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PubMed2005

Interpretation of the ultrasonic effect on induction time during BaSO4 homogeneous nucleation by a cluster coagulation model.

The effects of power ultrasound on the induction time of BaSO4 are studied experimentally and theoretically. In the experiments, barium sulfate is precipitated by mixing aqueous BaCl2 solution and Na2SO4 solution. The induction time is identified and measured by recording the change of turbidity in solution. Various energy inputs are used to investigate the effect of energy on nucleation. The results show that the induction time decreases with increasing supersaturation and increasing energy input. Employing the classical nucleation theory, the interfacial tension is estimated. In addition, the ultrasonic effects on nucleation order (n) and the nucleation coefficient (kN) are also investigated. A cluster coagulation model, which brings together the current nucleation models and the theories describing the behavior of colloidal suspensions, was applied to estimate the induction time under various energy inputs. A comparison between the results of model and the results of experiments shows that the number of monomers in dominating clusters (g) in the solution remains constant with increasing of energy input.

Journal Article↗
PubMed2005

Effects of three purgative decoctions on inflammatory mediators.

In traditional Chinese medicine (TCM), there are three Cheng-Chi-Tang decoctions (CCTDs) including: Ta-Cheng-Chi-Tang (TCCT), Xiao-Chen-Chi-Tang (XCCT) and Tiao-Wei-Chen-Chi-Tang (TWCCT), which are the frequently used purgative remedies to treat "internal heat"-induced symptoms like a bloated and painful abdomen, hard stools and fever, etc. Constituents in each formulation are Rheum palmatum L. (Polygonaceae), Magnolia officinalis Rehd. et Wils. (Magnoliaceae), Citrus aurantium L. (Rutaceae), Mirabilitum (mirabilite, crystals of sodium sulfate, Na2SO4) for TCCT; Rheum palmatum, Magnolia officinalis, Citrus aurantium for XCCT; and Rheum palmatum, Mirabilitum, Glycyrrhiza uralensis Fisch. (Leguminosae) for TWCCT. However, the underlying mechanisms for purging internal pathological heat are far from fully clarified, and few scientific investigations have been carried out to delineate the relationships between the anti-inflammatory effects and laxative potencies of these formulations. In this study, the anti-inflammatory effects of the three CCTDs on lipopolysaccharide (LPS)-induced nitric oxide (NO) and prostaglandin E (PGE2) production in RAW 264.7 cells, carrageenan-induced paw edema in mice and the laxative effect in mice were explored. The results showed that TCCT inhibited LPS-induced NO and PGE2 production and inducible nitric oxide synthase (iNOS) expression in RAW 264.7 cells more effectively than did XCCT or TWCCT. Moreover, paw edema of carrageenan-treated mice was significantly attenuated in mice pretreated with 1 g/kg TCCT. TCCT also showed the strongest purgative activity among the three formulations. These findings indicate that TCCT has anti-inflammatory effects in addition to its traditionally known purgative activities. It may have potential to treat inflammatory disease conditions.

Animals↗
PubMed2005

Methods to improve electrochemical treatment effect of dye wastewater.

Several methods, including changing electrolyte concentration, temperature, stirring, and voltage were studied to improve the degradation effect of electrochemical treatment in dye wastewater. In addition, nanophase TiO2 catalyst and Co-Bi-PbO2/Ti anode have been prepared to expedite color removal. Enhancement of temperature leads to proportional increase of color removal. As for voltage, at low levels its increase could greatly improves color removal. After voltage reaches about 3.0 V, its improvement effect declines quickly. The influence of electrolyte concentration and aerating on color removal are similar to that of voltage. So it favored to degrade organic pollutants using high salt concentration, high voltages and large electric current to improve treatment effect. However, the efficiency of energy supplied during electrolysis decreases. A nonlinear model is established to evaluate the influence of electrolyte concentration and voltage on color removal. The model agrees with the experiment data very well. It is suggested by the simulation result of this model that electrolysis degradation should better be carried out at about 3.0 V, in 0.01 M Na2SO4 concentration for high energy efficiency. Additionally, either catalyst or Co-Bi-PbO2/Ti anode brings about 0.15 times more color removal without increasing electric current. Together, they could bring forth some 0.22 times higher color removal.

Azo Compounds↗
PubMed2006

Microwave remediation of soil contaminated with hexachlorobenzene.

This study describes the remediation of hexachlorobenzene (HCB) contaminated soils by microwave (MW) radiation in a sealed vial. When powdered MnO2 was used as MW absorber, a complete removal of HCB was obtained with 10 min MW by the addition of H2SO4 (50%). But no significant decomposition was observed by the addition of NaOH (10 mol/L) or H2O in the same conditions. In contrast, when powdered Fe was used instead of MnO2, the difference of HCB removals between H2SO4 and NaOH were not obvious. It is noteworthy that more than 95% removal was achieved in any case when the sole aqueous solution of H2SO4, NaOH, H2O or Na2SO4 was added without MnO2 or Fe. As a result, it is possible that water itself contained in the damp soil may act as MW absorber and remediate the contaminated soil without addition of any other MW absorbers. Gas chromatograph/mass spectrum (GC/MS) analysis detected no intermediates in all the processes. The decomposition mechanism of HCB by MW radiation was suggested as the binding of HCB and soil. Whatever fragments formed from HCB by heat were tightly bound to the soil, making it impossible to extract them out. In the end, treatment of practical HCB contaminated soil by MW reduced HCB from 55.8 mg/kg to 0.91 mg/kg.

Environmental Restoration and Remediation↗
PubMed2006

Electrochemical treatment of textile dyes and dyehouse effluents.

The electrochemical oxidation of textile effluents over a titanium-tantalum-platinum-iridium anode was investigated. Batch experiments were conducted in a flow-through electrolytic cell with internal recirculation at current intensities of 5, 10, 14 and 20A, NaCl concentrations of 0.5, 1, 2 and 4% and recirculation rates of 0.81 and 0.65 L/s using a highly colored, synthetic effluent containing 16 textile dyes at a total concentration of 361 mg/L and chemical oxygen demand (COD) of 281 mg/L. Moreover, an actual dyehouse effluent containing residual dyes as well as various inorganic and organic compounds with a COD of 404 mg/L was tested. In most cases, quantitative effluent decolorization was achieved after 10-15 min of treatment and this required low energy consumption; conversely, the extent of mineralization varied between 30 and 90% after 180 min depending on the operating conditions and the type of effluent. In general, treatment performance improved with increasing current intensity and salinity and decreasing solution pH. However, the use of electrolytes not containing chloride (e.g. FeSO4 or Na2SO4) suppressed degradation. Although the acute toxicity of the actual effluent to marine bacteria Vibrio fischeri was weak, it increased sharply following treatment, thus suggesting the formation of persistent toxic by-products.

Aliivibrio fischeri↗
PubMed2006

Photoelectrocatalytic oxidation of remazol turquoise blue and toxicological assessment of its oxidation products.

The ability of photoelectrocatalytic oxidation to degrade the commercially important copper-phtalocyanine dye, remazol turquoise blue 15 (RTB) was investigated. The best experimental condition was optimized, evaluating the performance of Ti/TiO2 thin-film electrodes prepared by sol-gel method in the decolourization of 32 mg L(-1) RTB dye in 0.5 mol L(-1) Na2SO4 pH 8 and applied potential of +1.5 V versus SCE under UV irradiation. Spectrophotometric measurements, high performance liquid chromatography, dissolved organic carbon (TOC) evaluation and stripping analysis of yielding solution obtained after 3 h of photoelectrolysis leads to 100% of absorbance removal from wavelength of 250-800 nm, 79.6% of TOC reduction and the releasing of up to 54.6% dye-bound copper (0.85 mg L(-1)) into the solution. Both, original and oxidized dye solution did not presented mutagenic activity with the strains TA98 and TA100 of Salmonella in the presence and absence of S9 mix at the tested doses. Nevertheless, the yielding photoelectrocatalytic oxidized solution showed an increase in the acute toxicity for Vibrio fischeri bacteria, explained by copper liberation during treatment.

Catalysis↗
PubMed2004

Equilibrium hydrogen exchange reveals extensive hydrogen bonded secondary structure in the on-pathway intermediate of Im7.

The four-helical immunity protein Im7 folds through an on-pathway intermediate that has a specific, but partially misfolded, hydrophobic core. In order to gain further insight into the structure of this species, we have identified the backbone hydrogen bonds formed in the ensemble by measuring the amide exchange rates (under EX2 conditions) of the wild-type protein and a variant, I72V. In this mutant the intermediate is significantly destabilised relative to the unfolded state (deltadeltaG(ui) = 4.4 kJ/mol) but the native state is only slightly destabilised (deltadeltaG(nu) = 1.8 kJ/mol) at 10 degrees C in 2H2O, pH* 7.0 containing 0.4 M Na2SO4, consistent with the view that this residue forms significant non-native stabilising interactions in the intermediate state. Comparison of the hydrogen exchange rates of the two proteins, therefore, enables the state from which hydrogen exchange occurs to be identified. The data show that amides in helices I, II and IV in both proteins exchange slowly with a free energy similar to that associated with global unfolding, suggesting that these helices form highly protected hydrogen-bonded helical structure in the intermediate. By contrast, amides in helix III exchange rapidly in both proteins. Importantly, the rate of exchange of amides in helix III are slowed substantially in the Im7* variant, I72V, compared with the wild-type protein, whilst other amides exchange more rapidly in the mutant protein, in accord with the kinetics of folding/unfolding measured using chevron analysis. These data demonstrate, therefore, that local fluctuations do not dominate the exchange mechanism and confirm that helix III does not form stable secondary structure in the intermediate. By combining these results with previously obtained Phi-values, we show that the on-pathway folding intermediate of Im7 contains extensive, stable hydrogen-bonded structure in helices I, II and IV, and that this structure is stabilised by both native and non-native interactions involving amino acid side-chains in these helices.

Bacterial Proteins↗
PubMed2004

Enhancing sensitivity or resolution of homonuclear correlation experiment for half-integer quadrupolar nuclei.

We have recently introduced double-quantum homonuclear correlation NMR experiment for half-integer quadrupolar nuclei in solids, which was based on rotary resonance recoupling [J. Chem. Phys. 120 (2004) 2835]. In this contribution we show on two 23Na (I=3/2) containing samples, Na2SO4 and Na2HPO4, that the efficiency of the experiment can be substantially enhanced by adding rotor assisted population transfer (RAPT) and Carr-Purcell-Meiboom-Gill (CPMG) sequences to it. We also present an upgraded two-dimensional experiment, in which double- and six-quantum coherences are correlated during t1 evolution period, yielding a high-resolution isotropic spectrum along an indirectly detected dimension. The sensitivity of the upgraded experiment is, however, greatly reduced compared to the sensitivity of the original experiment, so that its application is feasible only when RAPT and CPMG can be used as well.

Journal Article↗
PubMed2026

Long-term saline-alkaline selection rewires the growth-survival trade-off in Priestia megaterium.

Saline-alkaline soils impose persistent osmotic, ionic, pH, and nutrient stress on soil microorganisms, but the evolutionary routes by which beneficial bacteria adapt to such conditions remain poorly resolved. We performed adaptive laboratory evolution to examine the adaption of the plant growth-promoting rhizobacterium Priestia megaterium HA22 to long-term oligotrophic saline-alkaline selection. After 175 serial transfers, the evolved lineage proliferated stably at 40 g L-1 Na2SO4 at pH 10.0, whereas the wild-type strain failed to proliferate. Genome resequencing and allelic replacement revealed a 5-bp insertion in spo0A, the master sporulation regulator, as a major adaptive mutation. This mutation abolished sporulation; shortened the lag phase; and enhanced vegetative growth, nutrient uptake, and expression of tricarboxylic acid cycle and nitrogen metabolism gene under saline-alkaline stress. According to untargeted metabolomics, adaptation was accompanied by increased amino acid metabolism and aminoacyl-tRNA biosynthesis, with proline, isoleucine and pantothenic acid functionally promoting growth. A point mutation in ugpB enhanced glycerol-3-phosphate uptake, increased peptidoglycan and wall teichoic acid levels, and partially rescued the survival cost of the spo0A mutation. In greenhouse assays under combined saline-alkaline stress, the evolved strain increased soybean shoot dry weight and root dry weight by 56.08% and 27.02%, respectively. These results indicate that prolonged, predictable saline-alkaline selection can favor active growth rather than dormancy when compensatory cell envelope reinforcement buffers survival costs.

Adaptive laboratory evolution↗
PubMed2006

Effect of sulfur compounds on biological reduction of nitric oxide in aqueous Fe(II)EDTA2- solutions.

Biological reduction of nitric oxide (NO) in aqueous solutions of EDTA chelated Fe(II) is one of the main steps in the BioDeNOx process, a novel bioprocess for the removal of nitrogen oxides (NOx) from polluted gas streams. Since NOx contaminated gases usually also contain sulfurous pollutants, the possible interferences of these sulfur compounds with the BioDeNOx process need to be identified. Therefore, the effect of the sulfur compounds Na2SO4, Na2SO3, and H2S on the biological NO reduction in aqueous solutions of Fe(II)EDTA2- (25 mM, pH 7.2, 55 degrees C) was studied in batch experiments. Sulfate and sulfite were found to not affect the reduction rate of Fe(II)EDTA2- complexed NO under the conditions tested. Sulfide, either dosed externally or formed during the batch incubation out of endogenous sulfur sources or the supplied sulfate or sulfite, influences the production and consumption of the intermediate nitrous oxide (N2O) during Fe(II)EDTA2- bound NO reduction. At low concentrations (0.2 g VSS/l) of denitrifying sludge, 0.2 mM free sulfide completely inhibited the nitrosyl-complex reduction. At higher biomass concentrations (1.3-2.3 g VSS/l), sulfide (from 15 microM to 0.8 mM) induced an incomplete NO denitrification with N2O accumulation. The reduction rates of NO to N2O were enhanced by anaerobic sludge, presumably because it kept FeEDTA in the reduced state.

Bacteria, Anaerobic↗
PubMed1992

Helicobacter pylori lipopolysaccharide effect on the synthesis and secretion of gastric sulfomucin.

The effect of H. pylori lipopolysaccharide on the synthesis and secretion of sulfated mucin in gastric mucosa was investigated using mucosal segments incubated in the presence of [3H]proline, [3H]glucosamine and [35S]Na2SO4. The lipopolysaccharide, while showing no discernible effect on the apomucin synthesis was found to inhibit the process of mucin glycosylation and sulfation, which at 100 micrograms/ml lipopolysaccharide reached the optimal inhibition of 65%. The analysis of mucin secretory responses revealed that the lipopolysaccharide by first 15 min caused a 57% stimulation in sulfomucin secretion followed thereafter by inhibition, which reached maximum of 32% by 45 min. The results suggest that colonization of gastric mucosa by H. pylori may be detrimental to the process of gastric sulfomucin synthesis and secretion.

Animals↗
PubMed1995

Photocycle of halorhodopsin from Halobacterium salinarium.

The light-driven chloride pump, halorhodopsin, is a mixture containing all-trans and 13-cis retinal chromophores under both light and dark-adapted conditions and can exist in chloride-free and chloride-binding forms. To describe the photochemical cycle of the all-trans, chloride-binding state that is associated with the transport, and thereby initiate study of the chloride translocation mechanism, one must first dissect the contributions of these species to the measured spectral changes. We resolved the multiple photochemical reactions by determining flash-induced difference spectra and photocycle kinetics in halorhodopsin-containing membranes prepared from Halobacterium salinarium, with light- and dark-adapted samples at various chloride concentrations. The high expression of cloned halorhodopsin made it possible to do these measurements with unfractionated cell envelope membranes in which the chromophore is photostable not only in the presence of NaCl but also in the Na2SO4 solution used for reference. Careful examination of the flash-induced changes at selected wavelengths allowed separating the spectral changes into components and assigning them to the individual photocycles. According to the results, a substantial revision of the photocycle model for H. salinarium halorhodopsin, and its dependence on chloride, is required. The cycle of the all-trans chloride-binding form is described by the scheme, HR-hv-->K<==>L1<==>L2<==>N-->HR, where HR, K, L, and N designate halorhodopsin and its photointermediates. Unlike the earlier models, this is very similar to the photoreaction of bacteriorhodopsin when deprotonation of the Schiff base is prevented (e.g., at low pH or in the D85N mutant). Also unlike in the earlier models, no step in this photocycle was noticeably affected when the chloride concentration was varied between 20 mM and 2 M in an attempt to identify a chloride-binding reaction.

Bacteriorhodopsins↗
PubMed1997

Temperature and amiloride alter taste nerve responses to Na+, K+, and NH+4 salts in rats.

The effects of adaptation/stimulus temperature (25 degrees C vs. 35 degrees C) on taste nerve responses to salt stimulation and amiloride suppression were assessed in rats. We measured the integrated responses of the chorda tympani nerve to 500 mM concentrations of NaCl, Na2SO4, sodium acetate (NaAc), KCl, K2SO4, potassium acetate (KAc), NH4Cl, (NH4)2SO4, and ammonium acetate (NH4Ac) mixed with or without 100 microM amiloride hydrochloride at 35 degrees C. Taste nerve responses to all Na+ and NH4+ salts, but not K/ salts, were significantly smaller at 25 degrees C than at 35 degrees C. Amiloride significantly suppressed taste nerve responses to all salts (Na+ salts > K+ salts > NH4+ salts); amiloride suppression of Na+ and NH4+ salts was significantly greater at 25 degrees C than at 35 degrees C. Benzamil-HCl, a more potent Na+ channel blocker compared to amiloride, strongly suppressed taste nerve responses to NaCl and KCl, but not to NH4Cl. Amiloride and benzamil suppression of NaCl responses were similar; however, amiloride suppressed KCl responses more than did benzamil. The results suggest that: (1) amiloride-sensitive Na+ channels are involved to varying degrees in the transduction of sodium and potassium salt taste, and (2) amiloride may inhibit membrane proteins other than passive Na+ channels during stimulation with potassium and ammonium salts.

Acetates↗
PubMed2000

Study on TEMPO-mediated selective oxidation of hyaluronan and the effects of salt on the reaction kinetics.

2,2,6,6-Tetramethyl-1-piperidinyloxy radical (TEMPO)-mediated oxidation of hyaluronan was studied at pH 10.2 and temperature of 0 degrees C with NaOCl as the primary oxidant. As with other polysaccharides, a high selectivity of oxidation was observed. The degradation of the polymer was essentially caused by the oxidation process. The primary oxidant and the pH of the reaction mixture did not alter the molecular weight of hyaluronan during oxidation. The kinetics of the oxidation process was investigated at different concentrations of reactants and the inorganic salts, NaBr, NaCl, and Na2SO4. An increase in the salt concentration in the mixture causes a major decrease in the rate of the oxidation, and this decrease is independent of the nature of the salt.

Catalysis↗
PubMed1978

Use of a sulfate: hydrogen sulfate buffer to preserve urine for steroid analysis.

1. HCI, commonly used to preserve urine for steroid analysis, cannot safely be supplied to out of town patients. 2. An equimolar mixture of Na2SO4 and NaHSO4 is a safe alternative which may be used to protect specimens en route to the laboratory. 3. Addition of bisulfate buffer to urine (20 g/l) reduced the pH to 2.0-3.5 (31 specimens; 24 hr urine volumes, 560-3320 ml). 4. Little change in pH was observed when buffered urine (12 specimens) was kept at 30 degrees for 14 days (initial pH 2.62 +/- 0.38 (mean +/- standard deviation); PH after 14 days, 2.59 +/- 0.48). 5. Analysis of the creatinine, 17-oxosteroids, 17-oxogenicsteroids, estrogens, pregnanediol, androsterone + etiocholanolone and estriol in urine samples acidified to pH 2-3 with HCl, and in the same samples acidified with buffer, gave results which were indistinguishable from each other. 6. Almost no change in steroid and creatinine concentrations was observed in samples of buffered urine kept for 10 days at room temperature (20-26 degrees).

Buffers↗
PubMed1997

Purification, biochemical properties and substrate specificity of a catechol 1,2-dioxygenase from a phenol degrading Acinetobacter radioresistens.

A catechol 1,2-dioxygenase (C1,2O) has been purified to homogeneity from Acinetobacter radioresistens grown on phenol as the sole carbon and energy source. The C1,2O appears to be a homodimer, with a molecular mass of 78,000 Da. At relatively high ionic strengths (0.5 M Na2SO4) subunit dissociation occurs and the monomeric unit (38,700 Da) is shown to be active. This phenomenon has never been observed before in dioxygenases. The purified C1,2O contains 0.96 iron(III) ions per unit and spectroscopic measurements suggest the presence of one high-spin iron(III) ion in an environment characteristic of intradiol cleaving enzymes. The NH2-terminal amino acid sequence has been determined and compared to the primary structures of intradiol rings cleaving dioxygenases from other Acinetobacter strains revealing 45% homology with the benzoate-grown A. calcoaceticus ADP-1 and an identity of only one of the 20 amino acids sequenced for the phenol-grown A. calcoaceticus NCIB 8250.

Acinetobacter↗
PubMed1984

Determination of some tricyclic neuroleptics by reversed-phase high-performance liquid chromatography with ultraviolet and polarographic detection.

The liquid chromatographic behaviour of various neuroleptics from the classes of tricyclic dibenzothiepins, -oxepins, -selenepins and similar substances was studied in an ion-pair reversed-phase system using a C4180 chemically bonded stationary phase and a methanol-water-acetic acid mobile phase. The best separation was attained with 70% methanol, 1.8% acetic acid and water, containing 0.005 M sodium pentanesulphonate, 1.2 X 10(-4) M EDTA and 0.5 g/l Na2SO4. For the detection, an ultraviolet spectrophotometric and a polarographic detector were connected in series. The detection was carried out at 254 nm and at a potential of a dropping mercury electrode of -1.0 V (vs. Ag/AgCl). The UV detector is universal, while the polarographic detector does not respond to compounds simultaneously containing two heteroatoms (O, S) in the central seven-membered ring. The detection limits are of the order of one to tens of nanograms, the polarographic detector being somewhat more sensitive for most of the compounds; the error of the determination is a few per cent. The method was applied to the determination of isofloxythepin and oxyprothepin in pharmaceutical preparations.

Antidepressive Agents, Tricyclic↗
PubMed2003

Aprotinin conformational distributions during reversed-phase liquid chromatography. Analysis by hydrogen-exchange mass spectrometry.

Hydrogen-exchange mass spectrometry analysis of the stable protein aprotinin during reversed-phase liquid chromatography shows both native and unfolded protein. The behavior is consistent with only two conformational states, a near-native state and a fully solvent-accessible state, with reversible interchange of species within and between the mobile and stationary phases. The amount of unfolded form is greater on C18 relative to C4 alkyl modified silica surfaces. The addition of (NH4)2SO4, Na2SO4, NaCl, or NaSCN to the mobile phase stabilized native conformation on the chromatographic surface, especially on the C4 media. Finally, the retention and the proportion of denatured form increases with added salts in anorder consistent with the lyotropic series, but reversed from that observed for small molecules.

Aprotinin↗