191 research outputs found
thermoluminescence in lif crystals and the role of impurities
Eight nominally pure lithium fluoride crystals, obtained from a single LiF crystal containing less than 100 ppm impurities, were irradiated by gamma-rays from a 60 Co source at room temperature, with doses from 8.4 to 2.5 x 10 5 Gy, but one at -60 °C. Optical density measurements were performed to investigate the radiation-induced color centres (CCs) and to evaluate their concentrations. Thermoluminescence (TL) glow curves were collected and simulated by a first-order kinetics approach, and from the best-fit procedure ten glow peaks (GPs) spanning from 100 to 450 °C were highlighted. A comparative analysis of GP intensities and CC concentrations as a function of the irradiation dose has questioned their association as obtained in previous measurements, showing the impurities, less than 10 18 cm -3 , still playing a predominant role in TL spectra. New measurements on LiF crystals more pure, at least an order of magnitude, are required to establish for sure the association of GPs to CCs
The PHLPP2 phosphatase is a druggable driver of prostate cancer progression
Metastatic prostate cancer commonly presents with targeted, bi-allelic mutations of the PTEN and TP53 tumor suppressor genes. In contrast, however, most candidate tumor suppressors are part of large recurrent hemizygous deletions, such as the common chromosome 16q deletion, which involves the AKT-suppressing phosphatase PHLPP2. Using RapidCaP, a genetically engineered mouse model of Pten/Trp53 mutant metastatic prostate cancer, we found that complete loss of Phlpp2 paradoxically blocks prostate tumor growth and disease progression. Surprisingly, we find that Phlpp2 is essential for supporting Myc, a key driver of lethal prostate cancer. Phlpp2 dephosphorylates threonine-58 of Myc, which renders it a limiting positive regulator of Myc stability. Furthermore, we show that small-molecule inhibitors of PHLPP2 can suppress MYC and kill PTEN mutant cells. Our findings reveal that the frequent hemizygous deletions on chromosome 16q present a druggable vulnerability for targeting MYC protein through PHLPP2 phosphatase inhibitors
Bottom-Up Approach to Eumelanin Photoprotection: Emission Dynamics in Parallel Sets of Water-Soluble 5,6-Dihydroxyindole-Based Model Systems
Effect of dielectric Barrier Discharge Plasma on Alumina electrodes evidenced by Thermoluminescence and Optically Stimulated Luminescence analysis
Early Altered Cells Health Status Detection via Label Free Impedance and Broadband dielectric Spectroscopy
Human cells are able to respond to applied electrical signals and their response is different according to cell health status. In this framework, the electrical bio-impedance can be sensitive tools to monitor cellular health status in addition to other commonly adopted biological methods. Here we show that in vitro cellular lines affected by inflammatory processes or outside insult can be identified by using impedance and broadband dielectric spectroscopy analysis. The analysis of specific parameters of the electrical response evidences modification in the cells compartments. The features of the cell electrical response allow to discriminate between the different processes involved
2D Thermoluminescence imaging of dielectric surface long term charge memory of plasma surface interaction in DBD discharges
The charge trapping effect due to the exposure of alumina surfaces to plasma has been studied
in a volume dielectric barrier discharge (DBD) in Ar and He noble gases. The long lasting
charge trapping of alumina dielectric plates, used as barriers in DBDs, is evidenced by an ex
situ thermoluminescence (TL) experiment performed with a standard and a custom
two-dimensional (2D)-TL apparatus. The spatial density of trapped surface charges is found to
be strongly correlated to the plasma morphology, and the surface spatial memory lasted for
several minutes to hours after plasma exposure. In the case of Ar, the plasma channel impact
signature on the surface shows a higher equivalent radiation dose with respect to the surface
plasma wave and the post-discharge species signature. As a consequence, for the development
of discharges, inside the dielectric surface the availability of lower energy trapped electrons is
larger in the first region of plasma impact. The reported spatial memory increases the
likelihood of the occurrence of plasma filaments in the same position in different runs. In He
plasmas, the dielectric barrier shows an almost uniform distribution of trapped charges,
meaning that there is no preferred region for the development of the discharge. In all cases a
slight asymmetry was shown in the direction of the gas flow. This can be interpreted as being due to the long-living species moving in the direction of the gas flow, corresponding with the
TL side experiment on the sample exposed to the plasma afterglow. The maximum values and the integral of the 2D-TL images showed a linear relation with the total charge per ac cycle,
corresponding with findings for the TL glow curve. In conclusion, 2D-TL images allow the retrieval of information regarding the plasma surface interaction such as the plasma
morphology, trap sites and their activation temperature
The allocation of improvement programs in a flow shop for single and multi-products: A simulation assessment
The continuous improvement is crucial to increase the company's competitiveness in today's market. This paper proposes a multi-dimension simulation environment to test improvement programs in a flow shop context. The simulator developed tests the programs proposed in the literature: centralised, distributed and hybrid. The main original contributions of this research are: a simulation environment with higher details; the analysis of several performance measures as the throughput, lead time, work in process, average utilisation and the defected products for each workstation of the production line; the case of flow shop with multi-products. The experimental plan concerns the change of the following issues: set-up times, bottleneck position and process times. The flow shop without improvement programs is the benchmark of the performance measures. The simulation results show how the centralised policy is the better in a single product case, while the hybrid policy leads to the better results in case of multi-products
Charge trapping induced by plasma in alumina electrode surface investigated by Thermoluminescence and Optically Stimulated Luminescence
The plasma of a dielectric barrier discharge can fill traps in the alumina that cover the electrode.
Trap energies and lifetimes are estimated by thermoluminescence and optically stimulated
luminescence. Comparison with similar results for traps created by other radiation sources clarifies
the mechanisms regulating this effect. Alumina’s trap energies are approximately 1 eV, and the traps
remain active for several days after plasma exposure. These results could be important to keep
dielectric barrier discharge plasmas uniform since a trapped charge can be an electron reservoir
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