Iodate and iodo-trihalomethane formation during chlorination of iodide-containing waters: role of bromide

The kinetics of iodate formation is a critical factor in mitigation of the formation of potentially toxic and off flavor causing iodoorganic compounds during chlorination. This study demonstrates that the formation of bromine through the oxidation of bromide by chlorine significantly enhances the oxidation of iodide to iodate in a bromide-catalyzed process. The pH-dependent kinetics revealed species specific rate constants of k(HOBr + IO(-)) = 1.9 × 10(6) M(-1) s(-1), k(BrO(-) + IO(-)) = 1.8 × 10(3) M(-1) s(-1), and k(HOBr + HOI) < 1 M(-1) s(-1). The kinetics and the yield of iodate formation in natural waters depend mainly on the naturally occurring bromide and the type and concentration of dissolved organic matter (DOM). The process of free chlorine exposure followed by ammonia addition revealed that the formation of iodo-trihalomethanes (I-THMs), especially iodoform, was greatly reduced by an increase of free chlorine exposure and an increase of the Br(-)/I(-) ratio. In water from the Great Southern River (with a bromide concentration of 200 μg/L), the relative I-incorporation in I-THMs decreased from 18 to 2% when the free chlorine contact time was increased from 2 to 20 min (chlorine dose of 1 mg Cl(2)/L). This observation is inversely correlated with the conversion of iodide to iodate, which increased from 10 to nearly 90%. Increasing bromide concentration also increased the conversion of iodide to iodate: from 45 to nearly 90% with a bromide concentration of 40 and 200 μg/L, respectively, and a prechlorination time of 20 min, while the I-incorporation in I-THMs decreased from 10 to 2%.     

Microstructure and Crystallography of Titanium Nitride Whiskers Grown by a Vapor–Liquid–Solid Process

Titanium nitride whiskers having diameters of 0.5 to 1.5 μm and aspect ratios in the range of 20 to 50 have been produced by a new commercially scalable vapor–liquid–solid process. Electron microscopy studies have shown that most of the whiskers can be classified into two types based upon structure and morphology. The whiskers of one type are single crystals and have a growth direction of (100). Whiskers of the second type are comprised of two crystals having a common (110) growth direction. Both types have smooth surfaces and relatively few internal defects. Additionally, a small percentage of whiskers have considerable internal structure related to significant magnesium impurities.     

Pipe lining abrasion testing for paste backfill operations

Pipe wear in paste backfill mining operations represents a great cost to mining companies. The replacement of prematurely worn pipes results in the shut down of the entire paste system. Abrasion testing performed on various pipe lining samples yielded both quantitative and qualitative data. Both standard and non-standard methods were explored during testing. The pipe materials are ranked by their relative wear resistance as well as energy per unit mass loss. The latter may allow for better prediction of pipe wear, this in turn could prove worthwhile when scheduling maintenance downtime for such a system where cost savings would be beneficial.     

CART algorithm for spatial data: Application to environmental and ecological data

Most statistical learning techniques such as Classification And Regression Trees (CART) assume independent samples to compute classification rules. This assumption is very practical for estimating quantities involved in the algorithm and for assessing asymptotic properties of estimators. In many environmental or ecological applications, the data under study are a sample of some regionalized variables, which can be modeled as random fields with spatial dependence. When the sampling scheme is very irregular, a direct application of supervised classification algorithms leads to biased discriminant rules due, for example, to the possible oversampling of some areas. The CART algorithm is adapted to the case of spatially dependent samples, focusing on environmental and ecological applications. Two approaches are considered. The first one takes into account the irregularity of the sampling by weighting the data according to their spatial pattern using two existing methods based on Voronoï tessellation and regular grid, and one original method based on kriging. The second one uses spatial estimates of the quantities involved in the construction of the discriminant rule at each step of the algorithm. These methods are tested on simulations and on a classical dataset to highlight their advantages and drawbacks. They are then applied on an ecological data set to explore the relationship between pollen data and presence/absence of tree species, which is an important question for climate reconstruction based on paleoecological data.     

Timothy silage with low dietary cation-anion difference fed to nonlactating cows

Decreasing the dietary cation-anion difference (DCAD) by using anion sources before calving reduces hypocalcemia in cows at calving. Reduced DCAD from CaCl₂-fertilized timothy hay achieves similar results, but the effects of feeding low-DCAD forage as silage have not been determined. The objective of this study was to evaluate the effect of low-DCAD timothy silage on dry cows. Six nonlactating and nonpregnant Holstein cows were used in a replicated 3 × 3 Latin square. Treatments were 1) control diet (DCAD = 232 mEq/kg of dry matter, DM); 2) low-DCAD diet using a low-DCAD timothy silage (LDTS; DCAD = −21 mEq/kg of DM); and 3) low-DCAD diet using a fermentation by-product (LDBP; DCAD = −32 mEq/kg of DM). Differences between dietary treatments were considered statistically significant at P ≤ 0.05 and tendencies were noted when 0.05 < P < 0.10. Compared with the control, feeding LDTS tended to decrease DM intake (10.6 vs. 12.5 kg/d) and decreased urinary pH (6.15 vs. 8.18) as well as apparent digestibility of DM (67 vs. 69%). Blood pH (7.37 vs. 7.42), HCO₃⁻ (25.3 vs. 27.5 mM), and base excess (0.4 vs. 3.1 mM) were decreased, and blood Cl⁻ (29.6 vs. 29.1 mg/dL) was increased. Apparently absorbed Na and Cl were higher and apparently absorbed K, P, and digested ADF were lower for LDTS compared with the control. Both LDTS and LDBP resulted in similar DM intake. Urinary pH tended to be higher (6.15 vs. 5.98) and percentage of digested DM was lower (67 vs. 70%) with LDTS compared with LDBP. Blood ionized Ca (5.3 vs. 5.4 mg/dL) tended to be lower and blood Cl⁻ (29.6 vs. 30.1 mg/dL) was lower, whereas blood pH (7.37 vs. 7.33), HCO₃⁻ (25.3 vs. 21.5 mM), and base excess (0.4 vs. −3.8 mM) were higher with LDTS compared with LDBP. Apparent absorption of Na, Cl, S, and P, as well as apparent digestion of acid detergent fiber, neutral detergent fiber, and N were lower, and K, Cl, S, P, Mg, and N were less retained with LDTS compared with LDBP. Results confirm that low-DCAD timothy silage can be used to produce a compensated metabolic acidosis by decreasing the DCAD of rations served to nonlactating dairy cows.     

Reduction by (-)-cicletanine of the vascular reactivity to angiotensin II in rats

Cicletanine [particularly the levorotatory (-)enantiomer] inhibits calcium/calmodulin cyclic GMP phosphodiesterase (PDE) in vascular smooth muscle (VSM) and potentiates the vasorelaxant actions of the guanylate cyclase activators sodium nitroprusside (SNP) and atriopeptin II, but the possible interference with vasopressor mechanisms remains to be determined. We tested racemic (+/-) cicletanine for its ability to modify the vascular responses to vasocontractant agents in pithed rats. The most significant results were obtained with angiotensin II (AII). Therefore, the dose of AII that increased the carotid artery blood pressure (BP) 50 mm Hg was twice as high in cicletanine-pretreated (50 mg/kg orally, p.o.) as that in vehicle-pretreated animals (ED50 = 0.48 +/- 0.012 vs. 0.25 +/- 0.007 microgram/kg, p < 0.05). The displacement by cicletanine represented 47.2% of that obtained with losartan (40 micrograms/kg, intravenously, i.v.). Similar results were obtained with (-)-cicletanine (p.o. or i.v.), but not with (+)-cicletanine. In isolated rat aorta, the contraction induced by AII was reduced by (-)-cicletanine in a noncompetitive manner (the percent reduction was independent of the AII concentration). (-)-Cicletanine reduces the vascular reactivity to AII, which plays a key role in several forms of hypertension. These findings are compatible with an action of (-)-cicletanine at any of the numerous steps that couple the occupation of AII receptors to the final contractile response, such as calcium/calmodulin cyclic GMP PDE.     

Male-produced Aggregation Pheromone of Colopterus truncatus: Structure, Electrophysiological, and Behavioral Activity

A male-produced aggregation pheromone was demonstrated in Colopterus truncatus Randall (Coleoptera: Nitidulidae) by gas chromatographic comparisons of male and female volatile emissions. Male-specific compounds were identified with coupled gas chromatographic–mass spectrometric (GC-MS) analysis and GC and MS comparison of authentic standards. Physiological activity was evaluated by coupled gas chromatographic–electroantennographic (GC-EAG) recordings, and electroantennographic (EAG) assays of standards. The male-produced volatiles eliciting responses from male and female antennae (and relative abundance) were (2E,4E,6E)-3,5-dimethyl2,4,6-octatriene (1) (1.8), (2E,4E,6E)-4,6-dimethyl-2,4,6-nonatriene (2) (100), and (2E,4E,6E,8E)-3,5,7-trimethyl-2,4,6,8-decatetraene (3) (3.3). A fourth male-specific compound, (2E,4E,6E,8E)-4,6,8-trimethyl-2,4,6,8-undecatetraene (4) (0.6) was not EAG-active. EAG dose–response studies showed that the antennae were most sensitive to 2 followed by 3 and 1. Synthetic 2, binary blends of 1 and 3, and tertiary blends of 1, 2, and 3 were highly attractive in the field when synergized with fermenting whole-wheat bread dough. In the field, cross-attraction to the C. truncatus pheromone components was observed for Carpophilus lugubris Murray, C. antiquus Melsheimer, and C. brachypterus Say.     

Simulation of coupled heat and moisture transfer in air-conditioned buildings

The simultaneous heat and moisture transfer in the building envelope has an important influence on the indoor environment and the overall performance of buildings. In this paper, a model for predicting whole building heat and moisture transfer was presented. Both heat and moisture transfer in the building envelope and indoor air were simultaneously considered; their interactions were modeled. The coupled model takes into account most of the main hygrothermal effects in buildings. The coupled system model was implemented in MATLAB-Simulink, and validated by using a series of published testing tools. The new program was applied to investigate the moisture transfer effect on indoor air humidity and building energy consumption under different climates. The results show that the use of more detailed simulation routines can result in improvements to the building's design for energy optimisation through the choice of proper hygroscopic materials, which would not be indicated by simpler calculation techniques.