X-ray photoelectron spectroscopic study of the oxidation and reduction of a cerium(III) oxide/cerium foil substrate

X-ray photoelectron spectroscopy has been used to examine the nature of the oxide overlayers on a passivated cerium metal foil as a function of a variety of oxidation and reduction treatments. Oxidation of a clean uncontaminated cerium(III) oxide surface is facile at room temperature and produces non-stoichiometric ceria (CeO_2–x) at oxygen doses as low as 10 L. At higher doses the overlayer thickens, and after a dose of 160 L the layer depth exceeds the Ce 3d photoelectron attenuation distance of about 20 Å. High pressure treatment of the foil in oxygen (0.5 bar at RT and 473 K) produces CeO₂ in a high degree of crystallographic order such that O 1s photoelectron intensities are increased above that expected from a randomly oriented powder. An attempt to reduce the CeO₂ layer formed by controlled oxidation with CO (633 K, 14 h, 0.6 bar) results in the formation of a carbonated surface layer. Results following attempts to reoxidise this layer are discussed.     

Protein engineering of alcohol dehydrogenases; effects of amino acid changes at positions 93 and 48 of yeast ADH1

By protein engineering we have investigated changes to two aminoacid residues (Trp93 and Ser48) in the substrate pocket of yeastalcohol dehydrogenase 1. Upon changing Thr48 to serine we producedan enzyme which has markedly greater activity towards aliphaticalcohols with chain length up to 8, together with a generalincrease in catalytic activity (V/K). Changes at position 93were less pronounced, with the Phe enzyme being more activethan the parent towards the range of alcohols but with the alanineenzyme showing very little difference from the wild-type. Enzymeswith the double changes at 48 and 93 showed increased activitytowards alcohols with 3–8 carbons but the increases werenot additive over the single changes. The enzymes with changesat the two positions would metabolize both stereoisomers of2-octanol whereas the parent ADH would attack only one of them.None of the engineered enzymes would attack cyclohexanol oraromatic alcohols. The results are in general agreement withthe prediction that reducing the size of amino acids in thesubstrate pocket would enhance the ability to oxidize alcoholslarger than ethanol.     

Does Transcendental Meditation training affect grades?

70 students who took a Transcendental Meditation (TM) Technique Initiation Training program were matched on the basis of sex, college, year, prior grades, and 1st letter of last name with students who had not undergone TM training. The TM group did not differ in GPA from the control group for the academic quarter after training. The same was true for subgroups of 42 matched pairs 2 quarters after training. No effect upon grades was demonstrated for TM training. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development of a dosing strategy for a heavy-duty diesel exhaust cleaning system based on NOX storage and reduction technology by Design of Experiments

A dosing strategy for the transient control of an exhaust after-treatment system using the NO_X storage and reduction approach was developed on a heavy-duty diesel engine rig equipped with an 11 l diesel engine. The catalysts were oxidation catalysts of 8.4 l and NO_X storage and reduction catalysts of 16.8 l total volume. The dosing strategy has been tested in a European Transient Cycle (ETC) resulting in a NO_X reduction of 60% (by 4.5 g/kWh) with a fuel penalty of 6.6% when the catalysts were preconditioned to 450 °C. The reducing agent was diesel fuel. To keep the fuel penalty low, a bypass system was used which bypassed approximately 90% of the exhaust flow under the regeneration periods. The parameters for the dosing strategy were obtained from steady-state optimization experiments (constant speed and torque) using Design of Experiments (DoE) to obtain much information from few experiments. The system was optimized for a high degree of NO_X reduction with a low fuel penalty. The period when the flow through the catalyst is reduced (bypass time), the cycle time, the injection time and rate are important parameters to achieve an improved NO_X reduction. The optimal values of these parameters varied with the load points used. The steady-state NO_X conversion was approximately 60% (3.3–4.1 g/kWh) at catalyst temperatures between 330 and 530 °C. The most promising parameters for a large NO_X reduction and a low fuel penalty have been applied in the dosing strategy and tested in an ETC.     

Enhanced analyte detection using in-source fragmentation of field asymmetric waveform ion mobility spectrometry-selected ions in combination with time-of-flight mass spectrometry

Miniaturized ultra high field asymmetric waveform ion mobility spectrometry (FAIMS) is used for the selective transmission of differential mobility-selected ions prior to in-source collision-induced dissociation (CID) and time-of-flight mass spectrometry (TOFMS) analysis. The FAIMS-in-source collision induced dissociation-TOFMS (FISCID-MS) method requires only minor modification of the ion source region of the mass spectrometer and is shown to significantly enhance analyte detection in complex mixtures. Improved mass measurement accuracy and simplified product ion mass spectra were observed following FAIMS preselection and subsequent in-source CID of ions derived from pharmaceutical excipients, sufficiently close in m/z (17.7 ppm mass difference) that they could not be resolved by TOFMS alone. The FISCID-MS approach is also demonstrated for the qualitative and quantitative analysis of mixtures of peptides with FAIMS used to filter out unrelated precursor ions thereby simplifying the resulting product ion mass spectra. Liquid chromatography combined with FISCID-MS was applied to the analysis of coeluting model peptides and tryptic peptides derived from human plasma proteins, allowing precursor ion selection and CID to yield product ion data suitable for peptide identification via database searching. The potential of FISCID-MS for the quantitative determination of a model peptide spiked into human plasma in the range of 0.45-9.0 μg/mL is demonstrated, showing good reproducibility (%RSD < 14.6%) and linearity (R(2) > 0.99).     

A Versatile Particle Beam Interface for Coupling Hplc to Ion Trap,Quadrupole and Sector Mass Spectrometers

Abstract

A two-stage particle beam LC-MS interface, capable of being coupled to a quadrupole, sector or ion trap mass spectrometer, is described. The device has a modular design, allowing operating parameters to be easily optimized whilst in use. Successful coupling to a quadrupole ion trap mass spectrometer (ITMS) is achieved using a novel heated transfer line for analyte vaporization and scan routines which eliminate solvent ion effects.     

Effects of response style on the Occupational Scales of the Strong-Campbell Interest Inventory.

When an answer sheet for the Strong-Campbell Interest Inventory is marked with all likes (L), all indifferences (I), or all dislikes (D), the resulting Occupational Scale (OS) scores reflect the use of either L, I, or D responses on each scale. The word skeleton has been coined for such a profile because it shows the bare bones of the test construction. When a student's response style is also greatly skewed, the OS profile tends to reflect the pattern of the underlying skeleton rather than the student's own interests. In the present study, correlating the skeleton profiles with college students' profiles showed that the common variance may average around 35% when a predominance of any one response (L, I, or D) reaches 60%. Ns for the comparison sets ranged from 712 to 836. A factor analysis of a structured sample of 24 high-L, high-I, and high-D students from engineering, business administration, liberal arts and sciences, architecture, art, and urban planning resulted in factors related to response style rather than curricula. (7 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evaluation of a NO x reduction system on an engine rig under stationary operation

Topics in Catalysis - The NO x storage and reduction approach was applied on a full-scale engine rig under stationary operation. NO x reduction experiments were performed and a catalyst model...