BP

About: BP is a company organization based out in London, United Kingdom. It is known for research contribution in the topics: Catalysis & Nickel. The organization has 3846 authors who have published 3676 publications receiving 65552 citations. The organization is also known as: BP plc, & British Petroleum.

Pore size distribution analysis of microporous carbons: a density functional theory approach

Abstract: We present an improved method, based upon density functional theory, for the determination of the pore size distribution (PSD) of porous sorbents. The adsorption isotherms predicted by nonlocal mean field theory for individual slit pores are correlated as a function of pressure and pore width. The PSD is then calculated by fitting this correlation to the experimental adsorption isotherm of the sorbent. We apply the analysis method to adsorption data for nitrogen on several porous carbons. In this application, the porous network is modeled as a continuous size distribution of noninteracting slit-shaped graphitic pores. The PSDs obtained by using the Kelvin equation and using the local and nonlocal versions of the mean field density functional theory are compared and evaluated. The results demonstrate that nonlocal theory provides a more accurate interpretation of the PSD than previous methods have achieved, particularly when the analysis is applied to highly microporous sorbents.

Oxygen isotope calibration of the onset of ice-rafting and history of glaciation in the North Atlantic region

Abstract: We report here that DSDP Site 552A, cored with the hydraulic piston corer on the west flank of Rockall Bank, recovered an undisturbed sequence of alternating white deep-sea carbonate oozes and dark-coloured layers that are rich in glacial debris. Oxygen isotope analysis of the sequence together with detailed nannofossil and palaeomagnetic stratigraphy shows that the first major horizon of ice-rafting occurred at about 2.4 Myr, and was preceded by a minor pulse of ice-rafting at about 2.5 Myr. The carbon isotope record shows that the site has been bathed by a water mass of similar characteristics to present-day North Atlantic deep water at least since 3.5 Myr.

Intrinsic stress in sputter-deposited thin films

Abstract: A review of the sputtered film stress literature shows that the intrinsic stress can be tensile or compressive depending on the energetics of the deposition process. Modeling studies of film growth and extensive experimental evidence show a direct link between the energetics of the deposition process and film microstructure, which in turn determines the nature and magnitude of the stress. The fundamental quantities are the particle flux and energy striking the condensing film, which are a function of many process parameters such as pressure (discharge voltage), target/sputtering gas mass ratio, cathode shape, bias voltage, and substrate orientation. Tensile stress is generally observed in zone 1-type, porous films and is explained in terms of the grain boundary relaxation model, whereas compressive stress, observed in zone T-type, dense films, is interpreted in terms of the atomic peening mechanism. Modeling of the atomic peening mechanism and experimental data indicate that the normalized moment...

Engineered Saccharomyces cerevisiae capable of simultaneous cellobiose and xylose fermentation.

Abstract: The use of plant biomass for biofuel production will require efficient utilization of the sugars in lignocellulose, primarily glucose and xylose. However, strains of Saccharomyces cerevisiae presently used in bioethanol production ferment glucose but not xylose. Yeasts engineered to ferment xylose do so slowly, and cannot utilize xylose until glucose is completely consumed. To overcome these bottlenecks, we engineered yeasts to coferment mixtures of xylose and cellobiose. In these yeast strains, hydrolysis of cellobiose takes place inside yeast cells through the action of an intracellular β-glucosidase following import by a high-affinity cellodextrin transporter. Intracellular hydrolysis of cellobiose minimizes glucose repression of xylose fermentation allowing coconsumption of cellobiose and xylose. The resulting yeast strains, cofermented cellobiose and xylose simultaneously and exhibited improved ethanol yield when compared to fermentation with either cellobiose or xylose as sole carbon sources. We also observed improved yields and productivities from cofermentation experiments performed with simulated cellulosic hydrolyzates, suggesting this is a promising cofermentation strategy for cellulosic biofuel production. The successful integration of cellobiose and xylose fermentation pathways in yeast is a critical step towards enabling economic biofuel production.