scholarly journals Methodological and Conceptual Progresses in Studies on the Latent Tracks in PADC

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2665
Author(s):  
Tomoya Yamauchi ◽  
Masato Kanasaki ◽  
Rémi Barillon
Keyword(s):  
Gamma Ray ◽  
Repeat Unit ◽  
Detection Threshold ◽  
Track Detector ◽  
Hydroxyl Group ◽  
Secondary Electrons ◽  
Repeat Units ◽  
Damage Process ◽  
Definition Of ◽  
Power Region

Modified structure along latent tracks and track formation process have been investigated in poly (allyl diglycol carbonate), PADC, which is well recognized as a sensitive etched track detector. This knowledge is essential to develop novel detectors with improved track registration property. The track structures of protons and heavy ions (He, C, Ne, Ar, Fe, Kr and Xe) have been examined by means of FT-IR spectrometry, covering the stopping power region between 1.2 to 12,000 eV/nm. Through a set of experiments on low-LET radiations—such as gamma ray-, multi-step damage process by electron hits was confirmed in the radiation-sensitive parts of the PADC repeat-unit. From this result, we unveiled for the first-time the layered structure in tracks, in relation with the number of secondary electrons. We also proved that the etch pit was formed when at least two repeat-units were destroyed along the track radial direction. To evaluate the number of secondary electrons around the tracks, a series of numerical simulations were performed with Geant4-DNA. Therefore, we are proposing new physical criterions to describe the detection thresholds. Furthermore, we propose a present issue of the definition of detection threshold for semi-relativistic C ions. Additionally, as a possible chemical criterion, formation density of hydroxyl group is suggested to express the response of PADC.

scholarly journals Methodological and Conceptual Progresses in Studies on the Latent Tracks in PADC

2021 ◽  
Author(s):  
Tomoya Yamauchi ◽  
Masato Kanasaki ◽  
Rémi Barillon
Keyword(s):  
Gamma Ray ◽  
Repeat Unit ◽  
Detection Threshold ◽  
Track Detector ◽  
Hydroxyl Group ◽  
Secondary Electrons ◽  
Repeat Units ◽  
Damage Process ◽  
Definition Of ◽  
Power Region

Modified structure along latent tracks and track formation process have been investigated in poly(allyl diglycol carbonate), PADC, which is well recognized as a sensitive etched track detector. This knowledge is essential to develop novel detectors with improved track registration property. The track structures of protons and heavy ions (He, C, Ne, Ar, Fe, Kr and Xe) have been examined by means of FT-IR spectrometry, covering the stopping power region between 1.2 to 12,000 eV/nm. Through a set of experiments on low-LET radiations – such as gamma ray -, multi-step damage process by electron hits was confirmed in the radiation-sensitive parts of the PADC repeat-unit. From this result, we unveiled for the first-time the layered structure in tracks, in relation with the number of secondary electrons. We also proved that etch pit was formed when at least two repeat-units were destroyed along the track radial direction. To evaluate the number of secondary electrons around tracks, a series of numerical simulations were performed with Geant4-DNA. Therefore, we are proposing new physical criterions to describe the detection thresholds. Futhermore, we propose a present issue of the definition of detection threshold for semi-relativistic C ions. And as a possible chemical criterion, formation density of hydroxyl group is suggested to express the response of PADC.

The Measurements of Natural Radioactivity, (Radon and Gamma concentrations), around the old fertilizer factory in Basrah/Iraq

2015 ◽  
Vol 7 (1) ◽  
pp. 1324-1335
Author(s):  
Jabbar H. Jebur
Keyword(s):  
Effective Dose ◽  
Radon Concentration ◽  
Gamma Ray ◽  
Annual Effective Dose ◽  
Track Detector ◽  
Exhalation Rate ◽  
Hazard Indices ◽  
Radium Equivalent ◽  
Passive Technique ◽  
Radium Activity

Radon concentration, exhalation rate, annual effective dose, radium activity, thorium, uranium potassium and radium equivalent have been measured in the present investigation for soil in the area around the old fertilizer factory in southern of Basrah Governorate. The measurements based on CR39 track detector for passive method, RAD7 for active method and NaI(Tl) for gamma concentration measurements. Average values for radon concentration in soil were 112.04±10.76 Bq/m3 using passive technique and 104.56±6.05 Bq/m3 using RAD7. From the result of the passive technique, area and mass exhalation rates and the annual effective dose were calculated. Gamma ray spectroscopy for the soil samples were performed and found that the average concentrations of 226Ra, 232Th and 40K were 50.89 Bq/kg, 21.74 Bq/kg and 640.4 Bq/kg respectively. Gamma ray hazard indices were calculated and found they are within the world average.

scholarly journals A Mutation of the Yeast Gene Encoding PCNA Destabilizes Both Microsatellite and Minisatellite DNA Sequences

Genetics ◽  
1999 ◽  
Vol 151 (2) ◽  
pp. 511-519 ◽  
Author(s):  
Robert J Kokoska ◽  
Lela Stefanovic ◽  
Andrew B Buermeyer ◽  
R Michael Liskay ◽  
Thomas D Petes
Keyword(s):  
Dna Polymerase ◽  
Repetitive Dna ◽  
Dna Sequences ◽  
Repeat Unit ◽  
Nuclear Antigen ◽  
Temperature Sensitive ◽  
Dinucleotide Repeats ◽  
Yeast Saccharomyces Cerevisiae ◽  
Dna Polymerase Δ ◽  
Repeat Units

AbstractThe POL30 gene of the yeast Saccharomyces cerevisiae encodes the proliferating cell nuclear antigen (PCNA), a protein required for processive DNA synthesis by DNA polymerase δ and ϵ. We examined the effects of the pol30-52 mutation on the stability of microsatellite (1- to 8-bp repeat units) and minisatellite (20-bp repeat units) DNA sequences. It had previously been shown that this mutation destabilizes dinucleotide repeats 150-fold and that this effect is primarily due to defects in DNA mismatch repair. From our analysis of the effects of pol30-52 on classes of repetitive DNA with longer repeat unit lengths, we conclude that this mutation may also elevate the rate of DNA polymerase slippage. The effect of pol30-52 on tracts of repetitive DNA with large repeat unit lengths was similar, but not identical, to that observed previously for pol3-t, a temperature-sensitive mutation affecting DNA polymerase δ. Strains with both pol30-52 and pol3-t mutations grew extremely slowly and had minisatellite mutation rates considerably greater than those observed in either single mutant strain.

The gamma ray detection threshold temperature of different superheated droplet detectors

2018 ◽  
Vol 139 ◽  
pp. 127-130
Author(s):  
Rupa Sarkar ◽  
Prasanna Kumar Mondal ◽  
Barun Kumar Chatterjee
Keyword(s):  
Gamma Ray ◽  
Detection Threshold ◽  
Threshold Temperature

scholarly journals A structure hierarchy for silicate minerals: chain, ribbon, and tube silicates

2020 ◽  
Vol 84 (2) ◽  
pp. 165-244 ◽  
Author(s):  
Maxwell C. Day ◽  
Frank C. Hawthorne
Keyword(s):  
Repeat Unit ◽  
Structural Connectivity ◽  
The Other ◽  
Silicate Minerals ◽  
One Dimensional ◽  
Compositional Range ◽  
Repeat Units ◽  
Sheet Silicates ◽  
Sheet Silicate ◽  
Connectivity Degree

AbstractA structure hierarchy is developed for chain-, ribbon- and tube-silicate based on the connectedness of one-dimensional polymerisations of (TO4)n− tetrahedra, where T = Si4+ plus P5+, V5+, As5+, Al3+, Fe3+, B3+, Be2+, Zn2+ and Mg2+. Such polymerisations are described by a geometrical repeat unit (with ng tetrahedra) and a topological repeat unit (or graph) (with nt vertices). The connectivity of the tetrahedra (vertices) in the geometrical (topological) repeat units is denoted by the expression cTr (cVr) where c is the connectivity (degree) of the tetrahedron (vertex) and r is the number of tetrahedra (vertices) of connectivity (degree) c in the repeat unit. Thus cTr = 1Tr12Tr23Tr34Tr4 (cVr = 1Vr12Vr23Vr34Vr4) represents all possible connectivities (degrees) of tetrahedra (vertices) in the geometrical (topological) repeat units of such one-dimensional polymerisations. We may generate all possible cTr (cVr) expressions for chains (graphs) with tetrahedron (vertex) connectivities (degrees) c = 1 to 4 where r = 1 to n by sequentially increasing the values of c and r, and by ranking them accordingly. The silicate (sensu lato) units of chain-, ribbon- and tube-silicate minerals are identified and associated with the relevant cTr (cVr) symbols. Following description and association with the relevant cTr (cVr) symbols of the silicate units in all chain-, ribbon- and tube-silicate minerals, the minerals are arranged into decreasing O:T ratio from 3.0 to 2.5, an arrangement that reflects their increasing structural connectivity. Considering only the silicate component, the compositional range of the chain-, ribbon- and tube-silicate minerals strongly overlaps that of the sheet-silicate minerals. Of the chain-, ribbon- and tube-silicates and sheet silicates with the same O:T ratio, some have the same cVr symbols (vertex connectivities) but the tetrahedra link to each other in different ways and are topologically different. The abundance of chain-, ribbon- and tube-silicate minerals decreases as O:T decreases from 3.0 to 2.5 whereas the abundance of sheet-silicate minerals increases from O:T = 3.0 to 2.5 and decreases again to O:T = 2.0. Some of the chain-, ribbon- and tube-silicate minerals have more than one distinct silicate unit: (1) vinogradovite, revdite, lintisite (punkaruaivite) and charoite have mixed chains, ribbons and/or tubes; (2) veblenite, yuksporite, miserite and okenite have clusters or sheets in addition to chains, ribbons and tubes. It is apparent that some chain-ribbon-tube topologies are favoured over others as of the ~450 inosilicate minerals, ~375 correspond to only four topologically unique graphs, the other ~75 minerals correspond to ~46 topologically unique graphs.

scholarly journals Gamma-Ray Sensitivity to Dark Matter Subhalo Modelling at High Latitudes

Galaxies ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 90 ◽  
Author(s):  
Francesca Calore ◽  
Moritz Hütten ◽  
Martin Stref
Keyword(s):  
Dark Matter ◽  
Gamma Ray ◽  
Detection Threshold ◽  
Point Sources ◽  
Large Set ◽  
Case Scenario ◽  
Tidal Disruption ◽  
Dwarf Spheroidal Galaxies ◽  
Dark Matter Mass ◽  
The One

Searches for “dark” subhaloes in gamma-ray point-like source catalogues are among promising strategies for indirect dark matter detection. Such a search is nevertheless affected by uncertainties related, on the one hand, to the modelling of the dark matter subhalo distribution in Milky-Way-like galaxies, and, on the other hand, to the sensitivity of gamma-ray instruments to the dark matter subhalo signals. In the present work, we assess the detectability of dark matter subhaloes in Fermi-LAT catalogues, taking into accounts uncertainties associated with the modelling of the galactic subhalo population. We use four different halo models bracketing a large set of uncertainties. For each model, adopting an accurate detection threshold of the LAT to dark matter subhalo signals and comparing model predictions with the number of unassociated point-sources in Fermi-LAT catalogues, we derive upper limits on the annihilation cross section as a function of dark matter mass. Our results show that, even in the best-case scenario (i.e., DMonly subhalo model), which does not include tidal disruption from baryons, the limits on the dark matter parameter space are less stringent than current gamma-ray limits from dwarf spheroidal galaxies. Comparing the results obtained with the different subhalo models, we find that baryonic effects on the subhalo population are significant and lead to dark matter constraints that are less stringent by a factor of ∼2 to ∼5. This uncertainty comes from the unknown resilience of dark matter subhaloes to tidal disruption.

scholarly journals Gamma-ray production in selected Wolf-Rayet binaries

2003 ◽  
Vol 212 ◽  
pp. 150-151
Author(s):  
Paula Benaglia ◽  
Gustavo E. Romero
Keyword(s):  
Particle Acceleration ◽  
Gamma Ray ◽  
Thermal Flux ◽  
Detection Threshold ◽  
High Energy ◽  
Early Type ◽  
Acceleration Region ◽  
Thermal Radio Emission ◽  
Inverse Compton ◽  
Γ Ray

In the colliding wind region of early-type binaries, electrons can be accelerated up to relativistic energies, as demonstrated by the detection of non-thermal radio emission from several WR+OB systems. The particle acceleration region is exposed to strong photon fields, and inverse-Compton cooling of the electrons could result in a substantial high-energy non-thermal flux. We present here preliminary results of a study of the binaries WR 140, WR 146, and WR 147 in the light of recent radio and γ-ray observations. We show that under reasonable assumptions WR 140 can produce the γ-ray flux from the GRO-egret source 3EG J 2022+4317. WR 146 and WR 147 are below the detection threshold.

scholarly journals Bacteriophage-encoded glucosyltransferase GtrII of Shigella flexneri: membrane topology and identification of critical residues

2005 ◽  
Vol 389 (1) ◽  
pp. 137-143 ◽  
Author(s):  
Adele M. LEHANE ◽  
Haralambos KORRES ◽  
Naresh K. VERMA
Keyword(s):  
Sequence Similarity ◽  
Repeat Unit ◽  
Shigella Flexneri ◽  
Membrane Topology ◽  
Transmembrane Helices ◽  
O Antigen ◽  
Repeat Units ◽  
Related Group ◽  
Critical Residues ◽  
O Antigens

The Shigella flexneri serotypes differ in the nature of their O-antigens. The addition of glucosyl or O-acetyl groups to the common backbone repeat units gives rise to the different serotypes. GtrII glucosylates rhamnose III of the O-antigen repeat unit, thus converting serotype Y (which has no modifications to the basic O-antigen repeat unit) into serotype 2a, the most prevalent serotype. In the present study, the topology of GtrII has been determined. GtrII has nine transmembrane helices, a re-entrant loop and three large periplasmic regions. Four critical residues (Glu40, Phe414, Cys435 and Lys478) were identified in two of the periplasmic regions. Despite the lack of sequence similarity between GtrII and the Gtrs from other serotypes, three of the critical residues identified are conserved in the remaining Gtrs. This is consistent with some degree of mechanistic conservation in this functionally related group of proteins.

scholarly journals Isolation of a Pericentromeric Satellite DNA Family in Chnootriba argus (Henosepilachna argus) with an Unusual Short Repeat Unit (TTAAAA) for Beetles

Insects ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 306 ◽  
Author(s):  
Pablo Mora ◽  
Jesús Vela ◽  
Areli Ruiz-Mena ◽  
Teresa Palomeque ◽  
Pedro Lorite
Keyword(s):  
Repetitive Dna ◽  
Satellite Dna ◽  
Repeat Unit ◽  
Pericentromeric Region ◽  
Fish Analysis ◽  
Agricultural Pests ◽  
Base Pairs ◽  
Satellite Dnas ◽  
Repeat Units

Ladybird beetles (Coccinellidae) are one of the largest groups of beetles. Among them, some species are of economic interest since they can act as a biological control for some agricultural pests whereas other species are phytophagous and can damage crops. Chnootriba argus (Coccinellidae, Epilachnini) has large heterochromatic pericentromeric blocks on all chromosomes, including both sexual chromosomes. Classical digestion of total genomic DNA using restriction endonucleases failed to find the satellite DNA located on these heterochromatic regions. Cloning of C0t-1 DNA resulted in the isolation of a repetitive DNA with a repeat unit of six base pairs, TTAAAA. The amount of TTAAAA repeat in the C. argus genome was about 20%. Fluorescence in situ hybridization (FISH) analysis and digestion of chromosomes with the endonuclease Tru9I revealed that this repetitive DNA could be considered as the putative pericentromeric satellite DNA (satDNA) in this species. The presence of this satellite DNA was tested in other species of the tribe Epilachnini and it is also present in Epilachna paenulata. In both species, the TTAAAA repeat seems to be the main satellite DNA and it is located on the pericentromeric region on all chromosomes. The size of this satDNA, which has only six base pairs is unusual in Coleoptera satellite DNAs, where satDNAs usually have repeat units of a much larger size. Southern hybridization and FISH proved that this satDNA is conserved in some Epilachnini species but not in others. This result is in concordance with the controversial phylogenetic relationships among the genera of the tribe Epilachnini, where the limits between genera are unclear.

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