bluuebunny/crossref_metadata_2025 huggingface dataset:
Using bioinformatic tools to examine similarities between human PDL-1 protein and common tobacco (Nicotiana tabacum).
Authors: Dib Elie G. , Hill Nicholas , Wollard Jessica , Yoo Ji Woon , Dib Joe E. , Ganguly Anutosh , Cho Clifford
Published: February 2020

70

Background: Human CD274 receptor, known as programmed cell death 1 ligand 1 (RefSeq NP_054862.1), is an inhibitory ligand for Programmed cell death protein 1 (PD1). We aimed in this bioinformatic experiment to identify a homologous PDL-1 protein in plants. Methods: We chose to use tBLASTn because it compares a protein query sequence against a nucleotide sequence database dynamically translated in all six reading frames (both strands). We chose the EST database and restricted our search to plants (Viridiplantae). Results: Using the FASTA sequence of PDL-1 protein, the tBLASTn of the CD274 protein produced a single hit to Nicotiana tabacum (Common tobacco) cDNA, accession number FG181602.1 with E value of 2e-13 and score of 75.9. We translated the FASTA FG181602.1 through ExPASy and after inspecting the results of the 6 open reading frames (ORFs) in comparison with the matching homologous plant protein obtained through tBLASTn above, we found this “novel” protein which we named "PDL1LI". It has the following amino acid sequence: MHAVRRHRGEMHKVALLHNSFLIISILGSYADDFRVMVPTRRLTAARGHSVVLGCEFSPHFGPNPDLSSLVLTWQRQEDSRVVHSFYYERDQLAKQSSAYRNRTALFVTELSKGNASVRIENVGVTDAGRYLCTVSTNQGTNKAELQLDYGAFYTEPRLTINVNSSDVLLQYETEGFPAPVVIWKGEDGENLTDRMKTSVQSNEEMGLYYIKSSYTAPNTPLSLTFTLENHLLHQYLQRPVSYTGGQNSCFYQFIAPVVVS Gor4 shows that our novel PDL1LI protein is 181 amino acids long with 36% alpha helix, 18% extended strand and 46% random coil sequence. According to BLASTp, this protein contains an immunoglobulin domain found in the Ig superfamily in the first half of the protein, and specific domain hits to the Ig_HHLA2, V-set, and IGv domains, with e-values of 1.37e-28, 2.23e-08, and 1.73e-06. Conclusions: Of all the plants, we found a single homology for our original protein PDL1 only in Nicotiana tabacum. We named this novel protein PDL1LI. Tobacco has been implicated in the etiology of several cancers including lung cancer, bladder cancer, head and neck cancers, etc. A wet lab experiment is underway to isolate our novel protein PDL1LI and to study its properties including any possible inhibitory actions on T cells. If confirmed, then we would have elucidated a new carcinogenic mechanism of tobacco.
Glycoprotein D, a checkpoint inhibitor of early T-cell activation, to improve immunogenicity and efficacy of an HPV-16 vaccine in preclinical studies.
Authors: Ertl Hildegund , Xiang Zhiquan , Li Yan , Luber Andrew , Magowan Colin , Zhou Xiang
Published: February 2020

71

Background: CD8+ T cells can inhibit tumor progression, but their induction is hampered by the low immunogenicity of most tumor antigens. HSV-1 glycoprotein D (gD), when genetically expressed as a fusion protein with tumor antigens, serves as a checkpoint inhibitor of the B and T cell attenuator (BTLA)-herpes virus entry mediator (HVEM) pathway, which acts early during T cell activation. HSV-1 gD thereby augments antigen-driven CD8+ T cell responses. We describe the immunogenicity and efficacy of a chimpanzee adenoviral vector (AdC) vaccine containing a detoxified E7/E6/E5(AdC-gDE765dt) sequence of HPV-16 fused into gD. Methods: The frequency of HPV-16 E7-specific CD8+ T-cells was assessed by tetramer staining in C57/Bl6 mice 14 days after a single IM vaccination with AdC vectors encoding wild-type or mutant HPV-16 oncoproteins expressed within gD, a non-HVEM-binding form of gD or without gD. Efficacy was tested in a TC-1 tumor cell challenge model with mice receiving no treatment or a single IM vaccine injection 3 days after tumor cell transplantation. Mice were followed for 80 days. Results: The addition of gD increases HPV-16 E7-specific CD8+ T-cell frequencies approximately 10-fold. T cell responses are similar to AdC vaccines expressing wild-type or mutant oncoproteins within gD. All AdC-gDE765dt treated mice show delayed tumor progression after a single vaccination with 50% of animals remaining tumor-free at study completion. Conclusions: These results show that the addition of gD, an early checkpoint inhibitor, which acts locally at the site of T cell stimulation, to an HPV-16 vaccine markedly improves the vaccine’s immunogenicity and efficacy. AdC-gDE765dt is currently in GMP manufacture for Phase 1 investigation in HPV-16 infected patients.
First-in-human study of the cancer peptide vaccine, TAS0313, in patients with advanced solid tumors: Phase I dose-finding part results.
Authors: Yamamoto Noboru , Sato Jun , Kondo Shunsuke , Koyama Takafumi , Yonemori Kan , Iwasa Satoru , Shimizu Toshio
Published: February 2020

73

Background: TAS0313 is a cancer vaccine cocktail containing three long peptides, with a total of 12 cytotoxic T lymphocyte (CTL) epitope peptides. These peptides were derived from eight cancer-associated antigens that are highly expressed in various cancers. We report the results of a phase I part examining the tolerability, safety, potential efficacy, and immunological responses of 9 and 27 mg TAS0313 in patients (pts) with advanced solid tumors. Methods: The enrolled pts had at least one of the following HLA types: HLA-A*02:01, -A*02:06, -A*02:07, -A*11:01, -A*24:02, -A*31:01, or -A*33:03. TAS0313 was subcutaneously administered on Days 1, 8, and 15 of Cycles 1 and 2 and on Day 1 of Cycle 3 or later in 21-day cycles until disease progression, or unacceptable toxicity. Tolerability was assessed in at least six pts during the first cycle. Tumor response was evaluated using RECIST v1.1. The antigen specific CTL and IgG were analyzed post treatment by blood samples. Optional serial tumor biopsies were performed for tumor infiltrating leukocyte (TIL) analysis. CTL, IgG, and TIL were measured by ELISPOT assay, Luminex assay, and IHC (CD8 positive), respectively. Results: Seventeen pts were enrolled in 9mg (n = 10) and 27mg (n = 7) groups. There was no serious adverse drug reaction (ADR) in any patient. All ADRs were of grade 1 or 2, with the most frequent being dermatological injection site reaction, in 7/10 (70%) and 6/7 (86%) pts and pyrexia, in 1/10 (10%) and 2/7 (29%) for the 9 and 27mg groups, respectively. The best overall response was stable disease, in 2/10 (20%) and 2/7 (28%) pts. One patient with cancer of unknown origin received prolonged administration (over 10 months) of the 9mg dose. Increment of CTL and IgG by treatment were detected in 9 and 27mg groups. TIL counts were increased in 2/3(67%) and 3/4(75%) in 9 and 27mg groups compared with pre-treatment samples, respectively. Conclusions: TAS0313 demonstrated safety, tolerability, and immunological responses in pts with advanced solid tumors in the 9 and 27mg groups. A phase II part, evaluating the efficacy of combination therapy with pembrolizumab in pts with urothelial carcinoma and monotherapy in glioblastoma pts, is currently underway. Clinical trial information: JapicCTI-183824.
The effect of lysosomal-associated membrane protein-1-targeting of Epstein–Barr virus nuclear antigen 1 (EBNA1) on immune response and tumor growth in preclinical studies.
Authors: Sinha Pratima , Rosean Claire Buchta , Heiland Teri
Published: February 2020

74

Background: Epstein-Barr virus (EBV) is an oncogenic γ-herpes virus that infects > 90% of the global population. EBV is the primary cause of infectious mononucleosis and is associated with several epithelial and lymphoid malignancies, including nasopharyngeal carcinoma, gastric carcinoma, non-Hodgkin’s and Hodgkin’s lymphoma. Of these, nasopharyngeal carcinoma is particularly prevalent in East and Southeast Asia and is highly metastatic. Current treatment strategies for nasopharyngeal carcinoma are limited to radiation and chemotherapy, demonstrating a need for new, targeted therapies. Most nasopharyngeal carcinomas express EBNA1, a DNA-binding protein involved in maintenance of the episomal virus genome that is required for EBV latency and associated transformation. Targeting EBNA1 allows for an immunotherapeutic approach, by exploiting the potential of the immune system to recognize tumor cells through their expression of this viral antigen. Methods: We designed a DNA vaccine encoding EBNA1 using the UNITE (UNiversal Intracellular Targeted Expression) platform. The UNITE platform is based in part on lysosomal targeting technology which results in enhanced antigen presentation and a balanced T cell response. Results: We report that the EBNA1-UNITE vaccine induced IFNγ-producing effector memory (EM) CD4+ T and CD8+ T cells with complete rejection of EBNA1-expressing tumors observed in 50% of mice. Mice rejecting tumors were protected from rechallenge with CT26-EBNA1, demonstrating that antigen-specific memory was induced in these animals. Tumor microenvironment (TME) analysis showed vaccine-induced mobilization of effector cells, including tumor infiltration of IL-12-producing type 1 dendritic cells, iNOS-producing M1 macrophages, activated EM CD4+T, and CD8+TNFα+T cells. Furthermore, increased PD-1+CD8+T cells in the TME suggests that a combination strategy with PD-1/PD-L1 blockade may be beneficial in a therapeutic setting. Conclusions: This pre-clinical data suggests that the EBNA1-UNITE vaccine has the potential to be used as an immunotherapeutic agent against EBV-associated cancers.
Association of vitamin D intake with decreased risk of immune checkpoint inhibitor-induced colitis.
Authors: Tyan Kevin , Grover Shilpa , Dougan Michael , Sullivan Ryan J. , Giobbie-Hurder Anita , Blum Steven , Ishizuka Jeffrey Joseph , Qazi Taha , Elias Rawad , Vora Kruti , Ruan Alex , Martin-Doyle William , Eastman Lauren , Davis Meredith , Gargano Maria , Haq Rizwan , Buchbinder Elizabeth Iannotti , Ott Patrick Alexander , Hodi F. Stephen , Rahma Osama E.
Published: February 2020

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Background: There is a lack of predictive markers informing on the risk of colitis in patients treated with immune checkpoint inhibitors (ICIs). The aim of this study was to identify potential factors associated with development of ICI colitis. Methods: We performed a retrospective analysis of melanoma patients at Dana-Farber Cancer Institute who received PD-1, CTLA-4, or combination blockade between May 2011 to October 2017. Clinical and laboratory characteristics associated with pathologically confirmed ICI colitis were evaluated using multivariate logistic regression analyses. External validation was performed on an independent cohort from Massachusetts General Hospital. Results: The discovery cohort included 213 patients of whom 37 developed ICI colitis (17%). The odds of colitis were higher in patients treated with ipilimumab either as monotherapy or in combination with nivolumab compared to those treated with pembrolizumab. Vitamin D use was recorded in 66/213 patients (31%) before starting ICIs. In multivariable regression analysis, vitamin D use conferred significantly reduced odds of developing ICI colitis (OR 0.35, 95% CI 0.1–0.9). These results were confirmed in the validation cohort of 169 patients of whom 49 developed ICI colitis (29%). Pretreatment neutrophil/lymphocyte ratio (NLR) ≥5 predicted reduced odds of colitis (OR 0.34, 95% CI 0.1–0.9) only in the discovery cohort. Conclusions: This is the first study to report that among patients treated with ICIs, vitamin D intake is associated with reduced risk for ICI colitis. This finding is consistent with prior reports of prophylactic use of vitamin D in ulcerative colitis and GVHD. This observation should be validated prospectively in future studies. [Table: see text]
SALVO: Single-arm phase II study of ipilimumab and nivolumab as adjuvant therapy for resected mucosal melanoma.
Authors: McWilliams Robert R. , Holtan Shernan , Pond Gregory Russell , Zakharia Yousef , Curti Brendan D. , Domingo Musibay Evidio , Olszanski Anthony J. , Kottschade Lisa A. , Hauke Ralph J.
Published: February 2020

TPS65

Background: Mucosal melanoma is a rare and, therefore, poorly studied malignancy. Patients with resected primary tumors have a median time to recurrence of 5.5 months. While no one adjuvant therapy is of proven benefit for patients, immunotherapy has shown activity in metastatic mucosal melanoma. Methods: We are performing a single arm, phase II clinical trial through the Midwest Melanoma Partnership/Hoosier Cancer Research Network (6 sites) for resected mucosal melanoma. The primary endpoint is recurrence free survival (RFS), and it will include 36 subjects. Patients must have had an R0 or R1 resection of a mucosal melanoma (sinonasal, anorectal, vulvar, or other), and register within 90 days of surgery. Adjuvant radiation is allowed prior to registration but not required. Therapy consists of ipilimumab (1 mg/kg) and nivolumab (3 mg/kg) IV q3w x 4, then 480 mg nivolumab x 1 year. Statistical power is calculated to be 85% to detect a change in RFS from 5.5 months to 9.5 months, with a one sided alpha of 0.05. Enrollment began Sept 2017, with current participation from 6 large volume centers in the United States, with 17 patients enrolled as of Sept 2019. Full accrual is anticipated to complete by year end 2020. Patients will be followed for RFS and OS. Translational studies will include mutational burden, c-kit, BRAF, NRAS status, and serum markers of immunity -- including soluble PD-L1 and Bim. Clinical trial information: NCT03241186.
Control System (CS) and Data Acquisition (DAQ) architecture for the radiation background monitoring of a Personnel Safety System in the ATLAS cavern
Authors: Adamidi E. , Gazis E. , Nikita K.
Published: February 2020

EDUSAFE is a 4-year Marie Curie ITN project, which focuses on research into the use of Virtual Reality (VR) and Augmented Reality (AR) during planned and emergency maintenance in extreme environments of high radiation background (HEP experiments, nuclear installations, space, deep sea, etc.) The scientific objective of this project is research into advanced VR and AR technologies for a personnel safety system platform, including features, methods and tools. Current technology is not efficient because of significant time-lag in communication and data transmission, missing multi-input interfaces, and simultaneous supervision of multiple workers who are working in the extreme high radiation background environment. The aim is to technically advance and combine several technologies and integrate them as integral part of a personnel safety system to improve safety, maintain availability, reduce errors and decrease the time needed for scheduled or sudden interventions. The research challenges lie in the development of real-time (time-lags less than human interaction speed) data-transmission, instantaneous analysis of data coming from different inputs (vision, sound, touch, buttons), interaction with multiple on-site users, complex interfaces, portability and wearability. The result is an integrated wearable VR/AR system and Control System which can be implemented and tested as a prototype. The LHC at CERN and its existing Personnel Safety System, requirements and protocols will be used as a test and demonstration platform. In this article the progress of the project will be presented and especially the major contribution of the NTUA team in developing and optimizing the Control System (CS) and the Data Acquisition System (DAQ).
Determination of 7Be, 210Pb and 22Na Activity in Air and Rainwater samples by Gamma-ray Spectroscopy
Authors: Savva M. , Anagnostakis M.
Published: February 2020

The activity concentration of cosmogenic radionuclides in atmospheric aerosol has been used in many applications, such as air mass transport models and solar activity reconstructions. One of the most studied cosmogenic radionuclides is 7Be which is being monitored at the Nuclear Engineering Department of the National Technical University of Athens (NED- NTUA) since many years, with high accuracy and precision. Sodium-22 is another cosmogenic radionuclide met in such studies, however less reported due to its very low activity concentration, of the order of 1 μBq/m3 [1], [2] – roughly four orders of magnitude lower than that of 7Be. Besides cosmogenic radionuclides, radionuclides of terrestrial origin like the 222Rn progeny 210Pb are also used in atmospheric aerosol studies. Lead-210 serves as an ideal tracer of continental air masses because 222Rn emission from oceans and lakes is negligible (<1%) compared to land sources. However, its deposition exhibits geographic and seasonal variations depending on 226Ra content of the top soils, soil-porosity and meteorology of a particular region [3]. Values reported for 210Pb activity in the air range from 0.1 to 3.4 mBq/m3 [4]. During this research, an investigation regarding the detection of 210Pb and 22Na in atmospheric aerosol and the determination of 7Be/22Na ratio has been conducted at NED-NTUA. Sampling and analysis methods were appropriately selected to allow for the detection of all three nuclides in aerosol samples. In order to study the role of precipitation in surface air 7Be, 210Pb and 22Na activity concentration, a procedure for collecting and analyzing rainwater was also developed. From the results obtained so far it is concluded that with the sampling and analysis procedures followed, 210Pb can be easily determined with reasonable accuracy. As far as 22Na is concerned, it was concluded that it can be detected although with high uncertainty, since its activity concentration is within the limits of detection.
A simple angle integration method for the determination of capture reaction cross sections
Authors: Michalopoulou-Petropoulou V. , Lagaki V. , Axiotis M. , Foteinou V. , Lagoyannis A. , Provatas G. , Harrisopulos S.
Published: February 2020

In order to determine the cross section of a reaction by the angular distribution method, it is essential to calculate the angular distributions of all secondary transitions that lead to the ground state. This is achieved by analysing spectra from HPGe detectors at various detection angles, which is a time consuming process. In this work, a simpler angle integration method is presented that allows to determine cross sections of capture reactions by measuring spectra at fewer detection angles.
197Au(n,xn) reactions at The Svedberg Laboratory high-energy neutron facility in Uppsal
Authors: Kalamara A. , Vlastou R. , Kokkoris M. , Stamatopoulos A. , Passoth E. , Mattera A. , Lantz M. , Rakopoulos V. , Prokopiev A. , Majerle M.
Published: February 2020

Cross section measurements for the197Au(n,xn) reactions have been performed at The Svedberg Laboratory (TSL) high-energy neutron facility in Uppsala,Sweden. The 45.6 and 58.3 MeVquasi-monoenergetic neutron beams were produced by means of the 7Li(p,n) reaction and were monitored with thin-film breakdown counters (TFBCs). After the end of the irradiations, the activity induced by the neutron beams in the targets and in reference foils, has been measured by a HPGe detector. In order to determine the cross sections of the (n,xn) reactions, the spectral neutron flux distribution is needed, thus the characterization of the beam is of major importance. Therefore, simulations that take into account the whole experimental setup of the irradiation have been performed with the use of MCNP5 code and the results are presented in this work. Currently, further analysis of the data is in progress.
A Study of the Response of Depleted Type p-MOSFETs to Electron Doses
Authors: Fragopoulou M. , Zamani M. , Siskos S. , Laopoulos T. , Konstantakos V. , Sarrabayrouse G.
Published: February 2020

A study of depleted pMOSFETs characteristics performed with electrons, at energies ranging from 6 to 15 MeV delivered by Linac medical accelerator. The depleted pMOSFETs present high sensitivity to electron doses. Linear threshold voltage shift with dose was measured for all the electron’s energies studied. A small decrease of the response was observed with dose rate during irradiations which can be attributed to ELDRS effects.
Resurrected from the dead: Full characterization of an old HPGe detector using γ-ray and CT tomographies coupled to standard calibration techniques and simulations
Authors: Angelopoulou V. , Kouvaris E. , Lagaki V. , Mertzimekis T. J. , Papagiannis P.
Published: February 2020

A decommissioned co-axial HPGe detector has been recently acquired and returned to operational mode in an effort to build an environmental radiation spectrometer at the University of Athens. The new counting station, GEROS (Germanium for Environmental RadiOactivity Studies), was fully characterized prior to operation to obtain detailed information on its linear response, efficiency and energy resolution. In addition to using point-like calibration sources (60Co,137Cs,152Eu and 226Ra), several bulk sample geometries were calibrated by means of an IAEA standard, focusing on soils, sediments and solid materials. In lieu of deteailed technical specifications, the crystal integrity, especially in regards to the dead layer known to build up over the years was studied by means of γ-ray tomography. The 3D geometry of the crystal was fully reconstructed considering the absorption coefficients, and the dead layer thickness was estimated. The overall crystal alignment inside the case was also checked. The results were verified by placing GEROS inside a medical CT scanner and irradiating it to obtain detailed longitudinal and transverse sections. The results were combined to provide input data for subsequent MCNP5 simulations. Good overall agreement between simulations and measurements was achieved. Despite some expected loss of resolution, the detector was found to perform substantially well.
Comparison of MCNP and ERICA codes in two different marine areas
Authors: Pappa F. , Patiris D. L. , Tsabaris C. , Eleftheriou G. , Androulakaki E. G. , Kokkoris M. , Vlastou R.
Published: February 2020

The internal and external dose rates received by a marine organism, were calculated using the MCNP-CP code and the ERICA Assessment Tool. MCNP/MCNPX is a general purpose Monte Carlo code for the transport of all kinds of particles, while ERICA is a more specified software tool for assessing the radiological risk to terrestrial, freshwater and marine biota. A pelagic organism living only in the water medium, was chosen as a start for this comparison. Additionally, two different coastal areas: Stratoni port at Ierissos Gulf, Greece [1] and Shatt al-Arab estuary at Arabic or Persian Gulf [2] were selected. Both areas are receiving the impact of anthropogenic activities as those related with metal mining (Stratoni port) and oil and gas exploration (Arabic/Persian Gulf). The measured concentrations of natural 40K, 210Pb and 208Tl and artificial (137Cs) radionuclides in the surface sediment, were included in the calculations for the estimation of the activity concentrations in the water using the sediment-water distribution coefficient (Kd) of the ERICA database. The preliminary results of MCNP-CP simulations were in good agreement with those of ERICA for all radionuclides.
Remote radiological assessment in the marine environment: A pilot study based on Cs-137 measurements and satellite observations in the Aegean Sea
Authors: Mavrokefalou G. , Florou H. , Sykioti O.
Published: February 2020

A program concept has been developed to utilize sea parameters like sea surface temperature (SST), ocean colour (OC) and sea surface salinity (SSS), in order to explore their potential relations with 137Cs activity concentrations in sea water. These relations are expected to lead to the creation of an innovative tool based on remote sensing data and in real time 137Cs measurements, for the remote radioactivity detection of the Greek marine ecosystem both for routine control and emergency recordings. The presented results are a preliminary effort of the tool’s development. Remote sensing data have been acquired from MIRAS and MODIS instruments on-board ESA-SMOS and NASA-TERRA/AQUA satellites respectively. Satellite data comprise of SST and OC measurements. The ERL’s data of 137Cs activity concentrations (204 measurements) in seawater have been used for the period March 2012 to February 2015. Therefore, a) map analyses in a GIS including interpolation and integration of 83 real time measurements corrected with the effective half live of 7.2 y according to the monthly data of satelites and spatial linear regression have been implemented for the Aegean Sea, b) additional temporal analyses using linear and polynomial regression have been performed for the area of Souda- Crete, for which the most frequent measurements of 137Cs activity concentration in sea water have been measured in ERL. In this study, the first derived results on the correlation between SST measurements with 137Cs activity concentrations are presented, whereas the respective correlation with OC is being under invstigation. Further investigations include multivariate polynomial analyses into the Geographic Information System (GIS) platform with more extensive sampling and satellite data from new systems, whereas comparative correlations of 137Cs with seawater parameters derived by conventional means will be performed.
Deployment of an autonomous apparatus for measuring light scattering in deep sea
Authors: Balasi K. G. , Domvoglou T. , Kiskiras I. , Lenis D. , Maragos N. , Stavropoulos G.
Published: February 2020

The KM3NeT research infrastructure will be a deep sea multidisciplinary observatory in the Mediterranean Sea housing a neutrino telescope. Accurate knowledge of the optical properties of the sea water is important for the best performance of the telescope. In this work we describe the deployment of the equipment that we had previously examined by Monte Carlo (MC) simulations1, in the context of the “scattering experiment” in order to evaluate the parameters describing the scattering characteristics of the sea water.
Neutron-induced fission cross-section measurement of 234U with monoenergetic beams in the keV and MeV range using MicroMegas detectors
Authors: Kanellakopoulos A. , Stamatopoulos A. , Tsinganis A. , Kokkoris M. , Vlastou R. , Kalamara A. , Lagoyannis A. , Axiotis M.
Published: February 2020

The fission cross-section of 234U was measured at incident neutron energies between 300 and 500 keV and 4 and 5 MeV with a setup based on “microbulk” MicroMegas detectors. The standard 235,238U fission cross-sections were used as reference. The neutron beams were produced via the 7Li(p,n) and the 2H(d,n) reactions at the neutron beam facility of the 5.5 MeV Tandem accelerator laboratory at NCSR “Demokritos”. The mass of the actinide content of the targets used and of their impurities was quantitatively determined via α – spectroscopy. The developed methodology and preliminary results are presented.
Installation of a gas terminal stripper and a gas/foil post stripper system at the 5.5 MV Demokritos Tandem Van de Graaff accelerator
Authors: Laoutaris A. , Madesis I. , Dimitriou A. , Lagoyannis A. , Axiotis M. , Andrianis M. , Benis E. P. , Sulik Bela , Zouros T. J. M.
Published: February 2020

A gas stripper system has been installed inside the terminal of the Demokritos TANDEM accelerator, in addition to the existing foil stripper system, while two additional post strippers (one gas and one foil) were also installed in the beam line between the analyzing and switching magnets of the accelerator. These installations were necessary for the production of He-like ion beams used in the APAPES‡ project for the investigation of electron capture phenomena in ion-atom collisions using high resolution zero-degree Auger projectile electron spectroscopy in a dedicated experimental setup already in operation since two years. Older measurements have shown that for He-like ion beams foil stripping results in the production of a mixed-state beam (1s2, 1s2s 3S), while gas stripping in the terminal can produce an almost pure ground-state (1s2) beam. Thus, using both strippers, collision measurements will allow for the selective determination of state-selective capture contributions from either the metastable- (1s2s 3S) or the ground-state of the ion by judicious analysis of both associated projectile K-Auger electron spectra. In addition, post-stripping will allow us to obtain ion charge states whose production is not possible with only one stage of stripping.
Measurement of the differential cross sections of natLi(d,d0) for EBS purposes
Authors: Ntemou E. , Preketes-Sigalas K. , Aslanoglou X. , Foteinou V. , Kokkoris M. , Lagoyannis A. , Misaelides P. , Patronis N. , Provatas G. , Vlastou R.
Published: February 2020

In the present work, the 6,7Li(d,d0)6,7Li elastic scattering differential cross sections were measured in the energy range Elab = 900 – 2000 keV for EBS purposes, using thin lithium targets, made by evaporating natLiF and isotopically enriched 6LiF powder on self-supporting carbon stripping foils, with an ultra-thin Au layer on top for charge normalization purposes. The experiment was carried out in deuteron beam energy steps of 5 to 30 keV, depending on the fine structure of each studied cross section, and for the laboratory scattering angles of 125˚, 140˚, 150˚, 160˚, and 170˚.
Modeling radiative proton-capture reactions in mid-heavy nuclei
Authors: Batziou E. , Koutsilianou V. , Stavropoulos L. , Psaltis A. , Mertzimekis T. J.
Published: February 2020

A systematic study of (p,γ) reactions was carried out using the reaction codes EMPIRΕ, TALYS and NON-SMOKER (web). The calculated (p,γ) cross sections of seed nuclei 89Y, 107,109Ag, 106,108,110Pd, 112Cd, 121,123Sb, 127I, and 133Cs can be used in a three-fold way: (a) perform an intercomparison of the models in a low-energy regime (b) compare existing experimental data to the theoretical predictions and (c) predict cross sections of reactions planned to be studied experimentally in the near future by our group. The results of the study are presented in a concise way focusing on the experimental conditions.
The Athens Mobile γ-Spectrometry System (AMESOS)
Authors: Karailias A. , Lagaki V. , Katsiva C. , Kanellakopoulos A. , Mertzimekis T. J. , Kafantaris F. C. , Godelitsas A.
Published: February 2020

We report on a new mobile γ-spectrometry system (AMESOS) developed at the University of Athens. The system aims at carrying out in situ measurements to study distributions of NORM and TENORM at harsh environments or where sampling is difficult. AMESOS has been characterized by using standard calibration sources and minerals of known, independently determined, U and Th concentrations. Simulations of the system have been performed with MCNP and Geant4. As a proof of good field operation, AMESOS was deployed in a series of measurements at Mt. Kithaeron, near Athens, extending earlier data and estimating absorbed dose rates that concern the public.
MCNP model of the EEAE ACCUSCAN Whole Body Counter
Authors: Sarlikiotis N. , Potiriadis C. , Nikolaki M. , Stamatelatos I. E.
Published: February 2020

Monte Carlo simulations and verification measurements for the efficiency calibration of the ACCUSCAN shadow-shield type Whole Body Counter (WBC) of the Greek Atomic Energy Commission (EEAE) are presented. A model of the counter and RMC-II anthropomorphic phantom was developed using the MCNP code. Full energy peak efficiencies for different phantom positions were calculated for 60Co and 137Cs sources. The deviations between computational and experimental efficiencies were found to be less than 12 % for 60Co and 4 % for 137Cs for the Ge detector and less than 25 % for 60Co and 4 % for 137Cs for the NaI detector. This work contributes to the accurate quantification of internal contamination in individuals accidentally exposed in Greece by the Greek Atomic Energy Commission Laboratories and moreover demonstrates the effectiveness of using computational tools for understanding the calibration of radiation detection systems used for in vivo monitoring.
New Instruments for Nuclear Astrophysics
Authors: Axiotis M. , Lagoyannis A. , Provatas G. , Foteinou V. , Karydas A. , Kantarelou V. , Bazzacco D. , Alvarez C. R. , Napoli D. R. , Menegazzo R. , Harrisopulos S. V.
Published: February 2020

A major task in experimental nuclear astrophysics is the measurement of cross sections of capture reactions. In the last years, the astrophysics group of NCSR “Demokritos” developed and used a method for conducting this kind of research using a 4π NaI γ-detector. Of great importance in this method is the determination of the efficiency of the detector, which depends on the average multiplicity of the γ-cascade de-exciting the entry state of the produced nucleus. Two new experimental setups have been studied and are in course of installation at the Tandem Laboratory of the Institute of Nuclear and Particle Physics of NCSR “Demokritos”, that will provide the possibility for conducting this kind of experiments inhouse. The first one is a new 14x14 inches NaI detector and the second is the BGO Ball of the GASP setup. These detector setups as well as their potential experimental use will be described in detail.
A review of the fission programme at the CERN n_TOF facility
Authors: Tsinganis A. , N_TOF Collaboration For the
Published: February 2020

Since 2001, the scientific programme of the CERN n_TOF facility has focused mainly on the study of radiative neutron capture reactions, which are of great interest to nuclear astrophysics and on neutron-induced fission reactions, which are of relevance for nuclear technology, as well as essential for the development of theoretical models of fission. Taking advantage of the high instantaneous neutron flux and high energy resolution of the facility, as well as of high-performance detection and acquisition systems, accurate new measurements on several long-lived actinides, from 232Th to 245Cm, have been performed so far. Data on these isotopes are needed in order to improve the safety and efficiency of conventional reactors, as well as to develop new systems for nuclear energy production and treatment of nuclear waste, such as Generation IV reactors, Accelerator Driven Systems and reactors based on innovative fuel cycles. A review of the most important results on fission cross-sections and fragment properties obtained at n_TOF for a variety of isotopes is presented along with the perspectives arising from the newly added 19 m flight-path, which will expand the measurement capabilities to even more rare or short-lived isotopes, such as 230Th, 232U, 238Pu and 244Cm.
Atomic Physics at the 5 MV Tandem at Demokritos: the UoC APAPES project
Authors: Madesis I. , Dimitriou A. , Doukas S. , Laoutaris A. , Nounis C. , Lagoyannis A. , Axiotis M. , Mertzimekis T. J. , Harrisopulos S. , Sise O. , Benis E. P. , Sulik B. , Zouros T. J. M.
Published: February 2020

University of Crete (UoC) has initiated the research initiative APAPES funded by THALES‡ that has already set up a new experimental station with a beam line dedicated solely on basic atomic physics research. This new experiment utilizing Zero-degree Auger Projectile Spectroscopy (ΖΑPS) is located at the 5 MV TANDEM accelerator of the National Center for Scientific Research (NCSR) “Demokritos” in Athens, and has been put together to perform high resolution studies of electrons emitted during ion-atom collisions. The apparatus consists of a Hemispherical Deflector Analyzer (HDA) combined with a 2-dimensional Position Sensitive Detector (PSD) and a doubly-differentially pumped gas cell containing the gas-target. The goal is to perform a systematic isoelectronic investigation of K-Auger spectra emitted from pre-excited and ground state He-like ions in collisions with gas targets using novel techniques. So far, various Auger electron spectra produced through collisions of mixed state (1s2, 1s2s3S) C4+ ion beam with various gas targets have been recorded. In addition, detailed simulations using SIMION have also explored the optimal lens voltages and the solid angle correction factors for long-lived metastable states. A terminal gas stripper system is scheduled to be installed in the accelerator, extending its range of available charge states and enabling the production of pure ground state as well as mixed state beams with different metastable fractions, a measurement vital to APAPES. Here, we report on the progress made up to date on the APAPES project, the description of the apparatus, updated results and plans for the near future.
A rebirth of radiation therapy with kV X-rays?
Authors: Kalef-Ezra J.
Published: February 2020

Novel clinical approaches using kV X-ray beams are currently under study, such as selective dose enhancement in malignant tissues due to the enhanced presence of atoms with high atomic number, Z, in tumors relative to normal tissues or the use of heavily spatially fractionated kV X-ray irradiation.Local dose enhancement by high Z atoms: A substantial dose gradient between normal and malignant tissues can be achieved by biologic targeting the cells to be “destroyed” with high Z atoms and its irradiation with photons in the energy region of tens of keV, such as synchrotron produced X-rays of energy above the K-edge. The selective accumulation of high Z atoms can be achieved by various techniques, such as by intravenous administration of a) contrast enhancement agents, b) some chemotherapeutic drugs c) nanoparticles and d) DNA precursors loaded with Z-atoms. Taking into account the limited availability and the high cost of GeV synchrotrons, brachytherapy sources could be used.Microbeam radiation therapy: Studies carried out in experimental models using spatially micro- fractionated beams have shown drastically elevated tissue radiation tolerance, with higher tissue sparing in healthy tissues than in malignant ones. This phenomenon is attributed by some investigators to the proliferation and migration of cells from the “low” dosed regions (~10 Gy) to the adjacent “heavily” dosed regions (many hundreds of grays). Multi-slit collimators allow for the production of X-ray microbeam arrays at 3rd generation synchrotron units. Monte Carlo simulations were tested versus direct dose measurements. Promising preclinical studies carried out so far, trigger studies on the development of alternative less expensive technologies.
A new γ-spectroscopy station at the University of Athens
Authors: Lagaki V. , Kouvaris E. , Mertzimekis T. J.
Published: February 2020

A new γ-spectroscopy station at the University of Athens has been recently deployed. The station is built around a 25% HPGe detector and aims at supporting the environmental radioactivity studies program of the NuSTRAP group at UoA. The detector needs detailed characterization of its efficiency and calibration over a rather wide range of energies. Besides standard calibration point sources (60Co, 137Cs, 152Eu and 226Ra), detector simulations using the Monte Carlo N-particle transport code (MCNP) were performed. Results of the MCNP calculations are shown and compared with real spectra showing satisfactory agreement
The benchmarking procedure: Implementation in the case of proton backscattering
Authors: Paneta V. , Colaux J. , Gurbich A. , Jeynes C. , Kokkoris M. , Lagoyannis A.
Published: February 2020

The benchmarking procedure in IBA regards the validation of charged-particle differential cross- section data via the acquisition of EBS spectra from uniform thick target of known composition followed by their detailed simulation. In the present work such benchmarking measurements have been performed for the elastic scattering of protons on 23Na, 31P and natS in the energy range of 1– 3.5 MeV in steps of 250 keV at three backward angles, at 120.6°, 148.8° and 173.5° in order to validate the corresponding existing evaluated cross-section datasets from SigmaCalc and to facilitate their extension at higher energies. The measurements were performed using the 2 MV Tandetron Accelerator of the Ion Beam Center of the University of Surrey. The EBS spectra acquired were compared with simulated ones using the DataFurnace code, along with an a posteriori treatment of the surface roughness. All the experimental parameters were thoroughly investigated and the results obtained and the discrepancies found are discussed and analyzed. Moreover, the benchmarking procedure in complicated cases, such as the natB(p,p) studied at NCSR “Demokritos”, where background contributions exist, is also discussed.
Nuclear study of the exotic neutrino interactions
Authors: Papoulias D. K. , Kosmas T. S.
Published: February 2020

Open neutrino physics issues require precision studies, both theoretical and experimental ones, and towards this aim coherent neutral current neutrino-nucleus scattering events are expected to be observed soon. In this work, we explore ν -nucleus processes from a nuclear theory point of view and obtain results with high confidence level based on accurate nuclear structure cross sections calculations. The present study explores the differential event rates as well as the total number of events expected to be measured by nuclear detectors, indicating measurable rates. We concentrate on the possibility of detecting supernova neutrinos by using massive detectors like those of the GERDA and SuperCDMS dark matter experiments and at spallation neutron source facilities (at Oak Ridge National Lab) by the COHERENT experiment.
The response of an autonomous underwater telescope to high energy neutrinos for the observation of Gamma-ray bursts (GRBs)
Authors: Balasi K. , Markou C. , Tzamarioudaki K. , Rapidis P. , Drakopoulou E. , Pikounis K. , Begatelas C.
Published: February 2020

The response of an underwater neutrino detector is discussed for investigating its performance to the detection of muons and high energy neutrinos. The afformentioned telescope consists of an autonomous battery operated detector string to a central 4-floor tower. In this aim, we utilised a fast detector simulation program, SIRENE, to simulate the hits from Cherenkov photons at ultra high energies (as high as 1020 eV). In order to optimize the detector, analytical studies for different configurations and characteristics of the photo-multiplier tubes inside the optical modules of the telescope was also examined.
Proton capture reactions in medium-heavy nuclei relevant to p-process nucleosynthesis
Authors: Foteinou V. , Axiotis M. , Lagoyannis A. , Demetriou P. , Becker H.-W. , Rogalla D. , Harissopulos S.
Published: February 2020

Cross-section measurements of proton-capture reactions on Molybdenum isotopes have been performed at beam energies from 2.0 to 6.2 MeV. The cross-section data obtained in this work are compared with those predicted by theory. The latter were calculated using the latest version of the TALYS Hauser-Feshbach (HF) theory code [1] (version 1.6). In these calculations, various phenomenological and (semi)microscopic models were used for the nucleon-nucleus and the α-particle-nucleus optical model potential, the nuclear level densities and the γ-ray strength function.
Studying background processes of the exotic neutrino-nucleus reactions
Authors: Papoulias D. K. , Kosmas T. S.
Published: February 2020

The background processes of the flavour changing neutral current (FCNC) processes, predicted by various new-physics models to occur in the presence of nuclei, are examined by computing the relevant nuclear matrix elements within the context of the quasi-particle RPA using realistic strong two-body forces. Our main goal is to explore the role of the non-standard interactions (NSI) in the leptonic sector and specifically: (i) in lepton flavour violating (LFV) processes involving neutrinos νl and ν ̃l, l = e, μ, τ and (ii) in charged lepton flavour violating (cLFV) processes involving the charged leptons l− or l+. As concrete nuclear system we have chosen the stopping target of μ− → e− conversion experiment, i.e. the 48Ti nucleus of the PRIME/PRISM experiment at J-PARC. This experiment has been designed to reduce the single event sensitivity down to 10−16–10−18 in searching for charged lepton mixing events. We also present, stringent constraints on the flavour violating parameters entering the NSI Lagrangians that have been obtained by taking advantage of our detailed nuclear structure calculations and exploiting the present limits or the sensitivity of the proposed exotic μ− → e− experiments.
Phenomenological implications of Bohr space in six dimensions
Authors: Georgoudis P.
Published: February 2020

The critical point for a second order shape/phase transition in the structural evolution of atomic nuclei, the consequences on the mass parameter and its irrotational flow are discussed after the embedding of Bohr space in six dimensions.
Using synchrotron radiation to study iron phases in Saharan dust samples from Athens skies
Authors: Chatzikonstantinou N. , Mertzimekis T. J. , Godelitsas A. , Gamaletsos P. , Nastos P. , Goettlicher J. , Steininger R.
Published: February 2020

The Sahara desert is the largest source of dust in the world. Saharan dust is characterized by great com- plexity, composed mainly of mixtures of mineral phases (amorphous or crystalline, with particle sizes of the order of μm or even nm). The presence of amorphous components makes it difficult to detect their struc- ture. For this purpose the spectroscopic technique of X–ray absorption fine structure μ–XAFS combined to ultrabright synchrotron SR microbeams is suitable. SR’s main advantage is the recording of spectra in a very short time. In this paper we focus on the study of forms of iron deposited on southeast Mediterranean Sea and mainland of Greece by the waves of Saharan dust. Data collection was carried out at the premises of ANKA (KIT, Germany) on the beamline SUL–X of the environmental research laboratory with advanced X–ray spectroscopic techniques, μ–XRF, μ–XRD and μ–XAFS. Results from the measurements and the simulated spectrum are presented.
Energy Dispersive X-Ray Fluorescence Spectroscopy and Applications in Material Science
Authors: Tsompopoulou E. , Mergia K.
Published: February 2020

Energy dispersive X-ray fluorescence spectroscopy (EDXRF) is a powerful non-destructive technique used to determine the elemental composition of materials. The current work focuses on the installation and optimization of the operation of the EDXRF system developed by Amptek Inc. Furthermore, XRF elemental analysis results of alloys candidate for fusion reactor applications are presented
Sediment pollution by radionuclides and toxic metals in the Ierissos Gulf, North Aegean Sea, Greece
Authors: Pappa F. K. , Tsabaris C. , Kaberi H. , Zeri C. , Androulakaki E. , Pashalidis E. , Ioannidou A. , Kokkoris M. , Eleftheriou G. , Patiris D. L. , Vlastou R.
Published: February 2020

Environmental pollution of industrial areas and especially of areas which contain industries that involve processing of NORM (Naturally Occurring Radioactive Materials), requires monitoring radionuclide activ- ities and trace metal concentration. In the gold mine facility of Stratoni region in Ierissos Gulf, surface sediment samples were analysed regarding TENORM (Technologically Enhanced NORM) and toxic metals (e.g. As, Pb, Cu, Cr and Ni). Radionuclide activity concentrations (226Ra, 214Pb, 214Bi, 210Pb, 228Ac, 212Pb, 212Bi, 208Tl, 40K) were measured by means of gamma-ray spectrometry using a high-purity ger- manium (HPGe) detector, while the trace metals concentrations were determined using the XRF (X-Ray Fluorescence) technique. The results indicate that the surface sediments of the Ierissos Gulf are significantly polluted with As, Pb and Cu. Surface distribution analysis of the studied radionuclides and toxic metals (e.g. TENORM, As, Pb, and Cu) indicates maximum contamination levels close to the factory area, which decrease gradually with increasing distance from the shore. The interpretation of the increased levels is under investigation since the load-out facility of the mining operations in the town of Stratoni affects the whole ecosystem.