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Alkaline Conditions (alkaline + condition)
Selected AbstractsSearch of Microorganisms that Degrade PAHs under Alkaline ConditionsENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 4 2004A. Gerbeth Abstract Bacterial strains were enriched from building rubble contaminated with polycyclic aromatic hydrocarbons (PAHs). These strains were studied as an inoculum in bioremediation processes with contaminated building rubble. The selection criteria for the bacteria were broad profiles in PAH degradation, stable expression of the traits and tolerance to alkaline conditions. Various strains of Micrococcus sp., Dietzia sp., Rhodococcus sp. and Pseudomonas sp. met the selection criteria. In general, degradative activity was limited at higher pH values. Strains of Micrococcus were suitable for practical use as complete degradation of various PAHs was observed at pH values exceeding 10. Strains of Dietzia sp. showed broad PAH degradation profile, but in some cases degradation came to a halt leaving some of the PAHs unutilized. With Dietzia sp. this could be due to inhibitory effects from the accumulation of toxic PAH metabolic products and/or growth-limiting media conditions. [source] Synthesis of New Resorcinarenes Under Alkaline ConditionsHELVETICA CHIMICA ACTA, Issue 10 2005Jean-Marc Bourgeois The preparation of functionalized resorcinarenes is described. Thus, 2-nitroresorcinol (=,2-nitrobenzene-1,2-diol), 2-acetylresorcinol (=,1-(2,6-dihydroxyphenyl)ethanone), and 2,6-dihydroxybenzoic acid were treated with formaldehyde in alkaline medium to give the corresponding resorcinarenes 1,3 (Scheme,1). This method is also applicable for resorcinol (=,benzene-1,3-diol) itself, but the yields are poorer. In this case, the molecule formed is the simplest resorcinarene 4 on which a number of substituents can be inserted between the two OH groups. Thus, bromation of 4 yields 5 (Scheme,2). Some properties and conformations of these new products are discussed, and the X-ray crystal structures of the nitro and bromo compounds 1 and 5, respectively, are presented. [source] Expeditious Syntheses of Conjugated Allenyl Esters and Oxazoles Through a Cascade Reaction of ,-Alkynyl Malonates under Alkaline Conditions.CHEMINFORM, Issue 28 2006Shigeki Sano Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Systemic and local effects of long-term exposure to alkaline drinking water in ratsINTERNATIONAL JOURNAL OF EXPERIMENTAL PATHOLOGY, Issue 4 2001Marina E.T. Merne Alkaline conditions in the oral cavity may be caused by a variety of stimuli, including tobacco products, antacids, alkaline drinking water or bicarbonate toothpaste. The effects of alkaline pH on oral mucosa have not been systematically studied. To assess the systemic (organ) and local (oral mucosal) effects of alkalinity, drinking water supplemented with Ca(OH)2 or NaOH, with pH 11.2 or 12 was administered to rats (n = 36) for 52 weeks. Tissues were subjected to histopathological examination; oral mucosal biopsy samples were also subjected to immunohistochemical (IHC) analyses for pankeratin, CK19, CK5, CK4, PCNA, ICAM-1, CD44, CD68, S-100, HSP 60, HSP70, and HSP90. At completion of the study, animals in the study groups had lower body weights (up to 29% less) than controls despite equal food and water intake, suggesting a systemic response to the alkaline treatment. The lowest body weight was found in rats exposed to water with the highest pH value and starting the experiment when young (6 weeks). No histological changes attributable to alkaline exposure occurred in the oral mucosa or other tissues studied. Alkaline exposure did not affect cell proliferation in the oral epithelium, as shown by the equal expression of PCNA in groups. The up-regulation of HSP70 protein expression in the oral mucosa of rats exposed to alkaline water, especially Ca(OH)2 treated rats, may indicate a protective response. Intercellular adhesion molecule-1 (ICAM-1) positivity was lost in 6/12 rats treated with Ca(OH)2 with pH 11.2, and loss of CD44 expression was seen in 3/6 rats in both study groups exposed to alkaline water with pH 12. The results suggest that the oral mucosa in rats is resistant to the effects of highly alkaline drinking water. However, high alkalinity may have some unknown systemic effects leading to growth retardation, the cause of which remains to be determined. [source] Preparation of shuttle-like Sb2S3 nanorod-bundles via a solvothermal approach under alkaline conditionCRYSTAL RESEARCH AND TECHNOLOGY, Issue 2 2010Ling Zhang Abstract Uniform shuttle-like Sb2S3 nanorod-bundles were synthesized via a polyvinylpyrrolidone (PVP) assisted solvothermal approach under alkaline condition, using antimony chloride (SbCl3) and thiourea (CH4N2S, Tu) as the starting materials in ethanol. The phase structure, composition and morphology of the product were characterized by means of X-ray diffraction (XRD), energy dispersive X-ray spectrometry (EDS), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM). XRD and EDS results confirm that the synthesized Sb2S3 nanorod-bundles have an orthorhombic structure and an atomic ratio of 3:2 for S:Sb. TEM and HRTEM results show that the shuttle-like Sb2S3 bundles are composed of nanorods with a size distribution of 20-40 nm and growing along c-axis. Furthermore, experiments under different reaction conditions were carried out and the mechanism for the growth of nanorod-bundles was discussed (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Physiological Responses of Krishum (Iris lactea Pall. var. chinensis Koidz) to Neutral and Alkaline SaltsJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 6 2008Y. Wang Abstract The aims of this study were to compare the physiological responses of krishum (Iris lactea Pall. var. chinensis Koidz) to neutral and alkaline salt stress and identify and examine the mechanisms involved in plant response to salt treatments. In this study, biomass, ion accumulation (Na+, K+, Ca2+, Mg2+), organic solute (proline) concentration, rate of membrane electrolyte leakage (REL) and antioxidase activities including those of superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6) and peroxidase (POD, EC 1.11.1.7) were investigated in krishum under different concentrations of NaCl, Na2CO3 and the mixture of the two salts in the same volume. All three treatments caused increases in Na+ concentration, proline content and REL and decreases in root Mg2+ and K+ content. Increased Ca2+ and antioxidase activities were observed at lower external Na+ concentrations. However, at higher external Na+ levels, decreased Ca2+ and antioxidase activities were detected. Alkaline salt resulted in more damage to krishum than neutral salt including lower SOD, POD and CAT activities and decreased proline content, relative to neutral salt. High Na+ and low K+ in krishum intensified ion toxicity under alkaline condition. Alkaline salt caused greater harm to plants than neutral salt, the primary reason of which might be the lower Ca2+ content in the plant under alkaline salt stress. [source] Antibacterial activity of cationically modified cotton fabric with carboxymethyl chitosanJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2008Amira M. El-Shafei Abstract A water-soluble carboxymethyl chitosan was prepared with a view to develop a multifunctional finish on cotton. Carboxymethyl chitosan (CMCTS) was synthesized by chemical reaction of chitosan with monochloroacetic acid under alkaline condition. The water soluble CMCTS was applied to cationized cotton with different concentrations. The treated fabrics were characterized through monitoring the textile physical properties and for the antibacterial activity against Escherichia coli DSMZ 498 and Micrococcus luteus ATCC 9341. The results obtained show that the physical properties of the treated fabrics are improved by increasing the CMCTS concentration, as well as the antibacterial activity. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] ACTIVITY DISTRIBUTION OF DIGESTIVE PROTEASES FROM NEMIPTERUS VIRGATUS AND THEIR RESPONSES TO pH VALUE AND TEMPERATUREJOURNAL OF FOOD PROCESS ENGINEERING, Issue 1 2008HONG TAO ABSTRACT In the present study, three groups (I,III) of Nemipterus virgatus, with average body weights of 154.36, 250.72 and 329.09 g, respectively, were used to investigate the changes in the activity and distribution of digestive proteases in different organs and sections of the digestive tract. Another group of N. virgatus (average body weight of 188.41 g) was used to analyze the changes in the activity of digestive proteases in response to various pH values and temperatures. The activity of digestive proteases in all analyzed organs increased with the increase of body weight at the range of 154.36,329.09 g. The activities of digestive proteases in the different sections of the digestive tract were compared, and a similar change was found among groups I,III. The activities of digestive proteases from various organs were in a descending order: pylorus ceca > stomach > foregut > midgut > hindgut > hepatopancreas. Through observing the zymograms of substrate,sodium dodecil sulphate-polyacrylamide gel electrophoresis, many kinds of digestive proteases could be found in different organs and the varieties were changed with the change of body weight. Two peaks in the diagram between protease activity and pH value were found at pH 3.0 and 10.0, respectively. The activity under alkaline condition was 60% higher than that under acidic condition. The optimal temperature for protease activity was 50C, while the protease activity at 10C was only 30% of that at 50C. PRACTICAL APPLICATIONS Nemipterus virgatus is one of the most important commercial fishes in the East China Sea and South China Sea. The digestive tract of N. virgatus is rich in digestive proteases and they can be employed as important biotechnological tools. The activities of digestive proteases from various organs and the effects of pH value and temperature on them were investigated in this study. The effect of body weight of N. virgatus was also evaluated. All these information would be helpful to extensively utilize this resource for the fish process industry. [source] Purification and molecular characterization of subtilisin-like alkaline protease BPP-A from Bacillus pumilus strain MS-1LETTERS IN APPLIED MICROBIOLOGY, Issue 3 2006T. Miyaji Abstract Aims:, The present study was conducted by screening zein-degrading bacteria in an attempt to obtain zein-degrading protease. Methods and Results:, Soil bacteria were screened by formation of a clear zone on zein plates. Characterization of a zein-degrading bacterium indicated a taxonomic affiliation to Bacillus pumilus, and was named MS-1 strain. The strain produced two different types of extracellular proteases, BPP-A and BPP-B. In this study, we purified and characterized BPP-A because it exhibited a higher ability to hydrolyze zein than BPP-B. When casein was used as the substrate, the optimal pH for BPP-A was 11·0. In BPP-A, zein was better substrate than casein at pH 13·0, whereas casein was better one than zein at pH 11·0. The bppA gene encoded a 383-amino acid pre-pro form of BPP-A, and mature BPP-A contained 275 amino acid residues. It was concluded that BPP-A belonged to the subtilisin family. Conclusion:, A zein-degrading bacterium assigned to B. pumilus produced two different types of extracellular proteases, BPP-A and BPP-B. BPP-A exhibited an ability to hydrolyze zein in an extreme alkaline condition. Significance and Impact of the Study:, This is a first report on screening for zein-degrading micro-organisms. The subtilisin-like protease BPP-A is possible to utilize as an industrial enzyme for the production of zein hydrolysates. [source] Flow Injection Analysis of Sulfide Using a Cinder/Tetracyano Nikelate Modified Screen-Printed ElectrodeELECTROANALYSIS, Issue 9 2005Jyh-Myng Zen Abstract Flow injection analysis (FIA) of sulfide is presented using a screen-printed carbon electrode modified with a cinder/tetracyano nickelate hybrid (designated as cinder/NiTcSPE). Hybridization of NiTc was achieved in iron-enriched industrial waste cinder material through the bimetallic formation of FeIII[NiII(CN)4]. The electrocatalytic oxidation of sulfide is mediated by the higher oxidation state of Ni in this hybrid-bimetallic complex. The system shows a detection limit (S/N=3) of 0.06,,M and a linear working range up to 1,mM in pH,10, 0.1,M KCl solution. Taking into account the relatively low volatility of the analyte in alkaline conditions, the system is ideally suited for the accurate detection of sulfide. The response of the electrode to sulfide is highly reproducible, thereby offering the potential development of a disposable amperometric sensor for sulfide. Selective detection of sulfide in cigarette smoke is presented in this study as an example of a real sample application. [source] Search of Microorganisms that Degrade PAHs under Alkaline ConditionsENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 4 2004A. Gerbeth Abstract Bacterial strains were enriched from building rubble contaminated with polycyclic aromatic hydrocarbons (PAHs). These strains were studied as an inoculum in bioremediation processes with contaminated building rubble. The selection criteria for the bacteria were broad profiles in PAH degradation, stable expression of the traits and tolerance to alkaline conditions. Various strains of Micrococcus sp., Dietzia sp., Rhodococcus sp. and Pseudomonas sp. met the selection criteria. In general, degradative activity was limited at higher pH values. Strains of Micrococcus were suitable for practical use as complete degradation of various PAHs was observed at pH values exceeding 10. Strains of Dietzia sp. showed broad PAH degradation profile, but in some cases degradation came to a halt leaving some of the PAHs unutilized. With Dietzia sp. this could be due to inhibitory effects from the accumulation of toxic PAH metabolic products and/or growth-limiting media conditions. [source] Association of europium(III), americium(III), and curium(III) with cellulose, chitin, and chitosanENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2006Takuo Ozaki Abstract The association of trivalent f-elements,Eu(III), Am(III), and Cm(III),with cellulose, chitin, and chitosan was determined by batch experiments and time-resolved, laser-induced fluorescence spectroscopy (TRLFS). The properties of these biopolymers as an adsorbent were characterized based on speciation calculation of Eu(III). The adsorption study showed that an increase of the ionic strength by NaCl did not affect the adsorption kinetics of Eu(III), Am(III), and Cm(III) for all the biopolymers, but the addition of Na2CO3 significantly delayed the kinetics because of their trivalent f-element complexation with carbonate ions. It also was suggested from the speciation calculation study that all the biopolymers were degraded under alkaline conditions, leading to their masking of the adsorption of Eu(III), Am(III), and Cm(III) on the nondegraded biopolymers. The masking effect was higher for cellulose than for chitin and chitosan, indicating that of the three, cellulose was degraded most significantly in alkaline solutions. Desorption experiments suggested that some portion of the adsorbed Eu(III) penetrated deep into the matrix, being isolated in a cavity-like site. The TRLFS study showed that the coordination environment of Eu(III) is stabilized mainly by the inner spherical coordination in chitin and by the outer spherical coordination in chitosan, with less association in cellulose in comparison to chitin and chitosan. These results suggest that the association of these biopolymers with Eu(III), Am(III), and Cm(III) is governed not only by the affinity of the functional groups alone but also by other factors, such as the macromolecular steric effect. The association of degraded materials of the biopolymers also should be taken into consideration for an accurate prediction of the influence of biopolymers on the migration behavior of trivalent f-elements. [source] Facile and Reproducible Synthesis of Nanostructured Colloidal ZnO Nanoparticles from Zinc Acetylacetonate: Effect of Experimental Parameters and Mechanistic InvestigationsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 33 2009Alessia Famengo Abstract A facile and reproducible route to nanostructured colloidal ZnO nanoparticles was developed by controlled hydrolysis and condensation of zinc acetylacetonate in alkaline conditions. By reaction of an ethanolic solution of Zn(acac)2 with NaOH in a 1:2 molar ratio, after reflux, ZnO spherical nanoparticles were obtained that displayed a homogeneous size distribution; particle diameters ranged from 6 to 10 nm, as evidenced by transmission electron microscopy (TEM) analysis. The same reaction was carried out also in water, glycerol and 1,2-propanediol, to investigate the effect of the solvent viscosity and dielectric constant on the final features of the obtained material. Irrespective of the nature of the solvent, X-ray diffraction (XRD) analysis shows the formation ofhexagonal ZnO, whereas the presence of residual unreacted Zn(acac)2 could be ruled out. Indeed, different particle sizes and very different morphologies were obtained. Also the reflux step was shown to be a key factor in avoiding the fast precipitation of a floc and achieving a pure compound, which was isolated and thoroughly characterised. The composition of the obtained ZnO was determined by elemental analysis, X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA), showing the formation of pure ZnO. IR spectroscopy evidenced the presence of adsorbed organic ligands on the colloid surfaces. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) revealed the presence of medium- to high-strength acidic sites on the ZnO surface. To gain a deeper insight into the formation mechanisms of these nanostructures, time-resolved UV/Vis and XAS studies were performed on the ethanol solution used for the synthesis of the oxide and also on the solid specimen, obtained after the refluxing step. No remarkable changes could be evidenced in the solution after the addition of an understoichiometric amount of NaOH, but the growth of the ZnO nanoparticles could be followed by UV/Vis spectra. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Heterogeneous aerobic benzene-degrading communities in oxygen-depleted groundwatersFEMS MICROBIOLOGY ECOLOGY, Issue 2 2006Anne Fahy Abstract A sandstone aquifer beneath a petrochemicals plant (SIReN site, UK) is heterogeneously contaminated with benzene and oxygen-depleted. Despite low redox potentials in three of the most contaminated groundwaters (benzene concentrations from 17.8 to 294 mg L,1), we observed aerobic benzene degradation in microcosms, indicating the presence in situ of a latent community of obligate aerobic microorganisms or an active community of facultative aerobes responding rapidly to oxygen ingress. Moreover, benzene degradation occurred at the ambient pH of 8.9 and 9.4, considerably more alkaline conditions than previously reported. 16S rRNA analyses showed that the groundwater microcosm communities were distinct from each other, despite sharing the function of aerobic benzene degradation. From DNA fingerprinting, one consortium was dominated by Acidovorax spp., another by Pseudomonas spp.; these benzene-degrading consortia were similar to the in situ communities, perhaps indicating that these organisms are active in situ and degrading benzene microaerophilically or by denitrification. Conversely, in the third sample, benzene degradation occurred only after the community changed from a Rhodoferax -dominated community to a mix of Rhodococcus and Hydrogenophaga spp. Four of the main benzene-degrading strains were brought into culture: Hydrogenophaga and Pseudomonas spp., and two strains of Rhodococcus erythropolis, a ubiquitous and metabolically versatile organism. [source] Extremely Alkaline (pH > 12) Ground Water Hosts Diverse Microbial CommunityGROUND WATER, Issue 4 2006George S. Roadcap Chemically unusual ground water can provide an environment for novel communities of bacteria to develop. Here, we describe a diverse microbial community that inhabits extremely alkaline (pH > 12) ground water from the Lake Calumet area of Chicago, Illinois, where historic dumping of steel slag has filled in a wetland. Using microbial 16S ribosomal ribonucleic acid gene sequencing and microcosm experiments, we confirmed the presence and growth of a variety of alkaliphilic ,-Proteobacteria, Bacillus, and Clostridium species at pH up to 13.2. Many of the bacterial sequences most closely matched those of other alkaliphiles found in more moderately alkaline water around the world. Oxidation of dihydrogen produced by reaction of water with steel slag is likely a primary energy source to the community. The widespread occurrence of iron-oxidizing bacteria suggests that reduced iron serves as an additional energy source. These results extend upward the known range of pH tolerance for a microbial community by as much as 2 pH units. The community may provide a source of novel microbes and enzymes that can be exploited under alkaline conditions. [source] Geochemistry of Extremely Alkaline (pH > 12) Ground Water in Slag-Fill AquifersGROUND WATER, Issue 6 2005George S. Roadcap Extremely alkaline ground water has been found underneath many shuttered steel mills and slag dumps and has been an impediment to the cleanup and economic redevelopment of these sites because little is known about the geochemistry. A large number of these sites occur in the Lake Calumet region of Chicago, Illinois, where large-scale infilling of the wetlands with steel slag has created an aquifer with pH values as high as 12.8. To understand the geochemistry of the alkaline ground water system, we analyzed samples of ground water and the associated slag and weathering products from four sites. We also considered several potential remediation schemes to lower the pH and toxicity of the water. The principal cause of the alkaline conditions is the weathering of calcium silicates within the slag. The resulting ground water at most of the sites is dominated by Ca2+ and OH, in equilibrium with Ca(OH)2. Where the alkaline ground water discharges in springs, atmospheric CO2 dissolves into the water and thick layers of calcite form. Iron, manganese, and other metals in the metallic portion of the slag have corroded to form more stable low-temperature oxides and sulfides and have not accumulated in large concentrations in the ground water. Calcite precipitated at the springs is rich in a number of heavy metals, suggesting that metals can move through the system as particulate matter. Air sparging appears to be an effective remediation strategy for reducing the toxicity of discharging alkaline water. [source] 7-Halogenated 7-Deaza-2,-deoxyxanthine 2,-DeoxyribonucleosidesHELVETICA CHIMICA ACTA, Issue 6 2004Frank Seela The synthesis of the 7-halogenated derivatives 1b (7-bromo) and 1c (7-iodo) of 7-deaza-2,-deoxyxanthosine (1a) is described. A partial Br,I exchange was observed when the demethylation of 6-methoxy precursor compound 4b was performed with Me3SiCl/NaI. This reaction is circumvented by the nucleophilic displacement of the MeO group under strong alkaline conditions. The halogenated 7-deaza-2,-deoxyxanthosine derivatives 1b,c show a decreased S -conformer population of the sugar moiety compared to the nonhalogenated 1a. They are expected to form stronger triplexes when they replace 1a in the 1,dA,dT base triplet. [source] Hydrolysis of an isolable selenoseleninate under acidic and alkaline conditionsHETEROATOM CHEMISTRY, Issue 4 2001Akihiko Ishii Acid-catalyzed hydrolysis of a selenoseleninate [TripSe(O)SeTrip](Trip = 9-triptycyl) in 2 M HClO4 -1,4-dioxane at room temperature yielded the selenenic acid (TripSeOH). Alkaline hydrolysis of TripSe(O)SeTrip gave the diselenide (TripSeSeTrip) and the seleninic acid (TripSeO2H), where air oxidations of the resulting selenol (TripSeH) and TripSeOH occur at a considerable rate. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:198,203, 2001 [source] Purification and characterization of two bacteriocins produced by lactic acid bacteria isolated from Mongolian airagJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2006B. Batdorj Abstract Aims:, The aim of this study was to isolate and identify bacteriocin-producing lactic acid bacteria (LAB) issued from Mongolian airag (traditional fermented mare's milk), and to purify and characterize bacteriocins produced by these LAB. Methods and Results:, Identification of the bacteria (Enterococcus durans) was carried out on the basis of its morphological, biochemical characteristics and carbohydrate fermentation profile and by API50CH kit and 16S rDNA analyses. The pH-neutral cell-free supernatant of this bacterium inhibited the growth of several Lactobacillus spp. and food-borne pathogens including Escherichia coli, Staphylococcus aureus and Listeria innocua. The antimicrobial agent (enterocin A5-11) was heat stable and was not sensitive to acid and alkaline conditions (pH 2,10), but was sensitive to several proteolytic enzymes. Its inhibitory activity was completely eliminated after treatment with proteinase K and , -chymotrypsin. The activity was however not completely inactivated by other proteases including trypsin and pepsin. Three-step purification procedure with high recovery yields was developed to separate two bacteriocins. The applied procedure allowed the recovery of 16% and 64% of enterocins A5-11A and A5-11B, respectively, present in the culture supernatant with purity higher than 99%. SDS-PAGE analyses revealed that enterocin A5-11 has a molecular mass of 5000 Da and mass spectrometry analyses demonstrates molecular masses of 5206 and 5218 Da for fractions A and B, respectively. Amino acid analyses of both enterocins indicated significant quantitative difference in their contents in threonine, alanine, isoleucine and leucine. Their N -termini were blocked hampering straightforward Edman degradation. Conclusions:, Bacteriocins A5-11A and B from Ent. durans belong to the class II of bacteriocins. Significance and Impact of the Study:, Judging from molecular masses, amino acid composition and spectrum of activities, bacteriocins A5-11A and B from Ent. durans show high degree of similarity with enterocins L50A and L50B isolated from Enterococcus faecium (Cintas et al. 1998, 2000) and with enterocin I produced by Ent. faecium 6T1a, a strain originally isolated from a Spanish-style green olive fermentation (Floriano et al. 1998). [source] Antimicrobial finishing of regular and modified nylon-6 fabricsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2008S. E. Shalaby Abstract A simple, efficient, and practically applicable functional approach for improvement antimicrobial properties of nylon-6 fabrics and increase the washing durability of biofunctions was developed. This finishing approach is based on grafting of the fabrics with methacrylic acid (MAA) to create additional carboxylic groups in nylon-6 macromolecules, followed by subsequent reaction with dimethylalklbenzyl ammonium chloride (DMABAC) solution under alkaline conditions. The carboxylic groups react with cationic agent through ionic interaction, which led to the immobilization of QAS on nylon-6 fabrics. This immobilization was proofed through determination of nitrogen content, applying scanning electron microscopy (SEM), and FTIR microscopy. The effect of treatment conditions on salt uptake (SUT) on nylon-6 fabrics and reaction efficiency (RE) was investigated. The antimicrobial assessment of regular and grafted with PMAA nylon-6 fabrics treated with DMABAC revealed that both types of fabrics are characterized before washing, by quite strong biocide effect on Bacillus mycoides, Escherichia coli and Candida albicans. The role of grafting nylon-6 fabrics before treatment with salt on durability of antimicrobial functions seems to be more significant as the samples were repeatedly washed. Even after Laundring 10 times the grafted samples could still provide 80%, 100%, and 87.5% microbial reduction against B. mycoides, E. coli and C. albicans, respectively, in contrast with 42.6%, 65.6%, and 42.5% in case of regular nylon-6 fabrics. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008. [source] Preparation and applications of novel fluoroalkyl end-capped sulfonic acid oligomers,silica gel polymer hybridsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007Kazuo Sasazawa Abstract Fluoroalkyl end-capped 2-methacryloxyethanesulfonic acid homo-oligomer [RF,(MES)n,RF] and 2-methacryloxyethanesulfonic acid,N,N -dimethylacrylamide co-oligomers [RF,(MES)x,(DMAA)y,RF] reacted with tetraethoxysilane (TEOS) under acidic conditions to afford RF,(MES)n,RF homo-oligomer,SiO2 polymer hybrid and RF,(MES)x,(DMAA)y,RF co-oligomer,SiO2 polymer hybrid, respectively. Thermogravimetric,mass spectra showed that the thermal stability of RF,(MES)n,RF homo-oligomer,SiO2 polymer hybrid was superior to that of traditionally well-known perfluorinated ion exchange polymers such as Nafion 112 (TR). The sol solutions of the fluorinated co-oligomer,SiO2 polymer hybrid were applied to the surface modification of glass to exhibit not only a strong oleophobicity imparted by fluorine but also a good hydrophilicity on the glass surface. On the other hand, RF,(MES)x,(DMAA)y,RF co-oligomer reacted with TEOS in the presence of a variety of silica nanoparticles (mean diameters: 11,95 nm) under alkaline conditions to afford fluoroalkyl end-capped oligomers,silica nanoparticles (mean diameters: 32,173 nm) with a good dispersibility and stability in methanol. Similarly, a variety of fluorinated oligomers containing sulfo groups,silica nanoparticles were prepared by the homo- and co-oligomerizations of fluoroalkanoyl peroxides with 2-methacryloxyethane sulfonic acid (MES) and comonomers such as N,N -dimethylacrylamide (DMAA) and acryloylmorpholine (ACMO) in the presence of silica nanoparticles. Interestingly, these isolated fluorinated particle powders were found to afford nanometer size-controlled colloidal particles with a good redispersibility and stability in aqueous and organic media such as methanol. These fluorinated nanoparticles containing sulfo groups were also applied to an excellent heterogeneous catalyst for Bronsted acid-catalyzed transformations. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 110,117, 2007 [source] Effect of salinity on denitrification under limited single carbon source by Marinobacter sp. isolated from marine sedimentJOURNAL OF BASIC MICROBIOLOGY, Issue 3 2010Miyo Nakano Abstract Marinobacter comprises Gram-negative, aerobic, motile, and rod-shaped bacteria within the ,-subclass of the Proteobacteria and is known to be halophilic or halotolerant, heterotrophic neutrophile. Two strains classified as belonging to Marinobacter, named PAD-2 and SeT-1, were isolated from marine sediment. The most closely related species of PAD-2 and SeT-1 are M. alkaliphilus and M. guinea, respectively. The strain PAD-2 exhibited remarkably higher denitrification at concentrations of 0.5 to 1 M NaCl (3,6% w/w) than at other salinities (2 and 3 M NaCl, 12,18% w/w), and optimal denitrification was observed in media with 0.5 M NaCl. The effect of pH on denitrification by strain PAD-2 was also examined, and the optimum denitrification occurred at neutral pH rather than under alkaline conditions. Overall, strain PAD-2 appears to be a novel halotolerant species belonging to the genus Marinobacter that shares many characteristics, such as substrate utilization profile and optimum NaCl concentration for growth with M. alkaliphilus. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The evolutionary species pool hypothesis and patterns of freshwater diatom diversity along a pH gradientJOURNAL OF BIOGEOGRAPHY, Issue 3 2005Jason Pither Abstract Aim, To interpret the unimodal relationship between diatom species richness and lake pH within the context of the evolutionary species pool hypothesis (SPH). We test the following primary prediction arising from the SPH: the size of the potential species pool (PSP) will increase along a gradient representing the historical commonness of different pH environments (pH commonness). To do this we assume that the present-day spatial dominance of near-neutral pH conditions compared with acidic and alkaline conditions reliably mimics the relative spatial availabilities of historical pH conditions among freshwater lakes. We also determine whether local richness represents a constant proportion of PSP size along the pH commonness gradient. Location, Two hundred and thirty-four lakes distributed over a 405,000 km2 region of the north-eastern United States of America. Methods, Sediment diatom morphospecies lists and pH data were acquired from the US Environmental Protection Agency's Environmental Monitoring and Assessment Program (EMAP) website. Using 248 morphospecies that occurred in at least 10 of the 234 lakes, four different measures of PSPs were calculated along the pH gradient. Local species richness was equated with the number of species occurring within the lake. Alpha diversity was equated with the average species richness of lakes with similar pH values. A combination of statistical methods were employed, including correlations, quadratic regression and piecewise regression. Results, PSP size increased significantly with pH commonness for all four measures of PSP size, thus supporting the primary prediction of the evolutionary SPH. Local richness comprised a larger proportion of the PSP within acidic lakes than within circumneutral lakes. Alpha diversity and lake species richness both increased significantly with pH commonness, but the former did so in a two-step fashion. We test and reject several alternative contemporary time-scale explanations for our findings. Main Conclusions, Our findings are consistent with the hypothesis that diatom taxonomic richness is presently lower within acidic and highly alkaline lakes than in circumneutral lakes owing to the limited opportunity in space and/or time for the evolution of suitably adapted species. Whereas ecological processes can explain why certain species are excluded from particular habitats, e.g. acidic lakes, they cannot account for why so few species are adapted to those habitats in the first place. [source] Poly(glutamic acid) poly(ethylene glycol) hydrogels prepared by photoinduced polymerization: Synthesis, characterization, and preliminary release studies of protein drugsJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2002Zhiqiang Yang Abstract A class of new biodegradable hydrogels based on poly(ethylene glycol) methacrylate-graft-poly(glutamic acid) and poly(ethylene glycol) dimethacrylate was synthesized by photoinduced polymerization. Because all the polymeric constituents were highly hydrophilic, crosslinking could be performed in aqueous solutions. This type of crosslinked hydrogel was prepared by modifying a select number of acidic side-groups on poly(glutamic acid) with poly(ethylene glycol) methacrylate. These modified chains were then crosslinked in the presence of poly(ethylene glycol) dimethacrylate under a photoinduced polymerization at a wavelength of 365 nm. Swelling experiments were conducted to study the crosslinking density, pH-responsive behavior, and degradation of the hydrogel. Results showed that the degree of swelling of this type of hydrogels increased as the crosslinker concentration (or density) was reduced. Because of the presence of acidic side chains on poly(glutamic acid), swelling behavior was found to be pH-responsive, increasing at high pH in response to the increase in the amount of ionized acidic side chains. The degradation rate of these hydrogels also varied with pH. More rapid degradation was observed under stronger alkaline conditions because of the hydrolysis of the ester bonds between the crosslinker and the polymer backbone. Practically useful degradation rates could be achieved for such hydrogels under physiological conditions. Drug release rates from these hydrogels were found to be proportional to the protein molecular weight and the crosslinker density; increasing at lower protein molecular weight or crosslinker density. The preliminary findings presented in this article suggest that this class of biodegradable hydrogels could be an attractive avenue for drug delivery applications. The specific photoinduced crosslinking chemistry used would permit hydrogels to be synthesized in existence of the entrapped macromolecular drugs including peptides, proteins, and cells. In addition, the rapid feature of this polymerization procedure along with the ability to perform hydrogel synthesis and drug loading in an aqueous environment would offer great advantages in retaining drug activity during hydrogel synthesis. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 14,21, 2002 [source] The Green Oat Story: Possible Mechanisms of Green Color Formation in Oat Products during CookingJOURNAL OF FOOD SCIENCE, Issue 6 2009D.C. Doehlert ABSTRACT:, Consumers occasionally report greenish colors generated in their oat products when cooking in tap water. Here we have investigated pH and ferrous (Fe2+) ion as possible mechanisms for this color change. Steel-cut oat groats can turn brown-green color when cooked in alkaline conditions (pHs 9 to 12). Extraction of this color with methanol, and high-pressure liquid chromatography indicated a direct association of this color with the phenolic acid or avenanthramide content of the oat. The presence of 50 mM NaHCO3 in water will cause oat/water mixtures to turn alkaline when cooked as CO2 is driven off, generating OH, ion. Although tap water rarely, if ever, contains so much bicarbonate, bicarbonate is used as a leavening agent in baking applications. Industrial interests using baking soda or alkaline conditions during oat processing should be aware of possible off color generation. We have also found that as little as 10 ppm Fe2+ will turn oat products gray-green when cooked. The aleurone stained darker than the starchy endosperm. Other divalent cations, such as Ca2+ or Mg2+ had no effect on cooked oat color. As much as 50 ppm Fe2+ may be found in freshly pumped well water, but Fe2+ reacts quickly with oxygen and precipitates as Fe(OH)3. Thus, some freshly pumped well water may turn oats green when cooked, but if the water is left under atmospheric conditions for several hours, no discoloration will appear in the cooked oats. [source] Binding Properties of 2-Pentyl Pyridine to Soy Protein as Measured by Solid Phase MicroextractionJOURNAL OF FOOD SCIENCE, Issue 1 2002A. Zhou ABSTRACT: The binding properties of 2-pentyl pyridine (2-pp) were investigated for soybean protein isolates (SPI) and the beta-conglycinin and glycinin soy protein fractions. The glycinin fraction had the highest binding affinities for 2-pp, followed by beta-conglycinin fraction, and then SPI. More 2-pp was bound by SPI and beta-conglycinin or glycinin fractions under alkaline conditions than under neutral conditions, which exhibited more binding than acidic conditions. More 2-pp was also bound at high temperature (74 °C) than at 25 °C, but greater binding affinity of 2-pp was observed at 4 °C than at 25 °C. With increased NaCl concentrations, the binding affinity of 2-pp decreased. Exposure to UV light increased binding of 2-pp to all types of soy protein. [source] Location of Disulfide bonds in mature ,- L;-fucosidase from peaJOURNAL OF PEPTIDE SCIENCE, Issue 6 2001Anna Codina Abstract Fuc-9 is the mature form of a vacuolar ,- L;-fucosidase enzyme which seems to play an important role in plant growth regulation. Fuc-9 is a 202-residue protein containing five Cys residues located at positions 64, 109, 127, 162 and 169. In this study, the disulfide structure of Fuc-9 was determined by MALDI-TOF mass spectrometry (MS), with minimal clean-up of the samples and at a nanomolar scale. Two strategies, based on a specific chemical cleavage (with 2-nitro-5-thiocyanobenzoic acid and alkaline conditions) at the Cys residues and modification of Cys residues by acrylamide/deuterium labeled acrylamide alkylation, were used. Using these methods, the disulfide pairings Cys64-Cys109 and Cys162-Cys169 could be established. The advantages and limitations of our experimental approach are discussed. Copyright © 2001 European Peptide Society and John Wiley & Sons, Ltd. [source] Facile synthesis, characterization, and potential applications of two kinds of polymeric pH indicators: Phenolphthalein formaldehyde and o -cresolphthalein formaldehydeJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 5 2005Zhihong Liu Abstract Two kinds of applicable polymeric pH indicators were synthesized by the reaction of phenolphthalein and o -cresolphthalein with formaldehyde under alkaline conditions by a one-pot method. The synthesized products were fully characterized with Fourier transform infrared, 1H NMR, ultraviolet,visible spectroscopy, and gel permeation chromatography. The results indicated that the reaction was a typical phenol formaldehyde reaction. The dosage of formaldehyde and the reaction time were well controlled to obtain soluble polymers, instead of crosslinked products. The polymeric-pH-indicator-immobilized poly(vinyl alcohol) (PVA) membranes were easily fabricated and had good long-term stability under highly basic conditions and a fast equilibrium response. Moreover, the phenolphthalein formaldehyde immobilized PVA membrane had a linear response from pH 10.0 to 14.0, and so it has promise as a optical transducer for high pH value determinations. The o -cresolphthalein formaldehyde immobilized PVA membrane had a nonlinear response from pH 9.0 to 13.0. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1019,1027, 2005 [source] Synthesis and characterization of alkylated N -vinylformamide monomers and their polymersJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 19 2004Lianjun Shi Abstract N -alkyl- N -vinylformamide monomers (alkyl: n -butyl, hexyl, decyl, and dodecyl) are synthesized in two steps: first, preparation of N -vinylformamide potassium salt by the reaction of N -vinylformamide (NVF) with potassium t -butoxide, then reaction with alkyl bromide. All four monomers are liquid and are characterized by IR, 1H NMR, 13C NMR, and mass spectra. They exist as rotomers in solution and a 2D NOE experiment on the N -hexyl containing polymer shows the E isomer to be favored. The polymerizability of the four monomers is from good to fair, depending upon the length of alkyl chain on the N -atom--the longer the chain length, the lower lower the polymerizability of monomer. The hydrolysis of poly(N -hexyl- N -vinylformamide) and poly(N -dodecyl- N -vinylformamide) under acidic and basic conditions was examined. Studies show that hydrolytic cleavage of formyl groups of poly (N -alkylated- N -vinylformamide) depends on the hydrophobicity of the alkyl substituent on the N -atom under acidic conditions; both polymers were hydrolyzed to only a minor extent under alkaline conditions. The N -alkylated monomers can copolymerize with NVF and demonstrate amphiphilic properties. The copolymers demonstrate a critical aggregation concentration above which they can solubilize a water insoluble dye; the N -hexyl containing copolymer stabilizes a castor oil-in-water emulsion. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4994,5004, 2004 [source] Identification of arid phases during the last 50,cal. ka BP from the Fuentillejo maar-lacustrine record (Campo de Calatrava Volcanic Field, Spain),JOURNAL OF QUATERNARY SCIENCE, Issue 7 2010Juana Vegas Abstract Geochemical (element analysis, molecular analysis of organic compounds), physical, palynological, mineralogical and sedimentary facies analysis were performed to characterise the sedimentary record in Fuentillejo maar-lake in the Central Spanish Volcanic Field of Campo de Calatrava, in order to reconstruct the palaeoenvironmental and palaeoclimatic processes which controlled vegetation patterns and deposition of different sedimentary facies. The upper 20,m of core FUENT-1 show variations in clastic input, water chemistry, vegetation and organic fraction sources in the lake throughout the Late Pleistocene and Holocene. The temporal framework provided by 14C accelerator mass spectrometry dating allows assigning the sequence to the last 50,cal. ka BP. Arid phases identified in the FUENT-1 sequence are correlated to Heinrich events (HE) and to stadials of the Dansgaard/Oeschger (D/O) cycles. Siliciclastic facies with high magnetic susceptibility values, high Juniperus pollen content, a low Paq index (aquatic macrophysics proxy index), a decrease in the relative percentage of the n -C27 and an increase in the n -C31 alkanes are indicative of arid and colder climatic events related to HE 2, HE 1 and the Younger Dryas (YD). Similar short cold and arid phases during the Holocene were identified at 9.2,8.6, 7.5,7 and 5.5,5,cal. ka BP. In dolomite,mud facies, the pollen data show an increase in the herbs component, mainly , Chenopodiaceae, Artemisia and Ephedra , steppe taxa; a low Paq index, a decrease in the relative percentage of the n -C27 alkane and an increase in the n -C31 alkane are also observed. This facies was probably the result of lower lake levels and more saline,alkaline conditions, which can be interpreted as linked to arid,warm periods. These warm and arid phases were more frequent during Marine Isotope Stage (MIS) 3 and the interstadials of MIS 2. HE 4, HE 2, HE 1 and the YD in core FUENT-1 were immediately followed by increases of warm steppe pollen assemblages that document rapid warming similar to the D/O cycles but do not imply increasing humidity in the area. Fuentillejo hydrology is controlled by changes in the atmospheric and oceanic systems that operated on the North Atlantic region at millennial scale during the last 50,cal. ka BP. Copyright © 2009 John Wiley & Sons, Ltd. [source] | |||||||||||||||||||||||||||||||||||||