Surface structure of MgO(001) surface studied by LEED

MgO(001) surfaces prepared by three different heat treatments were studied by LEED. The first was the surface just after the vacuum cleavage; the second was that after the annealing of the first one at 300°C in UHV. The third was prepared by cleaving in air and heating in oxygen until the carbon Auger peak disappear. LEED I-V curves of the diffraction spots, (10), (11) and (20), were recorded and compared carefully. No remarkable difference corresponding to the preparing methods was found. Therefore, the atomic structures of the surfaces seem to be similar to each other. These experimental I-V curves were compared with the theoretical curves obtained by dynamical calculations for several grades of surface relaxation. The theoretical curves with no relaxation or with the smallest one in the calculation (2.5% expand) fitted best with the experimental curves. The experimental curves were also compared with the theoretical ones calculated for the rumpled surface. But no effect induced by the rumpling was found in the experimental curves.     

CONFIGURATIONS OF NEUROSPORENE ISOMERS ISOLATED FROM THE REACTION CENTER AND THE LIGHT-HARVESTING COMPLEX OF Rhodobacter spheroides G1C. A RESONANCE RAMAN, ELECTRONIC ABSORPTION, AND 1H-NMR STUDY

Abstract— HPLC analysis of neurosporene extracted from the chromatophore membranes of Rhodobacter spheroides G1C showed two isomeric components 1 and 2. Extract from the light-harvesting complex (LH) gave only component 2, while extract from the reaction center (RC) mainly gave component 1. Both components were isolated, and their configurations were determined by means of (1) resonance Raman, (2) electronic absorption, and (3) ¹H-HMR spectroscopy. The configuration of component 2 originating from LH was determined to be all -trans and that of component 1 from RC was determined to be 15- cis . Thus, our previous configurational prediction of this particular carotenoid bound to RC, by means of resonance Raman spectroscopy, to be 15-cis [Y. Koyama, T. Takii, K. Saiki and K. Tsukida, Photobiochem. Photobiophys. 5 (1983)139–150] is confirmed.     

CONFIGURATIONS OF CAROTENOIDS IN THE REACTION CENTER and THE LIGHT-HARVESTING COMPLEX OF Rhodospirillum rubrum. NATURAL SELECTION OF CAROTENOID CONFIGURATIONS BY PIGMENT PROTEIN COMPLEXES

Abstract— Carotenoids extracted from the reaction center (RC), the light-harvesting complex (LH), and the chromatophore membrane of Rhodospirillum rubrum SI were analyzed by high-performance liquid chromatography. The chemical structures and the configurations of major components were determined by means of mass, Raman, electronic absorption and ¹H-NMR spectroscopy. The results indicated: (1) 15- cis -spirilloxanthin is bound to RC; (2) both all-frans-spirilloxanthin and aII-(ran.s-3,4-dihydrospirilloxanthin are bound to LH and (3) 13-cK-spirilloxanthin is additionally present in the chromatophore membrane. The natural selection of the carotenoid configurations, i.e. 15-ris by RC and aW-trans by LH, is discussed in relation to the physiological functions and the photophysical properties of isomeric carotenoids.     

Determination of elements in bovine tissues by instrumental neutron activation analysis

Instrumental neutron activation analysis was carried out to obtain the normal concentration of trace elements in bovine tissues (heart, liver, kidney, spleen, lymph nodes) and serum. Concentrations of 17 elements were determined. In this paper, concentrations of Al, Br, Cs, In and Rb are given and correlations of concentrations are discussed between Cl and Br and between K and Cs or Rb. Significant positive correlations have been found between Cl and Br concentrations in all tissues, between K and Cs concentrations in tissues excluding kidney, and between K and Rb concentrations in tissues excluding liver.     

Low-intensity pulsed ultrasound (LIPUS) and cell-to-cell communication in bone marrow stromal cells

Low-intensity pulsed ultrasound (LIPUS) is an established therapy for fracture repair and has been used widely in the clinics, but its underlying mechanism of action remains unclear. The aim of the current research was to determine the effect of LIPUS on gap junctional cell-to-cell intercellular communication in rat bone marrow stromal cells (BMSC) in vitro and to determine whether the ability of BMSCs to communicate by gap junctions would affect their response to LIPUS. Single or daily-multiple LIPUS treatment at 1.5 MHz, 30 mW/cm², for 20 min was applied to BMSC. We demonstrated that BMSC form functional gap junctions and single LIPUS treatment significantly increased the intracellular dye transfer between BMSC. In addition, activated phosphorylation of ERK1/2 and p38 by LIPUS stimulation was diminished when cells were treated with a gap junction inhibitor 18β-glycyrrhetinic acid (18β). We further demonstrated that 18β diminished the significant increase in alkaline phosphatase activity following LIPUS stimulation. These results suggest a potential role of gap junctional cell-to-cell intercellular communication on the effects of LIPUS in BMSC.