Photodegradation of sulphadimethoxine in water by medium pressure UV lamp

The photodegradation rate of sulphadimethoxine (SMT) in water was studied under polychromatic UV light, in a bench scale apparatus. SMT photolysis was carried out at pH levels of 2.5, 6.5 and 10 to study the impact of acid base properties on the degradation of SMT. The highest SMT photolysis fluence based rate was found at pH=2.5 (k=7.22x10(-4) cm2/mJ) and the lowest rate at pH=10 (k=4.72x10(-4) cm2/mJ), thus the reaction rate decreases with an increase in pH between pH values of 2.5-10. Results indicated that direct photolysis is not satisfactory for degradation of SMT by polychromatic UV lamp as a fluence of approximately 7,000 mJ/cm2 is needed to break down 99% of SMT at pH 6.5. The photodegradation products of SMT were studied at various pH values. Photodegradation of SMT results in dissimilar relative amounts of intermediates formed at different pH values which may exert a photon demand and impact on SMT photodegradation rate.     

Relative importance of informational units and their role in long-term recall by closed-head-injured patients and control groups.

Applied qualitative analysis to the information recalled by control Ss and closed-head-injured (CHI) patients. The Logical Memory subtest of the Wechsler Memory Scale (WMS) was administered to 40 CHI and 40 control Ss. Recall was tested immediately after administration, 40 min later, and 24 hrs later. The analysis took into account the importance of recalled information as determined by a prior rating according to 3 levels of importance. Results suggest that CHI patients have difficulty selectively retrieving the most important information after a long delay. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role of zirconium in the phase formation at the interdendritic zone in nickel-based superalloys

A commercial Alloy 80A and a modified alloy with lower titanium and zirconium contents, e.g. 1.4% and <0.01%, respectively, were subjected to unidirectional solidification followed by a rapid quench in water to preserve the structure at elevated temperatures. The slow solidification results in a coarse dendritic structure with a high enrichment of sulphur (up to 2%), aluminium (up to 4%), titanium (up to 13%) and zirconium in the interdendritic zones. In the commercial Alloy 80A, the zirconium and sulphur present in the interdendritic zone result in a eutectic containing ZrS and NiCrTi-matrix. Excess zirconium forms an NiZr-intermetallic. No TiS is formed in this case. In the absence of zirconium, the titanium enriched in the interdendritic residual melt forms a eutectic of TiS. In both cases the effective solidus temperature corresponding to the composition of the residual melt is 1170°C, compared to 1330 °C, which is the solidus temperature of the bulk material.     

Identification of Main Lipid Components of Mole Rat Harderian Gland

The Harderian gland of the mole rat has been demonstrated to have appeasement qualities on conspecifics. In this study total lipid content of the Harderian gland of the mole rat was evaluated and analyzed by means of thin-layer chromatography (TLC), densitometry, gas chromatography–mass spectrometry (GC-MS), FAB-MS, and NMR. More than 50% of the gland's fresh weight is composed of lipids, making it the highest Harderian gland lipid content ever found in rodents. Male and female lipid components differ considerably. Both have wax esters as the main lipid component, but in females the alcohol components were usually chains of 12 carbons, while in males they were mostly chains of 16 carbons. In addition, while in females the fatty acid residues were usually saturated, in males there was a double bond in the middle of the chain. As many as 25 different esters were found in females, and only seven in males. However, in the male an unusual volatile compound identified as 1-(3)-hexenyl-benzene was found. This sexual dimorphism may show that the gland function is sex-specific, and gives support to our earlier reports that the mole rat Harderian gland may be a source of pheromones.     

Removal of pharmaceuticals using combination of UV/H(2)O(2)/O(3) advanced oxidation process

Water and wastewater effluents contain a vast range of pharmaceutical chemicals. The present study aims to determine the potential of the advanced oxidation technology UV/H(2)O(2)/O(3) and its sub-processes (i.e. UV, UV/H(2)O(2), UV/O(3), O(3) and H(2)O(2)/O(3)) for the degradation of the antibiotics ciprofloxacin (CIP) and trimethoprim (TMP), and the antineoplastic drug cyclophosphamide (CPD) from water. Creating AOP conditions improved in most cases the degradation rate of the target compounds (compared with O(3) and UV alone). H(2)O(2) concentration was found to be an important parameter in the UV/H(2)O(2) and H(2)O(2)/O(3) sub-processes, acting as (?)OH initiator as well as (?)OH scavenger. Out of the examined processes, O(3) had the highest degradation rate for TMP and H(2)O(2)/O(3) showed highest degradation rate for CIP and CPD. The electrical energy consumption for both CIP and CPD, as calculated using the E(EO) parameter, was in the following order: UV > UV/O(3) > UV/H(2)O(2)/O(3) > O(3) > H(2)O(2)/O(3). Whereas for TMP O(3) was shown to be the most electrical energy efficient. Twelve degradation byproducts were identified following direct UV photolysis of CIP.     

Phase transformations in permanent-mould-cast aluminium bronze

The phases obtained in aluminium bronze (Cu-10Al-4Fe) cast into a permanent mould were investigated. The parameters examined were the pre-heating temperature of the mould and the graphite coating thickness. The phases and ₂ were detected as well as the metastable phases and . The intermetallics of the system Fe-Al were obtained in various stoichiometric compositions. The different cooling rates of the casting resulted in two mechanisms of transformation to grains out of the unstable phase, one being nucleation and growth producing needle-shaped grains, the other exhibiting a massive transformation to spherical grains. These two mechanisms determine the changes in the size of the a grains as result of changes in the cooling rate in its various ranges.     

Initial impact of the Gabčíkovo hydroelectric scheme on the species richness and composition of 0+ fish assemblages in the Slovak flood plain,River Danube

Relatively little information exists on the effects of hydroelectric schemes on 0+ fish composition in large European rivers because few or no pre‐impact data exist. We compared 0+ fish species richness and composition, relative density, fish size as well as available and used habitat using data from 12 floodplain sites sampled just prior to (1992) and four years after (1996) the start of operations of the Gab?íkovo hydropower station on the River Danube (Slovakia). We also used modelling techniques to assess the change in species richness and habitat use and to predict 1996 occurrences from the 1992 data set. The floodplain was greatly modified by the hydroscheme. Only 12 of 27 sites sampled in August 1992 were extant in August 1996. Therefore, all four channel types identified (flowing, abandoned, weir, wing‐dam) were more lentic in 1996 than in 1992, with increased width, smaller‐sized sediment (silt, clay) and greater amounts of macrophytes. After the operations of the hydroscheme, the overall relative density of fishes (individuals per surface area) of all ages decreased, with the exception of 0+ fishes, despite a slight reduction in 0+ fish density in all channel types except weirs. Species number increased from 25 to 28, although in all channel types there was a change in the composition of the 0+ fish assemblages, with rheophiles generally replaced by limnophiles and migrants from the lower Danube. The two most important microhabitat variables were the proportion of macrophytes and gravel, the latter being the factor distinguishing 0+ fish microhabitat use in 1992 (preferences) and 1996 (indifference or avoidance). Species richness and 0+ fish density in 1996 could be predicted from the 1992 data using simple log‐linear models (density, richness, sample number). Species‐specific occurrence in 1996 could not be predicted using environmental/fish data from 1992 with multiple regression or generalized additive models (GAM). However, the overall GAM from 1992 could predict overall fish occurrence in 1996. Copyright © 2003 John Wiley & Sons, Ltd.     

Anoxic LTP is mediated by the redox modulatory site of the NMDA receptor

1. The effects of redox reagents, 5,5'-dithiobis-2-nitrobenzoic acid (DTNB) and tris(carboxyethyl)phosphine (TCEP), on anoxia-induced long-term potentiation (LTP) were investigated in CA1 hippocampal neurons using extracellular recording techniques. Experiments were performed in the presence of 0.1 mM MgCl2 and 10 microM 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) to pharmacologically isolate N-methyl-D-aspartate (NMDA) receptor-mediated responses. 2. DTNB (200 microM), a thiol oxidizing reagent, reduces by 52 +/- 9% (mean +/- SE) (n = 9/9) NMDA-receptor field potentials evoked by electrical stimulation of Schaffer collaterals and this effect could not be reversed by extensive washing. Nearly the same reduction of the initial response was obtained with different concentrations of DTNB (100 and 500 microM), but the time required to reach the maximal inhibition was concentration-dependent. 3. In keeping with an earlier study oxygen and glucose deprivation for 2-3 min induced a long-term potentiation (LTP) of the NMDA receptor response (+65 +/- 16%, n = 4/6). This potentiation was reversed by DTNB (100-500 microM) (-47 +/- 18%; n = 4/4) and the initial LTP could not be restored upon extensive washing of the drug. 4. TCEP (200 microM), a reagent which reduces S-S bond, amplified the electrically evoked NMDA-receptor EPSP (+27 +/- 12%; n = 3). In addition, TCEP (200 microM), nearly completely reversed the effect of DTNB (200 microM) on anoxia-induced LTP (+56 +/- 19%; n = 3/3). Preliminary results also indicate that TCEP occlude anoxic-LTP (n = 3/4). 5. Following DTNB (200 microM) treatment, oxygen and glucose deprivation did not generate anoxic LTP and extensive washing did not restore a potentiated NMDA field potential. 6. These observations strongly suggest that the redox site of the NMDA receptor is involved in the induction and the maintenance of the anoxic LTP of the NMDA receptor-mediated response in CA1.