Transglobal Evidentialism-Reliabilism

We propose an approach to epistemic justification that incorporates elements of both reliabilism and evidentialism, while also transforming these elements in significant ways. After briefly describing and motivating the non-standard version of reliabilism that Henderson and Horgan call “transglobal” reliabilism, we harness some of Henderson and Horgan’s conceptual machinery to provide a non-reliabilist account of propositional justification (i.e., evidential support). We then invoke this account, together with the notion of a transglobally reliable belief-forming process, to give an account of doxastic justification.

Test of the Duh-Haymet-Henderson theory for mixtures: cavity correlation functions and excess volumes

The accuracy of the Duh-Haymet-Henderson (DHH) integral equation theory for predicting the cavity correlation functions of mixtures has been tested by comparison with molecular simulations. We have compared the cavity correlation functions, internal energies, and pressures computed for Lennard-Jones model mixtures of Ar/Kr, Ar/Ne, and Ar/Xe with these same quantities computed from the DHH theory and also, for reference, the Percus-Yevick (PY) integral equation theory. We found that DHH gave much better accuracy than PY at high densities. At low densities DHH and PY give essentially identical predictions. We have computed excess volumes for Ar/Kr mixtures at two pressures (10 and 20?MPa) at 132.32?K, for which experimentally derived data are available. The DHH theory predicts the correct trends and is quantitatively more accurate than the PY theory for predicting the excess volumes. We have tested the local optimality of the DHH theory for pure fluids by adding two adjustable parameters to the DHH bridge function expression to see if it is possible to improve the DHH predictions of the cavity correlation function empirically, holding the form of the bridge function constant. We found that no single set of adjustable parameter values could improve the accuracy of DHH over multiple different isotherms. Furthermore, perturbing DHH leads to a decrease in accuracy of the predictions of both the pressure and energy, although small improvements in the cavity correlation functions were achieved. Thus, the DHH theory is locally optimal, given the form of the bridge function.     

Separation of intact pyruvate dehydrogenase complex using blue native agarose gel electrophoresis

We show that the blue native gel polyacrylamide electrophoresis system (BN-PAGE) can be applied to pyruvate dehydrogenase complex (PDC). BN-PAGE has been used extensively to study the multisubunit enzymes of oxidative phosphorylation, as nondenaturing separation in the first dimension maintains holoenzyme integrity. However, the standard protocol was inappropriate for PDC as, at 10 MDa, it is approximately ten times larger than the largest respiratory chain enzyme complex. Therefore, agarose was substituted for polyacrylamide. Moreover, a substantial decrease in salt concentration was necessary to prevent dissociation of PDC. As with standard BN-PAGE, immunoblots of second-dimensional sodium dodecyl sulfate-PAGE (SDS-PAGE) provided more detailed information on specific subunits and subcomplexes. The method was applied to human heart mitochondrial fragments, control cultured human cells, rho0 cells that lack mitochondrial DNA, and two cell lines derived from patients with PDC deficiency. The PDC deficient cell lines showed a clear correlation between amount of PDC holoenzyme and disease severity. In cells lacking mitochondrial DNA, synthesis and assembly of all PDC subunits (all nuclearly encoded) appeared normal, suggesting that respiratory function has no regulatory role in PDC biogenesis. Blue native agarose gel electrophoresis coupled with standard second-dimensional SDS-PAGE provides a new tool to be used in conjunction with biochemical assays and immunoblots of one-dimensional SDS-PAGE to further elucidate the nature of PDC in normal and disease states. Furthermore, other cellular protein complexes of 1 MDa or more can be analysed by this method.     

Key Word Index for Volume 11

Other Index

Key Word Index for Volume 11     

Physical and electrochemical properties of N-alkyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide ionic liquids: PY13FSI and PY14FSI

Two ionic liquids based upon N-alkyl-N-methylpyrrolidinium cations (PY(1R)(+)) (R=3 for propyl or 4 for butyl) and the bis(fluorosulfonyl)imide (FSI(-)), N(SO2F)2(-), anion have been extensively characterized. The ionic conductivity and viscosity of these materials are found to be among the highest and lowest, respectively, reported for aprotic ionic liquids. Both ionic liquids crystallize readily on cooling and undergo several solid-solid phase transitions on heating prior to melting. PY13FSI and PY14FSI are found to melt at -9 and -18 degrees C, respectively. The thermal stability of PY13FSI and PY14FSI is notably lower than for the analogous salts with the bis(trifluoromethanesulfonyl)imide (TFSI(-)), N(SO2CF3)2(-), anion. Both ionic liquids have a relatively wide electrochemical stability window of approximately 5 V.     

Acetone and water on TiO2(110): H/D exchange

Isotopic H/D exchange between coadsorbed acetone and water on the TiO2(110) surface was examined using temperature programmed desorption (TPD) as a function of coverage and two surface pretreatments (O2 oxidation and mild vacuum reduction). Coadsorbed acetone and water interact repulsively on reduced TiO2(110) on the basis of results from the companion paper to this study, with water exerting a greater influence in destabilizing acetone and acetone having only a nominal influence on water. Despite the repulsive interaction between these coadsorbates, about 0.02 monolayers (ML) of a 1 ML d6-acetone on the reduced surface (vacuum annealed at 850 K to a surface oxygen vacancy population of 7%) exhibits H/D exchange with coadsorbed water, with the exchange occurring exclusively in the high-temperature region of the d6-acetone TPD spectrum at approximately 340 K. The effect was confirmed with combinations of d0-acetone and D2O. The extent of exchange decreased on the reduced surface for water coverages above approximately 0.3 ML due to the ability of water to displace coadsorbed acetone from first layer sites to the multilayer. In contrast, the extent of exchange increased by a factor of 3 when surface oxygen vacancies were pre-oxidized with O2 prior to coadsorption. In this case, there was no evidence for the negative influence of high water coverages on the extent of H/D exchange. Comparison of the TPD spectra from the exchange products (either d1- or d5-acetone depending on the coadsorption pairing) suggests that, in addition to the 340 K exchange process seen on the reduced surface, a second exchange process was observed on the oxidized surface at approximately 390 K. In both cases (oxidized and reduced), desorption of the H/D exchange products appeared to be reaction limited and to involve the influence of OH/OD groups (or water formed during recombinative desorption of OH/OD groups) instead of molecularly adsorbed water. The 340 K exchange process is assigned to reaction at step sites, and the 390 K exchange process is attributed to the influence of oxygen adatoms deposited during surface oxidation. The H/D exchange mechanism likely involves an enolate or propenol surface intermediate formed transiently during the desorption of oxygen-stabilized acetone molecules.     

Defining topological features of membrane proteins by nanoelectrospray ionisation mass spectrometry

The D‐galactose‐H⁺ symport protein, GalP, of Escherichia coli is the bacterial homologue of the human glucose transport protein, GLUT1. Here we demonstrate that mass spectrometry can be used to map modification by covalently bound reagents, and also to detect structural changes in the GalP protein that occur upon substrate binding. The small thiol‐group‐specific reagent N‐ethylmaleimide (NEM) was used to modify the cysteine residues in GalP(His)₆ both alone and in the presence of D‐glucose, a known substrate. Employing a mixture of proteolysis and thermal degradation methods, the three cysteine residues were found to undergo sequential reactions with NEM, with Cys374 being modified first, followed by Cys389 and finally Cys19, thus indicating their different accessibilities within the three‐dimensional structure of the protein. Prior binding of the substrate D‐glucose to the protein protected Cys19 and Cys374 against NEM modification, but not Cys389. Cys374 had been expected to be shielded by D‐glucose binding while Cys389 had been expected to be unaffected, consistent with their proposed respective locations in the vicinity of, and distant from, the sugar binding site. However, the inaccessibility of Cys19 was unexpected and suggests a structural change in the protein promoted by D‐glucose binding which changes the proximity of Cys19 with respect to the D‐glucose‐binding site. Copyright © 2010 John Wiley & Sons, Ltd.     

A rapid heating and high magnetic field thermal analysis technique

Journal of Thermal Analysis and Calorimetry - A new thermal analysis technique is described that allows measurements to be performed on bulk samples at extreme heating and cooling rates and in high...     

A redox-mediator pathway for enhanced multi-colour electrochemiluminescence in aqueous solution

The classic and most widely used co-reactant electrochemiluminescence (ECL) reaction of tris(2,2′-bipyridine)ruthenium(ii) ([Ru(bpy)₃]²⁺) and tri-n-propylamine is enhanced by an order of magnitude by fac-[Ir(sppy)₃]³⁻ (where sppy = 5′-sulfo-2-phenylpyridinato-C²,N), through a novel ‘redox mediator’ pathway. Moreover, the concomitant green emission of [Ir(sppy)₃]³⁻* enables internal standardisation of the co-reactant ECL of [Ru(bpy)₃]²⁺. This can be applied using a digital camera as the photodetector by exploiting the ratio of R and B values of the RGB colour data, providing superior sensitivity and precision for the development of low-cost, portable ECL-based analytical devices.

A water-soluble Ir(iii) complex is shown to enhance the ‘remote’ mechanism of the most widely used co-reactant ECL reaction of tris(2,2′-bipyridine)ruthenium(ii) with tripropylamine.