Showing papers on "Distilled water published in 2002"

Removal of Antibiotics from Surface and Distilled Water in Conventional Water Treatment Processes

Abstract: Conventional drinking water treatment processes were evaluated under typical water treatment plant conditions to determine their effectiveness in the removal of seven common antibiotics: carbadox, sulfachlorpyridazine, sulfadimethoxine, sulfamerazine, sul- famethazine, sulfathiazole, and trimethoprim. Experiments were conducted using synthetic solutions prepared by spiking both distilled/ deionized water and Missouri River water with the studied compounds. Sorption on Calgon WPH powdered activated carbon, reverse osmosis, and oxidation with chlorine and ozone under typical plant conditions were all shown to be effective in removing the studied antibiotics. Conversely, coagulation/flocculation/sedimentation with alum and iron salts, excess lime/soda ash softening, ultraviolet irra- diation at disinfection dosages, and ion exchange were all relatively ineffective methods of antibiotic removal. This study shows that the studied antibiotics could be effectively removed using processes already in use in many water treatment plants. Additional work is needed on by-product formation and the removal of other classes of antibiotics.

Effect of different artificial aging conditions on ceramic-composite bond strength.

Abstract: Purpose The purpose of this study was to evaluate the influence of different storage conditions on the bond strength of adhesive bonding systems to yttria-partially stabilized zirconia ceramic. Materials and methods Acrylic glass tubes filled with composite resin were bonded to ceramic disks. After sandblasting and ultrasonic cleansing of the ceramic samples, they were bonded using five bonding methods. Samples were tested for tensile bond strength following five different storage conditions: 3 days in distilled water at 37 degrees C, 31 days in distilled water at 37 degrees C, 37,500 thermocycles between 5 and 55 degrees C within 31 days, 150 days in distilled water at 37 degrees C, and 150 days in distilled water with 37,500 thermocycles performed at intervals. Results Mean resin bond strength values ranged from 7.7 to 41.9 MPa. There were statistically significant differences among groups, as revealed by the Kruskal-Wallis test. Some storage conditions influenced the resin bond strength statistically significantly, as revealed by the Wilcoxon rank sum test modified by Bonferroni-Holm. Conclusion Thermocycling had a much higher impact on the durability of the resin bond strength to zirconia ceramic than did water storage at a constant temperature.

Evaluation of photocatalytic disinfection of crude water for drinking-water production

Abstract: TiO2-photocatalysis disinfection experiments were carried out with both E. coli in distilled water and natural water samples from the Cauca River (Cali, Colombia). The experiments performed with E. coli in distilled water showed no increase in cell concentration after the treated solution was left in the dark for 24 h. However, the experiments carried out with natural water samples showed drastic culturable cell concentration increase 24 h after stopping the irradiation. This shows the lack of residual effect of TiO2-photocatalysis.

Influence of organic solvents on the performance of polymeric nanofiltration membranes

Abstract: Separations in organic solvents are a new field of application for nanofiltration. Only a few polymeric nanofiltration membranes are commercially available for these separations, the major problem being the limited chemical stability in organic solvents. This article studies the influence of different organic solvents (methylene chloride, acetone, hexane, ethyl acetate, and ethanol), their performance on the four nanofiltration membranes (N30F, NF-PES-10, MPF 44, and MPF 50) specified to be compatible with the solvents used. The pure water flux (distilled water) of these membranes and the rejection of maltose were measured before and after 10 days of exposure to one of the above-mentioned solvents. The results show that not all of the membranes are compatible with the solvents used, and that the membrane performance shifts towards lower rejections for the hydrophilic membranes (N30F, NF-PES-10, and MPF 44) and towards higher pure water fluxes for the hydrophobic membrane (MPF 50). The water flux is not si...

In Vitro Fungicidal Activity of Acidic Electrolyzed Oxidizing Water

Abstract: Acidic electrolyzed oxidizing (EO) water, generated by electrolysis of a dilute salt solution, recently gained attention in the food industry as a nonthermal method for microbial inactivation. Our objective was to determine if EO water has potential to control foliar diseases in greenhouses. Test fungi suspended in distilled water were combined with EO water (1:9 water:EO water) for various time periods, the EO water was neutralized, and germination was assessed after 24 h. Germination of all 22 fungal species tested was significantly reduced or prevented by EO water. All relatively thin-walled species (e.g., Botrytis, Monilinia) were killed by incubation times of 30 s or less. Thicker-walled, pigmented fungi (e.g., Curvularia, Helminthosporium) required 2 min or longer for germination to be reduced significantly. Dilution of EO water with tap water at ratios of 1:4 and 1:9 (EO:tap water) decreased efficacy against Botrytis cinerea. The presence of Triton X-100 (all concentrations) and Tween 20 (1 and 10%) eliminated the activity of EO water against B. cinerea. EO water did not damage geranium leaf tissue and inhibited lesion development by B. cinerea when applied up to 24 h postinoculation. EO water has a wide fungicidal activity which could facilitate its use as a contact fungicide on aerial plant surfaces and for general sanitation in the greenhouse.

Intermediate free radicals in the oxidation of wastewaters

Abstract: The cleaning action on wastewater as obtained through oxidation methods has been investigated by means of EPR spectroscopy to achieve qualitative and quantitative information on the radicals produced upon utilising peracetic acid and hydrogen peroxide with and without UV irradiation. The DEPMPO spin trap was employed to detect hydroxyl and carbon-centred short living radicals during water disinfection, either in the absence or in the presence of UV-C irradiation. Moreover, three different kinds of water (wastewater, demineralized water, distilled water) were analysed in order to assess the contribution of Fenton reactions to the radical production. The spectroscopic results are discussed in relation to the efficiency of the different oxidising agents and UV irradiation in wastewater disinfection evaluated as Escherichia coli, faecal and total coliforms inactivation.

Effects of cyclic temperature changes on water sorption and solubility of composite restoratives.

Abstract: This study investigated the effects of cyclic temperature changes on the water sorption and solubility of four commercial composite resins (Silux Plus, Z100, Ariston pHc and Surefil). The methodology was based upon ISO 4049 procedures with modifications for specimen dimension and thermal-cycling. Eighteen disc specimens (10 +/- 1 mm diameter and 1 +/- 0.1 mm thick) were made for each composite and randomly divided into three groups. The specimens were stored in a desiccator maintained at 35 +/- 1 degrees C until a constant mass was achieved and treated as follows: Group 1--stored in distilled water at 356 degrees C for 178 hrs; Group 2--stored in distilled water at 35 degrees C for 173 hours and subjected to five hours of thermal-cycling with an upper temperature of 45 degrees C; and Group 3--stored in distilled water at 35 degrees C for 173 hours and subjected to five hours of thermal-cycling with an upper temperature of 60 degrees C. Mass after treatment was measured and specimens were re-conditioned to constant mass. The volume of the specimens was obtained and water sorption/solubility calculated. Data was analyzed using factorial ANOVA/Scheffe's post-hoc test at significance level 0.05. The effects of thermal-cycling on water sorption was material dependent. Thermal-cycling at an upper temperature of 60 degrees C significantly increased water sorption of Silux Plus. A significant increase in water sorption was also observed when Z100 was thermal-cycled at an upper temperature of 45 degrees C. The water sorption of Ariston pHc and Surefil was not affected by thermal-cycling. Thermal-cycling did not affect the solubility of all composites. For all treatment groups, Surefil had significantly lower water sorption than the other composites evaluated. The water sorption of Z100 and Surefil was significantly lower than Silux Plus and Ariston pHc.

Characteristic moisture curves and maximum water content of two crop residues

Abstract: Limited data are available relating water potential (Ψ) to crop residue water content (Θ), although this relationship is important to study decomposition and moisture retention of the residue layer in no-till systems and other agricultural situations where residues are used. The objectives of this study were (i) to determine the characteristic moisture curves of rye (Secale cereale L.) and clover residues (Trifolium incarnatum L.), and (ii) to determine residue characteristics that can predict maximum water content of crop residues. Air-dried residues were separated into leaves and stems, cut into 0.5 cm length pieces and saturated with distilled water. Pieces of the drained residues were dried to various water contents in the laboratory and then transferred into thermocouple psychrometer chambers. Characteristic moisture functions of the type Ψ = a ċ Θ−b, where a and b are empirical constants, were fitted to the data. The characteristic moisture curves had a similar shape to that of a Cecil sandy loam soil used as an example; however, while plant residues were able to retain up to 4.3 g H2O g−1, the mineral soil retained only 0.22 g H2O g−1. Soluble carbohydrate concentration can be used as a practical index to estimate maximum water content of residues, given the good relationship between both variables (R2 = 0.92).

Fluoride release from model glass ionomer cements.

Abstract: Glass ionomer cements (GICs) are an important class of biomedical material used extensively for color matched mercury free, dental restorations. GICs can release clinically beneficial amounts of fluoride and have acceptable handling properties which make them suitable as dental restoratives. The fluoride release of model GICs produced from specially synthesized fluoro-alumino-silicate glasses was studied. Nine glasses of varying fluoride content based on 4.5SiO2–3Al2O3–1.5P2O5–(5–Z)CaO–ZCaF2 were synthesized and cement disks were prepared from them. The glass transition temperature reduced with increasing fluorine content of the glass. Fluoride ion release was measured into distilled water as a function of time for up to 140 days using a fluoride ion selective electrode. The quantity of fluoride released was found to be proportional to the fluorine content of the glass at all intervals time. The cumulative fluoride release was proportional to square root time. Substituting strontium for calcium in the glass had little influence on the fluoride release behavior of the cements.

Reducing bacterial counts in dental unit waterlines: distilled water vs. antimicrobial agents.

Abstract: Background This study evaluated five chemical disinfectants to compare their abilities to improve dental unit waterline quality and assess their effects, if any, on the biofilm layer Methods Sixty new dental units, with a closed-circuit water system, were used to compare microbial levels in DUWLs treated with five antimicrobials: Listerine, Bio 2000, Rembrandt, Dentosept, and sodium fluoride to a control group of sterile distilled water alone over a six-week period For all units, the waterlines were filled with solution, left overnight, and then flushed for 30 seconds with sterile distilled water the following morning prior to patient treatment Waterlines were examined for biofilm buildup using scanning electron microscopy and colony-forming-unit counts Results The sodium fluoride and the four chemical antimicrobials reduced the microbial count to 200 cfu/ml or less Only samples taken from dental units receiving the control treatment (distilled water with no added antimicrobial) failed to meet ADA's stated goal Examination of the SEMs revealed an apparent decrease in the biofilm mass but not elimination, despite repeated treatment with the four antimicrobial materials Conclusions Even in a closed-circuit water system, distilled water alone cannot reduce microbial contamination of dental treatment water from dental unit waterlines to the 200 cfu/ml ADA stated goal However, water treated with Listerine mouthrinse, Rembrandt mouthrinse, Bio 2000, 05 percent sodium fluoride and Dentosept, did meet the microbial reduction goal The biofilm apparently was reduced in volume, but not entirely eliminated Clinical significance The ADA goal of a maximum of 200 cfu/ml was achieved using any of five chemical antimicrobials and distilled water in a closed-water system Despite the successful reduction in microbial contamination of the dental treatment water, the biofilm was not completely eliminated Biofilm elimination and prevention would be needed through some other means

Water quality has a pronounced effect on cholesterol-induced accumulation of Alzheimer amyloid beta (Abeta) in rabbit brain

Abstract: Increased circulating cholesterol is known to promote risk of coronary artery disease. It is now emerging that cholesterol promotes production and accumulation of amyloid beta (Abeta) deposited in the hallmark pathologic lesion of Alzheimer's disease (AD), the senile plaque, perhaps by shifting away from normal metabolism of amyloid beta protein precursor (AbetaPP) to beta. Previous studies employing the cholesterol-fed rabbit model of AD demonstrated that induction of AD-like Abeta accumulation in brain could be reversed by co-administration of cholesterol lowering drugs or removing cholesterol, prompted initiation of an AD Cholesterol-Lowering (Statin) Treatment Trial. We now present data that identify a previously unrecognized role for dietary water quality on the severity of neuropathology induced by elevated cholesterol. Neuronal accumulation of Abeta induced by increased circulating concentrations of cholesterol in the New Zealand white rabbit is attenuated when distilled drinking water is administered compared to use of tap water. The numbers of neurons in cholesterol-fed rabbits that exhibited Abeta immunoreactivity, relative to normal chow-fed controls, increased approximately 2.5 fold among animals on tap water but only approximately 1.9 fold among animals on distilled water. This yielded a statistically significant approximately 28% reduction due to the use of distilled water. In addition, the subjectively assessed intensity of neuronal Abeta immunoreactivity was consistently reduced among cholesterol-fed rabbits allowed distilled drinking water compared to cholesterol-fed rabbits on tap water. As intensity of antibody immunoreactivity is likely related to concentration of antigen, the identified difference among cholesterol-fed rabbits allowed distilled drinking water may hold greater importance than a significant reduction in numbers of affected neurons. The effect on neuronal Abeta immunoreactivity intensity was observable among cholesterol-fed rabbits reared and allowed tap water when performing studies in three distinct locales. Pilot data suggest the possibility of increased clearance of Abeta from the brain, identified as increased blood levels, among cholesterol-fed rabbits administered distilled water compared to animals on tap water. The agent(s) occurring in tap water, excluded by distillation, promoting accumulation of neuronal Abeta immunoreactivity is(are) yet undisclosed, but arsenic, manganese, aluminum, zinc, mercury, iron and nitrate have tentatively been excluded because they were not identifiable (below detection limits) in the tap water of the three locales where the cholesterol-induced neuropathologic difference was observable. These findings suggest that water quality may impact on human health in the setting of increased circulating cholesterol levels, and could illustrate a truly simple life-style change that could be of benefit in AD.

Hygrothermal Effects on RT-Cured Glass-Epoxy Composites in Immersion Environments. Part A: Moisture Absorption Characteristics

Abstract: A study on the effect of moisture absorption characteristics of RT-cure glass/epoxy composite and epoxy casting specimens immersed in freshly prepared artifi- cial seawater and distilled water maintained at 333o K are presented in this paper. Results showed that the equilibrium moisture absorption value and the diffusion rate (slope of the moisture absorption curve) are higher in specimens immersed in distilled water than those of artificial seawater. The mixture rule for moisture absorption estimates has been verified for specimens immersed in both environments. These theoretically calculated values com- pared well with those experimentally obtained. The time of saturation for specimens immersed in seawater was found to be higher than that for those immersed in distilled water.

The use of water soluble polymers for the pre-concentration and separation of copper, lead, and chromium prior to their determination by graphite furnace atomic absorption spectrometry

Abstract: In this study, a water-soluble polymer, polyacrylamide containing R-(+)-Cysteine end groups was used for the separation and preconcentration of copper, lead and chromium prior to their analysis by graphite furnace atomic absorption spectrometry. The sample and polymer solution were mixed and metal-bound polymer was precipitated upon addition of acetone. The precipitate was separated from solution and dissolved directly with distilled water. By this way, analyte elements were again transferred into the liquid phase and analyzed by graphite furnace atomic absorption spectrometry. The advantages and disadvantages of the method compared to those of the traditional batch and column techniques using water insoluble solid materials were described in all aspects. The method is simpler and faster compared to other preconcentration and separation techniques. Recoveries from matrix free aqueous solutions are higher than 96% and relative standard deviations were lower than ±3%.

Apparent activation energy of fused silica optical fibers in static fatigue in aqueous environments

Abstract: Static fatigue of fused silica optical fiber is known to be caused by stress assisted reaction of silica with ambient moisture. Past studies have often been conducted in hot water to accelerate experiments compared with cooler vapor environment. However, changes in the pH of water with temperature has an important influence on the fatigue rate, but has been ignored in the literature. To study the effect of pH, static fatigue of fused silica fibers has been characterized over a range of temperatures in both distilled water and pH 7 buffer solution. The apparent activation energies were then obtained for the different environments. The silica fibers were found to fatigue faster in pH 7 buffer solution than in distilled water, and the apparent activation energy for fatigue was higher in pH 7 buffer. The difference in the results for the two environments can be understood in terms of the difference in their pH and how the pH varies with temperature.

Crystallization of anatase from amorphous titania in hot water and in vitro biomineralization

Abstract: Anatase of good crystallinity has been developed on titanium substrates by soaking in a 30 mass% hydrogen peroxide solution at 80°C for 8h, soaking in distilled water at ambient temperature for 12h, and subsequently aging in distilled water at 80°C for 3d. The anatase layers exhibit good bioactivity as inducing apatite deposition in Kokubo's simulated body fluid within 2d.

Chloride cell responses to long‐term exposure to distilled and hard water in the gill of the armored catfish, Hypostomus tietensis (Loricariidae)

Abstract: The morphological changes in the gill chloride cells of the armored catfish, Hypostomus tietensis, were investigated after 15 days’ exposure to either distilled or hard water. The thickness of the water–blood barrier in the lamellae increased significantly in fish kept in distilled water due to the high proliferation of chloride cells. The apical surface of about 68% of chloride cells was sharply reduced by the development of an apical crypt with a sponge-like surface, although no change in the chloride cell fractional area was found. In contrast, H. tietensis kept in Na+, Cl− and Ca2+ rich water displayed no significant changes in the number of chloride cells or in their apical surface morphology compared with the control fish. Chloride cell response to ion challenge in H. tietensis suggested the involvement of different strategies to maintain homeostasis in ion-poor water, which may be related to the life history of species.

Reducing bacterial counts in dental unit waterlines: tap water versus distilled water.

Abstract: Background The maximum recommended level of microbial contamination of water from dental unit waterlines (DUWL) is 200 colony-forming units per milliliter (CFU/mL). This article addresses the importance of water selection in achieving that standard. Methods Microbial contamination in water samples from 75 new dental units, with a closed-circuit water system, were compared using combinations of tap water and sterile distilled water with and without two chemical disinfectants (bleach and 0.12% chlorhexidine gluconate, Bio2000) over a six-week period. Baseline tap water samples were collected and tested initially. Results The microbial plate counts of seven tap water specimens (controls) ranged from 4 to 95 CFU/mL. These results were well below both the 500 CFU/mL standard for public drinking water and the 200 CFU/mL goal for dental treatment water. However, when passed through dental units, no significant bacterial reduction was achieved for samples of tap water (Group 1), tap water treated with bleach (Group 2), or tap water treated with Bio2000 (Group 4). Only water samples from dental units using Bio2000 alone (Group 3) or a combination of sterile, distilled water with Bio2000 (Group 5) met or exceeded the 200 CFU/mL standard. Conclusions Using tap water alone or tap water with bleach did not improve water quality. However, the American Dental Association (ADA) standard for reduced microbial contamination of dental unit waterlines was met using Bio2000 and distilled water treated with Bio2000. Clinical significance The ADA standard of 200 CFU/mL was achieved using a closed water system and distilled water treated with Bio2000. Using 100% Bio2000 is also effective, but more costly.

Effect of Anaerobiosis on Filter Media Pollutant Retention

Abstract: This paper presents the results of experiments conducted to determine if four potential filter media (sand, activated carbon, peat moss, and compost) could retain previously-trapped pollutants even under anaerobic conditions. The results indicated that permanent retention of heavy metals may occur even in an anaerobic environment. However, retention of nutrients may not occur under these conditions. RESEARCH BACKGROUND AND DESCRIPTION One of the primary problems with downflow filtration of stormwater runoff is the clogging of the filter prior to the medium’s exhaustion of the chemical capacity. Upflow filtration using a siphon control may improve the life of the filters. However, for upflow filtration with siphon control for entering water, it would be expected that only the top of the filter would be exposed to air (unlike a gravity filter where the top and bottom are potentially exposed to air between storms), and an anaerobic environment could develop. The purpose of this series of tests was to determine if filter media were able to retain trapped pollutants even if the filter developed an anaerobic environment, either throughout the filter or only in sections of the filter, between storm events. A full description of the tests and results can be found in Clark (2000). For this set of tests, four media were used: activated carbon, peat moss, compost, and sand. These media were selected because they provided the best overall results during the preliminary work – with sand being used as a comparison to traditional filter material. The media were exposed to a concentrated solution – spiked tap water (10 mg/L of lead, copper, zinc, iron, nitrate, phosphate, and ammonia) – for several hours. The water was then filtered through a 0.45-μm membrane filter. The amount of material sorbed onto the media was calculated using the preand post-sorption water concentrations (a blank sample was evaluated in a similar manner, except with no media, so that the effects of sorption onto the exposure containers would be accounted for in the data analysis). After rinsing with a buffered distilled water to remove any loosely bound material and to replace any concentrated pore water, the media were exposed to pre-settled stormwater runoff (from Star Lake, a stormwater detention pond, in Hoover, Alabama) for a period of several weeks. One sample of each medium was maintained in an aerobic environment where aeration stones were used to keep the lake water saturated in oxygen. The other sample of each medium was exposed to the Star Lake water while in sealed BOD bottles, where the naturally-occurring matter/organisms in the water would consume the oxygen and create an anaerobic environment. No seeding was done to encourage more rapid development of anaerobic conditions. At the end of the exposure time, the dissolved oxygen (DO) concentration and the oxidation-reduction potential (ORP) of each aerobic and anaerobic sample were taken. Then the samples were filtered through a 0.45-μm gel membrane filter, and the filtrates were analyzed for the ammonia, nitrate, total nitrogen, phosphate, total phosphorus, and the following metals (calcium, magnesium, iron, copper, lead and zinc.