Search results for "Gate"
showing 10 items of 1811 documents
Excitons and nonlinear optical spectra in conjugated polymers.
1992
Excitons in conjugated polymers are studied theoretically in the Su-Schrieffer-Heeger model supplemented by long-range Coulomb interactions. The relationship between exciton energies and basic interaction parameters is clarified. Linear and third-order nonlinear optical susceptibilities (two-photon absorption, electroabsorption, and third-harmonic generation) have been calculated, elucidating the significance of singlet and triplet excitons and unbound electron-hole pairs. Using only moderate interaction strength, various experiments in polydiacetylene can be interpreted in a consistent way
Cementing agents involved in the macro- and microaggregation of a Mediterranean shrubland soil under laboratory heating
2014
The heating effect on aggregation and cementing agents of a Mediterranean soil was studied in two fractions (macro- and microaggregates) in different environments: under Quercus coccifera soil (UQ), under Rosmarinus officinalis soil (UR) and between plants or bare soil (BS). Samples were heated under laboratory conditions at different temperatures (220, 380, 500, 750 and 1000. °C) to establish their effects on the studied soil properties by comparison with unheated control samples (25. °C). Increasing temperature treatments caused significant changes in most soil variables. In both soil fractions, the presence of vegetation contributed to increase of the soil organic matter (SOM) content, w…
Analysis of Subcellular Components by Fluorescent-Lectin Binding and Flow Cytometry
2003
Because of their extensive availability and the wide spectrum of carbohydrates that may be specifically bound, lectins have become essential reagents for detection and quantitation of glycoconjugates in solution and in cell surfaces, identification and separation of cells, and functional studies based on membrane properties (1,2).
Electrospray ion mobility mass spectrometry of positively charged sodium bis[2-ethythexyl)sulfosuccinate aggregates.
2014
Collision cross-sections (CCS) of positively singly and multiply charged aggregates of the surfactant sodium bis(2-ethylhexyl)sulfosuccinate (AOTNa) in the gas phase have been measured by quadrupole ion mobility time-of-flight mass spectrometry. Calibration of the observed drift times to the CCS of the AOTNa non-covalent aggregates was achieved by collecting, under the same experimental conditions, the drift times of a range of singly and multiply charged polyalanine peptides whose CCS had been obtained by conventional ion mobility spectrometry. Together with an obvious increase of the aggregate cross-section with the aggregation number, it was found that the aggregate cross-section increa…
Living Light-Induced Crystallization-Driven Self-Assembly for Rapid Preparation of Semiconducting Nanofibers.
2018
Well-defined nanostructures composed of conjugated polymers have attracted significant attention due to their intriguing electronic and optical properties. However, precise control of the size and uniformity of these semiconducting nanostructures is still rare and challenging, despite recent advances in strategies to obtain self-assembled nanostructures with narrow dispersions. Herein, we demonstrate the preparation of fluorescent conjugated block copolymers by one-shot polymerization and rapid formation of nanofibers in a few minutes via light-induced crystallization-driven self-assembly, driven by facile cis-to- trans photoisomerization of its poly( p-phenylenevinylene) blocks. Furthermor…
Facile access to foldable redox-active flavin-peptide conjugates
2021
A convenient approach for the synthesis of foldable redox-active flavin peptide conjugates was established. A model β-hairpin oligopeptide motif was utilized to demonstrate that azidolysine side-chains are readily functionalised with an alkyne-bearing flavine derivative. The folding equilibrium of the peptide backbone as well as the redox behaviour of the flavin moieties remains intact after the conjugation.
Conjugate addition of organolithium reagents to α,β-unsaturated carboxylic acids
1999
Abstract Conjugate addition of primary, secondary, tertiary alkyl and phenyl lithium reagents to 2-alkenoic acids affords good yields of branched saturated carboxylic acids. Methyl groups at the α- and β-carbon of the 2-alkenoic acid decrease reactivity as acceptors, and foster deprotonation, respectively. The lithium enediolate resulting from the conjugate addition can react with electrophiles. PM3 calculations are in agreement with the substituent effects.
Combinatorial synthesis of amino acid- and peptide-carbohydrate conjugates on solid phase
2004
Carbohydrates are useful polyfunctional scaffold molecules which allow the selective attachment of a number of different side chains. The combinatorial solid phase synthesis of diverse amino acid or peptide conjugates of a polyfunctional glucose scaffold based on a set of selectively removable and orthogonally stable protecting groups is described. The resulting carbohydrate-peptide hybrids constitute potential turn mimetics.
Photoluminescence ZnO nanorod biosensors for medical and food safety applications
2017
Photoluminescence (PL) ZnO nanorods (NR) are prospect materials for biosensor applications. They can be deposited on solid state substrates and/or dispersed in liquid media. ZnO NRs demonstrate strong UV emission (3.28–3.3 eV), which depends on surface charge, formed by adsorbed molecules. In the present work we report on ZnO NRs, deposited on glass slides, used as biosensor templates for detection food pathogens. Change of ZnO PL after interaction with biomolecules was recorded. Dependence of PL intensity vs concentration of biomolecules was obtained. In the second part, ZnO nanorods were used as PL biomarkers. A suspension of ZnO NRs, conjugated with SSEA-4 antibodies (aSSEA-4) in PBS buf…
Research on the Diurnal Courses of Abscissic Acid, 1-Aminocyclopropane Carboxylic Acid and Its Malonyl Conjugate Contents in Needles of Damaged and U…
1993
Ethylene regulates many aspects of plant growth, development and senescence. The immediate precursor of ethylene was identified as 1-aminocyclopropane carboxylic acid (ACC) [7]. Amrhein et al. [1] discovered that ACC supplied exogenously was efficiently converted into ACC malonyl conjugate (MACC) along with ethylene production.