomers. NVP and HEMA could be grafted onto EPDM rubber in the presence of aqueous solutions of cupric nitrate at 0.005 M and 1.0 M concentrations respectively. Aqueous solutions of Mohr's salt (ammonium ferrous sulphate) at 0.05 M not only suppressed the homopolymerization of AAm but also increased grafting yield. The percentage grafting also increased with increasing AAm concentration. A mechanism has been proposed to explain the behaviour of these monomers. The inclusion of multifunctional acrylates in additive amounts (1.0 vol%) enhanced the graft degree. Modified samples were able to be efficiently stained, allowing the depth of the graft copolymerization to be determined by light microscopy. Water was found to have an accelerating effect on the polymerization of these monomers, but methanol prevented their polymerization completely. The effect of EPDM structural factors upon degree of grafting was found to vary, depending upon the monomer type.

Facile synthesis, cytotoxicity and bioimaging of Fe(3+) selective fluorescent chemosensor.

PubMed

Saleem, Muhammad; Abdullah, Razack; Ali, Anser; Park, Bong Joo; Choi, Eun Ha; Hong, In Seok; Lee, Ki Hwan

2014-04-01

The designing and development of fluorescent chemosensors have recently been intensively explored for sensitive and specific detection of environmentally and biologically relevant metal ions in aqueous solution and living cells. Herein, we report the photophysical results of alanine substituted rhodamine B derivative 3 having specific binding affinity toward Fe(3+) with micro molar concentration level. Through fluorescence titration at 599nm, we were confirmed that ligand 3 exhibited ratiometric fluorescence response with remarkable enhancement in emission intensity by complexation between 3 and Fe(3+) while it appeared no emission in case of the competitive ions (Sc(3+), Yb(3+), In(3+), Ce(3+), Sm(3+), Cr(3+), Sn(2+), Pb(2+), Ni(2+), Co(2+), Cu(2+), Ba(2+), Ca(2+), Mg(2+), Ag(+), Cs(+), Cu(+), K(+)) in aqueous/methanol (60:40, v/v) at neutral pH. However, the fluorescence as well as colorimetric response of ligand-iron complex solution was quenched by addition of KCN which snatches the Fe(3+) from complex and turn off the sensor confirming the recognition process was reversible. Furthermore, bioimaging studies against L-929 cells (mouse fibroblast cells) and BHK-21 (hamster kidney fibroblast), through confocal fluorescence microscopic experiment indicated that ligand showed good permeability and minimum toxicity against the tested cell lines. Copyright © 2014 Elsevier Ltd. All rights reserved.

The validity of the potential model in predicting the structural, dynamical, thermodynamic properties of the unary and binary mixture of water-alcohol: Methanol-water case

NASA Astrophysics Data System (ADS)

Obeidat, Abdalla; Abu-Ghazleh, Hind

2018-06-01

Two intermolecular potential models of methanol (TraPPE-UA and OPLS-AA) have been used in order to examine their validity in reproducing the selected structural, dynamical, and thermodynamic properties in the unary and binary systems. These two models are combined with two water models (SPC/E and TIP4P). The temperature dependence of density, surface tension, diffusion and structural properties for the unary system has been computed over specific range of temperatures (200-300K). The very good performance of the TraPPE-UA potential model in predicting surface tension, diffusion, structure, and density of the unary system led us to examine its accuracy and performance in its aqueous solution. In the binary system the same properties were examined, using different mole fractions of methanol. The TraPPE-UA model combined with TIP4P-water shows a very good agreement with the experimental results for density and surface tension properties; whereas the OPLS-AA combined with SPCE-water shows a very agreement with experimental results regarding the diffusion coefficients. Two different approaches have been used in calculating the diffusion coefficient in the mixture, namely the Einstein equation (EE) and Green-Kubo (GK) method. Our results show the advantageous of applying GK over EE in reproducing the experimental results and in saving computer time.

Preparation of high-aspect-ratio ZnO nanorod arrays for the detection of several organic solvents at room working temperature

NASA Astrophysics Data System (ADS)

Lee, Yi-Mu; Zheng, Min-Ren

2013-11-01

Chemical sensors based on ZnO nanorod arrays were prepared using chemical bath deposition (CBD) to investigate the sensing performance for the detection of several organic solvents with low concentrations (0.1%, 0.5%, 1%, v/v) at room temperature. High quality and high aspect-ratio (value ˜28) ZnO nanorods have a diameter of about 74 nm and average length of 2.1 μm. Nyquist plots and Bode plots of the ZnO sensors under different organic solvents were obtained by electrical impedance spectroscopy (EIS). The sensing properties such as charge-transfer resistance, double-layer capacitance and dielectric parameters were determined from the impedance spectra to explore the charge transport in low-concentration aqueous solutions. The decreasing trend of the charge-transfer resistance (Rct) as decreasing solvent concentrations is observed, and a straight line at low frequency regime indicates adsorption of water molecules on the oxide surface. The sensitivity of the ZnO sensors was calculated from the resistance variation in target solvents and in deionized water. We demonstrated the use of ZnO nanorod arrays as a chemical sensor capable of generating a different response upon exposure to methanol, ethanol, isopropyl alcohol, acetone and water, wherein the methanol sensing exhibited highest sensitivity. In addition, the ZnO sensor also demonstrates good stability and reproducibility for detection of methanol and ethanol.

Simultaneous determination of isochamaejasmin, neochamaejasmin A and aphnoretinin rat plasma by UPLC-MS/MS and its application to a pharmacokinetic study of Stellera chamaejasme L. extract.

PubMed

Wang, Ludi; Yang, Wei; Wu, Siyang; Wang, Shuyao; Kang, Chen; Ma, Xiaoli; Li, Yingfei; Li, Chuan

2018-05-01

Isochamaejasmin, neochamaejasmin A and daphnoretin derived from Stellera chamaejasme L. are important because of their reported anticancer properties. In this study, a sensitive UPLC-MS/MS method for the determination of isochamaejasmin, neochamaejasmin A and daphnoretin in rat plasma was developed. The analyte and IS were separated on an Acquity UPLC HSS T3 column (100 × 2.1 mm, 1.8 μm) using gradient elution with the mobile phase of aqueous solution (methanol-water, 1:99, v/v, containing 1 mm formic acid) and organic solution (methanol-water, 99:1, v/v, containing 1 mm formic acid) at a flow rate of 0.3 mL/min. Multiple reaction monitoring mode with negative electrospray ionization interface was carried out to detect the components. The method was validated in terms of specificity, linearity, accuracy, precision, stability, etc. Excellent linear behavior was observed over the certain concentration ranges with the correlation coefficient values >0.99. Intra- and inter-day precisions (RSD) were <6.7% and accuracy (RE) ranged from -7.0 to 12.0%. The validated method was successfully applied to investigate the pharmacokinetics of three chemical ingredients after oral administration of S. chamaejasme L. extract to rats. Copyright © 2017 John Wiley & Sons, Ltd.

Adsorption of Ten Microcystin Congeners to Common Laboratory-Ware Is Solvent and Surface Dependent

PubMed Central

Altaner, Stefan; Puddick, Jonathan; Wood, Susanna A.; Dietrich, Daniel R.

2017-01-01

Cyanobacteria can produce heptapetides called microcystins (MC) which are harmful to humans due to their ability to inhibit cellular protein phosphatases. Quantitation of these toxins can be hampered by their adsorption to common laboratory-ware during sample processing and analysis. Because of their structural diversity (>100 congeners) and different physico-chemical properties, they vary in their adsorption to surfaces. In this study, the adsorption of ten different MC congeners (encompassing non-arginated to doubly-arginated congeners) to common laboratory-ware was assessed using different solvent combinations. Sample handling steps were mimicked with glass and polypropylene pipettes and vials with increasing methanol concentrations at two pH levels, before analysis by liquid chromatography-tandem mass spectrometry. We demonstrated that MC adsorb to polypropylene surfaces irrespective of pH. After eight successive pipet actions using polypropylene tips ca. 20% of the MC were lost to the surface material, which increased to 25%–40% when solutions were acidified. The observed loss was alleviated by changing the methanol (MeOH) concentration in the final solvent. The required MeOH concentration varied depending on which congener was present. Microcystins only adsorbed to glass pipettes (loss up to 30% after eight pipet actions) when in acidified aqueous solutions. The latter appeared largely dependent on the presence of ionizable groups, such as arginine residues. PMID:28383495

Performance of the SMD and SM8 models for predicting solvation free energy of neutral solutes in methanol, dimethyl sulfoxide and acetonitrile.

PubMed

Zanith, Caroline C; Pliego, Josefredo R

2015-03-01

The continuum solvation models SMD and SM8 were developed using 2,346 solvation free energy values for 318 neutral molecules in 91 solvents as reference. However, no solvation data of neutral solutes in methanol was used in the parametrization, while only few solvation free energy values of solutes in dimethyl sulfoxide and acetonitrile were used. In this report, we have tested the performance of the models for these important solvents. Taking data from literature, we have generated solvation free energy, enthalpy and entropy values for 37 solutes in methanol, 21 solutes in dimethyl sulfoxide and 19 solutes in acetonitrile. Both SMD and SM8 models have presented a good performance in methanol and acetonitrile, with mean unsigned error equal or less than 0.66 and 0.55 kcal mol(-1) in methanol and acetonitrile, respectively. However, the correlation is worse in dimethyl sulfoxide, where the SMD and SM8 methods present mean unsigned error of 1.02 and 0.95 kcal mol(-1), respectively. Our results point out the SMx family of models need be improved for dimethyl sulfoxide solvent.

Performance of the SMD and SM8 models for predicting solvation free energy of neutral solutes in methanol, dimethyl sulfoxide and acetonitrile

NASA Astrophysics Data System (ADS)

Zanith, Caroline C.; Pliego, Josefredo R.

2015-03-01

The continuum solvation models SMD and SM8 were developed using 2,346 solvation free energy values for 318 neutral molecules in 91 solvents as reference. However, no solvation data of neutral solutes in methanol was used in the parametrization, while only few solvation free energy values of solutes in dimethyl sulfoxide and acetonitrile were used. In this report, we have tested the performance of the models for these important solvents. Taking data from literature, we have generated solvation free energy, enthalpy and entropy values for 37 solutes in methanol, 21 solutes in dimethyl sulfoxide and 19 solutes in acetonitrile. Both SMD and SM8 models have presented a good performance in methanol and acetonitrile, with mean unsigned error equal or less than 0.66 and 0.55 kcal mol-1 in methanol and acetonitrile, respectively. However, the correlation is worse in dimethyl sulfoxide, where the SMD and SM8 methods present mean unsigned error of 1.02 and 0.95 kcal mol-1, respectively. Our results point out the SMx family of models need be improved for dimethyl sulfoxide solvent.

Smart supramolecular sensing with cucurbit[n]urils: probing hydrogen bonding with SERS.

PubMed

de Nijs, Bart; Kamp, Marlous; Szabó, Istvan; Barrow, Steven J; Benz, Felix; Wu, Guanglu; Carnegie, Cloudy; Chikkaraddy, Rohit; Wang, Wenting; Deacon, William M; Rosta, Edina; Baumberg, Jeremy J; Scherman, Oren A

2017-12-04

Rigid gap nano-aggregates of Au nanoparticles formed using cucurbit[n]uril (CB[n]) molecules are used to investigate the competitive binding of ethanol and methanol in an aqueous environment. We show it is possible to detect as little as 0.1% methanol in water and a ten times higher affinity to methanol over ethanol, making this a useful technology for quality control in alcohol production. We demonstrate strong interaction effects in the SERS peaks, which we demonstrate are likely from the hydrogen bonding of water complexes in the vicinity of the CB[n]s.

Thermodynamic characteristics of the adsorption of 1,3,4-oxadiazoles and 1,2,4,5-tetrazines from methanol and water-methanol solutions onto hypercrosslinked polystyrene

NASA Astrophysics Data System (ADS)

Saifutdinov, B. R.; Davankov, V. A.; Il'in, M. M.

2017-03-01

The thermodynamic characteristics of the adsorption of several 1,3,4-oxadiazoles and 1,2,4,5- tetrazines from methanol and water-methanol solutions onto neutral hypercrosslinked polystyrene with a degree of crosslinking of 150% are determined via high performance liquid chromatography. It is shown how the obtained characteristics depend on the molecular structure of adsorbed substances and the composition of the liquid phase in which adsorption occurs.

Ionic Attachment as a Feasible Approach to Heterogenizing Anionic Solution Catalysts. The Carbonylation of Methanol,

DTIC Science & Technology

1980-08-01

carbonylation of methanol to acetic acid reaction is well suited for a demonstration of the feasibility and value of ionically binding a catalyst to a...approximate doubling of the reaction rate. This result suggests that a liquid flow system design in which there is a large catalyst to methanol ratio could...Heterogenizing Anionic Solution Catalysts . The Carbonylation of Methanol by Russell S. Drago, Eric D. Nyberg, Anton El A’mma and Alan Zombeck ABSTRACT -’Few

Towards neat methanol operation of direct methanol fuel cells: a novel self-assembled proton exchange membrane.

PubMed

Li, Jing; Cai, Weiwei; Ma, Liying; Zhang, Yunfeng; Chen, Zhangxian; Cheng, Hansong

2015-04-18

We report here a novel proton exchange membrane with remarkably high methanol-permeation resistivity and excellent proton conductivity enabled by carefully designed self-assembled ionic conductive channels. A direct methanol fuel cell utilizing the membrane performs well with a 20 M methanol solution, very close to the concentration of neat methanol.

Phytochemical screening, antiglycation and antioxidant activities of whole plant of Boerhavia repens L. from Cholistan, Pakistan.

PubMed

Nazneen, Fariha; Sheikh, Munir A; Jameel, Amir; Rahman, Ziaur

2016-05-01

Present study was aimed to explore a traditionally used indigenous medicinal plant Boerhavia repens (Nyctaginaceae family) of the Cholistan desert, Pakistan. Crude aqueous and methanolic extracts of the whole plant were investigated in vitro for preliminary phytochemical screening, antioxidant and antiglycation activities. Antioxidant activities were determined by total phenolic contents, 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging and inhibition of lipid peroxidation. For antiglycation activities browning production was noted and thiobarbituric acid (TBA) technique was used to determine glycation level. Boerhavia repens expressed considerable amounts of phytochemicals. Extract yield was found to be 4.59%-7.85% g/100g of dry matter with total phenolics ranging from 47.9- 190.77mg/GAE per g for aqueous and methanol extract respectively. Strong inhibitory effect was exhibited by methanolic extract in linoleic acid per oxidation system (86.11%, EC50=0.99mg/mL) and DPPH assay (88.65%, EC50=212.33μg/ml). In term of browning maximum inhibition (81.50%) was exhibited by methanolic extract at 37°C at third week of incubation. Both extracts expressed significant (P>0.05) and comparable inhibition of glycation level. In conclusion, Boerhavia repens showed promising antioxidant and antiglycation activities validating its therapeutic potential.

Hydrogen generation from water/methanol under visible light using aerogel prepared strontium titanate (SrTiO3) nanomaterials doped with ruthenium and rhodium metals

NASA Astrophysics Data System (ADS)

Kuo, Yenting; Klabunde, Kenneth J.

2012-07-01

Nanostructured strontium titanate visible-light-driven photocatalysts containing rhodium and ruthenium were synthesized by a modified aerogel synthesis using ruthenium chloride and rhodium nitrate as dopant precursors, and titanium isopropoxide and strontium metal as the metal sources. The well-defined crystalline SrTiO3 structure was confirmed by means of x-ray diffraction. After calcination at 500 °C, diffuse reflectance spectroscopy shows an increase in light absorption at 370 nm due to the presence of Rh3 + ; however an increase of the calcination temperature to 600 °C led to a decrease in intensity, probably due to a loss of surface area. An increase in the rhodium doping level also led to an increase in absorption at 370 nm however, the higher amounts of dopant lowered the photocatalytic activity. The modified aerogel synthesis allows greatly enhanced H2 production performance from an aqueous methanol solution under visible light irradiation compared with lower surface area conventional materials. We believe that this enhanced activity is due to the higher surface areas while high quality nanocrystalline materials are still obtained. Furthermore, the surface properties of these nanocrystalline aerogel materials are different, as exhibited by the higher activities in alkaline solutions, while conventional materials (obtained via high temperature solid-state synthesis methods) only exhibit reasonable hydrogen production in acidic solutions. Moreover, an aerogel synthesis approach gives the possibility of thin-film formation and ease of incorporation into practical solar devices.

Antidiabetic effects of Cuscuta reflexa Roxb. in streptozotocin induced diabetic rats.

PubMed

Rath, Diptirani; Kar, Durga Madhab; Panigrahi, Sandeep Kumar; Maharana, Laxmidhar

2016-11-04

Cuscuta reflexa Roxb. (Convolvulaceae) is traditionally used to treat diabetes mellitus by tribal people of north-east India and Bangladesh. To evaluate the anti-diabetic effects of methanol and aqueous extracts of the aerial parts of Cuscuta reflexa Roxb. in normal, glucose loaded and Streptozotocin (STZ) induced diabetic rats. The methanol (MECR) and aqueous (AECR) extracts (200 and 400mg/kg body weight) were administered orally to normal and diabetic rats with Metformin and solvent control as comparison groups. Long term effects like FBG, OGTT, lipid profile, HbA1c, body weight, histopathology of major organs, etc. were investigated. MECR and AECR did not have hypoglycemic effects in normal rats. Both AECR and MECR (400mg/kg) treatments showed significant reduction in blood glucose during OGTT in diabetic rats at 3h. Single oral administration of methanol and aqueous extracts (400mg/kg) to diabetic rats significantly reduced (p<0.05) blood glucose level to 61.90% and 55.39% respectively as compared to the Metformin group i.e. 68.32% at the end of 8h. MECR (400mg/kg body weight for 30 days to diabetic rats) showed a significant decrease (p<0.01) of blood glucose level to 60.00% as compared to other groups. The treatment also resulted an improvement in body weights, decreased HbA1c and restored lipid profile. Histopathological injury was not observed, rather repair of beta cells was seen in extract treated diabetic rats. Methanolic extract of C. reflexa has significant antidiabetic effects and improves metabolic alterations thereby justifying its traditional folkloric claims. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Thermodynamic and Structural Properties of Methanol-Water Solutions Using Non-Additive Interaction Models

PubMed Central

Zhong, Yang; Warren, G. Lee; Patel, Sandeep

2014-01-01

We study bulk structural and thermodynamic properties of methanol-water solutions via molecular dynamics simulations using novel interaction potentials based on the charge equilibration (fluctuating charge) formalism to explicitly account for molecular polarization at the atomic level. The study uses the TIP4P-FQ potential for water-water interactions, and the CHARMM-based (Chemistry at HARvard Molecular Mechanics) fluctuating charge potential for methanol-methanol and methanol-water interactions. In terms of bulk solution properties, we discuss liquid densities, enthalpies of mixing, dielectric constants, self-diffusion constants, as well as structural properties related to local hydrogen bonding structure as manifested in radial distribution functions and cluster analysis. We further explore the electronic response of water and methanol in the differing local environments established by the interaction of each species predominantly with molecules of the other species. The current force field for the alcohol-water interaction performs reasonably well for most properties, with the greatest deviation from experiment observed for the excess mixing enthalpies, which are predicted to be too favorable. This is qualitatively consistent with the overestimation of the methanol-water gas-phase interaction energy for the lowest-energy conformer (methanol as proton donor). Hydration free energies for methanol in TIP4P-FQ water are predicted to be −5.6±0.2 kcal/mole, in respectable agreement with the experimental value of −5.1 kcal/mole. With respect to solution micro-structure, the present cluster analysis suggests that the micro-scale environment for concentrations where select thermodynamic quantities reach extremal values is described by a bi-percolating network structure. PMID:18074339

Phytochemical analysis, antioxidant, antistress, and nootropic activities of aqueous and methanolic seed extracts of ladies finger (Abelmoschus esculentus L.) in mice.

PubMed

Doreddula, Sathish Kumar; Bonam, Srinivasa Reddy; Gaddam, Durga Prasad; Desu, Brahma Srinivasa Rao; Ramarao, Nadendla; Pandy, Vijayapandi

2014-01-01

Abelmoschus esculentus L. (ladies finger, okra) is a well-known tropical vegetable, widely planted from Africa to Asia and from South Europe to America. In the present study, we investigated the in vitro antioxidant capacity and in vivo protective effect of the aqueous and methanolic seed extracts of Abelmoschus esculentus against scopolamine-induced cognitive impairment using passive avoidance task and acute restraining stress-induced behavioural and biochemical changes using elevated plus maze (EPM) and forced swimming test (FST) in mice. Our results demonstrated that the pretreatment of mice with aqueous and methanolic seed extracts of Abelmoschus esculentus (200 mg/kg, p.o.) for seven days significantly (P < 0.01) attenuated scopolamine-induced cognitive impairment in the passive avoidance test. In addition, these extracts significantly reduced the blood glucose, corticosterone, cholesterol, and triglyceride levels elevated by acute restraint stress and also significantly increased the time spent in open arm in EPM and decreased the immobility time in FST. It has also been revealed that these extracts showed a significant antioxidant activity and no signs of toxicity or death up to a dose of 2000 mg/kg, p.o. These results suggest that the seed extracts of Abelmoschus esculentus L. possess antioxidant, antistress, and nootropic activities which promisingly support the medicinal values of ladies finger as a vegetable.

Phytochemical Analysis, Antioxidant, Antistress, and Nootropic Activities of Aqueous and Methanolic Seed Extracts of Ladies Finger (Abelmoschus esculentus L.) in Mice

PubMed Central

Doreddula, Sathish Kumar; Bonam, Srinivasa Reddy; Gaddam, Durga Prasad; Desu, Brahma Srinivasa Rao; Ramarao, Nadendla; Pandy, Vijayapandi

2014-01-01

Abelmoschus esculentus L. (ladies finger, okra) is a well-known tropical vegetable, widely planted from Africa to Asia and from South Europe to America. In the present study, we investigated the in vitro antioxidant capacity and in vivo protective effect of the aqueous and methanolic seed extracts of Abelmoschus esculentus against scopolamine-induced cognitive impairment using passive avoidance task and acute restraining stress-induced behavioural and biochemical changes using elevated plus maze (EPM) and forced swimming test (FST) in mice. Our results demonstrated that the pretreatment of mice with aqueous and methanolic seed extracts of Abelmoschus esculentus (200 mg/kg, p.o.) for seven days significantly (P < 0.01) attenuated scopolamine-induced cognitive impairment in the passive avoidance test. In addition, these extracts significantly reduced the blood glucose, corticosterone, cholesterol, and triglyceride levels elevated by acute restraint stress and also significantly increased the time spent in open arm in EPM and decreased the immobility time in FST. It has also been revealed that these extracts showed a significant antioxidant activity and no signs of toxicity or death up to a dose of 2000 mg/kg, p.o. These results suggest that the seed extracts of Abelmoschus esculentus L. possess antioxidant, antistress, and nootropic activities which promisingly support the medicinal values of ladies finger as a vegetable. PMID:25401145

Stress corrosion behavior of Ru-enhanced alpha-beta titanium alloys in methanol solutions

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

Schutz, R.W.; Horrigan, J.M.; Bednarowicz, T.A.

1998-12-31

Conservative, practical guidelines for the minimum water content required to prevent methanolic stress corrosion cracking (SCC) of Ti-6Al-4V-Ru and Ti-3Al-2.5V-Ru alloy tubulars have been developed from slow strain rate testing in plain and acidified NaCl-saturated methanol-water solutions at 25 C. A minimum methanol water content of 10 wt.% is proposed for Ti-6Al-4V-Ru, whereas 2-3 wt.% is sufficient for the lower strength Ti-3Al-2.5V-Ru alloy. Although HCl-acidification aggravated methanolic SCC, intermixing of methanol with crude oil or pure hydrocarbons, H{sub 2}S gas saturation, and/or increasing temperature diminished cracking susceptibility in these alloy tubulars.

Self-spinning nanoparticle laden microdroplets for sensing and energy harvesting.

PubMed

Bhattacharjee, Mitradip; Pasumarthi, Viswanath; Chaudhuri, Joydip; Singh, Amit Kumar; Nemade, Harshal; Bandyopadhyay, Dipankar

2016-03-21

Exposure of a volatile organic vapour could set in powerful rotational motion a microdroplet composed of an aqueous salt solution loaded with metal nanoparticles. The solutal Marangoni motion on the surface originating from the sharp difference in the surface tension of water and organic vapour stimulated the strong vortices inside the droplet. The vapour sources of methanol, ethanol, diethyl ether, toluene, and chloroform stimulated motions of different magnitudes could easily be correlated to the surface tension gradient on the drop surface. Interestingly, when the nanoparticle laden droplet of aqueous salt solution was connected to an external electric circuit through a pair of electrodes, an ∼85-95% reduction in the electrical resistance was observed across the spinning droplet. The extent of reduction in the resistance was found to have a correlation with the difference in the surface tension of the vapour source and the water droplet, which could be employed to distinguish the vapour sources. Remarkably, the power density of the same prototype was estimated to be around 7 μW cm(-2), which indicated the potential of the phenomenon in converting surface energy into electrical in a non-destructive manner and under ambient conditions. Theoretical analysis uncovered that the difference in the ζ-potential near the electrodes was the major reason for the voltage generation. The prototype could also detect the repeated exposure and withdrawal of vapour sources, which helped in the development of a proof-of-concept detector to sense alcohol issuing out of the human breathing system.

[Determination of sennosides and degraded products in the process of sennoside metabolism by HPLC].

PubMed

Sun, Yan; Li, Xuetuo; Yu, Xingju

2004-01-01

A method for the separation and determination of sennosides A and B and the main composition (sennidins A and B) in degraded products of sennosides by linear gradient high performance liquid chromatography has been developed. Separation conditions were as follows: column, a Spherisorb C18 column (250 mm x 4.6 mm i.d., 10 microm); column temperature, 40 degrees C; detection wavelength, 360 nm; mobile phase A, 1.25% acetic acid aqueous solution; mobile phase B, methanol; linear gradient, 100% A --> (20 min) 100% B. The method is effective, quick, accurate and reproducible. The satisfactory results show that this new method has certain practical values as an approach of real-time analysis in the process of sennoside metabolism.

Fabrication of photocatalytically active vanadium oxide nanostructures via plasma route

NASA Astrophysics Data System (ADS)

Kajita, Shin; Yoshida, Tomoko; Ohno, Noriyasu; Ichino, Yusuke; Yoshida, Naoaki

2018-05-01

Plasma irradiation was used to create nanostructured vanadium oxide with potential commercial and industrial applications. Morphology changes were induced at the nano- and micro-meter scale, accompanied by the growth of helium nanobubbles. Micrometer-sized pillars, cube-shaped nanostructures, and fuzzy fiberform nanostructures were grown on the surface; the necessary conditions in terms of the incident ion energy and the surface temperature for those morphology changes were revealed. Hydrogen production experiments using a photocatalytic reaction with aqueous methanol solution were conducted on the fabricated samples. Enhanced H2 production was confirmed with the plasma irradiated nanostructured sample that had been oxidized in air atmosphere. Photocatalytically inactive vanadium oxide exhibited a high photocatalytic activity after nanostructurization of the surface by helium plasma irradiation.

[Study on HPLC fingerprint of Alpinia officinarum].

PubMed

Deng, Yi-Feng; Feng, Li-Na; Luo, Hui

2011-09-01

To establish the chromatography fingerprint of Alpinia officinarum by HPLC. An optimum HPLC conditions which were obtained under the assessment of LC-MS were as follows: Shim-pack VP-ODS column (2.0 mm x 250 mm, 5 microm), 0.1% HAc aqueous solution as phase A, 15% Acetonitrile: 40% Methanol: 45% Tetrafuran as phase B, the flow rate was 0.20 mL/min, column temperature was 35 degrees C and UV detector was set at 280 nm. The HPLC fingerprint of Alpinia officinarum was established, the consensus 10 peaks and their relative retention times along with the ranges of relative area were determined. The method is reliable and stable and can be used for the quality control and identification of Alpinia officinarum.

Chemical approach to solvent removal during nanoencapsulation: its application to preparation of PLGA nanoparticles with non-halogenated solvent

NASA Astrophysics Data System (ADS)

Lee, Youngme; Sah, Eric; Sah, Hongkee

2015-11-01

The objective of this study was to develop a new oil-in-water emulsion-based nanoencapsulation method for the preparation of PLGA nanoparticles using a non-halogenated solvent. PLGA (60-150 mg) was dissolved in 3 ml of methyl propionate, which was vortexed with 4 ml of a 0.5-4 % polyvinyl alcohol solution. This premix was sonicated for 2 min, added into 30 ml of the aqueous polyvinyl alcohol solution, and reacted with 3 ml of 10 N NaOH. Solvent removal was achieved by the alkaline hydrolysis of methyl propionate dissolved in an aqueous phase into water-soluble methanol and sodium propionate. It was a simple but effective technique to quickly harden nanoemulsion droplets into nanoparticles. The appearing PLGA nanoparticles were recovered by ultracentrifugation and/or dialysis, lyophilized with trehalose, and redispersed by water. This nanoencapsulation technique permitted a control of their mean diameters over 151.7 ± 3.8 to 440.2 ± 22.2 nm at mild processing conditions. When the aqueous polyvinyl alcohol concentration was set at ≥1 %, nanoparticles showed uniform distributions with polydispersity indices below 0.1. There were no significant changes in their mean diameters and size distribution patterns before and after lyophilization. When mestranol was encapsulated into nanoparticles, the drug was completely nanoencapsulated: depending on experimental conditions, their encapsulation efficiencies were determined to be 99.4 ± 7.2 to 105.8 ± 6.3 %. This simple, facile nanoencapsulation technique might have versatile applications for the preparation of polymeric nanoparticulate dosage forms.

Tyrosinase Inhibitory Activities of Carissa opaca Stapf ex Haines Roots Extracts and Their Phytochemical Analysis

PubMed Central

Malik, Wajeeha; Ahmed, Dildar; Izhar, Sania

2017-01-01

Objective: Carissa opaca is a medicinal plant with rich folkloric applications. The present research was conducted to explore the tyrosinase inhibitory potential of aqueous decoction (AD) and methanolic extract (ME) of roots of C. opaca and its fractions in various solvents and their phytochemical analysis. Materials and Methods: AD of the dried powdered roots of C. opaca was prepared by boiling in water. ME was prepared by cold maceration. Its fractions were obtained in solvents of increasing polarity, i.e., hexane, chloroform, ethyl acetate, n-butanol, and water. The biomass left after extraction with methanol was boiled in water to get its decoction Biomass aqueous decoction (BAD). Tyrosinase inhibitory activities of the samples were studied according to a reported method. Chemical compounds in the samples were identified by gas chromatography-mass spectrometry (GC-MS). Results: The AD, BAD, and ME and its fractions displayed remarkable tyrosinase inhibitory activity. The IC50 of AD was 23.33 μg/mL as compared to 15.80 μg/mL of the standard arbutin and that of BAD was 21.24 μg/mL. The IC50 of ME was 34.76 μg/mL while that of hexane, chloroform, ethyl acetate, n-butanolic, and aqueous fractions was 21.0, 44.73, 43.40, 27.66, and 25.06 μg/mL, respectively. The hexane fraction was thus most potent followed by aqueous fraction. By phytochemical analysis, campesterol, stigmasterol, gamma-sitosterol, alpha-amyrin, 9,19-cyclolanostan-3-ol, 24-methylene-,(3 β)-, lupeol, lup-20(29)-en-3-one, lup-20(29)-en-3-ol, acetate,(3 β)-, 2(1H) naphthalenone, 3,5,6,7,8,8a-hexahydro-4,8a-dimethyl-6-(1-methylethenyl)-, and 2,3,3-trimethyl-2-(3-methylbuta-1,3-dienyl)-6-methylenecyclohexanone were identified in the extracts by GC-MS. Other compounds included fatty acids and their esters. Some of these compounds are being first time reported here from this plant. Conclusions: The roots extracts exhibited considerable tyrosinase inhibitory activities, alluding to a possible application of the plant in cosmetic as whitening agent subject to further pharmacological studies. SUMMARY The present study aimed to explore the tyrosinase inhibitory potential of aqueous decoction and methanolic extract of roots of Carissa opaca and its fractions in various solvents and their phytochemical constituents. GCMS analysis was conducted to identify the phytochemicals. The extracts and fractions of C. opaca roots showed remarkable anti-tyrosinase activities alluding to their possible application to treat disorders related to overproduction of melanin. Abbreviations used: AD: Aqueous decoction; ME: Methanolic extract; BAD: Biomass aqueous decoction; GC-MS: Gas chromatography-mass spectrometry. PMID:29142412

Antioxidant properties of the red alga Asparagopsis taxiformis collected on the North West Algerian coast

PubMed Central

Mellouk, Zoheir; Benammar, Ilhem; Krouf, Djamil; Goudjil, Makhlouf; Okbi, Meriem; Malaisse, Willy

2017-01-01

The aim of the present study was to evaluate the total phenolic and lipid content, fatty acids profiles and in vitro antioxidant activities of aqueous and solvent extracts of the red seaweed Asparagopsis taxiformis, through six different investigations. The present study demonstrated that phenol contents (mg gallic acid/g dry weight) were highest in the aqueous and methanolic extracts, followed by the ethanolic, hydroethanolic and hydromethanolic extracts. The lowest phenol contents were identified in the three remaining extracts: Butanolic, petroleum ether and acetone extracts. Furthermore, the total lipid content of the algae powder amounted to 2.85% of dry weight. The fatty acid methyl ester profiles analysed by gas-liquid chromatography represented indicated that fatty acids comprised 91.0±0.3% of total algae lipids. The saturated to unsaturated fatty acid contents amounted to 23.2±0.1 and 67.9±0.4% respectively. C13:0 (tridecanoate), C15:0 (pentadecanoate) and C17:0 (heptadecanoate) represented 47.4% of the total saturated fatty acids. Notably, the two most abundant unsaturated fatty acids, C15:1 (pentadecenoate) and C18:2 (octadecadienoate) represented 13.4 and 11.4% respectively, of the total unsaturated fatty acid content. Furthermore, the results of the antioxidant screening performed at 1.0 mg/ml, revealed that aqueous and methanolic extracts exhibited higher inhibition against superoxide and nitric oxide radicals and excellent radical scavenging activity [with half maximal inhibitory concentration (IC50) values 5.1 and 15.0 µg/ml, respectively], demonstrating improved antioxidant behavior when compared with standard ascorbic acid (which has an IC50 value of 3.7 µg/ml). Scavenging activity of the aqueous and methanolic extracts exhibited a strong peroxidation inhibition against linoleic acid emulsion system at a concentration of 300 µg/ml in comparison to the butylated hydroxyltoluene. Although all the studied extracts exhibited ferric reducing power, the aqueous and methanolic extracts had greater hydrogen donating ability. By contrast, hydromethanolic, ethanolic, hydroethanolic, butanolic, acetone and petroleum ether extracts exhibited weak antioxidant behavior. The antioxidant activity of potent seaweed species identified in the current study means that as well as being used as a functional food, they may be developed as novel pharmaceutical compounds and may be used as anti-ageing agents. PMID:28587401

Antisecretory activity of plants used to treat gastrointestinal disorders in Mexico.

PubMed

Velázquez, Claudia; Calzada, Fernando; Torres, Javier; González, Felipe; Ceballos, Guillermo

2006-01-03

Aqueous and methanolic extracts from 26 medicinal plants used in Mexico to treat gastrointestinal disorders were screened to evaluate their antisecretory activity on cholera toxin-induced intestinal secretion in rat jejunal loops model. Extracts were tested at a dose of 300 mg/kg. From 56 samples tested, both extracts from Chiranthodendron pentadactylon, Hippocratea excelsa and Ocimum basilicum were the most potent with inhibition values ranging from 68.0 to 87.6%. On the other hand, the methanolic extract of Geranium mexicanum (aerial parts) and the aqueous extract of Bocconia frutescens showed the highest activity with inhibition values of 93.4 and 86.0%, respectively. The results obtained in this study give some scientific support to the use of the Mexican medicinal plants employed for the treatment of gastrointestinal disorders such as diarrhea.

Photodegradation of hexythiazox in different solvent systems under the influence of ultraviolet light and sunlight in the presence of TiO2, H2O2, and KNO3 and identification of the photometabolites.

PubMed

Mandal, Sudeb; Joardar, Soumen; Das, Saktipada; Bhattacharyya, Anjan

2011-11-09

The photodegradation of the carboxamide acaricide hexythiazox in three different solvent systems (aqueous methanolic, aqueous isopropanolic, and aqueous acetonitrilic solutions) in the presence of H(2)O(2), KNO(3), and TiO(2) under ultraviolet (UV) light (λ(max) ≥ 250 nm) and sunlight (λ(max) ≥290 nm) has been assessed in this work. The kinetics of photodecomposition of hexythiazox and the identification of photoproducts were carried out using liquid chromatography-mass spectrometry. The rate of photodecomposition of hexythiazox in different solvents followed first-order kinetics in both UV radiation and natural sunlight, and the degradation rates were faster under UV light than under sunlight. Hexythiazox was found to be more efficiently photodegraded in the presence of TiO(2) than in the presence of H(2)O(2) and KNO(3). Two major photoproducts were separated in pure form using column chromatography and identified according to IR, (1)H NMR, and mass spectral information as cyclohexylamine and 5-(4-chlorophenyl)-4-methylthiazolidin-2-one. Another nine photoproducts were identified according to LC-MS/MS spectral information. The plausible photodegradation pathways of hexythiazox were proposed according to the structures of the photoproducts.

Using design of experiments to optimize derivatization with methyl chloroformate for quantitative analysis of the aqueous phase from hydrothermal liquefaction of biomass.

PubMed

Madsen, René Bjerregaard; Jensen, Mads Mørk; Mørup, Anders Juul; Houlberg, Kasper; Christensen, Per Sigaard; Klemmer, Maika; Becker, Jacob; Iversen, Bo Brummerstedt; Glasius, Marianne

2016-03-01

Hydrothermal liquefaction is a promising technique for the production of bio-oil. The process produces an oil phase, a gas phase, a solid residue, and an aqueous phase. Gas chromatography coupled with mass spectrometry is used to analyze the complex aqueous phase. Especially small organic acids and nitrogen-containing compounds are of interest. The efficient derivatization reagent methyl chloroformate was used to make analysis of the complex aqueous phase from hydrothermal liquefaction of dried distillers grains with solubles possible. A circumscribed central composite design was used to optimize the responses of both derivatized and nonderivatized analytes, which included small organic acids, pyrazines, phenol, and cyclic ketones. Response surface methodology was used to visualize significant factors and identify optimized derivatization conditions (volumes of methyl chloroformate, NaOH solution, methanol, and pyridine). Twenty-nine analytes of small organic acids, pyrazines, phenol, and cyclic ketones were quantified. An additional three analytes were pseudoquantified with use of standards with similar mass spectra. Calibration curves with high correlation coefficients were obtained, in most cases R (2)  > 0.991. Method validation was evaluated with repeatability, and spike recoveries of all 29 analytes were obtained. The 32 analytes were quantified in samples from the commissioning of a continuous flow reactor and in samples from recirculation experiments involving the aqueous phase. The results indicated when the steady-state condition of the flow reactor was obtained and the effects of recirculation. The validated method will be especially useful for investigations of the effect of small organic acids on the hydrothermal liquefaction process.

Microfluidic distillation chip for methanol concentration detection.

PubMed

Wang, Yao-Nan; Liu, Chan-Chiung; Yang, Ruey-Jen; Ju, Wei-Jhong; Fu, Lung-Ming

2016-03-17

An integrated microfluidic distillation system is proposed for separating a mixed ethanol-methanol-water solution into its constituent components. The microfluidic chip is fabricated using a CO2 laser system and comprises a serpentine channel, a boiling zone, a heating zone, and a cooled collection chamber filled with de-ionized (DI) water. In the proposed device, the ethanol-methanol-water solution is injected into the microfluidic chip and driven through the serpentine channel and into the collection chamber by means of a nitrogen carrier gas. Following the distillation process, the ethanol-methanol vapor flows into the collection chamber and condenses into the DI water. The resulting solution is removed from the collection tank and reacted with a mixed indicator. Finally, the methanol concentration is inversely derived from the absorbance measurements obtained using a spectrophotometer. The experimental results show the proposed microfluidic system achieves an average methanol distillation efficiency of 97%. The practicality of the proposed device is demonstrated by detecting the methanol concentrations of two commercial fruit wines. It is shown that the measured concentration values deviate by no more than 3% from those obtained using a conventional bench top system. Copyright © 2016 Elsevier B.V. All rights reserved.

Waste-to-methanol: Process and economics assessment.

PubMed

Iaquaniello, Gaetano; Centi, Gabriele; Salladini, Annarita; Palo, Emma; Perathoner, Siglinda; Spadaccini, Luca

2017-11-01

The waste-to-methanol (WtM) process and related economics are assessed to evidence that WtM is a valuable solution both from economic, strategic and environmental perspectives. Bio-methanol from Refuse-derived-fuels (RdF) has an estimated cost of production of about 110€/t for a new WtM 300t/d plant. With respect to waste-to-energy (WtE) approach, this solution allows various advantages. In considering the average market cost of methanol and the premium as biofuel, the WtM approach results in a ROI (Return of Investment) of about 29%, e.g. a payback time of about 4years. In a hybrid scheme of integration with an existing methanol plant from natural gas, the cost of production becomes a profit even without considering the cap for bio-methanol production. The WtM process allows to produce methanol with about 40% and 30-35% reduction in greenhouse gas emissions with respect to methanol production from fossil fuels and bio-resources, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

Methanol-enhanced removal and metabolic conversion of formaldehyde by a black soybean from formaldehyde solutions.

PubMed

Tan, Hao; Xiong, Yun; Li, Kun-Zhi; Chen, Li-Mei

2017-02-01

Methanol regulation of some biochemical and physiological characteristics in plants has been documented in several references. This study showed that the pretreatment of methanol with an appropriate concentration could stimulate the HCHO uptake by black soybean (BS) plants. The process of methanol-stimulated HCHO uptake by BS plants was optimized using the Central Composite Design and response surface methodology for the three variables, methanol concentration, HCHO concentration, and treatment time. Under optimized conditions, the best stimulation effect of methanol on HCHO uptake was obtained. 13 C-NMR analysis indicated that the H 13 CHO metabolism produced H 13 COOH, [2- 13 C]Gly, and [3- 13 C]Ser in BS plant roots. Methanol pretreatment enhanced the metabolic conversion of H 13 CHO in BS plant roots, which consequently increased HCHO uptake by BS plants. Therefore, methanol pretreatment might be used to increase HCHO uptake by plants in the phytoremediation of HCHO-polluted solutions.

Computing pKa Values with a Mixing Hamiltonian Quantum Mechanical/Molecular Mechanical Approach.

PubMed

Liu, Yang; Fan, Xiaoli; Jin, Yingdi; Hu, Xiangqian; Hu, Hao

2013-09-10

Accurate computation of the pKa value of a compound in solution is important but challenging. Here, a new mixing quantum mechanical/molecular mechanical (QM/MM) Hamiltonian method is developed to simulate the free-energy change associated with the protonation/deprotonation processes in solution. The mixing Hamiltonian method is designed for efficient quantum mechanical free-energy simulations by alchemically varying the nuclear potential, i.e., the nuclear charge of the transforming nucleus. In pKa calculation, the charge on the proton is varied in fraction between 0 and 1, corresponding to the fully deprotonated and protonated states, respectively. Inspired by the mixing potential QM/MM free energy simulation method developed previously [H. Hu and W. T. Yang, J. Chem. Phys. 2005, 123, 041102], this method succeeds many advantages of a large class of λ-coupled free-energy simulation methods and the linear combination of atomic potential approach. Theory and technique details of this method, along with the calculation results of the pKa of methanol and methanethiol molecules in aqueous solution, are reported. The results show satisfactory agreement with the experimental data.

Tautomeric and Microscopic Protonation Equilibria of Anthranilic Acid and Its Derivatives.

PubMed

Zapała, Lidia; Woźnicka, Elżbieta; Kalembkiewicz, Jan

2014-01-01

The acid-base chemistry of three zwitterionic compounds, namely anthranilic (2-aminobenzoic acid), N -methylanthranilic and N -phenylanthranilic acid has been characterized in terms of the macroconstants K a1 , K a2 , the isoelectric point p H I , the tautomerization constant K z and microconstants k 11 , k 12 , k 21 , k 22 . The potentiometric titration method was used to determine the macrodissociation constants. Due to the very poor water solubility of N -phenylanthranilic acid the dissociation constants p K a1 and p K a2 were determined in MDM-water mixtures [MDM is a co-solvent mixture, consisting of equal volumes of methanol (MeOH), dioxane and acetonitrile (MeCN)]. The Yasuda-Shedlovsky extrapolation procedure has been used to obtain the values of p K a1 and p K a2 in aqueous solutions. The p K a1 and p K a2 values obtained by this method are 2.86 ± 0.01 and 4.69 ± 0.03, respectively. The tautomerization constant K z describing the equilibrium between unionized form ⇌ zwitterionic form was evaluated by the K z method based on UV-VIS spectrometry. The method uses spectral differences between the zwitterionic form (found at isoelectric pH in aqueous solution) and the unionized form (formed in an organic solvent of low dielectric constant). The highest value of the K z constant has been observed in the case of N -methylantranilic acid (log 10 K z  = 1.31 ± 0.04). The values of log 10 K z for anthranilic and N -phenylanthranilic acids are similar and have values of 0.93 ± 0.03 and 0.90 ± 0.05, respectively. The results indicate that the tested compounds, in aqueous solution around the isoelectric point pH I , occur mainly in the zwitterionic form. Moreover, the influence of the type of substituent and pH of the aqueous phase on the equilibrium were analyzed with regard to the formation and the coexistence of different forms of the acids in the examined systems.

Enhanced adsorption of perfluorooctane sulfonate and perfluorooctanoate by bamboo-derived granular activated carbon.

PubMed

Deng, Shubo; Nie, Yao; Du, Ziwen; Huang, Qian; Meng, Pingping; Wang, Bin; Huang, Jun; Yu, Gang

2015-01-23

A bamboo-derived granular activated carbon with large pores was successfully prepared by KOH activation, and used to remove perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) from aqueous solution. The granular activated carbon prepared at the KOH/C mass ratio of 4 and activation temperature of 900°C had fast and high adsorption for PFOS and PFOA. Their adsorption equilibrium was achieved within 24h, which was attributed to their fast diffusion in the micron-sized pores of activated carbon. This granular activated carbon exhibited the maximum adsorbed amount of 2.32mmol/g for PFOS and 1.15mmol/g for PFOA at pH 5.0, much higher than other granular and powdered activated carbons reported. The activated carbon prepared under the severe activation condition contained many enlarged pores, favorable for the adsorption of PFOS and PFOA. In addition, the spent activated carbon was hardly regenerated in NaOH/NaCl solution, while the regeneration efficiency was significantly enhanced in hot water and methanol/ethanol solution, indicating that hydrophobic interaction was mainly responsible for the adsorption. The regeneration percent was up to 98% using 50% ethanol solution at 45°C. Copyright © 2014 Elsevier B.V. All rights reserved.

Development of new composite biosorbents from olive pomace wastes

NASA Astrophysics Data System (ADS)

Pagnanelli, Francesca; Viggi, Carolina Cruz; Toro, Luigi

2010-06-01

In this study olive pomace was used as a source of binding substances for the development of composite biosorbents to be used in heavy metal removal from aqueous solutions. The aim was to obtain biosorbent material with an increased concentration of binding sites. The effects of two different extraction procedures (one using only methanol and the other one hexane followed by methanol) on the binding properties of olive pomace were tested by potentiometric titrations and batch biosorption tests for copper and cadmium removal. Titration modelling evidenced that both kinds of extractions generated a solid with a reduced amount of protonatable sites. Biosorption tests were organized according to full factorial designs. Analysis of variance denoted that both kinds of extractions determined a statistically significant negative effect on metal biosorption. In the case of cadmium extractions also determined a significant decrease of selectivity with respect to olive pomace. When the acid-base and binding properties of the substances extracted were determined, they were adsorbed onto a synthetic resin (octadecylsilane) and calcium alginate beads. In this way two kinds of composite biosorbents have been obtained both having an increased concentration of binding substances with respect to native olive pomace, also working more efficiently in metal removal.

Co@Co3 O4 @PPD Core@bishell Nanoparticle-Based Composite as an Efficient Electrocatalyst for Oxygen Reduction Reaction.

PubMed

Wang, Zhijuan; Li, Bing; Ge, Xiaoming; Goh, F W Thomas; Zhang, Xiao; Du, Guojun; Wuu, Delvin; Liu, Zhaolin; Andy Hor, T S; Zhang, Hua; Zong, Yun

2016-05-01

Durable electrocatalysts with high catalytic activity toward oxygen reduction reaction (ORR) are crucial to high-performance primary zinc-air batteries (ZnABs) and direct methanol fuel cells (DMFCs). An efficient composite electrocatalyst, Co@Co3 O4 core@shell nanoparticles (NPs) embedded in pyrolyzed polydopamine (PPD) is reported, i.e., in Co@Co3 O4 @PPD core@bishell structure, obtained via a three-step sequential process involving hydrothermal synthesis, high temperature calcination under nitrogen atmosphere, and gentle heating in air. With Co@Co3 O4 NPs encapsulated by ultrathin highly graphitized N-doped carbon, the catalyst exhibits excellent stability in aqueous alkaline solution over extended period and good tolerance to methanol crossover effect. The integration of N-doped graphitic carbon outer shell and ultrathin nanocrystalline Co3 O4 inner shell enable high ORR activity of the core@bishell NPs, as evidenced by ZnABs using catalyst of Co@Co3 O4 @PPD in air-cathode which delivers a stable voltage profile over 40 h at a discharge current density of as high as 20 mA cm(-2) . © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Aqueous electrolytes for redox flow battery systems

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

Liu, Tianbiao; Li, Bin; Wei, Xiaoliang

An aqueous redox flow battery system includes an aqueous catholyte and an aqueous anolyte. The aqueous catholyte may comprise (i) an optionally substituted thiourea or a nitroxyl radical compound and (ii) a catholyte aqueous supporting solution. The aqueous anolyte may comprise (i) metal cations or a viologen compound and (ii) an anolyte aqueous supporting solution. The catholyte aqueous supporting solution and the anolyte aqueous supporting solution independently may comprise (i) a proton source, (ii) a halide source, or (iii) a proton source and a halide source.

Introducing Urtica dioica, A Native Plant of Khuzestan, As an Antibacterial Medicinal Plant.

PubMed

Motamedi, Hossein; Seyyednejad, Seyyed Mansour; Bakhtiari, Ameneh; Vafaei, Mozhan

2014-11-01

Urtica dioica is a flowering plant with long history of use in folk medicine and as a food source. This study examined in vitro antibacterial potential of alcoholic extracts of U. dioica. Hydroalcoholic extracts from aerial parts were prepared using aqueous solution of ethanol and methanol and their inhibitory effects against clinical isolates was examined by disc diffusion method at different doses. Minimum inhibitory concentrations (MIC) and minimum bactericidal concentration (MBC) indexes were also investigated. The scanning electron microscopy (SEM) analysis was also performed to find structural changes of affected bacteria consequent to exposing with extracts. Both extracts were active against Bacillus cereus, Staphylococcus aureus, Staphylococcus epidermidis, and Escherichia coli with respectively 16, 10, 18, and 14 mm (methanolic) and 11, 9, 17, and 16 mm (ethanolic) inhibition zone. The MIC of ethanolic extract against S. epidermidis and E. coli was respectively 10 and 40 mg/mL. The MIC of methanolic extract against S. aureus and S. epidermidis was 40 and 10 mg/mL, respectively. The MBC was found only for S. epidermidis (20 mg/mL). In SEM analysis the round shape of S. epidermidis was changed and irregular shapes were appeared, which suggest that the main target of these extracts was cell wall. Extracts of U. dioica showed significant antibacterial effect against some clinically important pathogenic bacteria. Based on the obtained results it can be concluded that U. dioica is useful as antibacterial and bactericidal agent in treating infectious diseases.

Acute Oral Mammalian Toxicity and Effect of Solvents on Efficacy of Maerua edulis (Gilg. & Ben.) De Wolf against Rhipicephalus (Boophilus) decoloratus Koch, 1844 (Acarina: Ixodidae), Tick Larvae

PubMed Central

Mvumi, Brighton M.; Maramba, Tatenda

2016-01-01

Efficacy and toxicity of aqueous and organic solvents extracts of Maerua edulis against ticks and mice, respectively, were determined. Ground leaves were extracted separately using cold water, cold water plus surfactant (1% v/v liquid soap), hot water plus surfactant, hexane, or methanol to make 25% w/v stock solutions from which serial dilutions of 5, 10, 20, and 25% were made. For each concentration, 20 Rhipicephalus decoloratus tick larvae were put in filter papers impregnated with extracts and incubated for 48 h at 27°C and 85–90% RH for mortality observation after 24 h and 48 h. In the toxicity experiment, hot water plus surfactant treatments of 5, 10, 20, and 25% (w/v) M. edulis were administered in suspension per os to sexually mature Balb/C mice and observed for clinical signs and mortality for 72 h. Larvae mortality was highest (>98%) in methanol-extracted M. edulis treatments (20 and 25%), which was not different from the amitraz-based control (Tickbuster®). Mortality was also higher in the hot water than in cold water plus surfactant treatments (P < 0.05). No postadministration adverse health effects were observed in the mice. These results suggest that M. edulis is an effective tick remedy best extracted using methanol or hot water plus surfactant. PMID:27660762

Novel crosslinked membranes based on sulfonated poly(ether ether ketone) for direct methanol fuel cells.

PubMed

Zhu, Yuanqin; Zieren, Shelley; Manthiram, Arumugam

2011-07-14

Novel covalently crosslinked membranes based on sulfonated poly(ether ether ketone) and carboxylated polysulfone exhibit much lower methanol crossover and better performance in direct methanol fuel cells at 65 °C in 1 and 2 M methanol solutions compared to Nafion 115 membranes.

Castalagin from Anogeissus leiocarpus mediates the killing of Leishmania in vitro.

PubMed

Shuaibu, M N; Pandey, K; Wuyep, P A; Yanagi, T; Hirayama, K; Ichinose, A; Tanaka, T; Kouno, I

2008-11-01

Stem barks of Anogeissus leiocarpus and Terminalia avicennoides widely used in Africa for treatment of some parasitic diseases were collected and made into methanolic extracts. The extracts were tested on four strains of promastigote forms of Leishmania in vitro. Solvent fractionation in aqueous, butanolic, and ethyl acetate layer indicated butanol and aqueous fractions to have a superior leishmanicidal activity. Chromatographic separation of the butanolic fraction on Sephadex LH-20 followed by nuclear magnetic resonance and correlation high-performance liquid chromatography revealed the presence of known hydrolyzable tannins and some related compounds-with castalagin as the major compound. The observed activity ranged from 62.5 to > or =150, 112.5 to > or =500, and 55 to >150 microg/ml for the crude methanolic extract, different solvent fractions, and the isolated compounds, respectively, on the four different Leishmania strains.

Characterization of crude glycerol from biodiesel plants.

PubMed

Hu, Shengjun; Luo, Xiaolan; Wan, Caixia; Li, Yebo

2012-06-13

Characterization of crude glycerol is very important to its value-added conversion. In this study, the physical and chemical properties of five biodiesel-derived crude glycerol samples were determined. Three methods, including iodometric-periodic acid method, high performance liquid chromatography (HPLC), and gas chromatography (GC), were shown to be suitable for the determination of glycerol content in crude glycerol. The compositional analysis of crude glycerol was successfully achieved by crude glycerol fractionation and characterization of the obtained fractions (aqueous and organic) using titrimetric, HPLC, and GC analyses. The aqueous fraction consisted mainly of glycerol, methanol, and water, while the organic fraction contained fatty acid methyl esters (FAMEs), free fatty acids (FFAs), and glycerides. Despite the wide variations in the proportion of their components, all raw crude glycerol samples were shown to contain glycerol, soap, methanol, FAMEs, water, glycerides, FFAs, and ash.

Effect of gamma radiation on antioxidant capacity of green tea, yerba mate, and chamomile tea as evaluated by different methods

NASA Astrophysics Data System (ADS)

Gerolis, Luanai Grazieli Luquini; Lameiras, Fernando Soares; Krambrock, Klaus; Neves, Maria Jose.

2017-01-01

Tea is a traditional plant extract with important cultural ties. It is the most widely consumed beverage in the world. Tea consumption has some health benefits including antioxidant stimulus. Gamma radiation is currently used to control of postharvest pathogens on tea herb. However, free radicals can be generated, which consumes antioxidant molecules. A positive relation was found between radiation doses used and free radicals generation in green tea (Camellia sinensis), yerba mate (Ilex paraguariensis), and chamomile tea (Matricaria recutita). Total antioxidant capacity (TAC) of aqueous and methanol extracts of these herbs was determined by various methods to compare the effect of irradiation of herb on antioxidant capacity of the extracts. TAC was evaluated by measuring: total phenols (decreased with irradiation in mate and green teas), total flavonoids (stable in aqueous extracts and decreased with irradiation in methanol extract of mate and chamomile), Trolox equivalent or ABTS (unchanged under irradiation), DPPH* scavenging capacity (stable on aqueous extract but diminished in methanol extract after irradiation), β carotene/acid linoleic ability (stable with the exception of chamomile tea that increased after irradiation) and, capacity to chelate ferrous ions (unchanged with irradiation). In conclusion, gamma irradiation reduced the capacity of some antioxidants but preserved the capacity of others. This study showed that one isolated test does not suffice to perform this evaluation reliably, which is a reflection of the diversity and complexity of the effects of irradiation on antioxidant molecules present in different samples.

Phytochemical Evaluation, Antimicrobial Activity, and Determination of Bioactive Components from Leaves of Aegle marmelos

PubMed Central

Mujeeb, Farina; Bajpai, Preeti; Pathak, Neelam

2014-01-01

The therapeutic value of Aegle marmelos Correa (Rutaceae), commonly known as ‘‘Bael,” has been recognized as a component of traditional medication for the treatment of various human ailments. The plant, though, being highly explored, still lacks sufficient evidences for the best variety possessing the highest degree of medicinal values. The present study is focused on phytochemical screening of aqueous and methanolic leaf extracts of 18 varieties/accessions of A. marmelos. The crude extracts of A. marmelos revealed the presence of several biologically active phytochemicals with the highest quantity of alkaloids, flavonoids, and phenols in Pant Aparna variety. The antibacterial efficacy was investigated against pathogenic bacterial strains and the highest inhibitory activity of aqueous extract was obtained against S. epidermidis, whereas methanolic extract was found to be most potent against S. aureus at 40 mg/mL concentration. However, in aqueous : ethanol, the best results were observed against E. aerogenes followed by K. pneumonia and S. epidermidis. The MIC of aqueous and methanol extract of Aegle marmelos ranged from 10 mg/mL to 40 mg/mL whereas in aqueous : ethanol it ranged between 40 mg/mL and 160 mg/mL. The GC-MS analysis revealed the presence of many bioactive compounds such as flavonoids, alcohols, aldehydes, aromatic compounds, fatty acid methyl esters, terpenoids, phenolics, and steroids that can be postulated for antibacterial activity. PMID:24900969

Probing the Hofmeister series beyond water: Specific-ion effects in non-aqueous solvents

NASA Astrophysics Data System (ADS)

Mazzini, Virginia; Liu, Guangming; Craig, Vincent S. J.

2018-06-01

We present an experimental investigation of specific-ion effects in non-aqueous solvents, with the aim of elucidating the role of the solvent in perturbing the fundamental ion-specific trend. The focus is on the anions: CH3COO->F->Cl->Br->I->ClO4 ->SCN- in the solvents water, methanol, formamide, dimethyl sulfoxide (DMSO), and propylene carbonate (PC). Two types of experiments are presented. The first experiment employs the technique of size exclusion chromatography to evaluate the elution times of electrolytes in the different solvents. We observe that the fundamental (Hofmeister) series is observed in water and methanol, whilst the series is reversed in DMSO and PC. No clear series is observed for formamide. The second experiment uses the quartz crystal microbalance technique to follow the ion-induced swelling and collapse of a polyelectrolyte brush. Here the fundamental series is observed in the protic solvents water, methanol, and formamide, and the series is once again reversed in DMSO and PC. These behaviours are not attributed to the protic/aprotic nature of the solvents, but rather to the polarisability of the solvents and are due to the competition between the interaction of ions with the solvent and the surface. A rule of thumb is proposed for ion specificity in non-aqueous solvents. In weakly polarisable solvents, the trends in specific-ion effects will follow those in water, whereas in strongly polarisable solvents the reverse trend will be observed. Solvents of intermediate polarisability will give weak specific-ion effects.

Probing the Hofmeister series beyond water: Specific-ion effects in non-aqueous solvents.

PubMed

Mazzini, Virginia; Liu, Guangming; Craig, Vincent S J

2018-06-14

We present an experimental investigation of specific-ion effects in non-aqueous solvents, with the aim of elucidating the role of the solvent in perturbing the fundamental ion-specific trend. The focus is on the anions: CH 3 COO - >F - >Cl - >Br - >I - >ClO 4 - >SCN - in the solvents water, methanol, formamide, dimethyl sulfoxide (DMSO), and propylene carbonate (PC). Two types of experiments are presented. The first experiment employs the technique of size exclusion chromatography to evaluate the elution times of electrolytes in the different solvents. We observe that the fundamental (Hofmeister) series is observed in water and methanol, whilst the series is reversed in DMSO and PC. No clear series is observed for formamide. The second experiment uses the quartz crystal microbalance technique to follow the ion-induced swelling and collapse of a polyelectrolyte brush. Here the fundamental series is observed in the protic solvents water, methanol, and formamide, and the series is once again reversed in DMSO and PC. These behaviours are not attributed to the protic/aprotic nature of the solvents, but rather to the polarisability of the solvents and are due to the competition between the interaction of ions with the solvent and the surface. A rule of thumb is proposed for ion specificity in non-aqueous solvents. In weakly polarisable solvents, the trends in specific-ion effects will follow those in water, whereas in strongly polarisable solvents the reverse trend will be observed. Solvents of intermediate polarisability will give weak specific-ion effects.

Mild process to design silk scaffolds with reduced β-sheet structure and various topographies at nanometer scale

PubMed Central

Pei, Yazhen; Liu, Xi; Liu, Shanshan; Lu, Qiang; Liu, Jing; Kaplan, David L; Zhu, Hesun

2014-01-01

Three-dimensional (3D) porous silk scaffolds with good biocompatibility and minimal immunogenicity, have promising applications in different tissue regenerations. However, a challenge remains to effectively fabricate their microstructures and mechanical properties to satisfy specific requirements of different tissues. In this study, silk scaffolds were fabricated to form extracellular matrix (ECM) mimetic nanofibrous architecture in a mild process. A slowly increasing concentration process was applied to regulate silk self-assembly into nanofibers in aqueous solution. Then glycerol was blended with the nanofiber solution and induced silk crystallization in lyophilization process, endowing freeze-dried scaffolds water-stability. The glycerol was leached from the scaffolds, leaving similar porous structure at a micrometer scale but different topographies at nanoscale. Compared to previous salt-leached and methanol annealed scaffolds, the present scaffolds showed lower β-sheet content, softer mechanical property, and improved cell growth and differentiation behaviors, implying their promising future as platforms for controlling stem cell fate and soft tissue regeneration. PMID:25463497

A generic method for the determination of acrylamide in thermally processed foods.

PubMed

Gökmen, Vural; Senyuva, Hamide Z

2006-07-07

A generic sample preparation method for the determination of acrylamide in foods was developed. The method entails extraction with methanol, purification with Carrez I and II solutions, evaporation and solvent change to water, and cleanup with Oasis HLB solid-phase extraction (SPE) cartridge. The final extract was analyzed by liquid chromatography-mass spectrometry (LC-MS) for quantitation. The chromatographic separation was performed on ODS-3 column using the isocratic mixture of 0.01 mM acetic acid in 0.2% aqueous solution of formic acid at a flow rate of 0.6 ml/min at 25 degrees C. The recoveries of acrylamide from potato chips, biscuits and coffee ranged between 92.8 and 101.5% with relative standard deviations of 4.1% or less. The limit of detection (LOD) and the limit of quantitation (LOQ) were 2 ng/g and 6 ng/g in the basis of signal to noise ratios of 3:1 and 9:1, respectively.

A Rapid Dialysis Method for Analysis of Artificial Sweeteners in Foods (2nd Report).

PubMed

Tahara, Shoichi; Yamamoto, Sumiyo; Yamajima, Yukiko; Miyakawa, Hiroyuki; Uematsu, Yoko; Monma, Kimio

2017-01-01

Following the previous report, a rapid dialysis method was developed for the extraction and purification of four artificial sweeteners, namely, sodium saccharide (Sa), acesulfame potassium (AK), aspartame (APM), and dulcin (Du), which are present in various foods. The method was evaluated by the addition of 0.02 g/kg of these sweeteners to a cookie sample, in the same manner as in the previous report. Revisions from the previous method were: reduction of the total dialysis volume from 200 to 100 mL, change of tube length from 55 to 50 cm, change of dialysate from 0.01 mol/L hydrochloric aqueous solution containing 10% sodium chloride to 30% methanol solution, and change of dialysis conditions from ambient temperature with occasional shaking to 50℃ with shaking at 160 rpm. As a result of these revisions, the recovery reached 99.3-103.8% with one hour dialysis. The obtained recovery yields were comparable to the recovery yields in the previous method with four hour dialysis.

Dimensional control of supramolecular assemblies of diacetylene-derived peptide gemini amphiphile: from spherical micelles to foamlike networks.

PubMed

Jiang, Hao; Ehlers, Martin; Hu, Xiao-Yu; Zellermann, Elio; Schmuck, Carsten

2018-05-22

Peptide amphiphiles capable of assembling into multidimensional nanostructures have attracted much attention over the past decade due to their potential applications in materials science. Herein, a novel diacetylene-derived peptide gemini amphiphile with a fluorenylmethyloxycarbonyl (Fmoc) group at the N-terminus is reported to hierarchically assemble into spherical micelles, one-dimensional nanorods, two-dimensional foamlike networks and lamellae. Solvent polarity shows a remarkable effect on the self-assembled structures by changing the balance of four weak noncovalent interactions (hydrogen-bonding, π-π stacking, hydrophobic interaction, and electrostatic repulsion). We also show the time-evolution not only from spherical micelles to helical nanofibers in aqueous solution, but also from branched wormlike micelles to foamlike networks in methanol solution. In this work, the presence of the Fmoc group plays a key role in the self-assembly process. This work provides an efficient strategy for precise morphological control, aiding the future development in materials science.

Application and comparison of high performance liquid chromatography and high speed counter-current chromatography in enantioseparation of (±)-2-phenylpropionic acid.

PubMed

Tong, Shengqiang; Zheng, Ye; Yan, Jizhong

2013-03-15

High performance liquid chromatography (HPLC) and high speed counter-current chromatography (HSCCC) were applied and compared in enantioseparation of 2-phenylpropionic acid (2-PPA) when hydroxypropyl-β-cyclodextrin (HP-β-CD) was used as chiral mobile phase additive. For HPLC, the enantioseparation was achieved on ODS C(18) reverse phase column and the mobile phase was 25 mmol L(-1) HP-β-CD aqueous buffer solution (pH 4.0, adjusted with triethylamine): methanol: glacial acetic acid (85:15:0.5 (v/v/v)). For HSCCC, the two-phase solvent system was composed of n-hexane-ethyl acetate-0.1 mol L(-1) phosphate buffer solution pH2.67 (5:5:10 for isocratic elution and 8:2:10 for recycling elution (v/v/v)) added with 0.1 mol L(-1) HP-β-CD. The key parameters, such as a substitution degree of HP-β-CD, the concentration of HP-β-CD, pH value of the aqueous phase and the temperature were optimized for both separation methods. Using the optimum conditions a complete HSCCC enantioseparation of 40 mg of 2-propylpropionic acid in a recycling elution mode gave 15-18 mg of (+)-2-PPA and (-)-2-PPA enantiomers with 95-98% purity and 85-93% recovery. Copyright © 2013 Elsevier B.V. All rights reserved.

Highly conducting and crystalline doubly doped tin oxide films fabricated using a low-cost and simplified spray technique

NASA Astrophysics Data System (ADS)

Ravichandran, K.; Muruganantham, G.; Sakthivel, B.

2009-11-01

Doubly doped (simultaneous doping of antimony and fluorine) tin oxide films (SnO 2:Sb:F) have been fabricated by employing an inexpensive and simplified spray technique using perfume atomizer from aqueous solution of SnCl 2 precursor. The structural studies revealed that the films are highly crystalline in nature with preferential orientation along the (2 0 0) plane. It is found that the size of the crystallites of the doubly doped tin oxide films is larger (69 nm) than that (27 nm) of their undoped counterparts. The dislocation density of the doubly doped film is lesser (2.08×10 14 lines/m 2) when compared with that of the undoped film (13.2×10 14 lines/m 2), indicating the higher degree of crystallinity of the doubly doped films. The SEM images depict that the films are homogeneous and uniform. The optical transmittance in the visible range and the optical band gap of the doubly doped films are 71% and 3.56 eV respectively. The sheet resistance (4.13 Ω/□) attained for the doubly doped film in this study is lower than the values reported for spray deposited fluorine or antimony doped tin oxide films prepared from aqueous solution of SnCl 2 precursor (without using methanol or ethanol).

Thermodynamics of the Sorption of Benzimidazoles on Octadecyl Silica Gel from Water-Methanol Eluents

NASA Astrophysics Data System (ADS)

Shafigulin, R. V.; Bulanova, A. V.

2018-02-01

The standard enthalpy and entropy component of transferring benzimidazoles from water-methanol solutions to surfaces of octadecyl silica gel are determined using reversed-phase high-performance liquid chromatography (RP HPLC). The dependences between the enthalpy and polarizability of the molecules of the studied benzimidazoles, the enthalpy and the entropy factor are studied, and the influence of the quantitative composition of the water-methanol solution on the enthalpy are studied.

Microdroplet fusion mass spectrometry: accelerated kinetics of acid-induced chlorophyll demetallation

PubMed Central

Lee, Jae Kyoo; Nam, Hong Gil; Zare, Richard N.

2017-01-01

Kinetics of acid-induced chlorophyll demetallation was recorded in microdroplets by fusing a stream of microdroplets containing 40 μM chlorophyll a or b dissolved in methanol with a stream of aqueous microdroplets containing 35 mM hydrochloric acid (pH = 1·46). The kinetics of the demetallation of chlorophyll in the fused microdroplets (14 ± 6 μm diameter; 84 ± 18 m s−1 velocity) was recorded by controlling the traveling distance of the fused microdroplets between the fusion region and the inlet of a mass spectrometer. The rate of acid-induced chlorophyll demetallation was about 960 ± 120 times faster in the charged microdroplets compared with that reported in bulk solution. If no voltage was applied to the sprayed microdroplets, then the acceleration factor was about 580 ± 90, suggesting that the applied voltage is not a major factor determining the acceleration. Chlorophyll a was more rapidly demetallated than chlorophyll b by a factor of ~26 in bulk solution and ~5 in charged microdroplets. The demetallation kinetics was second order in the H+ concentration, but the acceleration factor of microdroplets compared with bulk solution appeared to be unchanged in going from pH = 1·3 to 7·0. The water:methanol ratio of the fused microdroplets was varied from 7:3 to 3:7 causing an increase in the reaction rate of chlorophyll a demetallation by 20%. This observation demonstrates that the solvent composition, which has different evaporation rates, does not significantly affect the acceleration. We believe that a major portion of the acceleration can be attributed to confinement effects involving surface reactions rather than either to evaporation of solvents or to the introduction of charges to the microdroplets. PMID:29233214

Microdroplet fusion mass spectrometry: accelerated kinetics of acid-induced chlorophyll demetallation.

PubMed

Lee, Jae Kyoo; Nam, Hong Gil; Zare, Richard N

2017-01-01

Kinetics of acid-induced chlorophyll demetallation was recorded in microdroplets by fusing a stream of microdroplets containing 40 µM chlorophyll a or b dissolved in methanol with a stream of aqueous microdroplets containing 35 mM hydrochloric acid (pH = 1·46). The kinetics of the demetallation of chlorophyll in the fused microdroplets (14 ± 6 µm diameter; 84 ± 18 m s-1 velocity) was recorded by controlling the traveling distance of the fused microdroplets between the fusion region and the inlet of a mass spectrometer. The rate of acid-induced chlorophyll demetallation was about 960 ± 120 times faster in the charged microdroplets compared with that reported in bulk solution. If no voltage was applied to the sprayed microdroplets, then the acceleration factor was about 580 ± 90, suggesting that the applied voltage is not a major factor determining the acceleration. Chlorophyll a was more rapidly demetallated than chlorophyll b by a factor of ~26 in bulk solution and ~5 in charged microdroplets. The demetallation kinetics was second order in the H+ concentration, but the acceleration factor of microdroplets compared with bulk solution appeared to be unchanged in going from pH = 1·3 to 7·0. The water:methanol ratio of the fused microdroplets was varied from 7:3 to 3:7 causing an increase in the reaction rate of chlorophyll a demetallation by 20%. This observation demonstrates that the solvent composition, which has different evaporation rates, does not significantly affect the acceleration. We believe that a major portion of the acceleration can be attributed to confinement effects involving surface reactions rather than either to evaporation of solvents or to the introduction of charges to the microdroplets.

Hybrid quantum chemical studies for the methanol formation reaction assisted by the proton transfer mechanism in supercritical water: CH3Cl+nH2O-->CH3OH+HCl+(n-1)H2O

NASA Astrophysics Data System (ADS)

Hori, T.; Takahashi, H.; Nitta, T.

2003-10-01

The proton transfer along the chain of hydrogen bonds is involved in many chemical reactions in aqueous solution and known to play a decisive role. We have performed the hybrid quantum chemical simulations for the methanol formation reaction catalyzed by the proton transfer mechanism [CH3Cl+nH2O→CH3OH+HCl+(n-1)H2O, n=3] in supercritical water (SCW) to investigate the role of water solvent on the reaction. In the simulation, the electronic state of the chemically active solutes (CH3Cl+3H2O) has been determined quantum mechanically, while the static water solvent has been represented by a classical model. The activation free energy for the water-catalytic reaction in SCW has been found to be 9.6 kcal/mol, which is much lower than that in the gas phase (29.2 kcal/mol). The fractional charge analysis has revealed that the notable charge separation in the solute complex takes place at the transition state (TS) and the resulting huge dipole gives rise to the considerable stabilization of the TS as compared to the reactant. It has been shown that the reaction assisted by the proton transfer mechanism is energetically much favored than the ionic SN2 reaction (CH3Cl+OH-→CH3OH+Cl-, 18.8 kcal/mol). The present calculations suggest that the proton migrations through the chain of hydrogen bonds can be regarded as a probable candidate responsible for the anomalous reactivities observed in SCW.

Hydrostatic pressure effect on PNIPAM cononsolvency in water-methanol solutions.

PubMed

Pica, Andrea; Graziano, Giuseppe

2017-12-01

When methanol is added to water at room temperature and 1atm, poly (N-isopropylacrylamide), PNIPAM, undergoes a coil-to-globule collapse transition. This intriguing phenomenon is called cononsolvency. Spectroscopic measurements have shown that application of high hydrostatic pressure destroys PNIPAM cononsolvency in water-methanol solutions. We have developed a theoretical approach that identifies the decrease in solvent-excluded volume effect as the driving force of PNIPAM collapse on increasing the temperature. The same approach indicates that cononsolvency, at room temperature and P=1atm, is caused by the inability of PNIPAM to make all the attractive energetic interactions that it could be engaged in, due to competition between water and methanol molecules. The present analysis suggests that high hydrostatic pressure destroys cononsolvency because the coil state becomes more compact, and the quantity measuring PNIPAM-solvent attractions increases in magnitude due to the solution density increase, and the ability of small water molecules to substitute methanol molecules on PNIPAM surface. Copyright © 2017 Elsevier B.V. All rights reserved.

Amphiphilic Polysaccharide Block Copolymers for pH-Responsive Micellar Nanoparticles.

PubMed

Breitenbach, Benjamin B; Schmid, Ira; Wich, Peter R

2017-09-11

A full polysaccharide amphiphilic block copolymer was prepared from end group-functionalized dextrans using copper-mediated azide-alkyne click chemistry. Sufficient modification of the reducing end in both blocks was achieved by microwave-enhanced reductive amination in a borate-buffer/methanol solvent system. The combination of a hydrophilic dextran block with a hydrophobic acetalated dextran block results in an amphiphilic structure that turns water-soluble upon acid treatment. The material has a low critical micelle concentration and self-assembles in water to spherical micellar nanoparticles. The formed nanoparticles have a narrow size distribution below 70 nm in diameter and disassemble in slightly acidic conditions. The amphiphilic polysaccharide system shows low toxicity and can stabilize the hydrophobic model drug curcumin in aqueous solutions over extended time periods.

Microbial screening test for lignite degradation. Quarterly progress report No. 4, October-December 1985

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

Yen, T.F.

1985-01-01

Chemical oxidation of lignite by means of hydrogen peroxide - acetic acid was executed. Methanol fractionation of the oxidized product yielded 76.4% methanol solubles, 9.3% methanol insolubles and 11.2% CO/sub 2/. Biodegradation of the methanol fraction by soil bacteria was found to be positive as demonstrated by gel permeation chromatography (GPC). The shift of the average molecular weight throughout biodegradation was estimated to be from 310 g/mole, to 243 g/mole, zero day and four weeks respectively. Biodegradation of lignitic substrates, benzene - methanol fraction (A - 1), aqueous alkaline fraction (A - 2), clean lignite residue (A - 3), rawmore » lignite, and methanol soluble fraction after oxidation, by means of oil - field soil bacteria and Polyporus versicolor ATCC 12679 was attempted. All previous mentioned lignitic substrates yielded positive results for oil-field soil bacteria, while A - 2 fraction and raw lignite yielded positive results for P. versicolor. Unidentified fungi strains, N 1, L 1, and L 2 were also tested on lignitic substrates. Mild growth was observed in these cases.« less

Molecular mechanism of the adsorption process of an iodide anion into liquid-vapor interfaces of water-methanol mixtures

NASA Astrophysics Data System (ADS)

Annapureddy, Harsha V. R.; Dang, Liem X.

2012-12-01

To enhance our understanding of the molecular mechanism of ion adsorption to the interface of mixtures, we systematically carried out a free energy calculations study involving the transport of an iodide anion across the interface of a water-methanol mixture. Many body affects are taken into account to describe the interactions among the species. The surface propensities of I- at interfaces of pure water and methanol are well understood. In contrast, detailed knowledge of the molecular level adsorption process of I- at aqueous mixture interfaces has not been reported. In this paper, we explore how this phenomenon will be affected for mixed solvents with varying compositions of water and methanol. Our potential of mean force study as function of varying compositions indicated that I- adsorption free energies decrease from pure water to pure methanol but not linearly with the concentration of methanol. We analyze the computed density profiles and hydration numbers as a function of concentrations and ion positions with respect to the interface to further explain the observed phenomenon.

A sulphated flavone glycoside from Livistona australis and its antioxidant and cytotoxic activity.

PubMed

Kassem, Mona E S; Shoela, Soha; Marzouk, Mona M; Sleem, Amany A

2012-01-01

A new flavone glycoside tricin 7-O-β-glucopyranoside-2″-sulphate sodium salt along with 14 known flavonoid compounds were isolated and identified from the aqueous methanol extract of Livistona australis leaves. Their structures were established on the basis of extensive NMR (¹H, ¹³C, HSQC and H-H COSY) and ESIMS data. Antioxidant and cytotoxicity properties of the methanol extract of the leaves as well as the new compound were investigated.

Alcohol-induced drying of carbon nanotubes and its implications for alcohol/water separation: a molecular dynamics study.

PubMed

Tian, Xingling; Yang, Zaixing; Zhou, Bo; Xiu, Peng; Tu, Yusong

2013-05-28

Alcohols are important products in chemical industry, but separating them from their aqueous solutions is very difficult due to the hydrophilic nature of alcohols. Based on molecular dynamics simulations, we observe a striking nanoscale drying phenomenon and suggest an energy-saving and efficient approach toward alcohol∕water separation by using single-walled carbon nanotubes (SWNTs). We use various common linear alcohols including C1-C6 1-alcohols and glycerol for demonstration (the phenol is also used as comparison). Our simulations show that when SWNTs are immersed in aqueous alcohols solutions, although the alcohols concentration is low (1 M), all kinds of alcohols can induce dehydration (drying) of nanotubes and accumulate inside wide [(13, 13)] and narrow [(6, 6) or (7, 7)] SWNTs. In particular, most kinds of alcohols inside the narrow SWNTs form nearly uniform 1D molecular wires. Detailed energetic analyses reveal that the preferential adsorption of alcohols over water inside nanotubes is attributed to the stronger dispersion interactions of alcohols with SWNTs than water. Interestingly, we find that for the wide SWNT, the selectivity for 1-alcohols increases with the number of alcohol's carbon atoms (Ncarbon) and exhibits an exponential law with respect to Ncarbon for C1-C5 1-alcohols; for narrow SWNTs, the selectivity for 1-alcohols is very high for methanol, ethanol, and propanol, and reaches a maximum when Ncarbon = 3. The underlying physical mechanisms and the implications of these observations for alcohol∕water separation are discussed. Our findings provide the possibility for efficient dehydration of aqueous alcohols (and other hydrophilic organic molecules) by using SWNT bundles∕membranes.

Alcohol-induced drying of carbon nanotubes and its implications for alcohol/water separation: A molecular dynamics study

NASA Astrophysics Data System (ADS)

Tian, Xingling; Yang, Zaixing; Zhou, Bo; Xiu, Peng; Tu, Yusong

2013-05-01

Alcohols are important products in chemical industry, but separating them from their aqueous solutions is very difficult due to the hydrophilic nature of alcohols. Based on molecular dynamics simulations, we observe a striking nanoscale drying phenomenon and suggest an energy-saving and efficient approach toward alcohol/water separation by using single-walled carbon nanotubes (SWNTs). We use various common linear alcohols including C1-C6 1-alcohols and glycerol for demonstration (the phenol is also used as comparison). Our simulations show that when SWNTs are immersed in aqueous alcohols solutions, although the alcohols concentration is low (1 M), all kinds of alcohols can induce dehydration (drying) of nanotubes and accumulate inside wide [(13, 13)] and narrow [(6, 6) or (7, 7)] SWNTs. In particular, most kinds of alcohols inside the narrow SWNTs form nearly uniform 1D molecular wires. Detailed energetic analyses reveal that the preferential adsorption of alcohols over water inside nanotubes is attributed to the stronger dispersion interactions of alcohols with SWNTs than water. Interestingly, we find that for the wide SWNT, the selectivity for 1-alcohols increases with the number of alcohol's carbon atoms (Ncarbon) and exhibits an exponential law with respect to Ncarbon for C1-C5 1-alcohols; for narrow SWNTs, the selectivity for 1-alcohols is very high for methanol, ethanol, and propanol, and reaches a maximum when Ncarbon = 3. The underlying physical mechanisms and the implications of these observations for alcohol/water separation are discussed. Our findings provide the possibility for efficient dehydration of aqueous alcohols (and other hydrophilic organic molecules) by using SWNT bundles/membranes.

Ultra-preconcentration and determination of selected pharmaceutical and personal care products in different water matrices by solid-phase extraction combined with dispersive liquid-liquid microextraction prior to ultra high pressure liquid chromatography tandem mass spectrometry analysis.

PubMed

Celano, Rita; Piccinelli, Anna Lisa; Campone, Luca; Rastrelli, Luca

2014-08-15

Pharmaceutical and personal care products (PPCPs) are one of the most important classes of emerging contaminants. The potential of ecological and environmental impacts associated with PPCPs are of particular concern because they continually penetrate the aquatic environment. This work describes a novel ultra-preconcentration technique for the rapid and highly sensitive analysis of selected PPCPs in environmental water matrices at ppt levels. Selected PPCPs were rapidly extracted and concentrated from large volumes of aqueous solutions (500 and 250mL) by solid-phase extraction combined with dispersive liquid-liquid microextraction (SPE-DLLME) and then analyzed using UHPLC-MS/MS. Experimental parameters were carefully investigated and optimized to achieve the best SPE-DLLME efficiency and higher enrichment factors. The best results were obtained using the ternary mixture acetonitrile/methanol/dichloromethane 3:3:4, v/v/v, both as SPE eluent and DLLME extractant/dispersive mixture. DLLME aqueous solution (5% NaCl, 10mgL(-1) TBAB) was also modified to improve the extraction efficiency of more hydrophilic PPCPs. Under the optimal conditions, an exhaustive extraction for most of the investigated analytes (recoveries >70%), with a precision (RSD <10%) and very high enrichment factors were attained for different aqueous matrices (drinking, sea, river and wastewater). Method detection and quantification limits were at very low ppt levels and below 1 and 3ngL(-1), respectively, for 15 of selected PPCPs. The proposed analytical procedure offers numerous advantages such as the simplicity of operation, rapidity, a high enrichment factor and sensitivity. So it is suitable for monitoring and studies of occurrence of PPCPs in different environmental compartments. Copyright © 2014 Elsevier B.V. All rights reserved.

Chemical Disequilibria and Sources of Gibbs Free Energy Inside Enceladus

NASA Astrophysics Data System (ADS)

Zolotov, M. Y.

2010-12-01

Non-photosynthetic organisms use chemical disequilibria in the environment to gain metabolic energy from enzyme catalyzed oxidation-reduction (redox) reactions. The presence of carbon dioxide, ammonia, formaldehyde, methanol, methane and other hydrocarbons in the eruptive plume of Enceladus [1] implies diverse redox disequilibria in the interior. In the history of the moon, redox disequilibria could have been activated through melting of a volatile-rich ice and following water-rock-organic interactions. Previous and/or present aqueous processes are consistent with the detection of NaCl and Na2CO3/NaHCO3-bearing grains emitted from Enceladus [2]. A low K/Na ratio in the grains [2] and a low upper limit for N2 in the plume [3] indicate low temperature (possibly < 273 K) of aqueous processes. Although many of the energetically favorable redox reactions are sluggish at low temperature, they could be catalyzed by enzymes if organisms were (are) present. The redox conditions in aqueous systems and amounts of available Gibbs free energy should have been affected by the production, consumption and escape of hydrogen. Aqueous oxidation of minerals (Fe-Ni metal, Fe-Ni phosphides, etc.) accreted on Enceladus should have led to H2 production, which is consistent with H2 detection in the plume [1]. Numerical evaluations based on concentrations of plume gases [1] reveal sufficient energy sources available to support metabolically diverse life at a wide range of activities (a) of dissolved H2 (log aH2 from 0 to -10). Formaldehyde, carbon dioxide [c.f. 4], HCN (if it is present), methanol, acetylene and other hydrocarbons have the potential to react with H2 to form methane. Aqueous hydrogenations of acetylene, HCN and formaldehyde to produce methanol are energetically favorable as well. Both favorable hydrogenation and hydration of HCN lead to formation of ammonia. Condensed organic species could also participate in redox reactions. Methane and ammonia are the final products of these putative redox transformations. Sulfates may have not formed in cold and/or short-term aqueous environments with a limited H2 escape. In contrast to Earth, Mars and Europa, the moon may have no (or very limited [4]) potential for sulfate reduction. Despite nutrient (C, N, P and S) and metal (e.g. Fe, Ni) rich environments and multiple sources of Gibbs free energy during aqueous episode(s), putative life on Enceladus [4] would have adapted to survive in low water activity alkaline brines rich in ammonia, methanol and organic liquids at temperature >150-170 K. The comet-like abundances of major plume gases and apparent redox disequilibria in aquatic systems are consistent with a minimal influence of aqueous processes on endogenic chemical reactions and may indicate abiotic interior. Alternatively, plume gases may represent never melted primordial parcels of the icy shell, while the deeper interior could contain altered species transformed in abiotic and/or biological processes. Refs: [1] Waite J. et al. (2009) Nature 460, 487-490. [2] Postberg F. et al. (2009) Nature 459, 1098-1101. [3] Hansen C. et al. (2010) 38th COSPAR Sci. Assembly. [4] McKay C. et al. (2008) Astrobiology 8, 909-919.

Study of complexation process between 4'-nitrobenzo-15-crown-5 and yttrium(III) cation in binary mixed non-aqueous solvents using conductometric method

NASA Astrophysics Data System (ADS)

Habibi, N.; Rounaghi, G. H.; Mohajeri, M.

2012-12-01

The complexation reaction of macrocyclic ligand (4'-nitrobenzo-15C5) with Y3+ cation was studied in acetonitrile-methanol (AN-MeOH), acetonitrile-ethanol (AN-EtOH), acetonitrile-dimethylformamide (AN-DMF) and ethylacetate-methanol (EtOAc-MeOH) binary mixtures at different temperatures using conductometry method. The conductivity data show that in all solvent systems, the stoichiometry of the complex formed between 4'-nitrobenzo-15C5 and Y3+ cation is 1: 1 (ML). The stability order of (4'-nitrobenzo-15C5). Y3+ complex in pure non-aqueous solvents at 25°C was found to be: EtOAc > EtOH > AN ≈ DMF > MeOH, and in the case of most compositions of the binary mixed solvents at 25°C it was: AN≈MeOH ≈ AN-EtOH > AN-DMF > EtOAc-MeOH. But the results indicate that the sequence of the stability of the complex in the binary mixed solutions changes with temperature. A non-linear behavior was observed for changes of log K f of (4'-nitrobenzo-15C5 · Y3+) complex versus the composition of the binary mixed solvents, which was explained in terms of solvent-solvent interactions and also the hetero-selective solvation of the species involved in the complexation reaction. The values of thermodynamic parameters (Δ H {c/ℴ} and Δ S {c/ℴ}) for formation of the complex were obtained from temperature dependent of the stability constant using the van't Hoff plots. The results represent that in most cases, the complex is both enthalpy and entropy stabilized and the values and also the sign of thermodynamic parameters are influenced by the nature and composition of the mixed solvents.

Antiamoebic Activity of Petiveria alliacea Leaves and Their Main Component, Isoarborinol.

PubMed

Zavala Ocampo, Lizeth M; Aguirre-HernÁndez, Eva; Pérez-HernÁndez, Nury; Rivera, Gildardo; Marchat, Laurence A; Ramírez-Moreno, Esther

2017-08-28

Petiveria alliacea L. (Phytolacaceae) is a medicinal plant with a broad range of traditional therapeutic properties, including the treatment of dysentery and intestinal infections caused by protozoan parasites. However, its effects against Entamoeba histolytica have not been reported yet. We investigated the antiamoebic activity present in the leaves of P. alliacea Antiamoebic activity was evaluated in methanolic and aqueous extracts, as well as in the hexanic, methanolic, and EtOAc fractions. The P. alliacea methanolic extract showed a better antiamoebic activity than the aqueous extract with an IC 50 = 0.51 mg/ml. Likewise, the hexanic fraction was the most effective fraction, showing a dose-dependent activity against E. histolytica , with an IC 50 = 0.68 mg/ml. Hexanic subfraction 12-19 showed the highest antiamoebic activity at 0.8 mg/ml, producing 74.3% growth inhibition without any toxicity in mammal cells. A major component in subfraction 12-19 was identified as isoarborinol, which produced 51.4% E. histolytica growth inhibition at 0.05 mg/ml without affecting mammal cells. The P. alliacea leaf extract has antiamoebic activity that can be attributed to a major metabolite known as isoarborinol.

Focused microwave-assisted solvent extraction and HPLC determination of effective constituents in Eucommia ulmodies Oliv. (E. ulmodies).

PubMed

Li, Hui; Chen, Bo; Zhang, Zhaohui; Yao, Shouzhuo

2004-06-17

A new focused microwave-assisted solvent extraction method using water as solvent has been developed for leaching geniposidic and chlorogenic acids from Eucommia ulmodies Oliv. The extraction procedures were optimized using a two indexes orthogonal experimental design and graphical analysis, by varying irradiation time, solvent volume, solvent composition and microwave power. The optimum extraction conditions were obtained: for geniposidic acid, 50% micorwave power, 40s irradiation, and 80% (v/v) aqueous methanol as extraction solvent (20mlg(-1) sample); and for chlorogenic acid, 50% micorwave power, 30s irradiation, and 20% aqueous methanol (20mlg(-1) sample). The composition of the extraction solvent was optimized and can be directly used as the mobile phase in the HPLC separation. Quantification of organic acids was done by HPLC at room temperature using Spherigel C(18) chromatographic column (250 mm x4.6 mm , i.d. 5mum), the methanol:water:acetic acid (20:80:1.0, v/v) mobile phase and UV detection at 240nm. The R.S.D. of the extraction process for geniposidic and chlorogenic acid were 3.8 and 4.1%, respectively.

Determination of mycotoxins produced by Fusarium isolates from banana fruits by capillary gas chromatography and high-performance liquid chromatography.

PubMed

Jiménez, M; Mateo, R

1997-08-22

A method of analysis for trichothecenes (nivalenol, deoxynivalenol, 3- and 15-acetyldeoxynivalenol, diacetoxyscirpenol, neosolaniol, T-2 tetraol, T-2 and HT-2 toxins), zearalenone and zearalenols, and another method for determination of fumonisin B1 are described and applied to cultures of Fusarium isolated from bananas. Both methods were adapted from different techniques of extraction, clean-up and determination of these mycotoxins. The first method involves extraction with methanol-1% aqueous sodium chloride, clean-up of extracts by partition with hexane and dichloromethane, additional solid reversed-phase clean-up and analysis of two eluates by both high-performance liquid chromatography with ultraviolet detection and capillary gas chromatography. The method for fumonisin B1 implies extraction with aqueous methanol, concentration, clean-up with water and methanol on Amberlite XAD-2 column, formation of a fluorescent 4-fluoro-7-nitrobenzofurazan derivative and analysis by high-performance liquid chromatography with fluorescence detection. Both procedures give good limits of detection and recoveries, and are considered suitable for the detection and quantification of the studied toxins in corn and rice cultures of Fusarium spp. isolated from banana fruits.

Screening of Bunium bulbocastanum for antibacterial, antifungal, phytotoxic and haemagglutination activities.

PubMed

Khan, Ibrar; Ahmad, Haroon; Ali, Nasir; Ahmad, Bashir; Tanoli, Hamid

2013-07-01

The current study was aimed at screening the Bunium bulbocastanum for its antibacterial, antifungal, phytotoxic and haemagglutination activities.The crude methanolic extract and n-hexane fraction showed significant (89%) and good activity (61%) against Staphylococcus aureus while the CHCl3fraction was moderately active against S.aureus (53%). Moderate activitywas shown by the EtOAc fraction against B. subtilis (44%). This fraction was inactive against P.aerogenosa and S.aureus. The aqueous fraction showed significant activity against B. subtilis (85%), moderate against S.aureus(34 %) and E. coli (33%)and low activity against P.aerogenosa(29%). Our results for antifungal assay indicated that all the test samples were inactive against all the test fungi. The phytotoxic activity of the plant at 1000 and 100 μg/ml was: crude methanolic extract (53.33 and 46.66%), n-hexane (46.66 and 26.66%), CHCl3 (20 and 6.66%), EtOAc (46.66 and 26.66%) and aqueous (40 and 33.33%). All the test samples (crude methanolic extract and fractions) of B. bulbocastanum were unable to agglutinate RBCs of the human blood indicating that this species lack phytolectins.

Metabolite extraction from adherently growing mammalian cells for metabolomics studies: optimization of harvesting and extraction protocols.

PubMed

Dettmer, Katja; Nürnberger, Nadine; Kaspar, Hannelore; Gruber, Michael A; Almstetter, Martin F; Oefner, Peter J

2011-01-01

Trypsin/ethylenediaminetetraacetic acid (EDTA) treatment and cell scraping in a buffer solution were compared for harvesting adherently growing mammalian SW480 cells for metabolomics studies. In addition, direct scraping with a solvent was tested. Trypsinated and scraped cell pellets were extracted using seven different extraction protocols including pure methanol, methanol/water, pure acetone, acetone/water, methanol/chloroform/water, methanol/isopropanol/water, and acid-base methanol. The extracts were analyzed by GC-MS after methoximation/silylation and derivatization with propyl chloroformate, respectively. The metabolic fingerprints were compared and 25 selected metabolites including amino acids and intermediates of energy metabolism were quantitatively determined. Moreover, the influence of freeze/thaw cycles, ultrasonication and homogenization using ceramic beads on extraction yield was tested. Pure acetone yielded the lowest extraction efficiency while methanol, methanol/water, methanol/isopropanol/water, and acid-base methanol recovered similar metabolite amounts with good reproducibility. Based on overall performance, methanol/water was chosen as a suitable extraction solvent. Repeated freeze/thaw cycles, ultrasonication and homogenization did not improve overall metabolite yield of the methanol/water extraction. Trypsin/EDTA treatment caused substantial metabolite leakage proving it inadequate for metabolomics studies. Gentle scraping of the cells in a buffer solution and subsequent extraction with methanol/water resulted on average in a sevenfold lower recovery of quantified metabolites compared with direct scraping using methanol/water, making the latter one the method of choice to harvest and extract metabolites from adherently growing mammalian SW480 cells.

Curative effect of Amorphophallus paeoniifolius tuber on experimental hemorrhoids in rats.

PubMed

Dey, Yadu Nandan; Wanjari, Manish M; Kumar, Dharmendra; Lomash, Vinay; Jadhav, Ankush D

2016-11-04

Amorphophallus paeoniifolius (Dennst.) Nicolson (Family- Araceae) is a crop of south East Asian origin. In India, its tuber is widely used in ethnomedicinal practices by different tribes for the treatment of piles (hemorrhoids). The present study evaluated the effect of methanolic and aqueous extract of Amorphophallus paeoniifolius tuber on croton oil induced hemorrhoids in rats. The methanolic extract was standardized with the major phenolic compound, betulinic acid, by HPLC. The hemorrhoids were induced by applying 6% croton oil preparation in the ano-rectal region. Rats were orally administered methanolic and aqueous extract at doses of 250 and 500mg/kg, each for 7 days. Pilex (200mg/kg) was used as reference anti-hemorrhoidal drug. Hemorrhoids were assessed on eighth day by measuring hemorrhoidal and biochemical parameters along with histology of ano-rectal tissue. Croton oil application caused induction of hemorrhoids as indicated by significant (p<0.001) increase in plasma exudation of Evans blue in ano-rectal tissue, macroscopic severity score and ano-rectal coefficient as compared to normal rats. It significantly (p<0.001) elevated lactate dehydrogenase and cytokines (TNF-α and IL-6) levels in serum and increased myeloperoxidase activity and lipid peroxidation in ano-rectal tissue along with marked histological damage as compared to normal rats. Treatment with tuber extracts and pilex significantly (p<0.05-p<0.001) ameliorated Evans blue exudation, hemorrhoidal parameters and other biochemical parameters with attenuation of tissue damage compared to hemorrhoid control rats. The results indicate that tuber extracts exhibited curative action on hemorrhoids. The aqueous extract showed more pronounced effect than methanolic extract. The effects may be attributed to anti-inflammatory and antioxidant properties. Results indicate that tuber of Amorphophallus paeoniifolius exhibited curative action on hemorrhoids through anti-inflammatory and antioxidant properties. The study validates the ethnomedicinal use of tuber in hemorrhoids and implicates its therapeutic potential as an anti-hemorrhoidal agent. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Antioxidant Activity and ROS-Dependent Apoptotic Effect of Scurrula ferruginea (Jack) Danser Methanol Extract in Human Breast Cancer Cell MDA-MB-231

PubMed Central

Marvibaigi, Mohsen; Amini, Neda; Supriyanto, Eko; Abdul Majid, Fadzilah Adibah; Kumar Jaganathan, Saravana; Jamil, Shajarahtunnur; Hamzehalipour Almaki, Javad; Nasiri, Rozita

2016-01-01

Scurrula ferruginea (Jack) Danser is one of the mistletoe species belonging to Loranthaceae family, which grows on the branches of many deciduous trees in tropical countries. This study evaluated the antioxidant activities of S. ferruginea extracts. The cytotoxic activity of the selected extracts, which showed potent antioxidant activities, and high phenolic and flavonoid contents, were investigated in human breast cancer cell line (MDA-MB-231) and non-cancer human skin fibroblast cells (HSF-1184). The activities and characteristics varied depending on the different parts of S. ferruginea, solvent polarity, and concentrations of extracts. The stem methanol extract showed the highest amount of both phenolic (273.51 ± 4.84 mg gallic acid/g extract) and flavonoid contents (163.41 ± 4.62 mg catechin/g extract) and strong DPPH• radical scavenging (IC50 = 27.81 μg/mL) and metal chelation activity (IC50 = 80.20 μg/mL). The stem aqueous extract showed the highest ABTS•+ scavenging ability. The stem methanol and aqueous extracts exhibited dose-dependent cytotoxic activity against MDA-MB-231 cells with IC50 of 19.27 and 50.35 μg/mL, respectively. Furthermore, the extracts inhibited the migration and colony formation of MDA-MB-231 cells in a concentration-dependent manner. Morphological observations revealed hallmark properties of apoptosis in treated cells. The methanol extract induced an increase in ROS generation and mitochondrial depolarization in MDA-MB-231 cells, suggesting its potent apoptotic activity. The present study demonstrated that the S. ferruginea methanol extract mediated MDA-MB-231 cell growth inhibition via induction of apoptosis which was confirmed by Western blot analysis. It may be a potential anticancer agent; however, its in vivo anticancer activity needs to be investigated. PMID:27410459

Antihyperlipidemic, Antioxidant and Cytotoxic Activities of Methanolic and Aqueous Extracts of Different Parts of Star Fruit.

PubMed

Saghir, Sultan A M; Sadikun, Amirin; Al-Suede, Fouad S R; Majid, Amin M S A; Murugaiyah, Vikneswaran

Star fruit (Averrhoa carambola) is a well-known plant in Malaysia which bears a great significance in traditional medicine. This study aimed to evaluate the antihyperlipidemic effect, antioxidant potential and cytotoxicity of aqueous and methanolic extracts of ripe and unripe fruits, leaves and stem of A. carambola. Antihyperlipidemic activity was assessed in poloxamer-407 (P-407) induced acute hyperlipidemic rat's model. The antioxidant activity was assessed in vitro using 2, 2'-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical scavenging, 1-diphenyl-2-dipicrylhydrazyl radical scavenging (DPPH) and ferric reducing antioxidant power (FRAP) assays. In addition, cytotoxicity of A. carambola extracts was assessed using MTS assay on four leukemic cell lines (human colon cancer, human promyeloid leukemia, erythroid leukemia, acute myeloid leukemia) and one normal cell (human umbilical vein endothelial cells). Methanolic extract of leaves had the most potent antihyperlipidemic activity in P-407 model, whereby it significantly reduced serum levels of total cholesterol (P<0.01), triglycerides (P<0.01), low-density lipoprotein (P<0.05), verylow- density lipoprotein (P<0.01) and atherogenic index (P<0.01). On the other hand, methanolic extracts of A. carambola stem and leaves showed the strongest antioxidant activity. Total phenolic and flavonoid contents of the extracts exhibited significant correlations with antioxidant but not with antihyperlipidemic activities. All plant parts showed no cytotoxic effect on the selected cancer or normal cell lines. Antihyperlipidemic activity of different parts of A. carambola is greatly affected by extraction solvents used. Methanolic extract of A. carambola leaves exhibited higher antihyperlipidemic and antioxidant potentials compared to other parts of the plant.

Retention equations of nonionic organic chemicals in soil column chromatography with methanol-water eluents.

PubMed

Xu, Feng; Liang, Xinmiao; Lin, Bingcheng

2002-01-01

Research efforts dealing with chemical transportation in soils are needed to prevent damage to ground water. Methanol-containing solvents can increase the translocation of nonionic organic chemicals (NOCs). In this study, a general log-linear retention equation, log k' = log k'w - Sphi (Eq. [1]), was developed to describe the mobilities of NOCs in soil column chromatography (SCC). The term phi denotes the volume fraction of methanol in eluent, k' is the capacity factor of a solute at a certain phi value, and log k'w and -S are the intercept and slope of the log k' vs. phi plot. Two reference soils (GSE 17204 and GSE 17205) were used as packing materials, and were eluted by isocratic methanol-water mixtures. A model of linear solvation energy relationships (LSER) was applied to analyze the k' from molecular interactions. The most important factor determining the transportation was found to be the solute hydrophobic partition in soils, and the second-most important factor was the solute hydrogen-bond basicity (hydrogen-bond accepting ability), while the less important factor was the solute dipolarity-polarizability. The solute hydrogen-bond acidity (hydrogen-bond donating ability) was statistically unimportant and deletable. From the LSER model, one could also obtain Eq. [1]. The experimental k' data of 121 NOCs can be accurately explained by Eq. [1]. The equation is promising to estimate the solute mobility in pure water by extrapolating from lower-capacity factors obtained in methanol-water mixed eluents.

Application of acetone acetals as water scavengers and derivatization agents prior to the gas chromatographic analysis of polar residual solvents in aqueous samples.

PubMed

van Boxtel, Niels; Wolfs, Kris; Van Schepdael, Ann; Adams, Erwin

2015-12-18

The sensitivity of gas chromatography (GC) combined with the full evaporation technique (FET) for the analysis of aqueous samples is limited due to the maximum tolerable sample volume in a headspace vial. Using an acetone acetal as water scavenger prior to FET-GC analysis proved to be a useful and versatile tool for the analysis of high boiling analytes in aqueous samples. 2,2-Dimethoxypropane (DMP) was used in this case resulting in methanol and acetone as reaction products with water. These solvents are relatively volatile and were easily removed by evaporation enabling sample enrichment leading to 10-fold improvement in sensitivity compared to the standard 10μL FET sample volumes for a selection of typical high boiling polar residual solvents in water. This could be improved even further if more sample is used. The method was applied for the determination of residual NMP in an aqueous solution of a cefotaxime analogue and proved to be considerably better than conventional static headspace (sHS) and the standard FET approach. The methodology was also applied to determine trace amounts of ethylene glycol (EG) in aqueous samples like contact lens fluids, where scavenging of the water would avoid laborious extraction prior to derivatization. During this experiment it was revealed that DMP reacts quantitatively with EG to form 2,2-dimethyl-1,3-dioxolane (2,2-DD) under the proposed reaction conditions. The relatively high volatility (bp 93°C) of 2,2-DD makes it possible to perform analysis of EG using the sHS methodology making additional derivatization reactions superfluous. Copyright © 2015 Elsevier B.V. All rights reserved.

Cytotoxicity and antiviral activities of Asplenium nidus, Phaleria macrocarpa and Eleusine indica

NASA Astrophysics Data System (ADS)

Tahir, Mariya Mohd; Ibrahim, Nazlina; Yaacob, Wan Ahmad

2014-09-01

Three local medicinal plants namely Asplenium nidus (langsuyar), Eleusine indica (sambau) and Phaleria macrocarpa (mahkota dewa) were screened for the cytotoxicity and antiviral activities. Six plant extracts were prepared including the aqueous and methanol extracts from A. nidus leaf and root, aqueous extract from dried whole plant of E. indica and methanol extract from P. macrocarpa fruits. Cytotoxicity screening in Vero cell line by MTT assay showed that the CC50 values ranged from 15 to 60 mg/mL thus indicating the safety of the extracts even at high concentrations. Antiviral properties of the plant extracts were determined by plaque reduction assay. The EC50 concentrations were between 3.2 to 47 mg/mL. The selectivity indices (SI = CC50/EC50) of each tested extracts ranged from 4.3 to 63.25 indicating the usefulness of the extracts as potential antiviral agents.

Electrochemical Corey–Winter reaction. Reduction of thiocarbonates in aqueous methanol media and application to the synthesis of a naturally occurring α-pyrone

PubMed Central

López-López, Ernesto Emmanuel; Pérez-Bautista, José Alvano

2018-01-01

An electrochemical version of the Corey–Winter reaction was developed giving excellent results in aqueous methanol media (MeOH/H2O (80:20) with AcOH/AcONa buffer 0.5 M as supporting electrolyte), using a reticulated vitreous carbon as cathode in a divided cell. The electrochemical version is much more environmentally friendly than the classical reaction, where a large excess of trialkyl phosphite as reducing agent and high temperatures are required. Thus, cathodic reduction at room temperature of two cyclic thiocarbonates (−1.2 to −1.4 V vs Ag/AgCl) afforded the corresponding alkenes, trans-6-(pent-1-enyl)-α-pyrone and trans-6-(pent-1,4-dienyl)-α-pyrone, which are naturally occurring metabolites isolated from Trichoderma viride and Penicillium, in high chemical yield and with excellent stereo selectivity. PMID:29623116

Electrochemical Corey-Winter reaction. Reduction of thiocarbonates in aqueous methanol media and application to the synthesis of a naturally occurring α-pyrone.

PubMed

López-López, Ernesto Emmanuel; Pérez-Bautista, José Alvano; Sartillo-Piscil, Fernando; Frontana-Uribe, Bernardo A

2018-01-01

An electrochemical version of the Corey-Winter reaction was developed giving excellent results in aqueous methanol media (MeOH/H 2 O (80:20) with AcOH/AcONa buffer 0.5 M as supporting electrolyte), using a reticulated vitreous carbon as cathode in a divided cell. The electrochemical version is much more environmentally friendly than the classical reaction, where a large excess of trialkyl phosphite as reducing agent and high temperatures are required. Thus, cathodic reduction at room temperature of two cyclic thiocarbonates (-1.2 to -1.4 V vs Ag/AgCl) afforded the corresponding alkenes, trans -6-(pent-1-enyl)-α-pyrone and trans -6-(pent-1,4-dienyl)-α-pyrone, which are naturally occurring metabolites isolated from Trichoderma viride and Penicillium , in high chemical yield and with excellent stereo selectivity.

Isolation and identification of arctiin and arctigenin in leaves of burdock (Arctium lappa L.) by polyamide column chromatography in combination with HPLC-ESI/MS.

PubMed

Liu, Shiming; Chen, Kaoshan; Schliemann, Willibald; Strack, Dieter

2005-01-01

A simple method involving polyamide column chromatography in combination with HPLC-PAD and HPLC-ESI/MS for isolating and identifying two kinds of lignans, arctiin and arctigenin, in the leaves of burdock (Arctium lappa L.) has been established. After extraction of burdock leaves with 80% methanol, the aqueous phase of crude extracts was partitioned between water and chloroform and the aqueous phase was fractionated on a polyamide glass column. The fraction, eluting with 100% methanol, was concentrated and gave a white precipitate at 4 degrees C from which two main compounds were purified by semi-preparative HPLC. In comparison with the UV and ESI-MS spectra and the HPLC retention time of authentic standards, the compounds were determined to be arctiin and arctigenin. The extraction/separation technique was validated using an internal standard method.

SOLVENT EXTRACTION PROCESS

DOEpatents

Jonke, A.A.

1957-10-01

In improved solvent extraction process is described for the extraction of metal values from highly dilute aqueous solutions. The process comprises contacting an aqueous solution with an organic substantially water-immiscible solvent, whereby metal values are taken up by a solvent extract phase; scrubbing the solvent extract phase with an aqueous scrubbing solution; separating an aqueous solution from the scrubbed solvent extract phase; and contacting the scrubbed solvent phase with an aqueous medium whereby the extracted metal values are removed from the solvent phase and taken up by said medium to form a strip solution containing said metal values, the aqueous scrubbing solution being a mixture of strip solution and an aqueous solution which contains mineral acids anions and is free of the metal values. The process is particularly effective for purifying uranium, where one starts with impure aqueous uranyl nitrate, extracts with tributyl phosphate dissolved in carbon tetrachloride, scrubs with aqueous nitric acid and employs water to strip the uranium from the scrubbed organic phase.

In vitro antioxidant and, α-glucosidase inhibitory activities and comprehensive metabolite profiling of methanol extract and its fractions from Clinacanthus nutans.

PubMed

Alam, Md Ariful; Zaidul, I S M; Ghafoor, Kashif; Sahena, F; Hakim, M A; Rafii, M Y; Abir, H M; Bostanudin, M F; Perumal, V; Khatib, A

2017-03-31

This study was aimed to evaluate antioxidant and α-glucosidase inhibitory activity, with a subsequent analysis of total phenolic and total flavonoid content of methanol extract and its derived fractions from Clinacanthus nutans accompanied by comprehensive phytochemical profiling. Liquid-liquid partition chromatography was used to separate methanolic extract to get hexane, ethyl acetate, butanol and residual aqueous fractions. The total antioxidant activity was determined by 2,2-diphenyl-1-picrylhydrazy (DPPH) radical scavenging and ferric reducing antioxidant power assay (FRAP). The antidiabetic activity of methanol extract and its consequent fractions were examined by α-glucosidase inhibitory bioassay. The chemical profiling was carried out by gas chromatography coupled with quadrupole time-of-flight mass spectrometry (GC Q-TOF MS). The total yield for methanol extraction was (12.63 ± 0.98) % (w/w) and highest fractionated value found for residual aqueous (52.25 ± 1.01) % (w/w) as compared to the other fractions. Significant DPPH free radical scavenging activity was found for methanolic extract (63.07 ± 0.11) % and (79.98 ± 0.31) % for ethyl acetate fraction among all the fractions evaluated. Methanol extract was the most prominent in case of FRAP (141.89 ± 0.87 μg AAE/g) whereas most effective reducing power observed in ethyl acetate fraction (133.6 ± 0.2987 μg AAE/g). The results also indicated a substantial α-glucosidase inhibitory activity for butanol fraction (72.16 ± 1.0) % and ethyl acetate fraction (70.76 ± 0.49) %. The statistical analysis revealed that total phenolic and total flavonoid content of the samples had the significant (p < 0.05) impact on DPPH free radical scavenging and α-glucosidase inhibitory activity. Current results proposed the therapeutic potential of Clinacanthus nutans, especially ethyl acetate and butanol fraction as chemotherapeutic agent against oxidative related cellular damages and control the postprandial hyperglycemia. The phytochemical investigation showed the existence of active constituents in Clinacanthus nutans extract and fractions.

Human Cytochrome P450 Enzyme Modulation by Gymnema sylvestre: A Predictive Safety Evaluation by LC-MS/MS.

PubMed

Rammohan, Bera; Samit, Karmakar; Chinmoy, Das; Arup, Saha; Amit, Kundu; Ratul, Sarkar; Sanmoy, Karmakar; Dipan, Adhikari; Tuhinadri, Sen

2016-07-01

Traditionally GS is used to treat diabetes mellitus. Drug-herb interaction of GS via cytochrome P450 enzyme system by substrate cocktail method using HLM has not been reported. To evaluate the in-vitro modulatory effects of GS extracts (aqueous, methanol, ethyl acetate, chloroform and n -hexane) and deacylgymnemic acid (DGA) on human CYP1A2, 2C8, 2C9, 2D6 and 3A4 activities in HLM. Probe substrate-based LCMS/MS method was established for all CYPs. The metabolite formations were examined after incubation of probe substrates with HLM in the presence or absence of extracts and DGA. The inhibitory effects of GS extracts and DGA were characterized with kinetic parameters IC50 and Ki values. GS extracts showed differential effect on CYP activities in the following order of inhibitory potency: ethyl acetate > Chloroform > methanol > n -hexane > aqueous > DGA. This differential effect was observed against CYP1A2, 2C9 and less on CYP3A4 and 2C8 but all CYPs were unaffected by aqueous extract and DGA. The ethyl acetate and chloroform extract exhibited moderate inhibition towards CYP1A2 and 3A4. The aqueous extract and DGA however showed negligible inhibition towards all five major human CYPs with very high IC50 values (>90μg/ml). The results of our study revealed that phytoconstituents contained in GS, particularly in ethyl acetate and chloroform extracts, were able to inhibit CYP1A2, 3A4 and 2C9. The presence of relatively small, lipophillic yet slightly polar compounds within the GS extracts may be attributed for inhibition activities. These suggest that the herb or its extracts should be examined for potential pharmacokinetic drug interactions in vivo . Abbreviations used: GS: Gymnema sylvestre , GSE: Gymnema sylvestre extract, DGA: deacyl gymnemic acid, CYP: cytochrome P450, DMSO: dimethylsulphoxide, HLM: human liver microsomes, LC-MS/MS: liquid chromatography tandem mass spectroscopy, NADPH: reduced nicotinamide adeninedinucleotide phosphate, NRS: nicotinamide adeninedinucleotide phosphate regenerating system, CHE: chloroform extract, EAE: ethyl acetate extract, NHE- n -hexane extract, AE: aqueous extract, ME: methanol extract.

Aqueous and organic extracts of Trigonella foenum-graecum L. inhibit the mycelia growth of fungi.

PubMed

Haouala, R; Hawala, S; El-Ayeb, A; Khanfir, R; Boughanmi, N

2008-01-01

Aqueous extracts from various plant parts of fenugreek (3%) (aerial parts: leaves and stems (LS), roots (R), ground seeds (GS) and not ground seeds (NGS)) and petroleum ether, ethyl acetate and methanolic fractions of the aerial parts were assayed to determine their antifungal potential against Botrytis cinerea, Fusarium graminearum, Alternaria sp., Pythium aphanidermatum, and Rhizoctinia solani. All fenugreek plant parts showed antifungal potential and the magnitude of their inhibitory effects was species and plant parts dependent. R extract was shown less toxic (30.38%), whereas NGS extract expressed the strongest inhibition, with an average of 71.44%, followed by GS (58.56%) and LS (57.1%). Screening indicated that P. aphanidermatum was the most resistant species, with an average inhibition of 34.5%. F. graminearum, Alternaria sp. and R. solani were the most sensitive species, and were similarly inhibited (63.5%). The stability test indicated that the aqueous extracts of all plant parts lost approximately 50% of their relative activity after one month of storage at 4 degrees C, whilst they lost 60%-90% of their activity when stored at ambient temperature for one month. The antifungal activity resided mainly in the methanol fraction and the minimum inhibitory concentration (MIC) of methanol fraction witch caused total inhibition of R. solani and Alternaria sp. was 60 microg/ml. Results of current study suggested that the constituents of Trigonella foenum-graecum have potential against harmful pathogenic fungi. Therefore, fenugreek could be an important source of biologically active compounds useful for developing better new antifungal drugs.

A highly selective and stable ZnO-ZrO2 solid solution catalyst for CO2 hydrogenation to methanol

PubMed Central

Wang, Jijie; Li, Guanna; Li, Zelong; Tang, Chizhou; Feng, Zhaochi; An, Hongyu; Liu, Hailong; Liu, Taifeng; Li, Can

2017-01-01

Although methanol synthesis via CO hydrogenation has been industrialized, CO2 hydrogenation to methanol still confronts great obstacles of low methanol selectivity and poor stability, particularly for supported metal catalysts under industrial conditions. We report a binary metal oxide, ZnO-ZrO2 solid solution catalyst, which can achieve methanol selectivity of up to 86 to 91% with CO2 single-pass conversion of more than 10% under reaction conditions of 5.0 MPa, 24,000 ml/(g hour), H2/CO2 = 3:1 to 4:1, 320° to 315°C. Experimental and theoretical results indicate that the synergetic effect between Zn and Zr sites results in the excellent performance. The ZnO-ZrO2 solid solution catalyst shows high stability for at least 500 hours on stream and is also resistant to sintering at higher temperatures. Moreover, no deactivation is observed in the presence of 50 ppm SO2 or H2S in the reaction stream. PMID:28989964

Radiolysis study of genistein in methanolic solution

NASA Astrophysics Data System (ADS)

Jung, Hee Jin; Park, Hae Ran; Jung, Uhee; Jo, Sung Kee

2009-06-01

The aim of the present work was to identify products obtained from genistein by ionizing radiation and to enhance the antioxidant properties of genistein through radiation-induced transformation. Genistein dissolved in methanol was irradiated γ-rays at a dose of 100 kGy. NMR and (HR) EI-MS spectroscopy were used to identify radiolysis products (GM1 and GM2). We proposed that rad CH 2OH may be implicated in the formation GM1 and GM2 during radiolysis of genistein in methanol. The genistein in methanol solution showed higher DPPH radical scavenging activity after γ-irradiation. Then, the antioxidant activities of radiolysis products were evaluated and compared to those of genistein.

PROCESS OF REMOVING PLUTONIUM VALUES FROM SOLUTION WITH GROUP IVB METAL PHOSPHO-SILICATE COMPOSITIONS

DOEpatents

Russell, E.R.; Adamson, A.W.; Schubert, J.; Boyd, G.E.

1957-10-29

A process for separating plutonium values from aqueous solutions which contain the plutonium in minute concentrations is described. These values can be removed from an aqueous solution by taking an aqueous solution containing a salt of zirconium, titanium, hafnium or thorium, adding an aqueous solution of silicate and phosphoric acid anions to the metal salt solution, and separating, washing and drying the precipitate which forms when the two solutions are mixed. The aqueous plutonium containing solution is then acidified and passed over the above described precipi-tate causing the plutonium values to be adsorbed by the precipitate.

Use of a Brine Shrimp Assay to Study Herbal Teas in the Classroom.

ERIC Educational Resources Information Center

Opler, Annette; Mizell, Rebecca; Robert, Alexander; Cervantes-Cervantes, Miguel; Kincaid, Dwight; Kennelly, Edward J.

2002-01-01

Introduces a brine shrimp assay to demonstrate the effects of the biological activity of herbal remedies. Describes two protocols, one using aqueous extracts and the other using methanol extracts. (Contains 21 references.) (YDS)

Comment on "Relating side chain organization of PNIPAm with its conformation in aqueous methanol" by D. Mukherji, M. Wagner, M. D. Watson, S. Winzen, T. E. de Oliveira, C. M. Marques and K. Kremer, Soft Matter, 2016, 12, 7995.

PubMed

van der Vegt, Nico F A; Rodríguez-Ropero, Francisco

2017-03-22

In a recent paper, Mukherji et al. describe the collapse of poly(N-isopropyl acrylamide) in methanol-water mixtures based on experiments and molecular dynamics simulations. The conclusion of their work is that chain collapse is dominated by enthalpic bridging interactions while entropic effects play no major role. Here we show that this claim arises from an improper interpretation of preferential binding and the corresponding thermodynamic data presented. When interpreted correctly, the data instead provide evidence for repulsive enthalpic interactions of methanol with the polymer, supporting the emerging view of entropic chain collapse.

Assessment of in vitro and in vivo anthelminthic potential of extracts of Allium sativum bulb against naturally occurring ovine gastrointestinal nematodiosis.

PubMed

Kanojiya, Dharmendra; Shanker, Daya; Sudan, Vikrant; Jaiswal, Amit Kumar; Parashar, Rahul

2015-01-01

The rapid development of anthelminthic resistance has limited the success of traditional control programmes, thereby forcing researchers to search for ethno-veterinary alternatives. The objective is to assess the anthelminthic potential of various extracts of the bulb of Allium sativum in naturally infected sheep. In vitro anthelminthic activities of crude aqueous and methanolic extracts of the bulb of A. sativum were investigated against the egg (500 eggs/ml) and larvae of naturally infected sheep. The aqueous extract of A. sativum was also investigated for in vivo anthelminthic activity in three groups (n = 15 each) of naturally infected Chokla sheep with a negative control group receiving no treatment, a positive control group was given a single oral dose of albendazole at 7.5 mg/kg bodyweight, and a group administered a single oral dose of an aqueous extract at 5 g/animal. Data were analysed using the general linear model. Aqueous extract showed better efficacy in egg hatch assay and larval development test. However, in larval paralysis test, reverse trend was seen as methanolic extract was more potent than the aqueous counterpart. A significant amount of 57% faecal egg count reduction was observed in in vivo trail using the aqueous extract on day 21 post-treatment, although in initial stages it showed 30% and 83% effectiveness on days 7 and 14 post-treatment, respectively. No deleterious ill effect was found in any of the haematological and biochemical parameters. Bulb of A. sativum possesses good anthelminthic efficacy and further research is thereby warranted before recommending it for nematode control programme in ovines.

Evaluation of in vitro antidiabetic and antioxidant characterizations of Elettaria cardamomum (L.) Maton (Zingiberaceae), Piper cubeba L. f. (Piperaceae), and Plumeria rubra L. (Apocynaceae).

PubMed

Ahmed, Afnan Sh; Ahmed, Qamaruddin; Saxena, Anil Kumar; Jamal, Parveen

2017-01-01

Inhibition of intestinal α-amylase and α-glucosidase is an important strategy to regulate diabetes mellitus (DM). Antioxidants from plants are widely regarded in the prevention of diabetes. Fruits of Elettaria cardamomum (L.) Maton (Zingiberaceae) and Piper cubeba L. f. (Piperaceae) and flowers of Plumeria rubra L. (Apocynaceae) are traditionally used to cure DM in different countries. However, the role of these plants has been grossly under reported and is yet to receive proper scientific evaluation with respect to understand their traditional role in the management of diabetes especially as digestive enzymes inhibitors. Hence, methanol and aqueous extracts of the aforementioned plants were evaluated for their in vitro α-glucosidase and α-amylase inhibition at 1 mg/mL and quantification of their antioxidant properties (DPPH, FRAP tests, total phenolic and total flavonoids contents). In vitro optimization studies for the extracts were also performed to enhance in vitro biological activities. The % inhibition of α-glucosidase by the aqueous extracts of the fruits of E. cardamomum, P. cubeba and flowers of P. rubra were 10.41 (0.03), 95.19 (0.01), and -2.92 (0.03), while the methanol extracts exhibited % inhibition 13.73 (0.02), 92.77 (0.01), and -0.98 (0.01), respectively. The % inhibition of α-amylase by the aqueous extracts were 82.99 (0.01), 64.35 (0.01), and 20.28 (0.02), while the methanol extracts displayed % inhibition 39.93 (0.01), 31.06 (0.02), and 39.40 (0.01), respectively. Aqueous extracts displayed good in vitro antidiabetic and antioxidant activities. Moreover, in vitro optimization experiments helped to increase the α-glucosidase inhibitory activity of E. cardamomum. Our findings further justify the traditional claims of these plants as folk medicines to manage diabetes, however, through digestive enzymes inhibition effect.

Antidiabetic Effects of Aqueous and Dichloromethane/Methanol Stem Bark Extracts of Pterocarpus soyauxii Taub (Papilionaceae) on Streptozotocin-induced Diabetic Rats

PubMed Central

Tchamadeu, Marie Claire; Dzeufiet, Paul Désiré Djomeni; Blaes, Nelly; Girolami, Jean-Pierre; Kamtchouing, Pierre; Dimo, Théophile

2017-01-01

Aim of the Study: The aim is to evaluate the hypoglycemic and antidiabetic effects of aqueous and CH2Cl2/CH3OH stem bark extracts of Pterocarpus soyauxii Taub in normal and diabetic rats. Materials and Methods: Streptozotocin (STZ)-induced diabetic and normal adult Wistar rats were orally administered with aqueous and CH2Cl2/CH3OH plant extracts of P. soyauxii at various doses (38–300 mg/kg) in a single administration. In addition, STZ-induced diabetic rats received prolonged daily administration for 14 days. Glibenclamide (GB) (10 mg/kg) was used as reference treatment. In acute test, fasting blood glucose was followed for 5 h. In subacute test, body weight, food and water intakes, and blood glucose were followed weekly and serum biochemical parameters evaluated after 14 days treatment. Results: Acute administration of aqueous and CH2Cl2/CH3OH stem bark extracts moderately decreased fasting blood glucose compared to GB, significantly in normal rats (P < 0.05 to P < 0.01) but, as GB, not significantly in diabetic rats. Prolonged treatments in diabetic rats with aqueous and CH2Cl2/CH3OH extracts reduced blood glucose to an extent, respectively, superior or similar to GB. Moreover, P. soyauxii also significantly (P < 0.01) reduced weight loss, and diabetes increased serum triglycerides, total cholesterol, and transaminases (alanine aminotransferase/aspartate aminotransferase) elevations. Conclusion: P. soyauxii Taub stem bark extracts have possible value for antidiabetic oral medication. SUMMARY Aqueous and Dichloromethane/Methanol stem bark extracts of Pterocarpus soyauxii Taub have potent (compared to Glibenclamide) antidiabetic effects in STZ-diabetic rats, with specific kinetics and dose-responses.Moderate hypoglycemia effects upon acute P. soyauxii administration.Potent anti-hyperglycemic effects of sub-acute P. soyauxii administration in STZ-diabetic rats.Potent anti-hyperlipidemic effects of sub-acute P. soyauxii administration in STZ-diabetic rats.Improved hepatic and renal serum parameters after sub-acute P. soyauxii administration in STZ-diabetic rats.P. soyauxii extracts may be useful for oral treatment of diabetes and related metabolic disorders. Abbreviations Used: CH2Cl2/CH3OH: Dichloromethane/Methanol; STZ: Streptozotocin; GB: Glibenclamide; AE: Aqueous extract; OE: Organic extract; FeCl3: Iron (III) chloride; NaCl: Sodium chloride; K3Fe(CN)6: Potassium ferricyanide; ALT: Alanine aminotransferase; AST: Aspartate aminotransferase; H: Hour; BW: Body weight, W1 and W2: Weeks 1 and 2; CHOD: Cholesterol oxidase; GPO: Glycerol-3 Phosphate oxidase; PAP: Phenol + Aminophenazone PMID:28250659

Methanol production method and system

DOEpatents

Chen, Michael J.; Rathke, Jerome W.

1984-01-01

Ethanol is selectively produced from the reaction of methanol with carbon monoxide and hydrogen in the presence of a transition metal carbonyl catalyst. Methanol serves as a solvent and may be accompanied by a less volatile co-solvent. The solution includes the transition metal carbonyl catalysts and a basic metal salt such as an alkali metal or alkaline earth metal formate, carbonate or bicarbonate. A gas containing a high carbon monoxide to hydrogen ratio, as is present in a typical gasifer product, is contacted with the solution for the preferential production of ethanol with minimal water as a byproduct. Fractionation of the reaction solution provides substantially pure ethanol product and allows return of the catalysts for reuse.

Introducing Urtica dioica, A Native Plant of Khuzestan, As an Antibacterial Medicinal Plant

PubMed Central

Motamedi, Hossein; Seyyednejad, Seyyed Mansour; Bakhtiari, Ameneh; Vafaei, Mozhan

2014-01-01

Background: Urtica dioica is a flowering plant with long history of use in folk medicine and as a food source. Objectives: This study examined in vitro antibacterial potential of alcoholic extracts of U. dioica. Materials and Methods: Hydroalcoholic extracts from aerial parts were prepared using aqueous solution of ethanol and methanol and their inhibitory effects against clinical isolates was examined by disc diffusion method at different doses. Minimum inhibitory concentrations (MIC) and minimum bactericidal concentration (MBC) indexes were also investigated. The scanning electron microscopy (SEM) analysis was also performed to find structural changes of affected bacteria consequent to exposing with extracts. Results: Both extracts were active against Bacillus cereus, Staphylococcus aureus, Staphylococcus epidermidis, and Escherichia coli with respectively 16, 10, 18, and 14 mm (methanolic) and 11, 9, 17, and 16 mm (ethanolic) inhibition zone. The MIC of ethanolic extract against S. epidermidis and E. coli was respectively 10 and 40 mg/mL. The MIC of methanolic extract against S. aureus and S. epidermidis was 40 and 10 mg/mL, respectively. The MBC was found only for S. epidermidis (20 mg/mL). In SEM analysis the round shape of S. epidermidis was changed and irregular shapes were appeared, which suggest that the main target of these extracts was cell wall. Conclusions: Extracts of U. dioica showed significant antibacterial effect against some clinically important pathogenic bacteria. Based on the obtained results it can be concluded that U. dioica is useful as antibacterial and bactericidal agent in treating infectious diseases. PMID:25625045

Electrochemical Reduction of Protic Supercritical CO2 on Copper Electrodes.

PubMed

Melchaeva, Olga; Voyame, Patrick; Bassetto, Victor Costa; Prokein, Michael; Renner, Manfred; Weidner, Eckhard; Petermann, Marcus; Battistel, Alberto

2017-09-22

The electrochemical reduction of carbon dioxide is usually studied in aqueous solutions under ambient conditions. However, the main disadvantages of this method are high hydrogen evolution and low faradaic efficiencies of carbon-based products. Supercritical CO 2 (scCO 2 ) can be used as a solvent itself to suppresses hydrogen evolution and tune the carbon-based product yield; however, it has received little attention for this purpose. Therefore, the focus of this study was on the electrochemical reduction of scCO 2 . The conductivity of scCO 2 was increased through the addition of supporting electrolyte and a cosolvent (acetonitrile). Furthermore, the addition of protic solutions of different pH to scCO 2 was investigated. 1 m H 2 SO 4 , trifluoroethanol, H 2 O, KOH, and CsHCO 3 solutions were used to determine the effect on current density, faradaic efficiency, and selectivity of the scCO 2 reduction. The reduction of scCO 2 to methanol and ethanol are reported for the first time. However, methane and ethylene were not observed. Additionally, corrosion of the Cu electrode was noticed. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

High-pressure liquid chromatographic analysis of pramoxine hydrochloride in high lipoid aerosol foam dosage form.

PubMed

Weinberger, R; Mann, B; Posluszny, J

1980-04-01

A rapid and quantitative method for the determination of pramoxine hydrochloride by high-pressure liquid chromatography is presented. The drug is extracted as the salt from a preparation with a high lipoid composition by partitioning it to the aqueous phase of an ether-methanol-water-acetic acid system. The extract is chromatographed on an octadecylsilane bonded packing with a methanol-water-acetic acid-methanesulfonic acid mobile phase. The time required for each separation is approximately 6 min. Analytical recoveries of 100.4 +/- 1.5% were obtained.

Anti-tumor effect of Coriolus versicolor methanol extract against mouse B16 melanoma cells: in vitro and in vivo study.

PubMed

Harhaji, Lj; Mijatović, S; Maksimović-Ivanić, D; Stojanović, I; Momcilović, M; Maksimović, V; Tufegdzić, S; Marjanović, Z; Mostarica-Stojković, M; Vucinić, Z; Stosić-Grujicić, S

2008-05-01

Numerous studies have shown immunostimulatory and anti-tumor effects of water and standardized aqueous ethanol extracts derived from the medicinal mushroom, Coriolus versicolor, but the biological activity of methanol extracts has not been examined so far. In the present study we investigated the anti-tumor effect of C. versicolor methanol extract (which contains terpenoids and polyphenols) on B16 mouse melanoma cells both in vitro and in vivo. In vitro treatment of the cells with the methanol extract (25-1600 microg/ml) reduced melanoma cell viability in a dose-dependent manner. Furthermore, in the presence of the methanol extract (200 microg/ml, concentration IC(50)) the proliferation of B16 cells was arrested in the G(0)/G(1) phase of the cell cycle, followed by both apoptotic and secondary necrotic cell death. In vivo methanol extract treatment (i.p. 50 mg/kg, for 14 days) inhibited tumor growth in C57BL/6 mice inoculated with syngeneic B16 tumor cells. Moreover, peritoneal macrophages collected 21 days after tumor implantation from methanol extract-treated animals exerted stronger tumoristatic activity ex vivo than macrophages from control melanoma-bearing mice. Taken together, our results demonstrate that C. versicolor methanol extract exerts pronounced anti-melanoma activity, both directly through antiproliferative and cytotoxic effects on tumor cells and indirectly through promotion of macrophage anti-tumor activity.

Inhibition of myeloperoxidase and antioxidative activity of Gentiana lutea extracts.

PubMed

Nastasijević, Branislav; Lazarević-Pašti, Tamara; Dimitrijević-Branković, Suzana; Pašti, Igor; Vujačić, Ana; Joksić, Gordana; Vasić, Vesna

2012-07-01

The aim of this study was to investigate the inhibitory activity of Gentiana lutea extracts on the enzyme myeloperoxidase (MPO), as well as the antioxidant activity of these extracts and their correlation with the total polyphenol content. Extracts were prepared using methanol (100%), water and ethanol aqueous solutions (96, 75, 50 and 25%v/v) as solvents for extraction. Also, isovitexin, amarogentin and gentiopicroside, pharmacologically active constituents of G. lutea were tested as potential inhibitors of MPO. Antioxidant activity of extracts was determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging test and also using cyclic voltammetry (CV). Among all extracts, the antioxidant capacity of 50% ethanol aqueous extract was the highest, both when measured using the DPPH test, with IC(50)=20.6 μg/ml, and when using CV. Also, 50% ethanol extract, showed the best inhibition of MPO activity in comparison with other extracts. In the group of the selected G. lutea constituents, gentiopicroside has proved to be the strongest inhibitor of MPO, with IC(50)=0.8 μg/ml. Also, the concentration of G. lutea constituents were determined in all extracts, using Ultra Performance Liquid Chromatography (UPLC). Copyright © 2012 Elsevier B.V. All rights reserved.

[Direct determination of purine bases in tea by reversed-phase high performance liquid chromatography].

PubMed

Ding, M; Yang, H; Xiao, S; Chen, P

1999-09-01

A reversed-phase high performance liquid chromatographic(RP-HPLC) method for the direct determination of three purine bases(theobromin, theophyllin and caffeine) in tea was developed. An ODS column with Zorbax SB-C18(4.6 mm i.d. x 250 mm, 5 microns) was employed. The aqueous solution of methanol containing 0.05% of acetic acid and 0.25% of N,N-dimethylformamide(DMF) was used as eluent with a flow rate of 0.8 mL/min. In this method, the aqueous extract of tea can be injected into HPLC directly, but in current HPLC methods for purine bases the coexisted tea polyphenols must be pre-separated. The three purine bases in tea were separated without any interference from the coexisted tea polyphenols. This method is simple (without any special sample pretreatment) and sensitive with detection limits (S/N = 3) of 0.7, 0.9 and 1.8 mg/L for theobromin, theophyllin and caffeine respectively. The linear range of the calibration curve of peak area for the three purine bases were from 6 mg/L to 1,000 mg/L with a correlation coefficient (r) of 0.998-0.999.

Morphological Diversity in Crystal Growth of l-Ascorbic Acid Dissolved in Methanol

NASA Astrophysics Data System (ADS)

Ito, Miho; Izui, Machiko; Yamazaki, Yoshihiro; Matsushita, Mitsugu

2003-06-01

Morphological diagram with respect to crystal growth of l-ascorbic acid (C6H8O6; so-called vitamin C) from methanol solution on a flat glass dish is presented. Varying humidity and initial concentration of l-ascorbic acid in methanol solution, the following three distinct kinds of growing patterns have been observed: homogeneous disk, concentric ring and dendrite. In addition, in higher concentration clearly faceted small single crystals grow in any humidity less than 90%. Crossovers from one pattern to another were observed, too.

MTBE Hydrolysis in Dilute Aqueous Solution Using Heterogeneous Strong Acid Catalysts

NASA Astrophysics Data System (ADS)

Rixey, W. G.

2003-12-01

The objective of this research has been the development of a potential in situ catalytic process for the hydrolysis of methyl tertiary butyl ether (MTBE) to tertiary butyl alcohol (TBA) and methanol in ground water. Bench-scale batch reactor studies were conducted over a temperature range of 23 deg C to 50 deg C with several heterogeneous strong acid catalysts to obtain rates of hydrolysis of MTBE to TBA and methanol at dilute concentrations in water. Continuous flow experiments were then conducted to obtain kinetic data over a temperature range of 15 deg C to 50 deg C for various flow rates for the most active catalysts. It was found that the batch and continuous flow experiments yielded similar intrinsic kinetic rate constants when sorption of MTBE to the catalyst was accounted for. Additional fixed-bed experiments were conducted with deionized water and 0.005 M CaCl2 feed solutions containing 100 mg/L MTBE, respectively, to assess the deactivation of the catalyst, and deactivation was found to be controlled by ion exchange of H+ in the catalyst with Ca+2 in the feed. Our results indicate that, for low to moderate groundwater velocities and cation concentrations at ambient temperatures, an in situ reactive barrier process using the most active catalysts studied in this research could be a viable process in terms of both suitable conversion of MTBE and catalyst life. Although application to in situ remediation is emphasized, the results of this research are also applicable to ex-situ groundwater treatment.

Quadrupole terms in the Maxwell equations: Debye-Hückel theory in quadrupolarizable solvent and self-salting-out of electrolytes.

PubMed

Slavchov, Radomir I

2014-04-28

If the molecules of a given solvent possess significant quadrupolar moment, the macroscopic Maxwell equations must involve the contribution of the density of the quadrupolar moment to the electric displacement field. This modifies the Poisson-Boltzmann equation and all consequences from it. In this work, the structure of the diffuse atmosphere around an ion dissolved in quadrupolarizable medium is analyzed by solving the quadrupolar variant of the Coulomb-Ampere's law of electrostatics. The results are compared to the classical Debye-Hückel theory. The quadrupolar version of the Debye-Hückel potential of a point charge is finite even in r = 0. The ion-quadrupole interaction yields a significant expansion of the diffuse atmosphere of the ion and, thus, it decreases the Debye-Hückel energy. In addition, since the dielectric permittivity of the electrolyte solutions depends strongly on concentration, the Born energy of the dissolved ions alters with concentration, which has a considerable contribution to the activity coefficient γ± known as the self-salting-out effect. The quadrupolarizability of the medium damps strongly the self-salting-out of the electrolyte, and thus it affects additionally γ±. Comparison with experimental data for γ± for various electrolytes allows for the estimation of the quadrupolar length of water: LQ ≈ 2 Å, in good agreement with previous assessments. The effect of quadrupolarizability is especially important in non-aqueous solutions. Data for the activity of NaBr in methanol is used to determine the quadrupolarizability of methanol with good accuracy.

Electrolytic synthesis of methanol from CO.sub.2

DOEpatents

Steinberg, Meyer

1976-01-01

A method and system for synthesizing methanol from the CO.sub.2 in air using electric power. The CO.sub.2 is absorbed by a solution of KOH to form K.sub.2 CO.sub.3 which is electrolyzed to produce methanol, a liquid hydrocarbon fuel.

High-performance liquid chromatographic determination of certain salicylates and their major metabolites in plasma following topical administration of a liniment to healthy subjects.

PubMed

Dadgar, D; Climax, J; Lambe, R; Darragh, A

1985-08-09

The liniment used is a topical analgesic and anti-inflammatory preparation containing two active constituents, 3-phenylpropylsalicylate and ethyl-5-methoxysalicylate, in solution in isobutyl decanoate. It is known that 3-phenylpropylsalicylate is metabolised to salicylic acid and salicyluric acid and ethyl-5-methoxysalicylate is metabolised to 5-methoxysalicylic acid and gentisic acid. In the present study the separation of the salicylates and their metabolites was carried out on a Waters mu Bondapak C18 column using two different mobile phases, methanol-water (80:20) for the parent drugs and methanol-5% aqueous acetic acid (27:73) for their metabolites. The salicylates and their metabolites were detected by absorption at 310 nm. The limits of detection for parent drugs and metabolites were respectively 0.2 and 0.1 microgram/ml in plasma, using a 1-ml plasma sample and a 20-microliter injection from a reconstituted volume of 250 microliter. Mean percentage coefficients of variation for intra-assay and inter-assay precision were between 3.3 +/- 1.9% to 9.1 +/- 3.7% and 6.8 +/- 2.2% to 15.7 +/- 10.1%, respectively. Linearity, as measured by the correlation coefficient of intra-assay linear regression curves, was better than 0.998 in all cases.

Electro-catalytic biodiesel production from canola oil in methanolic and ethanolic solutions with low cost stainless steel and hybrid ion-exchange resin grafted electrodes

NASA Astrophysics Data System (ADS)

Allioux, Francois-Marie; Holland, Brendan J.; Kong, Lingxue; Dumée, Ludovic F.

2017-07-01

Biodiesel is a growing alternative to petroleum fuels and is produced by the catalysed transesterification of fats in presence of an alcohol base. Transesterification processes using homogeneous catalysts are considered to be amongst the most efficient methods but rely on the feedstock quality and low water content in order to avoid undesirable saponification reactions. In this work, the electro-catalytic conversion of canola oil to biodiesel in a 1% aqueous methanolic and ethanolic reaction mixture was performed without the addition of external catalyst or co-solvent. An inexpensive stainless steel electrode and a hybrid stainless steel electrode coated with an ion-exchange resin catalyst were used as cathode materials while the anode was composed of a plain carbon paper. The cell voltages were varied from 10 to 40 V and the reaction temperature maintained at 20 or 40°C. The canola oil conversion rates were found to be superior at 40°C without saponification reactions for cell voltages below 30 V. The conversion rates were as high as 87% for the hybrid electrode and 81% for the plain stainless steel electrode. This work could inspire new process development for the conversion of high water content feedstock for the production of second-generation biodiesel.

Electrocatalysis of carbon black- or poly(diallyldimethylammonium chloride)-functionalized activated carbon nanotubes-supported Pd-Tb towards methanol oxidation in alkaline media

NASA Astrophysics Data System (ADS)

Wang, Li; Wang, Yi; Li, An; Yang, Yunshang; Tang, Qinghu; Cao, Hongbin; Qi, Tao; Li, Changming

2014-07-01

The Pd-Tb/C catalysts with different Pd/Tb ratios were synthesized by a simple simultaneous reduction reaction with sodium borohydride in aqueous solution. The structure and morphology of those catalysts had been characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The electrocatalytic performance of those catalysts for methanol oxidation in alkaline media was investigated using cyclic voltammetry (CV), linear sweep voltammetry (LSV) and CO stripping experiments. It is found that the 20%Pd-1%Tb/C catalyst has a higher catalytic activity than the 20%Pd/C catalyst, but the effect of Tb cannot be explained by a bi-functional mechanism. According to the X-Ray photoelectron spectroscopy (XPS) analyses, it is suggested that the higher content of metallic Pd caused by the addition of Tb contributes to the better catalytic activity of 20%Pd-1%Tb/C. Based on the good electrocatalytic performance of 20%Pd-1%Tb/C, the 20%Pd-1%Tb catalyst supported on poly(diallyldimethylammonium chloride) (PDDA)-functionalized activated carbon nanotubes was prepared, and it exhibits a better catalytic activity. The improvement mainly results from the further increase of metallic Pd due to the presence of PDDA.

Carbon-supported Pd-Co as cathode catalyst for APEMFCs and validation by DFT.

PubMed

Maheswari, S; Karthikeyan, S; Murugan, P; Sridhar, P; Pitchumani, S

2012-07-21

Carbon supported PdCo catalysts in varying atomic ratios of Pd to Co, namely 1 : 1, 2 : 1 and 3 : 1, were prepared. The oxygen reduction reaction (ORR) was studied on commercial carbon-supported Pd and carbon-supported PdCo nanocatalysts in aqueous 0.1 M KOH solution with and without methanol. The structure, dispersion, electrochemical characterization and surface area of PdCo/C were determined by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM) and Cyclic Voltammetry (CV), respectively. The electrochemical activity for ORR was evaluated from Linear Sweep Voltammograms (LSV) obtained using a rotating ring disk electrode. The catalysts were evaluated for their electrocatalytic activity towards oxygen reduction reaction (ORR) in Alkaline Polymer Electrolyte Membrane Fuel Cells (APEMFCs). PdCo(3 : 1)/C gives higher performance (85 mW cm(-2)) than PdCo(1 : 1)/C, PdCo(2 : 1)/C and Pd/C. The maximum electrocatalytic activity for ORR in the presence of methanol was observed for PdCo(3 : 1)/C. First principles calculations within the framework of density functional theory were performed to understand the origin of its catalytic activity based on the energy of adsorption of an O(2) molecule on the cluster, structural variation and charge transfer mechanism.

Controlling silk fibroin particle features for drug delivery

PubMed Central

Lammel, Andreas; Hu, Xiao; Park, Sang-Hyug; Kaplan, David L.; Scheibel, Thomas

2010-01-01

Silk proteins are a promising material for drug delivery due to their aqueous processability, biocompatibility, and biodegradability. A simple aqueous preparation method for silk fibroin particles with controllable size, secondary structure and zeta potential is reported. The particles were produced by salting out a silk fibroin solution with potassium phosphate. The effect of ionic strength and pH of potassium phosphate solution on the yield and morphology of the particles was determined. Secondary structure and zeta potential of the silk particles could be controlled by pH. Particles produced by salting out with 1.25 M potassium phosphate pH 6 showed a dominating silk II (crystalline) structure whereas particles produced at pH 9 were mainly composed of silk I (less crystalline). The results show that silk I rich particles possess chemical and physical stability and secondary structure which remained unchanged during post treatments even upon exposure to 100% ethanol or methanol. A model is presented to explain the process of particle formation based on intra- and intermolecular interactions of the silk domains, influenced by pH and kosmotrope salts. The reported silk fibroin particles can be loaded with small molecule model drugs, such as alcian blue, rhodamine B, and crystal violet, by simple absorption based on electrostatic interactions. In vitro release of these compounds from the silk particles depends on charge – charge interactions between the compounds and the silk. With crystal violet we demonstrated that the release kinetics are dependent on the secondary structure of the particles. PMID:20219241

Improved procedure for determination of flucytosine in human blood plasma by high-pressure liquid chromatography.

PubMed Central

Schwertschlag, U; Nakata, L M; Gal, J

1984-01-01

Several high-pressure liquid chromatography procedures for the determination of flucytosine in serum or plasma have appeared. Some of these suffer from significant disadvantages, and none was applicable in our routine clinical therapeutic-drug-monitoring laboratory. A new high-pressure liquid chromatography assay for flucytosine was therefore developed. A 100-microliter sample of plasma was treated with an aqueous 5-iodocytosine internal-standard solution, and the mixture was deproteinized with trichloroacetic acid. A portion of the protein-free supernatant was diluted with 0.1 M ammonium phosphate, and an aliquot of the resulting solution was injected into the high-pressure liquid chromatography system. Chromatography was performed on a strong-cation-exchange column with a mobile phase containing aqueous ammonium phosphate, phosphoric acid, methanol, and acetonitrile. Detection was at 254 nm. The assay was shown to be linear in the 10 to 200-micrograms/ml drug-concentration range. Forty other drugs were tested for potential interference with the assay, and none was found. For routine use, a single-point working standard containing 75 micrograms of flucytosine per ml was used, giving intraassay coefficients of variation at 50 and 150 micrograms/ml of 1.8 and 2.3% respectively, whereas the day-to-day coefficient of variation at 50 micrograms/ml was 10.0%. Advantages of the procedure include the small sample size, the use of a convenient and reliable internal standard, speed, and simplicity. The assay is highly suitable for routine clinical drug-analysis laboratories. PMID:6508261

Real-time ESI-MS of enzymatic conversion: impact of organic solvents and multiplexing.

PubMed

Scheerle, Romy K; Grassmann, Johanna; Letzel, Thomas

2012-01-01

Different enzymatic assays were characterized systematically by real-time electrospray ionization mass spectrometry (ESI-MS) in the presence of organic solvents as well as in multiplex approaches and in a combination of both. Typically, biological enzymatic reactions are studied in aqueous solutions, since most enzymes show their full activity solely in aqueous solutions. However, in recent years, the use of organic solvents in combination with enzymatic reactions has gained increasing interest due to biotechnological advantages in chemical synthesis, development of online coupled setups screening for enzyme regulatory compounds, advantages regarding mass spectrometric detection and others. In the current study, the influence of several common organic solvents (methanol, ethanol, isopropanol, acetone, acetonitrile) on enzymatic activity (hen egg white lysozyme, chitinase, α-chymotrypsin, elastase from human neutrophils and porcine pancreas, acetylcholinesterase) was tested. Moreover, multiplexing is a promising approach enabling fast and cost-efficient screening methods, e.g. for determination of inhibitors in complex mixtures or in the field of biomedical research. Although in multiplexed setups the enzymatic activity may be affected by the presence of other substrates and/or enzymes, the expected advantages possibly will predominate. To investigate those effects, we measured multiple enzymatic assays simultaneously. For all conducted measurements, the conversion rate of the substrate(s) was calculated, which reflects the enzymatic activity. The results provide an overview about the susceptibility of the selected enzymes towards diverse factors and a reference point for many applications in analytical chemistry and biotechnology.

[Determination of 11 mycotoxins in baked foods and raw materials by ultra performance liquid chromatography-quadrupole/electrostatic field orbitrap high-resolution mass spectrometry].

PubMed

Li, Rong; He, Chunmei; Yang, Luqi; Wang, Yong; Zhang, Pengjie; Gao, Yongqing

2017-08-08

A method for the determination of 11 mycotoxins in baked foods and raw materials by ultra-high performance liquid chromatography-quadrupole/electrostatic field orbitrap high-resolution mass spectrometry (UPLC-HRMS) is reported in this paper. The samples were extracted with 20 mL 90% (v/v) acetonitrile aqueous solution containing 1% (v/v) formic acid, and the extracts were salted out by 2.0 g MgSO 4 and 0.5 g NaCl, cleaned up by 300 mg C18. The analytes were carried out on a CORTECS C18 column (100 mm×2.1 mm, 1.6 μ m) by gradient elution with 2 mmol/L ammonium acetate with 0.1% (v/v) formic acid aqueous solution and 2 mmol/L ammonium acetate methanol with 0.1% (v/v) formic acid. The results showed that the 11 mycotoxins had good linear relationships in their respective mass concentration ranges. The correlation coefficients were not less than 0.9960 and the limits of quantitation (LOQs) were from 0.15 to 20.00 μ g/kg. The recoveries of the 11 mycotoxins in bread ranged from 64.38% to 122.61% with the relative standard deviations (RSDs) from 1.52% to 12.99% at three spiked levels ( n =6). The method is demonstrated to be simple, fast, highly sensitive, reliable and it is effective to detect common mycotoxins in baked foods and raw materials.

Antioxidant properties of methanol extract and its solvent fractions obtained from selected Indian red seaweeds.

PubMed

Ganesan, P; Kumar, Chandini S; Bhaskar, N

2008-05-01

In vitro antioxidant activities of three selected Indian red seaweeds - viz., Euchema kappaphycus, Gracilaria edulis and Acanthophora spicifera were evaluated. Total phenolic content and reducing power of crude methanol extract were determined. The antioxidant activities of total methanol extract and five different solvent fractions (viz., petroleum ether (PE), ethyl acetate (EA), dichloromethane (DCM), butanol (BuOH) and aqueous) were also evaluated. EA fraction of A. spicifera exhibited higher total antioxidant activity (32.01 mg ascorbic acid equivalent/g extract) among all the fractions. Higher phenolic content (16.26 mg gallic acid equivalent/g extract) was noticed in PE fraction of G. edulis. Reducing power of crude methanol extract increased with increasing concentration of the extract. Reducing power and hydroxyl radical scavenging activity of E. kappaphycus were higher compared to standard antioxidant (alpha-tocopherol). The total phenol content of all the seaweeds was significantly different (P<0.05). In vitro antioxidant activities of methanol extracts of all the three seaweeds exhibited dose dependency; and increased with increasing concentration of the extract.

Antioxidant Potential of Lingzhi or Reishi Medicinal Mushroom, Ganoderma lucidum (Higher Basidiomycetes) Cultivated on Artocarpus heterophyllus Sawdust Substrate in India.

PubMed

Rani, P; Lal, Merlin Rajesh; Maheshwari, Uma; Krishnan, Sreeram

2015-01-01

The artificial cultivation of Ganoderma lucidum (MTCC1039) using Artocarpus heterophyllus as sawdust substrate was optimized and free radical scavenging activities of the generated fruiting bodies were investigated. The choice of A. heterophyllus as substrate was due to its easy availability in South India. Sawdust supplemented with dextrose medium yielded better spawn hyphae and early fruiting body initiation (15 days). The biological yield obtained was 42.06 ± 2.14 g/packet and the biological efficiency was 8.41 ± 0.48%. Both aqueous and methanolic extracts of fruiting body were analyzed for radical scavenging activity. Methanolic extract showed maximum scavenging activity for 1,1-diphenyl-2-picrylhydrazyl (IC50 = 290 μg/ml) and 2,2'-azino-bis(3-ethylbenzothiazoline- 6-sulphonic acid (IC50 = 580 μg/ml), whereas aqueous extract had better scavenging for ferric reducing antioxidant power (IC50 = 5 μg/ml). Total phenolic content and total antioxidant capacity were significantly higher in methanolic extract (p < 0.01). A positive correlation existed between the phenolic content and antioxidant activity. Our results indicated that fruiting bodies of G. lucidum cultivated in sawdust medium possess antioxidant property, which can be exploited for therapeutic application.

The use of synthesized aqueous solutions for determining strontium sorption isotherms

USGS Publications Warehouse

Liszewski, M.J.; Bunde, R.L.; Hemming, C.; Rosentreter, J.; Welhan, J.

1998-01-01

The use of synthesized aqueous solutions for determining experimentally derived strontium sorption isotherms of sediment was investigated as part of a study accessing strontium chemical transport properties. Batch experimental techniques were used to determine strontium sorption isotherms using synthesized aqueous solutions designed to chemically represent water from a natural aquifer with respect to major ionic character and pH. A strontium sorption isotherm for a sediment derived using a synthesized aqueous solution was found to be most comparable to an isotherm derived using natural water when the synthesized aqueous solution contained similar concentrations of calcium and magnesium. However, it is difficult to match compositions exactly due to the effects of disequilibrium between the solution and the sediment. Strong linear relations between sorbed strontium and solution concentrations of calcium and magnesium confirm that these cations are important co-constituents in these synthesized aqueous solutions. Conversely, weak linear relations between sorbed strontium and solution concentrations of sodium and potassium indicate that these constituents do not affect sorption of strontium. The addition of silica to the synthesized aqueous solution does not appreciably affect the resulting strontium sorption isotherm.

Activity of water in aqueous systems; a frequently neglected property.

PubMed

Blandamer, Mike J; Engberts, Jan B F N; Gleeson, Peter T; Reis, Joao Carlos R

2005-05-01

In this critical review, the significance of the term 'activity' is examined in the context of the properties of aqueous solutions. The dependence of the activity of water(l) at ambient pressure and 298.15 K on solute molality is examined for aqueous solutions containing neutral solutes, mixtures of neutral solutes and salts. Addition of a solute to water(l) always lowers its thermodynamic activity. For some solutes the stabilisation of water(l) is less than and for others more than in the case where the thermodynamic properties of the aqueous solution are ideal. In one approach this pattern is accounted for in terms of hydrate formation. Alternatively the pattern is analysed in terms of the dependence of practical osmotic coefficients on the composition of the aqueous solution and then in terms of solute-solute interactions. For salt solutions the dependence of the activity of water on salt molalities is compared with that predicted by the Debye-Hückel limiting law. The analysis is extended to consideration of the activities of water in binary aqueous mixtures. The dependence on mole fraction composition of the activity of water in binary aqueous mixtures is examined. Different experimental methods for determining the activity of water in aqueous solutions are critically reviewed. The role of water activity is noted in a biochemical context, with reference to the quality, stability and safety of food and finally with regard to health science.

Liquid-Feed Methanol Fuel Cell With Membrane Electrolyte

NASA Technical Reports Server (NTRS)

Surampudi, Subbarao; Narayanan, S. R.; Halpert, Gerald; Frank, Harvey; Vamos, Eugene

1995-01-01

Fuel cell generates electricity from direct liquid feed stream of methanol/water solution circulated in contact with anode, plus direct gaseous feed stream of air or oxygen in contact with cathode. Advantages include relative simplicity and elimination of corrosive electrolytic solutions. Offers potential for reductions in size, weight, and complexity, and for increases in safety of fuel-cell systems.

Screening of antibacterial potentials of some medicinal plants from Melghat forest in India.

PubMed

Tambekar, D H; Khante, B S; Chandak, B R; Titare, A S; Boralkar, S S; Aghadte, S N

2009-05-07

Cyperus rotundus, Caesalpinia bonducella, Tinospora cordifolia, Gardenia gummifera, Ailanthus excelsa, Acacia arabica, Embelia ribes and Ventilago maderspatana from Melghat forest were screened for their antibacterial potential against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Proteus vulgaris, Salmonella typhi, Shigella flexneri, Salmonella paratyphi, Salmonella typhimurium, Pseudomonas aeruginosa, Enterobacter aerogenes by disc diffusion method. Out of these medicinal plants Caesalpinia bonducella, Gardenia gummifera and Acacia arabica showed remarkable antibacterial potential. The phytochemical analysis had showed the presence of Cardiac glycosides in all extracts (aqueous, acetone, ethanol and methanol) of Acacia arabica, Gardenia gummifera and ethanol, methanol extracts of Caesalpinia bonducella. Flavonoids were present in Gardenia gummifera, Ailanthus excelsa and acetone, methanol extracts of Acacia Arabica. Tannins and phenolic were present in Cyperus rotundus, Embelia ribes, and organic extracts of Ventilago maderspatana.

Electro-oxidation of methanol on gold in alkaline media: Adsorption characteristics of reaction intermediates studied using time resolved electro-chemical impedance and surface plasmon resonance techniques

NASA Astrophysics Data System (ADS)

Assiongbon, K. A.; Roy, D.

2005-12-01

Electro-catalytic oxidation of methanol is the anode reaction in direct methanol fuel cells. We have studied the adsorption characteristics of the intermediate reactants of this multistep reaction on a gold film electrode in alkaline solutions by combining surface plasmon resonance (SPR) measurements with Fourier transform electro-chemical impedance spectroscopy (FT-EIS). Methanol oxidation in this system shows no significant effects of "site poisoning" by chemisorbed CO. Our results suggest that OH - chemisorbed onto Au acts as a stabilizing agent for the surface species of electro-active methanol. Double layer charging/discharging and adsorption/desorption of OH - show more pronounced effects than adsorption/oxidation of methanol in controlling the surface charge density of the Au substrate. These effects are manifested in both the EIS and the SPR data, and serve as key indicators of the surface reaction kinetics. The data presented here describe the important role of adsorbed OH - in electro-catalysis of methanol on Au, and demonstrate how SPR and FT-EIS can be combined for quantitative probing of catalytically active metal-solution interfaces.

Towards operating direct methanol fuel cells with highly concentrated fuel

NASA Astrophysics Data System (ADS)

Zhao, T. S.; Yang, W. W.; Chen, R.; Wu, Q. X.

A significant advantage of direct methanol fuel cells (DMFCs) is the high specific energy of the liquid fuel, making it particularly suitable for portable and mobile applications. Nevertheless, conventional DMFCs have to be operated with excessively diluted methanol solutions to limit methanol crossover and the detrimental consequences. Operation with diluted methanol solutions significantly reduces the specific energy of the power pack and thereby prevents it from competing with advanced batteries. In view of this fact, there exists a need to improve conventional DMFC system designs, including membrane electrode assemblies and the subsystems for supplying/removing reactants/products, so that both the cell performance and the specific energy can be simultaneously maximized. This article provides a comprehensive review of past efforts on the optimization of DMFC systems that operate with concentrated methanol. Based on the discussion of the key issues associated with transport of the reactants/products, the strategies to manage the supply/removal of the reactants/products in DMFC operating with highly concentrated methanol are identified. With these strategies, the possible approaches to achieving the goal of concentrated fuel operation are then proposed. Past efforts in the management of the reactants/products for implementing each of the approaches are also summarized and reviewed.

Membrane separation for non-aqueous solution

NASA Astrophysics Data System (ADS)

Widodo, S.; Khoiruddin; Ariono, D.; Subagjo; Wenten, I. G.

2018-01-01

Membrane technology has been widely used in a number of applications competing with conventional technologies in various ways. Despite the enormous applications, they are mainly used for the aqueous system. The use of membrane-based processes in a non-aqueous system is an emerging area. This is because developed membranes are still limited in separations involving aqueous solution which show several drawbacks when implemented in a non-aqueous system. The purpose of this paper is to provide a review of the current application of membrane processes in non-aqueous solutions, such as mineral oil treatment, vegetable oil processing, and organic solvent recovery. Developments of advanced membrane materials for the non-aqueous solutions such as super-hydrophobic and organic solvent resistant membranes are reviewed. In addition, challenges and future outlook of membrane separation for the non-aqueous solution are discussed.

A mild process to design silk scaffolds with reduced β-sheet structure and various topographies at the nanometer scale.

PubMed

Pei, Yazhen; Liu, Xi; Liu, Shanshan; Lu, Qiang; Liu, Jing; Kaplan, David L; Zhu, Hesun

2015-02-01

Three-dimensional (3-D) porous silk scaffolds with good biocompatibility and minimal immunogenicity show promise in a range of tissue regeneration applications. However, the challenge remains to effectively fabricate their microstructures and mechanical properties to satisfy the specific requirements of different tissues. In this study, silk scaffolds were fabricated to form an extracellular matrix (ECM) mimetic nanofibrous architecture using a mild process. A slowly increasing concentration process was applied to regulate silk self-assembly into nanofibers in aqueous solution. Then glycerol was blended with the nanofiber solution and induced silk crystallization in the lyophilization process, endowing freeze-dried scaffolds with water stability. The glycerol was leached from the scaffolds, leaving a similar porous structure at the micrometer scale but different topographies at the nanoscale. Compared to previous salt-leached and methanol-annealed scaffolds, the present scaffolds showed lower β-sheet content, softer mechanical property and improved cell growth and differentiation behaviors, suggesting their promising future as platforms for controlling stem cell fate and soft tissue regeneration. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Unified scaling behavior of physical properties of clays in alcohol solutions.

PubMed

Pujala, Ravi Kumar; Pawar, Nisha; Bohidar, H B

2011-12-15

This paper reports observation of universal scaling of physical properties of clay particles, Laponite (aspect ratio=30) (L) and Na Montmorillonite (MMT, aspect ratio=200), in aqueous alcohol solutions (methanol, ethanol and 1-propanol) with solvent polarity, defined through reaction field factor f(OH)(ɛ(0),n)=[(ɛ(0) - 1/ɛ(0) + 2) - (n(2) - 1/n(2) + 2)], at room temperature (20°C). Here, ɛ(0) and n are the static dielectric constant and refractive index of the solvent concerned. Physical properties (Z) such as zeta potential, effective aggregate size, viscosity and surface tension scaled with the relative solvent polarity as Z∼δf(α); δf=(f(w)(ɛ(0),n) - f(OH)(ɛ(0),n)), where f(w)(ɛ(0),n) is the reaction field factor for water, Z is the normalized physical property, and α is its characteristic scaling exponent. The value of this exponent was found to be invariant of aspect ratio of the clay but dependent on the solvent polarity only. Copyright © 2011 Elsevier Inc. All rights reserved.

Noble metal-free RGO/TiO2 composite nanofiber with enhanced photocatalytic H2-production performance

NASA Astrophysics Data System (ADS)

Xu, Difa; Li, Lingling; He, Rongan; Qi, Lifang; Zhang, Liuyang; Cheng, Bei

2018-03-01

1D reduced graphene oxide (RGO)/TiO2 nanocomposite fibers were fabricated by a facile two-step method. These samples demonstrated high photocatalytic H2-production activity from methanol aqueous solution, even without the aid of noble metal. When the ratio of RGO is 0.25 wt%, the highest H2-production rate was achieved. It increased by 10 fold than bare TiO2, reaching 149 μmol h-1 g-1 with quantum efficiency (QE) of 0.75%. The reasons were as follows. Firstly, the RGO nanosheets acted as electron acceptors. Secondly, some shallow trap states at the surface or interface of TiO2 were created by the reduction of GO during calcination. Thirdly, the redox potential position of graphene/graphene- was suitable. Fourthly, RGO could efficiently promote the separation of photogenerated electron-hole pairs and significantly enhance the photocatalytic H2-production activity. This interpretation was corroborated by transient photocurrent response. The aforementioned marvelous results provided a probable solution to replace noble metals (such as Pt) by graphene as an effective cocatalyst.

Adulticide effect of Monticalia greenmaniana (Asteraceae) against Lutzomyia migonei (Diptera: Psychodidae).

PubMed

Cárdenas, José; Rojas, Janne; Rondón, Maritza; Nieves, Elsa

2012-08-01

Leishmaniasis is a public health problem that has been increasing year by year, with the further difficulty that an efficient control system is not available. Therefore, it is necessary to search for less contaminating and dangerous alternatives for controlling Leishmania transmitting sandflies. The purpose of this study was to evaluate the activity of Monticalia greenmaniana (Asteraceae) extracts and essential oil as an adulticide against Lutzomyia migonei (Diptera: Psychodidae) females, from a laboratory colony, in experimental conditions. Dry aerial parts of M. greenmaniana (Hieron) Jeffrey were used. Methanolic and aqueous extracts were prepared, and essential oil was obtained by hydrodistillation. Adulticide tests in pots, adulticide tests in cages, and knocked-down effects were determined. The results obtained demonstrated that methanolic and aqueous extracts produced adulticide activity. The essential oil from M. greenmaniana was proved to be the most toxic against L. migonei, with a 95 % death rate at a concentration of 0.01 mg/ml during a 1-h exposure. The essential oil showed a DL50 = 0.0050 and DL98 = 0.0066 mg/ml. The methanolic extract was DL50 = 0.130 and DL98 = 1.016 mg/ml, and the aqueous extract, DL50 = 0.487 and DL98 10.924 mg/ml. The knocked-down effect for the M. greenmaniana oil showed a KDTL50 = 48.6 and KDTL98 = 90.1 min. It was concluded that the essential oil from M. greenmaniana showed a strong insecticide effect against L. migonei females, which encourages us to continue these studies in search for control alternatives against sandflies.

Chronic consumption of Hypericum humifusum leaf extracts impairs epididymis spermatozoa characters in association with oxidative stress in adult male Wistar rats.

PubMed

Hammami, Imen; Ali, Ridha Ben; Nahdi, Afef; Kallech-Ziri, Olfa; Boussada, Marwa; El May, Ahmed; El May, Michèle Véronique

2017-09-01

Recently, there has been increasing interest in Hypericum (Hypericaceae) genus. The first part of the present study focused on the phytochemical analysis of the methanolic and aqueous extracts of Hypericum humifusum leaves. The second part of the study investigated the effect of Hypericum humifusum leaf extracts on male reproductive parameters. 30 male rats were grouped into control (1mL/rat, distilled water), treated by 200mg/kg body weight (bw) aqueous extract (A200), 400mg/kg bw aqueous extract (A400), 10mg/kg bw methanolic extract (M10) and 20mg/kg bw methanolic extract (M20) groups. The phytochemical analysis revealed the presence of tannins, flavonoids, steroids, carbohydrates, and phenolic compounds. After thirty-day treatment, body and reproductive organs were weighed. Testes in all rat groups were processed for biochemical assays and histopathological examinations. Epididymis sperm analyses were also performed. Testicular tissue homogenate samples were used for Malondialdehyde (MDA), catalase and superoxide dismutase (SOD) measurements. We showed that Hh extracts induced a severe seminiferous tubular damage with an increase in the percentage of empty seminiferous tubules. Epididymis sperm analysis revealed a significant reduction in density and viability of sperm with alteration of spermatozoa morphology. Also, we found that Hh leaf extracts decreased plasma total cholesterol, HDL-cholesterol and triglycerides levels. These results were associated with an increase of MDA levels and a decrease of catalase and SOD activities in testis tissues. Our finding revealed that chronic consumption of Hh extracts induces disruption of normal spermatogenesis by alteration of sperm density, viability, and morphology. This action may be due to an inhibition of the antioxidant-defense system. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Discrimination and similarity evaluation of tissue-cultured and wild Dendrobium species using Fourier transform infrared spectroscopy

NASA Astrophysics Data System (ADS)

Chen, Nai-dong; Chen, Han; Li, Jun; Sang, Mang-mang; Ding, Shen; Yu, Hao

2015-04-01

The FTIR method was applied to evaluate the similarity of tissue-cultured and wild Dendrobium huoshanense C.Z. Tang et S.J. Cheng, Dendrobium officinale Kimura et Migo and Dendrobium moniliforme (Linn.) Sw and discriminate different Dendrobium species, especially D. huoshanense and its main goldbrick Dendrobium henanense J.L. Lu et L.X. Gao. Despite the general pattern of the IR spectra, different intensities, shapes and peak positions were found in the IR spectra of these samples, especially in the range of 1800-600 cm-1, which could be used to discriminate them. The methanol, aqueous extracting procedure and the second derivative transformation obviously enlarged the tiny spectral differences among these samples. The similarity evaluation based on the IR spectra and the second derivative IR spectrum revealed that the similarity of the methanol extracts between tissue-cultured and wild Dendrobiums might be lower than that between different Dendrobium species. The similarities of the powders and aqueous extracts between tissue-cultured and wild Dendrobiums were higher than those between different Dendrobium species. The further principal component analysis showed that the first three components explained 99.7%, 87.7% and 85.1% of data variance for powder, methanol extract and aqueous extract, respectively, demonstrating a good discrimination between samples. Our research suggested that the variations of secondary metabolites between different origins of the investigated Dendrobiums might be higher than what we had supposed. Tissue culture techniques were widely used in the conversation of rare and endangered medicinal amedica, however, our study suggested that the chemical constituents of tissue-cultured plants might be quite different from their wild correspondences.

Water-soluble polymers for recovery of metal ions from aqueous streams

DOEpatents

Smith, Barbara F.; Robison, Thomas W.

1998-01-01

A process of selectively separating a target metal contained in an aqueous solution by contacting the aqueous solution containing a target metal with an aqueous solution including a water-soluble polymer capable of binding with the target metal for sufficient time whereby a water-soluble polymer-target metal complex is formed, and, separating the solution including the water-soluble polymer-target metal complex from the solution is disclosed.

A one- and two-dimensional NMR study of the B to Z transition of (m5dC-dG)3 in methanolic solution.

PubMed Central

Feigon, J; Wang, A H; van der Marel, G A; Van Boom, J H; Rich, A

1984-01-01

The deoxyribose hexanucleoside pentaphosphate (m5dC-dG)3 has been studied by 500 MHz 1H NMR in D2O (0.1 M NaCl) and in D2O/deuterated methanol mixtures. Two conformations, in slow equilibrium on the NMR time scale, were detected in methanolic solution. Two-dimensional nuclear Overhauser effect (NOE) experiments were used to assign the base and many of the sugar resonances as well as to determine structural features for both conformations. The results were consistent with the an equilibrium in solution between B-DNA and Z-DNA. The majority of the molecules have a B-DNA structure in low-salt D2O and a Z-DNA structure at high methanol concentrations. A cross-strand NOE between methyl groups on adjacent cytosines is observed for Z-DNA but not B-DNA. The B-DNA conformation predominates at low methanol concentrations and is stabilized by increasing temperature, while the Z-DNA conformation predominates at high methanol concentrations and low temperatures. 31P NMR spectra gave results consistent with those obtained by 1H NMR. Comparison of the 31P spectra with those obtained on poly(dG-m5dC) allow assignment of the lower field resonances to GpC in the Z conformation. PMID:6694910

Aggregation of Cobalt (II) Tetrasulfonated Phthalocyanine in Methanol- Water Solutions

DTIC Science & Technology

1983-06-01

the presence of ethanol was measured over the same temperature range with methanol rcent mole fraction from 0.4 to 9.8. The temperature dependence...similar temperature dependence for the free energy of denaturation of proteins in ethanol -water solution. 6 5, 6 6 Since -C is proportional to AC 0 , a...8217-" -- : oi - -• solutions at various temperatures ; The-d&mýiarzation constant was determined by a nonlinear least-squares fit o absorbance versus

Mössbauer study of modified iron-molybdenum catalysts for methanol oxidation

NASA Astrophysics Data System (ADS)

Ivanov, K. I.; Mitov, I. G.; Krustev, St. V.; Boyanov, B. S.

2010-03-01

The preparation and catalytic properties of mixed Fe-Mo-W catalysts toward methanol oxidation are investigated. Mössbauer spectroscopy, X-ray diffraction and chemical studies revealed the formation of two types of solid solutions with compositions Fe2(MoxW1-xO4)3 and (MoxW1-x)O3. The solid solutions formed are characterized by high activity and selectivity upon methanol oxidation and are of interest in view of their practical application. Sodium-doped iron-molybdenum catalysts are also investigated and the NaFe(MoO4)2 formation was established.

Process for separating and recovering an anionic dye from an aqueous solution

DOEpatents

Rogers, Robin; Horwitz, E. Philip; Bond, Andrew H.

1998-01-01

A solid/liquid phase process for the separation and recovery of an anionic dye from an aqueous solution is disclosed. The solid phase comprises separation particles having surface-bonded poly(ethylene glycol) groups, whereas the aqueous solution from which the anionic dye molecules are separated contains a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved lyotropic salt. After contact between the aqueous solution and separation particles, the anionic dye is bound to the particles. The bound anionic dye molecules are freed from the separation particles by contacting the anionic dye-bound particles with an aqueous solution that does not contain a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved lyotropic salt to form an aqueous anionic dye solution whose anionic dye concentration is preferably higher than that of the initial dye-containing solution.

Determination of induction period and crystal growth mechanism of dexamethasone sodium phosphate in methanol-acetone system

NASA Astrophysics Data System (ADS)

Hao, Hongxun; Wang, Jingkang; Wang, Yongli

2005-02-01

The induction period of dexamethasone sodium phosphate at different supersaturation was experimentally determined in a methanol-acetone system. The laser monitoring observation technique was used to determine the appearance of the first nucleus in solution. The effect of solution composition on induction period was discussed. Based on classical homogeneous nucleation theory, the solid-liquid interfacial tension and surface entropy factor were calculated from the induction period data. The experimentally determined values of interfacial tension are in agreement with the theoretical values predicted by the Mersmann equation. It was found that the nucleus of dexamethasone sodium phosphate grows continuously in pure methanol and turns from continuous growth to birth and spread growth with increasing acetone content in a methanol-acetone mixture.

[Exploration on feasibility of introducing bioassay method into quality evaluation of Chinese herbal medicines by studying on the correlation between antioxidant activity of Prunella vulgaris and its total phenolic acids content for example].

PubMed

Feng, Wei-Hong; Li, Chun; Xin, Wei-Mei; Lin, Li-Mei; Xia, Bo-Hou; Rong, Li-Xin; Yang, Li-Xin; Yi, Hong; Zhang, Yong-Xin; Chen, Liang-Mian; Wang, Zhi-Min

2016-07-01

This paper aims to investigate the correlation between the antioxidant activity of Prunella vulgaris and its total phenolic acids content by measuring the antioxidant activity of different sources and different organs of P. vulgaris and the total contents of protocatechuic acid, protocatechuic aldehyde, caffeic acid, salviaflaside and rosmarinic acid in these samples. Using the 50% methanol extract of P. vulgaris samples as the research object, DPPH method and HPLC method were used respectively to determine the antioxidant activities and the total contents of the above-mentioned five analytes in P. vulgaris samples. 0.5 mL of 50% methanol extract of P. vulgaris reacts with 0.1 mmol•L⁻¹ DPPH ethanol solution for 60 min, then the absorbance of the reaction solution was measured at 517 nm, scavenging rate and IC₅₀ values were calculated by the absorbance and the sample concentration for evaluating the antioxidant activity. HPLC analysis was made on a C₁₈ Epic column, with acetonitrile-0.1% formic acid aqueous solution as mobile phase (gradient elution), and the detection wavelength was set at 280 nm. The correlation between the antioxidant capacity of different habitats and different organs of P. vulgaris and the total contents of five kinds of phenolic acids was analyzed by partial least squares method. The reaction dose-response range of 50% methanol extract of P. vulgaris with 0.1 mmol•L⁻¹ DPPH ethanol solution was 0.300-1.65 g•L⁻¹. When the quantities of potocatechuic acid, protocatechuic aldehyde, caffeic acid, salviaflaside and rosmarinic acid were respectively in 0.007 84-0.980, 0.011 5-1.44, 0.008 64-1.08, 0.080 0-1.00 and 0.079 8-0.998 μg range, their quantities were in good linear relationship with the corresponding peak areas. The average recovery of 5 components were 97.76%, 96.88%, 100.3%, 102.1%, 104.5%, with RSD of 1.8%, 1.6%, 1.7%, 1.6% and 1.7%, respectively. In a certain range of crude drug quantity, the antioxidant activity of each organ of P. vulgaris and total phenolic acids content inside has a good linear correlation. Therefore, in certain quality range of crude drug, DPPH bioassay combined with HPLC content determination can be used for the quality control of P. vulgaris, as is a new method for the quality control of P. vulgaris. Copyright© by the Chinese Pharmaceutical Association.

Antibacterial properties of some plants used in Mexican traditional medicine for the treatment of gastrointestinal disorders.

PubMed

Alanís, A D; Calzada, F; Cervantes, J A; Torres, J; Ceballos, G M

2005-08-22

Antibacterial properties of aqueous and methanolic extracts of 26 medicinal plants used in Mexico to treat gastrointestinal disorders were tested against eight different species of enteropathogens: two Escherichia coli species; two Shigella sonnei species; two Shigella flexneri species; and two Salmonella sp. species. The results showed that all crude extracts exhibited antibacterial activity, at least against one of the microorganisms tested, at concentrations of 8 mg/mL or lower. The extracts from Caesalpinia pulcherria, Chiranthodendron pentadactylon, Cocos nucifera, Geranium mexicanum (aerial parts and roots), Hippocratea excelsa, and Punica granatum possessed strong antibacterial activity against most of the pathogens tested. In general, methanolic extracts were more active than aqueous extracts. Their activity was higher than chloramphenicol but did not exceed that of trimethoprim. Shigella sonnei species showed the highest susceptibility to both extracts. This is the first evaluation of these plants against bacterial pathogen isolates, which cause diarrhea and dysentery in Mexican population.

Anti-Helicobacter pylori activity of plants used in Mexican traditional medicine for gastrointestinal disorders.

PubMed

Castillo-Juárez, Israel; González, Violeta; Jaime-Aguilar, Héctor; Martínez, Gisela; Linares, Edelmira; Bye, Robert; Romero, Irma

2009-03-18

Helicobacter pylori is the major etiological agent of chronic active gastritis and peptic ulcer disease and is linked to gastric carcinoma. Treatment to eradicate the bacteria failed in many cases, mainly due to antibiotic resistance, hence the necessity of developing better therapeutic regimens. Mexico has an enormous unexplored potential of medicinal plants. This work evaluates the in vitro anti-H. pylori activity of 53 plants used in Mexican traditional medicine for gastrointestinal disorders. To test the in vitro antibacterial activity, agar dilution and broth dilution methods were used for aqueous and methanolic extracts, respectively. Aqueous extracts of Artemisia ludoviciana subsp. mexicana, Cuphea aequipetala, Ludwigia repens,and Mentha x piperita (MIC 125 to <250 microg/ml) as well as methanolic extracts of Persea americana, Annona cherimola, Guaiacum coulteri, and Moussonia deppeana (MIC <7.5 to 15.6 microg/ml) showed the highest inhibitory effect. The results contribute to understanding the mode of action of the studied medicinal plants and for detecting plants with high anti-Helicobacter pylori activity.

Correlation of the rates of solvolysis of α-bromoisobutyrophenone using both simple and extended forms of the Grunwald-Winstein equation and the application of correlation analysis to related studies.

PubMed

Kevill, Dennis Neil; Kim, Chang-Bae; D'Souza, Malcolm John

2018-03-01

A Grunwald-Winstein treatment of the specific rates of solvolysis of α-bromoisobutyrophenone in 100% methanol and in several aqueous ethanol, methanol, acetone, 2,2,2-trifluoroethanol (TFE), and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) mixtures gives a good logarithmic correlation against a linear combination of N T (solvent nucleophilicity) and Y Br (solvent ionizing power) values. The l and m sensitivity values are compared to those previously reported for α-bromoacetophenone and to those obtained from parallel treatments of literature specific rate values for the solvolyses of several tertiary mesylates containing a C(=O)R group attached at the α-carbon. Kinetic data obtained earlier by Pasto and Sevenair for the solvolyses of the same substrate in 75% aqueous ethanol (by weight) in the presence of silver perchlorate and perchloric acid are analyzed using multiple regression analysis.

Simultaneous Separation of Manganese, Cobalt, and Nickel by the Organic-Aqueous-Aqueous Three-Phase Solvent Extraction

NASA Astrophysics Data System (ADS)

Shirayama, Sakae; Uda, Tetsuya

2016-04-01

This research outlines an organic-aqueous-aqueous three-phase solvent extraction method and proposes its use in a new metal separation process for the recycling of manganese (Mn), cobalt (Co), and nickel (Ni) from used lithium ion batteries (LIBs). The three-phase system was formed by mixing xylene organic solution, 50 pct polyethylene glycol (PEG) aqueous solution, and 1 mol L-1 sodium sulfate (Na2SO4) aqueous solution. The xylene organic solution contained 2-ethylhexylphosphonic acid (D2EHPA) as an extractant for Mn ion, and the Na2SO4 aqueous solution contained 1 mol L-1 potassium thiocyanate (KSCN) as an extractant for Co ion. Concentrations of the metal ions were varied by dissolving metal sulfates in the Na2SO4 aqueous solution. As a result of the experiments, Mn, Co, and Ni ions were distributed in the xylene organic phase, PEG-rich aqueous phase, and Na2SO4-rich aqueous phase, respectively. The separation was effective when the pH value was around 4. Numerical simulation was also conducted in order to predict the distribution of metal ions after the multi-stage counter-current extractions.

The Comparative Photodegradation Activities of Pentachlorophenol (PCP) and Polychlorinated Biphenyls (PCBs) Using UV Alone and TiO2-Derived Photocatalysts in Methanol Soil Washing Solution

PubMed Central

Zhou, Zeyu; Zhang, Yaxin; Wang, Hongtao; Chen, Tan; Lu, Wenjing

2014-01-01

Photochemical treatment is increasingly being applied to remedy environmental problems. TiO2-derived catalysts are efficiently and widely used in photodegradation applications. The efficiency of various photochemical treatments, namely, the use of UV irradiation without catalyst or with TiO2/graphene-TiO2 photodegradation methods was determined by comparing the photodegadation of two main types of hydrophobic chlorinated aromatic pollutants, namely, pentachlorophenol (PCP) and polychlorinated biphenyls (PCBs). Results show that photodegradation in methanol solution under pure UV irradiation was more efficient than that with either one of the catalysts tested, contrary to previous results in which photodegradation rates were enhanced using TiO2-derived catalysts. The effects of various factors, such as UV light illumination, addition of methanol to the solution, catalyst dosage, and the pH of the reaction mixture, were examined. The degradation pathway was deduced. The photochemical treatment in methanol soil washing solution did not benefit from the use of the catalysts tested. Pure UV irradiation was sufficient for the dechlorination and degradation of the PCP and PCBs. PMID:25254664

EMERGING TECHNOLOGY BULLETIN: REMOVAL OF PHENOL FROM AQUEOUS SOLUTIONS USING HIGH ENERGY ELECTRON BEAM IRRADIATION

EPA Science Inventory

Irradiation of aqueous solutions with high-energy electrons results in the formation of the aqueous electron, hydrogen radical, H-, and the hydroxyl radical, OH-. These reactive transient species initiate chemical reactions capable of destroying organic compounds in aqueous solut...

REMOVAL OF CHLORIDE FROM AQUEOUS SOLUTIONS

DOEpatents

Schulz, W.W.

1959-08-01

The removal of chlorides from aqueons solutions is described. The process involves contacting the aqueous chloride containing solution with a benzene solution about 0.005 M in phenyl mercuric acetate whereby the chloride anions are taken up by the organic phase and separating the organic phase from the aqueous solutions.

Methanol test

MedlinePlus

... Safety and Health. Emergency Response Safety and Health Database. Methanol: systemic agent. Updated May 28, 2015. www. ... ADAM Health Solutions. About MedlinePlus Site Map FAQs Customer Support Get email updates Subscribe to RSS Follow ...

Phytochemical screening, antioxidants and antimicrobial potential of Lantana camara in different solvents

PubMed Central

Naz, Rabia; Bano, Asghari

2013-01-01

Objective To evaluate the antioxidant activity, hydrogen peroxide radicals scavenging activity, reducing power, the total phenolic and flavonoids contents, and antimicrobial and antifungal activities of methanol, ethanol and water extracts of leaves of Lantana camara (L. camara). Methods Methanol, ethanol and water extracts were evaluated against four Gram positive and Gram negative bacterial isolates (Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Bacillus subtilis) and two fungal strains (Aspergillus fumigatus and Aspergillus flavus). Methanol extract at different concentrations was tested for antioxidant potential and phytochemicals were determined by using spectrophotometric method. Results The total phenolic content was (40.859±0.017) mg gallic acid/g in the leaves of L. camara, while the total flavonoids was (53.112±0.199) mg/g dry weight. Methanol leaf extract of L. camara showed maximum antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa and was also effective against other bacterial strains as compared to ethanol and aqueous extracts of leaves. The methanol leaf extract of L. camara exhibited significant inhibition (71%) and (66%) against Aspergillus fumigatus and Aspergillus flavus respectively. Conclusions The methanol extract of the L. camara leaves is effective against selected bacterial and fungal strains. Its phytochemical contents have broad antimicrobial properties and the plant might be a novel source of antimicrobial drug.

In vitro investigation of antimicrobial activities of ethnomedicinal plants against dental caries pathogens.

PubMed

Besra, Mamta; Kumar, Vipin

2018-05-01

The study aimed to evaluate the antimicrobial activity of medicinal plant extracts against the bacterial pathogens prominent in dental caries. A total of 20 plant species (herbs, shrubs and trees) belonging to 18 genera and 15 families were documented for dental caries. Antimicrobial activity of solvent extracts and essential oil from plants were determined by zone of inhibition on the growth of Streptococcus mutans (MTCC 497) and Lactobacillus acidophilus (MTCC 10307) using the agar well diffusion method. The results of in vitro antimicrobial assay prove that methanol is more successful in the extraction of phytochemicals from plant samples than aqueous solvent, as methanol extracts show higher antimicrobial activity than aqueous extracts against both the test pathogens. Methanol extracts of Nigella sativa, Psidium guajava and Syzygium aromaticum were the most effective among all 20 plant samples and have potent inhibitory activity against both dental caries pathogens with minimum inhibitory concentration of 0.2 mg mL - 1 . N. sativa seed methanol extract was more effective with 22.3 mm zone of inhibition at 0.2 mg mL - 1 against S. mutans (MTCC 497), while L. acidophilus (MTCC 10307) was more sensitive to S. aromaticum bud methanol extract at 11.3 mm zone of inhibition at concentration 0.1 mg mL - 1 . Essential oil extracted from plants also possesses strong antimicrobial activity for both test pathogens, with a minimum inhibitory concentration range of 0.05-0.16 mg mL - 1 . Syzygium aromaticum bud essential oil at 0.05 mg mL - 1 was most active against S. mutans (MTCC 497). Plant extracts viewing antimicrobial activity with minimum inhibitory concentration show the efficacy of the plant products that could be considered as a good indicator of prospective plants for discovering new antimicrobial agents against dental caries pathogens. The findings of this study provide a lead to further polyherbal formulations for the treatment of dental caries malaise.

Process for separating and recovering an anionic dye from an aqueous solution

DOEpatents

Rogers, R.; Horwitz, E.P.; Bond, A.H.

1998-01-13

A solid/liquid phase process for the separation and recovery of an anionic dye from an aqueous solution is disclosed. The solid phase comprises separation particles having surface-bonded poly(ethylene glycol) groups, whereas the aqueous solution from which the anionic dye molecules are separated contains a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved lyotropic salt. After contact between the aqueous solution and separation particles, the anionic dye is bound to the particles. The bound anionic dye molecules are freed from the separation particles by contacting the anionic dye-bound particles with an aqueous solution that does not contain a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved lyotropic salt to form an aqueous anionic dye solution whose anionic dye concentration is preferably higher than that of the initial dye-containing solution. 7 figs.

Phase-separable aqueous amide solutions as a thermal history indicator.

PubMed

Kitsunai, Makoto; Miyajima, Kentaro; Mikami, Yuzuru; Kim, Shokaku; Hirasawa, Akira; Chiba, Kazuhiro

2008-12-01

Aqueous solutions of several new amide compounds for use as simple thermal history indicators in the low-temperature transport of food and other products were synthesized. The phase transition temperatures of the aqueous solutions can be freely adjusted by changing the amide-water ratio in solution, the sodium chloride concentration of the water, and the type of amide compound. It is expected that these aqueous solutions can be applied as new thermal history indicators.

Effect of vacuum and of strong adsorbed water films on micropore formation in aluminum hydroxide xerogel powders.

PubMed

Beruto, Dario T; Botter, Rodolfo; Converti, Attilio

2009-02-01

Aluminum hydroxide gels were washed with water, ethanol, methanol and isopropanol to obtain new gels with different liquid phases that were dried either in air at 120 degrees C or under vacuum at 80 degrees C. Drying in air leads to alcoholic xerogels with BET surface areas larger than the aqueous ones. The effect of the alcoholic groups as substitutes of the hydroxyl ones has been discussed to account for the final size of xerogel crystallites. Drying under vacuum decreases the BET surface of the methanol xerogels, but no micropores are formed in all the alcoholic xerogel matrixes. On the contrary, the vacuum drying process changes significantly the microstructure of the aqueous xerogels. Their BET surface increases by 34 m(2)/g, and micropores are formed within their crystallite aggregates. It has been experimentally shown that these changes are due to a shear transformation that occurs in the boehmite xerogels obtained under vacuum. To discuss these data, the existence of chemical compounds such as AlOOHnH(2)O was postulated. On this ground, a neat analogy between vacuum drying process and vacuum interfacial decomposition reactions of inorganic salts can be drawn. This analogy explains how a state of stresses forms in aqueous xerogel matrix during vacuum drying process.

Wound healing potential of Spirulina platensis extracts on human dermal fibroblast cells

PubMed Central

Syarina, Pauzi Nur Aimi; Karthivashan, Govindarajan; Abas, Faridah; Arulselvan, Palanisamy; Fakurazi, Sharida

2015-01-01

Blue-green alga (Spirulina platensis) is a well renowned nutri-supplement due to its high nutritional and medicinal properties. The aim of this study was to examine the wound healing efficiency of Spirulina platensis at various solvent extracts using in vitro scratch assay on human dermal fibroblast cells (HDF). Various gradient solvent extracts (50 μg/ml of methanolic, ethanolic and aqueous extracts) from Spirulina platensis were treated on HDF cells to acquire its wound healing properties through scratch assay and in this investigation we have used allantoin, as a positive control to compare efficacy among the phytoextracts. Interestingly, aqueous extract were found to stimulate proliferation and migration of HDF cells at given concentrations and enhanced closure rate of wound area within 24 hours after treatment. Methanolic and ethanolic extracts have shown proliferative effect, however these extracts did not aid in the migration and closure of wound area when compared to aqueous extract. Based on phytochemical profile of the plant extracts analyzed by LC-MS/MS, it was shown that compounds supposedly involved in accelerating wound healing are cinnamic acid, narigenin, kaempferol, temsirolimus, phosphatidylserine isomeric derivatives and sulphoquinovosyl diacylglycerol. Our findings concluded that blue-green algae may pose potential biomedical application to treat various chronic wounds especially in diabetes mellitus patients. PMID:27004048

Antibacterial activity of Psidium guajava leaf and bark against multidrug-resistant Vibrio cholerae: implication for cholera control.

PubMed

Rahim, Niaz; Gomes, Donald James; Watanabe, Haruo; Rahman, Sabita Rizwana; Chomvarin, Chariya; Endtz, Hubert Ph; Alam, Munirul

2010-07-01

In clinical cholera, a 3-day course of antibiotic complements extensive rehydration therapy by reducing stool volume, shortening the illness, and averting death. However, antibiotic therapy, which has lifesaving implications for cholera, is often hindered due to multidrug resistance in Vibrio cholerae, the cause of cholera. Crude aqueous mixture and water soluble methanol extract from leaf and bark of Psidium guajava, a tropical fruit guava of the family Myrtaceae, showed strong antibacterial activity against multidrug-resistant V. cholerae O1. The in vitro minimum inhibitory concentration of the crude aqueous mixture and water soluble methanol extract, which was bactericidal against 10(7) CFU/mL of V. cholerae was determined to be 1,250 microg/mL and 850 microg/mL, respectively. The antibacterial activity of P. guajava was stable at 100 degrees C for 15-20 min, suggesting nonprotein nature of the active component. The growth of V. cholerae in rice oral rehydration saline (ORS) was completely inhibited when 10 mg/mL (wt/vol) of crude aqueous mixture was premixed with the ORS in a ratio of 1:7 (vol. extract/vol. ORS). P. guajava, which is widely distributed in Bangladesh, thus offers great potential for use in indigenous, herbal medicine for controlling epidemics of cholera.

Preparation and physicochemical characteristics of polylactide microspheres of emamectin benzoate by modified solvent evaporation/extraction method.

PubMed

Zhang, Shao Fei; Chen, Peng Hao; Zhang, Fei; Yang, Yan Fang; Liu, De Kun; Wu, Gang

2013-12-18

Emamectin benzoate is highly effective against insect pests and widely used in the world. However, its biological activity is limited because of high resistance of target insects and rapid degradation speed in fields. Preparation and physicochemical characterization of degradable microcapsules of emamectin benzoate were studied by modified solvent evaporation/extraction method using polylactide (PLA) as wall material. The influence of different compositions of the solvent in internal organic phase and external aqueous phase on diameter, span, pesticide loading, and entrapment rate of the microspheres was investigated. The results indicated that the process of solvent extraction and the formation of the microcapsules would be accelerated by adding water-miscible organic solvents such as ethyl ether, acetone, ethyl acetate, or n-butanol into internal organic phase and external aqueous phase. Accelerated formation of the microcapsules would result in entrapment rates of emamectin benzoate increased to as high as 97%. In addition, by adding ethanol into the external aqueous phase, diameters would reduce to 6.28 μm, whereas the loading efficiency of emamectin benzoate did not increase. The PLA microspheres prepared under optimum conditions were smoother and more spherical. The degradation rate in PLA microspheres of emamectin benzoate on the 10th day was 4.29 ± 0.74%, whereas the degradation rates of emamectin benzoate in methanol solution and solid technical material were 46.3 ± 2.11 and 22.7 ± 1.51%, respectively. The PLA skeleton had combined with emamectin benzoate in an amorphous or molecular state by using differential scanning calorimetry (DSC) determination. The results indicated that PLA microspheres of emamectin benzoate with high entrapment rate, loading efficiency, and physicochemical characteristics could be obtained by adding water-miscible organic solvents into the internal organic phase and external aqueous phase.

Physicochemical and crystal structure analyses of the antidiabetic agent troglitazone.

PubMed

Kobayashi, Katsuhiro; Fukuhara, Hiroshi; Hata, Tadashi; Sekine, Akiko; Uekusa, Hidehiro; Ohashi, Yuji

2003-07-01

The antidiabetic agent troglitazone has two asymmetric carbons located at the chroman ring and the thiazolidine ring and is produced as a mixture of equal amounts of four optical isomers, 2R-5S, 2S-5R, 2R-5R, and 2S-5S. The crystalline powdered drug substance consists of two diastereomer pairs, 2R-5R/2S-5S and 2R-5S/2S-5R. There are many types of crystals obtained from various crystallization conditions. The X-ray structure analysis and the physicochemical analyses of troglitazone were performed. The solvated crystals of the 2R-5R/2S-5S pair were crystallized from several solutions: methanol, ethanol, acetonitrile, and dichloromethane. The ratio of solvent and troglitazone was 1 : 2 (L1/2-form). The monohydrate crystals were obtained from aqueous acetone solution (L1-form). On the other hand, only an anhydrate crystal of the 2R-5S/2S-5R pair was crystallized from various solutions (H0-form). The dihydrous mixed crystal (MA2-form) was obtained from a mixture of the two diastereomer pairs of 2R-5R/2S-5S and 2R-5S/2S-5R in equal amounts by the slow evaporation of aqueous acetone solution. The crystal structure of the MA2-form is similar to the H0-form. When the MA2 crystal was kept under low humidity, it was converted into the dehydrated form (MA0-form) with retention of the single crystal form. The structure of the MA0-form is isomorphous to the H0-form. The MA2-form was converted into the MA0-form and vice versa with retention of the single crystal under low and high humidity, respectively. The crystallization and storage conditions of the drug substances were successfully analyzed.

Competitive removal of hazardous dyes from aqueous solution by MIL-68(Al): Derivative spectrophotometric method and response surface methodology approach

NASA Astrophysics Data System (ADS)

Tehrani, Mahnaz Saghanejhad; Zare-Dorabei, Rouholah

2016-05-01

MIL-68(Al) as a metal-organic framework (MOF) was synthesized and characterized by different techniques such as SEM, BET, FTIR, and XRD analysis. This material was then applied for simulations removal of malachite green (MG) and methylene blue (MB) dyes from aqueous solutions using second order derivative spectrophotometric method (SODS) which was applied to resolve the overlap between the spectra of these dyes. The dependency of dyes removal efficiency in binary solutions was examined and optimized toward various parameters including initial dye concentration, pH of the solution, adsorbent dosage and ultrasonic contact time using central composite design (CCD) under response surface methodology (RSM) approach. The optimized experimental conditions were set as pH 7.78, contact time 5 min, initial MB concentration 22 mg L- 1, initial MG concentration 12 mg L- 1 and adsorbent dosage 0.0055 g. The equilibrium data was fitted to isotherm models such as Langmuir, Freundlich and Tempkin and the results revealed the suitability of the Langmuir model. The maximum adsorption capacity of 666.67 and 153.85 mg g- 1 was obtained for MB and MG removal respectively. Kinetics data fitting to pseudo-first order, pseudo-second order and Elovich models confirmed the applicability of pseudo-second order kinetic model for description of the mechanism and adsorption rate. Dye-loaded MIL-68(Al) can be easily regenerated using methanol and applied for three frequent sorption/desorption cycles with high performance. The impact of ionic strength on removal percentage of both dyes in binary mixture was studied by using NaCl and KCl soluble salts at different concentrations. According to our findings, only small dosage of the proposed MOF is considerably capable to remove large amounts of dyes at room temperature and in very short time that is a big advantage of MIL-68(Al) as a promising adsorbent for adsorptive removal processes.

Measurement of Menadione in Urine by HPLC

PubMed Central

Rajabi, Ala Al; Peterson, James; Choi, Sang Woon; Suttie, John; Barakat, Susan; Booth, Sarah L

2010-01-01

Menadione is a metabolite of vitamin K that is excreted in urine. A high performance liquid chromatography (HPLC) method using a C30 column, post-column zinc reduction and fluorescence detection was developed to measure urinary menadione. The mobile phase was composed of 95% methanol with 0.55% aqueous solution and 5% DI H2O. Menaquinone-2 (MK-2) was used as an internal standard. The standard calibration curve was linear with a correlation coefficient (R2) of 0.999 for both menadione and MK-2. The lower limit of quantification (LLOQ) was 0.3 pmole menadione/mL urine. Sample preparation involved hydrolysis of menadiol conjugates and oxidizing the released menadiol to menadione. Using this method, urinary menadione was shown to increase in response to 3 years of phylloquinone supplementation. This HPLC method is a sensitive and reproducible way to detect menadione in urine. Research support: USDA ARS Cooperative Agreement 58-1950-7-707. PMID:20719580

Measurement of menadione in urine by HPLC.

PubMed

Al Rajabi, Ala; Peterson, James; Choi, Sang-Woon; Suttie, John; Barakat, Susan; Booth, Sarah L

2010-09-15

Menadione is a metabolite of vitamin K that is excreted in urine. A high performance liquid chromatography (HPLC) method using a C(30) column, post-column zinc reduction and fluorescence detection was developed to measure urinary menadione. The mobile phase was composed of 95% methanol with 0.55% aqueous solution and 5% DI H(2)O. Menaquinone-2 (MK-2) was used as an internal standard. The standard calibration curve was linear with a correlation coefficient (R(2)) of 0.999 for both menadione and MK-2. The lower limit of quantification (LLOQ) was 0.3pmole menadione/mL urine. Sample preparation involved hydrolysis of menadiol conjugates and oxidizing the released menadiol to menadione. Using this method, urinary menadione was shown to increase in response to 3 years of phylloquinone supplementation. This HPLC method is a sensitive and reproducible way to detect menadione in urine. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Au/ZnO nanoarchitectures with Au as both supporter and antenna of visible-light

NASA Astrophysics Data System (ADS)

Liu, Tianyu; Chen, Wei; Hua, Yuxiang; Liu, Xiaoheng

2017-01-01

In this paper, we fabricate Au/ZnO nanostructure with smaller ZnO nanoparticles loaded onto bigger gold nanoparticles via combining seed-mediated method and sol-gel method. The obtained Au/ZnO nanocomposites exhibit excellent properties in photocatalysis process like methyl orange (MO) degradation and oxidative conversion of methanol into formaldehyde under visible light irradiation. The enhanced properties were ascribed to the surface plasmon resonance (SPR) effect of Au nanoparticles, which could contribute to the separation of photo-excited electrons and holes and facilitate the process of absorbing visible light. This paper contributes to the emergence of multi-functional nanocomposites with possible applications in visible-light driven photocatalysts and makes the Au/ZnO photocatalyst an exceptional choice for practical applications such as environmental purification of organic pollutants in aqueous solution and the synthesis of fine chemicals and intermediates.

An optical material for the detection of β-hydroxybutyrate based on a terbium complex

NASA Astrophysics Data System (ADS)

Wang, Xiaomiao; Chen, Huili; Li, Hua

2014-02-01

A novel Tb3+ complex (Tb(C14H10O4)ṡCl, TbL2) based on benzoic acid (L+H) was successfully synthesized, and gave a weak green emission in methanol-water (V:V, 4:1, pH 4.49). With the addition of β-hydroxybutyrate (β-HB) to a semi-aqueous solution of TbL2, an increment of the luminescent intensity at 545 nm assigned to 5D4 → 7F5 transition of Tb3+ was measured, which was evident to the naked eye. The response showed high selectivity for β-HB compared with other common anions including Cl-, NO3-, CO32-, PO43-, HPO42-, HPO4-, CO42-, PO74-, SO42-, lactate, AcO-, citrate, malate therefore it has the potential to be applied as a luminescent sensor for β-HB.

Human Cytochrome P450 Enzyme Modulation by Gymnema sylvestre: A Predictive Safety Evaluation by LC-MS/MS

PubMed Central

Rammohan, Bera; Samit, Karmakar; Chinmoy, Das; Arup, Saha; Amit, Kundu; Ratul, Sarkar; Sanmoy, Karmakar; Dipan, Adhikari; Tuhinadri, Sen

2016-01-01

Background: Traditionally GS is used to treat diabetes mellitus. Drug-herb interaction of GS via cytochrome P450 enzyme system by substrate cocktail method using HLM has not been reported. Objective: To evaluate the in-vitro modulatory effects of GS extracts (aqueous, methanol, ethyl acetate, chloroform and n-hexane) and deacylgymnemic acid (DGA) on human CYP1A2, 2C8, 2C9, 2D6 and 3A4 activities in HLM. Material and Methods: Probe substrate-based LCMS/MS method was established for all CYPs. The metabolite formations were examined after incubation of probe substrates with HLM in the presence or absence of extracts and DGA. The inhibitory effects of GS extracts and DGA were characterized with kinetic parameters IC50 and Ki values. Results: GS extracts showed differential effect on CYP activities in the following order of inhibitory potency: ethyl acetate > Chloroform > methanol > n-hexane > aqueous > DGA. This differential effect was observed against CYP1A2, 2C9 and less on CYP3A4 and 2C8 but all CYPs were unaffected by aqueous extract and DGA. The ethyl acetate and chloroform extract exhibited moderate inhibition towards CYP1A2 and 3A4. The aqueous extract and DGA however showed negligible inhibition towards all five major human CYPs with very high IC50 values (>90μg/ml). Conclusion: The results of our study revealed that phytoconstituents contained in GS, particularly in ethyl acetate and chloroform extracts, were able to inhibit CYP1A2, 3A4 and 2C9. The presence of relatively small, lipophillic yet slightly polar compounds within the GS extracts may be attributed for inhibition activities. These suggest that the herb or its extracts should be examined for potential pharmacokinetic drug interactions in vivo. Abbreviations used: GS: Gymnema sylvestre, GSE: Gymnema sylvestre extract, DGA: deacyl gymnemic acid, CYP: cytochrome P450, DMSO: dimethylsulphoxide, HLM: human liver microsomes, LC-MS/MS: liquid chromatography tandem mass spectroscopy, NADPH: reduced nicotinamide adeninedinucleotide phosphate, NRS: nicotinamide adeninedinucleotide phosphate regenerating system, CHE: chloroform extract, EAE: ethyl acetate extract, NHE- n-hexane extract, AE: aqueous extract, ME: methanol extract PMID:27761064

LASERS, ACTIVE MEDIA: The aqueous-polyelectrolyte dye solution as an active laser medium

NASA Astrophysics Data System (ADS)

Akimov, A. I.; Saletskii, A. M.

2000-11-01

The spectral, luminescent, and lasing properties of aqueous solutions of a cationic dye rhodamine 6G with additions of anion polyelectrolytes — polyacrylic and polymethacrylic acids — are studied. It is found that the energy and spectral properties of lasing of these solutions depend on the ratio of concentrations of polyelectrolyte and molecules. It is also found that the lasing parameters of aqueous-polyelectrolyte dye solutions can be controlled by changing the structure of the molecular system. The variation in the structure of aqueous-polyelectrolyte dye solutions of rhodamine 6G resulted in an almost five-fold increase in the lasing efficiency compared to that in aqueous dye solutions.

In vitro antiprotozoal activity of the leaves of Artemisia ludoviciana.

PubMed

Said Fernández, Salvador; Ramos Guerra, Monica Celina; Mata Cárdenas, Benito David; Vargas Villarreal, Javier; Villarreal Treviño, Licet

2005-07-01

The inhabitants of Northeast of Mexico use an infusion of leaves from Artemisia ludoviciana as an antidiarrheal remedy. The aqueous, methanol, acetone and hexane leaf extracts from mature plants were found to be active in vitro against the parasitic protozoa Entamoeba histolytica and Giardia lamblia.

Solution-phase electronegativity scale: insight into the chemical behaviors of metal ions in solution.

PubMed

Li, Keyan; Li, Min; Xue, Dongfeng

2012-04-26

By incorporating the solvent effect into the Born effective radius, we have proposed an electronegativity scale of metal ions in aqueous solution with the most common oxidation states and hydration coordination numbers in terms of the effective ionic electrostatic potential. It is found that the metal ions in aqueous solution are poorer electron acceptors compared to those in the gas phase. This solution-phase electronegativity scale shows its efficiency in predicting some important properties of metal ions in aqueous solution such as the aqueous acidities of the metal ions, the stability constants of metal complexes, and the solubility product constants of the metal hydroxides. We have elaborated that the standard reduction potential and the solution-phase electronegativity are two different quantities for describing the processes of metal ions in aqueous solution to soak up electrons with different final states. This work provides a new insight into the chemical behaviors of the metal ions in aqueous solution, indicating a potential application of this electronegativity scale to the design of solution reactions.

Simultaneous determination of inorganic anions and cations by supercritical fluid chromatography using evaporative light scattering detection.

PubMed

Foulon, Catherine; Di Giulio, Pauline; Lecoeur, Marie

2018-01-26

Supercritical fluid chromatography (SFC) is commonly used for the analysis of non-polar compounds, but remains poorly explored for the separation of polar and ionized molecules. In this paper, SFC has been investigated for the separation of 14 inorganic ions sampled in aqueous solutions. Four polar stationary phases were first screened using CO 2 -methanol-based mobile phases containing water or different acidic or basic additives, in order to select the most efficient conditions for the simultaneous retention of inorganic cations and anions and to favor their detection using evaporative light scattering detector (ELSD). Orthogonal selectivity was obtained depending on the stationary phase used: whereas anions are less retained on HILIC stationary phase, 2-ethylpyridine (2-EP) stationary phase exhibits strong interaction for anions. Best results were obtained under gradient elution mode using a 2-EP stationary phase and by adding 0.2% triethylamine in the CO 2 -methanol-based mobile phase. The composition of the injection solvent was also investigated. The results showed that a methanolic sample containing a percentage of water not exceeding 20% does not affect the analytical performances obtained on 2-EP. Moreover, the presence of triethylamine in the injection solvent contributes to eliminate peaks shoulders. Among the 14 inorganic ions tested, three cations (Li + , Ca 2+ and Mg 2+ ) and five anions (Cl - , Br - , NO 3 - , I - , SCN - ) were totally resolved in 15 min. NO 3 - and NO 2 - still coeluted in the final optimized conditions. The other investigated ions were either strongly retained on the stationary phase or not detected by the ELSD. Copyright © 2017 Elsevier B.V. All rights reserved.

Phytotoxic activity and chemical composition of Cassia absus seeds and aerial parts.

PubMed

Zribi, I; Sbai, H; Ghezal, N; Richard, G; Trisman, D; Fauconnier, M L; Haouala, R

2017-12-01

The present study was conducted to assess the phytotoxic potential and the phytochemical composition of Cassia absus. Aqueous extracts caused significant reduction in root growth of Lactuca sativa. Seed extract was more effective than aerial part extract. Successive extractions of this plant were performed using solvents with increasing polarities. The methanolic seed extract exerted strong phytotoxic effect on seedling growth, followed by petroleum ether extract of the aerial part. The phytochemical investigation showed that among the organic extracts, methanol extracts of seeds and aerial parts contained the highest amounts of total phenolics and proanthocyanidins. Seeds were rich in linoleic acid followed by palmitic acids. Palmitic, stearic and arachidic acids were the major fatty acids in aerial parts. HPLC-DAD analysis of the methanolic extracts revealed the presence of luteolin in C. absus aerial parts.

Method of precipitating uranium from an aqueous solution and/or sediment

DOEpatents

Tokunaga, Tetsu K; Kim, Yongman; Wan, Jiamin

2013-08-20

A method for precipitating uranium from an aqueous solution and/or sediment comprising uranium and/or vanadium is presented. The method includes precipitating uranium as a uranyl vanadate through mixing an aqueous solution and/or sediment comprising uranium and/or vanadium and a solution comprising a monovalent or divalent cation to form the corresponding cation uranyl vanadate precipitate. The method also provides a pathway for extraction of uranium and vanadium from an aqueous solution and/or sediment.

SEPARATION OF SCANDIUM VALUES FORM IRON VALUES BY SOLVENT EXTRACTION

DOEpatents

Kuhlman, C.W. Jr.; Lang, G.P.

1961-12-19

A process is given for separating scandium from trivalent iron values. In this process, an aqueous nitric acid solution is contacted with a water- immiscible alkyl phosphate solution, the aqueous solution containing the values to be separated, whereby the scandium is taken up by the alkyl phosphate. The aqueous so1ution is preferably saturated with magnesium nitrate to retain the iron in the aqueous solution. (AEC)

Modification of the surface adsorption properties of alumina-supported Pd catalysts for the electrocatalytic hydrogenation of phenol.

PubMed

Cirtiu, Ciprian Mihai; Hassani, Hicham Oudghiri; Bouchard, Nicolas-Alexandre; Rowntree, Paul A; Ménard, Hugues

2006-07-04

The electrocatalytic hydrogenation (ECH) of phenol has been studied using palladium supported on gamma-alumina (10% Pd-Al2O3) catalysts. The catalyst powders were suspended in aqueous supporting electrolyte solutions containing methanol and short-chain aliphatic acids (acetic acid, propionic acid, or butyric acid) and were dynamically circulated through a reticulated vitreous carbon cathode. The efficiency of the hydrogenation process was measured as a function of the total electrolytic charge and was compared for different types of supporting electrolyte and for various solvent compositions. Our results show that these experimental parameters strongly affect the overall ECH efficiency of phenol. The ECH efficiency and yields vary inversely with the quantity of methanol present in the electrolytic solutions, whereas the presence of aliphatic carboxylic acids increased the ECH efficiency in proportion to the chain length of the specific acids employed. In all cases, ECH efficiency was directly correlated with the adsorption properties of phenol onto the Pd-alumina catalyst in the studied electrolyte solution, as measured independently using dynamic adsorption isotherms. It is shown that the alumina surface binds the aliphatic acids via the carboxylate terminations and transforms the catalyst into an organically functionalized material. Temperature-programmed mass spectrometry analysis and diffuse-reflectance infrared spectroscopy measurements confirm that the organic acids are stably bound to the alumina surface below 200 degrees C, with coverages that are independent of the acid chain length. These reproducibly functionalized alumina surfaces control the adsorption/desorption equilibrium of the target phenol molecules and allow us to prepare new electrocatalytic materials to enhance the efficiency of the ECH process. The in situ grafting of specific aliphatic acids on general purpose Pd-alumina catalysts offers a new and flexible mechanism to control the ECH process to enhance the selectivity, efficiency, and yields according to the properties of the specific target molecule.

Evolution of Spatial pH Distribution in Aqueous Solution induced by Atmospheric Pressure Plasma

NASA Astrophysics Data System (ADS)

Takahashi, Shigenori; Mano, Kakeru; Hayashi, Yui; Takada, Noriharu; Kanda, Hideki; Goto, Motonobu

2016-09-01

Discharge plasma at gas-liquid interface produces some active species, and then they affect chemical reactions in aqueous solution, where pH of aqueous solution is changed due to redox species. The pH change of aqueous solution is an important factor for chemical reactions. However, spatial pH distribution in a reactor during the discharge has not been clarified yet. Thus, this work focused on spatial pH distribution of aqueous solution when pulsed discharge plasma was generated from a copper electrode in gas phase to aqueous solution in a reactor. Experiments were conducted using positive unipolar pulsed power. The unipolar pulsed voltage at +8.0 kV was applied to the copper electrode and the bottom of the reactor was grounded. The size of the reactor was 80 mm wide, 10 mm deep, and 40 mm high. The electrode was set at distance of 2 mm from the solution surface. Anthocyanins were contained in the aqueous solution as a pH indicator. The change pH solution spread horizontally, and low pH region of 10 mm in depth was formed. After discharge for 10 minutes, the low pH region was diffused toward the bottom of the reactor. After discharge for 60 minutes, the pH of the whole solution decreased.

Hydrogen production by sodium borohydride in NaOH aqueous solution

NASA Astrophysics Data System (ADS)

Wang, Q.; Zhang, L. F.; Zhao, Z. G.

2018-01-01

The kinetics of hydrolysis reaction of NaBH4 in NaOH aqueous solution is studied. The influence of pH of the NaOH aqueous solution on the rate of hydrogen production and the hydrogen production efficiency are studied for the hydrolysis reaction of NaBH4. The results show that the activation energy of hydrolysis reaction of NaBH4 increased with the increase of the initial pH of NaOH aqueous solution.With the increasing of the initial pH of NaOH aqueous solution, the rate of hydrogen production and hydrogen production efficiency of NaBH4 hydrolysis decrease.

Assessment of Fenton's reagent and ozonation as pre-treatments for increasing the biodegradability of aqueous diethanolamine solutions from an oil refinery gas sweetening process.

PubMed

Durán-Moreno, A; García-González, S A; Gutiérrez-Lara, M R; Rigas, F; Ramírez-Zamora, R M

2011-02-28

The aim of this work was to evaluate the efficiency of three chemical oxidation processes for increasing the biodegradability of aqueous diethanolamine solutions (aqueous DEA solutions), to be used as pre-treatments before a biological process. The raw aqueous DEA solution, sourced from a sour gas sweetening plant at a Mexican oil refinery, was first characterized by standardized physico-chemical methods. Then experiments were conducted on diluted aqueous DEA solutions to test the effects of Fenton's reagent, ozone and ozone-hydrogen peroxide on the removal of some physicochemical parameters of these solutions. Lastly, biodegradability tests based on Dissolved Organic Carbon Die Away OECD301-A, were carried out on a dilution of the raw aqueous DEA solution and on the treated aqueous DEA solutions, produced by applying the best experimental conditions determined during the aforementioned oxidation tests. Experimental results showed that for aqueous DEA solutions treated with Fenton's reagent, the best degradation rate (70%) was obtained at pH 2.8, with Fe(2+) and H(2)O(2) at doses of 1000 and 10,000 mg/L respectively. In the ozone process, the best degradation (60%) was observed in aqueous DEA solution (100 mg COD/L), using 100 mg O(3)/L at pH 5. In the ozone-hydrogen peroxide process, no COD or DOC removals were observed. The diluted spent diethanolamine solution showed its greatest increase in biodegradability after a reaction period of 28 days when treated with Fenton's reagent, but after only 15 days in the case of ozonation. Copyright © 2011 Elsevier B.V. All rights reserved.

A simple method to separate red wine nonpolymeric and polymeric phenols by solid-phase extraction.

PubMed

Pinelo, Manuel; Laurie, V Felipe; Waterhouse, Andrew L

2006-04-19

Simple polyphenols and tannins differ in the way that they contribute to the organoleptic profile of wine and their effects on human health. Very few straightforward techniques to separate red wine nonpolymeric phenols from the polymeric fraction are available in the literature. In general, they are complex, time-consuming, and generate large amounts of waste. In this procedure, the separation of these compounds was achieved using C18 cartridges, three solvents with different elution strengths, and pH adjustments of the experimental matrices. Two full factorial 2(3) experimental designs were performed to find the optimal critical variables and their values, allowing for the maximization of tannin recovery and separation efficiency (SE). Nonpolymeric phenols such as phenolic acids, monomers, and oligomers of flavonol and flavan-3-ols and anthocyanins were removed from the column by means of an aqueous solvent followed by ethyl acetate. The polymeric fraction was then eluted with a combination of methanol/acetone/water. The best results were attained with 1 mL of wine sample, a 10% methanol/water solution (first eluant), ethyl acetate (second eluant), and 66% acetone/water as the polymeric phenols-eluting solution (third eluant), obtaining a SE of ca. 90%. Trials with this method on fruit juices also showed high separation efficiency. Hence, this solid-phase extraction method has been shown to be a simple and efficient alternative for the separation of nonpolymeric phenolic fractions and the polymeric ones, and this method could have important applications to sample purification prior to biological testing due to the nonspecific binding of polymeric phenolics to nearly all enzymes and receptor sites.

Cryo-irradiation as a terminal method for the sterilization of drug aqueous solutions.

PubMed

Maquille, Aubert; Habib Jiwan, Jean-Louis; Tilquin, Bernard

2008-05-01

The aim of this study is to evaluate the specificities of the irradiation of drugs in frozen aqueous solution. The structures of the degradation products were determined to gain insight into the radiolysis mechanisms occurring in frozen aqueous solutions. Metoclopramide hydrochloride and metoprolol tartrate were chosen as models. The frozen solutions were irradiated at dry ice temperature by high energy electrons at various doses. The drug purity (chemical potency) and the radiolysis products were quantified by HPLC-DAD. Characterization of the degradation products was performed by LC-APCI-MS-MS. The structures of the radiolysis products detected in irradiated frozen aqueous solutions were compared to those detected in solid-state and aqueous solutions (previous studies). For both metoclopramide and metoprolol, solute loss upon irradiation of frozen aqueous solutions was negligible. Five radiolysis products present in traces were identified in irradiated metoclopramide frozen solutions. Three of them were previously identified in solid-state irradiated metoclopramide crystals. The two others were formed following reactions with the hydroxyl radical (indirect effect). Only one fragmentation product was observed in irradiated metoprolol frozen solutions. For both drugs, radiosterilization of frozen solutions, even at high doses (25 kGy), was found to be possible.

Adulticidal, repellent, and ovicidal properties of indigenous plant extracts against the malarial vector, Anopheles stephensi (Diptera: Culicidae).

PubMed

Panneerselvam, Chellasamy; Murugan, Kadarkarai

2013-02-01

Mosquito-borne diseases with an economic impact create loss in commercial and labor outputs, particularly in countries with tropical and subtropical climates. Mosquito control is facing a threat because of the emergence of resistance to synthetic insecticides. Extracts from plants may be alternative sources of mosquito control agents because they constitute a rich source of bioactive compounds that are biodegradable into nontoxic products and potentially suitable for use to control mosquitoes. Insecticides of botanical origin may serve as suitable alternative biocontrol techniques in the future. In view of the recently increased interest in developing plant origin insecticides as an alternative to chemical insecticide, this study was undertaken to assess the adulticidal, repellent, and ovicidal potential of the crude hexane, ethyl acetate, benzene, aqueous, and methanol solvent extracts from the medicinal plants Andrographis paniculata, Cassia occidentalis, and Euphorbia hirta against the medically important mosquito vector, Anopheles stephensi (Diptera: Culicidae).The adult mortality was observed after 24 h of exposure. All extracts showed moderate adulticide effects; however, the highest adult mortality was found in methanol extract of A. paniculata followed by C. occidentalis and E. hirta against the adults of A. stephensi with LC(50) and LC(90) values of 210.30, 225.91, and 263.91 ppm and 527.31, 586.36, and 621.91 ppm, respectively. The results of the repellent activity of hexane, ethyl acetate, benzene, aqueous, and methanol extract of A. paniculata, C. occidentalis, and E. hirta plants at three different concentrations of 1.0, 3.0, and 6.0 mg/cm(2) were applied on skin of forearm in man and exposed against adult female mosquitoes. In this observation, these three plant crude extracts gave protection against mosquito bites without any allergic reaction to the test person, and also, the repellent activity is dependent on the strength of the plant extracts. Mean percent hatchability of the ovicidal activity was observed 48 h post-treatment. The percent hatchability was inversely proportional to the concentration of extract and directly proportional to the eggs. Mortality of 100 % with methanol extract of A. paniculata exerted at 150 ppm and aqueous, methanol extract of C. occidentalis and E. hirta were exerted at 300 ppm. These results suggest that the leaf extracts of A. paniculata, C. occidentalis, and E. hirta have the potential to be used as an ideal eco-friendly approach for the control of the A. stephensi. Further detailed research is needed to identify the active ingredient in the extracts and implement the effective mosquito management program.

Variance in the chemical composition of dry beans determined from UV spectral fingerprints

USDA-ARS?s Scientific Manuscript database

Nine varieties of dry beans representing 5 market classes were grown in 3 states (Maryland, Michigan, and Nebraska) and sub-samples were collected for each variety (row composites from each plot). Aqueous methanol extracts were analyzed in triplicate by UV spectrophotometry. Analysis of variance-p...

Noble metal superparticles and methods of preparation thereof

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

Sun, Yugang; Hu, Yongxing

A method comprises heating an aqueous solution of colloidal silver particles. A soluble noble metal halide salt is added to the aqueous solution which undergoes a redox reaction on a surface of the silver particles to form noble metal/silver halide SPs, noble metal halide/silver halide SPs or noble metal oxide/silver halide SPs on the surface of the silver particles. The heat is maintained for a predetermined time to consume the silver particles and release the noble metal/silver halide SPs, the noble metal halide/silver halide SPs or the noble metal oxide/silver halide SPs into the aqueous solution. The aqueous solution ismore » cooled. The noble metal/silver halide SPs, the noble metal halide/silver halide SPs or noble metal oxide/silver halide SPs are separated from the aqueous solution. The method optionally includes adding a soluble halide salt to the aqueous solution.« less

Hydrogen generation systems utilizing sodium silicide and sodium silica gel materials

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

Wallace, Andrew P.; Melack, John M.; Lefenfeld, Michael

Systems, devices, and methods combine reactant materials and aqueous solutions to generate hydrogen. The reactant materials can sodium silicide or sodium silica gel. The hydrogen generation devices are used in fuels cells and other industrial applications. One system combines cooling, pumping, water storage, and other devices to sense and control reactions between reactant materials and aqueous solutions to generate hydrogen. Multiple inlets of varied placement geometries deliver aqueous solution to the reaction. The reactant materials and aqueous solution are churned to control the state of the reaction. The aqueous solution can be recycled and returned to the reaction. One systemmore » operates over a range of temperatures and pressures and includes a hydrogen separator, a heat removal mechanism, and state of reaction control devices. The systems, devices, and methods of generating hydrogen provide thermally stable solids, near-instant reaction with the aqueous solutions, and a non-toxic liquid by-product.« less

Hydrogen generation systems utilizing sodium silicide and sodium silica gel materials

DOEpatents

Wallace, Andrew P.; Melack, John M.; Lefenfeld, Michael

2015-07-14

Systems, devices, and methods combine reactant materials and aqueous solutions to generate hydrogen. The reactant materials can sodium silicide or sodium silica gel. The hydrogen generation devices are used in fuels cells and other industrial applications. One system combines cooling, pumping, water storage, and other devices to sense and control reactions between reactant materials and aqueous solutions to generate hydrogen. Multiple inlets of varied placement geometries deliver aqueous solution to the reaction. The reactant materials and aqueous solution are churned to control the state of the reaction. The aqueous solution can be recycled and returned to the reaction. One system operates over a range of temperatures and pressures and includes a hydrogen separator, a heat removal mechanism, and state of reaction control devices. The systems, devices, and methods of generating hydrogen provide thermally stable solids, near-instant reaction with the aqueous solutions, and a non-toxic liquid by-product.

Effect of methanol on the liquefaction reaction of biomass in hot compressed water under microwave energy

Treesearch

Junming Xu; Jianchun Jiang; Chun-Yun Hse; Todd F. Shupe

2013-01-01

Liquefaction of sawdust was studied in methanol-water solutions using an acid catalyst under microwave energy. The effect of the methanol concentration on the changes of components in the liquefied products was analyzed by gas chromatography−mass spectrometry (GC−MS). It was found that 5-hydroxymethylfurfural (HMF) and levulinic acid are the...

Technical and economical evaluation of carbon dioxide capture and conversion to methanol process

NASA Astrophysics Data System (ADS)

Putra, Aditya Anugerah; Juwari, Handogo, Renanto

2017-05-01

Phenomenon of global warming, which is indicated by increasing of earth's surface temperature, is caused by high level of greenhouse gases level in the atmosphere. Carbon dioxide, which increases year by year because of high demand of energy, gives the largest contribution in greenhouse gases. One of the most applied solution to mitigate carbon dioxide level is post-combustion carbon capture technology. Although the technology can absorb up to 90% of carbon dioxide produced, some worries occur that captured carbon dioxide that is stored underground will be released over time. Utilizing captured carbon dioxide could be a promising solution. Captured carbon dioxide can be converted into more valuable material, such as methanol. This research will evaluate the conversion process of captured carbon dioxide to methanol, technically and economically. From the research, it is found that technically methanol can be made from captured carbon dioxide. Product gives 25.6905 kg/s flow with 99.69% purity of methanol. Economical evaluation of the whole conversion process shows that the process is economically feasible. The capture and conversion process needs 176,101,157.69 per year for total annual cost and can be overcome by revenue gained from methanol product sales.

Development of electrodes for the NASA iron/chromium

NASA Technical Reports Server (NTRS)

Swette, L.; Jalan, V.

1984-01-01

This program was directed primarily to the development of the negative (Cr3+/Cr2+) electrode for the NASA chromous/ferric Redox battery. The investigation of the effects of substrate processing and gold/lead catalyzation parameters on electrochemical performance were continued. In addition, the effects of reactant cross-mixing, acidity level, and temperature were examined for both Redox couples. Finally, the performance of optimized electrodes was tested in system hardware (1/3 square foot single cell). The major findings are discussed: (1) The recommended processing temperature for the carbon felt, as a substrate for the negative electrode, is 1650 to 1750 C, (2) The recommended gold catalyzation procedure is essentially the published NASA procedure (NASA TM-82724, Nov. 1981) based on deposition from aqueous methanol solution, with the imposition of a few controls such as temperature (25 C) and precatalyzation pH of the felt (7), (3) Experimental observations of the gold catalyzation process and subsequent electron microscopy indicate that the gold is deposited from the colloidal state, induced by contact of the solution with the carbon felt, (4) Electrodeposited lead appears to be present as a thin uniform layer over the entire surface of the carbon fibers, rather than an discrete particles, and (5) Cross-mixing of reactants (Fe-2+ in negative electrode solution or Cr-3+ in the positive electrode solution) did not appear to produce significant interference at either electrode.

Dispersive liquid-liquid microextraction of copper ions as neocuproine complex in environmental aqueous samples.

PubMed

Shariati, Shahab; Golshekan, Mostafa

2011-06-01

In the present study, a simple and efficient extraction method based on dispersive liquid-liquid microextraction prior to UV-Vis spectrophotometry was developed for the preconcentration and determination of copper ions in environmental samples. Briefly, cupric ions (Cu II) were reduced to cuprous (Cu I) with addition of hydroxyl amine hydrochloride and formed hydrophobic chelates with neocuproine. Then, a proper mixture of acetonitrile (as dispersive solvent) and choloroform (as extraction solvent) was rapidly injected into the solution and a cloudy solution was formed. After centrifuging, choloroform was sedimented at the bottom of a conical tube and diluted with 100 µL of methanol for further UV-Vis spectrophotometry measurement. An orthogonal array design (OAD) was employed to study the effects of different parameters on the extraction efficiency. Under the optimum experimental conditions, a preconcentration factor up to 63.6 was achieved for extraction from 5.0 mL of sample solution. The limit of detection (LOD) based on S/N = 3 was 0.33 µg L-1 and the calibration curve was linear in the range of 1-200 µg L-1 with reasonable linearity (r2 > 0.997). Finally, the accuracy of the proposed method was successfully evaluated by determination of trace amounts of copper ions in different water samples and satisfactory results were obtained.

A new solid-phase extraction disk based on a sheet of single-walled carbon nanotubes.

PubMed

Niu, Hong Yun; Cai, Ya Qi; Shi, Ya Li; Wei, Fu Sheng; Liu, Jie Min; Jiang, Gui Bin

2008-11-01

A new kind of solid-phase extraction disk based on a sheet of single-walled carbon nanotubes (SWCNTs) is developed in this study. The properties of such disks are tested, and different disks showed satisfactory reproducibility. One liter of aqueous solution can pass through the disk within 10-100 min while still allowing good recoveries. Two disks (DD-disk) can be stacked to enrich phthalate esters, bisphenol A (BPA), 4-n-nonylphenol (4-NP), 4-tert-octylphenol (4-OP) and chlorophenols from various volumes of solution. The results show that SWCNT disks have high extraction ability for all analytes. The SWCNT disk can extract polar chlorophenols more efficiently than a C(18) disk from water solution. Unlike the activated carbon disk, analytes adsorbed by the new disks can be eluted completely with 8-15 mL of methanol or acetonitrile. Finally, the DD-disk system is used to pretreat 1000-mL real-world water samples spiked with BPA, 4-OP and 4-NP. Detection limits of 7, 25, and 38 ng L(-1) for BPA, 4-OP, and 4-NP, respectively, were achieved under optimized conditions. The advantages of this new disk include its strong adsorption ability, its high flow rate and its easy preparation.

Conversion of depleted uranium hexafluoride to a solid uranium compound

DOEpatents

Rothman, Alan B.; Graczyk, Donald G.; Essling, Alice M.; Horwitz, E. Philip

2001-01-01

A process for converting UF.sub.6 to a solid uranium compound such as UO.sub.2 and CaF. The UF.sub.6 vapor form is contacted with an aqueous solution of NH.sub.4 OH at a pH greater than 7 to precipitate at least some solid uranium values as a solid leaving an aqueous solution containing NH.sub.4 OH and NH.sub.4 F and remaining uranium values. The solid uranium values are separated from the aqueous solution of NH.sub.4 OH and NH.sub.4 F and remaining uranium values which is then diluted with additional water precipitating more uranium values as a solid leaving trace quantities of uranium in a dilute aqueous solution. The dilute aqueous solution is contacted with an ion-exchange resin to remove substantially all the uranium values from the dilute aqueous solution. The dilute solution being contacted with Ca(OH).sub.2 to precipitate CaF.sub.2 leaving dilute NH.sub.4 OH.

SEPARATION OF RUTHENIUM FROM AQUEOUS SOLUTIONS

DOEpatents

Beederman, M.; Vogler, S.; Hyman, H.H.

1959-07-14

The separation of rathenium from a rathenium containing aqueous solution is described. The separation is accomplished by adding sodium nitrite, silver nitrate and ozone to the ruthenium containing aqueous solution to form ruthenium tetroxide and ihen volatilizing off the ruthenium tetroxide.

SEPARATION OF POLONIUM, PROTACTINIUM OR MIXTURES THEREOF IN AQUEOUS SOLUTION FROM BISMUTH, LEAD, ZIRCONIUM AND/OR COLUMBIUM VALUES

DOEpatents

Van Winkle, Q.; Kraus, K.A.

1959-10-27

A process is presented for separating polonium, protactinium, or mixtures thereof in aqueous solution from bismuth, zirconium, lead, and niobium values contained in the solution. The method comprises providing hydrochloric acid in the solution in a concentration of at least 5N. contacting the aqueous solution with a substantially waterimmiscible organic solvent such as diisopropyl ketone, and separating the aqueous phase containing the bismuth, zirconium, lead, and niobium from the organic extract phase containing the polonium, protactinium, or mixture thereof.

Ionic liquids as silica deactivating agents in gas chromatography for direct analysis of primary amines in water.

PubMed

Krzyżaniak, Agnieszka; Weggemans, Wilko; Schuur, Boelo; de Haan, André B

2011-12-16

Analysis of primary amines in aqueous samples remains a challenging analytical issue. The preferred approach by gas chromatography is hampered by interactions of free silanol groups with the highly reactive amine groups, resulting in inconsistent measurements. Here, we report a method for direct analysis of aliphatic amines and diamines in aqueous samples by gas chromatography (GC) with silanol deactivation using ionic liquids (ILs). ILs including trihexyl(tetradecyl)phosphonium bis 2,4,4-(trimethylpentyl)phosphinate (Cyphos IL-104), 1-methyl-3-propylimidazolium bis(trifluoromethylsulfonyl)imide [pmim][Tf(2)N] and N″-ethyl-N,N,N',N'-tetramethylguanidinium tris(pentafluoroethyl)trifluorophosphate [etmg][FAP] were tested as deactivating media for the GC liner. Solutions of these ILs in methanol were injected in the system prior to the analysis of primary amines. Butane-1,4-diamine (putrescine, BDA) was used as a reference amine. The best results were obtained using the imidazolium IL [pmim][Tf(2)N]. With this deactivator, excellent reproducibility of the analysis was achieved, and the detection limit of BDA was as low as 1mM. The applicability of the method was proven for the analysis of two different primary amines (C4-C5) and pentane-1,5-diamine. Copyright © 2011 Elsevier B.V. All rights reserved.

Free Radical Scavenging Fingerprints of Selected Aromatic and Medicinal Tunisian Plants Assessed by Means of TLC-DPPH(•) Test and Image Processing.

PubMed

El Euch, Salma Kammoun; Cieśla, Łukasz; Bouzouita, Nabiha

2014-01-01

Aqueous-methanol extracts prepared from 10 Tunisian plant species were analyzed for the presence of potent direct antioxidants. The analyzed species included: Anacyclus clavatus Desf., Erica multiflora L., Cistus salvifolius L., Centaurium erythraea Rafn., Marrubium vulgare L., Lavandula stoechas L., Artemisia campestris L., Origanum majorana L., Salvia officinalis L., and Pistacia lentiscus L. All the extracts were chromatographed on the RP18 W plates with methanol-water-acetic acid (48 + 47 + 5, v/v/v) mobile phase. Upon completion of the chromatographic development and the drying step, the plates were stained with a chloroform solution of 2, 2-diphenyl-1-picrylhydrazyl radical (DPPH(•)). An image processing protocol, with use of Sorbfil TLC Videodensitometer, was applied to quantitatively measure the activity of polyphenols and to screen complex samples for the presence of free radical scavengers. The activity of the individual compounds was compared with that of rutin, used as a standard. The TLC-DPPH(•) test showed that C. salvifolius had the most potent antioxidant activity, as it possessed the highest activity coefficient (calculated as the sum of the areas under the peaks of all active compounds/area under peak of rutin). The proposed procedure may be used to differentiate potent chain-breaking antioxidants and compounds propagating radical chain reactions.

RECOVERY OF ACTINIDES FROM AQUEOUS NITRIC ACID SOLUTIONS

DOEpatents

Ader, M.

1963-11-19

A process of recovering actinides is presented. Tetravalent actinides are extracted from rare earths in an aqueous nitric acid solution with a ketone and back-extracted from the ketone into an aqueous medium. The aqueous actinide solution thus obtained, prior to concentration by boiling, is sparged with steam to reduce its ketone to a maximum content of 3 grams per liter. (AEC)

Overloaded elution band profiles of ionizable compounds in reversed-phase liquid chromatography: Influence of the competition between the neutral and the ionic species

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

Gritti, Fabrice; Guiochon, Georges A

2008-01-01

The parameters that affect the shape of the band profiles of acido-basic compounds under moderately overloaded conditions (sample size less than 500 nmol for a conventional column) in RPLC are discussed. Only analytes that have a single pK{sub a} are considered. In the buffer mobile phase used for their elution, their dissociation may, under certain conditions, cause a significant pH perturbation during the passage of the band. Two consecutive injections (3.3 and 10 {micro}L) of each one of three sample solutions (0.5, 5, and 50 mM) of ten compounds were injected on five C{sub 18}-bonded packing materials, including the 5more » {micro}m Xterra-C{sub 18} (121 {angstrom}), 5 {micro}m Gemini-C{sub 18} (110 {angstrom}), 5 {micro}m Luna-C{sub 18}(2) (93 {angstrom}), 3.5 {micro}m Extend-C{sub 18} (80 {angstrom}), and 2.7 {micro}m Halo-C{sub 18} (90 {angstrom}). The mobile phase was an aqueous solution of methanol buffered at a constant {sub W}{sup W}pH of 6, with a phosphate buffer. The total concentration of the phosphate groups was constant at 50 mM. The methanol concentration was adjusted to keep all the retention factors between 1 and 10. The compounds injected were phenol, caffeine, 3-phenyl 1-propanol, 2-phenyl butyric acid, amphetamine, aniline, benzylamine, p-toluidine, procainamidium chloride, and propranololium chloride. Depending on the relative values of the analyte pK{sub a} and the buffer solution pH, these analytes elute as the neutral, the cationic, or the anionic species. The influence of structural parameters such as the charge, the size, and the hydrophobicity of the analytes on the shape of its overloaded band profile is discussed. Simple but general rules predict these shapes. An original adsorption model is proposed that accounts for the unusual peak shapes observed when the analyte is partially dissociated in the buffer solution during its elution.« less

ENGINEERING BULLETIN: AIR STRIPPING OF AQUEOUS SOLUTIONS

EPA Science Inventory

Air striding is a means to transfer contaminants from aqueous solutions to air. ontaminants are not destroyed by air stripping but are physically separated from the aqueous solutions. ontaminant vapors are transferred into the air stream and, if necessary, can be treated by incin...

Nickel as a catalyst for the electro-oxidation of methanol in alkaline medium

NASA Astrophysics Data System (ADS)

Abdel Rahim, M. A.; Abdel Hameed, R. M.; Khalil, M. W.

The use of Ni as a catalyst for the electro-oxidation of methanol in alkaline medium was studied by cyclic voltammetry. It was found that only Ni dispersed on graphite shows a catalytic activity towards methanol oxidation but massive Ni does not. Ni was dispersed on graphite by the electro-deposition from acidic NiSO 4 solution using potentiostatic and galvanostatic techniques. The catalytic activity of the C/Ni electrodes towards methanol oxidation was found to vary with the amount of electro-deposited Ni. The dependence of the oxidation current on methanol concentration and scan rate was discussed. It was concluded from the electro-chemical measurements and SEM analysis that methanol oxidation starts as Ni-oxide is formed on the electrode surface.

Ethnobotanical, phytochemical and toxicological studies of Xanthium strumarium L.

PubMed

Islam, Mohammad Rashedul; Uddin, Mohammad Zashim; Rahman, Mohammad Sharifur; Tutul, Ershad; Rahman, Mohammed Zakiur; Hassan, Md Abul; Faiz, M A; Hossain, Moazzem; Hussain, Maleeha; Rashid, Mohammad Abdur

2009-12-01

The present study describes the ethnobotanical, phytochemical, and toxicological evaluations of Xanthium strumarium L. growing in Bangladesh. In toxicity evaluation on rats, the methanol extract of seedlings showed mortality, while both seedling and mature plant extracts raised the serum alanine transaminase and aspartate transaminase values and produced significant abnormalities in the histopathology of liver and kidney of rats. On the other hand, the aqueous soluble fraction of methanol extract of mature plant (LC50 = 0.352 microg/mL) and methanol crude extract of seedlings (LC50 = 0.656 microg/mL) demonstrated significant toxicity in the brine shrimp lethality bioassay. A total of four compounds were purified and characterized as stigmasterol (1), 11-hydroxy-11-carboxy-4-oxo-1(5),2(Z)-xanthadien-12,8-olide (2), daucosterol (3) and lasidiol-10-anisate (4). The present study suggests that X. strumarium is toxic to animal.

Metal separations using aqueous biphasic partitioning systems

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

Chaiko, D.J.; Zaslavsky, B.; Rollins, A.N.

1996-05-01

Aqueous biphasic extraction (ABE) processes offer the potential for low-cost, highly selective separations. This countercurrent extraction technique involves selective partitioning of either dissolved solutes or ultrafine particulates between two immiscible aqueous phases. The extraction systems that the authors have studied are generated by combining an aqueous salt solution with an aqueous polymer solution. They have examined a wide range of applications for ABE, including the treatment of solid and liquid nuclear wastes, decontamination of soils, and processing of mineral ores. They have also conducted fundamental studies of solution microstructure using small angle neutron scattering (SANS). In this report they reviewmore » the physicochemical fundamentals of aqueous biphase formation and discuss the development and scaleup of ABE processes for environmental remediation.« less

Pectinesterase inhibitor from jelly-fig (Ficus awkeotsang Makino) achenes reduces methanol content in carambola wine.

PubMed

Wu, James Swi-Bea; Wu, Ming-Chang; Jiang, Chii-Ming; Hwang, Ya-Ping; Shen, Szu-Chuan; Chang, Hung-Min

2005-11-30

Crude pectinesterase (PE) inhibitor (PEI) extracted from jelly-fig achenes (JFA) (Ficus awakeosang Makino) was added to carambola (Averrhoa carambola L.) puree to determine the change in methanol production during fermentation. Addition of pectin or microbial pectic enzyme to puree increased dose-dependently the methanol content in fermented products. Decreasing ratio (from 1:0 to 1:19, v:v) of pectic enzyme to diluted crude PEI solution in the puree-enzyme mixture decreased the PE activity remarkably. Except for transmittance (%T), addition of crude PEI to puree did not affect apparently the physical and chemical properties of wine; however, it reduced methanol content in the control from 256 to 58 ppm. The degree of esterification (DE) of pectin in starting puree was approximately 70%. It decreased to approximately 27% in the control group and reduced slightly to approximately 67% in fermented puree with crude PEI added after 14 days of fermentation. This reveals that crude PEI solution was potent in inhibiting intrinsic carambola PE activity and appeared to be a potential alternative for methanol reduction in wines.

Theoretical prediction of pKa in methanol: testing SM8 and SMD models for carboxylic acids, phenols, and amines.

PubMed

Miguel, Elizabeth L M; Silva, Poliana L; Pliego, Josefredo R

2014-05-29

Methanol is a widely used solvent for chemical reactions and has solvation properties similar to those of water. However, the performance of continuum solvation models in this solvent has not been tested yet. In this report, we have investigated the performance of the SM8 and SMD models for pKa prediction of 26 carboxylic acids, 24 phenols, and 23 amines in methanol. The gas phase contribution was included at the X3LYP/TZVPP+diff//X3LYP/DZV+P(d) level. Using the proton exchange reaction with acetic acid, phenol, and ammonia as reference species leads to RMS error in the range of 1.4 to 3.6 pKa units. This finding suggests that the performance of the continuum models for methanol is similar to that found for aqueous solvent. Application of simple empirical correction through a linear equation leads to accurate pKa prediction, with uncertainty less than 0.8 units with the SM8 method. Testing with the less expensive PBE1PBE/6-311+G** method results in a slight improvement in the results.

Raman spectroscopic study of the conformation of dicarboxylic acid salts in aqueous solutions

NASA Astrophysics Data System (ADS)

Fukushima, Kunio; Watanabe, Toshiaki; Umemura, Matome

1986-08-01

It is already known that the molecules of long chain monocarboxylic acid salts have a tendency to form micelles in aqueous solutions, the molecular chain taking the all- trans zigzag structure. However it is considered difficult for dicarboxylic acid salts to adopt the same structure as the monocarboxylic acid salts as they have two carboxyl groups, one on each end of the molecular chain. Therefore, a special structure is expected to exist for dicarboxylic acid salts in aqueous solution. In order to examine this, Raman spectra of suberic acid salt and azelaic acid salt in aqueous solution were measured and the normal vibrational calculation carried out, showing that dicarboxylic acid salts have a helical structure in aqueous solution.

SOLVENT EXTRACTION PROCESS FOR SEPARATING ACTINIDE AND LANTHANIDE METAL VALUES

DOEpatents

Hildebrandt, R.A.; Hyman, H.H.; Vogler, S.

1962-08-14

A process of countercurrently extracting an aqueous mineral acid feed solution for the separation of actinides from lanthanides dissolved therern is described. The feed solution is made acid-defrcient with alkali metal hydroxide prior to.contact with acid extractant; during extraction, however, acid is transferred from organic to aqueous solution and the aqueous solution gradually becomes acid. The acid-deficient phase ' of the process promotes the extraction of the actinides, while the latter acid phase'' of the process improves retention of the lanthanides in the aqueous solution. This provides for an improved separation. (AEC)

Measurements of thermodynamic and optical properties of selected aqueous organic and organic-inorganic mixtures of atmospheric relevance.

PubMed

Lienhard, Daniel M; Bones, David L; Zuend, Andreas; Krieger, Ulrich K; Reid, Jonathan P; Peter, Thomas

2012-10-11

Atmospheric aerosol particles can exhibit liquid solution concentrations supersaturated with respect to the dissolved organic and inorganic species and supercooled with respect to ice. In this study, thermodynamic and optical properties of sub- and supersaturated aqueous solutions of atmospheric interest are presented. The density, refractive index, water activity, ice melting temperatures, and homogeneous ice freezing temperatures of binary aqueous solutions containing L(+)-tartaric acid, tannic acid, and levoglucosan and ternary aqueous solutions containing levoglucosan and one of the salts NH(4)HSO(4), (NH(4))(2)SO(4), and NH(4)NO(3) have been measured in the supersaturated concentration range for the first time. In addition, the density and refractive index of binary aqueous citric acid and raffinose solutions and the glass transition temperatures of binary aqueous L(+)-tartaric acid and levoglucosan solutions have been measured. The data presented here are derived from experiments on single levitated microdroplets and bulk solutions and should find application in thermodynamic and atmospheric aerosol models as well as in food science applications.

Aqueous Plasma Pharmacy: Preparation Methods, Chemistry, and Therapeutic Applications

PubMed Central

Joslin, Jessica M.; McCall, James R.; Bzdek, Justin P.; Johnson, Derek C.; Hybertson, Brooks M.

2017-01-01

Plasma pharmacy is a subset of the broader field of plasma medicine. Although not strictly defined, the term aqueous plasma pharmacy (APP) is used to refer to the generation and distribution of reactive plasma-generated species in an aqueous solution followed by subsequent administration for therapeutic benefits. APP attempts to harness the therapeutic effects of plasma-generated oxidant species within aqueous solution in various applications, such as disinfectant solutions, cell proliferation related to wound healing, and cancer treatment. The subsequent use of plasma-generated solutions in the APP approach facilitates the delivery of reactive plasma species to internal locations within the body. Although significant efforts in the field of plasma medicine have concentrated on employing direct plasma plume exposure to cells or tissues, here we focus specifically on plasma discharge in aqueous solution to render the solution biologically active for subsequent application. Methods of plasma discharge in solution are reviewed, along with aqueous plasma chemistry and the applications for APP. The future of the field also is discussed regarding necessary research efforts that will enable commercialization for clinical deployment. PMID:28428835

3-Dimensional Computational Fluid Dynamics Modeling of Solid Oxide Fuel Cell Using Different Fuels

DTIC Science & Technology

2011-01-01

major types of fuel cells in practice are listed below: Polymer Electrolyte Membrane Fuel Cell ( PEMFC ) Alkaline Fuel cell (AFC) Phosphoric Acid...Material Operating Temperature (oC) Efficiency (%) PEMFC H2, Methanol, Formic Acid Hydrated Organic Polymer < 90 40-50 AFC Pure H2 Aqueous

Carica papaya (Papaya) latex: a new paradigm to combat against dengue and filariasis vectors Aedes aegypti and Culex quinquefasciatus (Diptera: Culicidae).

PubMed

Chandrasekaran, Rajkuberan; Seetharaman, Prabukumar; Krishnan, Muthukumar; Gnanasekar, Sathishkumar; Sivaperumal, Sivaramakrishnan

2018-02-01

This study manifests the larvicidal efficacy of Carica papaya latex extract and silver nanoparticles (CPAgNPs) synthesized using latex, against developing immature juveniles of Aedes aegypti and Culex quinquefasciatus . Briefly, the latex was collected and fractioned with different solvents such as chloroform, methanol and aqueously. The obtained crude extracts were subjected to larvicidal activity in the dose-dependent method. After 24 h, the mortality rate was calculated and statistically analyzed. From the results, it was demonstrated that the chloroform extract displayed prominent activity in IInd and IIIrd instar larvae of A. aegypti and C. quinquefasciatus with better LC 50 values followed by methanol and aqueous extract. Subsequently, we profiled the qualitative analysis of a chloroform extract through biochemical tests; Fourier transform infrared spectroscopy and gas chromatography-mass spectrometry. Moreover, we authenticated the major secondary metabolites and activated larvicidal compound present in the extract. Further, we synthesized CPAgNPs using aqueous latex extract and challenged with IInd and IIIrd instar larvae of A. aegypti and C. quinquefasciatus. Noticeably, the synthesized nanoproducts were showed 100% mortality in a 24-h treatment with significant LC 50 values. Hence, this study has opened up new vistas in the field of parasitological research to develop Carica papaya latex as a new stratagem in the insect vector management program.

Isolation and identification of a phytotoxic substance from the emergent macrophyte Centrostachys aquatica.

PubMed

Bich, Tran Thi Ngoc; Kato-Noguchi, Hisashi

2014-12-01

Centrostachys aquatica is a perennial emergent macrophyte in marshy places and in rivers. The species was recorded in Senegal and Nigeria, but widespread in tropical Africa, and South and East Asia. Aqueous methanol extracts C. aquatica was found to be toxic to several plant species. However, no phytotoxic substance has been reported in this species. Therefore, we investigated phytotoxic activity and searched for phytotoxic substances with allelopathic activity in C. aquatica. An aqueous methanol extract of C. aquatica inhibited the growth of roots and hypocotyls of cress (Lepidium sativum). The extract was then purified by several chromatographic runs and a phytotoxic substance with allelopathic activity was isolated and identified by spectral analysis as loliolide. Loliolide inhibited cress root and hypocotyl growth at concentrations greater than 0.03 μM. The concentrations required for 50% growth inhibition of cress roots and hypocotyls was 0.18 and 0.15 μM, respectively. These results suggest that loliolide is a phytotoxic substance and may contribute to the allelopathic effect caused by C. aquatica.

[Tricholoma equestre--animal toxicity study].

PubMed

Chodorowski, Zygmunt; Sznitowska, Małgorzata; Wiśniewski, Marek; Sein Anand, Jacek; Waldman, Wojciech; Ronikier, Anna

2004-01-01

Animal toxicity study of Tricholoma equestre mushrooms stored for 12 months at (-)20 degrees C was performed using 30 male BALB/c mice. Three groups of 5 mice each were given suspension of T. equestre powder in water, boiled aqueous extract and chloroform-methanol extract dissolved in Miglyol 812 by gavage for three consecutive days. Mice in control groups were given water, Miglyol 812 and p-phenylenediamine (CAS 106-50-3). Creatine kinase activity was determined in serum collected 72 hours after the final dose. Mean activity of serum creatine kinase in mice treated with T. equestre powder, aqueous extract, chloroform-methanol extract and Miglyol 812 were 157 +/- 93, 129 +/- 30, 96 +/- 38, 111 +/- 66 U/L respectively and did not differ significantly from mean activity in mice which were given water (107 +/- 38 U/L). Mean serum creatine kinase activity in p-phenylenediamine group (265 +/- 63 U/L) was significantly higher than in group treated with water (p<0.01). Extracts of Tricholoma equestre mushrooms stored for 12 months at (-)20 degrees C did not cause rhabdomyolysis in male BALB/c mice.

Preliminary screening of some traditional Zulu medicinal plants for antineoplastic activities versus the HepG2 cell line.

PubMed

Opoku, A R; Geheeb-Keller, M; Lin, J; Terblanche, S E; Hutchings, A; Chuturgoon, A; Pillay, D

2000-11-01

Aqueous and methanol extracts of nine traditional Zulu medicinal plants, Cissus quandrangularis L., Cyphostemma flaviflorum (Sprague) Descoings, Cyphostemma lanigerum (Harv.) Descoings ex Wild & Drum, Cyphostemma natalitium (Szyszyl.) J. v. d. Merwe, Cyphostemma sp., Rhoicissus digitata (L. F.) Gilg & Brandt, Rhoicissus rhomboidea (E. Mey. Ex harv.) Planch, Rhoicissus tomentosa (Lam.) Wild & Drum, R. tridentata (L. F.) Wild & Drum and Rhoicissus tridentata (L. F.) Wild & Drum subsp. cuneifolia (Eckl. & Zeyh.) N. R. Urton, all belonging to the Vitaceae family, were evaluated to determine their therapeutic potentials as antineoplastic agents. The antiproliferative activity in vitro against HepG2 cells was determined. Twenty-two of the twenty-seven crude plant extracts showed activities ranging from 25% to 97% inhibition of proliferation when compared with the control which showed no inhibitory activity. Higher degrees of growth inhibition were found in aqueous root extracts in comparison with the methanol extracts of the same plant parts. The results show potential antineoplastic activity, indicating some scientific validation for traditional usage. Copyright 2000 John Wiley & Sons, Ltd.

Photoproduction of hydroxyl radicals in aqueous solution with algae under high-pressure mercury lamp.

PubMed

Liu, Xianli; Wu, Feng; Deng, Nansheng

2004-01-01

Photoproduction of hydroxyl radicals (*OH) could be induced in aqueous solution with algae (Nitzschia hantzschiana, etc.) and (or not) Fe3+ under high-pressure mercury lamp with an exposure time of 4 h. *OH was determined by HPLC using benzene as a probe. The photoproduction of *OH increased with increasing algae concentration. Fe3+ could enhance the photoproduction of *OH in aqueous solution with algae. The results showed that the photoproduction of *OH in algal solution with Fe3+ was greater than that in algal solution without Fe3+. The light intensity and pH affected the photoproduction of *OH in aqueous solution with algae with/without Fe3+. The photoproduction of *OH in aqueous solution with algae and Fe3+ under 250 W was greater than that under 125 W HPML. The photoproduction of *OH in algal solution (pH ranged from 4.0 to 7.0) with (or not) Fe3+ at pH 4 was the greatest.

Germanium films by polymer-assisted deposition

DOEpatents

Jia, Quanxi; Burrell, Anthony K.; Bauer, Eve; Ronning, Filip; McCleskey, Thomas Mark; Zou, Guifu

2013-01-15

Highly ordered Ge films are prepared directly on single crystal Si substrates by applying an aqueous coating solution having Ge-bound polymer onto the substrate and then heating in a hydrogen-containing atmosphere. A coating solution was prepared by mixing water, a germanium compound, ethylenediaminetetraacetic acid, and polyethyleneimine to form a first aqueous solution and then subjecting the first aqueous solution to ultrafiltration.

High-temperature passive direct methanol fuel cells operating with concentrated fuels

NASA Astrophysics Data System (ADS)

Zhao, Xuxin; Yuan, Wenxiang; Wu, Qixing; Sun, Hongyuan; Luo, Zhongkuan; Fu, Huide

2015-01-01

Conventionally, passive direct methanol fuel cells (DMFC) are fed with diluted methanol solutions and can hardly be operated at elevated temperatures (>120 °C) because the ionic conductivity of Nafion-type proton exchange membranes depends strongly on water content. Such a system design would limit its energy density and power density in mobile applications. In this communication, a passive vapor feed DMFC capable of operating with concentrated fuels at high temperatures is reported. The passive DMFC proposed in this work consists of a fuel reservoir, a perforated silicone sheet, a vapor chamber, two current collectors and a membrane electrode assembly (MEA) based on a phosphoric acid doped polybenzimidazole (PBI) membrane. The experimental results reveal that the methanol crossover through a PBI membrane is substantially low when compared with the Nafion membranes and the PBI-based passive DMFC can yield a peak power density of 37.2 mW cm-2 and 22.1 mW cm-2 at 180 °C when 16 M methanol solutions and neat methanol are used respectively. In addition, the 132 h discharge test indicates that the performance of this new DMFC is quite stable and no obvious performance degradation is observed after activation, showing its promising applications in portable power sources.

In-situ suspended aggregate microextraction of gold nanoparticles from water samples and determination by electrothermal atomic absorption spectrometry.

PubMed

Choleva, Tatiana G; Kappi, Foteini A; Tsogas, George Z; Vlessidis, Athanasios G; Giokas, Dimosthenis L

2016-05-01

This work describes a new method for the extraction and determination of gold nanoparticles in environmental samples by means of in-situ suspended aggregate microextraction and electrothermal atomic absorption spectrometry. The method relies on the in-situ formation of a supramolecular aggregate phase through ion-association between a cationic surfactant and a benzene sulfonic acid derivative. Gold nanoparticles are physically entrapped into the aggregate phase which is separated from the bulk aqueous solution by vacuum filtration on the surface of a cellulose filter in the form of a thin film. The film is removed from the filter surface and is dissociated into an acidified methanolic solution which is used for analysis. Under the optimized experimental conditions, gold nanoparticles can be efficiently extracted from water samples with recovery rates between 81.0-93.3%, precision 5.4-12.0% and detection limits as low as 75femtomolL(-1) using only 20mL of sample volume. The satisfactory analytical features of the method along with the simplicity indicate the efficiency of this new approach to adequately collect and extract gold nanoparticle species from water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Adsorption and removal of phthalic acid and diethyl phthalate from water with zeolitic imidazolate and metal-organic frameworks.

PubMed

Khan, Nazmul Abedin; Jung, Beom K; Hasan, Zubair; Jhung, Sung Hwa

2015-01-23

ZIF-8 (zinc-methylimidazolate framework-8), one of the zeolitic imidazolate frameworks (ZIFs), has been used for the removal of phthalic acid (H2-PA) and diethyl phthalate (DEP) from aqueous solutions via adsorption. The adsorption capacity of the ZIF-8 for H2-PA was much higher than that of a commercial activated carbon or other typical metal-organic frameworks (MOFs). Because the surface area and pore volume of the adsorbents showed no favorable effect on the adsorption of H2-PA, the remarkable adsorption with ZIF-8 suggests a specific favorable interaction (electrostatic interaction) between the positively charged surface of ZIF-8 and the negatively charged PA anions. In addition, acid-base interactions also have a favorable contribution in the adsorption of H2-PA, based on the adsorptive performances of pristine and amino-functionalized MOFs and adsorption over ZIF-8 at acidic condition (pH=3.5). The reusability of ZIF-8 was also demonstrated after simple washing with methanol. On the other hand, ZIF-8 was not effective in adsorbing DEP probably because of little charge of DEP in a water solution. Copyright © 2014 Elsevier B.V. All rights reserved.

A selective electrocatalyst–based direct methanol fuel cell operated at high concentrations of methanol

PubMed Central

Feng, Yan; Liu, Hui; Yang, Jun

2017-01-01

Owing to the serious crossover of methanol from the anode to the cathode through the polymer electrolyte membrane, direct methanol fuel cells (DMFCs) usually use dilute methanol solutions as fuel. However, the use of high-concentration methanol is highly demanded to improve the energy density of a DMFC system. Instead of the conventional strategies (for example, improving the fuel-feed system, membrane development, modification of electrode, and water management), we demonstrate the use of selective electrocatalysts to run a DMFC at high concentrations of methanol. In particular, at an operating temperature of 80°C, the as-fabricated DMFC with core-shell-shell Au@Ag2S@Pt nanocomposites at the anode and core-shell Au@Pd nanoparticles at the cathode produces a maximum power density of 89.7 mW cm−2 at a methanol feed concentration of 10 M and maintains good performance at a methanol concentration of up to 15 M. The high selectivity of the electrocatalysts achieved through structural construction accounts for the successful operation of the DMFC at high concentrations of methanol. PMID:28695199

A selective electrocatalyst-based direct methanol fuel cell operated at high concentrations of methanol.

PubMed

Feng, Yan; Liu, Hui; Yang, Jun

2017-06-01

Owing to the serious crossover of methanol from the anode to the cathode through the polymer electrolyte membrane, direct methanol fuel cells (DMFCs) usually use dilute methanol solutions as fuel. However, the use of high-concentration methanol is highly demanded to improve the energy density of a DMFC system. Instead of the conventional strategies (for example, improving the fuel-feed system, membrane development, modification of electrode, and water management), we demonstrate the use of selective electrocatalysts to run a DMFC at high concentrations of methanol. In particular, at an operating temperature of 80°C, the as-fabricated DMFC with core-shell-shell Au@Ag 2 S@Pt nanocomposites at the anode and core-shell Au@Pd nanoparticles at the cathode produces a maximum power density of 89.7 mW cm -2 at a methanol feed concentration of 10 M and maintains good performance at a methanol concentration of up to 15 M. The high selectivity of the electrocatalysts achieved through structural construction accounts for the successful operation of the DMFC at high concentrations of methanol.

Tested Demonstrations. Color, Solubility, and Complex Ion Equilibria of Nickel (II) Species in Aqueous Solution.

ERIC Educational Resources Information Center

Gilbert, George L., Ed.; And Others

1980-01-01

Presents three different procedures in which reagents are added in a specified order to a large beaker containing an aqueous solution of nickel sulfate. Complex ions of nickel (II) are prepared by using aqueous solutions of ammonia, ethylenediamine, dimethylglyoxime, and cyanide ion. (CS)

Process for recovering chaotropic anions from an aqueous solution also containing other ions

DOEpatents

Rogers, Robin; Horwitz, E. Philip; Bond, Andrew H.

1999-01-01

A solid/liquid process for the separation and recovery of chaotropic anions from an aqueous solution is disclosed. The solid support comprises separation particles having surface-bonded poly(ethylene glycol) groups, whereas the aqueous solution from which the chaotropic anions are separated contains a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved salt (lyotrope). A solid/liquid phase admixture of separation particles containing bound chaotropic anions in such an aqueous solution is also contemplated, as is a chromatography apparatus containing that solid/liquid phase admixture.

Process for recovering chaotropic anions from an aqueous solution also containing other ions

DOEpatents

Rogers, R.; Horwitz, E.P.; Bond, A.H.

1999-03-30

A solid/liquid process for the separation and recovery of chaotropic anions from an aqueous solution is disclosed. The solid support comprises separation particles having surface-bonded poly(ethylene glycol) groups, whereas the aqueous solution from which the chaotropic anions are separated contains a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved salt (lyotrope). A solid/liquid phase admixture of separation particles containing bound chaotropic anions in such an aqueous solution is also contemplated, as is a chromatography apparatus containing that solid/liquid phase admixture. 19 figs.

Multi-level Quantum Mechanics and Molecular Mechanics Study of Ring Opening Process of Guanine Damage by Hydroxyl Radical in Aqueous Solution.

PubMed

Liu, Peng; Wang, Qiong; Niu, Meixing; Wang, Dunyou

2017-08-10

Combining multi-level quantum mechanics theories and molecular mechanics with an explicit water model, we investigated the ring opening process of guanine damage by hydroxyl radical in aqueous solution. The detailed, atomic-level ring-opening mechanism along the reaction pathway was revealed in aqueous solution at the CCSD(T)/MM levels of theory. The potentials of mean force in aqueous solution were calculated at both the DFT/MM and CCSD(T)/MM levels of the theory. Our study found that the aqueous solution has a significant effect on this reaction in solution. In particular, by comparing the geometries of the stationary points between in gas phase and in aqueous solution, we found that the aqueous solution has a tremendous impact on the torsion angles much more than on the bond lengths and bending angles. Our calculated free-energy barrier height 31.6 kcal/mol at the CCSD(T)/MM level of theory agrees well with the one obtained based on gas-phase reaction profile and free energies of solvation. In addition, the reaction path in gas phase was also mapped using multi-level quantum mechanics theories, which shows a reaction barrier at 19.2 kcal/mol at the CCSD(T) level of theory, agreeing very well with a recent ab initio calculation result at 20.8 kcal/mol.

In vivo wound healing activity and phytochemical screening of the crude extract and various fractions of Kalanchoe petitiana A. Rich (Crassulaceae) leaves in mice.

PubMed

Mekonnen, Awol; Sidamo, Temesgen; Asres, Kaleab; Engidawork, Ephrem

2013-01-30

The leaves of Kalanchoe petitiana A. Rich (Crassulaceae) are used in Ethiopian folk medicine for treatment of evil eye, fractured surface for bone setting and several skin disorders including for the treatment of sores, boils, and malignant wounds. In order to scientifically prove the claimed utilization of the plant, the effects of the extracts and the fractions were investigated using in vivo excision, incision and dead space wound models. Mice were used for wound healing study, while rats and rabbit were used for skin irritation test. For studying healing activity 80% methanolic extract and the fractions were formulated in strength of 5% and 10%, either as ointment (hydroalcoholic extract, aqueous and methanol fractions) or gel (chloroform fraction). Oral administration of the crude extract was used for dead space model. Negative controls were treated either with simple ointment or sodium carboxyl methyl cellulose xerogel, while positive controls with nitrofurazone (0.2 w/v) skin ointment. Negative controls for dead space model were treated with 1% carboxy methyl cellulose. Parameters, including rate of wound contraction, period of complete epithelializtion, hydroxyproline contents and skin breaking strength were evaluated. Significant wound healing activity was observed with ointment formulated from the crude extract at both 5% and 10% concentration (p<0.01) compared to controls in both excision and incision models. In dead space model, 600 mg/kg (p<0.01) but not 300 mg/kg significantly increased hydroxyproline content. Fractions showed variable effect, with the chloroform fraction lacking any significant effect. Both 5% and 10% formulations of the aqueous and methanolic fractions significantly increased wound contraction, decreased epithelializtion time and increased hydroxyproline content in excision wound model (p<0.05) as compared to controls. These fractions were also endowed with higher skin breaking strength in incision wound model (p<0.01). The present study provided evidence that the leaves of Kalanchoe petitiana A. Rich possess remarkable wound healing activities supporting the folkloric assertion of the plant. Fractionation revealed that polar or semi polar compound may play vital role, as both aqueous and methanolic fractions were endowed with wound healing activity. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Method for Non-Invasive Determination of Chemical Properties of Aqueous Solutions

NASA Technical Reports Server (NTRS)

Jones, Alan (Inventor); Thomas, Nathan A. (Inventor); Todd, Paul W. (Inventor)

2016-01-01

A method for non-invasively determining a chemical property of an aqueous solution is provided. The method provides the steps of providing a colored solute having a light absorbance spectrum and transmitting light through the colored solute at two different wavelengths. The method further provides the steps of measuring light absorbance of the colored solute at the two different transmitted light wavelengths, and comparing the light absorbance of the colored solute at the two different wavelengths to determine a chemical property of an aqueous solution.

Absorption and fluorescence emission spectroscopic characters of naphtho-homologated yy-DNA bases and effect of methanol solution and base pairing.

PubMed

Zhang, Laibin; Li, Huifang; Li, Jilai; Chen, Xiaohua; Bu, Yuxiang

2010-03-01

A comprehensive theoretical study of electronic transitions of naphtho-homologated base analogs, namely, yy-T, yy-C, yy-A, and yy-G, was performed. The nature of the low-lying excited states is discussed, and the results are compared with those from experiment and also with those of y-bases. Geometrical characteristics of the lowest excited singlet pipi* and npi* states were explored using the CIS method, and the effects of methanol solution and paring with their complementary natural bases on the relevant absorption and emission spectra of these modified bases were examined. The calculated excitation and emission energies agree well with the measured data, where experimental results are available. In methanol solution, the fluorescence from yy-A and yy-G would be expected to occur around 539 and 562 nm, respectively, suggesting that yy-A is a green-colored fluorophore, whereas yy-G is a yellow-colored fluorophore. The methanol solution was found to red-shift both the absorption and emission maxima of yy-A, yy-T, and yy-C, but blue-shift those for yy-G. Generally, though base pairing has no significant effects on the absorption and fluorescence maxima of yy-A, yy-C, and yy-T, it blue-shifts those for yy-G. (c) 2009 Wiley Periodicals, Inc.

Vasorelaxant effects of Brillantaisia nitens Lindau (Acanthaceae) extracts on isolated rat vascular smooth muscle.

PubMed

Dimo, T; Mtopi, O-S Bopda; Nguelefack, T B; Kamtchouing, P; Zapfack, L; Asongalem, E A; Dongo, E

2007-04-20

Brillantaisia nitens Lindau (Acanthaceae) is traditionally used in Cameroon for the treatment of many diseases including cardiovascular disorders. We have studied its vasorelaxant effects in rat vascular smooth muscle. In this study, aqueous, methylene chloride, methanol, and methylene chloride/methanol leaves extracts of Brillantaisia nitens were tested for their relaxing ability in vitro. Strips of rat aorta, with or without intact endothelium, were mounted in tissue baths, contracted with KCl (60mM) or norepinephrine (10(-4)M), and then exposed to the plant extracts. These extracts exhibited concentration-dependent vasorelaxations of norepinephrine-induced contractions of intact aortic strips. The EC(50) were 0.42+/-0.01mg/ml (aqueous extract), 0.63+/-0.02mg/ml (methylene chloride extract), 0.73+/-0.02mg/ml (methanol extract) and 0.36+/-0.02mg/ml (methylene chloride/methanol extract). The methylene chloride/methanol (CH(2)Cl(2)/CH(3)OH) extract was the most potent relaxing extract. It caused a concentration-dependent and endothelium-independent relaxation of the rat aortic strips contracted by KCl or norepinephrine. On the NE-induced contraction, its maximal relaxant activity (109%) due to the dose of 1.5mg/ml, was not significantly modified by the pretreatment of aortic strips with indomethacin (89%, P>0.05) or with l-NAME (103%, P>0.05). This suggests that the vasorelaxation elicited by CH(2)Cl(2)/CH(3)OH extract was not mediated via endothelium-derived prostacyclin or nitric oxide. In contrast, this relaxation was markedly reduced by tetraethylammonium, a blocker of non-selective K(+) channels and glibenclamide, a blocker of ATP-sensitive K(+) channels. The CH(2)Cl(2)/CH(3)OH extract significantly inhibited Ca(2+)-induced concentration-contraction and the Ca(2+) influx in aortic strips incubated with 60mM KCl. These results indicate that the vasorelaxant effect of the CH(2)Cl(2)/CH(3)OH extract of Brillantaisia nitens is due to an inhibition of Ca(2+) influx, possibly via the activation of ATP-sensitive K(+) channels.

Characteristics of regenerated nanocellulosic fibers from cellulose dissolution in aqueous solutions for wood fiber/polypropylene composites

Treesearch

Sangyeob Lee; Hui Pan; Chung Y. Hse; Alfred R. Gunasekaran; Todd F. Shupe

2014-01-01

The effects of aqueous solutions were evaluated on the properties of regenerated cellulosic nanofibers prepared from pure cellulose fibers in various formulations of aqueous solutions. Thermoplastic composites were prepared with reinforcement of the regenerated cellulosic nanofibers. The regenerated cellulosic fibers from cellulosic woody biomass were obtained from...

URANIUM SEPARATION PROCESS

DOEpatents

McVey, W.H.; Reas, W.H.

1959-03-10

The separation of uranium from an aqueous solution containing a water soluble uranyl salt is described. The process involves adding an alkali thiocyanate to the aqueous solution, contacting the resulting solution with methyl isobutyl ketons and separating the resulting aqueous and organic phase. The uranium is extracted in the organic phase as UO/sub 2/(SCN)/sub/.

SFG study of methanol dissociative adsorption at Pt(1 0 0), Pt(1 1 0) and Pt(1 1 1) electrodes surfaces

NASA Astrophysics Data System (ADS)

Vidal, F.; Busson, B.; Six, C.; Pluchery, O.; Tadjeddine, A.

2002-04-01

The Pt( hkl)/methanol in acidic solution interface which constitutes a model of the anodic part of a fuel cell is studied by infrared-visible sum frequency generation vibrational spectroscopy. Methanol dissociative adsorption leads to CO poisoning of the Pt electrode surfaces. The structure of the CO/Pt( hkl) interface depends strongly on the orientation of the surface electrode.

SEPARATION OF RUTHENIUM FROM AQUEOUS SOLUTIONS

DOEpatents

Callis, C.F.; Moore, R.L.

1959-09-01

>The separation of ruthenium from aqueous solutions containing uranium plutonium, ruthenium, and fission products is described. The separation is accomplished by providing a nitric acid solution of plutonium, uranium, ruthenium, and fission products, oxidizing plutonium to the hexavalent state with sodium dichromate, contacting the solution with a water-immiscible organic solvent, such as hexone, to extract plutonyl, uranyl, ruthenium, and fission products, reducing with sodium ferrite the plutonyl in the solvent phase to trivalent plutonium, reextracting from the solvent phase the trivalent plutonium, ruthenium, and some fission products with an aqueous solution containing a salting out agent, introducing ozone into the aqueous acid solution to oxidize plutonium to the hexavalent state and ruthenium to ruthenium tetraoxide, and volatizing off the ruthenium tetraoxide.

SE-72/AS-72 generator system based on Se extraction/ As reextraction

DOEpatents

Fassbender, Michael Ernst; Ballard, Beau D

2013-09-10

The preparation of a .sup.72Se/.sup.72As radioisotope generator involves forming an acidic aqueous solution of an irradiated alkali bromide target such as a NaBr target, oxidizing soluble bromide in the solution to elemental bromine, removing the elemental bromine, evaporating the resulting solution to a residue, removing hydrogen chloride from the residue, forming an acidic aqueous solution of the residue, adding a chelator that selectively forms a chelation complex with selenium, and extracting the chelation complex from the acidic aqueous solution into an organic phase. As the .sup.72Se generates .sup.72As in the organic phase, the .sup.72As may be extracted repeatedly from the organic phase with an aqueous acid solution.

Methods and systems for utilizing carbide lime or slag

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

Devenney, Martin; Fernandez, Miguel; Chen, Irvin

Provided herein are methods comprising a) treating a slag solid or carbide lime suspension with an ammonium salt in water to produce an aqueous solution comprising calcium salt, ammonium salt, and solids; b) contacting the aqueous solution with carbon dioxide from an industrial process under one or more precipitation conditions to produce a precipitation material comprising calcium carbonate and a supernatant aqueous solution wherein the precipitation material and the supernatant aqueous solution comprise residual ammonium salt; and c) removing and optionally recovering ammonia and/or ammonium salt using one or more steps of (i) recovering a gas exhaust stream comprising ammoniamore » during the treating and/or the contacting step; (ii) recovering the residual ammonium salt from the supernatant aqueous solution; and (iii) removing and optionally recovering the residual ammonium salt from the precipitation material.« less

Unique role of ionic liquid [bmin][BF 4] during curcumin-surfactant association and micellization of cationic, anionic and non-ionic surfactant solutions

NASA Astrophysics Data System (ADS)

Patra, Digambara; Barakat, Christelle

2011-09-01

Hydrophilic ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroburate, modified the properties of aqueous surfactant solutions associated with curcumin. Because of potential pharmaceutical applications as an antioxidant, anti-inflammatory and anti-carcinogenic agent, curcumin has received ample attention as potential drug. The interaction of curcumin with various charged aqueous surfactant solutions showed it exists in deprotonated enol form in surfactant solutions. The nitro and hydroxyl groups of o-nitrophenol interact with the carbonyl and hydroxyl groups of the enol form of curcumin by forming ground state complex through hydrogen bonds and offered interesting information about the nature of the interactions between the aqueous surfactant solutions and curcumin depending on charge of head group of the surfactant. IL[bmin][BF 4] encouraged early formation of micelle in case of cationic and anionic aqueous surfactant solutions, but slightly prolonged micelle formation in the case of neutral aqueous surfactant solution. However, for curcumin IL [bmin][BF 4] favored strong association (7-fold increase) with neutral surfactant solution, marginally supported association with anionic surfactant solution and discouraged (˜2-fold decrease) association with cationic surfactant solution.

Antimicrobial study of bark from five tree species.

PubMed

Pérez G, S; Zavala S, M A; Arias G, L; Pérez G, C; Pérez G, R M

2001-06-01

The antimicrobial activities of chloroform, methanol and aqueous extracts of the bark of Gymnanthes lucida, Gliricidia sepium, Lysiloma divaricata, Lysiloma tergemina and Coccolaba cozumelensis were tested against S. lutea, E. coli, S. epidermidis, L. monocytogenes, S. choleraesuis, S. aureus, P. aeruginosa, B. pumillus, S. typhimurium, P. vulgaris, V. cholerae and C. albicans. It was found that methanol extracts of the two Lysiloma species and G. sepium had antimicrobial effects against S. epidermidis, S. aureus, P. aeruginosa, B. pumillus and V. cholerae at doses of 200 microg. The major inhibitory effect was observed with L. tergemina which showed a bacteriostatic effect on S. epidermidis at doses of 400 microg/mL. Copyright 2001 John Wiley & Sons, Ltd.

Reductive dehalogenation of 5-bromouracil by aliphatic organic radicals in aqueous solutions; electron transfer and proton-coupled electron transfer mechanisms

NASA Astrophysics Data System (ADS)

Matasović, Brunislav; Bonifačić, Marija

2011-06-01

Reductive dehalogenation of 5-bromouracil by aliphatic organic radicals CO2-rad , rad CH 2OH, rad CH(CH 3)OH, and rad CH(CH 3)O - have been studied in oxygen free aqueous solutions in the presence of organic additives: formate, methanol or ethanol. For radicals production 60Co γ-radiolysis was employed and the yield of bromide was measured by means of ion chromatography. Both radical anions have reducing potential negative enough to transfer an electron to BrU producing bromide ion and U rad radical. High yields of bromide have been measured increasing proportional to the concentration of the corresponding organic additives at a constant dose rate. This is characteristic for a chain process where regeneration of radical ions occurs by H-atom abstraction by U rad radical from formate or ethanol. Results with the neutral radicals conformed earlier proposition that the reduction reaction of α-hydroxyalkyl radicals proceeds by the proton-coupled electron transfer mechanism ( Matasović and Bonifačić, 2007). Thus, while both rad CH 2OH and rad CH(CH 3)OH did not react with BrU in water/alcohol solutions, addition of bicarbonate and acetate in mmol dm -3 concentrations, pH 7, brought about chain debromination to occur in the case of rad CH(CH 3)OH radical as reactant. Under the same conditions phosphate buffer, a base with higher bulk proton affinity, failed to have any influence. The results are taken as additional proofs for the specific complex formation of α-hydroxyalkyl radicals with suitable bases which enhances radicals' reduction potential in comparison with only water molecules as proton acceptors. Rate constants for the H-atom abstraction from ethanol and formate by U rad radicals have been estimated to amount to about ≥85 and 1200 dm 3 mol -1 s -1, respectively.

Treatment of infectious skin defects or ulcers with electrolyzed strong acid aqueous solution.

PubMed

Sekiya, S; Ohmori, K; Harii, K

1997-01-01

A chronic ulcer with an infection such as methicillin-resistant Staphylococcus aureus is hard to heal. Plastic and reconstructive surgeons often encounter such chronic ulcers that are resistant to surgical or various conservative treatments. We applied conservative treatment using an electrolyzed strong acid aqueous solution and obtained satisfactory results. The lesion was washed with the solution or soaked in a bowl of the solution for approximately 20 min twice a day. Fresh electrolyzed strong acid aqueous solution is unstable and should be stored in a cool, dark site in a sealed bottle. It should be used within a week after it has been produced. Here we report on 15 cases of infectious ulcers that were treated by electrolyzed strong acid aqueous solution. Of these cases, 7 patients were healed, 3 were granulated, and in 5, infection subsided. In most cases the lesion became less reddish and less edematous. Discharge or foul odor from the lesion was decreased. Electrolyzed strong acid aqueous solution was especially effective for treating a chronic refractory ulcer combined with diabetes melitus or peripheral circulatory insufficiency. This clinically applied therapy of electrolyzed strong acid aqueous solution was found to be effective so that this new therapeutic technique for ulcer treatment can now be conveniently utilized.

Spectrally resolved femtosecond photon echo spectroscopy of astaxanthin

NASA Astrophysics Data System (ADS)

Kumar, Ajitesh; Karthick Kumar, S. K.; Gupta, Aditya; Goswami, Debabrata

2010-12-01

We have studied the coherence and population dynamics of Astaxanthin solution in methanol and acetonitrile by spectrally resolving their photon echo signals. Our experiments indicate that methanol has a much stronger interaction with the ultrafast dynamics of Astaxanthin in comparison to that of acetonitrile.

Spectrally resolved femtosecond photon echo spectroscopy of astaxanthin

NASA Astrophysics Data System (ADS)

Kumar, Ajitesh; Karthick Kumar, S. K.; Gupta, Aditya; Goswami, Debabrata

2011-08-01

We have studied the coherence and population dynamics of Astaxanthin solution in methanol and acetonitrile by spectrally resolving their photon echo signals. Our experiments indicate that methanol has a much stronger interaction with the ultrafast dynamics of Astaxanthin in comparison to that of acetonitrile.

Quantitative analysis of fungicide azoxystrobin in agricultural samples with rapid, simple and reliable monoclonal immunoassay.

PubMed

Watanabe, Eiki; Miyake, Shiro

2013-01-15

This work presents analytical performance of a kit-based direct competitive enzyme-linked immunosorbent assay (dc-ELISA) for azoxystrobin detection in agricultural products. The dc-ELISA was sufficiently sensitive for analysis of residue levels close to the maximum residue limits. The dc-ELISA did not show cross-reactivity to other strobilurin analogues. Absorbance decreased with the increase of methanol concentration in sample solution from 2% to 40%, while the standard curve became most linear when the sample solution contained 10% methanol. Agricultural samples were extracted with methanol, and the extracts were diluted with water to 10% methanol adequate. No significant matrix interference was observed. Satisfying recovery was found for all of spiked samples and the results were well agreed with the analysis with liquid chromatography. These results clearly indicate that the kit-based dc-ELISA is suitable for the rapid, simple, quantitative and reliable determination of the fungicide. Copyright © 2012 Elsevier Ltd. All rights reserved.

Preparing polymeric matrix composites using an aqueous slurry technique

NASA Technical Reports Server (NTRS)

Johnston, Norman J. (Inventor); Towell, Timothy W. (Inventor)

1993-01-01

An aqueous process was developed to prepare a consolidated composite laminate from an aqueous slurry. An aqueous poly(amic acid) surfactant solution was prepared by dissolving a poly(amic acid) powder in an aqueous ammonia solution. A polymeric powder was added to this solution to form a slurry. The slurry was deposited on carbon fiber to form a prepreg which was dried and stacked to form a composite laminate. The composite laminate was consolidated using pressure and was heated to form the polymeric matrix. The resulting composite laminate exhibited high fracture toughness and excellent consolidation.

Effects of Shapes of Solute Molecules on Diffusion: A Study of Dependences on Solute Size, Solvent, and Temperature.

PubMed

Chan, T C; Li, H T; Li, K Y

2015-12-24

Diffusivities of basically linear, planar, and spherical solutes at infinite dilution in various solvents are studied to unravel the effects of solute shapes on diffusion. On the basis of the relationship between the reciprocal of diffusivity and the molecular volume of solute molecules with similar shape in a given solvent at constant temperature, the diffusivities of solutes of equal molecular volume but different shapes are evaluated and the effects due to different shapes of two equal-sized solute molecules on diffusion are determined. It is found that the effects are dependent on the size of the solute pairs studied. Evidence of the dependence of the solute-shape effects on solvent properties is also demonstrated and discussed. Here, some new diffusion data of aromatic compounds in methanol at different temperatures are reported. The result for methanol in this study indicates that the effects of solute shape on diffusivity are only weakly dependent on temperature.

Online Monitoring of Methanol Electro-Oxidation Reactions by Ambient Mass Spectrometry

NASA Astrophysics Data System (ADS)

Cheng, Si; Wu, Qiuhua; Dewald, Howard D.; Chen, Hao

2017-06-01

Online detection of methanol electro-oxidation reaction products [e.g., formaldehyde (HCHO)] by mass spectrometry (MS) is challenging, owing to the high salt content and extreme pH of the electrolyte solution as well as the difficulty in ionizing the reaction products. Herein we present an online ambient mass spectrometric approach for analyzing HCHO generated from methanol electro-oxidation, taking the advantage of high salt tolerance of desorption electrospray ionization mass spectrometry (DESI-MS). It was found that HCHO can be detected as PhNHNH+=CH2 ( m/z 121) by DESI after online derivatization with PhNHNH2. With this approach, the analysis of HCHO from methanol electro-oxidation by MS was carried out not only in acidic condition but also in alkaline media for the first time. Efficiencies of different electrodes for methanol oxidation at different pHs were also evaluated. Our results show that Au electrode produces more HCHO than Pt-based electrodes at alkaline pH, while the latter have higher yields at acidic solution. The presented methodology would be of great value for elucidating fuel cell reaction mechanisms and for screening ideal fuel cell electrode materials. [Figure not available: see fulltext.

Insights into water-mediated ion clustering in aqueous CaSO4 solutions: pre-nucleation cluster characteristics studied by ab initio calculations and molecular dynamics simulations.

PubMed

Li, Hui-Ji; Yan, Dan; Cai, Hou-Qin; Yi, Hai-Bo; Min, Xiao-Bo; Xia, Fei-Fei

2017-05-10

The molecular structure of growth units building crystals is a fundamental issue in the crystallization processes from aqueous solutions. In this work, a systematic investigation of pre-nucleation clusters and their hydration characteristics in aqueous CaSO 4 solutions was performed using ab initio calculations and molecular dynamics (MD) simulations. The results of ab initio calculations and MD simulations indicate that the dominant species in aqueous CaSO 4 solutions are monodentate ion-associated structures. Compared with charged ion clusters, neutral clusters are more likely to be present in an aqueous CaSO 4 solution. Neutral (CaSO 4 ) m clusters are probably the growth units involved in the pre-nucleation or crystallization processes. Meanwhile, hydration behavior around ion associated species in aqueous CaSO 4 solutions plays an important role in related phase/polymorphism selections. Upon ion clustering, the residence of some water molecules around Ca 2+ in ion-associated species is weakened while that of some bridging waters is enhanced due to dual interaction by Ca 2+ and SO 4 2- . Some phase/polymorphism selections can be achieved in aqueous CaSO 4 solutions by controlling the hydration around pre-nucleation clusters. Moreover, the association trend between calcium and sulfate is found to be relatively strong, which hints at the low solubility of calcium sulfate in water.

Dispersive liquid-liquid microextraction method based on solidification of floating organic droplet for the determination of thiamphenicol and florfenicol in environmental water samples.

PubMed

Peng, Guilong; He, Qiang; Al-Hamadani, Sulala M Z F; Zhou, Guangming; Liu, Mengzi; Zhu, Hui; Chen, Junhua

2015-05-01

Dispersive liquid-liquid microextraction with solidification of a floating organic droplet (DLLME-SFO) followed by high performance liquid chromatography-ultraviolet (HPLC-UV) detection was applied for the determination of thiamphenicol (TAP), florfenicol (FF) in water samples. 1-Undecanol was used as the extraction solvent which has lower density than water, low toxicity, and low melting point (19°C). A mixture of 800mL acetone (disperser solvent) and 80µL of 1-undecanol (extraction solvent) was injected into 20mL of aqueous solution. After 5min, 0.6g of NaCl was added and the sample vial was shaken. After 5min, the sample was centrifuged at 3500rpm for 3min, and then placed in an ice bath. When the extraction solvent floating on the aqueous solution had solidified, it was transferred into another conical vial where it was melted quickly at room temperature, and was diluted with methanol to 1mL, and analyzed by HPLC-UV detection. Parameters influencing the extraction efficiency were thoroughly examined and optimized. The extraction recoveries (ER) and the enrichment factors (EF) ranged from 67% to 72% and 223 to 241, respectively. The limits of detection (LODs) (S/N=3) were 0.33 and 0.56µgL(-1) for TAP and FF, respectively. Linear dynamic range (LDR) was in the range of 1.0-550µgL(-1) for TAP and 1.5-700µgL(-1) for FF, the relative standard deviations (RSDs) were in the range of 2.6-3.5% and the recoveries of spiked samples ranged from 94% to 106%. Copyright © 2015 Elsevier Inc. All rights reserved.

[Analysis of parameters of serum concentration and pharmacokinetic of liposome and aqueous solution of toatal ginsenoside of ginseng stems and leaves in rats].

PubMed

Zha, Lin; Zhao, Yan; Zhu, Hong-Yan; Cai, En-Bo; Liu, Shuang-Li; Yang, He; Zhao, Ying; Gao, Yu-Gang; Zhang, Lian-Xue

2017-05-01

The experiment was aimed to investigate the difference of plasma concentration and pharmacokinetic parameters between liposome and aqueous solution of toatal ginsenoside of ginseng stems and leaves in rats, such as ginsenosides Rg₁, Re, Rf, Rb₁, Rg₂, Rc, Rb₂, Rb₃, Rd. After intravenous injection of liposome and aqueous solution in rats, the blood was taken from the femoral vein to detect the plasma concentration of the above 9 ginsenoside monomers in different time points by using HPLC. The concentration-time curve was obtained and 3p97 pharmacokinetic software was used to get the pharmacokinetic parameters. After the intravenous injection of ginsenosides to rats, nine ginsenosides were detected in plasma. In general, among these ginsenosides, the peak time of the aqueous solution was between 0.05 to 0.083 3 h, and the serum concentration peak of liposome usually appeared after 0.5 h. After software fitting, the aqueous solution of ginsenoside monomers Rg₁, Re, Rf, Rg₂, Rc, Rd, Rb₃ was two-compartment model, and the liposomes were one-compartment model; aqueous solution and liposome of ginsenoside monomers Rb₁ were three-compartment model; aqueous solution of ginsenoside monomers Rb₂ was three-compartment model, and its liposome was one-compartment model. Area under the drug time curve (AUC) of these 9 kinds of saponin liposomes was larger than that of aqueous solution, and the retention time of the liposomes was longer than that of the aqueous solution; the removal rate was slower than that of the aqueous solution, and the half-life was longer than that of the water solution. The results from the experiment showed that by intravenous administration, the pharmacokinetic parameters of two formulations were significantly different from each other; the liposomes could not only remain the drug for a longer time in vivo, but also reduce the elimination rate and increase the treatment efficacy. As compared with the traditional dosage forms, the total ginsenoside of ginseng stems and leaves can improve the sustained release of the drug, which is of great significance for the research and development of new dosage forms of ginsenosides in the future. Copyright© by the Chinese Pharmaceutical Association.

Utilization of methanol in crude glycerol to assist lipid production in non-sterilized fermentation from Trichosporon oleaginosus.

PubMed

Chen, Jiaxin; Zhang, Xiaolei; Tyagi, Rajeshwar Dayal; Drogui, Patrick

2018-04-01

In this work, methanol in crude glycerol solution was used to assist the lipid production with oleaginous yeast Trichosporon oleaginosus cultivated under non-sterilized conditions. The investigated methanol concentration was 0%, 1.4%, 2.2%, 3.3% and 4.4% (w/v). The results showed that methanol played a significant role in the non-sterilized fermentation for lipid production. The optimal methanol concentration was around 1.4% (w/v) in which the growth of T. oleaginosus was promoted and overcame that of the contaminants. The non-sterilized fed-batch fermentation with initial methanol concentration of 1.4% (w/v) was then performed and high biomass production (43.39 g/L) and lipid production (20.42 g/L) were achieved. Copyright © 2018 Elsevier Ltd. All rights reserved.

Thermodynamic properties of potassium chloride aqueous solutions

NASA Astrophysics Data System (ADS)

Zezin, Denis; Driesner, Thomas

2017-04-01

Potassium chloride is a ubiquitous salt in natural fluids, being the second most abundant dissolved salt in many geological aqueous solutions after sodium chloride. It is a simple solute and strong electrolyte easily dissociating in water, however the thermodynamic properties of KCl aqueous solutions were never correlated with sufficient accuracy for a wide range of physicochemical conditions. In this communication we propose a set of parameters for a Pitzer-type model which allows calculation of all necessary thermodynamic properties of KCl solution, namely excess Gibbs free energy and derived activity coefficient, apparent molar enthalpy, heat capacity and volume, as well as osmotic coefficient and activity of water in solutions. The system KCl-water is one of the best studied aqueous systems containing electrolytes. Although extensive experimental data were collected for thermodynamic properties of these solutions over the years, the accurate volumetric data became available only recently, thus making possible a complete thermodynamic formulation including a pressure dependence of excess Gibbs free energy and derived properties of the KCl-water liquids. Our proposed model is intended for calculation of major thermodynamic properties of KCl aqueous solutions at temperatures ranging from freezing point of a solution to 623 K, pressures ranging from saturated water vapor up to 150 MPa, and concentrations up to the salt saturation. This parameterized model will be further implemented in geochemical software packages and can facilitate the calculation of aqueous equilibrium for reactive transport codes.

Extracting alcohols from aqueous solutions. [USDOE patent application

DOEpatents

Compere, A.L.; Googin, J.M.; Griffith, W.L.

1981-12-02

The objective is to provide an efficient process for extracting alcohols in aqueous solutions into hydrocarbon fuel mixtures, such as gasoline, diesel fuel and fuel oil. This is done by contacting an aqueous fermentation liquor with a hydrocarbon or hydrocarbon mixture containing carbon compounds having 5-18 carbon atoms, which may include gasoline, diesel fuel or fuel oil. The hydrocarbon-aqueous alcohol solution is then mixed with one or more of a group of polyoxyalkylene polymers to extract the alcohol into the hydrocarbon fuel-polyoxyalkylene polymer mixture.

Exploratory studies on some electrochemical cell systems

NASA Astrophysics Data System (ADS)

Chaudhuri, Srikumar; Guha, D.

Exploratory studies were conducted on cell systems with different metal anodes, and iodine and sulphur mixed with graphite powder in a polymer matrix as cathodes, using different electrolytes in non-aqueous and aqueous media as ionic charge carriers. The electrical conductance of the electrolyte solutions in aqueous and non-aqueous solvents, the open circuit voltage (OCV) and short circuit current (SCC) for the different cell systems were measured. To date, the non-aqueous solvents used in our studies were dimethylformamide, formamide, dioxan, and nitrobenzene, and the electrolytes used were potassium iodide, caustic potash, cetyltrimethylammonium bromide (CTAB), sodium lauryl sulphate (SLS) and calcium chloride. These electrolytes were used in both non-aqueous and aqueous media. In general, aqueous electrolyte solutions gave a better performance than non-aqueous electrolyte solutions. Of the aqueous electrolytes, the highest conductance was shown by potassium chloride solution in water (conductance=0.0334 mho). However, the best OCV and SCC were shown by aluminium as anode and iodine as cathode with a saturated solution of caustic potash in water. The OCV was 1.85 V and the SCC was 290 mA cm -2. The highest conductance among the non-aqueous systems was shown by caustic potash in formamide. (Conductance=0.013 mho.) The best OCV and SCC, however, were shown by a zinc anode and iodine cathode with saturated potassium chloride in formamide, having an OCV of 1.55 V and an SCC of 150 mA cm -2. Further studies are in progress to obtain detailed performance data and recharging characteristics of some of the more promising systems reported here.

Optimization of Artificial Propagation in Piracanjuba Fish Brycon orbignyanus Using Cryopreserved Semen.

PubMed

Felizardo, V O; Melo, C C V; Murgas, L D S; Andrade, E S; Navarro, R D; Ftreitas, T F

BACKGROUND: Cryopreserved semen could facilitate procedures during the artificial reproduction in fish. Factors affecting cryopreservation efficiency are important to define efficient protocols. This study investigated the application of cryoprotectants on the quality of piracanjuba fish semen, the sperm concentration required for oocyte fertilization and spermatic activation. We evaluated two intracellular cryoprotectant solutions (DMSO and methanol) and two extracellular cryoprotectant solutions (egg yolk and lactose) to cryopreserved piracanjuba semen. Sperm motility rate, motility duration and spermatic alterations were assessed. The protocol for piracanjuba semen cryopreservation can use solutions including either DMSO or methanol as intracellular cryoprotectant and egg yolk or lactose as extracellular cryoprotectants.

SEPARATION OF PLUTONIUM FROM AQUEOUS SOLUTIONS BY ION-EXCHANGE

DOEpatents

Schubert, J.

1958-06-01

A process is described for the separation of plutonium from an aqueous solution of a plutonium salt, which comprises adding to the solution an acid of the group consisting of sulfuric acid, phosphoric acid, and oxalic acid, and mixtures thereof to provide an acid concentration between 0.0001 and 1 M, contacting the resultant solution with a synthetic organic anion exchange resin, and separating the aqueous phase and the resin which contains the plutonium.

A study on lithium/air secondary batteries-Stability of the NASICON-type lithium ion conducting solid electrolyte in alkaline aqueous solutions

NASA Astrophysics Data System (ADS)

Shimonishi, Yuta; Zhang, Tao; Imanishi, Nobuyuki; Im, Dongmin; Lee, Dong Joon; Hirano, Atsushi; Takeda, Yasuo; Yamamoto, Osamu; Sammes, Nigel

The stability of the high lithium ion conducting glass ceramics, Li 1+ x+ yTi 2- xAl xSi yP 3- yO 12 (LTAP) in alkaline aqueous solutions with and without LiCl has been examined. A significant conductivity decrease of the LTAP plate immersed in 0.057 M LiOH aqueous solution at 50 °C for 3 weeks was observed. However, no conductivity change of the LTAP plate immersed in LiCl saturated LiOH aqueous solutions at 50 °C for 3 weeks was observed. The pH value of the LiCl-LiOH-H 2O solution with saturated LiCl was in a range of 7-9. The molarity of LiOH and LiCl in the LiOH and LiCl saturated aqueous solution were estimated to be 5.12 and 11.57 M, respectively, by analysis of Li + and OH -. The high concentration of LiOH and the low pH value of 8.14 in this solution suggested that the dissociation of LiOH into Li + and OH - is too low in the solution with a high concentration of Li +. These results suggest that the water stable LTAP could be used as a protect layer of the lithium metal anode in the lithium/air cell with LiCl saturated aqueous solution as the electrolyte, because the content of OH - ions in the LiCl saturated aqueous solution does not increase via the cell reaction of Li + 1/2O 2 + H 2O → 2LiOH, and LTAP is stable under a deep discharge state.

[Determination of estrogen residues in drinking water by on-line solid phase extraction based on sol-gel technique coupled with high performance liquid chromatography].

PubMed

Li, Longfei; Su, Min; Shi, Xiaolei; Wang, Yana; Wang, Minmin; He, Jinxing

2014-02-01

A method for the determination of diethylstilbestrol (DES), hexestrol (HEX) and dienestrol (DS) residues in drinking water was established by on-line solid phase extraction (SPE) coupled with high performance liquid chromatography (HPLC). The material synthesized on the base of sol-gel technology was employed as adsorbent. This material was prepared using 3-aminopropyltriethoxysilane (APTES) as the functional monomer, tetraethoxysilane (TEOS) as the crosslinking agent, and acetic acid as the initiator. The synthesized adsorbent showed outstanding property for the estrogen extraction. The estrogen can be caught effectively from water samples and the extraction can be achieved rapidly. Some important parameters, such as pH of sample solution, eluent solvents, loading flow rate, which might influence extraction efficiency, were optimized. The results indicated that the limit of detection (S/N = 3) of the developed method could reach 0.07-0.13 microg/L under the conditions of pH 7.0 of sample solution, methanol and 1% (v/v) acetic acid aqueous solution as the eluent solvent and the loading flow rate of 2 mL/min. The recoveries of the three estrogens from the water samples at three spiked levels ranged from 82.31% to 99.43% with RSD of 1.61%-7.15%. The method was simple, rapid, and suitable to detect the trace residues of estrogens in drinking water.

Quantitative HPLC Analysis of a Psychotherapeutic Medication: Simultaneous Determination of Amitriptyline Hydrochloride and Perphenazine

NASA Astrophysics Data System (ADS)

Ferguson, Glenda K.

1998-12-01

A quantitative high-performance liquid chromatography (HPLC) laboratory experiment which entails the isocratic separation and simultaneous determination of the two active components of a commercial antipsychotic tablet has been developed. The prescription formulation used in this experiment contains amitriptyline hydrochloride (a tricyclic antidepressant) and perphenazine (a tranquilizer). Our experiment makes use of a straightforward HPLC separation on a cyanopropyl-packed column with an acetonitrile:methanol:aqueous monopotassium phosphate mobile phase pumped at a flow rate of 2.0 mL/min. Analytes are detected by UV absorbance at 215 nm. These conditions yield highly symmetrical and well-resolved peaks in less than 5 min after the injection of a mixture. In the experiment, students are given amitriptyline hydrochloride-perphenazine tablets without the manufacturer's labeled composition claim and a stock solution mixture with known concentrations of amitriptyline hydrochloride and perphenazine. They prepare four standards and a pharmaceutical sample of unknown concentration, assay each solution in quadruplicate, and plot average peak areas of the concentrations of the known solutions in the construction of a standard curve. From the mathematical relationships that result, the average masses of amitriptyline hydrochloride and perphenazine in the prescription tablet are determined. Finally, the standard deviations of the mean masses are calculated. The entire laboratory procedure and statistical data analysis can be completed in a single 3-hour period.