Hydrogen Oxidation Catalyzed by Pt Supported on Carbon Nanofibers with Different Graphite Sheet Orientations

The kinetic study of hydrogen oxidation with or without the presence of CO has been used as a tool to study the relative oxygen and CO adsorption strength on Pt nanoparticles, which are important parameters for fuel cell catalysts. It was found that the activation energy, which is determined by the oxygen binding energy, is influenced by the CNF graphite sheet orientation, CNF oxygen groups and catalyst preparation method. A weaker bonding of oxygen was indicated for Pt nanoparticles supported on platelet compared to Pt on fishbone CNFs. Moreover, oxygen seemed to be more strongly bonded to Pt particles on CNFs prepared by deposition–precipitation compared to those prepared by incipient wetness impregnation and a metal-oxide colloid method. Enhanced CO-adsorption was indicated for Pt supported on carbon nanofibers with introduced oxygen groups.     

Influence of Synthesis Conditions for ZSM-5 on the Hydrothermal Stability of Cu-ZSM-5

The influence of syntheses parameters of zeolite ZSM-5 on the lean NO _x reduction activity and hydrothermal stability of Cu-ZSM-5 has been investigated. The hydrothermal stability of Cu-ZSM-5 was found to depend on the aluminium source used and on the presence of Ca(OH)₂ in the synthesis mixture for ZSM-5.     

Keeping up with the neighbours--measuring the bystander response

Ionising radiation can induce responses within non-exposed neighbouring (bystander) cells, which potentially have important implications on the estimates of risk at environmentally relevant doses. Using human skin fibroblasts (AG1522), a range of methods were used to investigate the nature of the signal(s) arising from the exposed cells. The signal(s) can be transmitted by direct cell-cell communication (investigated by using partial dish irradiations) or by medium-borne factors (a co-culture system where two monolayers share the same medium but only one monolayer is exposed to ionising radiation). CDKN1A was found to be up-regulated in both directly exposed and non-exposed cells. The data suggest that direct cell-cell communication dominates for these confluent cells, with medium-borne factors also contributing.     

On multi‐cell admission control in CDMA networks

We consider a multi‐cell (MC) code division multiple access (CDMA) system that supports multiple service classes, including peak rate allocated and elastic ones. Peak rate allocated sessions—when admitted into the system—transmit at a constant bit rate, while elastic sessions can be slowed down at the expense of increasing their residency time. Admitted sessions cause an instantaneous bit rate‐dependent interference in neighbour cells. In this rather general setting, we propose a method to calculate the class‐wise blocking probabilities as the functions of the estimated so‐called inter‐cell coupling factors. In the paper this coupling factor is the ratio between the uplink path gains to different Node‐B:s (that can be easily obtained in a CDMA system from pilot measurement reports), but our model could include other coupling measures as well. We find that when these coupling factors are underestimated, the system may get into false states (FSs) or false rate states (FRSs) that lead to violating the noise rise threshold. As traffic becomes increasingly elastic, the probability of FSs decreases, but the probability of FRSs increases. Based on numerical results, we make the point that as the traffic becomes more elastic, avoiding the underestimation of these coupling factors as well as exercising MC admission control plays an increasingly important role in guaranteeing proper service quality. Copyright © 2007 John Wiley & Sons, Ltd.     

Relationships between storage protein composition,protein content,growing season and flour quality of bread wheat

The storage protein composition from the Glu‐1, Glu‐3 and Gli‐1 loci encoding high and low molecular weight glutenin subunits (HMW‐GS and LMW‐GS) and gliadins, respectively, was determined on 30 wheat (T aestivum L) genotypes from three growing seasons. The gliadins and the LMW‐GS were identified as gliadin/LMW‐GS pairs. All samples were analysed by two one‐dimensional electrophoretic techniques, and selected samples were also subjected to two‐dimensional electrophoretic separation. Different statistical/data‐analytical techniques were evaluated in the study of how the presence or absence of the protein alleles, the protein content and the growing seasons are related to flour quality. The year of growth had a large impact on mixograph peak time. When predicting mixograph peak time from the presence or absence of significant proteins and the year of growth, 70% of the variability in mixograph peak time could be explained, whereas only 49% of the variability could be explained when the year of growth was deleted from the model. Protein had no effect on mixograph peak time as expected, and the well‐known positive effect of HMW‐GS 5 + 10, and the negative effects of 2 + 12 and 6 + 8 was observed. Furthermore, some of the gliadin/LMW‐GS combinations influenced mixograph peak time significantly. The gliadin/LMW‐GS at the combined Gli‐A1, Glu‐A3 loci b; ?? was positively related to mixograph peak time, whereas ??; ?? and a;a was negatively related. Although the LMW‐GS component ?? of the alleles b; ?? and ??; ?? alleles appear similar on one‐dimensional gels, two‐dimensional separation of selected samples may suggest that the ?? components in these alleles are different proteins. Cross‐validated partial least squares regression combined with empirical uncertainty estimates (jack‐knifing) of the parameters estimated in the model, gave similar results to ANOVA in identifying quality related protein alleles. The applicability of the multivariate approach in proteomics is, however, much wider. Copyright © 2004 Society of Chemical Industry     

Study of the NaBH4–NaBr system and the behaviour of its low temperature phase transition

A mechano-chemical method was used to synthesize solid solution Na(BH₄)_1-xBr_x with 0 ≤ x ≤ 1. Samples with compositions of x ≤ 0.333 were annealed, in order to form a single phase material. Bromide substitution leads to smaller unit cell size and lower temperature and enthalpy of the order-disorder phase transition of NaBH₄. There is a linear relation between the amount of substitution, the temperature, the enthalpy and the kinetics of the phase transition. This linear relation between enthalpy and amount of substitution can be expressed by the function ΔH = ?6.268x + 1.206 where x is the amount of substitution and ΔH is the enthalpy.     

FEM simulation supported evaluation of a hydrogen grain boundary diffusion coefficient in MgH2

The diffusion coefficient data of hydrogen in the Magnesium-hydrogen system shows a large scatter, their trends extrapolations vary at room temperature between 10^?12 m²/s and 10^?29 m²/s. At room temperature the hydrogen diffusion coefficient in MgH₂ is, thus, uncertain by about 17 orders of magnitude. This may be partially attributed to grain boundaries contributing to the measured diffusion coefficient. In this paper we use finite-element (FEM) simulations to evaluate the influence of the grain boundary diffusion on the measured total diffusion depending on the difference of the grain boundary (D_GB) and volume (D_V) diffusion coefficients, as well as on the grain size. These results will be compared to Harrisson's analytical solutions. When the diffusion coefficients differ by more than D_V < 10^?3·D_GB, Harrison's diffusion regime C becomes the best way to describe the total diffusion. The results are used to re-interpret literature data on hydrogen diffusion in MgH₂ from this grain boundary contribution point of view. At 300 K, a hydrogen grain boundary diffusion coefficient ranging from D_GB = 10^?17 m²/s to D_GB = 10^?20 m²/s, depending on the individual type of sample in MgH₂, results from the data evaluation.     

A GC–MS-based metabonomic investigation of blood serum from irritable bowel syndrome patients undergoing intervention with acidified milk products

In the present study, the use of gas chromatography mass spectrometry (GC–MS)-based metabonomics to characterize blood serum in an intervention study of patients suffering from the common gastrointestinal disorder irritable bowel syndrome (IBS) was investigated. The patients included in the study consumed an acidified milk product with (n = 30) or without probiotics (n = 31) (Lactobacillus paracasei F19, Lactobacillus acidophilus LA-5 and Bifidobacterium lactis BB-12) for an 8-week period, and blood serum samples were collected before and after the intervention. Acidified milk is commonly used as a delivering vector for probiotics in commercial consumer settings. The serum samples were extracted and derivatized using N-Methyl-N-(trimethylsilyl) trifluoroacetamide (MSTFA), and GC–MS analysis was carried out. Multivariate data analysis including principal component analysis (PCA), orthogonal partial least squares-discriminant analysis (OPLS-DA), and S-plot was applied on the obtained GC–MS data, which revealed higher serum lactate, glutamine, proline creatinine/creatine, and aspartic acid levels and lower serum glucose levels after the intervention period for both treatment groups. Consequently, the present study indicated an effect of acidified milk consumption on the plasma metabolite profile, which was independent of a concomitant intake of probiotics. In addition, the present study demonstrates that GC–MS is a useful analytical technique for metabonomics studies of blood serum.