Vacuum-free femtosecond fiber laser microplasma X-ray source for radiography.

Radiographic imaging using X-rays is a tool for basic research and applications in industry, materials science, and medical diagnostics. In this article, we present a novel approach for the generation of X-rays using a vacuum-free microplasma by femtosecond fiber laser. By tightly focusing a laser pulse onto a micrometer-sized solid density near-surface plasma from a rotating copper target, we demonstrate the generation of Cu K-photons (8-9 keV) with high yield ∼ 1.

Optical Diagnostics of Supercritical CO and CO-Ethanol Mixture in the Widom Delta.

The supercritical CO (scCO) is widely used as solvent and transport media in different technologies. The technological aspects of scCO fluid applications strongly depend on spatial-temporal fluctuations of its thermodynamic parameters. The region of these parameters' maximal fluctuations on the p-T (pressure-temperature) diagram is called Widom delta.

[Trivaline initiates formation of homo- and heteroquadruplex DNA structures].

Formation of heterologous (calf thymus double-stranded DNA) and homologous (linearized pBR322 plasmid double-stranded DNA) quadruplexes upon binding with the simple aliphatic tripeptide derivative (dansyl hydrazide trivaline) was examined by fluorimetry, flow linear and circular dichroism and electron microscopy. The morphology of the rod-like compact particles formed due to the association of double-stranded DNA segments proved to be the same for both DNAs, whereas the stability of the compact DNA structure upon tripeptide removal from the complex with DNA differed substantially for homologous versus non-homologous double-stranded DNA used. The increase of NaCl concentration in the solution up to 30 mM removes the peptide from both types of the complexes completely.

DNA quadruplexes assembled by simple peptide: effects of DNA homology and peptide removal.

Formation of heterologous (calf thymus dsDNA) and homologous (linearized pBR322 plasmid dsDNA) quadruplexes upon binding with the simple aliphatic tripeptide derivative (L-Val)3-N2H2-DNS.CF3COOH-DHTV) was examined by fluorimetry, flow linear (LD), circular dichroism (CD), and electron microscopy (EM). The morphology of the rod-like compact particles formed due to the association of dsDNA segments proved to be the same for both DNAs, whereas the stability of the compact DNA structure upon tripeptide removal from the complex with DNA differed substantially for homologous versus non-homologous dsDNA used.

[The hierarchy of complexes and compact structures of trivaline with nucleic acids. I. Interaction of trivaline with double-stranded DNA].

It was shown that trivaline-poly(U) complexes have no appreciable fluorescence at any peptide concentration if the polymer concentration is less than critical. By electron microscopy it was shown that dsDNA molecules undergo a second step of compactization if polymer and peptide concentrations are high enough. The diameter of this rod-like particles is over 40 nm.