An Efficient Probe for Rapid Detection of Cyanide in Water at Parts per Billion Levels and Naked-Eye Detection of Endogenous Cyanide

A new molecular probe based on an oxidized bis-indolyl skeleton has been developed for rapid and sensitive visual detection of cyanide ions in water and also for the detection of endogenously bound cyanide. The probe allows the naked-eye detection of cyanide ions in water with a visual color change from red to yellow ((max)=80nm) with the immediate addition of the probe. It shows high selectivity towards the cyanide ion without any interference from other anions. The detection of cyanide by the probe is ratiometric, thus making the detection quantitative. A Michael-type addition reaction of the probe with the cyanide ion takes place during this chemodosimetric process. In water, the detection limit was found to be at the parts per million level, which improved drastically when a neutral micellar medium was employed, and it showed a parts-per-billion-level detection, which is even 25-fold lower than the permitted limits of cyanide in water. The probe could also efficiently detect the endogenously bound cyanide in cassava (a staple food) with a clear visual color change without requiring any sample pretreatment and/or any special reaction conditions such as pH or temperature. Thus the probe could serve as a practical naked-eye probe for in-field experiments without requiring any sophisticated instruments.

Exclusive Detection of Sub-Nanomolar Levels of Palladium(II) in Water: An Excellent Probe for Multiple Applications

A new colorimetric probe has been developed for the detection and estimation of Pd-II at sub-nanomolar concentrations. The probe consisted of rhodamine (signaling unit), which was linked with a bis-picolyl moiety (binding site) through a phenyl ring. Pd-II induced opening of the spirolactam ring of the probe with the generation of a prominent pink color. The excellent selectivity of the probe towards Pd-II over Pd-0 or Rh-II ensured its potential utility for the detection of residual palladium contamination in pharma-ceutical drugs and in Pd-catalyzed reactions. The probe showed a ``turn-on'' (bright yellow) fluorescence upon the addition of Pd-II, which made it suitable for the detection of Pd contaminants in mammalian cells.

Formulation, processing and water stability of pelleted feeds with varying levels of protein used in carp nutrition studies

Four dry pelleted feeds containing 20%, 30%, 40% and 45% protein were formulated incorporating casein as the main source of protein for use in carp nutrition studies. The caloric content in all the feeds was maintained constant. The method of processing is described. The formulated diets were tested for water stability. This test has revealed that the diet containing 20%, 30% and 40% protein had better stability than that containing 45% protein. This was due to the relatively higher fat content in the former three diets. However, all the feeds were sufficiently stable at the end of one hour in which time carps are known to utilise supplementary diets.

Interactions of dietary levels of protein and energy on rainbow trout (Oncorhynchus mykiss) in desert brackish water

A 3x3 factorial experiment was conducted to determine the optimum protein to energy (P/E) ratio for rainbow trout in brackish water. Three crud protein levels and three energy levels at each protein level were utilized. Diets were made in semi-purified that in all of them fish meal, casein and gelatin as the sources of protein and dextrin, starch and oil as the sources of energy were used. Each of experimental diets was fed to triplicate groups of 20 fish with an average individual weight of 81.5 g in 9 2000-1 flow trough fiberglass tanks. During this experiment water temperature, dissolved oxygen, PH and EC were 15±2°C, 6.5-8.1 mg/1, 7.7-8.6 and 25400 grills respectively. The diets were fed at a rate between 1.6-2 wet body weight% per day depended to water temperature in three equal rations and adjusted two weekly for 84 days. At each of protein levels, weight gain percent (%WG), average daily growth percent (%ADG), protein efficiency ratio (PER), apparent net protein utilization percent (%ANPU), or percent of protein deposited, specific growth rate (SGR) and condition factor (CF) were found to increase and food conversion ratio (FCR) was found to decrease with an increasing energy levels from 370 to 430 Kcal/100g. Fish fed a 35% protein, 430 Kcal/100g energy diet with a P/E ratio of 81.4 mg protein/ Kcal PFV energy, attained the best growth performance. Fat and moisture of carcass were affected by protein and energy levels of test diets while protein and ash of carcass were relatively constant in different treatments.

The distribution and concentration levels of trace metals in water and sediments of Lake Victoria, Kenya

The water and bottom sediments of Lake Victoria (Kenya) were analysed for A1, Fe, Mn, Zn, Pb, Cu, Cr and Cd. The total metal concentrations were determined and their mean variations and distributions discussed. The bottom lake waters showed higher concentration levels than the surface waters. The range of values (in mg/l) in the bottom and surface lake waters were as follows: Surface Waters: A1(0.08 - 3.98), Fe(0.09 - 4.01), Mn(0.02 - 0.10). Zn(0.01 -0.07), Pb(0.001- 0.007), Cu(not detected - 0.006), Cr(not detected - 0.004). Bottom Waters: A1(0.1 0 - 6.59), Fe(0.23 - 9.64), Mn(0.04 - 0.39), Zn(0.01- 0.08), Pb(0.002 - 0.009), Cu(not detected - 0.03). Cr(not detected -0.002). River mouths and shallow areas in the lake showed higher total metal concentrations than offshore deeper areas. Apart from natural metal levels, varied urban activities and wastes greatly contribute to the lake metal pollution as shown by high Pb and Zn levels in sediments, around Kisumu and Homa Bay areas. Other comparatively high values and variations could be attributed to the varied geological characteristics of the lake and its sediments. Compared to the established W.H.O (1984) drinking water standards manganese, aluminium and iron levels were above these limits whereas zinc, lead, chromium, copper and cadmium were below.

Modelling the effect of water immersion thermal processing on polyacetylene levels and instrumental colour of carrot disks

C₁₇ polyacetylenes are a group of bioactive compounds present in carrots which have recently gained scientific attention due to their cytotoxicity against cancer cells. In common with many bioactive compounds, their levels may be influenced by thermal processes, such as boiling or water immersion. This study investigated the effect of a number of water immersion time/temperature combinations on concentrations of these compounds and attempted to model the changes. Carrot samples were thermally treated by heating in water at temperatures from 50–100 °C and holding times of 2–60 min. Following heating, levels of falcarinol (FaOH), falcarindiol (FaDOH), falcarindiol-3-acetate (FaDOAc) and Hunter colour parameters (L^*, a^*, b^*) were determined. FaOH, FaDOH, FaDOAc levels were significantly reduced at lower temperatures (50–60 °C). In contrast, samples heated at temperatures from 70–100 °C exhibited higher levels of polyacetylenes (p < 0.05) than did raw unprocessed samples. Regression modelling was used to model the effects of temperature and holding time on the levels of the variables measured. Temperature treatment and holding time were found to significantly affect the polyacetylene content of carrot disks. Predicted models were found to be significant (p < 0.05) with high coefficients of determination (R²).

Inorganic arsenic levels in rice milk exceed EU and US drinking water standards

Under EU legislation, total arsenic levels in drinking water should not exceed 10 microg l(-1), while in the US this figure is set at 10 microg l(-1) inorganic arsenic. All rice milk samples analysed in a supermarket survey (n = 19) would fail the EU limit with up to 3 times this concentration recorded, while out of the subset that had arsenic species determined (n = 15), 80% had inorganic arsenic levels above 10 microg l(-1), with the remaining 3 samples approaching this value. It is a point for discussion whether rice milk is seen as a water substitute or as a food, there are no EU or US food standards highlighting the disparity between water and food regulations in this respect.

Noise levels and hearing conservation in a water treatment facility

This paper describes a study assessing the sound levels and noise exposures of a municipal water treatment plant to determine the level of employee noise exposure dosages and to make any necessary recommendations regarding reducing the risk of noise induced hearing loss in employees.

Vibrational energy levels of water

Several quartic force fields and a full sextic anharmonic force field for H,O have been determined from high-quality ab initio calculations, the highest at the aug-cc-pVQZ CCSD(T) level of theory. These force fields have been used to determine vibrational excited state band origins up to 15 000 cm - ’ above the zero-point level, using both a perturbation-resonancea pproach and a variational approach. An optimisedq uartic force field hasb eeno btained by least squares refinement of our best ab initio results to fit the observed overtone levels of 5 symmetrically substituted isotopomers of water (Hi60, Hi70, HisO, D,O, and T,O) with an rms error of less than 10 cm-‘, using the perturbation-resonancem odel for the vibrational calculation. Predicatel east squaresr efinement was usedt o provide a loose constraint of the refined force field to the ab initio results. The results obtained prove the viability of the perturbation-resonancem odel for usei n larger molecular systemsa nd also highlight someo f its weaknesse

Responses of freshwater biota to rising salinity levels and implications for saline water management: a review

All of the plants and animals that make up freshwater aquatic communities are affected by salinity. Many taxa possess morphological, physiological and life-history characteristics that provide some capacity for tolerance, acclimatisation or avoidance. These characteristics impart a level of resilience to freshwater communities.     To maintain biodiversity in aquatic systems it is important to manage the rate, timing, pattern, frequency and duration of increases in salinity in terms of lethal and sublethal effects, sensitive life stages, the capacity of freshwater biota to acclimatise to salinity and long-term impacts on community structure.     We have limited understanding of the impacts of saline water management on species interactions, food-web structures and how elevated salinity levels affect the integrity of communities. Little is known about the effect of salinity on complex ecosystem processes involving microbes and microalgae, or the salinity thresholds that prevent semi-aquatic and terrestrial species from using aquatic resources. Compounding effects of salinity and other stressors are also poorly understood.    Our current understanding needs to be reinterpreted in a form that is accessible and useful for water managers. Because of their complexity, many of the remaining knowledge gaps can only be addressed through a multidisciplinary approach carried out in an adaptive management framework, utilising decision-making and ecological risk assessment tools.

Urinary fluoride excretion in children exposed to fluoride toothpaste and to different water fluoride levels in a tropical area of Brazil

The aim of this study was to evaluate the urinary fluoride excretion of 2- to 7-year-old children exposed to different water fluoride concentrations in the city of Catolé do Rocha, PB, Brazil. Forty-two children were allocated to 3 groups according to the concentration of fluoride in the water: G1 (n=10; 0.5-1.0 ppm F), G2 (n=17; 1.1-1.5 ppm F) and G3 (n= 15; >1.51 ppm F). The study was carried out in two 1-week phases with 1-month interval between the moments of data collection: in the first phase, the children used a fluoride toothpaste (FT) (1,510 ppm F) for 1 week, whereas in the second phase a non-fluoride toothpaste (NFT) was used. The urine was collected in a 24-h period in each week-phase according to Marthaler's protocol. The urinary fluoride excretion data expressed as mean (SD) in ì g/24 h were: G1-FT= 452.9 (290.2); G1-NFT= 435.1 (187.0); G2-FT= 451.4 (224.0); G2-NFT= 430.3 (352.5); G3-FT=592.3 (390.5); and G3-NFT=623.6 (408.7). There was no statistically significant difference between the water fluoride groups, and regardless of the week phase (ANOVA, p>0.05). The use of fluoride toothpaste (1,510 ppmF) did not promote an increase in urinary fluoride excretion. There was a trend, though not significant, as to the increase of urine fluoride concentration in relation to fluoride concentrations in the water. The excretion values suggest that some children are under risk to develop dental fluorosis and information about the appropriate use of fluoride is necessary in this area.

Seven years of external control of fluoride levels in the public water supply in Bauru, São Paulo, Brazil

luoridation of the public water supplies is recognized as among the top ten public health achievements of the twentieth century. However, the positive aspects of this measure depend on the maintenance of fluoride concentrations within adequate levels. Objective: To report the results of seven years of external control of the fluoride (F) concentrations in the public water supply in Bauru, SP, Brazil in an attempt to verify, on the basis of risk/ benefit balance, whether the levels are appropriate. Material and Methods: From March 2004 to February 2011, 60 samples were collected every month from the 19 supply sectors of the city, totaling 4,641 samples. F concentrations in water samples were determined in duplicate, using an ion-speciflc electrode (Orion 9609) coupled to a potentiometer after buffering with TISAB II. After the analysis, the samples were classified according to the best risk-benefit adjustment. Results: Means (±standard deviation) of F concentrations ranged between 0.73±0.06 and 0.81±0.10 mg/L for the different sectors during the seven years. The individual values ranged between 0.03 and 2.63 mg/L. The percentages of the samples considered low risk for dental fluorosis development and of maximum benefit for dental caries prevention (0.55-0.84 mg F/L) in the first, second, third, fourth, fifth, sixth, and seventh years of the study were 82.0, 58.5, 37.4, 61.0, 89.9, 77.3, and 72.4%, respectively, and 69.0% for the entire period. Conclusions: Fluctuations of F levels were found in the public water supply in Bauru during the seven years of evaluation. These results suggest that external monitoring of water fluoridation by an independent assessor should be implemented in cities where there is adjusted fluoridation. This measure should be continued in order to verify that fluoride levels are suitable and, if not, to provide support for the appropriate adjustments.