Optical properties of substituted phthalocyanine rare-earth metal complexes

Comparative study of optical properties of alkylthio-group-substituted phthalocyanine rare-earth metal sandwich complexes ([(CnS)(8)Pc](2)M,M=Eu,Lu,Tb) is presented. Photoluminescence and photoconductivity of [(CnS)(8)Pc](2)M complex is very weak. Two photoluminescence bands were observed at around 400-650 and 720-800 nm in chloroform solution corresponding to the Soret and Q bands in the absorption spectra, respectively. However, the emission from Eu3+ ion (as well as Tb3+) was not found compared with other Eu complexes because the 5d levels of the Eu3+ ion lie higher than the triplet level of the ligand. The significant enhancement of the photoconductivity of [(C16S)(8)Pc](2)M after C-60 doping is reported. The photoconductivity is positive at the low electric field in the ohmic regime while it becomes negative at the high electric field upon photoexcitation with strongly absorbed light. The negative photoconductivity is attributed to space-charge effects. The mechanism of photoluminescence and photoconductivity are discussed by taking the electronic energy schemes of phthalocyanine ligands and lanthanide ion and C-60 into consideration.ArticleJOURNAL OF APPLIED PHYSICS. 88(12):7137-7143 (2000)journal articl

Optical properties of substituted phthalocyanine rare-earth metal complexes

Comparative study of optical properties of alkylthio-group-substituted phthalocyanine rare-earth metal sandwich complexes ([(CnS)8Pc]2M,M=Eu,Lu,Tb) is presented. Photoluminescence and photoconductivity of [(CnS)8Pc]2M complex is very weak. Two photoluminescence bands were observed at around 400–650 and 720–800 nm in chloroform solution corresponding to the Soret and Q bands in the absorption spectra, respectively. However, the emission from Eu3+ ion (as well as Tb3+) was not found compared with other Eu complexes because the 5d levels of the Eu3+ ion lie higher than the triplet level of the ligand. The significant enhancement of the photoconductivity of [(C16S)8Pc]2M after C60 doping is reported. The photoconductivity is positive at the low electric field in the ohmic regime while it becomes negative at the high electric field upon photoexcitation with strongly absorbed light. The negative photoconductivity is attributed to space-charge effects. The mechanism of photoluminescence and photoconductivity are discussed by taking the electronic energy schemes of phthalocyanine ligands and lanthanide ion and C60 into consideration.This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in K. Yoshino, S. B. Lee, T. Sonoda, H. Kawagishi, R. Hidayat, K. Nakayama, M. Ozaki, K. Ban, K. Nishizawa, K. Ohta, and H. Shirai, Journal of Applied Physics 88, 7137 (2000) and may be found at https://doi.org/10.1063/1.1316050

Secondary Metabolites from an Algicolous Aspergillus versicolor Strain

Two new compounds, asperversin A (1) and 9ξ-O-2(2,3-dimethylbut-3-enyl)brevianamide Q (2), and nine known compounds, brevianamide K (3), brevianamide M (4), aversin (5), 6,8-di-O-methylnidurufin (6), 6,8-di-O-methylaverufin (7), 6-O-methylaverufin (8), 5α,8α-epidioxyergosta-6,22-dien-3β-ol (9), ergosta-7,22-diene-3β,5α,6β-triol (10), and 6β-methoxyergosta-7,22-diene-3β,5α-diol (11), were obtained from the culture of Aspergillus versicolor, an endophytic fungus isolated from the marine brown alga Sargassum thunbergii. The structures of these compounds were established by spectroscopic techniques. Compounds 4, 7 and 8 exhibited antibacterial activities against Escherichia coli and Staphyloccocus aureus, and 7 also showed lethality against brine shrimp (Artemia salina) with an LC50 value of 0.5 μg/mL

Odorranalectin Is a Small Peptide Lectin with Potential for Drug Delivery and Targeting

BACKGROUND: Lectins are sugar-binding proteins that specifically recognize sugar complexes. Based on the specificity of protein-sugar interactions, different lectins could be used as carrier molecules to target drugs specifically to different cells which express different glycan arrays. In spite of lectin's interesting biological potential for drug targeting and delivery, a potential disadvantage of natural lectins may be large size molecules that results in immunogenicity and toxicity. Smaller peptides which can mimic the function of lectins are promising candidates for drug targeting. PRINCIPAL FINDINGS: Small peptide with lectin-like behavior was screened from amphibian skin secretions and its structure and function were studied by NMR, NMR-titration, SPR and mutant analysis. A lectin-like peptide named odorranalectin was identified from skin secretions of Odorrana grahami. It was composed of 17 aa with a sequence of YASPKCFRYPNGVLACT. L-fucose could specifically inhibit the haemagglutination induced by odorranalectin. (125)I-odorranalectin was stable in mice plasma. In experimental mouse models, odorranalectin was proved to mainly conjugate to liver, spleen and lung after i.v. administration. Odorranalectin showed extremely low toxicity and immunogenicity in mice. The small size and single disulfide bridge of odorranalectin make it easy to manipulate for developing as a drug targeting system. The cyclic peptide of odorranalectin disclosed by solution NMR study adopts a beta-turn conformation stabilized by one intramolecular disulfide bond between Cys6-Cys16 and three hydrogen bonds between Phe7-Ala15, Tyr9-Val13, Tyr9-Gly12. Residues K5, C6, F7, C16 and T17 consist of the binding site of L-fucose on odorranalectin determined by NMR titration and mutant analysis. The structure of odorranalectin in bound form is more stable than in free form. CONCLUSION: These findings identify the smallest lectin so far, and show the application potential of odorranalectin for drug delivery and targeting. It also disclosed a new strategy of amphibian anti-infection

Incorporation of pseudouridine into mRNA enhances translation by diminishing PKR activation

Previous studies have shown that the translation level of in vitro transcribed messenger RNA (mRNA) is enhanced when its uridines are replaced with pseudouridines; however, the reason for this enhancement has not been identified. Here, we demonstrate that in vitro transcripts containing uridine activate RNA-dependent protein kinase (PKR), which then phosphorylates translation initiation factor 2-alpha (eIF-2α), and inhibits translation. In contrast, in vitro transcribed mRNAs containing pseudouridine activate PKR to a lesser degree, and translation of pseudouridine-containing mRNAs is not repressed. RNA pull-down assays demonstrate that mRNA containing uridine is bound by PKR more efficiently than mRNA with pseudouridine. Finally, the role of PKR is validated by showing that pseudouridine- and uridine-containing RNAs were translated equally in PKR knockout cells. These results indicate that the enhanced translation of mRNAs containing pseudouridine, compared to those containing uridine, is mediated by decreased activation of PKR

Optical properties of substituted phthalocyanine rare-earth metal complexes

Comparative study of optical properties of alkylthio-group-substituted phthalocyanine rare-earth metal sandwich complexes ([(CnS)(8)Pc](2)M,M=Eu,Lu,Tb) is presented. Photoluminescence and photoconductivity of [(CnS)(8)Pc](2)M complex is very weak. Two photoluminescence bands were observed at around 400-650 and 720-800 nm in chloroform solution corresponding to the Soret and Q bands in the absorption spectra, respectively. However, the emission from Eu3+ ion (as well as Tb3+) was not found compared with other Eu complexes because the 5d levels of the Eu3+ ion lie higher than the triplet level of the ligand. The significant enhancement of the photoconductivity of [(C16S)(8)Pc](2)M after C-60 doping is reported. The photoconductivity is positive at the low electric field in the ohmic regime while it becomes negative at the high electric field upon photoexcitation with strongly absorbed light. The negative photoconductivity is attributed to space-charge effects. The mechanism of photoluminescence and photoconductivity are discussed by taking the electronic energy schemes of phthalocyanine ligands and lanthanide ion and C-60 into consideration.ArticleJOURNAL OF APPLIED PHYSICS. 88(12):7137-7143 (2000)journal articl

Transverse momentum and centrality dependence of dihadron correlations in Au+Au collisions at sqrt(s_NN)=200 GeV: Jet-quenching and the response of partonic matter

Azimuthal angle \Delta\phi correlations are presented for charged hadrons from dijets for 0.4 < p_T < 10 GeV/c in Au+Au collisions at sqrt(s_NN) = 200 GeV. With increasing p_T, the away-side distribution evolves from a broad to a concave shape, then to a convex shape. Comparisons to p+p data suggest that the away-side can be divided into a partially suppressed "head" region centered at Delta\phi ~ \pi, and an enhanced "shoulder" region centered at Delta\phi ~ \pi +/- 1.1. The p_T spectrum for the "head" region softens toward central collisions, consistent with the onset of jet quenching. The spectral slope for the "shoulder" region is independent of centrality and trigger p_T, which offers constraints on energy transport mechanisms and suggests that the "shoulder" region contains the medium response to energetic jets.Comment: 420 authors from 58 institutions, 6 pages, 4 figures. Submitted to Physical Review Letters. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm

Transverse energy production and charged-particle multiplicity at midrapidity in various systems from sNN=7.7\sqrt{s_{NN}}=7.7 to 200 GeV

Measurements of midrapidity charged particle multiplicity distributions, $dN_{\rm ch}/d\eta$, and midrapidity transverse-energy distributions, $dE_T/d\eta$, are presented for a variety of collision systems and energies. Included are distributions for Au$+$Au collisions at $\sqrt{s_{_{NN}}}=200$, 130, 62.4, 39, 27, 19.6, 14.5, and 7.7 GeV, Cu$+$Cu collisions at $\sqrt{s_{_{NN}}}=200$ and 62.4 GeV, Cu$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV, U$+$U collisions at $\sqrt{s_{_{NN}}}=193$ GeV, $d$$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV, $^{3}$He$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV, and $p$$+$$p$ collisions at $\sqrt{s_{_{NN}}}=200$ GeV. Centrality-dependent distributions at midrapidity are presented in terms of the number of nucleon participants, $N_{\rm part}$, and the number of constituent quark participants, $N_{q{\rm p}}$. For all $A$$+$$A$ collisions down to $\sqrt{s_{_{NN}}}=7.7$ GeV, it is observed that the midrapidity data are better described by scaling with $N_{q{\rm p}}$ than scaling with $N_{\rm part}$. Also presented are estimates of the Bjorken energy density, $\varepsilon_{\rm BJ}$, and the ratio of $dE_T/d\eta$ to $dN_{\rm ch}/d\eta$, the latter of which is seen to be constant as a function of centrality for all systems.Comment: 706 authors, 32 pages, 20 figures, 34 tables, 2004, 2005, 2008, 2010, 2011, and 2012 data. v2 is version accepted for publication in Phys. Rev.