A thermodynamic estimation of the minimum concentration attainable in a flow-through porous electrode reactor

The minimum concentration attainable in a porous flow-through reactor is estimated by applying the thermodynamics of electrochemical cells with a knowledge of the maximum reactor operating potential. This predicted concentration is the equilibrium wall concentration at the back of the reactor and is qualitatively compared to the experimentally measured minimum average bulk values observed by various authors for the deposition of copper, silver, lead, and mercury, and for the oxidation of ferrous ions. It is suggested that a knowledge of the current versus reactor operating potential will elucidate the lower limits observed for any metal system. In particular, the case of antimony removal is discussed.     

Effects of cholinergic agonists and antagonists on self-stimulation behavior in the rat.

Trained 23 male Wistar albino rats to press a bar for electrical stimulation of the brain on a 30-sec variable-interval schedule. Ss were tested weekly with 1 or more of the following drugs: physostigmine (50-400 MUg/kg), neostigmine (25-200 MUg/kg), atropine (2-16 mg/kg), methylatropine (2-16 mg/kg), scopolamine (400-1,600 MUg/kg), pilocarpine (500-4,000 MUg/kg), nicotine (100-800 MUg/kg), mecamylamine (1 mg/kg), and methamphetamine (500 MUg/kg). Results support the suggestion that the cholinergic system is composed of 2 reciprocally related components: (a) a muscarinic "no-go" portion, whose activation has an inhibitory effect on self-stimulation; and (b) a nicotinic "go" portion, whose excitatory effect on self-stimulation is (most probably) mediated by norepinephrine. (33 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Coordinated morphogenesis of epithelia during development of the Caenorhabditis elegans uterine-vulval connection

Development of the nematode egg-laying system requires the formation of a connection between the uterine lumen and the developing vulval lumen, thus allowing a passage for eggs and sperm. This relatively simple process serves as a model for certain aspects of organogenesis. Such a connection demands that cells in both tissues become specialized to participate in the connection, and that the specialized cells are brought in register. A single cell, the anchor cell, acts to induce and to organize specialization of the epidermal and uterine epithelia, and registrates these tissues. The inductions act via evolutionarily conserved intercellular signaling pathways. The anchor cell induces the vulva from ventral epithelial cells via the LIN-3 growth factor and LET-23 transmembrane tyrosine kinase. It then induces surrounding uterine intermediate precursors via the receptor LIN-12, a founding member of the Notch family of receptors. Both signaling pathways are used multiple times during development of Caenorhabditis elegans. The outcome of the signaling is context-dependent. Both inductions are reciprocated. After the anchor cell has induced the vulva, it stretches toward the induced vulval cells. After the anchor cell has induced specialized uterine intermediate precursor cells, it fuses with a subset of their progeny.     

Interactive effects of depression symptoms, nicotine dependence, and weight change on late smoking relapse.

Signal detection methods were used to develop an algorithm useful in distinguishing those at risk for late relapse from those likely to maintain abstinence. Four subgroups with 24-month survival (nonrelapse) rates ranging from 79% to 33% were identified. Among participants whose depression symptoms decreased from baseline to the end of treatment, lower levels of nicotine dependence were associated with less relapse at the 24-month follow-up (odds ratio?=?2.77; 95% confidence interval: 1.36–5.62). Among participants whose depression symptoms increased from baseline to the end of treatment, greater weight gain was associated with less relapse at follow-up (odds ratio?=?2.90; 95% confidence interval: 1.41–5.96) . This study suggests that it may become possible to use both baseline and treatment information to "titrate" interventions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Electrochemical peroxidation of contaminated aqueous leachate

The landfill process for disposal of domestic waste produces a large volume of contaminated aqueous leachate. This study was aimed at investigating the feasibility of using electrochemical peroxidation (ECP) for the treatment of this leachate. ECP is a process by which aqueous, or suspended organic matter, is oxidised by the action of hydroxyl free radicals, produced using hydrogen peroxide and cast iron or mild steel electrodes. The effectiveness of the ECP process was quantified by measuring reductions in leachate biological oxygen demand (BOD) and chemical oxygen demand (COD) as a result of treatment. Optimisation of the process was carried out by varying electrode voltage, polarity switching rate, leachate pH and hydrogen peroxide concentration. This resulted in an observed BOD reduction of 36% and COD reduction of 52%, which was achieved by adjusting the pH to 4.0, applying an electrode voltage of 1.9V and switching speed of 5 cycles per minute. The optimum hydrogen peroxide concentration was found to be 100ppm. In addition to reductions in BOD and COD, reductions in chloride and ammonium levels were measured and found to be 15% and 18% respectively. The results of the investigation indicate that the ECP process is effective in the treatment of landfill leachate, and suggest that with further optimisation, ECP may serve as an attractive alternative to current biological leachate treatment methods.     

Workshop on hydrogen effect in InP and related compounds

One of the primary technological interests in hydrogen in semiconductors concerns the ease with which it is introduced during crystal growth and processing. Hydrogen can move during device operations and hence alter device characteristics. It is thus necessary to understand how hydrogen is introduced in semiconductors and to be able to detect its presence. Thus, in order to give potential answers to these problems, several topics were discussed. They covered all the hydrogenation effects through : device-related applications, hydrogen-surface interaction, acceptors and donor passivation, unintentional hydrogénation, proton implantation and related problems. Finally, unsolved issues are reviewed in a final talk.     

Mucogingival orthodontic and periodontal problems

Di-n-butyltin diacetate (DBTA) has been shown previously to cause malformations such as cleft mandible, ankyloglossia and fused ribs in rat foetuses after oral treatment of dams on day 8 of gestation. In this study, effects of pretreatment with carbon tetrachloride (CCl4) on the teratogenic activity of DBTA were examined in Wistar rats. Pregnant rats were pretreated sc with CCl4 (0.5 ml/kg) on days 6 and 7 of gestation and were treated orally with DBTA on day 8 of gestation at doses of 0, 4.5, 10 or 22 mg/kg. Caesarean sections were performed on day 20 of gestation, and foetuses were examined for external and skeletal anomalies. Pretreatment with CCl4 enhanced the incidence of external and skeletal malformations caused by DBTA. Concentrations of di-n-butyltin in embryos, maternal liver and maternal blood on day 9 of gestation were increased by CCl4 pretreatment, which inhibited the activity of maternal hepatic microsomal drug-metabolizing enzymes. These results suggest that there is little probability that metabolites of DBTA make a critical contribution to the teratogenicity of DBTA.     

Failure of hierarchical distributions of fibre bundles. I

We consider by computational and analytic means the failure properties of hierarchically organized bundles of fibres with equal load sharing, a problem that may be treated exactly by renormalization methods. We show, independent of the specific failure properties of an individual fibre, that the threshold for failure of a fibre bundle obeys a universal scaling law with respect to the size of the bundle. Moreover, this scaling law is preserved for any hierarchical organization of fibre bundles.