Proper composition for superconductivity in Pb(Ba, Sr)2(Y, Ca)Cu3O7

Superconductivity and composition analysis of PbBaSr(Y, Ca)Cu₃O_y with fixed ratio of Sr/Ba = 1 were studied. Synthesis condition and superconductivity of Pb(Ba, Sr)₂(Y, Ca)Cu₃O_y with various ratio of Sr/Ba and Ca/Y were also studied. It was found that T_c increased with increasing Ca concentration, and that Sr-rich specimens allowed to contain more Ca. PbBa_0.8Sr_1.2Y_0.6Ca_0.4Cu₃O₇ showed superconductivity with zero-resistance temperature of 42 K, which was higher than PbBaSrY_0.7Ca_0.3Cu₃O₇ with maximum Ca content for Sr/Ba = 1. Decrease in averaged ionic radii of Ba and Sr in Sr-rich compositions would be favorable for the contraction of Cu-O bonds by hole-doping via Ca substitution for Y.     

Electronic structure characteristic of carbon nanotubules

Electronic structure near the Fermi energy of single-shell carbon nanotubules has been studied within the framework of the tight-binding approximation. The electronic density of states (DOS) of tubules shows a structure consisting of many spike-like peaks. An analytical expression in a π-electron model is derived which predicts not only the energy gap (E _g ) of semiconducting tubules, but also the energy positions of those spike-like peaks in the π-DOS near the Fermi energy in any tubule. The limitation of the π-electron model in tubules is discussed by investigating the effect of σ-πmixing. The position of σ component edge in the DOS is also investigated as a function of tubule radius (R) and chiral angle (θ). It is found that this edge energy is very sensitive to θ and largely changes with R, because the dominant contribution of θ to its change is given by g(θ)/R in contrast to f(θ)/R ² for E _g .     

Ultraviolet-A irradiation to the eye modulates intestinal mucosal functions and properties of mast cells in the mouse

We previously reported that topical irradiation of the eye by ultraviolet-B (UVB) activated hypothalamo-pituitary-adrenal axis (HPA-A) of the mouse to increase 3, 4-dihydroxyphenylalanine (DOPA)-positive melanocytes in the skin by an inducible nitric oxide synthase (iNOS)-dependent mechanism. This work demonstrates that irradiation of the eye by ultraviolet-A (UVA) specifically increased DOPA-positive cells in the mucosa of the jejunum and colon of C57BL/6J mice by some HPA- and iNOS-independent mechanism. UVA-induced increase in DOPA-positive cells in the intestine was inhibited by the administration of hexamethonium or prazosin plus propranolol, blockers for the sympathetic nervous system. UVA irradiation of the eye increased DOPA- and histidine decarboxylase (HDC)-positive cells in the intestinal mucosa of both C57BL/6J and WBB6F1/J mice but not in the mutant strain W/Wv of the latter that lack mast cells. UVA irradiation of the eye suppressed the intestinal peristalsis of control, hypophysectomized or iNOS(-/-) C57BL/6J mice by the mechanism that was inhibited by hexamethonium or prazosin plus propranolol. These observations suggest that UVA irradiation of the eye stimulated the sympathetic nervous system to increase the mucosal DOPA- and HDC-positive mast cells and suppressed the peristalsis of the small intestine of the mouse.     

Targeted Delivery using Immunoliposomes with a Lipid-Modified Antibody-Binding Protein

A recombinant antibody-binding protein originating from streptococcal protein G was modified with lipid in a site-directed manner by genetic engineering. The resulting lipoprotein was incorporated into the surface of liposomes by simple mixing. Immunoliposomes were then prepared by binding anti-IgG antibodies molecules onto the surface of proteoliposome via the lipid-anchored streptococcal protein G. Either small fluorophores or fluorescently labeled proteins were encapsulated into prepared immunoliposomes, and these molecular tracers could be delivered into cells whose surfaces were marked with specific antibodies.     

Selection of DNA aptamers recognizing small cell lung cancer using living cell-SELEX

We applied Systematic Evolution of Ligands by EXponential enrichment using Small Cell Lung Cancer (SCLC) cells. A DNA aptamer was identified and evaluated by fluorescent confocal microscopy and flow cytometry. Our results showed that the DNA aptamer binds to molecules that exist predominantly on target SCLC cell surfaces compared with other types of SCLC cells.     

Properties of ionic liquids containing silver(I) or protic alkylethylenediamine cations with a bis(trifluoromethanesulfonyl)amide anion

Ionic liquids of an N-alkylethylenediamine-silver(I) complex cation (alkyl=hexyl, 2-ethylhexyl, and octyl) or a protic N-alkylethylenediaminium cation (alkyl=butyl, hexyl, 2-ethylhexyl, octyl, decyl, and dodecyl) with a bis(trifluoromethanesulfonyl)amide counter anion (Ag-ILs and PILs, respectively) were prepared and their physicochemical properties were investigated. The trend of solidification decreased in the order octyl?hexyl>2-ethylhexyl for the Ag-ILs, and butyl>dodecyl>decyl>octyl>hexyl?2-ethylhexyl for the PILs. The diffusion coefficients of the cations indicated stronger intermolecular interactions in PILs than in the Ag-ILs because of hydrogen-bonding networks, and it has been revealed that the intermolecular interactions increase in the order, hexyl相似文献   

Application of resonant X-ray emissions for molecular/electronic structure analysis of boron nitrides

* –B1s^-1 transitions were observed in w-BN composed of four-fold boron atoms and in h-BN composed of three-fold boron atoms, when the photon energy of the incident undulator beams coincided with the B1s–B2pπ^* absorption energy. However, no resonance was observed in c-BN composed of four-fold boron atoms. The resonant X-ray emission reflects the electronic structure of unoccupied molecular orbitals which strongly depend on the conformnations of the boron atoms. These findings confirm that resonant X-ray emissions can be useful indices for molecular and electronic structure analysis of boron nitrides. Accepted: 6 March 1997     

The three-dimensional structure of aspergilloglutamic peptidase from Aspergillus niger

Aspergilloglutamic peptidase from Aspergillus niger is a novel pepstatin-insensitive acid endopeptidase distinct from the well-studied aspartic peptidases, and thus is an interesting target for protein structure/function studies. In the present study, we have determined the three-dimensional structure of the enzyme by X-ray crystallography to a 1.4-Å resolution. The results revealed that the enzyme has a unique structure, composed of two seven-stranded anti-parallel β-sheets which form a β-sandwich structure and appear to have a partial two-fold symmetry, suggesting its possible evolution by gene duplication and that the glutamic acid-110 and glutamine-24 in the heavy chain form a catalytic dyad, consistent with our results obtained by site-directed mutagenesis.     

The pion velocity at chiral restoration and the vector manifestation

We study the effects of Lorentz non-invariance on the physical pion velocity at the critical temperature T_c in an effective theory of hidden local symmetry (HLS) with the “vector manifestation” fixed point. We match at a “matching scale” Λ_M the axial-vector current correlator in the HLS with the one in the operator product expansion for QCD, and present the matching condition to determine the bare pion velocity. We find that the physical pion velocity, which is found to be one at T=T_c when starting from the Lorentz invariant bare HLS, remains close to one with the Lorentz non-invariance, v_π(T_c)=0.83–0.99. This result is quite similar to the pion velocity in dense matter.     

Survey and evaluation of available biological reference materials for trace element analysis

Summary A database recently prepared by IAEA contains information on 60 internationally available biological reference materials (BRMs) from 9 producers. The data recorded for each material include: name, code No., cost, list of elements, and minimum weight of material recommended for analysis. For each element the concentration and its confidence interval (CI) are recorded, as well as an indication of whether the concentration value is certified or noncertified (e.g. an information value).Large differences among producers are observed in respect of how the concentration values and their CIs are defined, and how other relevant information is reported in the certificates of analysis. International recommendations on how this should be done generally do not seem to be followed.For several elements of biomedical interest there is a serious lack of BRMs namely: Al, F, I, Mo, Si, Sn and V. In addition, the CIs for the following elements are generally excessively large: Al, As, Cd, Cr, Hg, Mo, Ni, Se and V.