Impurity-induced stabilization of Luttinger liquid in quasi-one-dimensional conductors

It is shown theoretically that the Luttinger liquid can exist in quasi-one-dimensional conductors in the presence of impurities in a form of a collection of bounded Luttinger liquids. The conclusion is based on the observation by Kane and Fisher that a local impurity potential in Luttinger liquid acts, at low energies, as an infinite barrier. This leads to a discrete spectrum of collective charge and spin density fluctuations, so that interchain hopping can be considered as a small parameter at temperatures below the minimum excitation energy of the collective modes. The results are compared with recent experimental observation of a Luttinger-liquid-like behavior in thin NbSe₃ and TaS₃ wires.     

4-(Isoindolin-5-yl)amino-4-oxobutyryl-β-alkoxyphenyl-β-alanines, new RGDF mimetics. Synthesis, affinity to fibrinogen receptors, antiaggregatory properties, and their correlation with the hydrophobicity

A new series of RGDF mimetics, derivatives of 4-(isoindolin-5-yl)amino-4-oxobutanoic acid, was synthesized. The compounds obtained inhibit efficiently the thrombocytes aggregation in experiments in vitro; their biological targets are fibrinogen receptors. The antiaggregatory activity and the affinity correlate with the hydrophobicity of the compounds.     

Adsorption of Fire Retardant from Dilute Aqueous Solutions onto Viscose Fiber

The adsorption isotherms of the product of transesterification of dimethyl methylphosphonate (ZG-2), used as fire retardant, from dilute solutions on viscose fiber were determined experimentally at various temperatures. The parameters of pore structure of the fibrous sorbent were estimated using the general equation of the theory of volume filling of micropores.     

DETECTION OF DNA-PSORALEN PHOTOADDUCTS in situ

Abstract— An immunological method, with the use of specific immune serum, has been developed for detection of 8-methoxypsoralen (8-MOP) photoadducts to DNA, formed in situ in cell nuclei, after combined treatment with 8MOP and UV-A irradiation (Zarçbska et al. , 1978). Lymphocytes fixed on slides or in suspension, and cryostat sections of different mammalian tissues, served as antigenic substrate, after treatment with 8-MOP and UV-A in vitro. Specific fluorescence in these substrates was detected in the nuclei after treatment with 30 ˜ 140 kJ/m² UV-A in the presence of 0.1-0.3 μg/cm² 8-MOP. PHA-stimulated-lymphocytes appeared to be the most sensitive substrate.
However, hairless mice treated with high doses of UV-A in vivo , 70 ˜ 360 kJ/m² did not reveal a specific fluorescence of epidermal nuclei, unless a high local concentration of 8-MOP was attained.
The apparent discrepancy in the level of photoadduct detection between the in vitro and in vivo treated specimens was explained by the low number of DNA-8-MOP-photoadducts formed in vivo under these experimental conditions. The relevance of these findings to the role of DNA-8-MOP-photoadducts formed during PUVA photochemotherapy is discussed.     

ON QUOTIENTS OF BRAID GROUPS

ABSTRACT.

Let G be the group ?[t, t ^?1] x ?. By studying the action of the braid group B_n on the set Gⁿ , we obtain representations of B_n into a wreath product of the symmetric group and the general linear group over ?[t, t ^?1]. This in particular recovers the Burau representation of the braid group. Furthermore, some quotients of the braid group are obtained by using the representations found.     

N-terminal tagging strategy for De Novo sequencing of short peptides by ESI-MS/MS and MALDI-MS/MS

The major portion of skin secretory peptidome of the European Tree frog Hyla arborea consists of short peptides from tryptophyllin family. It is known that b-ions of these peptides undergo head-to-tail cyclization, forming a ring that can open, resulting in several linear forms. As a result, the spectrum contains multiple ion series, thus complicating de novo sequencing. This was observed in the Q-TOF spectrum of one of the tryptophyllins isolated from Hyla arborea; the sequence FLPFFP-NH₂ was established by Edman degradation and counter-synthesis. Though no rearrangements were observed in FTICR-MS and MALDI-TOF/TOF spectra, both of them were not suitable for mass-spectrometry sequencing due to the low sequence coverage. To obtain full amino acid sequence by mass spectrometry, three chemical modifications to N-terminal amino moiety were applied. They include acetylation and sulfobenzoylation of N-amino group and its transformation to 2,4,6-trimethylpyridinium by interaction with 2,4,6-trimethylpyrillium tetrafluoroborate. All three reagents block scrambling and provide spectra better than the intact peptide. Unfortunately, all of them also readily react with lysine side chain. Hence, all investigated procedures can be used to improve sequencing of short peptides, while acetylation is the recommended one. It shows excellent results, and it is plain and simple to perform. This is the procedure of choice for MS-sequencing of short peptides by manual or automatic algorithms.     

Spin polarization of the current in a correlated one-dimensional conductor with an impurity

The spin transport as the current flows through an impurity in a one-dimensional conductor is analyzed. The interacting electrons are described in terms of the Luttinger liquid theory. Both the Coulomb and short-range interactions are considered; the latter appears when the gate screens the long-range part of the Coulomb potential. The cases of magnetic and nonmagnetic impurities are considered. It has been revealed that, for a magnetic impurity, the electric current flow induces the generation of the spin current, which has direct and alternating components. At low temperatures and voltages, the current can be completely spin-polarized. For a nonmagnetic impurity, the spin current generation is absent. The spin current flowing though the wire affects the current-voltage characteristic for both magnetic and nonmagnetic impurities. The results have been obtained for a rather strong electron-electron interaction.