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The progress toward a commercial solid oxide fuel cell ͑SOFC͒ continues to be a slow struggle due to materials, stacking, and system challenges. One long-term challenge has been the search for suitable cathode materials for use on intermediate ͑650-800°C͒ yttria-stabilized zirconia ͑YSZ͒ electrolytes and low-temperature ͑500-650°C͒ gadolinia-doped ceria ͑CGO͒ electrolytes. The present study has identified La͑Sr͒FeO 3 and possibly Pr͑Sr͒FeO 3 as potential cathode materials for YSZ. A La-deficient La͑Sr͒FeO 3 cathode has achieved an area-specific resistance of 0.1 ⍀ cm 2 at 800°C, with stable long-term performance. On CGO, Pr͑Sr͒CoO 3 , Gd͑Sr͒CoO 3 , and Sr͑Co/Fe) 1.5 O 3.25 have all achieved an area-specific resistance close to 0.1 ⍀ cm 2 at 650°C, with relatively stable long-term performance, but further reduction in temperature to 600°C is necessary for efficient CGO operation.

The hepatitis E virus (HEV) is the causative agent of hepatitis E, an acute form of viral hepatitis. The biology and pathogenesis of HEV remain poorly understood. We have used in vitro binding assays to show that the HEV ORF3 protein (pORF3) binds to a number of cellular signal transduction pathway proteins. This includes the protein tyrosine kinases Src, Hck, and Fyn, the p85␣ regulatory subunit of phosphatidylinositol 3-kinase, phospholipase C␥, and the adaptor protein Grb2. A yeast two-hybrid assay was used to further confirm the pORF3-Grb2 interaction. The binding involves a proline-rich region in pORF3 and the src homology 3 (SH3) domains in the cellular proteins. Competition assays and computer-assisted modeling was used to evaluate the binding surfaces and interaction energies of the pORF3⅐SH3 complex. In pORF3-expressing cells, pp60 src was found to associate with an 80-kDa protein, but no activation of the Src kinase was observed in these cells. However, there was increased activity and nuclear localization of ERK in the pORF3-expressing cells. These studies suggest that pORF3 is a viral regulatory protein involved in the modulation of cell signaling. The ORF3 protein of HEV appears to be the first example of a SH3 domain-binding protein encoded by a virus that causes an acute and primarily self-limited infection.Hepatitis E virus (HEV), 1 the causative agent for hepatitis E, is a waterborne pathogen endemic to much of the developing world where it causes rampant sporadic infections and large scale epidemics (1-4). While the infection is self-limited with no associated chronicity, a fraction of the patients progress to fulminant hepatitis (5, 6), the most severe form of acute hepatitis. High mortality rates of 20 -30% reported for HEV infection during pregnancy (7,8) are also the result of fulminant hepatitis. The reasons for this and the mechanisms of viral pathogenesis are not known. The studies on HEV biology and pathogenesis have been severely restricted by the lack of a reliable cell culture system and small animal models of viral infection. We have used subgenomic expression strategies to study the properties and functions of individual HEV gene products toward understanding viral replication and pathogenicity (9 -12).The HEV genome is a ϳ7.5-kilobase polyadenylated, positive-sense RNA that contains three open reading frames (ORFs) designated ORF1, ORF2, and ORF3 (13). The ORF3 of HEV encodes a protein of ϳ13.5 kDa, called pORF3, for which no function has been assigned. When expressed in animal cells, pORF3 is phosphorylated at a single serine residue (Ser 80 ) in its 123-amino acid primary sequence (11). In vitro phosphorylation experiments suggested that pORF3 may be a substrate for the mitogen-activated protein (MAP) kinase, and subcellular fractionation revealed its association with the cytoskeleton (11). Recent results using inhibitors, activators, and dominant negative alleles show that pORF3 is a substrate for the extracellular signal-regulated kinase (ERK) as well as the stressactivated pr...

The hepatitis B virus X protein (HBx) sequence (154 aa) has been divided into six regions (A-F) based on its sequence homology with X proteins of other mammalian hepadnaviruses. Regions A, C, and E are more conserved and include all the four conserved cysteines (C7, C61, C69, and C137).To localize the regions of HBx important for transactivation, a panel of 10 deletion mutants (X5-X14) and 4 single point mutants (X1-X4), each corresponding to a conserved cysteine residue, was constructed by site-directed mutagenesis. A HBxspecific monoclonal antibody was developed and used to confirm the expression of mutants by Western blot. Transactivation property of the HBx mutants was studied on Rous sarcoma virus-long terminal repeat (RSV-LTR) in transient transfection assays. We observed that deletion of the most conserved region A or substitution of the N-terminal cysteine (C7) had no effect on transactivation. Deletion ofthe nonconserved regions B or F also had no deleterious effects. Deletions of regions C and D resulted in a significant loss of function. Substitution of both C6' and C69 present in region C, caused almost 90%0o loss of activity that could be partially overcome by transfecting more expression plasmid. The fully conserved 9 amino acid segment (residues 132 to 140)within region E including C137 appeared to be crucial for its activity. Finally, a truncated mutant X15 incorporating only regions C to E (amino acids 58-140) was able to stimulate the RSV-LTR quite efficiently, suggesting a crucial role played by this domain in transactivation function.Hepatitis B virus (HBV) is the infective agent for the widespread liver disease in humans known as hepatitis B. Chronic infection has been associated with a high risk for development of hepatocellular carcinoma (1, 2). Similar viruses are also found in several animal species such as woodchucks, ground squirrels, and ducks, and together they constitute the family Hepadnaviridae. The small 3.2-kb DNA genome of HBV has at least four open reading frames called S, C, P, and X. During the natural course of HBV infection, the X gene expresses a polypeptide (HBx) of 154 residues that is implicated in HBVmediated hepatocellular carcinoma (3, 4).HBx is a pleiotropic transactivator because it can stimulate the cis-elements of not only the HBV genome (5, 6) but also of a wide range of other viral promoters such as simian virus 40 early (5, 7, 8) and herpes simplex virus-tk (7, 8), and long terminal repeats (LTRs) of human immunodeficiency virus type 1 (9, 10), human immunodeficiency virus type 2 (11), human T-lymphotropic virus type 1 (7), mouse mammary tumor virus (5, 7), and Rous sarcoma virus (RSV) (7,8). HBx can also upregulate the expression of some protooncogenes like c-myc (12) and c-fos/c-jun (13)(14)(15) MATERIALS AND METHODSHBx Expression Vector and HBx Mutants. The HBx gene was amplified as a 481-bp DNA fragment by PCR using the full-length HBV template (adw subtype) (38) and the following oligonucleotide primers: forward, 5'-CGGAATTCATGGCT-GCTAGGCTGT-...

A series of Vulcan carbon-supported Pd-Cu catalysts with various molar ratios of Pd to Cu was prepared by co-impregnation followed by a reduction in a hydrogen atmosphere at three different temperatures. The degree of alloying between the two metals, alloy composition, and particle size and size distribution were characterized by X-ray diffraction, transmission electron microscopy, and energy-dispersive X-ray spectroscopy. The electrocatalytic activity for the oxygen reduction reaction ͑ORR͒ for these various compositions was determined using the thin-film rotating disk electrode technique. Our study reveals that the Pd-Cu bimetallic electrocatalysts, with a suitable degree of alloying, offer a greatly enhanced ORR activity compared to the Pd monometallic electrocatalyst. The best electrocatalytic activities were observed for the bimetallic catalysts that showed alloy nanoparticles with a Pd-Cu molar ratio of approximately 1:1.