bluuebunny/crossref_metadata_2025 huggingface dataset:
Fusion Hindrance and Pauli Blocking in 58Ni + 64Ni
Authors: Stefanini A.M. , Montagnoli G. , Fabbro M. Del , Colucci G. , Čolović P. , Corradi L. , Fioretto E. , Galtarossa F. , Goasduff A. , Grebosz J. , Heine M. , Jaworski G. , Mazzocco M. , Mijatovic T. , Szilner S. , Bajzek M. , Brugnara D. , Siciliano M. , Zanon I.
Published: December 2020

58Ni +64Ni is the first case where the influence of positive Q-value transfer channels on sub-barrier fusion was evidenced, in a very well known experiment by Beckerman et al., by comparing with the two systems 58Ni +58Ni and 64Ni +64Ni. Subsequent measurements on 64Ni +64Ni showed that fusion hindrance is clearly present in this case. On the other hand, no indication of hindrance can be observed for 58Ni +64Ni down to the measured level of 0.1 mb. In the present experiment the excitation function has been extended by two orders of magnitude downward. The cross sections for 58Ni + 64Ni continue decreasing very smoothly below the barrier, down to ≃1 μb. The logarithmic slope of the excitation function increases slowly, showing a tendency to saturate at the lowest energies. No maximum of the astrophysical S-factor is observed. Coupled-channels (CC) calculations using a Woods-Saxon potential and including inelastic excitations only, underestimate the sub-barrier cross sections by a large amount. Good agreement is found by adding two-neutron transfer couplings to a schematical level. This behaviour is quite different from what already observed for 64Ni+64Ni (no positive Q-value transfer channels available), where a clear low-energy maximum of the S-factor appears, and whose excitation function is overestimated by a standard Woods-Saxon CC calculation. No hindrance effect is observed in 58Ni+64Ni in the measured energy range. This trend at deep sub-barrier energies reinforces the recent suggestion that the availability of several states following transfer with Q >0, effectively counterbalances the Pauli repulsion that, in general, is predicted to reduce tunneling probability inside the Coulomb barrier.
Transfer to the continuum of 11Be with the application of ab-initio S-matrix
Authors: Carbone D , Bonaccorso A , Cappuzzello F , Cavallaro M , Hupin G , Navrátil P , Quaglioni S
Published: December 2020

The 9Be(18O,16O)11Be two-neutron transfer reaction at 84 MeV is measured at forward angles to explore the continuum of 11Be nucleus. Transfer-to-the-continuum (TC) reaction calculations are applied using for the first time an ab-initio S-matrix. It is derived from the ab-initio no-core shell model with continuum (NCSMC) method, recently used to describe the bound and continuum spectrum of 11Be. Previously known levels are confirmed and theoretical and experimental evidence for a 9/2+ state at Ex = 5.8 MeV is given, whose configuration is thought to be 10Be(2+) + n(d5/2).
The experiments to determine the electron capture and β-decay of 8B into the highly excited states of 8Be
Authors: Viñals S , Borge M J G , Tengblad O , Nácher E , Benito J , Figuera P , Fraile L M , Fynbo H O U , Gad A , Jensen J , Jonson B , Lica R , Marroquín I , Munch M , Nilsson T , Ovejas J D , Perea A , Riisager K , Smain S , Sotty C
Published: December 2020

The main goal of this work is to study the structure of the highest energy states in 8Be populated following the β+-decay and the electron capture (EC) of 8B. With this aim, two experiments were performed at ISOLDE-CERN in 2017 and 2018. The first experiment had the aim to resolve the 2+ doublet at 16.6 and 16.9 MeV, in order to study their isospin mixing. The second experiment aimed to determine a value or give an experimental upper limit to the branching ratio of the exotic EC-p decay.

In this paper, we present the experimental setups and we discuss the analysis and present the preliminary results obtained so far.
Effective mass and pairing gap in neutron matter
Authors: Palkanoglou G , Ismail N , Buraczynski M , Gezerlis A
Published: December 2020

Microscopic simulations of strongly correlated systems, such as neutron matter (NM), is restricted to a small number of particles due to various complexities. Thus, to understand the physics of infinite systems one has to consider the finite size effects (FSE) arising from these limitations on system size. These conference proceedings are centered around different ways of treating FSE in order to study NM. Specifically, we first present a preliminary study, at the mean field level and beyond, of FSE in the pairing gap of neutron superfluids. We also present a systematic model-independent extraction of the effective mass at various densities in NM using Quantum Monte Carlo (QMC) techniques.
High spin states in the heavy nucleus 208Pb and the coupling of one-particle one-hole states to platonic shapes
Authors: Heusler A
Published: December 2020

Structure, spin, and parity of states in 208Pb at 9 < Ex
< 17 MeV are explained by the weak coupling of the 3−, 4+, 6+ yrast, and the 12+ yrare states to one-particle one-hole yrast and yrare states. The spins of the particle and the hole are coupled in the stretched or nearly stretched mode. The ns-isomerism of three states is shown to derive from the exchange of an intruder hole and the p
1/2 hole.
Thouless-Valatin moment of inertia and removal of the spurious mode in the linear response theory
Authors: Kortelainen Markus
Published: December 2020

Symmetry breaking at the mean-field level leads to an appearance of a symmetry restoring Nambu-Goldstone (NG) mode in the linear response theory. These modes represent a special kind of collective motion of the system. However, they can interfere with the calculated intrinsic physical excitations and, hence, they are often called as spurious modes. I discuss translational and rotational NG mode and the inertia parameter associated with these modes, by using the finite amplitude method formalism. I will also discuss how to remove spurious mode from the calculated transition strength function.
Finite-range separable pairing interaction in Cartesian coordinates
Authors: Romero A. M. , Dobaczewski J. , Pastore A.
Published: December 2020

Within a simple SO(8) algebraic model, the coexistence between isoscalar and isovector pairing modes can be successfully described using a mean-field method plus restoration of broken symmetries. In order to port this methodology to real nuclei, we need to employ realistic density functionals in the pairing channel. In this article, we present an analytical derivation of matrix elements of a separable pairing interaction in Cartesian coordinates and we correct errors of derivations available in the literature. After implementing this interaction in the code HFODD, we study evolution of pairing gaps in the chain of deformed Erbium isotopes, and we compare the results with a standard density-dependent contact pairing interaction.
Structure of Krypton Isotopes using the Generalised Bohr Hamiltonian Method
Authors: Muir David , Próchniak Leszek , Pastore Alessandro , Dobaczewski Jacek
Published: December 2020

We investigate the properties of the excited spectra of the even-even isotopes of krypton using a Generalised Bohr Hamiltonian with three different Skyrme functionals. In particular, we investigate the evolution of the low-lying

2
1
+

and

4
1
+

states and their associated electromagnetic transitions. The model reproduces quite nicely the energy trends apart from 88Kr, where none of the interactions used here are able to grasp a sudden change in the energy spectrum. Additionally, we explore the neutron deficient region 72–76Kr which is a proposed region for shape coexistence. We observe that the model can reproduce the structure of the experimental spectrum of 72Kr exceedingly well.
Role of pair-vibrational correlations in forming the odd-even mass difference
Authors: Neergård Kai , Bentley Ian
Published: December 2020

In the random phase approximation (RPA)-amended Nilsson-Strutinskij method of calculating nuclear binding energies [1, 2], the conventional shell correction terms derived from the independent-nucleon model and the Bardeen-Cooper-Schrieffer pairing theory are supplemented by a term which accounts for the pair-vibrational correlation energy. This term is derived by means of the RPA from a pairing Hamiltonian which includes a neutron-proton pairing interaction. The method was used previously in studies of the pattern of binding energies of nuclei with approximately equal numbers N and Z of neutrons and protons and even mass number A = N + Z. Here it is applied to odd-A nuclei. Three sets of such nuclei are considered: (i) The sequence of nuclei with Z = N – 1 and 25 ⩽ A ⩽ 99. (ii) The odd-A isotopes of In, Sn, and Sb with 46 ⩽ N ⩽ 92. (iii) The odd-A isotopes of Sr, Y, Zr, Nb, and Mo with 60 ⩽ N ⩽ 64. The RPA correction is found to contribute significantly to the calculated odd-even mass differences, particularly in the light nuclei. In the upper sd shell this correction accounts for almost the entire odd-even mass difference for odd Z and about half of it for odd N. The size and sign of the RPA contribution varies, which is explained qualitatively in terms of a closed expression for a smooth RPA counter term.
Relativistic nuclear energy density functional approach to magnetic-dipole excitation
Authors: Oishi Tomohiro , Kružić Goran , Paar Nils
Published: December 2020

Magnetic-dipole (M1) excitations of 18O and 42Ca nuclei are investigated within a relativistic nuclear energy density functional framework. In our last work [1], these nuclei are found to have unique M1 excitation and its sum rule, because of their characteristic structure: the system consists of the shell-closure core plus two neutrons. For a more systematic investigation of the M1 mode, we have implemented a framework based on the relativistic nuclear energy density functional (RNEDF). For benchmark, we have performed the RNEDF calculations combined with the random-phase approximation (RPA). We evaluate the M1 excitation of 18O and 42Ca, whose sum-rule value (SRV) of the M1 transitions can be useful to test the computational implementation [1]. We also apply this RNEDF method to 208Pb, whose M1 property has been precisely measured [2, 3, 4, 5]. Up to the level of the M1 sum rule, our result is in agreement with the experiments, except the discrepancy related with the quenching factors for g coefficients.
Measurement of the structure of potential cluster bands and absolute branching ratios of high-energy states in 18O*
Authors: Pirrie S. , Wheldon C. , Kokalova Tz. , Bishop J. , Hertenberger R. , Wirth H.-F. , Bailey S. , Curtis N. , Dell’Aquila D. , Faestermann Th. , Mengoni D. , Smith R. , Torresi D. , Turner A.
Published: December 2020

The investigation of nuclei with potential α-cluster structure is of great importance to the understanding of nuclear structure, both in the testing of theoretical models and for the study of the synthesis of elements in stars. The 18O nucleus is an excellent candidate to test for such a system, and an experiment has been performed in order to determine the validity of proposed cluster bands in 18O, by measuring absolute branching ratios for high-energy excited states. In order to accurately measure these branching ratios, Monte-Carlo techniques have been employed allowing for the precision reproduction of data gathered throughout the experiment. An in-depth description of the considerations required when simulated data for these experiments and comparisons between features in real and simulated data are presented.
The study of the properties of spontaneously fissioning transfermium nuclei synthesized in the complete fusion reactions with heavy ions
Authors: Svirikhin A I , Andreev A V , Yeremin A V , Izosimov I N , Isaev A V , Kuznetsov A N , Kuznetsova A A , Malyshev O N , Popeko A G , Popov Y A , Sokol E A , Chelnokov M L , Chepigin V I , Schneidman T M , Tezekbayeva M S , Andel B , Mosat P , Kalaninova Z , Asfari M Z , Gall B , Dorvaux O , Piot Julien , Stefanova E A , Tonev D V , Hauschild K , Lopez-Martenz A , Rezynkina K
Published: December 2020

This report describes a series of experiments aimed on investigating characteristics of spontaneous fission of nuclei in the exotic region of short-lived neutron-deficient isotopes with Z ≥ 100. Unique data on the decay properties of neutron-deficient isotopes 244,246Fm, 250No, 252No, 254Rf and 256Rf produced in the complete fusion reactions with accelerated heavy ions 40Ar + 206,208Pb → 246,248Fm*, 48Ca + 204,206Pb → 252,254No*, 50Ti + 206,208Pb →256,258Rf* were obtained in experiments at the VASSILISSA (SHELS) separator combined with a neutron detector.
Probing the nuclear structure of candidates for neutrinoless double-beta decay with fast neutrons
Authors: Yates S W , Mukhopadhyay S , Crider B P , Peters E E , Ramirez A P D
Published: December 2020

The low-lying, low-spin levels of several nuclei which are either the possible parent or daughter for neutrinoless double-beta decay have been studied with the (n,n’γ) reaction. From these measurements, level spins, level lifetimes, γ-ray intensities, and multipole mixing ratios were determined; however, considerable effort must be expended in elaborating the level schemes before comparisons of the level characteristics with large-scale shell model calculations are meaningful.
Teaching university physics to students from different school systems: Australia’s state-based education
Authors: Fraser P R , Sidhu L A , Jovanoski Z , Hutchison W D , Tran T P , Arnold J
Published: December 2020

In Australia, the provision of education is a state or territory responsibility. As different states have different curricula and assessment methods, the competencies of students commencing university studies may vary more than secondary school marks may suggest.

We compare secondary school results with outcomes of first-year undergraduate physics studies, as undertaken at the Australian Defence Force Academy. This institution is quite unique, as it draws a student cohort from each jurisdiction.
Spin-Zero Polarimetry for Linearly Polarised Photons at MAMI
Authors: Powell Abby
Published: December 2020

Background: The tagged Coherent Bremsstrahlung technique is used to provide beams of linearly polarised photons at several of the world’s leading photonuclear facilities, including MAMI in Mainz, ELSA at Bonn, and GlueX at Jefferson Laboratory. The degree of linear polarisation in real photon experiments has direct impact on measurements of polarisation observables. Measurement of the linear polarisation is often the biggest source of systematic error in these experiments. Continuous, in-beam measurement will also allow the beam position to be adjusted to optimise the polarisation. Purpose: To determine whether it is possible to make an improved measurement of the degree of linear polarisation using a polarimeter based on a 12C target. Methods: Coherent π0 meson production from a spin-zero nucleus has a photon asymmetry of 1 and hence provides a direct method of measuring the beam polarisation. Results: Current methods of measurement are being employed as a comparison. Simulated statistics of π0 mesons produced off the polarimeter suggest the measurement is viable. Early results from production data support the viability of live, event-by-event measurements of the polarisation using this method. Conclusions: A spin-zero nucleus such as carbon will be developed as a polarimeter for measuring the degree of linear polarisation in hadron physics experiments with tagged photons of up to 1557 MeV.
Has the neutral double hypernucleus

n∧∧4

been observed?
Authors: Schupp Falk , Bleser Sebastian , Bölting Michael , Pochodzalla Josef , Steinen Marcell , Gaitanos Theodoros
Published: December 2020

The BNL-AGS E906 experiment was the first fully electronic experiment to produce and study double hypernuclei with large statistics. Unfortunately, the interpretation of the measured π−−π− momentum correlation is still blurry because the hypothesized production of

Λ
3

H

+
Λ
4

H

pairs remains questionable. We show, that neither a scenario where the hypernuclei are produced after the capture of a stopped Ξ− by a 9Be nucleus nor interactions of energetic Ξ− with 9 Be nuclei in the target material can produce a sufficient amount of such pairs. We have therefore explored the conjecture that decays of the

n

∧∧
4

may be responsible for the observed structure. Indeed, the inclusion of

n

∧∧
4

with a two-body π− branching ratio of 50% in the statistical multifragmentation model allows to describe the E906 data remarkably well.
Search for η’-mesic nuclei using (p,d) reaction with FRS/Super-FRS at GSI/FAIR
Authors: Tanaka Y. K. , Bagchi S. , Benlliure J. , Dickel T. , Drozd V. , Ekawa H. , Fujioka H. , Geissel H. , Goldenbaum F. , Guo C. , Haettner E. , Harakeh M. N. , Hayano R.S. , Hirenzaki S. , Hornung C. , Igarashi Y. , Ikeno N. , Itahashi K. , Iwasaki M. , Jido D. , Kalantar-Nayestanaki N. , Kanungo R. , Kindler B. , Knöbel R. , Kostyleva D. , Kurz N. , Kuzminchuk N. , Lommel B. , Ma Y. , Matsumoto S. Y. , Metag V. , Minami S. , Moskal P. , Mukha I. , Nagae T. , Nagahiro H. , Nakagawa M. , Ong H. J. , Outa H. , Pietri S. , Plass W. R. , Prochazka A. , Purushothaman S. , Rappold C. , Ritman J. , Rodríguez-Sánchez J.L. , Ruber R. , Rundel O. , Saito T. R. , Scheidenberger C. , Sekiya R. , Serdyuk V. , Simon H. , Sitar B. , Skurzok M. , Strmen P. , Sun B. , Szarka I. , Takechi M. , Tanihata I. , Terashima S. , Weick H. , Yamamoto A. , Zhao J.
Published: December 2020

We plan a semi-exclusive measurement of the 12C(p,dp) reaction to search for η’-mesic nuclei, aiming at investigating in-medium properties of the η′-meson. We employ a 2.5 GeV proton beam impinging on a carbon target to produce η′-mesic 11C nuclei via the 12C(p,d)η′⊗11C reaction. Using coincidence measurements of the forward going deuterons, important for missing-mass spectroscopy, and decay protons emitted from the η′-mesic nuclei. for event selection will provide a high experimental sensitivity to observe η’-mesic nuclei. We will perform the measurements by combining the WASA detector system with the fragment separator FRS at GSI and also with the Super-FRS at FAIR in the future. The plan of the experiments and the present status are reported.
Energy, angular momentum and pressure force distributions inside nucleons
Authors: Lorcé C
Published: December 2020

We review some of the recent developments regarding mass, angular momentum and pressure forces inside hadrons. These properties are all encoded in the energy-momentum tensor of the system, which is described at the non-perturbative level in terms of gravitational form factors. Similarly to electromagnetic form factors, Fourier transforms of gravitational form factors allow one to map out the distribution of the above mechanical properties in position space, providing a whole new way of studying in detail the internal structure of hadrons.
Deeply virtual Compton Scattering off 4He
Authors: Fucini Sara , Scopetta Sergio , Viviani Michele
Published: December 2020

Deeply virtual Compton scattering is a fascinating process which can provide a tomographic view of nuclei and bound nucleons. The first experimental results for 4He targets, recently released at Jefferson Lab, have been analyzed here in a rigorous Impulse Approximation scenario. For both the coherent and incoherent channels of the process, the main experimental observables have been written in terms of state-of-the-art models of the nuclear spectral function and of the parton structure of the bound proton. A good overall agreement with the data is obtained. The calculation shows that a comparison of our conventional results with future precise data can expose novel quark and gluon effects in nuclei.
Proof of Concept for a Virtual Reality Intervention Evaluation and Training Platform for Highly Radioactive Environments
Authors: Cryer Alice , Kapellmann-Zafra Gabriel , Abrego-Hernández Samantha , Marin-Reyes Hector , French Richard
Published: December 2020

This paper presents a novel way to predict radiation dose using immersive Virtual Reality (VR). The platform allows an assessment of proposed interventions in as much detail and time as required. Its purpose is to give users the maximum amount of agency while in the environment. Workers get a realistic experience practising jobs and supervisors can oversee the expected radiation doses for each intervention.

A proof of concept performed and showed the platform returned a comparable result to the real radiation exposure for a predefined route. The errors of the system are dependant on the dose map. With an accurate dose map, the system will produce reliable results.
High resolution β — γ coincidence spectrometry at the UK CTBT Radionuclide Laboratory
Authors: Goodwin M. , Britton R. , Davies A. , Regan P. H. , Bell S.
Published: December 2020

Detection of radioxenon is often considered the most probable indicator of an underground nuclear explosion. GBL15 is the UK’s Comprehensive Nuclear-Test-Ban Treaty Certified Radionuclide Laboratory, operated at AWE Aldermaston and has a history of developing high fidelity coincidence detection systems for particulate radionuclides. The Laboratory also operates a SAUNA II system, using NaI(Tl) and plastic scintillator detectors to measure β –γcoincidences from the decay of the four radioxenon isotopes, namely133Xe,135Xe,131mXe &133mXe. Here the efforts to date in exploring new technologies for next generation laboratory-basedβ – γcoincidence spectrometry for radioxenon measurements are discussed. Results are presented from preliminary measurements using a PIPSBox detector with a high purity germaniumγdetector and the output compared to that of lower resolution systems. This investigation will be used to scope future programmes on the technology used for the measurement of radioactive noble gas nuclides at GBL15.
Targeted α therapy with 213Bi and 225Ac
Authors: Kellerbauer A , Bruchertseifer F , Malmbeck R , Morgenstern A
Published: December 2020

The molecularly targeted treatment of cancerous tumors by the alpha-emitting radionuclides 213Bi and 225Ac has shown remarkable efficacy in clinical trials. Ultimately, this treatment option will be applicable to a wide range of cancers and other diseases, subject to the development of specific radioligands. Currently 225Ac is mainly being produced from the decay of existing stocks of 229Th. The expected wider application for radiotherapy will require many orders of magnitude more radionuclide than can currently be produced. Consequently, various alternative production methods are being pursued.
Application of plasma mass spectrometry for half-life measurement of medium and long-lived radionuclides
Authors: Braysher Emma , Russell Ben , Read David
Published: December 2020

When combined with established primary counting techniques, atom counting using inductively coupled plasma mass spectrometry (ICP-MS) can be a powerful metrological tool for providing updated, precise half-life values for medium and long-lived radionuclides, giving end-users increased confidence in measurement for a range of nuclear applications. ICP-MS is increasingly being used for this application, and this study outlines the methods for atom counting using the latest generation tandem ICP-MS/MS. The aim is to provide a consistent methodology that is currently lacking, and attention is paid to the importance of interference removal and minimising uncertainties, with preliminary results given for uranium isotopes.
Determination of beta-delayed neutron emission probability limits of rhodium isotopes by gamma-ray spectroscopy
Authors: Shearman R , Lorusso G , Boso A , Regan P H , Nishimura S , Xu Z Y , Jungclaus A , Shimizu Y , Simpson G S , Söderström P-A , Watanabe H , Browne F , Doornenbal P , Gey G , Jung H S , Meyer B , Sumikama T , Taprogge J , Vajta Zs , Wu J , Baba H , Benzoni G , Chae K Y , Crespi F C L , Fukuda N , Gernhäuser R , Inabe N , Isobe T , Kajino T , Kameda D , Kim G D , Kim Y-K , Kajouharov I , Kondev F G , Kubo T , Kurz N , Kwon Y K , Lane G J , Li Z , Montaner-Pizá A , Moschner K , Naqvi F , Niikura M , Nishibata H , Odahara A , Orlandi R , Patel Z , Podolyák Zs , Sakurai H , Schaffner H , Schury P , Shibagaki S , Steiger K , Suzuki H , Takeda H , Wendt A , Yagi A , Yoshinaga K
Published: December 2020

The decay of five neutron-heavy rhodium isotopes were studied at the Radioactive Isotope Beam Factory (RIBF) Facility at the RIKEN Nishina Center after relativistic fission of 238U beam on a thick beryllium target. Previously unknown associated gamma-ray decay energies are reported for each nuclide, and through evaluating the intensity of the 2+ → 0+ E2 transition in the even-even palladium daughter nuclei, 120,122,124Pd, from the beta-tagged gamma-ray spectra an upper or lower limit of beta-delayed neutron emission is deduced for each nuclei. A general, expected trend of increasing Pn
is observed in the direction of the neutron drip line.
Optimising sensor geometry of a photodiode based detector for the direct detection of strontium 90 in groundwater
Authors: Turkington Graeme , Gamage Kelum A.A. , Graham James
Published: December 2020

Strontium-90, as one of the primary beta emitting radionuclides produced during nuclear fission, strontium-90 contaminates groundwater at nuclear decommissioning sites after leaks and spills. Its presence in the groundwater presents a long-term site risk, and its activity must be routinely monitored. Existing techniques see groundwater samples collected from deep underground boreholes and sent to remote labs for analysis [1]. These procedures are expensive, time consuming and produce chemical waste, whereby eliminating the need for sample collection and treatment, the net lifetime monitoring costs of strontium 90 can be reduced [2]. In this paper authors present an optimisation of a beta detector, based on submersible photodetector, which can be used in real-time, in-situ beta detection. In order to directly detect and characterise strontium 90 in groundwater, it is essential to maximise the number of beta particles incident on the photodiode surface and ensure that they are fully absorbed within the sensitive region of the detector. This work has developed a Geant4 software framework for investigating the energy deposition by beta particles on photodiode detectors. A series of simulations have been performed to investigate radiation absorption in silicon, cadmium telluride and gallium arsenide detectors. Variations in sensitive area and detector thickness were modeled to determine their suitability for strontium-90 detection in groundwater. The optimal detector geometry of gallium arsenide photodiodes was further investigated. The simulation results and analysis suggest that the optimal detector will feature a large surface area, at least 1 cm2, and an intrinsic layer approximately 400 m thick.
Generalised gamma spectrometry simulator for problems in nuclide identification
Authors: Turner A. , Wheldon C. , Gilbert M.R. , Packer L.W. , Burns J. , Kokalova Wheldon Tz. , Freer M.
Published: December 2020

Improvements in Radio-Isotope IDentification (RIID) algorithms have always been a continuous research focus. However, significant developments in machine learning have recently sparked renewed interest. To provide a rapid development environment for this, a generalised gamma simulator has been built using the GEANT4 toolkit. This enables consideration of a diverse range of radiation sources and shielding scenarios. The simulator currently provides training data for the development of neural network based RIID models.
Features of titanium and aluminum particles combustion
Authors: Belousova N S , Glotov O G , Guskov A V
Published: December 2020

The results of the study of metal particles combustion process in free fall in air are presented. Titanium particles with a size of 120-540 microns and particles-aluminum agglomerates with a size of 540-660 microns were used. The characteristic times of the beginning and the end of fragmentation, the end of combustion were found with help of video filming. The laws of particles motion, in particular, their velocity and coordinate at the moment of the beginning of fragmentation, were determined. The size of titanium particles at which the fragmentation mode changes (“star” and “spruce branch”) were estimated. Condensed combustion products of particles were selected and investigated.
Researching acceleration and deceleration processes of supercavitating strikers under the conditions of hydroballistic track
Authors: Ischenko A N , Burkin V V , Diachkovskiy A S , Chupashev A V
Published: December 2020

Laboratory researches of the processes accompanying high-velocity motion of super-cavitating strikers under water, conducted under the conditions of a hydroballistic track imply the acceleration of a striker within a ballistic barrel to speeds exceeding 200 m/s and consequent partial or complete deceleration within a water tank. The results of experimental and theoretical researches concerning the acceleration and deceleration processes are considered in the given work as well as the estimation of the force and pressure values impacting the striker.
Selection of reagent ratio for hydrogen production via Al nanopowder oxidation
Authors: Morozova O N , Pavlenko A A , Antonnikova A A , Titov S S
Published: December 2020

In the present paper, Al is considered as a basic material for hydrogen production from water because of its high performance, availability, and environmental safety of its reaction products. Here we report the results of experimental trials on the oxidation of Alex-grade Al nanopowder by water when heated and stirred. The plots of pressure and temperature versus Al oxidation time in a high-pressure reactor are given. We show the advantages of hydrogen extraction from hydrogen-containing materials via the oxidation of metal powders. An optimum mass ratio of Al nanopowder to water at which the oxidation reaction takes place to release hydrogen has been identified by varying the reagent ratio. It can be concluded at this point of the study that it is advisable to maintain the H2O-to-Al nanopowder ratio of 11:1 for hydrogen production. Hydrogen resulted from this reaction can be used to supply small-scale power packs based on hydrogen FC.
SHS-synthesis of nanolaminate materials of the system Ti-Cr-Al-C and their term-oxidative stability
Authors: Shulpekov A M , Lepakova O K , Afanasyev N I
Published: December 2020

The features of SHS processes in the powder mixture Ti-Cr-Al-C are studied. It is shown that an increase in the chromium content in the mixture lowers the maximum temperature of the combustion wave front. When the chromium content in the mixture is above 20 wt. % process goes into non-stationary combustion mode. The nanolaminate phases Ti2AlC, Ti3AlC2, or their mixture are formed when the chromium content is up to 20 wt.%. Chromium is embedded in the crystal lattice of MAX phases, replacing titanium in the crystal lattice. The introduction of chromium increases the resistance of the material to oxidation. Samples of composition Ti1.1Cr0.9AlC are not inferior in oxidation resistance to materials based on Cr2AlC. However, their synthesis, in contrast to Cr2AlC, is possible in the autowave mode of SHS at room temperature. This allows them to be recommended for use in parts operating under extreme operating conditions, such as electrical contacts, bearings, heating elements, heat exchangers, as high-temperature ceramics.
The interaction of water vapor molecules with a structure based on carbon nanotubes
Authors: Tarasov E A , Khilchuk M D
Published: December 2020

This paper presents the results of numerical simulations of the interaction of a unit cell of a membrane composed of four open nanotubes and water vapor molecules. A mathematical model was proposed based on the Lenard-Jones potential, and a numerical solution of the equations of motion of a water vapor molecule around a carbon nanotube was constructed. This solution was implemented using the author’s program code in the FORTRAN language. The simulation results show that during the rotation of the unit cell of the membrane, it is possible to change the modes of passage of the membrane in relation to water vapor. These results can be used both in further scientific research and in the creation of various filter materials.
A distinctive release profile of vancomycin and tobramycin from a new and injectable polymeric dicalcium phosphate dehydrate cement (P-DCPD)
Authors: Ren E J , Guardia A , Shi T , Begeman P , Ren W , Vaidya R
Published: December 2020

A novel injectable polymeric dicalcium phosphate dehydrate (P-DCPD) cement was developed with superior mechanical strength and excellent cohesion. The purpose of this study was to assess the in vitro performance of P-DCPD loaded with vancomycin (VAN-P), tobramycin (TOB-P) and combination of both (VAN/TOB-P) (10%, w/w). There is a distinctive release profile between VAN and TOB. VAN-P showed decreased initial burst (<30% within 3 d) and sustained VAN release (76% in 28 d). In the presence of TOB (VAN/TOB-P), >90% of VAN was released within 3 d (p < 0.05). Slow and limited TOB release was observed both in TOB-P (<5%) and in TOB/VAN-P (<1%) over 28 d. Zone of inhibition (ZOI) of Staphylococcus aureus growth showed that eluents collected from VAN-P had stronger and longer ZOI (28 d) than that from TOB-P (14 d, p < 0.05). Direct contact of VAN-P, TOB-P and VAN/TOB-P cements displayed persistent and strong ZOI for >3 weeks. Interestingly, the cement residues (28 d after drug release) still maintained strong ZOI ability. P-DCPD with or without antibiotics loading were nontoxic and had no inferior impacts on the growth of osteoblastic MC3T3 cells. VAN-P and TOB-P were injectable. No significant influence on setting time was observed in both VAN-P (11.7 ± 1.9 min) and VAN/TOB-P (10.8 ± 1.5 min) as compared to control (12.2 ± 2.6 min). We propose that a distinctive release profile of VAN and TOB observed is mainly due to different distribution pattern of VAN and TOB within P-DCPD matrix. A limited release of TOB might be due to the incorporation of TOB inside the crystalline lattice of P-DCPD crystals. Our data supported that the bactericidal efficacy of antibiotics-loaded P-DCPD is not only depend on the amount and velocity of antibiotics released, but also probably more on the direct contact of attached bacteria on the degrading cement surface.
Members of thin Π₁⁰ classes and generic degrees
Authors: Stephan Frank , Wu Guohua , Yuan Bowen
Published: December 2020

A

Π

1

0

\Pi ^{0}_{1}

class

P
P

is thin if every

Π

1

0

\Pi ^{0}_{1}

subclass

Q
Q

of

P
P

is the intersection of

P
P

with some clopen set. In 1993, Cenzer, Downey, Jockusch and Shore initiated the study of Turing degrees of members of thin

Π

1

0

\Pi ^{0}_{1}

classes, and proved that degrees containing no members of thin

Π

1

0

\Pi ^{0}_{1}

classes can be recursively enumerable, and can be minimal degree below

0

′

\mathbf {0}’

. In this paper, we work on this topic in terms of genericity, and prove that all 2-generic degrees contain no members of thin

Π

1

0

\Pi ^{0}_{1}

classes. In contrast to this, we show that all 1-generic degrees below

0

′

\mathbf {0}’

contain members of thin

Π

1

0

\Pi ^{0}_{1}

classes.
Vanishing diffusion limits for planar fronts in bistable models with saturation
Authors: Garrione Maurizio
Published: December 2020

We deal with planar fronts for parameter-dependent reaction-diffusion equations with bistable reaction and saturating diffusive term like
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="u Subscript t Baseline equals epsilon normal d normal i normal v left-parenthesis StartFraction nabla u Over StartRoot 1 plus StartAbsoluteValue nabla u EndAbsoluteValue squared EndRoot EndFraction right-parenthesis plus f left-parenthesis u right-parenthesis comma u equals u left-parenthesis x comma t right-parenthesis comma x element-of double-struck upper R Superscript n Baseline comma t element-of double-struck upper R comma">

u
t

=
ε

d
i
v

(

∇
u

1
+
|
∇
u

|
2

)

+
f
(
u
)
,

u
=
u
(
x
,
t
)
,

x
∈

R

n

,

t
∈

R

,

\begin{equation*}u_t=\varepsilon \, \mathrm {div}\, \left (\frac {\nabla u}{\sqrt {1+\vert \nabla u \vert ^2}}\right ) + f(u), \quad u=u(x, t), \; x \in \mathbb {R}^n, \, t \in \mathbb {R}, \end{equation*}

analyzing in particular their behavior for

ε
→
0

\varepsilon \to 0

. First, we construct monotone and non-monotone planar traveling waves, using a change of variables allowing to analyze a two-point problem for a suitable first-order reduction of the equation above; then, we investigate the asymptotic behavior of the monotone fronts for

ε
→
0

\varepsilon \to 0

, showing their convergence to suitable step functions. A remarkable feature of the considered diffusive term is that the fronts connecting

0
0

and

1
1

are necessarily discontinuous (and steady, namely with

0
0

-speed) for small

ε
\varepsilon

, so that in this case the study of the convergence concerns discontinuous steady states, differently from the linear diffusion case.
MITGARD: an automated pipeline for mitochondrial genome assembly in eukaryotic species using RNA-seq data
Authors: Nachtigall Pedro G , Grazziotin Felipe G , Junqueira-de-Azevedo Inácio L M
Published: December 2020

Motivation

Over the past decade, the field of next-generation sequencing (NGS) has seen dramatic advances in methods and a decrease in costs. Consequently, a large expansion of data has been generated by NGS, most of which have originated from RNA-sequencing (RNA-seq) experiments. Because mitochondrial genes are expressed in most eukaryotic cells, mitochondrial mRNA sequences are usually co-sequenced within the target transcriptome, generating data that are commonly underused or discarded. Here, we present MITGARD, an automated pipeline that reliably recovers the mitochondrial genome from RNA-seq data from various sources. The pipeline identifies mitochondrial sequence reads based on a phylogenetically related reference, assembles them into contigs, and extracts a complete mtDNA for the target species.

Results

We demonstrate that MITGARD can reconstruct the mitochondrial genomes of several species throughout the tree of life. We noticed that MITGARD can recover the mitogenomes in different sequencing schemes and even in a scenario of low-sequencing depth. Moreover, we showed that the use of references from congeneric species diverging up to 30 million years ago (MYA) from the target species is sufficient to recover the entire mitogenome, whereas the use of species diverging between 30 and 60 MYA allows the recovery of most mitochondrial genes. Additionally, we provide a case study with original data in which we estimate a phylogenetic tree of snakes from the genus Bothrops, further demonstrating that MITGARD is suitable for use on biodiversity projects. MITGARD is then a valuable tool to obtain high-quality information for studies focusing on the phylogenetic and evolutionary aspects of eukaryotes and provides data for easily identifying a sample using barcoding, and to check for cross-contamination using third-party tools.
Analysis of selection in protein-coding sequences accounting for common biases
Authors: Del Amparo Roberto , Branco Catarina , Arenas Jesús , Vicens Alberto , Arenas Miguel
Published: December 2020

The evolution of protein-coding genes is usually driven by selective processes, which favor some evolutionary trajectories over others, optimizing the subsequent protein stability and activity. The analysis of selection in this type of genetic data is broadly performed with the metric nonsynonymous/synonymous substitution rate ratio (dN/dS). However, most of the well-established methodologies to estimate this metric make crucial assumptions, such as lack of recombination or invariable codon frequencies along genes, which can bias the estimation. Here, we review the most relevant biases in the dN/dS estimation and provide a detailed guide to estimate this metric using state-of-the-art procedures that account for such biases, along with illustrative practical examples and recommendations. We also discuss the traditional interpretation of the estimated dN/dS emphasizing the importance of considering complementary biological information such as the role of the observed substitutions on the stability and function of proteins. This review is oriented to help evolutionary biologists that aim to accurately estimate selection in protein-coding sequences.
Male-derived copulatory plugs enhance implantation success in female Mus musculus
Authors: Lough-Stevens Michael , Ghione Caleb R , Urness Matthew , Hobbs Adelaide , Sweeney Colleen M , Dean Matthew D
Published: December 2020

Among a wide diversity of sexually reproducing species, male ejaculates coagulate to form what has been termed a copulatory plug. A number of functions have been attributed to copulatory plugs, including the inhibition of female remating and the promotion of ejaculate movement. Here we demonstrate that copulatory plugs also influence the likelihood of implantation, which occurs roughly 4 days after copulation in mice. Using a bead transfer method to control for differences in ejaculate retention and fertilization rates, we show that implantation rates significantly drop among females mated to genetically engineered males incapable of forming plugs (because they lack functional transglutaminase 4, the main enzyme responsible for its formation). Surprisingly, this result does not correlate with differences in circulating progesterone levels among females, an important hormone involved in implantation. We discuss three models that connect male-derived copulatory plugs to implantation success, including the hypothesis that plugs contribute to a threshold amount of stimulation required for females to become receptive to implantation.
Implantation failure and embryo loss contribute to subfertility in female mice mutant for chromatin remodelerCecr2†
Authors: Norton Kacie A , Niri Farshad , Weatherill Chelsey B , Williams Christine E , Duong Kevin , McDermid Heather E
Published: December 2020

Defects in the maternal reproductive system that result in early pregnancy loss are important causes of human female infertility. A wide variety of biological processes are involved in implantation and establishment of a successful pregnancy. Although chromatin remodelers have been shown to play an important role in many biological processes, our understanding of the role of chromatin remodelers in female reproduction remains limited. Here, we demonstrate that female mice mutant for chromatin remodeler Cecr2 are subfertile, with defects detected at the peri-implantation stage or early pregnancy. Using both a less severe hypomorphic mutation (Cecr2GT) and a more severe presumptive null mutation (Cecr2Del), we demonstrate a clear difference in the severity of the phenotype depending on the mutation. Although neither strain shows detectable defects in folliculogenesis, both Cecr2GT/GT and Cecr2GT/Del dams show defects in pregnancy. Cecr2GT/GT females have a normal number of implantation sites at embryonic day 5.5 (E5.5), but significant embryo loss by E10.5 accompanied by the presence of vaginal blood. Cecr2GT/Del females show a more severe phenotype, with significantly fewer detectable implantation sites than wild type at E5.5. Some Cecr2GT/Del females also show premature loss of decidual tissue after artificial decidualization. Together, these results suggest a role for Cecr2 in the establishment of a successful pregnancy.
Immunogenicity and Safety of the 9-Valent Human Papillomavirus Vaccine in Solid Organ Transplant Recipients and Adults Infected With Human Immunodeficiency Virus (HIV)
Authors: Boey Lise , Curinckx Ans , Roelants Mathieu , Derdelinckx Inge , Van Wijngaerden Eric , De Munter Paul , Vos Robin , Kuypers Dirk , Van Cleemput Johan , Vandermeulen Corinne
Published: December 2020

Background

The burden of human papillomavirus (HPV) in human immunodeficiency virus (HIV)-infected persons and solid organ transplant (SOT) recipients is high. Clinical trials on HPV vaccines in persons living with HIV and particularly in SOT recipients have been sparse to date, included low numbers of participants, and none of them assessed the 9-valent HPV (9vHPV) vaccine. We investigated the immunogenicity with respect to HPV types 6, 11, 16, 18, 31, 33, 45, 52, and 58 and the safety of the 9vHPV vaccine in persons living with HIV and recipients of a kidney, lung, or heart transplant.

Methods

This is a phase III investigator-initiated study in 100 persons living with HIV (age 18–45 years) and 171 SOT recipients (age 18–55 years). The 9vHPV vaccine was administered at day 1, month 2, and month 6. Primary outcome was seroconversion rates to the 9vHPV types at month 7. Secondary outcomes were geometric mean titers (GMTs) and frequency of adverse events (AEs).

Results

All HIV-infected participants seroconverted for all HPV types, but seroconversion ranged from 46% for HPV45 to 72% for HPV58 in SOT recipients. GMTs ranged from 180 to 2985 mMU/mL in HIV-positive participants and from 17 to 170 mMU/mL in SOT recipients, depending on the HPV type. Injection-site AEs occurred in 62% of participants but were mostly mild or moderate in intensity. None of the reported serious adverse events were deemed vaccine related. No patients died during the study.

Conclusions

Immunogenicity of the 9vHPV vaccine is high in persons living with HIV but suboptimal in SOT recipients. The vaccine is safe and well tolerated in both groups.
Patient with valvular disease: evolving care patterns
Authors: Lurz Philipp , Senni Michele , Guérin Patrice
Published: December 2020

COVID-19 has put each and every one at test. Cardiological clinics are facing constrained resources, limiting timely treatment of patients as usual. Patients with valvular heart disease are one of the most time sensitive patient populations, with delayed therapy possible leading to increased morbidity and mortality. Identifying and allocating the available resources to the most vulnerable patients is crucial in providing optimal patient care with prioritization of essential surgical or percutaneous procedures for valvular heart disease. Implementing telemedicine approaches might help to minimize non-essential physician-to-patient contact to ensure safety, for both patients and lastly but not least the treating physicians.
Left atrial appendage occlusion in COVID-19 times
Authors: Freixa Xavier , Aminian Adel , De Backer Ole , Berti Sergio , Nielsen-Kudsk Jens-Erik
Published: December 2020

The coronavirus disease 2019 pandemic is having a major impact on healthcare systems worldwide. Several months after the COVID-19 outbreak, waiting lists of non-urgent structural heart (SH) interventions continue to increase. Limitations in terms of ICU beds and anesthesiology represent a major limitation to conduct non-urgent SH interventions and are a valid reason to move towards less invasive approaches. The field of left atrial appendage occlusion (LAAO) reflects this challenging situation perfectly. The aim of this paper is to describe the possibilities for pre-procedural LAA assessment, performance of the LAAO procedure and post-procedural surveillance in these challenging times.