Formation of chloroform and chlorinated organics by free-chlorine-mediated oxidation of triclosan

The widely used antimicrobial agent triclosan (5-chloro-2-(2,4-dichlorophenoxy)phenol) readily reacts with free chlorine under drinking water treatment conditions. Overall second-order kinetics were observed, first-order in free chlorine and first-order in triclosan. Over the pH range of 4-11.5, the kinetics were pH sensitive as a result of the pH dependent speciation of both triclosan and free chlorine. Using a Marquardt-Levenberg routine, it was determined that this pH effect indicates that the dominant reaction in this system is between the ionized phenolate form of triclosan and hypochlorous acid (HOCl). The overall second-order rate coefficient was determined to be kArO- = 5.40 (+/- 1.82) x 10(3) M(-1) s(-1). Three chlorophenoxyphenols and two chlorophenols were identified by gas chromatographic-mass spectroscopic analysis. The chlorophenoxyphenol compounds include two monochlorinated triclosan derivatives (5,6-dichloro-2-(2,4-dichlorophenoy)phenol and 4,5-dichloro-2-(2,4-dichlorophenoxy)phenol) and one dichlorinated derivative (4,5,6-trichloro-(2,4-dichlorophenoxy)phenol); these species form via bimolecular electrophilic substitution of triclosan. 2,4-Dichlorophenol was detected under all reaction conditions and forms via ether cleavage of triclosan. In experiments with excess free chlorine, 2,4,6-trichlorophenol was formed via electrophilic substitution of 2,4-dichlorophenol. Chloroform formation was observed when an excess of free chlorine was present. A Hammett-type linear free-energy relationship (LFER) using Brown-Okamoto parameters (sigma+) was established to correlate the reactivity of HOCI and the phenolate forms of triclosan and other chlorophenols (log kArO- = -(10.7 +/- 2.2)Sigmasigma(+)o,m,p + 4.43). This LFER was used to obtain estimates of rate coefficients describing the reactivity of the intermediates 5,6-dichloro-2-(2,4-dichlorophenoy)phenol (kArO- approximately equal to 6 x 10(2)), 4,5-dichloro-2-(2,4-dichlorophenoxy)phenol (kArO- approximately equal to 3 x 10(2)), and 4,5,6-trichloro-(2,4-dichlorophenoxy)phenol (kArO- approximately equal to 4 x 10(1)).     

Naloxone blocks reinforcement but not motivation in an operant runway model of heroin-seeking behavior.

Examined the effects of opiate receptor antagonism on both the motivation to seek heroin and the reinforcing consequences of heroin administration. Male rats were trained to discriminate between olfactory cues predicting either the delivery of intravenous heroin reinforcement (S+) or saline (S-). Subjects were then tested in the presence of the opiate receptor antagonist, naloxone (0.5, 1.0, or 3.0 mg/kg intraperitoneally) in a straight-arm runway. Naloxone had no effect on either S+ or S- trials. However, 24 hr later on the first posttreatment trial, Ss that had received heroin in the presence of naloxone (on the previous trial) now traversed the alley more slowly when presented with the S+. These data suggest that although the motivation to seek heroin was not disrupted by naloxone, the reinforcing consequences of heroin administration were. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dichotic ear advantages in adults with Down's syndrome predict speech production errors.

Intellectually challenged adults, with and without Down's syndrome (DS), pointed to drawings of animals following the dichotic presentation of animal names. Although there were no reliable ear differences between the 2 groups, there was tremendous between-persons variability within the group of participants with DS. Moreover, left-ear advantages in persons with DS were associated with more speech production errors when participants either read or repeated a string of 1 syllable words. This was not true for control participants. The relationship between ear advantage and speech errors in persons with DS could reflect their unique pattern of cerebral specialization and brain development. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Detection of mines and minelike targets using principal componentand neural-network methods

Introduces a system for real-time detection and classification of arbitrarily scattered surface-laid mines from multispectral imagery data of a minefield. The system consists of six channels which use various neural-network structures for feature extraction, detection, and classification of targets in six different optical bands ranging from near UV to near IR. A single-layer autoassociative network trained using the recursive least square (RLS) learning rule was employed in each channel to perform feature extraction. Based upon the extracted features, two different neural-network architectures were used and their performance was compared against the standard maximum likelihood (ML) classification scheme. The outputs of the detector/classifier network in all the channels were fused together in a final decision-making system. Two different final decision making schemes using the majority voting and weighted combination based on consensual theory were considered. Simulations were performed on real data for six bands and on several images in order to account for the variations in size, shape, and contrast of the targets and also the signal-to-clutter ratio. The overall results showed the promise of the proposed system for detection and classification of mines and minelike tagets.     

Presentation modality and indirect performance information: Effects on ratings, reactions, and memory.

The authors investigated whether raters integrate indirect (second-hand) information from an employee's co-worker with their direct observations when completing performance evaluations. Performance levels of direct and indirect information and presentation modality (auditory vs. textual) were manipulated (N=220). Results showed that indirect information was perceived to be of highest utility when the performance levels of the direct and indirect information were consistent. Confidence in performance ratings was lowest when the indirect source delivered negative performance feedback that was contrary to the rater's own positive observations. Indirect information was only reflected in the performance ratings when direct observations were positive. There was a significant 3-way interaction between performance level of the direct information, performance level of the indirect information, and presentation modality on memory for performance incidents. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Can the combination of flaxseed and its lignans with soy and its isoflavones reduce the growth stimulatory effect of soy and its isoflavones on established breast cancer?

Consumption of phytoestrogen (PE)-rich foods (i. e., soy and flaxseed (FS)) is increasing because of their suggested health benefits. However, recent studies raise concern over the safety of soy and its isoflavones, particularly genistein (GEN), for postmenopausal breast cancer (BC), due to their potential stimulatory effects on human breast tissue and on the growth of existing tumors in rodents. FS, rich in PE lignans, which is metabolized to the mammalian lignans enterolactone (ENL) and enterodiol (END), has consistently been shown to have tumor inhibitory effects in a human clinical trial as well as rodent BC models. Using the preclinical athymic mouse postmenopausal BC model, combining FS with soy protein or GEN with END and ENL, was found to negate the tumor stimulatory effects of soy protein or GEN alone. The mechanism may be related to the modulation of estrogen receptor and MAPK signaling pathways. If these studies can be confirmed in clinical trials, then consumption of combined soy and FS, or their PEs, may reduce the tumor growth stimulatory effect of soy or GEN. This may indicate that if soy is consumed with lignan-rich foods, it may continue to induce its other beneficial health effects, without inducing adverse effect on postmenopausal BC.     

Aeration tank odour by dimethyl sulphoxide (DMSO) waste in sewage.

Sewage plants can experience dimethyl sulphide (DMS) odour problems by at least one mg/L dimethylsulphoxide (DMSO) waste residue in plant influent, through a DMSO/DMS reduction mechanism. This bench-scale batch study simulates in bottles the role of poor aeration in wastewater treatment on the DMSO/DMS and sulphate/H2S reduction. The study compares headspace concentrations of sulphide odorants developed by activated sludge (closed bottles, half full) after six hours under anoxic versus anaerobic conditions, with 0 versus 2 mg/L DMSO addition. Anoxic sludge (0.1 - 2 mg/L dissolved oxygen, DO) with DMSO resulted in about 50 ppmv DMS and no other sulphide, while DMSO-free sludge was free of detectable sulphides. Anaerobic sludge (no measurable DO to the point of sulphate reduction) with DMSO resulted in 22/4/37 ppmv of H2S/methanethiol (MT)/DMS, while DMSO-free sludge resulted in 44/8/2 ppmv of H2S/MT/DMS. It is concluded that common "anoxic" aeration tank zones with measurable DO in bulk water but immeasurable DO inside sludge flocs (nitrate reducing) experience DMSO reduction to DMS that is oxidation resistant and becomes the most important odorant. Under anaerobic conditions, H2S from sulphate reduction becomes an additional important odorant. A strategy is developed that allows operators to determine from the quantity of different sulphides whether the DMSO/DMS mechanism is important at their wastewater plant.     

Texture and training of magnetic shape memory foam

Magnetic shape memory alloys display magnetic-field-induced strain (MFIS) of up to 10% as single crystals. Polycrystalline materials are much easier to create but display a near-zero MFIS because twinning of neighboring grains introduces strain incompatibility, leading to high internal stresses. Pores reduce these incompatibilities between grains and thus increase the MFIS of polycrystalline Ni–Mn–Ga, which after training (thermo-magneto-mechanical cycling) exhibits MFIS as high as 8.7%. Here, we show that this training effect results from a decoupling of struts surrounding pores in polycrystalline Ni–Mn–Ga during the martensitic transformation. To show this effect in highly textured porous samples, neutron diffraction measurements were performed as a function of temperature for phase characterization and a method for structure analysis was developed. Texture measurements were conducted with a magnetic field applied at various orientations to the porous sample, demonstrating that selection of martensite variants takes place during cooling.     

Rare‐Earth Dopant Effects on the Structural,Energetic, and Magnetic Properties of Alumina from First Principles

Density functional theory was used to study the effect of rare‐earth dopants on the structure, phase stability, and magnetic properties of α‐ and θ‐Al₂O₃. Lanthanide series rare‐earth dopants (Pr, Nd, Gd, Er, and Yb) were considered at a doping concentration of 0.83 at.%. Incorporation of rare‐earth dopants was found to increase the lattice parameters and exaggerate the local structural distortion around the dopant. The extent of local lattice distortion was correlated with the dopant ionic radii. The phase stability of rare‐earth‐doped Al₂O₃ was assessed by comparing cohesive and defect formation energies for doped and undoped α‐ and θ‐Al₂O₃. Rare‐earth dopants increased the relative stability of the metastable θ‐Al₂O₃, although doped α‐Al₂O₃ remained more stable. The total magnetic moment of the doped Al₂O₃ was shown to correlate with the number of unpaired electrons. The magnetic moment was also found to be strongly localized on the rare‐earth dopant for Er, Gd, Nd, and Pr‐doped Al₂O₃. In contrast, the Yb dopant induced a delocalized magnetic moment on ~80% of the oxygen atoms. These results further the understanding of dopant incorporation mechanisms, as well as the doping effect on phase stability and magnetic properties that may be applied to advanced field‐assisted material synthesis and processing for enhanced properties.