Advantages of the use of solid-state nuclear track detectors in high-temperature plasma experiments

This paper reports on measurements performed with the use of SSNTDs at the PF-1000 Plasma-Focus facility in Warsaw and TEXTOR tokamak in Juelich. Fusion reaction protons were measured within the PF-1000 facility and TEXTOR tokamak.     

Synthesis of Well‐Defined Adenosine Diphosphate Ribose Oligomers

The post‐translational modification of proteins that is known as adenosine diphosphate ribosylation (ADPr) regulates a wide variety of important biological processes, such as DNA‐damage repair and cellular metabolism. This modification is also involved in carcinogenesis and the process of aging. Therefore, a better understanding of the function of ADP‐ribosylation is crucial for the development of novel therapeutics. To facilitate the elucidation of the biology of ADPr, the availability of well‐defined fragments of poly(ADP‐ribose) is essential. Herein we report a solid‐phase synthetic approach for the preparation of ADP‐ribose oligomers of exactly defined length. The methodology is exemplified by the first reported synthesis of an ADP‐ribose dimer and trimer.     

Xenon-sensitized radiolysis of hydrogen sulphide in the presence of HBr,N2O,CCl4, and SF6

The γ-radiolysis of hydrogen sulphide in the excess of xenon : as studied as a function of added HBr, N₂O, CCl₄ and SF₆. Addition of HBr results in the considerable increase of H₂ yield while addition of excess of N₂O, CGl₄ and SF₆ reduces G(H ₂ ) to almost zero. When N₂O is present, the N₂ yield also varies with the H₂S/N₂O ratio, being uninfluenced by the addition of small amounts of SF₆ Consideration of possible ionic and nonionic reactions leads to the conclusion that hot hydrogen atoms play a major role in the formation both of hydrogen and nitrogen. The mechanism of electron attachment and ion recombination processes is proposed which is consistent with all the obtained data.     

MicroITIES Detection of Adenosine Phosphates

The complexation between a triamide ligand derived from tris‐2‐(aminoethyl)amine: N‐{2‐[bis‐(2‐(4‐tert‐butylbenzoyl)‐aminoethyl)‐amino]‐ethyl}4‐tert‐butylbenzamide, L , and the three adenosine‐containing nucleotides, ATP, ADP, and AMP, was investigated by facilitated ion transfer processes through a microhole array film. Differential pulse voltammetry (DPV) was used to measure the transfer currents for the respective nucleotides. The three nucleotides were found to have different transfer potentials with transfer currents proportional to their aqueous concentrations. Based on the differences of the transfer potentials, it is concluded that the host ligand, L, interacts with the phosphate moiety and the Gibbs transfer energy is dominated by the charge generated by the phosphate groups. The linear relationship between the current response and nucleotide concentration forms the basis of an anion sensor with a dynamic range from 0.1 mM to 5 mM .     

Elastic coiled-coils act as energy buffers in the ATP synthase

In the ATP synthase, transmission of energy from the membrane-embedded F0 sector to the catalytic F1 sector is accomplished by two stalks composed of coiled-coils. The great efficiency of the enzyme, despite the presence of a symmetry mismatch between the F1 and F0 sectors, suggests the involvement of elastic elements that store energy during the catalytic cycle. Here, the stalk subunits γ and b are investigated as the source of this elastic compliance using a continuum mechanical model of coiled-coils and energy arguments. The analysis shows that the compliance of both subunits is required for efficient energy transmission between F0 and F1. In addition, the predicted mechanical properties of coiled-coils in the ATP synthase suggest mechanisms whereby regulatory subunits influence the enzyme activity.     

Influence of intensive γ and electron radiation on tracks formation in the PM-355 detectors

Solid-state nuclear track detectors have found wide use in various domains of science and technology, e.g. in plasma experiments. The track detectors used in the fusion-oriented experiments encounter “harsh” conditions (intense X-ray and neutron radiation, heat impact, shock waves and plasma fluxes). Therefore, such detectors should be tested under similar conditions. This paper concerns influence of electron and γ radiation on the track formation in PM-355 detectors. Samples were irradiated with 1.5-MeV protons and ⁴He-ions, and with 5.5 MeV particles. After that they were exposed to γ and electron radiation. Irradiation doses were varied from 100 kGy up to 2000 kGy. The etching was performed in steps, and a bulk etching rate (V_B) was determined versus an absorbed dose of electron and gamma radiation.     

Surface chemical analysis and chromatographic characterization of polyethylenimine-coated hydroxyapatite with various amount of polyethylenimine

Polyethylenimine (PEI) has been widely used as a coating material to produce stationary phase for ion-exchange chromatography of biomolecules. However, a precise study of the PEI coating fraction has been lacking, despite such quantification being very important for fundamental research as well as identifying further industrial applications.In this study, we produced four types of PEI-coated hydroxyapatite (PEI-HAp) with various fractions of PEI (0.16%, 0.5%, 1.0%, 1.5%) using a spray-drying system to evaluate correlations between coating fractions and the thermochemical or chromatographic behaviors of theses products. The thermal analyses of these matrices showed two exothermic peaks when the PEI coating fraction exceeded 1.0%. The one peak indicated a PEI decomposition peak and the other would indicate bond dissociation of PEI layers formed over the HAp surface as the PEI concentration increased. Furthermore, the chromatographic analysis for the surface chemical characteristics showed the correlation between coating fraction and the retention time of protein or nucleotide. Acidic or phosphorylated proteins were more strongly adsorbed as the PEI coating fraction increased when the initial coating fraction was low, but at fraction exceeding 0.5%, constant retention was observed. The retention time of nucleotides increased in proportion to the fraction of PEI added. The good selectivity of PEI-HAp may be attributable to multifunctional interactions of electrostatic and bare Ca sites on HAp, not just the amino sites of PEI. These precise studies of PEI coating fraction are our original novel contributions, which could be achieved by quantitative consideration using thermal analysis and chromatography.     

Electroanalytical Characterization of Adenosine Mono-, Di- and Triphosphate Oxidation on Carbon Electrode

Abstract

Electrochemical oxidation of adenosine mononucleotides was characterized using a pencil graphite carbon electrode for the first time. All three adenosine mononucleotides, adenosine triphosphate (ATP), adenosine diphosphate (ADP), and adenosine monophosphate (AMP), showed irreversible electro-activity at the carbon electrode, yielding a well-defined oxidation current response. The peak potential was highly dependent on pH. The lowest mononucleotide concentration detected was 1 µM. The electro-analytical data presented here for the oxidation of adenosine mononucleotides provides the basis for further bioanalytical investigations related to DNA-drug interactions.     

Effect of low and high concentrations of KCl dopant on ADP crystal properties

The experimental results of the influence of low (1 M%) and high (10 M%) concentrations of potassium chloride (KCl) dopant on ADP crystals are presented. The dopant results in an increase in the metastable zone width leading to an enhanced crystal growth rate, at its low concentrations. In the presence of high concentrations of the dopant in the medium, the growth rate decreases appreciably. Further, low concentrations of dopant improve the crystalline quality with better transparency. The diffraction patterns reveal that there is no change in basic structure except for variation in intensity by doping. Slight broadening is observed in FTIR of ADP in the 3500–3000 cm⁻¹ range in the presence of high [KCl]. It appears that the dopant has not altered much the optical transparency of the crystal. SEM studies of pure and doped samples reveal that structure defect centers are formed in ADP crystals by the dopant. Second harmonic generation (SHG) efficiency measurements indicate that nonlinear optical (NLO) property is enhanced appreciably by [KCl] dopant and the SHG is more pronounced at high concentrations. It seems that the molecular alignment of the crystal facilitates non-linearity in the presence of the dopant.