Artificial Tap Water Research Articles

Element release from lead crystal ware and metallic hip flasks

The release of 21 elemental ions from lead crystal ware and metallic hip flasks into different food simulants as well as alcoholic beverages was investigated in this study. For this purpose, an ICP-MS method including a sample pre-treatment based on microwave-assisted digestion was developed and validated. Elemental ion release from lead crystal glasses into artificial tap water, 0.5% citric acid solution and white wine, respectively, was only analysed for Pb. Within 24 h, Pb release from crystal glass was shown to increase with time. To account for repeated use, at least three consecutive release experiments were performed, which showed – with one remarkable exception – constant or decreasing levels of element ion release. However, after four months resting period, Pb release from crystal glass was higher than before. In contrast, all 21 elemental ions were detected to be released from the hip flasks into 0.5% citric acid solution, apple liqueur and herb liqueur, respectively. Release of Cd, Cr, Ni, As, TI, Sn and most prominently Pb from hip flasks was in the range of and above the respective release limit (SRL) as set by the Council of Europe (CoE). When focussing on the third repetition, only one out of six hip flasks met the suggested SRL for all determined elements in all test solutions. This demonstrates both, that the SRLs of the CoE can be met and that producers of hip flasks may have to review their manufacturing processes.

Tea film formation in artificial tap water.

On the surface of tea infusions, the formation of a transparent, shiny film which cracks upon disturbance can often be observed. This study aims to determine how water composition, tea varieties, and tea additives impact the formation and properties of tea film, often also called tea scum. The strength of the surface film, composed of polyphenols complexed with various ions from tap water, was investigated by interfacial rheology. Microscopy and ellipsometry were used to investigate structure and thickness of the adsorption layer, respectively. We find that green tea forms more visible layers than black tea in soft and moderate artificial tap water, but in these same waters, black tea demonstrated greater surface strength. In hard artificial tap water, green tea demonstrated greater surface strength than black. No visible layer nor surface strengthening was observed on rooibos tea. Brews in hard artificial tap water formed brittle films for green tea, fracturing at strains one order of magnitude lower than in soft or moderate. Despite large variations in film strength, black tea at all water hardness levels tested formed a film with 20 nm thickness. In black tea an increased resilience to deformation was found when adding β-casein, a protein found in milk.

Capture and Extraction of Particulate Lead from Point-of-Use Filters

Lead (Pb) in tap water remains a threat to human health. The total lead concentration in tap water is the sum of the concentrations of dissolved and particulate lead. Prior research has described point-of-use (POU) filters as sampling devices to quantify lead in tap water; however, there are questions regarding the effectiveness of this method for particulate lead. The objective of this study was to determine the effectiveness of the extraction method for recovering particulate lead accumulated in POU filters. Four Pb(II) solids and two Pb(IV) solids were loaded onto POU filters separately and in combination. Our results showed that the POU filters effectively removed particulate lead from artificial tap water and that at least 92% of loaded lead solids could be recovered using the same flow-through extraction method developed for dissolved lead. The extraction of Pb(IV) solids was slower than the extraction of Pb(II) solids, but both could be fully extracted in 2 L of acid. Overall, this study demonstrated that POU filters can be used as sampling devices for total lead concentrations in tap water that contains appreciable particulate lead. Moreover, this sampling method has the potential to be extended to other inorganic and organic contaminants in tap water with different extractants.

Corrosion performance, corrosion fatigue behavior and mechanical integrity of an extruded Mg4Zn0.2Sn alloy

Magnesium alloys are promising as load bearing components. They are inevitably exposed to cyclic loading and corrosive environment in actual service, which can consequently result in corrosion fatigue failure and loss of mechanical integrity of the material. Therefore, in the present study, the corrosion behavior, corrosion fatigue performance and mechanical integrity of an extruded Mg4Zn0.2Sn (wt.%) alloy were thoroughly studied in two corrosive electrolytes. Strong localized corrosion occurred when the alloy was immersed in deionized water based sodium chloride (NaCl) solution. The poor corrosion resistance of the alloy resulted in a fast deterioration of the tensile properties after pre-exposure to salt spray and a poor fatigue resistance in deionized water based NaCl solution. In comparison, the active dissolution of the substrate was sufficiently suppressed in artificial tap water based NaCl solution due to the formation of highly protective corrosion product layers. This consequently conferred longer fatigue life on the alloy in the electrolyte. Our results emphasized the influence of corrosion on the fatigue behavior and tensile properties of magnesium alloys.

Effects of Salicylic Acid and Sucrose Solution on Vase Life of Cut Antigonon leptopus Inflorescences and Their Potential as Cut Flowers for Flower Arrangement

Pink Antigonon leptopus have potential to be commercialized as cut flowers for flower arrangement. In order to determine cut inflorescences' vase life, vase solution treatments containing Artificial Tap Water as control, salicyclic acid (SA) at 100, 200, 300 mg/L and combination of 100, 200, 300 mg/L SA with 2% sucrose were conducted. Parameters observed were vase life, relative fresh weight (RFW), vase solution uptake (VSU), flower drop (FD), flower colour, relative water content (RWC) and pH. The results showed that cut inflorescences in vase treatment containing 200 mg/L SA + 2% sucrose and 300 mg/L + 2% sucrose had 1.6 fold longer vase life than the control, showing higher water uptake and reduced flower drop by 28%.

Release of aluminium and thallium ions from uncoated food contact materials made of aluminium alloys into food and food simulant.

In order to investigate the release of aluminium ions from food contact materials, three different types of uncoated aluminium menu trays for single use were tested with the foodstuffs sauerkraut juice, apple sauce and tomato puree, as well as with the food simulants 5 g/L citric acid solution and artificial tap water. To mimic a consumer relevant exposure scenario, the aluminium trays were studied using time and temperature gradients according to the Cook & Chill method, also taking into account storage time at elevated temperatures during the delivery period. The release of aluminium was found to exceed the specific release limit (SRL) of 5 mg aluminium per kilogram of food specified by the Council of Europe by up to six times. Furthermore, a release of thallium was also detected unexpectedly.Kinetic studies showed a comparable behaviour in the release of aluminium, manganese and vanadium as components of the aluminium alloy itself. In contrast, thallium could be identified as a surface contaminant or impurity because of an entirely different kinetic curve. Kinetic studies also allowed activation energy calculations.Additional camping saucepans were tested as an article for repeated use. In three subsequent release experiments with citric acid (5 g/L), artificial tap water and tomato puree as benchmark foodstuffs, the results were comparable to those of the uncoated wrought alloy aluminium trays.

Antibacterial silver nanocluster/silica composite coatings on stainless steel

A coating made of silver nanocluster/silica composites has been deposited, via a radio frequency (RF) co-sputtering technique, for the first time onto stainless steel (AISI 304L) with the aim to improve its antibacterial properties. Different thermal treatments after coating deposition have been applied in order to optimize the coating adhesion, cohesion and its antibacterial properties. Its applicability has been investigated at realistic conditions in a cheese production plant.The physico-chemical characteristics of the coatings have been analyzed by means of different bulk and surface analytical techniques. Field emission scanning electron microscopy (FESEM), X-ray Photoelectron Spectroscopy (XPS), contact angle measurements and atomic force microscopy (AFM) were employed to assess coating morphology, composition, surface roughness, wetting properties, size and local distribution of the nanoparticles within the coating. Tape tests were used to determine the adhesion/cohesion properties of the coating. The amount and time-dependence of released silver in solutions of acetic acid, artificial water, artificial tap water and artificial milk were determined by means of Atomic Absorption Spectroscopy (AAS). The antibacterial effect of the coating was evaluated at different experimental conditions using a standard bacterial strain of Staphylococcus aureus in compliance with National Committee for Clinical Laboratory Standards (NCCLS) and AATCC 147 standards. The Ahearn test was performed to measure the adhesion of bacteria to the coated stainless steel surface compared with a control surface.The antibacterial coating retained its antibacterial activity after thermal treatment up to 450°C and after soaking in common cleaning products for stainless steel surfaces used for e.g. food applications. The antibacterial capacity of the coating remained at high levels for 1-5days, and showed a good capacity to reduce the adhesion of bacteria up to 30days. Only a few percent of silver in the coating was released into acetic acid, even after 10days of exposure at 40°C. Most silver (>90%) remained also in the coating even after 240h of continuous exposure. Similar observations were made after repeated exposure at 100°C. Very low levels of released silver in solution were observed in artificial milk. No release of silver nanoparticles was observed either in synthetic tap water or in artificial milk at given conditions.The coating further displayed good antibacterial properties also when tested during working conditions in a cheese production plant.

Ozone electrogeneration on Pt-TaOy sol-gel film modified titanium electrode: Effect of electrode composition on the electrocatalytic activity

This work examines the ozone electrogeneration (OE) at a binary coating of different nominal compositions (Pt)x-(TaOy)(100–x), where x (percentage in the precursor solution) varied between 1% and 100%, coated on titanium substrate prepared by a sol-gel technique. The OE is performed in an artificial tap water at room temperature (25°C). The percentages of Pt and TaOy in the coating significantly affect the electrocatalytic activity towards oxygen evolution. The oxygen evolution was retarded to a different extent based on the electrode composition. The largest retardation was obtained at the (Pt)10-(TaOy)90 electrode (ca. 480 mV positive shift) as compared with the (Pt)100-(TaOy)0 electrode. This was reflected in a high current efficiency (CE) of OE (ca. 19.3%) at the former electrode. This value is considered to be among the highest values reported for OE at 25°C in neutral media. The composite electrodes were characterized by voltammetric and surface techniques. A plausible explanation for the change of the efficiency of OE with the electrode composition is given based on the electrochemical results.

Brass corrosion in chlorinated tap water inhibited by phosphate ions

The combined effect of phosphate ions as corrosion inhibitor and sodium hypochlorite as biocide is studied on aluminum brass in contact with artificial tap water. The interaction between phosphates and hypochlorite was evaluated by electrochemical techniques for films formed between 2 and 192 h and by weight loss tests for immersion times of 90 days. Raman spectroscopy and X-ray photoelectron spectroscopy were used to study the passive layer. When the biocide agent is present, dezincification is the predominant form of localized corrosion after long time exposures. When the inhibitor is present, a nobler pitting potential was found. Electrochemical impedance spectroscopy (EIS) results suggest the development of a compact passive layer, regardless of the presence of the biocide. No localized attack was detected on samples immersed for 90 days at open circuit potential in the presence of phosphates, even when NaClO is present. Weight loss analysis showed inhibition efficiencies higher than 90 % when phosphates and the biocide are present. The oxidative nature of NaClO could favor Zn dissolution and enhance the precipitation of Zn3(PO4)2 layer, producing a more compact surface layer.

The Effect of Oral Processing on the Viscosity of Thickened Drinks for Patients With Dysphagia.

ObjectiveTo determine whether a gum-containing thickener maintains its viscosity better during oral processing than a completely starch-based thickener.MethodsThirty-five healthy volunteers participated in a double-blind, cross-over study. Artificial tap water was thickened to honey-like consistency (effective viscosity of 1,300±100 mPa·s at a shear rate of 50 per second at 20℃) with a starch-based thickener (SB) or a gum-containing thickener (GC). Bolus viscosity was determined after standardized oral processing of the thickened water by the subjects for 10 and 20 seconds. Significant effects were determined by ANOVA analysis and pairwise comparisons.ResultsBoth thickeners were susceptible to breakdown during oral processing. However, GC-thickened water retained its viscosity significantly better than SB-thickened water.ConclusionThe presence of gums has a protective effect on the starch hydrolysis by salivary amylase in thickened drinks, which may facilitate safer swallowing.

Subpopulation distribution of motile sperm relative to activation medium in steelhead (Oncorhynchus mykiss)

In the present study, steelhead sperm were activated in artificial tap water, ovarian fluid, activating saline, or in combinations of these media, and motility characteristics were determined using computer-assisted sperm analysis. Motility characteristics of individual sperm were then assessed to test the hypothesis that motile sperm are distributed among discrete subpopulations and that their distribution is influenced by the activation medium. Analysis with k-means clustering detected three discrete motile sperm subpopulations in steelhead semen, regardless of the activation medium. Based on multivariate analysis of variance, proportions of these subpopulations did not differ between sperm activated with ovarian fluid and activating saline, or any combination of these two media. However, subpopulation distributions for sperm activated with either ovarian fluid or activating saline were influenced by the level of dilution of these media in artificial tap water. There was an increase in the number of sperm in high velocity (curvilinear), high straightness, and high wobble subpopulation with increased levels of ovarian fluid or activating saline. The change in sperm motility characteristics with a change in activation medium may play a role in normal fertilization, as discharged sperm pass from seminal plasma and water through ovarian fluid en route to the egg.

Surface characterization of copper, zinc and brass in contact with tap water inhibited with phosphate ions

The composition of the surface layers has been investigated on copper, zinc and brass in contact with moderately hard, highly carbonated and chloride rich artificial tap water (ATW). Cyclic voltammetry, reflectance spectroscopy, X-ray diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy have been used to identify the changes in composition that result from the incorporation of sodium orthophosphate to ATW. The results showed that when PO43− is added, the film changes its composition and it also becomes thinner, denser and more compact. On copper, the presence of CuO in the passive film can be correlated to the improvement in the corrosion behavior in the presence of phosphate ions. In the case of brass, the development of a thinner, compact and less porous Zn3(PO4)2 layer hinders Cu(I) dissolution. A mechanism explaining the effect of this inhibitor is proposed, which accounts for the experimental results.

Phosphate ions used as green inhibitor against copper corrosion in tap water

Three dosages of PO 4 3 - ions are evaluated as corrosion inhibitors of copper in artificial tap water by measuring the corrosion potential, polarization resistance, electrochemical impedance and reflectance spectra. The water is moderately hard, highly carbonated and chloride-rich. The results show that the surface film is composed by Cu 2O. When the inhibiting agent is added, the film becomes thicker, denser and more compact. This behaviour is attributed to CuO incorporating into the passive layer. The optimal dosage of inhibitor is 10 mg l −1 P when the polarization resistance increases three times. The inhibitor retards the pit initiation, without hindering pit growth.

A comparative analysis of copper and brass surface films in contact with tap water

A study of the surface oxide films naturally grown on copper and brass in contact with drinkable water is presented. The investigation focuses on the influence of Zn as alloying element on the corrosion resistance of brass. Artificial tap water, employed as electrolyte, simulates a practical application of these materials. The surface films were grown at open circuit potential for 2 and 192 hours. Diverse in-situ techniques such as cyclic voltammetry, polarization curves, electrochemical impedance spectroscopy and UV-Vis reflectance spectroscopy were employed. Even when the surface layer is mainly composed of cuprous oxide, Zn(II) species are incorporated in the surface film grown on brass. At longer ageing times, the thickness increases, without affecting the composition of the surface films. The corrosion current was calculated for both materials using various techniques. The corrosion current density and the anodic currents in the polarization curves decreased as the ageing time increased, particularly in the case of brass. This improvement in the performance of the film on brass can be attributed to the incorporation of Zn(II) species into the surface layer, particularly as the film consolidates at longer times.

Brass dezincification in a tap water bacterial suspension

The dezincification of Al–brass under the influence of Pseudomona fluorescens in potable water is investigated. The experiments were carried out using artificial tap water, pH 7.6. For comparison, a bacterial suspension, was also used. Potentiodynamic reduction curves, polarization curves, polarization resistance and impedance spectroscopy as well as reflectance spectroscopy were used to characterise the surface films grown at open circuit potential. The dezincification associated to the presence of bacteria was revealed by changes in the reduction curves, and also by changes in the reflectance spectra. No significant differences were observed between the fitting parameters of the impedance spectra. The Tafel slopes were found to increase in the bacterial suspension. The corrosion currents are higher than in the inoculated electrolyte, particularly in the case of brass. This increment is attributed to the higher Tafel slope and is taken as an indication of the dezincification phenomenon.

Localized attack of copper and brass in tap water: the effect of Pseudomonas

The presence of Pseudomonas fluorescens in artificial tap water (ATW) affects the composition of the oxide layer and the susceptibility to pitting corrosion of copper and 70/30 brass. The surface layer was investigated by means of a combination of electrochemical and spectroelectrochemical techniques involving cyclic voltammograms, potentiodynamic reduction curves, anodic polarisation curves, weight-loss tests and reflectance spectroscopy. In the sterile conditions the mass loss is lower in brass than in copper while the presence of bacteria enhances the attack in brass. Dezincification in inoculated electrolyte was revealed by microscopic observation, as well as by potentiodynamic reduction curves. Zn dissolution was also supported by spectroscopic evidence. Slow-rate voltamperometric curves were used to determine potential values characteristic of localized corrosion. In the presence of bacteria, the pitting potential moves towards more positive values for both materials but the difference between the repassivation and the pitting potential increases. Bigger and deeper pits can be seen in the presence of microorganisms.

Endocrine effects of environmental pollution on Xenopus laevis and Rana temporaria

To determine the capacity of sewage treatment work effluents to disrupt the endocrine system under semifield conditions, two amphibian species, Xenopus laevis and Rana temporaria, were exposed to the effluent of a regional sewage treatment plant in South Bavaria during larval development until completion of metamorphosis. Exposure was carried out in river water (Würm) as a reference, and a 1:12-mixture sewage effluent representing the real situation on the spot, and in a higher concentration of sewage using a 1:2 mixture. An accidental impact of industrial wastewater into the reference and dilution medium, Würm, which was caused by a spate in the respective area during the sensitive period of sex differentiation of amphibian larvae, is assumed to be responsible for the relatively high percentage of females observed by histological analysis in all treatment groups. All of these values were higher than those determined in controls exposed to artificial tap water in laboratory experiments conducted in a comparable study design. Sex ratios between species, revealed by the semifield study with decreasing portions of females from control to 1:12 to 1:2, were strongly correlated. Determination of biomarker-mRNA-levels in Xenopus liver using semiquantitative RT-PCR at the end of the experimental phase, when exposure regime has turned into the initially expected situation with the highest load of potential estrogens in the effluent, followed by 1:2 and 1:12 mixture, resulted in a significant increase of Vitellogenin-mRNA in female juveniles exposed to the highest portion of sewage, whereas expression of both androgen and estrogen receptor-mRNA showed no clear differences. The results concerning the induction of estrogenic biomarkers are in accordance with our findings for estrogen receptor binding of sample extracts from the Würm and sewage taken in parallel at the end of the experiment, when sewage extracts possessed a much higher ability to displace [ 3H]estradiol from the estrogen receptor than the ones extracted from the mixtures.

Effects of the biological nematicide, DiTera®, on movement and sensory responses of second stage juveniles of Globodera rostochiensis, and stylet activity of G. rostochiensis and fourth stage juveniles of Ditylenchus dipsaci

AbstractDiTera® (Valent BioSciences Corp.), a novel biological nematicide obtained from fermentation with a hyphomycete fungus, adversely affected activity and movement through sand columns of second stage juveniles (J2) of Globodera rostochiensis. Electrophysiological tests demonstrated that exposure to 1% DiTera® prevented sensory perception of potato root diffusate. Electropharyngeograms of stylet protractor muscle activity showed that prior exposure of fourth stage juveniles of Ditylenchus dipsaci and J2 of G. rostochiensis to 1% DiTera® significantly reduced stylet thrusting when nematodes were transferred to artificial tap water or 10 mM serotonin, respectively. The modes of action and the control potential of this biological nematicide are discussed.

ECN-measurements at copper in artificial tap water – Investigation of anion-effects

Electrochemical noise analysis was succesfully applied to study anion effects in the first 20 h starting period of copper corrosion in tap water. The influence of chloride, sulfate and bicarbonate as single anions and the interactions between them in three anion solutions were characterized in terms of standard deviation and PSD(I) data as well as interaction coefficients obtained from the evaluation of a set of experiments designed according to a statistical 23-factorial plan. The results let conclude that sulfate has an activating and chloride a passivating effect. Bicarbonate seems to act as a buffering agent. It is obviously the combination of the presence of all three anions in a narrow range of concentration ratios which finally leads to pitting corrosion. The relevance of these results from short term exposure for the long term performance of copper in tap water and the likelihood of pitting corrosion should now be investigated in long term exposure tests. Elektrochemische Rauschmessungen an Kupfer in kunstlichem Trinkwasser – Untersuchung von Anionen-Effekten Die elektrochemische Rauschanalyse wurde erfolgreich zum Studium von Anioneneffekten in den ersten 20 h der Korrosion von Kupfer in Trinkwasser eingesetzt. Der Einflus von Chlorid, Sulfat und Bikarbonat als Einzelionen und deren Wechselwirkung untereinander wurden als Standardabweichungen und PSD(I)-Steigungen und uber Wechselwirkungskoeffizienten charakterisiert, welche durch Auswertung von Experimenten aus einem 23-Faktorenplan berechnet wurden. Aus den Resultaten geht hervor, das Sulfat einen aktivierenden und Chlorid einen passivierenden Einflus besitzt. Bikarbonat scheint als Puffersubstanz wirksam zu werden. Es ist offensichtlich die Kombination aus der Anwesenheit aller drei Anionen in einem engen Bereich von Konzentrationsverhaltnissen, welche letztlich zur Lochkorrosion fuhrt. Die Relevanz dieser Resultate aus Kurzzeitversuchen fur das Langzeitverhalten von Kupfer in Trinkwasser und die Lochkorrosionswahrscheinlichkeit sollte nunmehr durch Langzeitauslagerungsversuche uberpruft werden.

Catfish electroreceptor organ functioning during five days exposure to different calcium environments

Catfish, Ictalurus melas, were pre-adapted to artificial tap water with 1.2 mM Ca2+ for two weeks, and subsequently transferred to artificial tap water with 0.6, 1.2, or 2.2 mM Ca2+ for one week in order to investigate the effect of the environmental Ca2+-concentration on stimulus encoding and the frequency characteristics in ampullary electroreceptor organs. Within 30 minutes after transfer, the spontaneous activity of the primary afferents, as well as gain and phase of the stimulus induced responses changed transiently corresponding to the Ca2+-concentration. One day after transfer the Ca2+-induced changes of the spontaneous activity had disappeared as well as the differences between the sensitivities at frequencies of 2, 8, 12, 16 and 20 Hz in 0.6 and 1.2 mM Ca2+, whereas at 16 and 20 Hz in 2.2 mM Ca2+ the sensitivity was still elevated. The Ca2+-induced phase shift was strongly frequency dependent. At 2 Hz no Ca2+ effect on the phase was observed, whereas at 12, 16 and 20 Hz significant effects could be demonstrated up till three days after transfer. The latency was not affected by the transfer.