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NaCl Solution (nacl + solution)
Kinds of NaCl Solution Selected AbstractsBismuth Film Electrode as an Alternative for Mercury Electrodes: Determination of Azo Dyes and Application for Detection in Food StuffsELECTROANALYSIS, Issue 21 2007Benoît Claux Abstract Bismuth electrodes were investigated and exhibit electrochemical properties similar to mercury electrodes but with much lower toxicity. An electrochemical application of bismuth film modified glassy carbon electrode for azo dyes determination was investigated. The plating step was optimized in order to achieve its analytical efficiency. A plating potential of ,0.9,V in a solution of 200,mg/L Bi(NO3)3, 0.5,M HNO3 for 100,s yields to a suitable electrode (in terms of stability and detection). Azo dyes such as azorubine (i.e., carmoisine, E122), amaranth (E123), ponceau 4R (i.e., new coccine, E124) and allura red (E129) were determined by differential pulse voltammetry in a NaCl solution in the concentration range of few ppm to 100 ppm. The reproducibility of the signal, characterized by the relative standard deviation, was found to be less than 5%, the detection and quantification limits were few mg/L. The influence of other food components on the signal was studied and the applicability was tested on real beverages samples. [source] The Solid State Electrochemistry of Dysprosium(III) Hexacyanoferrate(II)ELECTROANALYSIS, Issue 17 2005Ping Wu Abstract A new electroactive polynuclear inorganic compound of rare earth metal hexacyanoferrate, dysprosium hexacyanoferrate (DyHCF), was prepared chemically and characterized using techniques of FTIR spectroscopy, thermogravimetric analysis (TGA), UV-vis spectrometry and X-ray photoelectron spectroscopy (XPS) etc. The cyclic voltammetric behavior of DyHCF mechanically attached to the surface of graphite electrode was well defined and exhibited a pair of redox peaks with the formal potential of 217,mV (vs. SCE) at a scan rate of 100,mV/s in 0.2,M NaCl solution and the redox peak currents increased linearly with the square root of the scan rates. [source] Dual stacking of unbuffered saline samples, transient isotachophoresis plus induced pH junction focusingELECTROPHORESIS, Issue 10 2003Sang-Hee Shim Abstract A dual stacking mechanism based on transient isotachophoresis (TITP) and induced pH junction focusing is demonstrated as a means to increase the concentration sensitivity in capillary electrophoresis of highly saline samples. When stacking was carried out with an unbuffered saline sample of fluorescein between two zones of low mobility background electrolyte at high pH under an electric field of reverse polarity, two transient peaks at both boundaries of the sample zone were observed. One peak at the rear boundary could be inferred as a transient isotachophoretic stacked zone. Through computer simulations of an unbuffered sample with a high concentration of sodium chloride, we showed that the fast moving zones of sodium and chloride ions induced pH changes at both boundaries to satisfy the electroneutrality condition and that the peak at the front boundary was due to the induced pH junction. To verify the pH changes, an indicator, thymol blue, was added to an NaCl solution and the color changes under an electric field were observed. The proposed mechanism was supported by observing the dual stacking procedure for an unbuffered sample of 4-nitrophenol and measuring additional sensitivity enhancements by dual stacking for ten weakly acidic compounds. For the ten analytes including nucleoside phosphates, every dual stacking of an unbuffered sample exhibited an additional enhancement up to 86% larger than that of usual transient isotachophoresis of the corresponding buffered sample without loss of separation efficiency and reproducibility. Therefore, it would be useful to skip over buffering in sample preparation for TITP, contrary to the general recommendation. [source] Environmental Behavior and Stress Corrosion Characteristics of Nano/Sub-Micron E950 Aluminum Alloy,ADVANCED ENGINEERING MATERIALS, Issue 11 2009Eli Aghion The corrosion performance and stress corrosion resistance of E950 Aluminum alloy with nano/sub-micron structure were evaluated in 3.5% NaCl solution. The results obtained indicated that the corrosion and stress corrosion resistance of E950 alloy were relatively reduced compared to that of the conventional coarse-grained alloy (Al,4.65%Mg). In particular, the inherently improved ultimate tensile strength of E950 alloy was significantly decreased under stress corrosion conditions. [source] The effect of pitting corrosion on fatigue lifeFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 7 2000Dolley Fatigue testing of pre-pitted 2024-T3 aluminium alloy specimens is performed in laboratory air at 22 °C and 40% RH to characterize the effect of pitting corrosion on fatigue life. Specimens, pre-corroded in a 0.5 M NaCl solution from 48 to 384 h, have fatigue lives that are reduced by more than one order of magnitude after 384 h pre-corrosion as compared to those of uncorroded specimens. The reduction in fatigue life is interpreted in terms of the influence of the time of exposure to the corrosive environment or pit size. The crack-nucleating pit sizes, ranging from 20 to 70 ,m, are determined from post-fracture examinations by scanning electron microscopy. Fatigue lives are estimated using a fracture mechanics approach and are shown to be in good agreement with the actual data. A probabilistic analysis shows that the distribution of fatigue life is strongly correlated to the distribution in nucleating pit size. [source] Corrosion fatigue behaviour of a 15Cr-6Ni precipitation-hardening stainless steel in different tempersFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 6 2000C.-K. Lin Systematic fatigue experiments, including both high-cycle axial fatigue (S,N curves) and fatigue crack growth (FCG, da/dN,,K curves), were performed on a precipitation-hardening martensitic stainless steel in laboratory air and 3.5 wt% NaCl solution. Specimens were prepared in three tempers, i.e. solution-annealed (SA), peak-aged (H900) and overaged (H1150) conditions, to characterize the effects of ageing treatment on the corrosion fatigue (CF) resistance. S,N results indicated that fatigue resistance in all three tempers was dramatically reduced by the aqueous sodium chloride environment. In addition, the smooth-surface specimens in H900 temper exhibited longer CF lives than the H1150 ones, while those in SA condition stood in between. However, for precracked specimens, the H1150 temper provided superior corrosive FCG resistance than the other two tempers. Comparison of the S,N and FCG curves indicated that early growth of crack-like defects and short cracks played the major role in determining the CF life for smooth surface. The differences in the CF strengths for the S,N specimens of the given three tempers were primarily due to their inherent differences in resistance to small crack growth, as they were in the air environment. [source] Calcite-specific coupling protein in barnacle underwater cementFEBS JOURNAL, Issue 24 2007Youichi Mori The barnacle relies for its attachment to underwater foreign substrata on the formation of a multiprotein complex called cement. The 20 kDa cement protein is a component of Megabalanus rosa cement, although its specific function in underwater attachment has not, until now, been known. The recombinant form of the protein expressed in bacteria was purified in soluble form under physiological conditions, and confirmed to retain almost the same structure as that of the native protein. Both the protein from the adhesive layer of the barnacle and the recombinant protein were characterized. This revealed that abundant Cys residues, which accounted for 17% of the total residues, were in the intramolecular disulfide form, and were essential for the proper folding of the monomeric protein structure. The recombinant protein was adsorbed to calcite and metal oxides in seawater, but not to glass and synthetic polymers. The adsorption isotherm for adsorption to calcite fitted the Langmuir model well, indicating that the protein is a calcite-specific adsorbent. An evaluation of the distribution of the molecular size in solution by analytical ultracentrifugation indicated that the recombinant protein exists as a monomer in 100 mm to 1 m NaCl solution; thus, the protein acts as a monomer when interacting with the calcite surface. cDNA encoding a homologous protein was isolated from Balanus albicostatus, and its derived amino acid sequence was compared with that from M. rosa. Calcite is the major constituent in both the shell of barnacle base and the periphery, which is also a possible target for the cement, due to the gregarious nature of the organisms. The specificity of the protein for calcite may be related to the fact that calcite is the most frequent material attached by the cement. [source] In vitro antimicrobial activity of several concentrations of sodium hypochlorite and chlorhexidine gluconate in the elimination of Enterococcus faecalisINTERNATIONAL ENDODONTIC JOURNAL, Issue 6 2001B. P. F. A. Gomes Abstract Aim The aim of this study was to assess, in vitro, the effectiveness of several concentrations of NaOCl (0.5%, 1%, 2.5%, 4% and 5.25%) and two forms of chlorhexidine gluconate (gel and liquid) in three concentrations (0.2%, 1% and 2%) in the elimination of E. faecalis. Methodology A broth dilution test using 24-well cell culture plates was performed and the time taken for the irrigants to kill bacterial cells was recorded. Isolated 24 h colonies of pure cultures of E. faecalis grown on 10% sheep blood plus Brain Heart Infusion (BHI) agar plates were suspended in sterile 0.85% NaCl solution. The cell suspension was adjusted spectrophotometrically to match the turbidity of a McFarland 0.5 scale. One mL of each tested substance was placed on the bottom of wells of 24-well cell culture plates (Corning, NY), including the control group (sterile saline). Six wells were used for each time period and irrigant concentration. Two mL of the bacterial suspension were ultrasonically mixed for 10 s with the irrigants and placed in contact with them for 10, 30, and 45 s; 1, 3, 5, 10, 20, and 30 min; and 1 and 2 h. After each period of time, 1 mL from each well was transferred to tubes containing 2 mL of freshly prepared BHI + neutralizers in order to prevent a residual action of the irrigants. All tubes were incubated at 37°C for 7 days. The tubes considered to have positive growth were those which presented medium turbidity during the incubation period. Data were analysed statistically by the Kruskal,Wallis test, with the level of significance set at P < 0.05. Results All irrigants were effective in killing E. faecalis, but at different times. Chlorhexidine in the liquid form at all concentrations tested (0.2%, 1% and 2%) and NaOCl (5.25%) were the most effective irrigants. However, the time required by 0.2% chlorhexidine liquid and 2% chlorhexidine gel to promote negative cultures was only 30 s and 1 min, respectively. Conclusions Even though all tested irrigants possessed antibacterial activity, the time required to eliminate E. faecalis depended on the concentration and type of irrigant used. [source] High salt diets dose-dependently promote gastric chemical carcinogenesis in Helicobacter pylori -infected Mongolian gerbils associated with a shift in mucin production from glandular to surface mucous cellsINTERNATIONAL JOURNAL OF CANCER, Issue 7 2006Sosuke Kato Abstract Intake of salt and salty food is known as a risk factor for gastric carcinogenesis. To examine the dose-dependence and the mechanisms underlying enhancing effects, Mongolian gerbils were treated with N -methyl- N -nitrosourea (MNU), Helicobacter pylori and food containing various concentrations of salt, and were sacrificed after 50 weeks. Among gerbils treated with MNU and H. pylori, the incidences of glandular stomach cancers were 15% in the normal diet group and 33%, 36% and 63% in the 2.5%, 5% and 10% NaCl diet groups, showing dose-dependent increase (p < 0.01). Intermittent intragastric injection of saturated NaCl solution, in contrast, did not promote gastric carcinogenesis. In gerbils infected with H. pylori, a high salt diet was associated with elevation of anti- H. pylori antibody titers, serum gastrin levels and inflammatory cell infiltration in a dose-dependent fashion. Ten percent NaCl diet upregulated the amount of surface mucous cell mucin (p < 0.05), suitable for H. pylori colonization, despite no increment of MUC5AC mRNA, while H. pylori infection itself had an opposing effect, stimulating transcription of MUC6 and increasing the amount of gland mucous cell mucin (GMCM). High salt diet, in turn, decreased the amount of GMCM, which acts against H. pylori infection. In conclusion, the present study demonstrated dose-dependent enhancing effects of salt in gastric chemical carcinogenesis in H. pylori -infected Mongolian gerbils associated with alteration of the mucous microenvironment. Reduction of salt intake could thus be one of the most important chemopreventive methods for human gastric carcinogenesis. © 2006 Wiley-Liss, Inc. [source] Long-term evolution of the acute tubular necrosis (ATN) induced by glycerol: role of myofibroblasts and macrophagesINTERNATIONAL JOURNAL OF EXPERIMENTAL PATHOLOGY, Issue 4 2002Telma J. Soares Summary. Late structural changes such as interstitial fibrosis in the renal cortex and tubular atrophy have been detected after severe acute tubular necrosis (ATN). The aim of this study was to investigate the expression of fibronectin, ,-smooth muscle actin and macrophages during the evolution of the ATN induced by glycerol and their relationship with the late structural changes observed in the kidneys of these animals. Forty-nine male Wistar rats were injected with a 50% glycerol solution, 8 mL/kg (4 mL/kg applied i.m. to each hind leg) and 14 with 0.15 m NaCl solution. Before glycerol injection on day 1, water was removed for 17 h. Blood and urine samples were collected 1 day after the injection to quantify sodium and creatinine. The animals were killed 5, 30 and 60 days after the injections and the kidneys removed for histological and immunohistochemical studies. The results of the histological and immunohistochemical studies were scored according to the extent of lesion or staining in the cortical tubulointerstitium, respectively. The percentage of tubulointerstitial lesions was determined by morphometry. Glycerol-injected rats presented a transitory increase in plasma creatinine levels and in fractional sodium excretion. The immunohistochemical studies showed increased fibronectin, ,-smooth muscle actin (,-SM-actin), TGF-, and ED-1 (macrophages) staining in the renal cortex from rats killed 5, 30 and 60 days after glycerol injection (P < 0.05) compared to control. The animals killed on day 30 and 60 also presented chronic lesions (fibrosis, tubular dilatation and atrophy) in the renal cortex, despite the recovery of renal function. Macrophages, TGF-, and myofibroblasts may have contributed to the development of renal fibrosis in these rats. [source] The hydrophilic, foaming and emulsifying properties of casein concentrates produced by various methodsINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 6 2006Janesca A. Roman Summary The hydrophilic and surfactant properties of casein concentrates made by different processes such as isoelectric precipitation and neutralization (commercial casein, CC) coagulation by rennet (casein clots, COC) and microfiltration/diafiltration (casein micelles, CM) were studied. Water absorption capacity (WAC), water solubility (WS) and water-holding capacity (WHC) were highest for CM and lowest for COC. Solubility was higher in water and in pH 5.5, 0.10 m NaCl solution for both CM and COC. Foaming capacity was better for CM than for CC at pH 4.0 and for CC at pH 6.0 and 8.0. Foam stability was low for both CM and CC at pH 4.0 but it was high for CM at pH 6.0 and 8.0 and for CC in the absence of salt. Emulsifying capacity was higher for CC at pH 4.0 and 7.0. Stability of emulsion was high for CC at pH 4.0 and for CM at pH 7.0. [source] An effective iodide formulation for killing Bacillus and Geobacillus spores over a wide temperature rangeJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2004N. Kida Abstract Aims:, To develop a sporicidal reagent which shows potent activity against bacterial spores not only at ambient temperatures but also at low temperatures. Methods and Results:, Suspension tests on spores of Bacillus and Geobacillus were conducted with the reagent based on a previously reported agent (N. Kida, Y. Mochizuki and F. Taguchi, Microbiology and Immunology 2003; 47: 279,283). The modified reagent (tentatively designated as the KMT reagent) was composed of 50 mmol l,1 EDTA-2Na, 50 mmol l,1 ferric chloride hexahydrate (FeCl3·6H2O), 50 mmol l,1 potassium iodide (KI) and 50% ethanol in 0·85% NaCl solution at pH 0·3. The KMT reagent showed significant sporicidal activity against three species of Bacillus and Geobacillus spores over a wide range of temperature. The KMT reagent had many practical advantages, i.e. activity was much less affected by organic substances than was sodium hypochlorite, it did not generate any harmful gas and it was stable for a long period at ambient temperatures. The mechanism(s) of sporicidal activity of the KMT reagent was considered to be based on active iodine species penetrating the spores with enhanced permeability of the spore cortex by a synergistic effect of acid, ethanol and generated active oxygen. Conclusions:, The data suggest that the KMT reagent shows potent sporicidal activity over a wide range temperatures and possesses many advantages for practical applications. Significance and Impact of the Study:, The results indicate development of a highly applicable sporicidal reagent against Bacillus and Geobacillus spores. [source] Preparation and characteristic of electric stimuli responsive hydrogel composed of polyvinyl alcohol/poly (sodium maleate- co -sodium acrylate)JOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008Yi Gao Abstract Maleic anhydride was used to preparare polyvinyl alcohol/poly (sodium maleate- co -sodium acrylate) hydrogels (PVA/poly(SMA-SAA)) by a repeated frost-defrost process because of its higher charge density and potential electric stimuli sensitivity. The bending angle was measured in a noncontact electric field using carbon as plate electrodes. It was found that the bending angle was dependent on various factors, including composition of hydrogel, concentration of NaCl solution, types of electrolyte solution, and electric voltage. It exhibited that the bending angle increased when the concentration of NaCl solutions and the electric voltages increased. An abnormal bending direction was observed, and it was affected not only by the kinds of hydrogels, but also by the exterior variations. The hydrogel showed good reversibility in on-off electric field and could be a candidate for practical application. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Synthesis and properties of carboxymethyl cellulose- graft -poly(acrylic acid- co -acrylamide) as a novel cellulose-based superabsorbentJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007Aili Suo Abstract A new cellulose-based superabsorbent polymer, carboxymethyl cellulose- graft -poly(acrylic acid- co -acrylamide), was prepared by the free-radical grafting solution polymerization of acrylic acid (AA) and acrylamide (AM) monomers onto carboxymethyl cellulose (CMC) in the presence of N,N,-methylenebisacrylamide as a crosslinker with a redox couple of potassium persulfate and sodium metabisulfite as an initiator. The influences of reaction variables such as the initiator content, crosslinker content, bath temperature, molar ratio of AA to AM, and weight ratio of the monomers to CMC on the water absorbency of the carboxymethylcellulose- graft -poly(acrylic acid- co -acrylamide) copolymer were investigated. The copolymer's structures were characterized with Fourier transform infrared spectroscopy. The optimum reaction conditions were obtained as follows: the bath temperature was 50°C; the molar ratio of AA to AM was 3 : 1; the mass ratio of the monomers to CMC was 4 : 1; and the weight percentages of the crosslinker and initiator with respect to the monomers were 0.75 and 1%, respectively. The maximum water absorbency of the optimized product was 920 g/g for distilled water and 85 g/g for a 0.9 wt % aqueous NaCl solution. In addition, the superabsorbent possessed good water retention and salt resistance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1382,1388, 2007 [source] Comparative corrosion performance of black oxide, sandblasted, and fine-drawn nitinol wires in potentiodynamic and potentiostatic tests: Effects of chemical etching and electropolishingJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2004Svetlana Shabalovskaya Abstract The corrosion performance of sandblasted (SB) and smooth fine-drawn (FD) medical-use nitinol wires was compared with the performance of wires with black oxide (BO) formed in air during their manufacture. Potentiodynamic and ASTM F746 potentiostatic tests in a 0.9 % NaCl solution were conducted on wires in their as-received, chemically etched, aged in boiling water, and electropolished states. As-received wires with various surface finishes revealed breakdown potentials in the range from ,100 mV to +500 mV; similar passive current density, 10,6 A/cm2; and a wide hysteresis on the reverse scan, demonstrating strong susceptibility to localized corrosion. Chemically etched wires with original black oxide displayed consistent corrosion performance and surpassed, in corrosion resistance, electropolished wires that showed significantly lower breakdown (400,700 mV) and localized corrosion potentials (,,50 to +113 mV). Sandblasted and fine-drawn wires exhibited rather inconsistent corrosion behavior. In potentiodynamic tests these wires could perform with equal probability either on the level of pretreated BO wires or rather similar to as-received wires. Both SB and FD wires revealed low breakdown potentials in the PS regime. SEM analysis performed before tests indicated that sandblasting was not efficient for the complete removal of the original scaling, and fine drawing aggravated the situation, resulting in a persistent scaling that contributed to the inferior corrosion performance. Inclusions (oxides, carbides, and oxidized carbides) inherited from the bulk and retained on electropolished surfaces are the cause of their inferior performance compared to chemically etched surfaces. In electropolished wires corrosion was initiated around inclusions. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 69B: 223,231, 2004 [source] Ammonia exchange on clinoptilolite from mineral deposits located in MexicoJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2004Roberto Leyva-Ramos Abstract This work investigated the ion exchange of ammonia on clinoptilolite obtained from mineral deposits located in San Luis Potosi and Sonora, Mexico. Experimental ion exchange isotherm data were obtained in a batch adsorber. The effects of temperature and solution pH on the ion exchange capacity were studied and it was found that the exchange capacity was slightly increased by augmenting the temperature and by decreasing the pH from 6 to 3. The ion exchange capacity was independent of the diameter of the zeolite particles. The reversibility of ion exchange was analyzed by desorbing the ammonia exchanged on the zeolite. The ion exchange was reversible when 1% NaCl solution was used as the desorbing solution, but more ammonia was desorbed using 1% KCl solution in the desorption step. It was concluded that a considerable amount of ammonia was exchanged on the clinoptilolite and that the exchange capacity was slightly dependent on the temperature and pH. Copyright © 2004 Society of Chemical Industry [source] CHARACTERIZATION AND COMPARISON OF COLLAGENS EXTRACTED FROM THE DIGESTIVE TRACT AND SKIN OF A JAPANESE AMBERJACK SERIOLA QUINQUERADIATAJOURNAL OF FOOD BIOCHEMISTRY, Issue 6 2009MAKI NISHIMOTO ABSTRACT Collagen was extracted from the digestive tract and skin of a Japanese amberjack (Seriola quinqueradiata) by acid extraction and limited pepsin digestion. The amounts of collagen solubilized from the digestive tract were smaller than those from the skin. Based on the solubility in NaCl solution, electrophoretic and peptide map patterns, and amino acid composition, the main digestive tract collagen was identified as type I, having characteristics different from those of the body wall collagen in cyclostome intestine. Further, the degree of hydroxylation of prolyl and lysyl residues in the type I collagen of the digestive tract is significantly higher than that of the skin. Collagen preparations from the digestive tract have a higher ratio of type V collagen than those from the skin. Hence, the digestive tract collagen differs from that in the skin in the degree or property of intermolecular crosslinking, posttranslational modification, and molecular species composition. PRACTICAL APPLICATIONS Partial hydrolyzate of gelatin, in other word collagen peptide, has gained popularity as a food ingredient, as it has been suggested to have health benefits, such as improvement of skin and joint conditions. Recently, attention toward collagen derived from marine origin such as fish skin increased because of the outbreak of bovine spongiform encephalopathy. Large amounts of the digestive tract, stomach, intestine and adhesion tissues are generated by fishery industries and most of them are by-products of low value. Although these organs are also rich in collagen, the collagen in fish digestive tract has not been characterized. The present study demonstrates that the collagen in digestive tract differs from the skin collagen in the solubility, posttranslational modification and molecular species composition. These facts suggest that modified collagen peptides might be obtained from the digestive tract. [source] Effect of ion-exchange fiber structure on the binding and release of model salicylatesJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 8 2005Kaisa R. Hänninen Abstract Salicylates were used as model anions to evaluate the effect of the structure (framework and ion-exchange groups) of fibrous anion-exchangers on the extent and mechanism(s) of compound binding and release. Binding was affected by the physicochemical properties of both the salicylates and the ion-exchange fibers. The highest molar amount of binding was obtained with the most lipophilic salicylate (5-chlorosalicylic acid) and the weak base (vinylpyridine) anion-exchange fibers. However, when the ion-exchange capacity was taken into account, higher binding was obtained in fibers of poly(ethylene) framework compared to the viscose-based fibers. The extent of salicylate release into NaCl solution(s) was dependent on the physicochemical characteristics of both the fiber and the bound model salicylate as well as on the amount of extracting ions. With strong base fibers (trimethylammonium), the viscose framework released the salicylates more efficiently than the poly(ethylene) framework. In the case of weak base fibers, the poly(ethylene) framework released the salicylates to a higher extent than the viscose framework. Calculated equilibrium constants (K) of the ion-exchange reactions illustrated that in addition to electrostatic interactions (pure ion-exchange mechanism), non-electrostatic interactions (hydrophobic interactions and/or hydrogen bonding) were also involved. However, the release of the salicylates was efficiently modified by the amount of extracting electrolyte, demonstrating that ion-exchange was the prevalent release mechanism. © 2005 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 94:1772,1781, 2005 [source] Combined Effect of Salt Water and High-Temperature Exposure on the Strength Retention of NextelÔ720 Fibers and NextelÔ720-Aluminosilicate CompositesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2006Triplicane A. Parthasarathy The relative contribution of fiber strength loss to reported degradation in the mechanical behavior of NextelÔ720-aluminosilicate composites after exposure to salt fog (ASTM B117) was explored. Single filament tension tests were performed on NextelÔ720 (3M, Inc., Minneapolis, MN) fibers after immersion in NaCl solutions followed by high-temperature exposure in air. The results were compared with the behavior of control specimens which received high-temperature exposure but were not immersed in NaCl solution. There was no degradation in fiber strengths for NaCl solutions below 1 wt%. However, significant degradation was observed at 5 wt% NaCl upon exposure to temperatures between 900° and 1150°C, while no degradation was observed upon an exposure to 1200°C. The relative contribution of fiber strength loss to composite degradation was estimated as nearly 50%, indicating that both fibers and matrix/interface degrade from exposure to salt water. X-ray diffraction and transmission electron microscopy of the exposed fibers and composites were conducted to help rationalize the observations. Microstructure of degraded fibers showed presence of Na at grain boundaries near the surface, without any evidence of a crystalline phase, indicating weakening from segregation or formation of an amorphous phase. The degraded composites showed that matrix and fiber/matrix interfaces had Na rich regions/phases. [source] The effects of pentoxifylline on liver regeneration after portal vein ligation in ratsLIVER INTERNATIONAL, Issue 2 2007Uzer Kucuktulu Abstract Aim: To determine the effects of pentoxifylline, a methyl xanthine derivative on hepatic cell production of uninterferred lobe after portal vein branch ligation. Methods: Sixty-six rats were randomly allocated into 9 groups with 8 rats in PVL groups and 6 rats in sham operation groups. The portal branches of the median and the lateral liver lobes, corresponding to approximately 70% of the liver voluma were ligated in the PVL groups. The control group received 0.9% NaCl solution. The rats in the treatment groups received pentoxypilline at the dose of 50 mg/kg/dy. After 1,2,4 days of portal vein ligation in both PVL and PVNL lobes the levels of adenine nucleotides were determined and flowcytometric analysis of cell cycles were performed. Results: On the first day of portal branch ligation energy charge was significantly lower, in pentoxifylline treated group comparing to pentoxfylline untreated group, both in PVL and PVNL lobes (P<0.05). Proliferative indexes were 0.38 and 0.29 in pentoxifylline treated and pentoxifylline untreated PVNL lobes respectively (P<0.05). Conclusion: Pentoxifylline treatment resulted in an increase of percentage of calls entering mitosis phase on the first day after PVL, somehow accelerating the regenaration process. [source] Kinetics of Demixing and Remixing Transitions in Aqueous Solutions of Poly(N -isopropylacrylamide): A Temperature-Jump 1H NMR StudyMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 21 2006Pavel V. Yushmanov Abstract Summary: The time course of the coil-to-globule collapse and intermolecular aggregation of poly(N -isopropylacrylamide) in aqueous solution upon exceeding the lower critical solution temperature (LCST) are investigated by temperature-jump 1H NMR spectroscopy. After the temperature jump, we record the time dependences of (i) the mobile fraction of the polymer chain as revealed by the intensity of the liquid-like NMR signal, (ii) the local mobility of those chains as revealed by the transverse relaxation time T2, and (iii) their self-diffusion coefficient D. The same data are also reported at their temperature-dependent long-time limits. The results suggest a sudden, faster than one second, collapse and intermolecular aggregation into globules and a slower reorganization/redistribution of the individual chains among and within the globular and mobile states. We found that all molecular changes are reversible if the temperature remains less than ca. 6,8 K above the LCST for less than a few minutes; under those conditions, experiments upon sudden temperature quench below the LCST show that the aggregates disintegrate and swell into coils in less than a few seconds. 1H NMR signal intensity of the methyl groups of 1 wt.-% PNIPAM dissolved in 0.1 M NaCl solution in D2O in a temperature-jump experiment from 300 to 312 K. The data were recorded by the 90°,,,(180°,2, -)n -detection of the CPMG pulse sequence. [source] Effects of Hf content and immersion time on electrochemical behavior of biomedical Ti-22Nb- xHf alloys in 0.9% NaCl solutionMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 5 2009B. L. Wang Abstract The aim of this study was to investigate the effects of Hf content and immersion time on the electrochemical corrosion behavior of the Ti-22Nb- xHf (x,=,0, 2, 4, and 6 at%) alloy samples in 0.9% NaCl solution at 37,°C and neutral pH range, utilizing the potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. From the polarization curves, all these alloys exhibited typical passive behavior, which was indicated by a wide passive region without the breakdown of the passive films and low corrosion current densities. In addition, the values of the corrosion current densities and passive current densities decreased with increase in the Hf content. The EIS results, fitted by RS(QPRP) model, exhibited capacitive behavior (high corrosion resistance) with phase angles closed to ,80° and high impedance values at low and medium frequencies, indicating the formation of a highly stable film on these alloys in the test solution. The resistance of the passive films improved with increase in the Hf content and immersion time. All these observations suggested a more noble electrochemical behavior of the Ti-22Nb- xHf alloys compared to the Ti-Nb binary alloy. [source] A comparative study on the corrosion behavior of NdFeB magnets in different electrolyte solutionsMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 10 2008Y. W. Song Abstract Sintered NdFeB magnets possess excellent magnetic properties. However, the corrosion resistance property of NdFeB is very poor due to its multiphase microstructure consisting of matrix phase Nd2Fe14B, Nd-rich phase, and B-rich phase. The corrosion behavior of NdFeB magnets in sodium hydroxide (NaOH), sodium chloride (NaCl), nitric acid (HNO3), and oxalic acid (H2C2O4) solutions was investigated by immersion and electrochemical tests. HNO3is the strongest corrosive electrolyte compared with the other three solutions. The increase in HNO3concentration can accelerate the corrosion of NdFeB magnets. NaCl belongs to medium corrosion electrolyte. A NaCl concentration of 0.5 M shows the severest corrosive feature in comparison with other concentrations of NaCl solution. NdFeB hardly suffers corrosion in NaOH and H2C2O4solutions owing to the formation of passivation films on the surface of magnets. Based on the corrosion behavior of NdFeB in different electrolytes, the possible corrosion mechanisms are discussed. [source] Electrochemical and mechanical behaviour of Sn-2.5Ag-0.5Cu and Sn-48Bi-2Zn soldersMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 8 2008G. Montesperelli Abstract In this paper, two tin-based alloys (Sn-2.5Ag-0.5Cu and Sn-48Bi-2Zn) are proposed as new lead-free solders. Alloys have been developed by melting pure elements. Samples have been evaluated in terms of microstructure, corrosion resistance and mechanical features. Corrosion tests have been performed in 3% NaCl solution by polarization curves and electrochemical impedance spectroscopy (EIS). SEM observations and EDS analysis were carried out on samples before and after corrosion tests. Static monotonic tensile tests have been performed on three specimens for each alloy. SEM and EDS analysis revealed the presence of Sn-Ag and Sn-Cu intermetallic compounds within the Sn-Ag-Cu alloy. As a result of corrosion test, the Sn-Ag-Cu alloy showed a better corrosion resistance with respect to Sn-Bi-Zn. Both alloys evidenced good mechanical properties higher than the traditional Sn-Pb system. Sn-Ag-Cu seems to be a suitable soldering material. [source] The effect of ionic peneration on semiconducting behaviour of temporarily protective oil coating on the surface of AISI 304 stainless steelMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 9 2005Q. Zhong Abstract In this paper, the semiconducting behaviour of temporarily protective oil coatings on the surface of naked and prepassivated AISI 304 stainless steel immersed in 3% aqueous NaCl solution was studied by utilizing potential-capacitance methode, Mott-Schottky analysis and impedance analysis. It was pointed out that the temporarily protective oil coating behaves as a semiconductor during its degradation. The ionic penetration and the substrate greatly affect the conduction behaviour of the oil coating. On the surface of naked AISI 304 stainless steel, the oil coating behaves as a n-type semiconductor. With increasing immersion time, the donor density of the space charge layer in the temporarily protective oil coating increases from 1019 to 1025 m,3. However, on the surface of the prepassivated substrate the space charge layer in the oil coating is significantly affected by the oxide on the steel electrode. In this case immersion time does not influence the density of charge carriers in the oil coating (1021 m,3). Impedance analysis also verify above results. [source] Simulation of galvanic corrosion of magnesium coupled to a steel fastener in NaCl solutionMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 7 2005J. X. Jia Abstract The galvanic corrosion of magnesium alloy AZ91D coupled to a steel fastener was studied using a boundary element method (BEM) model and experimental measurements. The BEM model used the measured polarization curves as boundary conditions. The experimental program involved measuring the total corrosion rate as a function of distance from the interface of the magnesium in the form of a sheet containing a mild steel circular insert (5 to 30 mm in diameter). The measured total corrosion rate was interpreted as due to galvanic corrosion plus self corrosion. For a typical case, the self corrosion was estimated typically to be , 230 mm/y for an area surrounding the interface and to a distance of about 1 cm from the interface. Scanning Kelvin Probe Force Microscopy (SKPFM) revealed microgalvanic cells with potential differences of approximately 100 mV across the AZ91D surface. These microgalvanic cells may influence the relative contributions of galvanic and self corrosion to the total corrosion of AZ91D. [source] Corrosion fatigue of spot-welded austenitic stainless steels in 3.5% NaCl solutionMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 12 2004M. E. Somervuori Abstract Corrosion fatigue and fatigue properties of spot-welded austenitic stainless steels EN 1.4301 and EN 1.4318 in 2B or 2F and 2H conditions were investigated in 3.5% sodium chloride (NaCl) solution and in air. The shear-loaded specimens were single spot overlap joints. The effect of steel grade, load, frequency, temperature and type of chloride on fatigue strength of the 1.0 mm thick steel specimens was evaluated by using the Taguchi Method®. Increase of the load, rise of temperature and lowering of the frequency accelerate corrosion fatigue of the spot-welded steel samples. Type of chloride had only a minor effect on fatigue strength. The 2B grade spot-welded steel samples exhibited better fatigue strength than the 2H grade samples of the same steels. On the basis of the results obtained by the Taguchi Method® the S-N curves were defined for the spot-welded 1.9 mm thick steels in 3.5% sodium chloride solution at 50°C. For reference the fatigue experiments were performed in air at the ambient temperature. Comparison of the results shows that corrosive environment decreases remarkably the fatigue strength of the spot-welded steels. The EN 1.4301 2H and EN 1.4318 2H steels have no distinctive difference in their corrosion fatigue strength even though they show a different fatigue behaviour in air. The microscopic investigations indicate that the fatigue cracks in the spot welds initiate from either side of the recrystallised area in the HAZ outside the spot-weld nugget both in air and in the corrosive environments. Pre-exposure in the corrosive environment seems to have no major influence on the crack initiation, because the cracks do not initiate at the heat-tinted area of the crevice where the crevice corrosion occurs. [source] Anion effects on the stress corrosion cracking behaviour of aluminium alloysMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 3 2003R. Braun Spannungsrisskorrosion; Aluminiumlegierungen; Chloride; halogenfreie Anionen Abstract The stress corrosion cracking behaviour of plate material of the aluminium alloys 2024-T351, 8090-T8171, 7475-T651, and 7075-T7351 was investigated performing constant load tests. Short transverse tensile specimens were permanently immersed in aerated aqueous 0.6 M Na2Cl solutions with additions of Na2SO4, NaNO3, NaHCO3, NH4HCO3, Na2HPO4, Na2SO3 or Na2CO3. The concentration of the added salts was 0.06 M. The applied stress was 100 MPa, except with 7075-T7351 specimens, which were loaded at 300 MPa. Environment induced failure was not observed in neutral 0.6 M NaCl solution. The various salts added promoted intergranular stress corrosion cracking with the alloys 2024-T351, 8090-T8171, and 7475-T651. Threshold stresses were generally below 100 MPa. For 8090-T8171 exposed to chloride containing electrolytes with additions of sulfate, hydrogen phosphate, or sulfite, threshold stresses were approximately 100 MPa or higher. Similar results were obtained for 7475-T651 plate when immersed in chloride-hydrogen phosphate and chloride-carbonate solutions. Alloy 7075-T7351 was resistant against intergranular stress corrosion cracking. Specimens suffered pitting corrosion during immersion in the corrosive environments. Failure observed with 7075-T7351, in particular when exposed to the chloride-nitrate solution, was associated with reduction of cross-sectional area due to pitting and transgranular stress corrosion cracking. Anioneneinflüsse auf das Spannungsrisskorrosionsverhalten von Aluminiumlegierungen Das Spannungsrisskorrosionsverhalten von Plattenmaterial der Aluminiumlegierungen 2024-T351, 8090-T8171, 7475-T651 und 7075-T7351 wurde in kurzer Querrichtung untersucht. Dauertauchversuche wurden unter konstanter Belastung in wässrigen 0,6 M NaCl Lösungen mit 0,06 M Zusätzen von Na2SO4, NaNO3, NaHCO3, NH4HCO3, Na2HPO4, Na2SO3 oder Na2CO3 durchgeführt. Die aufgebrachte Spannung betrug 100 MPa, außer bei Zugproben der Legierung 7075-T7351, die mit 300 MPa belastet wurden. Während bei Auslagerung in neutraler Natriumchlorid-Lösung kein Versagen beobachtet wurde, lösten die zugegebenen Salze bei den Legierungen 2024-T351, 8090-T8171 und 7475-T651 interkristalline Spannungsrisskorrosion aus. Die kritischen Grenzspannungen lagen überwiegend unter 100 MPa. Bei Auslagerung in chloridhaltigen Elektrolyten mit beigegebenen Sulfat-, Hydrogenphosphat- oder Sulfitionen waren die kritischen Grenzspannungen für die Legierung 8090-T8171 etwas höher; sie hatten einen um 100 MPa oder darüber liegenden Wert. Gleiches galt für die Legierung 7475-T651 in chloridhaltigen Lösungen mit Hydrogenphosphat- oder Carbonatzusätzen. Plattenmaterial der Legierung 7075-T7351 war in den untersuchten Elektrolyten beständig gegen interkristalline Spannungsrisskorrosion. Die Proben wurden jedoch durch Lochkorrosion geschädigt. Querschnittsverminderung infolge Lochkorrosion und transkristalliner Spannungsrisskorrosion führten zum Versagen von Zugproben der Legierung 7075-T7351 innerhalb der maximalen Prüfdauer von 30 Tagen, insbesondere bei Auslagerung in eine chlorid-nitrathaltige Lösung. [source] The influences of macrosegregation, intermetallic particles, and dendritic spacing on the electrochemical behavior of hypoeutectic Al-Cu alloysMICROSCOPY RESEARCH AND TECHNIQUE, Issue 11 2007Wislei R. Osório Abstract The purpose of this research is (1) to investigate the influence of Al2Cu intermetallic particles associated with the dendritic arm spacing on the corrosion resistance of different hypoeutectic Al-Cu alloys and (2) to evaluate the electrochemical behavior of a hypoeutectic Al-Cu alloy directionally solidified under unsteady-state heat flow. The as-cast samples were produced using vacuum arc remelting and vertical upward water-cooled solidification. Microscopic examinations were carried out with optical microscopy and scanning electron microscopy + energy dispersiveX-ray analyses. To evaluate the surface corrosion behavior of such alloys, all corrosion tests were performed in a 0.5-M NaCl solution at 25°C using an electrochemical impedance spectroscopy technique and potentiodynamic polarization curve analysis. Based on the tests, corrosion rate and impedance parameters were obtained. The present research has underlined the use of appropriate techniques of characterization for determining Al2Cu distribution, morphology, and fraction within the typical microstructures of Al-Cu alloys. The experimental results have established correlations between the Al-rich phase dendritic arm size, the intermetallic particles distribution in the eutectic mixture, the macrosegregation profile, and the resulting corrosion resistance. Microsc. Res. Tech., 2007. © 2007 Wiley-Liss, Inc. [source] Microhardness and Corrosion Behavior of Ni-SiC Electrodeposited CoatingsPLASMA PROCESSES AND POLYMERS, Issue S1 2007Hachemi Ben Temam Abstract Composite coatings suitable for protection against corrosion were prepared by electrodeposition of chloride-nickel coating containing silicon carbide particles maintained in the suspension. The Ni-SiC composite coatings showed a better corrosion resistance in 0.6 M NaCl solution and high hardness than nickel, electrodeposited under the same conditions. The coatings deposited were uniform and adherent to the substrates. X-Ray diffraction (XRD) studies showed that the nickel coatings grow with (111) preferred orientation. [source] | ||||||||||||||||||||||