Synthesis of MgB4O7:Dy3+and Thermoluminescent Characteristics at Low Doses of Beta Radiation

The synthesis and thermoluminescent characteristics of dysprosium-doped MgB4O7 are analyzed. The phosphor at different concentrations (0, 0.1, 0.5, 1, 2 and 4 mol%) of the dopant was prepared by the solution-assisted method. The magnesium borate compound was confirmed by X-ray diffraction. The annealing and dopant concentrations effects on the crystalline matrix were investigated. The highest thermoluminescent sensitivity was found with 450°C of annealing temperature and at high Dy3+ concentration too. The un-doped MgB4O7 phosphor shows a broad glow curve which peaked at 199°C and about 306 °C. Introducing Dy3+ dopant in the matrix that behavior was strongly changed. The wide glow curve shows three glow peaks; two small shoulders at 124 and 195 °C, and a highest peak between 323 and 336 °C temperature range. A large linear dose-response (5 – 2000 mGy) beta dose was obtained. The complex glow curves were deconvolved and the kinetics parameters were determined considering the general order kinetics model

Thermoluminescent Characteristics of Li2B4O7 Doped with Mn2+ and Eu3+ Ions

Analysis of thermoluminescent properties were made for two samples; Li2B4O7, Li2B4O7:Mn2+:Eu3+. These samples were prepared by melt quenching method. The glow curves of the samples show two broad peaks at 160º C and 245 ºC, and a high peak at 130ºC for Li2B4O7 doped. The response of the materials were analyzed according to the doses (0.2-80 Gy), fading (0-72 hours) and reproducibility of the experiment (10 times). To determine how the glow curve is formed, thermal bleaching for a dose of 5 Gy were made from room temperature to 300º C. Besides, X-ray diffraction patterns were recorded to identify the structure and grain size of the samples

Thermal Effect on TL Response of Single Doped LiF+NaF:RE Polycrystalline Phosphors

In this work, the sintering and annealing effects on the thermoluminescent (TL) behavior of undoped and rare earth (RE)-doped LiF+NaF powder samples (RE = Ce3+, Eu3+, Lu3+ or Tl+, at 0.5 mol%) was analyzed by evaluating the sensitivity to gamma radiation and TL response of the material. The polycrystalline samples were obtained by solid state reaction at 1000°C. The samples were irradiated in a Gammacell-3000 Elan irradiator loaded with 137Cs sources. The glow curves of the LiF+NaF doped with lutetium or thallium show an intense glow peak at about 175°C and 135°C, respectively. When the phosphor was doped with cerium or europium the glow curves were complex in their structure, with TL peaks observed at 155°C and 165°C, respectively. The linear dose-response was between 10 and 50 Gy for cerium, europium or lutetium doped LiF+NaF samples, while for the thallium doped and undoped samples such intervals were 10-100 Gy and 10-500 Gy, respectively. Because the shape of the glow curves were complex, the analysis was carried out in (i) samples without a sintering treatment where the TL response was found insensitive to pre-irradiation annealing treatment, and (ii) sintered samples (300, 350, 400 or 500 °C), in this last case the TL response was dependent on the annealing temperature (100-400 °C), finally (iii) the kinetics parameters of the glow curves were analyzed by assuming a general order kinetics model. The observed glow curves and TL characteristics of the LiF+NaF:RE phosphor make attractive this material to be useful in gamma dose dosimetry

Synthesis and TL Characterization of Li2B4O7 Doped with Cooper and Manganese

Copper (Cu) and manganese (Mn) doped tissue equivalent Li2B4O7 were prepared by solid state sintering. The glow curves shows a high temperature peak at 222 °C for Li2B4O7:Cu and for Li2B4O7:Mn at 218 °C. Linear dose response is observed up to 140 Gy. With a thermal treatment at 125 °C, the first peak of the phosphors doped with copper (95 °C) and manganese (90 °C) disappears and the main TL peaks remain isolated. The dose rate dependence was studied by exposing the samples at doses of 25 Gy and 250 Gy. At low dose it was observed that the Li2B4O7:Cu TL response has non-dependence on dose rate, and at higher dose was observed that there is a dependence of the TL response with the different dose rateFil: Guarneros Aguilar, C.. Benemérita Universidad Autónoma de Puebla. Facultad de Ciencias Físico-Matemáticas. Posgrado en Física Aplicada; MéxicoFil: Cruz Zaragoza, E.. Universidad Nacional Autónoma de México. Instituto de Ciencias Nucleares. Unidad de Irradiación y Seguridad Radiológica; MicronesiaFil: Marcazzo, Salvador Julian. Universidad Nacional del Centro de la Provincia de Bs.as.. Facultad de Ciencias Exactas. Instituto de Fisica Arroyo Seco; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tandil; ArgentinaFil: Palomino Merino, R.. Benemérita Universidad Autónoma de Puebla. Facultad de Ciencias Físico-Matemáticas. Posgrado en Física Aplicada; MéxicoFil: Espinosa, J.. Benemérita Universidad Autónoma de Puebla. Facultad de Ciencias Físico-Matemáticas. Posgrado en Física Aplicada; Méxic

Radio-Optically- and Thermally Stimulated Luminescence of Zn(BO2)2:Tb3+ exposed to Ionizing Radiation

The optical absorption of zinc tetraborate at different concentrations of the terbium impurity (0, 0.5, 1, 2, 4, 8 mol%) was analyzed. The radioluminescence (RL) emission spectra was obtained after beta irradiation of a 90Sr/90Y source. The RL spectrum showed the characteristics bands of Tb3+ with two main emissions at 489 nm and 546 nm which corresponding to the5D4→7F6 and 5D4→7F5 transitions respectively in this ion. The OSL and TL characteristics have been analyzed. The stimulation blue light (497 nm) of a diode laser at 500 mA was used to bleach the thermoluminescent (TL) signals obtained with 5Gy of 60Co source. The two main glow peaks (79 and 161 °C) are sensitives under 497 nm stimulation, and they were shifted to higher temperature values and faded their TL intensities. Similar behavior of TL glow curves before and after OSL stimulation with blue light was observed when the samples were exposed to 30 Gy gamma dose of 137Cs irradiator. The OSL signal response was linear with the dose range of 1-10 Gy and increased their response up to 200 Gy gamma dose. The OSL shows a bleaching sensitive shallow traps and diminishing the intensity of the TL glow curves remaining a complex traps distribution. The RL, TL and OSL properties were investigated in Zn(BO2)2:Tb3+ phosphor

An in vitro system to silence mitochondrial gene expression

The human mitochondrial genome encodes thirteen core subunits of the oxidative phosphorylation system, and defects in mitochondrial gene expression lead to severe neuromuscular disorders. However, the mech- anisms of mitochondrial gene expression remain poorly understood due to a lack of experimental ap- proaches to analyze these processes. Here, we present an in vitro system to silence translation in purified mitochondria. In vitro import of chemically synthesized precursor-morpholino hybrids allows us to target translation of individual mitochondrial mRNAs. By applying this approach, we conclude that the bicistronic, overlapping ATP8/ATP6 transcript is translated through a single ribosome/mRNA engagement. We show that recruitment of COX1 assembly factors to translating ribosomes depends on nascent chain formation. By defining mRNA-specific interactomes for COX1 and COX2, we reveal an unexpected function of the cytosolic oncofetal IGF2BP1, an RNA-binding protein, in mitochondrial translation. Our data provide insight into mitochondrial translation and innovative strategies to investigate mitochondrial gene expression

Metal-THINGS: The association and optical characterization of SNRs with HI holes in NGC 6946

NGC~6946, also known as the `Fireworks' galaxy, is an unusual galaxy that hosts a total of 225 supernova remnant (SNR) candidates, including 147 optically identified with high [SII]/Ha line ratios. In addition, this galaxy shows prominent HI holes, which were analyzed in previous studies. Indeed, the connection between SNRs and HI holes together with their physical implications in the surrounding gas is worth of attention. This paper explores the connection between the SNRs and the HI holes, including an analysis of their physical link to observational optical properties inside and around the rims of the holes, using new integral field unit (IFU) data from the Metal-THINGS survey. We present an analysis combining previously identified HI holes, SNRs candidates, and new integral field unit (IFU) data from Metal-THINGS of the spiral galaxy NGC 6946. We analyze the distributions of the oxygen abundance, star formation rate surface density, extinction, ionization, diffuse ionized gas, and the Baldwin-Phillips-Terlevich classification throughout the galaxy. By analyzing in detail the optical properties of the 121 previously identify HI holes in NGC 6946, we find that the SNRs are concentrated at the rims of the HI holes. Furthermore, our IFU data shows that the star formation rate and extinction are enhanced at the rims of the holes. To a lesser degree, the oxygen abundance and ionization parameter show hints of enhancement on the rims of the holes. Altogether, this provides evidence of induced star formation taking place at the rims of the holes, whose origin can be explained by the expansion of superbubbles created by multiple supernova explosions in large stellar clusters dozens of Myr ago.Comment: Accepted by A&

Functional upgrading in China’s export processing sector

Functional upgrading occurs when a firm acquires more sophisticated functions within an existing value chain. In this paper, we analyze if there is evidence of this type of upgrading in China’s export processing regime by investigating dynamics in the relative prevalence of Import & Assembly (IA) versus Pure Assembly (PA) processing trade over the period 2000-2013. Firms in both regimes provide similar manufacturing services to foreign companies, but IA firms also conduct the sophisticated tasks of quality control, searching, financing and storing imported materials. Consistent with a trend of functional upgrading, we show that the share of IA trade in total processing trade has increased rapidly during the period 2000-2006, both overall and within product categories. Furthermore, we find that this trend has gone hand in hand with improvements in a sector’s labor productivity and unit values. Against expectations, we find that this process has slowed down notably during the period 2006-2013.status: publishe

High relative abundance of firmicutes and increased TNF-α levels correlate with obesity in children

Objective. To investigate the correlation among pro- or anti-inflammatory cytokines and the two main gut microbiota phyla in obese children. Materials and methods. Anthropometric data were obtained from 890 children under 14 years old to determine the degree of obesity. Serum cytokine concentration was measured by ELISA. Relative abundance of gut microbiota in feces was evaluated by quantitative RealTime PCR assays. Results. Anthropometric and biochemical parameters were statistically higher in overweigth/ obese children (OW/O) than in lean (NW), Increased TNF-α levels were found in obese children that also have a high relative abundance of Firmicutes. Conclusions. Obese children have a high relative abundance of Firmicutes that correlates with increased levels of TNF-α. This is the first study that shows a relation between Firmicute abundance and TNF-α serum concentration in obese children

The Protein Kinase Tor1 Regulates Adhesin Gene Expression in Candida albicans

Eukaryotic cell growth is coordinated in response to nutrient availability, growth factors, and environmental stimuli, enabling cell–cell interactions that promote survival. The rapamycin-sensitive Tor1 protein kinase, which is conserved from yeasts to humans, participates in a signaling pathway central to cellular nutrient responses. To gain insight into Tor-mediated processes in human fungal pathogens, we have characterized Tor signaling in Candida albicans. Global transcriptional profiling revealed evolutionarily conserved roles for Tor1 in regulating the expression of genes involved in nitrogen starvation responses and ribosome biogenesis. Interestingly, we found that in C. albicans Tor1 plays a novel role in regulating the expression of several cell wall and hyphal specific genes, including adhesins and their transcriptional repressors Nrg1 and Tup1. In accord with this transcriptional profile, rapamycin induced extensive cellular aggregation in an adhesin-dependent fashion. Moreover, adhesin gene induction and cellular aggregation of rapamycin-treated cells were strongly dependent on the transactivators Bcr1 and Efg1. These findings support models in which Tor1 negatively controls cellular adhesion by governing the activities of Bcr1 and Efg1. Taken together, these results provide evidence that Tor1-mediated cellular adhesion might be broadly conserved among eukaryotic organisms