98 resultados para CC BOND
Resumo:
This paper tests empirically whether pension information derived by corporate pension accounting disclosures is priced in corporate bond spreads. The model represents a hybrid of more traditional accounting ratio-based models of credit risk and structural models of bond spreads initiated by Merton (1974). The model is fitted to 5 years of data from 2002 to 2006 featuring companies from the US and Europe. The paper finds that while unfunded pension liabilities are priced in the overall sample, they are not priced as aggressively as traditional leverage. Furthermore, an extended model shows that the pension–credit risk relation is most evident in the US and Germany, where unfunded pension liabilities are priced more aggressively than traditional forms of leverage. No pension–credit risk relation is found in the other countries sampled, notably the UK, Netherlands and France.
Resumo:
A novel, inducible, carbon-phosphorus bond-cleavage enzyme, phosphonoacetate hydrolase, was purified from cells of Pseudomonas fluorescens 23F grown phosphonoacetate. The native enzyme had a molecular mass of approximately 80 kDa and, upon SDS/PAGE, yielded a homogenous protein band with an apparent molecular mass of about 38 kDa. Activity of purified phosphonoacetate hydrolase was Zn2+ dependent and showed pH and temperature optima of approximately 7.8 and 37 degrees C, respectively. The purified enzyme had an apparent K-m of 1.25 mM for its sole substrate phosphonoacetate, and was inhibited by the structural analogues 3-phosphonopropionate and phosphonoformate. The NH2-terminal sequence of the first 19 amino acids displayed no significant similarity to other databank sequences.
Resumo:
A replica plate screening technique, based on the acid molybdate assay for detection of phosphate has been developed to permit the detection of microorganisms capable of mineralizing organophosphonates. The method was further adapted as the basis of an activity stain for the detection of the carbon - phosphorus bond cleavage enzyme phosphonoacetate hydrolase in PAGE gels.
Resumo:
The selective hydrogenation of ,-unsaturated aldehydes and ketones has been studied using ketoisophorone and cinnamaldehyde as model substrates using manganese oxide octahedral molecular sieve (OMS-2) based catalysts. For the first time, OMS-2 has been shown to be an efficient and selective hydrogenation catalyst. High selectivities for either the CC or CO double bond at approximate to 100% conversion were achieved by using OMS-2 and platinum supported on OMS-2 catalysts. Density functional theory (DFT) calculations showed that the dissociation of H2 on OMS-2 was water assisted and occurred on the surface Mn of OMS-2(001) that had been modified by an adsorbed H2O molecule. The theoretically calculated activation barrier was in good agreement with the experimentally determined value for the hydrogenation reactions, indicating that H2 dissociation on OMS-2 is likely to be the rate-determining step. A significant increase in the rate of reaction was observed in the presence of Pt as a result of the enhancement of H2 dissociative adsorption and subsequent reaction on the Pt or spillover of the hydrogen to the OMS-2 support. The relative adsorption strengths of ketoisophorone and cinnamaldehyde on the OMS-2 support compared with the Pt were found to determine the product selectivity.
Resumo:
This article uses the personal ledgers of a cinema manager to explore programming and film exhibition at the Southampton Odeon in the 1970s. The detailed accounts provide a rare insight into cinema exhibition and challenge the notion that 1970s cinema was all about sex, violence, horror and exploitation, suggesting instead that audiences at this cinema, favoured very different fare.
Resumo:
We have performed density functional theory (DFT) calculations to investigate the reaction mechanism of the cleavage of the carbonyl bond in amides on both flat and stepped Ru surfaces. The simplest amide molecule, N,N-dimethylacetamide (DMA), was used as the exemplar model molecule. Through the calculations, the most stable transition states (TSs) in all the pathways on both flat and stepped Ru surfaces are identified. Comparing the energy profiles of different reaction pathways, we find that a direct cleavage mechanism is always energetically favored as compared with an alternative hydrogen-induced mechanism on either the flat or stepped Ru surface. It is easier for the dissociation process to occur on the stepped surface than on the flat surface. However, as compared with the terrace, the superiority of step sites boosting the C-O bond dissociation is not as evident as that on CO dissociation.