Kinetic theory of granular shear flow: Constitutive relations for the hard-disk model

A kinetic theory for the constitutive Theological relations of rapid granular shear flow of hard circular disks, characterized by a coefficient of restitutione and a surface roughness coefficient, is formulated. From a set of general constitutive equations for single-particle dynamical variables, the approximate expressions for the limit of small and large dimensionless dissipative parameterR _t are obtained. HereR _t is defined as the ratio /, where is the fluctuation of translational velocity from the mean flow velocity, is the diameter of a disk, and is the shear rate. At smallR _t the theoretical predictions can be compared with exact computer simulation results of granular dynamics that are also reported. The agreement between theory and simulation is better than expected; the present theory is accurate up to high packing density in this region ofR _t .     

Proteomic analysis of mouse liver for the evaluation of effects of Scutellariae radix by liquid chromatography with tandem mass spectrometry

Scutellariae radix or Scutellaria baicalensis is a medicinal plant that contains major flavonoids such as baicalein, baicalin, wogonin and wogonosides. The present work describes the development of an approach using proteomic analysis of mouse liver to study the effects of prolonged exposure to substances present in chemically standardized Scutellariae radix extracts. Histopathological examination of the mouse liver was compared with the proteome data. The botanical extracts were prepared using pressurized liquid extraction (PLE). A method without isotope labeling was developed, using proteolytic digestion with one- and two-dimensional liquid chromatography with tandem mass spectrometry, and was used to characterize the extent of differential protein expression in mouse liver in response to external factors such as extracts from Scutellariae radix. From the histopathological examination and proteome data, significant changes in the mouse livers were not observed for the low-dose group. The Scutellariae radix extracts at high dose were observed to cause damage at the bile duct and expression change of a number of proteins including some involved in catabolism of triglyceride-rich particles, carbohydrate metabolism, regulators of cell signaling processes, and enzymes involved in biotransformation. Thus, proteomic analysis of liver samples from mice treated with botanical extracts is a promising approach to provide information on any potential toxicity effects of the extracts. The present method also provides another means for comparing proteomes in biological samples such as liver lysates from mice subjected to different treatments.     

Corn silk induces nitric oxide synthase in murine macrophages

Corn silk has been purified as an anticoagulant previously and the active component is a polysaccharide with a molecular mass of 135 kDa. It activates murine macrophages to induce nitric oxide synthase (NOS) and generate substantial amounts of NO in time and dose-dependent manners. It was detectable first at 15 h after stimulation by corn silk, peaked at 24 h, and undetectable by 48 h. Induction of NOS is inhibited by pyrolidine dithiocarbamate (PDTC) and genistein, an inhibitor of nuclear factor kappa B (NF-kappaB) and tyrosine kinase, respectively, indicating that iNOS stimulated by corn silk is associated with tyrosine kinase and NF-kappaB signaling pathways. IkappaB-alpha degradation was detectible at 10 min, and the level was restored at 120 min after treatment of corn silk. Corn silk induced nuclear translocation of NF-kappaB by phosphorylation and degradation of IkappaB-alpha.     

Enhancement of facilitated olefin transport by amino acid in silver-polymer complex membranes

Silver ions dissolved in a polymer matrix are additionally coordinated by carbonyl oxygens of asparagines and their counter anions interact with cationic sites, resulting in the enhanced activity of the silver ion as an olefin carrier for facilitated olefin transport.     

Solvent effects in the free radical copolymerization of vinyl acetate and methyl methacrylate

A study was made of the effects of five solvents on the compositions of copolymers of vinyl acetate (VA) and methyl methacrylate (MMA) produced by free radical polymerization from feeds rich in VA. The MMA content was reduced significantly by propanol, unaffected by benzene and ethyl acetate and increased by acetonitrile and acetone. The effects observed for propanol, acetonitrile and acetone all reached a maximum at a solvent to monomer molar ratio of about 7:1. Experiments showed that neither monomer physical aggregation nor monomer carbonyl polarization phenomena could explain completely the observed effects. A complete explanation probably requires several factors including some associated with polymer radical reactivity.     

A new and convenient synthesis of N-substituted perhydroazepines from adipaldehyde and primary amines with tetracarbonylhydridoferrate,HFe(CO), as a selective reducing agent

Ethanolic tetracarbonylhydridoferrate combined with adipaldehyde is very efficient for the selective transformation of an amino group into perhydroazepine. A large variety of both aliphatic and aromatic amines react with adipaldehyde in the presence of tetracarbonylhydridoferrate at room temperature and carbon monoxide to give the corresponding N-alkyl- and N-arylperhydroazepines in good to excellent yields.     

High-resolution NMR spectroscopy of membrane proteins in aligned bicelles

High-resolution solid-state NMR spectra can be obtained from uniformly (15)N-labeled membrane proteins in magnetically aligned bicelles. Fast uniaxial diffusion about the axis of the bilayer normal results in single-line spectra that contain the orientational information necessary for protein structure determination.     

Synthesis and structure of the cluster ion pair [Ru3(CO)9[mu-P(NPri2)2]3][Ru6(CO)15(mu 6-C)[mu-P(NPri2)2]]. A theoretical overview of M3(mu-PR2)3 frameworks

The compound [Ru3(CO)9[mu-P(NPri2)2]3][Ru6(CO)15(mu 6-C)[mu-P(NPri2)2]] (1), obtained via the addition of PCl(NPri2)2 to K2[Ru4(CO)13], crystallizes in the monoclinic space group P2l/c with a = 15.537(8) A, b = 36.151(16) A, c = 19.407(5) A, beta = 91.14(2) degrees, Z = 4, and R = 0.069 for 8006 observed reflections. The unit cell is unusual in that it contains both a typical octahedral Ru6 cluster anion (1a), featuring an encapsulated carbide, and a symmetrical phosphido bridge, in addition to a 50-electron trinuclear cluster cation [Ru3(CO)9[mu-P(NPri2)2]3]+ (1c). The latter, with approximate D3h symmetry, exhibits long Ru-Ru distances (> or = 3.15 A). Among the family of clusters with M3(mu-PR2)3 cores and different numbers of both electrons (TEC) and terminal ligands (LxLyLz), 1c is unique in that it is a 333 stereotype with 50 valence electrons. MO calculations permit us to predict the existence of redox congeners of 1c clusters and related 48e Re3 clusters. This work also presents a summary of the relationships between the electronic and the geometric structures for all known M3LxLyLz(mu-PR2)3 species. The basic stereochemical features are influenced by the total-electron count and, hence, by the degree of M-M bonding, as well as the remarkable flexibility of the phosphido bridging ligands. The mu-PR2 ligands need not necessarily lie in the M3 plane, and a wide range of M-P-M angles (as small as 72 degrees or as large as 133 degrees) have been observed.     

The effect of the bridge group on the thermal stability of nitro-substituted aromatic polyamides

The effect of introducing a bridge group into the diamine moiety on the thermal stability of aromatic polyamides substituted with nitro group in the diamine ring at the ortho position to the amide group was studied. Our present work showed that the bridge group, whether it was electron withdrawing or releasing, did not have a significant effect on the activity of the nitro group for the intramolecular cyclization reaction to poly(benzoxazole)s.