Investigation of the selective catalytic reduction of NO by NH3 on Fe-ZSM5 monolith catalysts

Photocatalytic nitric oxide (NO) decomposition and reduction reactions, using carbon monoxide (CO) as a reducing gas, have been investigated over Degussa P25 titanium dioxide photocatalysts, using a continuous flow reactor. The effects of thermal pretreatment temperature and reaction gas composition on the activity and selectivity of the decomposition and reduction reactions have been evaluated. Prepared materials were characterised by X-ray diffraction (XRD), N₂ physisorption, transmission electron microscopy (TEM) and differential scanning calorimetry (DSC) and findings from these techniques were used to explain the observed photocatalytic properties. XRD and TEM results indicated that for the pretreatment temperatures used (70, 120, 200, 450 and 600 °C) there was no appreciable change in the phase composition and the original composition of ca. 77 vol.% anatase and 23 vol.% rutile was maintained even after treatment at 600 °C. It was found that the photocatalytic activity for both the decomposition and reduction reactions decreased with increasing pretreatment temperature. This was attributed to the removal of surface hydroxyl species that act as active sites for reaction. For the decomposition reactions the only products observed were nitrogen and nitrous oxide and the selectivity for nitrogen formation remained constant (ca. 23%) regardless of the pretreatment temperature. The presence of CO in the reaction gas had a dramatic effect on the selectivity of the reactions with nitrogen selectivities as high as 65% being observed. It was found that as the CO/NO ratio increased the selectivity for nitrogen formation increased.     

Characterization of different bondings in some divalent metal niobates of columbite structure

The structural characteristics of the columbite niobates MNb₂O₆ (M = Mg, Ca, Mn, Fe, Co, Ni, Cu, Zn, Cd) from their X ray diffraction powder patterns and indexed according to the Pbcn space group are given. Cell parameters are refined for each compound. Previous spectroscopic studies by normal coordinate analysis provide the basis for a discussion of the precise nature of the NbO and MO bonds. Force constants and bond order are given and the influence of the electronegativity of the M²⁺ cations upon these bonds is shown.     

The influence of depressive symptomatology on episodic memory functioning among clinically nondepressed older adults.

The authors examined a community-based sample of 303 clinically nondepressed individuals aged 75 through 96 years on 4 recall tasks: free recall of rapidly presented random words, free recall of slowly presented random words, free recall of organizable words, and cued recall of organizable words. Using a classification taxonomy that identified mood- and motivation-related symptoms of depression, it was found that motivation-related symptoms had a negative effect on performance across all tasks, whereas mood-related symptoms had no effects. In addition, motivation-related symptoms negatively influenced the ability to benefit from more study time but had no effect on the ability to make use of item organization or category cues. An analysis of the specific motivation-related symptoms suggested that symptoms that may affect the ability to focus and sustain attention (e.g., concentration difficulties, lack of interest ) were most strongly associated with performance deficits. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparisons of rating scales of child psychopathology in clinic and nonclinic samples.

Mothers of 45 control and 35 clinic children (mean ages 7.6 and 7.5 yrs, respectively) completed 2 factor-analytically derived rating scales of child psychopathology, the Behavior Problem Checklist and the Parent Questionnaire. Intercorrelations among factors indicated some factor overlap and some differences between apparently similar factors. Conduct problem ratings on the Behavior Problem Checklist covaried with ratings of conduct problems, hyperactivity, and learning problems on the Parent Questionnaire. Patterns of correlations suggested that mothers of nonreferred children rated pathology per se, whereas mothers of referred children rated behaviors that fell into internalizing and externalizing clusters. Teachers asked to rate 22 referred and 22 control males (mean ages 8.3 and 8.5 yrs, respectively) on the Behavior Problem Checklist and the Teacher Rating Scale showed more consistency in the behaviors rated. It is concluded that, although similar factor labels are used from scale to scale, they reflect somewhat different behaviors and are influenced by the child's clinical status, the rater's past experience with children, and specific scale characteristics. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cheek cell fatty acids as indicators of dietary lipids in humans

Analysis of cheek cell lipids has been suggested as a noninvasive method for monitoring the fatty acid composition of diets in humans. In a pilot study conducted to determine the validity of the method, cheek cell samples were collected from subjects consuming a low fat (20% of calories) diet consisting of fatty acids with either a 1.0 or 0.3 P/S ratio. Neither total lipid nor polar lipid fatty acids in cheek cells consistently reflected the P/S ratio of the diets. However, there were trends, particularly in the nonpolar lipids, suggesting that cheek cell fatty acid ratios might be useful for monitoring the fatty acid composition of the diets. The diet with the higher P/S ratio (1.0 vs 0.3) consistently resulted in cheek cell lipids with lower ratios of 18∶1/saturated fatty acids and greater 18∶2/20∶4, 18∶2/18∶1 and 18∶2/18∶0 fatty acid ratios.     

Purification and characterization of a dipeptidase from Lactobacillus delbrueckii subsp. bulgaricus

A metal-dependent dipeptidase has been purified from a cell-free extract of Lactobacillus delbrueckii subsp. bulgaricus B14 by ammonium sulphate precipitation, anion exchange chromatography, metal chelating affinity chromatography with immobilized Cu²⁺, and repeated FPLC anion exchange chromatography. The molecular mass of the purified enzyme was estimated to be 51 kD by SDS-polyacrylamide gel electrophoresis as well as by gel filtration, which indicates that it does not consist of subunits. The enzyme was most active at pH 7 and 50°C. Reducing agents, like dithiothreitol and β-mercaptoethanol, increased enzyme activity while metal chelating agents had an inhibitory effect. Enzyme activity, inhibited by EDTA and EGTA, could be partially restored by Co²⁺ and Mn²⁺. The enzyme was most active on dipeptides containing an aminoterminal hydrophobic amino acid such as Leu-Leu and Leu-Gly. Kinetic studies indicated that the dipeptidase had a higher affinity for the first substrate mentioned. The K_m-values for both substrates were about 0·56 and 1·23 mM, with turnover numbers of 870 and 480 s⁻¹, respectively.     

Cytotoxic Rhodium(III) and Iridium(III) Polypyridyl Complexes: Structure–Activity Relationships,Antileukemic Activity,and Apoptosis Induction

Whereas the cytostatic agents mer‐[RhX₃(DMSO)(pp)] (X=Cl, Br; pp=phen, dpq) are considerably more potent than their facial isomers, this order is reversed for the analogous kinetically more inert Ir^III polypyridyl complexes. The complexes induce specific apoptotic cell death in leukemia and lymphoma cells via the intrinsic mitochondrial pathway and cause negligible necrotic damage.