Search

For integer k ≥ 2 and prime power q , Lazebnik and Ustimenko (1995) proposed an algebraic bipartite graph D ( k , q ) which is q -regular, edge-transitive and of large girth. Füredi et al. (1995) conjectured that D ( k , q ) has girth k + 5 for all odd k and all q ≥ 4 and, shown that this conjecture is true for the case that ( k + 5 ) / 2 divides q − 1 . Cheng et al. (2014) shown that this conjecture is true for the case that ( k + 5 ) / 2 is an arbitrary power of the characteristic of F q . In this paper, we propose a generalization for the binomial coefficients and show that this conjecture is true when ( k + 5 ) / 2 is the product of an arbitrary factor of q − 1 and an arbitrary power of the characteristic of F q . [ABSTRACT FROM AUTHOR]

For integer k ≥ 2 and prime power q , an algebraic bipartite graph D ( k , q ) of girth at least k + 4 was introduced by Lazebnik and Ustimenko (1995). Füredi et al. (1995) shown that the girth of D ( k , q ) is equal to k + 5 if k is odd and q is a prime power of form 1 + n ( k + 5 ) / 2 and, conjectured further that D ( k , q ) has girth k + 5 for all odd k and all q ≥ 4 . In this paper, we show that this conjecture is true when ( k + 5 ) / 2 is a power of the characteristic of F q . [ABSTRACT FROM AUTHOR]

Abstract: Cobalt nanowires with transverse magnetocrystalline anisotropy have been fabricated and the dynamic permittivity and permeability spectra of the nanowire/paraffin composite were measured in the frequency range of 0.5–18GHz. The imaginary part of the permeability spectra for the nanowire/paraffin composite samples exhibits a strong absorption peak at 6.1GHz and two minor peaks at above 10GHz. It is determined that the peak at 6.1GHz is attributed to the natural resonance mechanism and the other two peaks are caused by eddy current effect. The permeability spectra attributed to natural resonance are fitted using the LLG equation and further confirmed by calculation based on the Kittel formula. The electromagnetic wave reflection loss values of the nanowire/paraffin composite sample are lower than −20dB when the thickness of the nanowire/paraffin composite is adjusted, suggesting that the cobalt nanowire composites are promising candidates as microwave absorbers. [Copyright &y& Elsevier]

Elevated circulating free fatty acid (FFA) level is closely linked to the pathogenesis of insulin resistance and type 2 diabetes mellitus. Activation of the adenosine A 1 receptor (A 1 R) inhibits lipolysis in adipocytes and hence reduces the concentration of FFA, which represents a potential target for the development of antilipolytic agents. We aimed to assess the binding affinity as well as target binding kinetics of A 1 R agonists and further delineate a possible relationship with their antilipolytic effect in adipocytes. Radioligand binding assays were performed to determine the affinity and kinetics of three representative A 1 R agonists, namely CPA, LUF6944 and LUF6941, on the rat A 1 R. Functional responses to these agonists were examined in both a recombinant cell system and physiologically relevant rat adipocytes. The three A 1 R agonists displayed similar affinity while divergent target binding kinetics on the rat A 1 R. Irrespective of equilibrium binding affinity, temporal analysis of receptor signaling demonstrated persistent functional responses for the long residence time agonist, despite removal of excess agonist, in both a recombinant cell system and in rat adipocytes. By contrast, such effect was less pronounced or even lost for agonists with medium or short receptor residence time, respectively. Our results indicate that ligand receptor binding kinetics rather than their affinity or potency play an essential role in regulating cellular responses. The long residence time A 1 R agonist produces a sustained wash-resistant antilipolytic effect in rat adipocytes and thus may represent a potential antilipolytic alternative for further investigation. [ABSTRACT FROM AUTHOR]

Myasthenia gravis (MG) is an autoimmune disorder of the neuromuscular junction (NMJ). Most cases of MG are caused by autoantibodies against the acetylcholine receptor (AChR), muscle-specific kinase (MuSK) and low-density lipoprotein receptor-related protein 4 (LRP4). Recent studies have identified anti-agrin antibodies in MG patients lacking these three antibodies (i.e., triple negative MG). Agrin is a basal lamina protein that has two isoforms. Neural agrin (N-agrin) binds to LRP4 to activate MuSK to induce AChR clusters and is thus critical for NMJ formation. We demonstrate that mice immunized with N-agrin showed MG-associated symptoms including muscle weakness, fragmented and distorted NMJs. These effects were not observed in mice injected with muscle agrin (M-agrin), an isoform that is inactive in inducing AChR clusters. Treatment with anti-N-agrin, but not anti-M-agrin, antibodies reduced agrin-induced AChR clusters in muscle cells. Together, these observations suggest that agrin antibodies may be play a role in MG pathogenesis. [ABSTRACT FROM AUTHOR]

Quinone methide (QM) formation induced by endogenously generated H 2 O 2 is attractive for biological and biomedical applications. To overcome current limitations due to low biological activity of H 2 O 2 -activated QM precursors, we are introducing herein several new arylboronates with electron donating substituents at different positions of benzene ring and/or different neutral leaving groups. The reaction rate of the arylboronate esters with H 2 O 2 and subsequent bisquinone methides formation and DNA cross-linking was accelerated with the application of Br as a leaving group instead of acetoxy groups. Additionally, a donating group placed meta to the nascent exo-methylene group of the quinone methide greatly improves H 2 O 2 -induced DNA interstrand cross-link formation as well as enhances the cellular activity. Multiple donating groups decrease the stability and DNA cross-linking capability, which lead to low cellular activity. A cell-based screen demonstrated that compounds 2a and 5a with a OMe or OH group dramatically inhibited the growth of various tissue-derived cancer cells while normal cells were less affected. Induction of H2AX phosphorylation by these compounds in CLL lymphocytes provide evidence for a correlation between cell death and DNA damage. The compounds presented herein showed potent anticancer activities and selectivity, which represent a novel scaffold for anticancer drug development. [ABSTRACT FROM AUTHOR]