Applications of Shell-Model Techniques to N = 50 Nuclei.

NASA Astrophysics Data System (ADS)

Ji, Xiangdong

Traditional shell-model techniques, which involve setting up and diagonalizing model Hamiltonians in a finite Hilbert space, have been used to treat the N = 50 isotones. A model space with active f_{5over 2}, p_{3over 2}, p_{1over 2} and g_{9over 2} proton orbits is used to simulate the low-lying excitations of these isotones. An effective Hamiltonian which consists of one-body and two-body interactions is obtained by varying a total of 69 parameters to fit over 140 experimental energy levels in nuclei ranging from ^{82 }Ge to ^{96}Pd. The structures of the model wavefunctions calculated with the empirical model Hamiltonian are analyzed and compared with experimental measurements. It is found that the overall level systematics of N = 50 nuclei are well described by the model treatment. In particular, for the nuclei heavier than ^{88}Sr, the present results are not essentially different from those obtained in the p_{1over 2}-g_ {9over 2} model space, and for those lighter than ^{88}Sr, the wavefunctions are dominated by f_{5 over 2}-p_{3over 2}-p _{1over2} configurations. The model predictions for very proton-deficient, very unstable nuclei are presented for further experimental verification. Spectroscopic factors for single-proton-transfer reactions and M1 and E2 transition rates and moments are calculated using these model wavefunctions. Effective strengths of electromagnetic operators are adjusted in order to achieve the best agreement between the model predictions and experimental data. The effective proton charge is determined to be 1.9 e. The spin g-factor is found to be quenched by 16 percent for the fp shell orbits and by 29 percent for the g_{9over 2 } orbit. A new shell-model code which is capable of performing shell-model calculations in a general LS -coupling basis has been constructed. The code can be implemented with shell-model truncation schemes for both the LS -coupling limit and the seniority limit. Examples from the Ni isotopes are used to

Projected shell model description of N = 114 superdeformed isotone nuclei

NASA Astrophysics Data System (ADS)

Guo, R. S.; Chen, L. M.; Chou, C. H.

2006-03-01

A systematic description of the yrast superdeformed (SD) bands in N = 114, Z = 80-84 isotone nuclei using the projected shell model is presented. The calculated γ-ray energies, moment of inertia and M1 transitions are compared with the data for which spin is assigned. Excellent agreement with the available data for all isotones is obtained. The calculated electromagnetic properties provide a microscopic understanding of those measured nuclei. Some predictions in superdeformed nuclei are also discussed.

Microscopic description of quadrupole collectivity in neutron-rich nuclei across the N = 126 shell closure

NASA Astrophysics Data System (ADS)

Rodríguez-Guzmán, R.; Robledo, L. M.; Sharma, M. M.

2015-06-01

The quadrupole collectivity in Nd, Sm, Gd, Dy, Er, Yb, Hf and W nuclei with neutron numbers 122 ≤ N ≤ 156 is studied, both at the mean field level and beyond, using the Gogny energy density functional. Besides the robustness of the N = 126 neutron shell closure, it is shown that the onset of static deformations in those isotopic chains with increasing neutron number leads to an enhanced stability and further extends the corresponding two-neutron drip lines far beyond what could be expected from spherical calculations. Independence of the mean-field predictions with respect to the particular version of the Gogny energy density functional employed is demonstrated by comparing results based on the D1S and D1M parameter sets. Correlations beyond mean field are taken into account in the framework of the angular momentum projected generator coordinate method calculation. It is shown that N = 126 remains a robust neutron magic number when dynamical effects are included. The analysis of the collective wave functions, average deformations and excitation energies indicate that, with increasing neutron number, the zero-point quantum corrections lead to dominant prolate configurations in the 0{1/+}, 0{2/+}, 2{1/+} and 2{2/+} states of the studied nuclei. Moreover, those dynamical deformation effects provide an enhanced stability that further supports the mean-field predictions, corroborating a shift of the r-process path to higher neutron numbers. Beyond mean-field calculations provide a smaller shell gap at N = 126 than the mean-field one in good agreement with previous theoretical studies. However, the shell gap still remains strong enough in the two-neutron drip lines.

Shell Corrections Stabilizing Superheavy Nuclei and Semi-spheroidal Atomic Clusters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poenaru, Dorin N.

2008-01-24

The macroscopic-microscopic method is used to illustrate the shell effect stabilizing superheavy nuclei and to study the stability of semi-spheroidal clusters deposited on planar surfaces. The alpha decay of superheavy nuclei is calculated using three models: the analytical superasymmetric fission model; the universal curve, and the semiempirical formula taking into account the shell effects. Analytical relationships are obtained for the energy levels of the new semi-spheroidal harmonic oscillator (SSHO) single-particle model and for the surface and curvature energies of the semi-spheroidal clusters. The maximum degeneracy of the SSHO is reached at a super-deformed prolate shape for which the minimum ofmore » the liquid drop model energy is also attained.« less

Projected shell model study on nuclei near the N = Z line

NASA Astrophysics Data System (ADS)

Sun, Y.

2003-04-01

Study of the N ≈ Z nuclei in the mass-80 region is not only interesting due to the existence of abundant nuclear-structure phenomena, but also important in understanding the nucleosynthesis in the rp-process. It is difficult to apply a conventional shell model due to the necessary involvement of the g 9/2 sub-shell. In this paper, the projected shell model is introduced to this study. Calculations are systematically performed for the collective levels as well as the quasi-particle excitations. It is demonstrated that calculations with this truncation scheme can achieve a comparable quality as the large-scale shell model diagonalizations for 48 Cr, but the present method can be applied to much heavier mass regions. While the known experimental data of the yrast bands in the N ≈ Z nuclei (from Se to Ru) are reasonably described, the present calculations predict the existence of high- K states, some of which lie low in energy under certain structure conditions.

Gamow-Teller Strength Distributions for pf-shell Nuclei and its Implications in Astrophysics

NASA Astrophysics Data System (ADS)

Rahman, M.-U.; Nabi, J.-U.

2009-08-01

The {pf}-shell nuclei are present in abundance in the pre-supernova and supernova phases and these nuclei are considered to play an important role in the dynamics of core collapse supernovae. The B(GT) values are calculated for the {pf}-shell nuclei 55Co and 57Zn using the pn-QRPA theory. The calculated B(GT) strengths have differences with earlier reported shell model calculations, however, the results are in good agreement with the experimental data. These B(GT) strengths are used in the calculations of weak decay rates which play a decisive role in the core-collapse supernovae dynamics and nucleosynthesis. Unlike previous calculations the so-called Brink's hypothesis is not assumed in the present calculation which leads to a more realistic estimate of weak decay rates. The electron capture rates are calculated over wide grid of temperature ({0.01} × 109 - 30 × 109 K) and density (10-1011 g-cm-3). Our rates are enhanced compared to the reported shell model rates. This enhancement is attributed partly to the liberty of selecting a huge model space, allowing consideration of many more excited states in the present electron capture rates calculations.

Symplectic no-core shell-model approach to intermediate-mass nuclei

NASA Astrophysics Data System (ADS)

Tobin, G. K.; Ferriss, M. C.; Launey, K. D.; Dytrych, T.; Draayer, J. P.; Dreyfuss, A. C.; Bahri, C.

2014-03-01

We present a microscopic description of nuclei in the intermediate-mass region, including the proximity to the proton drip line, based on a no-core shell model with a schematic many-nucleon long-range interaction with no parameter adjustments. The outcome confirms the essential role played by the symplectic symmetry to inform the interaction and the winnowing of shell-model spaces. We show that it is imperative that model spaces be expanded well beyond the current limits up through 15 major shells to accommodate particle excitations, which appear critical to highly deformed spatial structures and the convergence of associated observables.

Shell model description of heavy nuclei and abnormal collective motions

NASA Astrophysics Data System (ADS)

Qi, Chong

2018-05-01

In this contribution I present systematic calculations on the spectroscopy and electromagnetic transition properties of intermediate-mass and heavy nuclei around 100Sn and 208Pb. We employed the large-scale configuration interaction shell model approach with realistic interactions. Those nuclei are the longest isotopic chains that can be studied by the nuclear shell model. I will show that the yrast spectra of Te isotopes show a vibrational-like equally spaced pattern but the few known E2 transitions show rotational-like behaviour. These kinds of abnormal collective behaviors cannot be reproduced by standard collective models and provide excellent background to study the competition of single-particle and various collective degrees of freedom. Moreover, the calculated B(E2) values for neutron-deficient and heavier Te isotopes show contrasting different behaviours along the yrast line, which may be related to the enhanced neutron-proton correlation when approaching N=50. The deviations between theory and experiment concerning the energies and E2 transition properties of low-lying 0+ and 2+ excited states and isomeric states in those nuclei may provide a constraint on our understanding of nuclear deformation and intruder configuration in that region.

Facile Synthesis of 1D/2D Core-Shell Structured Sb2S3@MoS2 Nanorods with Enhanced Photocatalytic Performance

NASA Astrophysics Data System (ADS)

Xu, Meilan; Zhao, Jiachang

2018-07-01

Herein, a novel core-shell heterojunction structure of molybdenum disulfide (MoS2) nanosheets coated antimony trisulfide (Sb2S3) nanorods (Sb2S3@MoS2) are designed and fabricated by a two-step hydrothermal method. The Sb2S3@MoS2 heterostructure consists of one-dimension (1D) Sb2S3 nanorods coated by two-dimension (2D) MoS2 nanosheets. When utilized as a photocatalyst under simulated sunlight, compared with pure Sb2S3 nanorods and MoS2 nanosheets, Sb2S3@MoS2 nanorods perform an enhanced photoactivity in degrading Rhodamine B (RhB) with a decomposition efficiency of 99%. The excellent photocatalytic property is attributed to the properly constructed heterojunction between Sb2S3 and MoS2, which can broaden the photoadsorption range. Furthermore, not only can the unique hybrid 1D/2D core-shell structures possess more reaction active sites, but also the compact interfaces between Sb2S3 and MoS2 provide rapid charge transfer channels for charge separation.

Shell-model method for Gamow-Teller transitions in heavy deformed odd-mass nuclei

NASA Astrophysics Data System (ADS)

Wang, Long-Jun; Sun, Yang; Ghorui, Surja K.

2018-04-01

A shell-model method for calculating Gamow-Teller (GT) transition rates in heavy deformed odd-mass nuclei is presented. The method is developed within the framework of the projected shell model. To implement the computation requirement when many multi-quasiparticle configurations are included in the basis, a numerical advancement based on the Pfaffian formula is introduced. With this new many-body technique, it becomes feasible to perform state-by-state calculations for the GT nuclear matrix elements of β -decay and electron-capture processes, including those at high excitation energies in heavy nuclei which are usually deformed. The first results, β- decays of the well-deformed A =153 neutron-rich nuclei, are shown as the example. The known log(f t ) data corresponding to the B (GT- ) decay rates of the ground state of 153Nd to the low-lying states of 153Pm are well described. It is further shown that the B (GT) distributions can have a strong dependence on the detailed microscopic structure of relevant states of both the parent and daughter nuclei.

Coulomb Excitation of n-rich nuclei along the N = 50 shell closure

NASA Astrophysics Data System (ADS)

Padilla-Rodal, E.; Galindo-Uribarri, A.; Batchelder, J. C.; Beene, J. R.; Bingham, C.; Brown, B. A.; Lagergren, K. B.; Mueller, P. E.; Radford, D. C.; Stracener, D. W.; Urrego-Blanco, J. P.; Varner, R. L.; Yu, C.-H.

2008-04-01

Recently, we have been investigating characteristics of nuclear states around the neutron-rich mass A=80 region [1]. Using the Radioactive Ion Beams (RIBs) produced at HRIBF, we have successfully measured the B(E2) values for ^78,80,82Ge , using Coulomb excitation in inverse kinematics. For the germanium isotopes, these data allow a study of the systematic trend between the subshell N= 40 and the N=50 shell. Using the same technique, we have measured the B(E2) value of various nuclei along the N=50 shell including the radioactive nucleus ^84Se. This value together with our previously measured ^82Ge, and the recent result on ^80Zn from ISOLDE [2] are providing basic experimental information needed for a better understanding of the neutron-rich nuclei around A˜80. We report the new results and compare with shell model calculations. [1] E. Padilla-Rodal et al., Phys. Rev. Lett. 94 (2005) 122501. [2] J. Van de Walle et al., Phys. Rev. Lett. 99 (2007) 142501.

Large-scale shell-model calculation with core excitations for neutron-rich nuclei beyond 132Sn

NASA Astrophysics Data System (ADS)

Jin, Hua; Hasegawa, Munetake; Tazaki, Shigeru; Kaneko, Kazunari; Sun, Yang

2011-10-01

The structure of neutron-rich nuclei with a few nucleons beyond 132Sn is investigated by means of large-scale shell-model calculations. For a considerably large model space, including neutron core excitations, a new effective interaction is determined by employing the extended pairing-plus-quadrupole model with monopole corrections. The model provides a systematical description for energy levels of A=133-135 nuclei up to high spins and reproduces available data of electromagnetic transitions. The structure of these nuclei is analyzed in detail, with emphasis of effects associated with core excitations. The results show evidence of hexadecupole correlation in addition to octupole correlation in this mass region. The suggested feature of magnetic rotation in 135Te occurs in the present shell-model calculation.

Physics of Unstable Nuclei

NASA Astrophysics Data System (ADS)

Khoa, Dao Tien; Egelhof, Peter; Gales, Sydney; Giai, Nguyen Van; Motobayashi, Tohru

2008-04-01

Studies at the RIKEN RI beam factory / T. Motobayashi -- Dilute nuclear states / M. Freer -- Studies of exotic systems using transfer reactions at GANIL / D. Beaumel et al. -- First results from the Magnex large-acceptance spectrometer / A. Cunsolo et al. -- The ICHOR project and spin-isospin physics with unstable beams / H. Sakai -- Structure and low-lying states of the [symbol]He exotic nucleus via direct reactions on proton / V. Lapoux et al. -- Shell gap below [symbol]Sn based on the excited states in [symbol]Cd and [symbol]In / M. Górska -- Heavy neutron-rich nuclei produced in the fragmentation of a [symbol]Pb beam / Zs. Podolyák et al. -- Breakup and incomplete fusion in reactions of weakly-bound nuclei / D.J. Hinde et al. -- Excited states of [symbol]B and [symbol]He and their cluster aspect / Y. Kanada-En'yo et al. -- Nuclear reactions with weakly-bound systems: the treatment of the continuum / C. H. Dasso, A. Vitturi -- Dynamic evolution of three-body decaying resonances / A. S. Jensen et al. -- Prerainbow oscillations in [symbol]He scattering from the Hoyle state of [symbol]C and alpha particle condensation / S. Ohkubo, Y. Hirabayashi -- Angular dispersion behavior in heavy ion elastic scattering / Q. Wang et al. -- Microscopic optical potential in relativistic approach / Z.Yu. Ma et al. -- Exotic nuclei studied in direct reactions at low momentum transfer - recent results and future perspectives at fair / P. Egelhof -- Isotopic temperatures and symmetry energy in spectator fragmentation / M. De Napoli et al. -- Multi-channel algebraic scattering theory and the structure of exotic compound nuclei / K. Amos et al. -- Results for the first feasibility study for the EXL project at the experimental storage ring at GSI / N. Kalantar-Nayestanaki et al. -- Coulomb excitation of ISOLDE neutron-rich beams along the Z = 28 chain / P. Van Duppen -- The gamma decay of the pygmy resonance far from stability and the GDR at finite temperature / G. Benzoni et al

Systematization of α-decaying nuclei based on shell structures: The case of even-odd nuclei

NASA Astrophysics Data System (ADS)

Yarman, Tolga; Zaim, Nimet; Yarman, O.; Kholmetskii, Alexander; Arık, Metin

2017-01-01

Previously, we provided a novel systematization of α-decaying even-even nuclei starting with the classically adopted mechanism (Yarman et al., Eur. Phys. J. A 52, 140 (2016)). The decay half-life of an α-decaying nucleus was framed so that i) the α-particle is taken at the outset to be born inside the parent nucleus with a given probability, ii) where it then keeps on bouncing off of the barrier of the parent nucleus till iii) it finally tunnels through the barrier. Knowing beforehand the measured decay half-life, we have taken into consideration, as a parameter, the probability of the α-particle being first born within the parent before it is emitted. We thence developed a scaffold based on shell properties of families composed of alike even-even nuclei. Nevertheless, our model allows us to incorporate any α-decaying nuclei, and along this line, we present a follow-up systematization of even-odd nuclei, with cases of odd-even and odd-odd α-decaying nuclei pending to be considered in a separate contribution. Notwithstanding, we make an effort herein to expand our approach to investigate the effect of "pairing" ( e.g., when a number of nucleons in the given nucleus becomes an even number, instead of the initial odd number, due to the addition of at least one neutron). Our results show that "pairing", as expected, definitely increases the stability of the given nucleus.

Central depression in nuclear density and its consequences for the shell structure of superheavy nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Afanasjev, A.V.; Laboratory of Radiation Physics, Institute of Solid State Physics, University of Latvia, LV 2169 Salaspils, Miera str. 31; Frauendorf, S.

The influence of the central depression in the density distribution of spherical superheavy nuclei on the shell structure is studied within the relativistic mean-field theory. A large depression leads to the shell gaps at the proton Z=120 and neutron N=172 numbers, whereas a flatter density distribution favors N=184 and leads to the appearance of a Z=126 shell gap and to the decrease of the size of the Z=120 shell gap. The correlations between the magic shell gaps and the magnitude of the central depression are discussed for relativistic and nonrelativistic mean field theories.

A nucleon-pair and boson coexistent description of nuclei

NASA Astrophysics Data System (ADS)

Dai, Lianrong; Pan, Feng; Draayer, J. P.

2017-07-01

We study a mixture of s-bosons and like-nucleon pairs with the standard pairing interaction outside an inert core. Competition between the nucleon-pairs and s-bosons is investigated in this scenario. The robustness of the BCS-BEC coexistence and crossover phenomena are examined through an analysis of pf-shell nuclei with realistic single-particle energies, in which two configurations with Pauli blocking of nucleon-pair orbits due to the formation of the s-bosons is taken into account. When the nucleon-pair orbits are considered to be independent of the s-bosons, the BCS-BEC crossover becomes smooth, with the number of the s-bosons noticeably more than that of the nucleon-pairs near the half-shell point, a feature that is demonstrated in the pf-shell for several values of the standard pairing interaction strength. As a further test of the robustness of the BCS-BEC coexistence and crossover phenomena in nuclei, results are given for values of even-even 102-130Sn with 100Sn taken as a core and valence neutron pairs confined within the 1d 5/2, 0g 7/2, 1d 3/2, 2s 1/2, 1h 11/2 orbits in the nucleon-pair orbit and the s-boson independent approximation. The results indicate that the B(E2) values are reproduced well. Supported by National Natural Science Foundation of China (11375080, 11675071), the U.S. National Science Foundation (OCI-0904874 and ACI-1516338), U. S. Department of Energy (DE-SC0005248), the Southeastern Universities Research Association, the China-U. S. Theory Institute for Physics with Exotic Nuclei (CUSTIPEN) (DE-SC0009971), and the LSU-LNNU joint research program (9961) is acknowledged

Survey of the (. cap alpha. ,/sup 2/He) reaction on 1p- and 2s1d-shell nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jahn, R.; Stahel, D.P.; Wozniak, G.J.

A /sup 2/He detection system has been developed and used to investigate the (..cap alpha..,/sup 2/He) reaction at bombarding energies of 55 and 65 MeV on targets of /sup 12/C, /sup 13/C, /sup 14/N, /sup 15/N, /sup 16/O, /sup 18/O, /sup 20/Ne, /sup 22/Ne, /sup 24/Mg, /sup 26/Mg, /sup 28/Si, /sup 29/Si, /sup 32/S, /sup 36/Ar, /sup 38/Ar, and /sup 40/Ca. Preferential population of two-neutron states with dominant (d/sub 5/2/)/sup 2//sub 4/, (d/sub 3/2/f/sub 7/2/)/sub 5/, and (f/sub 7/2/)/sup 2//sub 6/ character was observed. A linear A dependence of the binding energies of the J/sup ..pi../ = 5/sup -/ andmore » 6/sup +/ states was obtained. This systematic behavior is well described by the Bansal-French model, using the parameters a = - 0.30 MeV and b = 2.6 MeV. Simple shell-model calculations for the 2n configurations are in good agreement with the experimental data.« less

Radii in the sd shell and the 1s 1/2 “halo” orbit: A game changer

NASA Astrophysics Data System (ADS)

Bonnard, J.; Zuker, A. P.

2018-05-01

A new microscopic parametrisation of nuclear radii as a functional of single-particle occupation numbers is presented. Its form is inspired by the Duflo-Zuker phenomenological fit which contains a “correlation” term that recently made it possible to understand the isotope shifts of several species as due to unexpectedly large 1s 1/2 and 1p orbits [Bonnard J, Lenzi S M and Zuker A P 2016 Phys. Rev. Lett. 116 212501]. It will be shown that the calculated radii for sd-shell nuclei reproduce the experimental data better than the most accurate existing fits. These results reveal a very peculiar behaviour of the 1s 1/2 orbit: It is huge (about 1.6 fm bigger than its d counterparts of about 3.5 fm) up to N, Z = 14, then drops abruptly but remains some 0.6 fm larger than the d orbits. An intriguing mechanism bound to challenge our understanding of shell formation.

Matter distribution and spin-orbit force in spherical nuclei

NASA Astrophysics Data System (ADS)

Co', G.; Anguiano, M.; De Donno, V.; Lallena, A. M.

2018-03-01

We investigate the possibility that some nuclei show density distributions with a depletion in the center, a semibubble structure, by using a Hartree-Fock plus Bardeen-Cooper-Schrieffer approach. We separately study the proton, neutron, and matter distributions in 37 spherical nuclei mainly in the s -d shell region. We found a relation between the semibubble structure and the energy splitting of spin-orbit partner single particle levels. The presence of semibubble structure reduces this splitting, and we study its consequences on the excitation spectrum of the nuclei under investigation by using a quasiparticle random-phase-approximation approach. The excitation energies of the low-lying 4+ states can be related to the presence of semibubble structure in nuclei.

Evolution of Structure in Nuclei: Meditation by Sub-Shell Modifications and Relation to Binding Energies

NASA Astrophysics Data System (ADS)

Casten, R. F.; Cakirli, R. B.

2009-03-01

Understanding the development of configuration mixing, coherence, collectivity, and deformation in nuclei is one of the crucial challenges in nuclear structure physics, and one which has become all the more important with the advent of next generation facilities for the study of exotic nuclei. We will discuss recent work on phase/shape transitional behavior in nuclei, and the role of changes in sub-shell structure in mediating such transitional regions. We will also discuss a newly found, much deeper, link between nuclear structure and nuclear binding energies.

Realistic Gamow shell model for resonance and continuum in atomic nuclei

NASA Astrophysics Data System (ADS)

Xu, F. R.; Sun, Z. H.; Wu, Q.; Hu, B. S.; Dai, S. J.

2018-02-01

The Gamow shell model can describe resonance and continuum for atomic nuclei. The model is established in the complex-moment (complex-k) plane of the Berggren coordinates in which bound, resonant and continuum states are treated on equal footing self-consistently. In the present work, the realistic nuclear force, CD Bonn, has been used. We have developed the full \\hat{Q}-box folded-diagram method to derive the realistic effective interaction in the model space which is nondegenerate and contains resonance and continuum channels. The CD-Bonn potential is renormalized using the V low-k method. With choosing 16O as the inert core, we have applied the Gamow shell model to oxygen isotopes.

Projected shell model study of odd-odd f-p-g shell proton-rich nuclei

NASA Astrophysics Data System (ADS)

Palit, R.; Sheikh, J. A.; Sun, Y.; Jain, H. C.

2003-01-01

A systematic study of two-quasiparticle bands of the proton-rich odd-odd nuclei in the mass A˜70 80 region is performed using the projected shell model approach. The study includes Br, Rb, and Y isotopes with N=Z+2 and Z+4. We describe the energy spectra and electromagnetic transition strengths in terms of the configuration mixing of the angular-momentum projected multi-quasiparticle states. Signature splitting and signature inversion in the rotational bands are discussed and are shown to be well described. A preliminary study of the odd-odd N=Z nucleus 74Rb, using the concept of spontaneous symmetry breaking is also presented.

Structure of neutron-rich nuclei around the N = 50 shell-gap closure

NASA Astrophysics Data System (ADS)

Faul, T.; Duchêne, G.; Thomas, J.-C.; Nowacki, F.; Huyse, M.; Van Duppen, P.

2010-04-01

The structure of neutron-rich nuclei in the vicinity of 78Ni have been investigated via the β-decay of 71,73,75Cu isotopes (ISOLDE, CERN). Experimental results have been compared with shell-model calculations performed with the ANTOINE code using a large (2p3/21f5/22p1/21g9/2) valence space and a 56/28Ni28 core.

Neutrino Spectra from Nuclear Weak Interactions in sd-Shell Nuclei under Astrophysical Conditions

NASA Astrophysics Data System (ADS)

Misch, G. Wendell; Sun, Yang; Fuller, George M.

2018-01-01

We present shell model calculations of nuclear neutrino energy spectra for 70 sd-shell nuclei over the mass number range A = 21–35. Our calculations include nuclear excited states as appropriate for the hot and dense conditions characteristic of pre-collapse massive stars. We consider neutrinos produced by charged lepton captures and decays, and for the first time in tabular form, neutral current nuclear deexcitation, providing neutrino energy spectra on the Fuller–Fowler–Newman temperature–density grid for these interaction channels for each nucleus. We use the full sd-shell model space to compute initial nuclear states up to 20 MeV excitation with transitions to final states up to 35–40 MeV, employing a modification of the Brink-Axel hypothesis to handle high-temperature population factors and the nuclear partition functions.

Deformed shell model results for neutrinoless double beta decay of nuclei in A = 60 - 90 region

NASA Astrophysics Data System (ADS)

Sahu, R.; Kota, V. K. B.

2015-03-01

Nuclear transition matrix elements (NTME) for the neutrinoless double beta decay (Oνββ or OνDBD) of 70Zn, 80Se and 82Se nuclei are calculated within the framework of the deformed shell model (DSM) based on Hartree-Fock (HF) states. For 70Zn, jj44b interaction in 2p3/2, 1f5/2, 2p1/2 and 1g9/2 space with 56Ni as the core is employed. However, for 80Se and 82Se nuclei, a modified Kuo interaction with the above core and model space are employed. Most of our calculations in this region were performed with this effective interaction. However, jj44b interaction has been found to be better for 70Zn. The above model space was used in many recent shell model (SM) and interacting boson model (IBM) calculations for nuclei in this region. After ensuring that DSM gives good description of the spectroscopic properties of low-lying levels in these three nuclei considered, the NTME are calculated. The deduced half-lives with these NTME, assuming neutrino mass is 1 eV, are 1.1 × 1026, 2.3 × 1027 and 2.2 × 1024 yr for 70Zn, 80Se and 82Se, respectively.

Fission and Properties of Neutron-Rich Nuclei

NASA Astrophysics Data System (ADS)

Hamilton, Joseph H.; Ramayya, A. V.; Carter, H. K.

2008-08-01

Opening session. Nuclear processes in stellar explosions / M. Wiescher. In-beam [symbol]-ray spectroscopy of neutron-rich nuclei at NSCL / A. Gade -- Nuclear structure I. Shell-model structure of neutron-rich nuclei beyond [symbol]Sn / A. Covello ... [et al.]. Shell structure and evolution of collectivity in nuclei above the [symbol]Sn core / S. Sarkar and M. S. Sarkar. Heavy-ion fusion using density-constrained TDHF / A. S. Umar and V. E. Oberacker. Towards an extended microscopic theory for upper-fp shell nuclei / K. P. Drumev. Properties of the Zr and Pb isotopes near the drip-line / V. N. Tarasov ... [et al.]. Identification of high spin states in [symbol] Cs nuclei and shell model calculations / K. Li ... [et al.]. Recent measurements of spherical and deformed isomers using the Lohengrin fission-fragment spectrometer / G. S. Simpson ... [et al.] -- Nuclear structure II. Nuclear structure investigation with rare isotope spectroscopic investigations at GSI / P. Boutachkov. Exploring the evolution of the shell structures by means of deep inelastic reactions / G. de Anaelis. Probing shell closures in neutron-rich nuclei / R. Krücken for the S277 and REX-ISOLDEMINIBALL collaborations. Structure of Fe isotopes at the limits of the pf-shell / N. Hoteling ... [et al.]. Spectroscopy of K isomers in shell-stabilized trans-fermium nuclei / S. K. Tandel ... [et al.] -- Radioactive ion beam facilities. SPIRAL2 at GANIL: a world leading ISOL facility for the next decade / S. Gales. New physics at the International Facility for Antiproton and Ion Research (FAIR) next to GSI / I. Augustin ... [et al.]. Radioactive beams from a high powered ISOL system / A. C. Shotter. RlKEN RT beam factory / T. Motobayashi. NSCL - ongoing activities and future perspectives / C. K. Gelbke. Rare isotope beams at Argonne / W. F. Henning. HRIBF: scientific highlights and future prospects / J. R. Beene. Radioactive ion beam research done in Dubna / G. M. Ter-Akopian ... [et al.] -- Fission I

Stretched proton-neutron configurations in fp-shell nuclei (II). Systematics

NASA Astrophysics Data System (ADS)

von Neumann-Cosel, P.; Fister, U.; Jahn, R.; Schenk, P.; Trelle, T. K.; Wenzel, D.; Wienands, U.

1994-03-01

The systematics of the binding energies of stretched proton-neutron configurations ( f{7}/{2}, g{9}/{2}) 8 -, ( p{3}/{2}, g{9}/{2}) 6 -, ( g{9}/{2}, p{3}/{2}) 6- and ( g{9}/{2}) 29 + are studied over a wide range of f p-shell nuclei. The effective proton-neutron interaction energies deduced from the data are nearly constant for ( p{3}/{2}, g{9}/{2}) 6 -and ( g{9}/{2}) 29 + states while the ( f{7}/{2}, g{9}/{2}) 8 - configuration reveals an additional repulsive term proportional to the partial filling of the f{7}/{2} orbit in the target ground state. Two-body matrix elements are extracted. A crude shell model, which predicts that the excitation energy of a stretched state is equal to the sum of the single-particle energies, works well for the 6 - and 9 + states, but fails for the 8 - levels due to neglect of the additional interactions described above. The physics underlying the empirically introduced basic assumptions of the crude shell model is discussed. The binding energies are found to be linearly dependent on the mass number A and the isospin Tz component and are well described by the weak-coupling model of Bansal and French. The derived parameters agree with averaged values of a similar analysis for the single-particle states in the corresponding odd-even neighbours. The data indicate a significant change of the particle-hole energies with closure of the proton f{7}/{2} shell.

Effectively-truncated large-scale shell-model calculations and nuclei around 100Sn

NASA Astrophysics Data System (ADS)

Gargano, A.; Coraggio, L.; Itaco, N.

2017-09-01

This paper presents a short overview of a procedure we have recently introduced, dubbed the double-step truncation method, which is aimed to reduce the computational complexity of large-scale shell-model calculations. Within this procedure, one starts with a realistic shell-model Hamiltonian defined in a large model space, and then, by analyzing the effective single particle energies of this Hamiltonian as a function of the number of valence protons and/or neutrons, reduced model spaces are identified containing only the single-particle orbitals relevant to the description of the spectroscopic properties of a certain class of nuclei. As a final step, new effective shell-model Hamiltonians defined within the reduced model spaces are derived by way of a unitary transformation of the original large-scale Hamiltonian. A detailed account of this transformation is given and the merit of the double-step truncation method is illustrated by discussing few selected results for 96Mo, described as four protons and four neutrons outside 88Sr. Some new preliminary results for light odd-tin isotopes from A = 101 to 107 are also reported.

Large scale shell model study of nuclear spectroscopy in nuclei around 132Sn

NASA Astrophysics Data System (ADS)

Lo Iudice, N.; Bianco, D.; Andreozzi, F.; Porrino, A.; Knapp, F.

2012-10-01

The properties of low-lying 2+ states in chains of nuclei in the proximity of the magic number N=82 are investigated within a new shell model approach exploiting an iterative algorithm alternative to Lanczos. The calculation yields levels and transition strengths in overall good agreement with experiments. The comparative analysis of the E2 and M1 transitions supports, in many cases, the scheme provided by the interacting boson model.

0ħω MEC effect on M1 properties of middle pf-shell nuclei

NASA Astrophysics Data System (ADS)

Nakada, H.; Sebe, T.

1994-09-01

M1 properties of middle pf-shell nuclei are studied within the framework of a large-scale shell-model calculation, by including two-body operators originating from the MEC effect within the 0ħω space. This MEC effect tends to enhance the M1 matrix elements slightly. However, the 0ħω MEC effect does not change the previous results so much, which have shown notable quenching in the magnetic moments of 55Co and 57Ni due to the 0ħω CP effect, while the 0ħω MEC effect should be kept track of in discussing the M1 properties with ⪅ 10% accuracy.

Spectroscopy of 70Kr and isospin symmetry in the T =1 f p g shell nuclei

NASA Astrophysics Data System (ADS)

Debenham, D. M.; Bentley, M. A.; Davies, P. J.; Haylett, T.; Jenkins, D. G.; Joshi, P.; Sinclair, L. F.; Wadsworth, R.; Ruotsalainen, P.; Henderson, J.; Kaneko, K.; Auranen, K.; Badran, H.; Grahn, T.; Greenlees, P.; HerzaáÅ, A.; Jakobsson, U.; Konki, J.; Julin, R.; Juutinen, S.; Leino, M.; Sorri, J.; Pakarinen, J.; Papadakis, P.; Peura, P.; Partanen, J.; Rahkila, P.; Sandzelius, M.; Sarén, J.; Scholey, C.; Stolze, S.; Uusitalo, J.; David, H. M.; de Angelis, G.; Korten, W.; Lotay, G.; Mallaburn, M.; Sahin, E.

2016-11-01

The recoil-β tagging technique has been used in conjunction with the 40Ca(32S,2 n ) reaction at a beam energy of 88 MeV to identify transitions associated with the decay of the 2+ and, tentatively, 4+ states in the nucleus 70Kr. These data are used, along with previously published data, to examine the triplet energy differences (TED) for the mass 70 isobars. The experimental TED values are compared with shell model calculations, performed with the JUN45 interaction in the f p g model space, that include a J =0 isospin nonconserving (INC) interaction with an isotensor strength of 100 keV. The agreement is found to be very good up to spin 4 and supports the expectation for analog states that all three nuclei have the same oblate shape at low-spin. The A =70 results are compared with the experimental and shell model predicted TED and mirror energy differences (MED) for the mass 66 and 74 systems. The comparisons clearly demonstrate the importance of the isotensor INC interaction in replicating the TED data in this region. Issues related to the observed MED values and their interpretation within the shell model are discussed.

Intermediate-energy inverse-kinematics one-proton pickup reactions on neutron-deficient fp-shell nuclei

NASA Astrophysics Data System (ADS)

McDaniel, S.; Gade, A.; Tostevin, J. A.; Baugher, T.; Bazin, D.; Brown, B. A.; Cook, J. M.; Glasmacher, T.; Grinyer, G. F.; Ratkiewicz, A.; Weisshaar, D.

2012-01-01

Background: Thick-target-induced nucleon-adding transfer reactions onto energetic rare-isotope beams are an emerging spectroscopic tool. Their sensitivity to single-particle structure complements one-nucleon removal reaction capabilities in the quest to reveal the evolution of nuclear shell structure in very exotic nuclei. Purpose: Our purpose is to add intermediate-energy, carbon-target-induced one-proton pickup reactions to the arsenal of γ-ray-tagged direct reactions applicable in the regime of low beam intensities and to apply these for the first time to fp-shell nuclei. Methods: Inclusive and partial cross sections were measured for the 12C(48Cr,49Mn+γ)X and 12C(50Fe,51Co+γ)X proton pickup reactions at 56.7 and 61.2 MeV/nucleon, respectively, using coincident particle-γ spectroscopy at the National Superconducting Cyclotron Laboratory. The results are compared to reaction theory calculations using fp-shell-model nuclear structure input. For comparison with our previous work, the same reactions were measured on 9Be targets. Results: The measured partial cross sections confirm the specific population pattern predicted by theory, with pickup into high-ℓ orbitals being strongly favored, driven by linear and angular momentum matching. Conclusion: Carbon-target-induced pickup reactions are well suited, in the regime of modest beam intensity, to study the evolution of nuclear structure, with specific sensitivities that are well described by theory.

Mirror energy difference and the structure of loosely bound proton-rich nuclei around A =20

NASA Astrophysics Data System (ADS)

Yuan, Cenxi; Qi, Chong; Xu, Furong; Suzuki, Toshio; Otsuka, Takaharu

2014-04-01

The properties of loosely bound proton-rich nuclei around A =20 are investigated within the framework of the nuclear shell model. In these nuclei, the strength of the effective interactions involving the loosely bound proton s1/2 orbit is significantly reduced in comparison with that of those in their mirror nuclei. We evaluate the reduction of the effective interaction by calculating the monopole-based-universal interaction (VMU) in the Woods-Saxon basis. The shell-model Hamiltonian in the sd shell, such as USD, can thus be modified to reproduce the binding energies and energy levels of the weakly bound proton-rich nuclei around A =20. The effect of the reduction of the effective interaction on the structure and decay properties of these nuclei is also discussed.

Ordering of the 0 d5 /2 and 1 s1 /2 proton levels in light nuclei

NASA Astrophysics Data System (ADS)

Hoffman, C. R.; Kay, B. P.; Schiffer, J. P.

2016-08-01

A survey of the available single-proton data in A ≤17 nuclei was completed. These data, along with calculations using a Woods-Saxon potential, show that the ordering of the 0 d5 /2 and 1 s1 /2 proton orbitals are determined primarily by the proximity of the s -state proton energy to the Coulomb barrier. This is analogous to the dependence of the corresponding neutron orbitals in proximity to the neutron threshold, which was previously discussed.

Production of n-rich Nuclei along the Closed Shell N=126 in the collision 136Xe + 208Pb @E lab =870 MeV

NASA Astrophysics Data System (ADS)

Quero, D.; Vardaci, E.; Kozulin, E. M.; Zagrebaev, V. A.; Corradi, L.; Pulcini, A.; La Rana, G.; Itkis, I. M.; Knyazheva, G. N.; Novikov, K.; Harca, I.; Fioretto, E.; Stefanini, A. M.; Montanari, D.; Montagnoli, G.; Scarlassara, F.; Szilner, S.; Mijatović, T.; Trzaska, W. H.

2018-05-01

Multi-nucleon transfer reactions are nowadays the only known mean to produce neutron-rich nuclei in the Terra Incognita. The closed-shell region N=126 is crucial for both studying shell-quenching in exotic nuclei and the r-process, being its last “waiting-point”. The choice of suitable reactions is challenging and a favorable case is 136Xe+208Pb, near the Coulomb barrier, because their neutron shell-closures play a stabilizing role, favoring the proton-transfer from lead to xenon. TOF-TOF data were analyzed to reconstruct the mass-energy distribution of the primary fragments. Preliminary results of an experiment held at Laboratori Nazionali di Legnaro with PRISMA, aimed at A and Z identification of the products, will be shown.

Systematization of α-decaying nuclei based on shell structures: The case of odd-even and odd-odd nuclei

NASA Astrophysics Data System (ADS)

Yarman, Tolga; Zaim, Nimet; Yarman, Ozan; Kholmetskii, Alexander; Arık, Metin

In previous studies, we provided a novel systematization of α-decaying even-even and even-odd nuclei starting with the classically adopted mechanism [T. Yarman et al., Eur. Phys. J. A 52 (2016) 140; Eur. Phys. J. A 53 (2017) 4]. Knowing beforehand the measured decay half-life, we had taken as a parameter the probability of the α-particle as being first born in a unit period of time, within the parent nucleus before it is emitted out. We thence developed a scaffold based on shell properties of families composed of “alike nuclei”. Along the same line, we now present a systematization of odd-even (OE) as well as odd-odd (OO) nuclei. We apply our approach further to the investigation of the effect of pairing (e.g., the effect when the number of nucleons is increased by one neutron), and that of unpairing (e.g., the effect when the number of nucleons is decreased by one neutron); thus it becomes an even number for the case of odd-even nuclei (Case OE), and an odd number in the case of odd-odd nuclei (Case OO). For the first case (OE), we pick the exemplar set 161Re, 217Fr, 243Bk, 263Db; where we delineate by, respectively, Re, Fr, Bk, and Db all of the odd-even or odd-odd isotopes that neighbor the four mentioned odd-even isotopes on the proposed scaffold. We proceed in the same way for the second case (OO). Thus, we choose the exemplar set of odd-odd nuclei 172Ir, 218Ac, 244Es. We then gather all of the Ir, Ac, and Es odd-odd and odd-even isotopes that neighbor the three mentioned odd-odd isotopes on the proposed scaffold. We show that, in the former case, pairing, as expected, generally increases stability of the given nucleus; and in the latter case, unpairing works in just the opposite direction — i.e., it generally increases instability. We disclose “stability peaks” versus Z for both sets of nuclei, we tackle here. Furthermore, we present a study to highlight an outlook of “odd-A nuclei” at hand. Contrary to the general expectation, we unveil no

Evolution of collectivity near mid-shell from excited-state lifetime measurements in rare earth nuclei

NASA Astrophysics Data System (ADS)

Werner, V.; Cooper, N.; Régis, J.-M.; Rudigier, M.; Williams, E.; Jolie, J.; Cakirli, R. B.; Casten, R. F.; Ahn, T.; Anagnostatou, V.; Berant, Z.; Bonett-Matiz, M.; Elvers, M.; Heinz, A.; Ilie, G.; Radeck, D.; Savran, D.; Smith, M. K.

2016-03-01

The B (E 2 ) excitation strength of the first excited 2+ state in even-even nuclei should directly correlate with the size of the valence space and maximize at mid-shell. A previously found saturation of B (E 2 ) strengths in well-deformed rotors at mid-shell is tested through high-precision measurements of the lifetimes of the lowest-lying 2+ states of the 168Hf and 174W rare earth isotopes. Measurements were performed using fast LaBr3 scintillation detectors. Combined with the recently remeasured B (E 2 ;21+→01+) values for Hf and W isotopes the new data remove discrepancies observed in the differentials of B (E 2 ) values for these isotopes.

Ab initio treatment of fully open-shell medium-mass nuclei with the IM-SRG

NASA Astrophysics Data System (ADS)

Stroberg, Ragnar; Calci, Angelo; Holt, Jason; Navratil, Petr; Bogner, Scott; Hergert, Heiko; Roth, Robert; Schwenk, Achim

2016-09-01

The in-medium similarity renormalization group (IM-SRG) is a recently-developed theoretical many-body framework which - like the coupled cluster and the self-consistent Green's function approaches - allows for the treatment of medium-mass nuclei using interactions fit at the few-body level. I will give a brief overview of how the IM-SRG may be used to decouple a shell-model type valence space. I will then describe a recent development for the approximate treatment of residual 3N forces in the valence space which extends the reach of IM-SRG to essentially all medium-mass nuclei, and I will present some selected results spanning isotopic chains from beryllium (Z=4) to nickel (Z=28). Finally, I will discuss the consistent treatment of transition operators, highlighting the potential for future applications in electroweak physics.

Gamma ray heating and neutrino cooling rates due to weak interaction processes on sd-shell nuclei in stellar cores

NASA Astrophysics Data System (ADS)

Fayaz, Muhammad; Nabi, Jameel-Un; Majid, Muhammad

2017-07-01

Gamma ray heating and neutrino cooling rates, due to weak interaction processes, on sd-shell nuclei in stellar core are calculated using the proton neutron quasiparticle random phase approximation theory. The recent extensive experimental mass compilation of Wang et al. (Chin. Phys. C 36:1603, 2012), other improved model input parameters including nuclear quadrupole deformation (Raman et al. in At. Data Nucl. Data Tables 78(1):1-128, 2001; Möller et al. in At. Data Nucl. Data Tables 109:1-204, 2016) and physical constants are taken into account in the current calculation. The purpose of this work is two fold, one is to improve the earlier calculation of weak rates performed by Nabi and Klapdor-Kleingrothaus (At. Data Nucl. Data Tables 71:149, 1999a) using the same theory. We further compare our results with previous calculations. The selected sd-shell nuclei, considered in this work, are of special interest for the evolution of O-Ne-Mg core in 8-10 M_{⊙} stars due to competitive gamma ray heating rates and cooling by URCA processes. The outcome of these competitions is to determine, whether the stars end up as a white dwarf (Nabi in Phys. Rev. C 78(4):045801, 2008b), an electron-capture supernova (Jones et al. in Astrophys. J. 772(2):150, 2013) or Fe core-collapse supernova (Suzuki et al. in Astrophys. J. 817(2):163, 2016). The selected sd-shell nuclei for calculation of associated weak-interaction rates include ^{20,23}O, ^{20,23}F, ^{20,23,24}Ne, {}^{20,23-25}Na, and {}^{23-25}Mg. The cooling and heating rates are calculated for density range (10 ≤ ρ (g cm^{-3}) ≤ 10^{11}) and temperature range (0.01× 109≤ T(K)≤ 30× 109). The calculated gamma heating rates are orders of magnitude bigger than the shell model rates (except for ^{25}Mg at low densities). At high temperatures the gamma heating rates are in reasonable agreement. The calculated cooling rates are up to an order of magnitude bigger for odd-A nuclei.

Structure of p-shell nuclei using three-nucleon interactions evolved with the similarity renormalization group

DOE PAGES

Jurgenson, E. D.; Maris, P.; Furnstahl, R. J.; ...

2013-05-13

The similarity renormalization group (SRG) is used to soften interactions for ab initio nuclear structure calculations by decoupling low- and high-energy Hamiltonian matrix elements. The substantial contribution of both initial and SRG-induced three-nucleon forces requires their consistent evolution in a three-particle basis space before applying them to larger nuclei. While, in principle, the evolved Hamiltonians are unitarily equivalent, in practice the need for basis truncation introduces deviations, which must be monitored. Here we present benchmark no-core full configuration calculations with SRG-evolved interactions in p-shell nuclei over a wide range of softening. As a result, these calculations are used to assessmore » convergence properties, extrapolation techniques, and the dependence of energies, including four-body contributions, on the SRG resolution scale.« less

First Determination of the Level Structure of an s d -Shell Hypernucleus, F19Λ

NASA Astrophysics Data System (ADS)

Yang, S. B.; Ahn, J. K.; Akazawa, Y.; Aoki, K.; Chiga, N.; Ekawa, H.; Evtoukhovitch, P.; Feliciello, A.; Fujita, M.; Hasegawa, S.; Hayakawa, S.; Hayakawa, T.; Honda, R.; Hosomi, K.; Hwang, S. H.; Ichige, N.; Ichikawa, Y.; Ikeda, M.; Imai, K.; Ishimoto, S.; Kanatsuki, S.; Kim, S. H.; Kinbara, S.; Kobayashi, K.; Koike, T.; Lee, J. Y.; Miwa, K.; Moon, T. J.; Nagae, T.; Nakada, Y.; Nakagawa, M.; Ogura, Y.; Sakaguchi, A.; Sako, H.; Sasaki, Y.; Sato, S.; Shirotori, K.; Sugimura, H.; Suto, S.; Suzuki, S.; Takahashi, T.; Tamura, H.; Tanida, K.; Togawa, Y.; Tsamalaidze, Z.; Ukai, M.; Wang, T. F.; Yamamoto, T. O.; J-PARC E13 Collaboration

2018-03-01

We report on the first observation of γ rays emitted from an s d -shell hypernucleus, F19Λ . The energy spacing between the ground state doublet, 1 /2+ and 3 /2+ states, of F19Λ is determined to be 315.5 ±0.4 (stat )-0.5+0.6(syst ) keV by measuring the γ -ray energy of the M 1 (3 /2+→1 /2+) transition. In addition, three γ -ray peaks are observed and assigned as E 2 (5 /2+→1 /2+), E 1 (1 /2-→1 /2+), and E 1 (1 /2-→3 /2+) transitions. The excitation energies of the 5 /2+ and 1 /2- states are determined to be 895.2 ±0.3 (stat )±0.5 (syst ) and 1265.6 ±1.2 (stat )-0.5+0.7(syst ) keV , respectively. It is found that the ground state doublet spacing is well described by theoretical models based on existing s - and p -shell hypernuclear data.

Approximate symmetries in atomic nuclei from a large-scale shell-model perspective

NASA Astrophysics Data System (ADS)

Launey, K. D.; Draayer, J. P.; Dytrych, T.; Sun, G.-H.; Dong, S.-H.

2015-05-01

In this paper, we review recent developments that aim to achieve further understanding of the structure of atomic nuclei, by capitalizing on exact symmetries as well as approximate symmetries found to dominate low-lying nuclear states. The findings confirm the essential role played by the Sp(3, ℝ) symplectic symmetry to inform the interaction and the relevant model spaces in nuclear modeling. The significance of the Sp(3, ℝ) symmetry for a description of a quantum system of strongly interacting particles naturally emerges from the physical relevance of its generators, which directly relate to particle momentum and position coordinates, and represent important observables, such as, the many-particle kinetic energy, the monopole operator, the quadrupole moment and the angular momentum. We show that it is imperative that shell-model spaces be expanded well beyond the current limits to accommodate particle excitations that appear critical to enhanced collectivity in heavier systems and to highly-deformed spatial structures, exemplified by the second 0+ state in 12C (the challenging Hoyle state) and 8Be. While such states are presently inaccessible by large-scale no-core shell models, symmetry-based considerations are found to be essential.

Resource Letter NSM-1: New insights into the nuclear shell model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dean, David Jarvis; Hamilton, J. H.

2011-01-01

This Resource Letter provides a guide to the literature on the spherical shell model as applied to nuclei. The nuclear shell model describes the structure of nuclei starting with a nuclear core developed by the classical neutron and proton magic numbers N,Z=2,8,20,28,50,82, 126, where gaps occur in the single-particle energies as a shell is filled, and the interactions of valence nucleons that reside beyond that core. Various modern extensions of this model for spherical nuclei are likewise described. Significant extensions of the nuclear shell model include new magic numbers for spherical nuclei and now for deformed nuclei as well. Whenmore » both protons and neutrons have shell gaps at the same spherical or deformed shapes, they can reinforce each other to give added stability to that shape and lead to new magic numbers. The vanishings of the classical spherical shell model energy gaps and magic numbers in new neutron-rich nuclei are described. Spherical and deformed shell gaps are seen to be critical for the existence of elements with Z > 100.« less

Nuclear Data Evaluation for Mass Chain A=217:Odd-Proton Nuclei

PubMed Central

Nafee, Sherif S.; Shaheen, Salem A.; Al-Ramady, Amir M.

2016-01-01

Thallium (Tl81217), Bismuth (Bi83217), Astatine (At85217), Francium (Fr87217), Actinium (Ac89217) and Protactinium (Pa91217) are of odd-proton numbers among the mass chain A = 217. In the present work, the half-lives and gamma transitions for the six nuclei have been studied and adopted based on the recently published interactions or unevaluated nuclear data sets XUNDL. The Q (α) has been updated based on the recent published work of the Atomic Mass Evaluation AME2012 as well. Moreover, the total conversion electrons as well as the K-Shell to L-Shell, L-Shell to M-Shell and L-Shell to N-Shell Conversion Electron Ratios have been calculated using BrIcc code v2.3. An updated skeleton decay scheme for each of the above nuclei has been presented here. The decay hindrance factors (HF) calculated using the ALPHAD program, which is available from Brookhaven National Laboratory’s website, have been calculated for the α- decay data sets for 221Fr-, 221Ac- and 221Pa- α-decays. PMID:26761207

Large scale shell model study of the evolution of mixed-symmetry states in chains of nuclei around 132Sn

NASA Astrophysics Data System (ADS)

Lo Iudice, N.; Bianco, D.; Andreozzi, F.; Porrino, A.; Knapp, F.

2012-10-01

Large scale shell model calculations based on a new diagonalization algorithm are performed in order to investigate the mixed symmetry states in chains of nuclei in the proximity of N=82. The resulting spectra and transitions are in agreement with the experiments and consistent with the scheme provided by the interacting boson model.

Structure models: From shell model to ab initio methods. A brief introduction to microscopic theories for exotic nuclei

NASA Astrophysics Data System (ADS)

Bacca, Sonia

2016-04-01

A brief review of models to describe nuclear structure and reactions properties is presented, starting from the historical shell model picture and encompassing modern ab initio approaches. A selection of recent theoretical results on observables for exotic light and medium-mass nuclei is shown. Emphasis is given to the comparison with experiment and to what can be learned about three-body forces and continuum properties.

Computational efficient segmentation of cell nuclei in 2D and 3D fluorescent micrographs

NASA Astrophysics Data System (ADS)

De Vylder, Jonas; Philips, Wilfried

2011-02-01

This paper proposes a new segmentation technique developed for the segmentation of cell nuclei in both 2D and 3D fluorescent micrographs. The proposed method can deal with both blurred edges as with touching nuclei. Using a dual scan line algorithm its both memory as computational efficient, making it interesting for the analysis of images coming from high throughput systems or the analysis of 3D microscopic images. Experiments show good results, i.e. recall of over 0.98.

On Closed Shells in Nuclei

DOE R&D Accomplishments Database

Mayer, M. G.

1948-02-01

It has been suggested in the past that special numbers of neutrons or protons in the nucleus form a particularly stable configuration.{sup1} The complete evidence for this has never been summarized, nor is it generally recognized how convincing this evidence is. That 20 neutrons or protons (Ca{sup40}) form a closed shell is predicted by the Hartree model. A number of calculations support this fact.{sup2} These considerations will not be repeated here. In this paper, the experimental facts indicating a particular stability of shells of 50 and 82 protons and of 50, 82, and 126 neutrons will be listed.

Facile synthesis of 3D few-layered MoS2 coated TiO2 nanosheet core-shell nanostructures for stable and high-performance lithium-ion batteries

NASA Astrophysics Data System (ADS)

Chen, Biao; Zhao, Naiqin; Guo, Lichao; He, Fang; Shi, Chunsheng; He, Chunnian; Li, Jiajun; Liu, Enzuo

2015-07-01

Uniform transition metal sulfide deposition on a smooth TiO2 surface to form a coating structure is a well-known challenge, caused mainly due to their poor affinities. Herein, we report a facile strategy for fabricating mesoporous 3D few-layered (<4 layers) MoS2 coated TiO2 nanosheet core-shell nanocomposites (denoted as 3D FL-MoS2@TiO2) by a novel two-step method using a smooth TiO2 nanosheet as a template and glucose as a binder. The core-shell structure has been systematically examined and corroborated by transmission electron microscopy, scanning transmission electron microscopy, and X-ray photoelectron spectroscopy analyses. It is found that the resultant 3D FL-MoS2@TiO2 as a lithium-ion battery anode delivers an outstanding high-rate capability with an excellent cycling performance, relating to the unique structure of 3D FL-MoS2@TiO2. The 3D uniform coverage of few-layered (<4 layers) MoS2 onto the TiO2 can remarkably enhance the structure stability and effectively shortens the transfer paths of both lithium ions and electrons, while the strong synergistic effect between MoS2 and TiO2 can significantly facilitate the transport of ions and electrons across the interfaces, especially in the high-rate charge-discharge process. Moreover, the facile fabrication strategy can be easily extended to design other oxide/carbon-sulfide/oxide core-shell materials for extensive applications.Uniform transition metal sulfide deposition on a smooth TiO2 surface to form a coating structure is a well-known challenge, caused mainly due to their poor affinities. Herein, we report a facile strategy for fabricating mesoporous 3D few-layered (<4 layers) MoS2 coated TiO2 nanosheet core-shell nanocomposites (denoted as 3D FL-MoS2@TiO2) by a novel two-step method using a smooth TiO2 nanosheet as a template and glucose as a binder. The core-shell structure has been systematically examined and corroborated by transmission electron microscopy, scanning transmission electron microscopy

Structure analysis for hole-nuclei close to 132Sn by a large-scale shell-model calculation

NASA Astrophysics Data System (ADS)

Wang, Han-Kui; Sun, Yang; Jin, Hua; Kaneko, Kazunari; Tazaki, Shigeru

2013-11-01

The structure of neutron-rich nuclei with a few holes in respect of the doubly magic nucleus 132Sn is investigated by means of large-scale shell-model calculations. For a considerably large model space, including orbitals allowing both neutron and proton core excitations, an effective interaction for the extended pairing-plus-quadrupole model with monopole corrections is tested through detailed comparison between the calculation and experimental data. By using the experimental energy of the core-excited 21/2+ level in 131In as a benchmark, monopole corrections are determined that describe the size of the neutron N=82 shell gap. The level spectra, up to 5 MeV of excitation in 131In, 131Sn, 130In, 130Cd, and 130Sn, are well described and clearly explained by couplings of single-hole orbitals and by core excitations.

Beta Decay Study of the Tz = - 256Zn Nucleus and the Determination of the Half-Lives of a Few fp-shell Nuclei

NASA Astrophysics Data System (ADS)

Rubio, B.; Orrigo, S. E. A.; Kucuk, L.; Montaner-Pizá, A.; Fujita, Y.; Fujita, H.; Blank, B.; Gelletly, W.; Adachi, T.; Agramunt, J.; Algora, A.; Ascher, P.; Bilgier, B.; Cáceres, L.; Cakirli, R. B.; de France, G.; Ganioğlu, E.; Gerbaux, M.; Giovinazzo, J.; Grevy, S.; Kamalou, O.; Kozer, H. C.; Kurtukian-Nieto, T.; Marqués, F. M.; Molina, F.; Oktem, Y.; de Oliveira Santos, F.; Perrot, L.; Popescu, L.; Raabe, R.; Rogers, A. M.; Srivastava, P. C.; Susoy, G.; Suzuki, T.; Tamii, A.; Thomas, J. C.

2014-06-01

This paper concerns the experimental study of the β decay properties of few proton-rich fp-shell nuclei. The nuclei were produced at GANIL in fragmentation reactions, separated with the LISE spectrometer and stopped in an implantation detector surrounded by Ge detectors. The β-delayed gammas, β-delayed protons and the exotic β-delayed gamma-proton emission have been studied. Preliminary results are presented. The decay of the Tz = - 2 nucleus 56Zn has been studied in detail. Information from the β-delayed protons and β-delayed gammas has been used to deduce the decay scheme. The exotic beta-delayed gamma-proton decay has been observed for the first time in the fp-shell. The interpretation of the data was made possible thanks to the detailed knowledge of the mirror Charge Exchange (CE) process and the gamma de-excitation of the states in 56Co, the mirror nucleus of 56Cu.

Isomers and shell evolution in neutron-rich nuclei below the doubly magic nucleus 132Sn

NASA Astrophysics Data System (ADS)

Watanabe, Hiroshi

2018-05-01

The level structures of the very neutron-rich nuclei 128Pd82 and 126Pd80 have been investigated for the first time. A new isomer with a half-life of 5.8(8) μs in 128Pd is proposed to have a spin and parity of 8+ and is associated with a maximally aligned configuration arising from the g9/2Pd proton subshell with seniority υ = 2. The level sequence below the 8+ isomer is similar to that in the N = 82 isotone 130Cd, but the electric quadrupole transition that depopulates the 8+ isomer is more hindered in 128Pd than in 130Cd, as expected in the seniority scheme for a semi-magic, spherical nucleus. For 126Pd, three new isomers with Jπ = (5-), (7-), and (10+) have been identified with half-lives of 0.33(4) μs, 0.44(3) μs, and 23.0(8) ms, respectively. The smaller energy difference between the 10+ and 7- isomers in 126Pd than in the heavier N = 80 isotones can be interpreted as being ascribed to the monopole shift of the h11/2 neutron orbit. The nature of the N = 82 shell closure scrutinized with these characteristic isomers is discussed.

Scattering theory derivation of a 3D acoustic cloaking shell.

PubMed

Cummer, Steven A; Popa, Bogdan-Ioan; Schurig, David; Smith, David R; Pendry, John; Rahm, Marco; Starr, Anthony

2008-01-18

Through acoustic scattering theory we derive the mass density and bulk modulus of a spherical shell that can eliminate scattering from an arbitrary object in the interior of the shell--in other words, a 3D acoustic cloaking shell. Calculations confirm that the pressure and velocity fields are smoothly bent and excluded from the central region as for previously reported electromagnetic cloaking shells. The shell requires an anisotropic mass density with principal axes in the spherical coordinate directions and a radially dependent bulk modulus. The existence of this 3D cloaking shell indicates that such reflectionless solutions may also exist for other wave systems that are not isomorphic with electromagnetics.

Atomistic tight-binding computations of the structural and optical properties of CdTe/CdX (X=S and Se)/ZnS core/shell/shell nanocrystals

NASA Astrophysics Data System (ADS)

Sukkabot, Worasak

2018-05-01

A study of CdTe/CdX (X=S and Se)/ZnS core/shell/shell nanocrystals is carried out using atomistic tight-binding theory and the configuration interaction method to provide information for applications in bioimaging, biolabeling, display devices and near-infrared electronic instruments. The calculations yield the dependences of the internal and external passivated shells on the natural behaviours of CdTe/CdX (X=S and Se)/ZnS core/shell/shell nanocrystals. The reduction of the optical band gaps is observed with increasing numbers of monolayers in the external ZnS shell due to quantum confinement. Interestingly, the optical band gaps of CdTe/CdS/ZnS core/shell/shell nanocrystals are greater than those of CdTe/CdSe/ZnS core/shell/shell nanocrystals. In the presence of an external ZnS-coated shell, electron-hole wave function overlaps, oscillation strengths, ground-state exchange energies and Stokes shift are improved, whereas ground-state coulomb energies and fine-structure splitting are reduced. The oscillation strengths, Stokes shift and fine-structure splitting are reduced with the increase in external ZnS shell thickness. The oscillation strengths, Stokes shift and fine-structure splitting of CdTe/CdS/ZnS core/shell/shell nanocrystals are larger than those of CdTe/CdSe/ZnS core/shell/shell nanocrystals. Reduction of the atomistic electron-hole interactions is observed with increasing external ZnS shell size. The strong electron-hole interactions are more probed in CdTe/CdS/ZnS core/shell/shell nanocrystals than in CdTe/CdSe/ZnS core/shell/shell nanocrystals.

Automatic determination of 3D orientations of fossilized oyster shells from a densely packed Miocene shell bed

NASA Astrophysics Data System (ADS)

Puttonen, Ana; Harzhauser, Mathias; Puttonen, Eetu; Mandic, Oleg; Székely, Balázs; Molnár, Gábor; Pfeifer, Norbert

2018-02-01

Shell beds represent a useful source of information on various physical processes that cause the depositional condition. We present an automated method to calculate the 3D orientations of a large number of elongate and platy objects (fossilized oyster shells) on a sedimentary bedding plane, developed to support the interpretation of possible depositional patterns, imbrications, or impact of local faults. The study focusses on more than 1900 fossil oyster shells exposed in a densely packed Miocene shell bed. 3D data were acquired by terrestrial laser scanning on an area of 459 m2 with a resolution of 1 mm. Bivalve shells were manually defined as 3D-point clouds of a digital surface model and stored in an ArcGIS database. An individual shell coordinate system (ISCS) was virtually embedded into each shell and its orientation was determined relative to the coordinate system of the entire, tectonically tilted shell bed. Orientation is described by the rotation angles roll, pitch, and yaw in a Cartesian coordinate system. This method allows an efficient measurement and analysis of the orientation of thousands of specimens and is a major advantage compared to the traditional 2D approach, which measures only the azimuth (yaw) angles. The resulting data can variously be utilized for taphonomic analyses and the reconstruction of prevailing hydrodynamic regimes and depositional environments. For the first time, the influence of possible post-sedimentary vertical displacements can be quantified with high accuracy. Here, the effect of nearby fault lines—present in the reef—was tested on strongly tilted oyster shells, but it was found out that the fault lines did not have a statistically significant effect on the large tilt angles. Aside from the high reproducibility, a further advantage of the method is its non-destructive nature, which is especially suitable for geoparks and protected sites such as the studied shell bed.

Formation of Hyper Hydrogen isotopes in light p-shell nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jolos, R. V., E-mail: jolos@theor.jinr.ru; Majling, L.; Majlingova, O.

Recent experiment by A1 Collaboration at Mainz, namely identification of {sub Λ}{sup 4}H hyperfragment from primary {sub Λ}{sup 9}Li hypernucleus produced in reaction (e, e′K{sup +}), stirred renewed interest in baryonic decay of hypernuclei. The important role of s{sup −1}s{sub Λ} excitation in p-shell hypernuclei as well as the existence of selection rules connected with [f] (Young diagram) was noted earlier within Translational Invariant Shell Model (TISM). The particular conditions of the present experiment (reaction is not selective and produces highly excited states) dictate extension of the simplest TISM: expansion of the harmonic oscillator basis space and compression of multipletsmore » (to only (λμ) for L and [f] for S, T). Such modified TISM explains abundance production of {sub Λ}{sup 4}H hyperfragment and predicts production of another Hyper Hydrogen {sub Λ}{sup 6}H.« less

D Central Line Extraction of Fossil Oyster Shells

NASA Astrophysics Data System (ADS)

Djuricic, A.; Puttonen, E.; Harzhauser, M.; Mandic, O.; Székely, B.; Pfeifer, N.

2016-06-01

Photogrammetry provides a powerful tool to digitally document protected, inaccessible, and rare fossils. This saves manpower in relation to current documentation practice and makes the fragile specimens more available for paleontological analysis and public education. In this study, high resolution orthophoto (0.5 mm) and digital surface models (1 mm) are used to define fossil boundaries that are then used as an input to automatically extract fossil length information via central lines. In general, central lines are widely used in geosciences as they ease observation, monitoring and evaluation of object dimensions. Here, the 3D central lines are used in a novel paleontological context to study fossilized oyster shells with photogrammetric and LiDAR-obtained 3D point cloud data. 3D central lines of 1121 Crassostrea gryphoides oysters of various shapes and sizes were computed in the study. Central line calculation included: i) Delaunay triangulation between the fossil shell boundary points and formation of the Voronoi diagram; ii) extraction of Voronoi vertices and construction of a connected graph tree from them; iii) reduction of the graph to the longest possible central line via Dijkstra's algorithm; iv) extension of longest central line to the shell boundary and smoothing by an adjustment of cubic spline curve; and v) integration of the central line into the corresponding 3D point cloud. The resulting longest path estimate for the 3D central line is a size parameter that can be applied in oyster shell age determination both in paleontological and biological applications. Our investigation evaluates ability and performance of the central line method to measure shell sizes accurately by comparing automatically extracted central lines with manually collected reference data used in paleontological analysis. Our results show that the automatically obtained central line length overestimated the manually collected reference by 1.5% in the test set, which is deemed

NMDA and dopamine D1 receptors within NAc-shell regulate IEG proteins expression in reward circuit during cocaine memory reconsolidation.

PubMed

Li, Y; Ge, S; Li, N; Chen, L; Zhang, S; Wang, J; Wu, H; Wang, X; Wang, X

2016-02-19

Reactivation of consolidated memory initiates a memory reconsolidation process, during which the reactivated memory is susceptible to strengthening, weakening or updating. Therefore, effective interference with the memory reconsolidation process is expected to be an important treatment for drug addiction. The nucleus accumbens (NAc) has been well recognized as a pathway component that can prevent drug relapse, although the mechanism underlying this function is poorly understood. We aimed to clarify the regulatory role of the NAc in the cocaine memory reconsolidation process, by examining the effect of applying different pharmacological interventions to the NAc on Zif 268 and Fos B expression in the entire reward circuit after cocaine memory reactivation. Through the cocaine-induced conditioned place preference (CPP) model, immunohistochemical and immunofluorescence staining for Zif 268 and Fos B were used to explore the functional activated brain nuclei after cocaine memory reactivation. Our results showed that the expression of Zif 268 and Fos B was commonly increased in the medial prefrontal cortex (mPFC), the infralimbic cortex (IL), the NAc-core, the NAc-shell, the hippocampus (CA1, CA2, and CA3 subregions), the amygdala, the ventral tegmental area (VTA), and the supramammillary nucleus (SuM) following memory reconsolidation, and Zif 268/Fos B co-expression was commonly observed (for Zif 268: 51-68%; for Fos B: 52-66%). Further, bilateral NAc-shell infusion of MK 801 and SCH 23390, but not raclopride or propranolol, prior to addictive memory reconsolidation, decreased Zif 268 and Fos B expression in the entire reward circuit, except for the amygdala, and effectively disturbed subsequent CPP-related behavior. In summary, N-methyl-d-aspartate (NMDA) and dopamine D1 receptors, but not dopamine D2 or β adrenergic receptors, within the NAc-shell, may regulate Zif 268 and Fos B expression in most brain nuclei of the reward circuit after cocaine memory reactivation

Quasifree (p ,p N ) scattering of light neutron-rich nuclei near N =14

NASA Astrophysics Data System (ADS)

Díaz Fernández, P.; Alvarez-Pol, H.; Crespo, R.; Cravo, E.; Atar, L.; Deltuva, A.; Aumann, T.; Avdeichikov, V.; Beceiro-Novo, S.; Bemmerer, D.; Benlliure, J.; Bertulani, C. A.; Boillos, J. M.; Boretzky, K.; Borge, M. J. G.; Caamaño, M.; Cabanelas, P.; Caesar, C.; Casarejos, E.; Catford, W.; Cederkäll, J.; Chartier, M.; Chulkov, L. V.; Cortina-Gil, D.; Datta Pramanik, U.; Dillmann, I.; Elekes, Z.; Enders, J.; Ershova, O.; Estradé, A.; Farinon, F.; Fernández-Domínguez, B.; Fraile, L. M.; Freer, M.; Galaviz, D.; Geissel, H.; Gernhäuser, R.; Golubev, P.; Göbel, K.; Hagdahl, J.; Heftrich, T.; Heil, M.; Heine, M.; Heinz, A.; Henriques, A.; Holl, M.; Hufnagel, A.; Ignatov, A.; Johansson, H. T.; Jonson, B.; Jurčiukonis, D.; Kalantar-Nayestanaki, N.; Kanungo, R.; Kelic-Heil, A.; Knyazev, A.; Kröll, T.; Kurz, N.; Labiche, M.; Langer, C.; Le Bleis, T.; Lemmon, R.; Lindberg, S.; Machado, J.; Marganiec, J.; Moro, A. M.; Movsesyan, A.; Nacher, E.; Najafi, A.; Nikolskii, E.; Nilsson, T.; Nociforo, C.; Panin, V.; Paschalis, S.; Perea, A.; Petri, M.; Pietras, B.; Pietri, S.; Plag, R.; Reifarth, R.; Ribeiro, G.; Rigollet, C.; Rossi, D.; Röder, M.; Savran, D.; Scheit, H.; Simon, H.; Sorlin, O.; Syndikus, I.; Taylor, J. T.; Tengblad, O.; Thies, R.; Togano, Y.; Vandebrouck, M.; Velho, P.; Volkov, V.; Wagner, A.; Wamers, F.; Weick, H.; Wheldon, C.; Wilson, G.; Winfield, J. S.; Woods, P.; Yakorev, D.; Zhukov, M.; Zilges, A.; Zuber, K.; R³B Collaboration

2018-02-01

Background: For many years, quasifree scattering reactions in direct kinematics have been extensively used to study the structure of stable nuclei, demonstrating the potential of this approach. The R 3B collaboration has performed a pilot experiment to study quasifree scattering reactions in inverse kinematics for a stable 12C beam. The results from that experiment constitute the first quasifree scattering results in inverse and complete kinematics. This technique has lately been extended to exotic beams to investigate the evolution of shell structure, which has attracted much interest due to changes in shell structure if the number of protons or neutrons is varied. Purpose: In this work we investigate for the first time the quasifree scattering reactions (p ,p n ) and (p ,2 p ) simultaneously for the same projectile in inverse and complete kinematics for radioactive beams with the aim to study the evolution of single-particle properties from N =14 to N =15 . Method: The structure of the projectiles 23O, 22O, and 21N has been studied simultaneously via (p ,p n ) and (p ,2 p ) quasifree knockout reactions in complete inverse kinematics, allowing the investigation of proton and neutron structure at the same time. The experimental data were collected at the R3B -LAND setup at GSI at beam energies of around 400 MeV/u. Two key observables have been studied to shed light on the structure of those nuclei: the inclusive cross sections and the corresponding momentum distributions. Conclusions: The knockout reactions (p ,p n ) and (p ,2 p ) with radioactive beams in inverse kinematics have provided important and complementary information for the study of shell evolution and structure. For the (p ,p n ) channels, indications of a change in the structure of these nuclei moving from N =14 to N =15 have been observed, i.e., from the 0 d5 /2 shell to the 1 s1 /2 . This supports previous observations of a subshell closure at N =14 for neutron-rich oxygen isotopes and its weakening

Fluorescence properties of alloyed ZnSeS quantum dots overcoated with ZnTe and ZnTe/ZnS shells

NASA Astrophysics Data System (ADS)

Adegoke, Oluwasesan; Mashazi, Philani; Nyokong, Tebello; Forbes, Patricia B. C.

2016-04-01

Fluorescent alloyed ternary ZnSeS quantum dots (QDs) have been synthesized via the pyrolysis of organometallic precursors. The effects of passivation of ZnTe and ZnTe/ZnS shells on the optical properties of the ternary alloyed ZnSeS core have been studied. A ligand exchange reaction using L-cysteine as a capping ligand was used to obtain water-soluble nanocrystals. The nanocrystals were each characterized by UV/vis absorption and fluorescence spectroscopy, transmission electron microscopy, X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS). The photoluminescence (PL) quantum yield (QY) of alloyed ZnSeS QDs was 14% and this value increased to 27% when ZnTe was overcoated around the surface but further coating with a ZnS shell decreased the PL QY slightly to 24%. This implies that ZnTe shell suppressed non-radiative recombination exciton states in the alloyed core while further layering with a ZnS shell offered no further improvement in suppressing the defect states. XPS analysis confirmed the presence of the first shell layering but showed a weakened intensity signal of S (2p) and Se (3d) for the ZnSeS/ZnTe/ZnS QDs. Our work demonstrates for the first time that shell passivation of alloyed Zn-based QDs can offer improved optical properties. We hope the optical information presented in this work will be useful in the selection of alloyed Zn-based QDs appropriate for the intended application.

Proxy-SU(3) symmetry in heavy deformed nuclei

NASA Astrophysics Data System (ADS)

Bonatsos, Dennis; Assimakis, I. E.; Minkov, N.; Martinou, Andriana; Cakirli, R. B.; Casten, R. F.; Blaum, K.

2017-06-01

Background: Microscopic calculations of heavy nuclei face considerable difficulties due to the sizes of the matrices that need to be solved. Various approximation schemes have been invoked, for example by truncating the spaces, imposing seniority limits, or appealing to various symmetry schemes such as pseudo-SU(3). This paper proposes a new symmetry scheme also based on SU(3). This proxy-SU(3) can be applied to well-deformed nuclei, is simple to use, and can yield analytic predictions. Purpose: To present the new scheme and its microscopic motivation, and to test it using a Nilsson model calculation with the original shell model orbits and with the new proxy set. Method: We invoke an approximate, analytic, treatment of the Nilsson model, that allows the above vetting and yet is also transparent in understanding the approximations involved in the new proxy-SU(3). Results: It is found that the new scheme yields a Nilsson diagram for well-deformed nuclei that is very close to the original Nilsson diagram. The specific levels of approximation in the new scheme are also shown, for each major shell. Conclusions: The new proxy-SU(3) scheme is a good approximation to the full set of orbits in a major shell. Being able to replace a complex shell model calculation with a symmetry-based description now opens up the possibility to predict many properties of nuclei analytically and often in a parameter-free way. The new scheme works best for heavier nuclei, precisely where full microscopic calculations are most challenged. Some cases in which the new scheme can be used, often analytically, to make specific predictions, are shown in a subsequent paper.

Evaluation of cluster expansions and correlated one-body properties of nuclei

NASA Astrophysics Data System (ADS)

Moustakidis, Ch. C.; Massen, S. E.; Panos, C. P.; Grypeos, M. E.; Antonov, A. N.

2001-07-01

Three different cluster expansions for the evaluation of correlated one-body properties of s-p and s-d shell nuclei are compared. Harmonic oscillator wave functions and Jastrow-type correlations are used, while analytical expressions are obtained for the charge form factor, density distribution, and momentum distribution by truncating the expansions and using a standard Jastrow correlation function f. The harmonic oscillator parameter b and the correlation parameter β have been determined by a least-squares fit to the experimental charge form factors in each case. The information entropy of nuclei in position space (Sr) and momentum space (Sk) according to the three methods are also calculated. It is found that the larger the entropy sum, S=Sr+Sk (the net information content of the system), the smaller the values of χ2. This indicates that maximal S is a criterion of the quality of a given nuclear model, according to the maximum entropy principle. Only two exceptions to this rule, out of many cases examined, were found. Finally an analytic expression for the so-called ``healing'' or ``wound'' integrals is derived with the function f considered, for any state of the relative two-nucleon motion, and their values in certain cases are computed and compared.

Deformed shell model results for neutrinoless positron double beta decay of nuclei in the A = 60-90 region

NASA Astrophysics Data System (ADS)

Sahu, R.; Srivastava, P. C.; Kota, V. K. B.

2013-09-01

Nuclear transition matrix elements (NTME) for neutrinoless positron double beta decay (0νβ+β+ and 0νβ+EC) of 64Zn, 74Se, 78Kr and 84Sr nuclei, which are in the A = 60-90 region, are calculated within the framework of the deformed shell model (DSM) based on Hartree-Fock states. For 64Zn, GXPF1A interaction in 1f7/2, 2p3/2, 1f5/2 and 2p1/2 space with 40Ca as the core is employed. Similarly for 74Se, 78Kr and 84Sr nuclei, 56Ni is taken as the inert core employing a modified Kuo interaction in 2p3/2, 1f5/2, 2p1/2 and 1g9/2 space. After ensuring that the DSM gives a good description of the spectroscopic properties of low-lying levels in the four nuclei considered, the NTME are calculated. The half-lives deduced with these NTME, assuming the neutrino mass is 1 eV, are smallest for 78Kr with the half-life for β+EC decay being ˜1027 yr. For all others, the half-lives are in the range of ˜1028-1029 yr.

3D segmentations of neuronal nuclei from confocal microscope image stacks

PubMed Central

LaTorre, Antonio; Alonso-Nanclares, Lidia; Muelas, Santiago; Peña, José-María; DeFelipe, Javier

2013-01-01

In this paper, we present an algorithm to create 3D segmentations of neuronal cells from stacks of previously segmented 2D images. The idea behind this proposal is to provide a general method to reconstruct 3D structures from 2D stacks, regardless of how these 2D stacks have been obtained. The algorithm not only reuses the information obtained in the 2D segmentation, but also attempts to correct some typical mistakes made by the 2D segmentation algorithms (for example, under segmentation of tightly-coupled clusters of cells). We have tested our algorithm in a real scenario—the segmentation of the neuronal nuclei in different layers of the rat cerebral cortex. Several representative images from different layers of the cerebral cortex have been considered and several 2D segmentation algorithms have been compared. Furthermore, the algorithm has also been compared with the traditional 3D Watershed algorithm and the results obtained here show better performance in terms of correctly identified neuronal nuclei. PMID:24409123

3D segmentations of neuronal nuclei from confocal microscope image stacks.

PubMed

Latorre, Antonio; Alonso-Nanclares, Lidia; Muelas, Santiago; Peña, José-María; Defelipe, Javier

2013-01-01

In this paper, we present an algorithm to create 3D segmentations of neuronal cells from stacks of previously segmented 2D images. The idea behind this proposal is to provide a general method to reconstruct 3D structures from 2D stacks, regardless of how these 2D stacks have been obtained. The algorithm not only reuses the information obtained in the 2D segmentation, but also attempts to correct some typical mistakes made by the 2D segmentation algorithms (for example, under segmentation of tightly-coupled clusters of cells). We have tested our algorithm in a real scenario-the segmentation of the neuronal nuclei in different layers of the rat cerebral cortex. Several representative images from different layers of the cerebral cortex have been considered and several 2D segmentation algorithms have been compared. Furthermore, the algorithm has also been compared with the traditional 3D Watershed algorithm and the results obtained here show better performance in terms of correctly identified neuronal nuclei.

Deriving the nuclear shell model from first principles

NASA Astrophysics Data System (ADS)

Barrett, Bruce R.; Dikmen, Erdal; Vary, James P.; Maris, Pieter; Shirokov, Andrey M.; Lisetskiy, Alexander F.

2014-09-01

The results of an 18-nucleon No Core Shell Model calculation, performed in a large basis space using a bare, soft NN interaction, can be projected into the 0 ℏω space, i.e., the sd -shell. Because the 16 nucleons in the 16O core are frozen in the 0 ℏω space, all the correlations of the 18-nucleon system are captured by the two valence, sd -shell nucleons. By the projection, we obtain microscopically the sd -shell 2-body effective interactions, the core energy and the sd -shell s.p. energies. Thus, the input for standard shell-model calculations can be determined microscopically by this approach. If the same procedure is then applied to 19-nucleon systems, the sd -shell 3-body effective interactions can also be obtained, indicating the importance of these 3-body effective interactions relative to the 2-body effective interactions. Applications to A = 19 and heavier nuclei with different intrinsic NN interactions will be presented and discussed. The results of an 18-nucleon No Core Shell Model calculation, performed in a large basis space using a bare, soft NN interaction, can be projected into the 0 ℏω space, i.e., the sd -shell. Because the 16 nucleons in the 16O core are frozen in the 0 ℏω space, all the correlations of the 18-nucleon system are captured by the two valence, sd -shell nucleons. By the projection, we obtain microscopically the sd -shell 2-body effective interactions, the core energy and the sd -shell s.p. energies. Thus, the input for standard shell-model calculations can be determined microscopically by this approach. If the same procedure is then applied to 19-nucleon systems, the sd -shell 3-body effective interactions can also be obtained, indicating the importance of these 3-body effective interactions relative to the 2-body effective interactions. Applications to A = 19 and heavier nuclei with different intrinsic NN interactions will be presented and discussed. Supported by the US NSF under Grant No. 0854912, the US DOE under

An Infrared Search for HDO in Comet D/2012 S1 (ISON) and Implications for iSHELL

NASA Technical Reports Server (NTRS)

Gibb, Erika L.; Bonev, Boncho P.; DiSanti, Michael A.; Villanueva, Geronimo L.; Paganini, Lucas; Mumma, Michael J.

2016-01-01

We performed a sensitive search for HDO in comet D/2012 S1 (ISON) on 2013 November 16, 17, and 22 using CSHELL and the NASA Infrared Telescope Facility. We constrained the HDO/H2O ratio to less than 2.0 VSMOW (the terrestrial ocean value) at the 3 sigma uncertainty level from two independent measurements corresponding to different H2O outgassing rates. This represents the best constrained HDO/H2O ratio for a comet using a small (3 m) telescope and illustrates that when CSHELL is replaced with iSHELL, 3 m class telescopes are still strong contenders for detecting minor volatile species in moderately bright comets.

CdS/ZnS core-shell nanocrystal photosensitizers for visible to UV upconversion.

PubMed

Gray, Victor; Xia, Pan; Huang, Zhiyuan; Moses, Emily; Fast, Alexander; Fishman, Dmitry A; Vullev, Valentine I; Abrahamsson, Maria; Moth-Poulsen, Kasper; Lee Tang, Ming

2017-08-01

Herein we report the first example of nanocrystal (NC) sensitized triplet-triplet annihilation based photon upconversion from the visible to ultraviolet (vis-to-UV). Many photocatalyzed reactions, such as water splitting, require UV photons in order to function efficiently. Upconversion is one possible means of extending the usable range of photons into the visible. Vis-to-UV upconversion is achieved with CdS/ZnS core-shell NCs as the sensitizer and 2,5-diphenyloxazole (PPO) as annihilator and emitter. The ZnS shell was crucial in order to achieve any appreciable upconversion. From time resolved photoluminescence and transient absorption measurements we conclude that the ZnS shell affects the NC and triplet energy transfer (TET) from NC to PPO in two distinct ways. Upon ZnS growth the surface traps are passivated thus increasing the TET. The shell, however, also acts as a tunneling barrier for TET, reducing the efficiency. This leads to an optimal shell thickness where the upconversion quantum yield ( Φ ' UC ) is maximized. Here the maximum Φ ' UC was determined to be 5.2 ± 0.5% for 4 monolayers of ZnS shell on CdS NCs.

Statistical theory of light nucleus reactions with 1p-shell light nuclei

NASA Astrophysics Data System (ADS)

Xiaojun, Sun; Jingshang, Zhang

2017-09-01

The 1p-shell light elements (Li, Be, B, C, N, and O) had long been selected as the most important materials for improving neutron economy in thermal and fast fission reactors and in the design of accelerator-driven spallation neutron sources. A statistical theory of light nucleus reactions (STLN) is proposed to describe the double-differential cross sections for both neutron and light charged particle induced nuclear reactions with 1p-shell light nuclei. The dynamics of STLN is described by the unified Hauser-Feshbach and exciton model, in which the angular momentum and parity conservations are strictly considered in equilibrium and pre-equilibrium processes. The Coulomb barriers of the incoming and outgoing charged particles, which significantly influence the open channels of the reaction, can be reasonably considered in incident channel and different outgoing channels. In kinematics, the recoiling effects in various emission processes are strictly taken into account. The analytical energy and angular spectra of the reaction products in sequential and simultaneous emission processes are obtained in terms of the new integral formula proposed in our recent paper. Taking 12C(n, xn), 9Be(n, xn), 16O(n, xn), and 9Be(p,xn) reactions as examples, we had calculated the double-differential cross sections of outgoing neutrons and compared with the experimental data. In addition, we had also calculated the partition and total kerma coefficients for 12C(n, xn) and 16O(n, xn) reactions, respectively. The existing experimental data can be remarkably well reproduced by STLN, which had been used to set up file-6 in CENDL database.

Nilsson diagrams for light neutron-rich nuclei with weakly-bound neutrons

NASA Astrophysics Data System (ADS)

Hamamoto, Ikuko

2007-11-01

Using Woods-Saxon potentials and the eigenphase formalism for one-particle resonances, one-particle bound and resonant levels for neutrons as a function of quadrupole deformation are presented, which are supposed to be useful for the interpretation of spectroscopic properties of some light neutron-rich nuclei with weakly bound neutrons. Compared with Nilsson diagrams in textbooks that are constructed using modified oscillator potentials, we point out a systematic change of the shell structure in connection with both weakly bound and resonant one-particle levels related to small orbital angular momenta ℓ. Then, it is seen that weakly bound neutrons in nuclei such as C15-19 and Mg33-37 may prefer being deformed as a result of the Jahn-Teller effect, due to the near degeneracy of the 1d5/2-2s1/2 levels and the 1f7/2-2p3/2 levels in the spherical potential, respectively. Furthermore, the absence of some one-particle resonant levels compared with the Nilsson diagrams in textbooks is illustrated.

Systematic study of fission barriers of excited superheavy nuclei

NASA Astrophysics Data System (ADS)

Sheikh, J. A.; Nazarewicz, W.; Pei, J. C.

2009-07-01

A systematic study of fission-barrier dependence on excitation energy has been performed using the self-consistent finite-temperature Hartree-Fock + BCS (FT-HF + BCS) formalism with the SkM* Skyrme energy density functional. The calculations have been carried out for even-even superheavy nuclei with Z ranging between 110 and 124. For an accurate description of fission pathways, the effects of triaxial and reflection-asymmetric degrees of freedom have been fully incorporated. Our survey demonstrates that the dependence of isentropic fission barriers on excitation energy changes rapidly with particle number, pointing to the importance of shell effects even at large excitation energies characteristic of compound nuclei. The fastest decrease of fission barriers with excitation energy is predicted for deformed nuclei around N=164 and spherical nuclei around N=184 that are strongly stabilized by ground-state shell effects. For the nuclei Pu240 and Fm256, which exhibit asymmetric spontaneous fission, our calculations predict a transition to symmetric fission at high excitation energies owing to the thermal quenching of static reflection asymmetric deformations.

Systematics of g factors of 2{sub 1}{sup +} states in even-even nuclei from Gd to Pt: A microscopic description by the projected shell model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bian, Bao-An; Institute of Low Energy Nuclear Physics, Beijing Normal University, Beijing 100875; Di, Yao-Min

2007-01-15

The systematics of g factor of the first excited 2{sup +} state vs neutron number N is studied by the projected shell model. The study covers the even-even nuclei of all isotopic chains from Gd to Pt. g factors are calculated by using the many-body wave functions that well reproduce the energy levels and B(E2)s of the ground-state bands. For Gd to W isotopes the characteristic feature of the g factor data along an isotopic chain is described by the present model. Deficiency of the model in the g factor description for the heavier Os and Pt isotopes is discussed.

The Design of 3D-Printed Lattice-Reinforced Thickness-Varying Shell Molds for Castings

PubMed Central

Shangguan, Haolong; Kang, Jinwu; Yi, Jihao; Zhang, Xiaochuan; Wang, Xiang; Wang, Haibin; Huang, Tao

2018-01-01

3D printing technologies have been used gradually for the fabrication of sand molds and cores for castings, even though these molds and cores are dense structures. In this paper, a generation method for lattice-reinforced thickness-varying shell molds is proposed and presented. The first step is the discretization of the STL (Stereo Lithography) model of a casting into finite difference meshes. After this, a shell is formed by surrounding the casting with varying thickness, which is roughly proportional to the surface temperature distribution of the casting that is acquired by virtually cooling it in the environment. A regular lattice is subsequently constructed to support the shell. The outside surface of the shell and lattice in the cubic mesh format is then converted to STL format to serve as the external surface of the new shell mold. The internal surface of the new mold is the casting’s surface with the normals of all of the triangles in STL format reversed. Experimental verification was performed on an Al alloy wheel hub casting. Its lattice-reinforced thickness-varying shell mold was generated by the proposed method and fabricated by the binder jetting 3D printing. The poured wheel hub casting was sound and of good surface smoothness. The cooling rate of the wheel hub casting was greatly increased due to the shell mold structure. This lattice-reinforced thickness-varying shell mold generation method is of great significance for mold design for castings to achieve cooling control. PMID:29601543

Tunable luminescent emission characterization of type-I and type-II systems in CdS-ZnSe core-shell nanoparticles: Raman and photoluminescence study.

PubMed

Ca, Nguyen Xuan; Lien, V T K; Nghia, N X; Chi, T T K; Phan, The-Long

2015-11-06

We used wet chemical methods to synthesize core-shell nanocrystalline samples CdS(d)/ZnSe N , where d = 3-6 nm and N = 1-5 are the size of CdS cores and the number of monolayers grown on the cores, respectively. By annealing typical CdS(d)/ZnSe N samples (with d = 3 and 6 nm and N = 2) at 300 °C for various times t an = 10-600 min, we created an intermediate layer composed of Zn1-x Cd x Se and Cd1-x Zn x S alloys with various thicknesses. The formation of core-shell structures and intermediate layers was monitored by Raman scattering and UV-vis absorption spectrometers. Careful photoluminescence studies revealed that the as-prepared CdS(d)/ZnSe N samples with d = 5 nm and N = 2-4, and the annealed samples CdS(3 nm)/ZnSe2 with t an ≤ 60 min and CdS(6 nm)/ZnSe2 with t an ≤ 180 min, show the emission characteristics of type-II systems. Meanwhile, the other samples show the emission characteristics of type-I systems. These results prove that the partial separation of photoexcited carriers between the core and shell is dependent strongly on the engineered core-shell nanostructures, meaning the sizes of the core, shell, and intermediate layers. With the tunable luminescence properties, CdS-ZnSe-based core-shell materials are considered as promising candidates for multiple-exciton generation and single-photon sources.

Preparation of yolk-shell MoS2 nanospheres covered with carbon shell for excellent lithium-ion battery anodes

NASA Astrophysics Data System (ADS)

Guo, Bangjun; Feng, Yu; Chen, Xiaofan; Li, Bo; Yu, Ke

2018-03-01

Molybdenum disulfide is regarded as one of the most promising electrode materials for high performance lithium-ion batteries. Designing firm basal structure is a key point to fully utilize the high capacity of layered MoS2 nanomaterials. Here, yolk-shell structured MoS2 nanospheres is firstly designed and fabricated to meet this needs. This unique yolk-shell nanospheres are transformed from solid nanospheres by a simply weak alkaline etching method. Then, the yolk-shell MoS2/C is synthesized by a facile process to protect the outside MoS2 shell and promote the conductivity. Taking advantages of high capacity and well-defined cavity space, allowing the core MoS2 to expand freely without breaking the outer shells, yolk-shell MoS2/C nanospheres delivers long cycle life (94% of capacity retained after 200 cycles) and high rate behaviour (830 mA h g-1 at 5 A g-1). This design of yolk-shell structure may set up a new strategy for preparing next generation anode materials for LIBs.

Ionic bonding of lanthanides, as influenced by d- and f-atomic orbitals, by core-shells and by relativity.

PubMed

Ji, Wen-Xin; Xu, Wei; Schwarz, W H Eugen; Wang, Shu-Guang

2015-03-15

Lanthanide trihalide molecules LnX3 (X = F, Cl, Br, I) were quantum chemically investigated, in particular detail for Ln = Lu (lutetium). We applied density functional theory (DFT) at the nonrelativistic and scalar and SO-coupled relativistic levels, and also the ab initio coupled cluster approach. The chemically active electron shells of the lanthanide atoms comprise the 5d and 6s (and 6p) valence atomic orbitals (AO) and also the filled inner 4f semivalence and outer 5p semicore shells. Four different frozen-core approximations for Lu were compared: the (1s(2) -4d(10) ) [Pd] medium core, the [Pd+5s(2) 5p(6) = Xe] and [Pd+4f(14) ] large cores, and the [Pd+4f(14) +5s(2) 5p(6) ] very large core. The errors of LuX bonding are more serious on freezing the 5p(6) shell than the 4f(14) shell, more serious upon core-freezing than on the effective-core-potential approximation. The LnX distances correlate linearly with the AO radii of the ionic outer shells, Ln(3+) -5p(6) and X(-) -np(6) , characteristic for dominantly ionic Ln(3+) -X(-) binding. The heavier halogen atoms also bind covalently with the Ln-5d shell. Scalar relativistic effects contract and destabilize the LuX bonds, spin orbit coupling hardly affects the geometries but the bond energies, owing to SO effects in the free atoms. The relativistic changes of bond energy BE, bond length Re , bond force k, and bond stretching frequency vs do not follow the simple rules of Badger and Gordy (Re ∼BE∼k∼vs ). The so-called degeneracy-driven covalence, meaning strong mixing of accidentally near-degenerate, nearly nonoverlapping AOs without BE contribution is critically discussed. © 2015 Wiley Periodicals, Inc.

AN INFRARED SEARCH FOR HDO IN COMET D/2012 S1 (ISON) AND IMPLICATIONS FOR iSHELL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gibb, Erika L.; Bonev, Boncho P.; Villanueva, Geronimo L.

2016-01-10

We performed a sensitive search for HDO in comet D/2012 S1 (ISON) on 2013 November 16, 17, and 22 using CSHELL and the NASA Infrared Telescope Facility. We constrained the HDO/H{sub 2}O ratio to <2.0 VSMOW (the terrestrial ocean value) at the 3σ uncertainty level from two independent measurements corresponding to different H{sub 2}O outgassing rates. This represents the best constrained HDO/H{sub 2}O ratio for a comet using a small (3 m) telescope and illustrates that when CSHELL is replaced with iSHELL, 3 m class telescopes are still strong contenders for detecting minor volatile species in moderately bright comets.

Role of shell corrections in the phenomenon of cluster radioactivity

NASA Astrophysics Data System (ADS)

Kaur, Mandeep; Singh, Bir Bikram; Sharma, Manoj K.

2018-05-01

The detailed investigation has been carried out to explore the role of shell corrections in the decay of various radioactive parent nuclei in trans-lead region, specifically, which lead to doubly magic 208Pb daughter nucleus through emission of clusters such as 14C, 18,20O, 22,24,26Ne, 28,30 Mg and 34S i. The fragmentation potential comprises of binding energies (BE), Coulomb potential (Vc) and nuclear or proximity potential (VP) of the decaying fragments (or clusters). It is relevant to mention here that the contributions of VLDM (T=0) and δU (T=0) in the BE have been analysed within the Strutinsky renormanlization procedure. In the framework of quantum mechanical fragmentation theory (QMFT), we have investigated the above mentioned cluster decays with and without inclusion of shell corrections in the fragmentation potential for spherical as well as non-compact oriented nuclei. We find that the experimentally observed clusters 14C, 18,20O, 22,24,26 Ne, 28,30 Mg and 34Si having doubly magic 208 Pb daughter nucleus are not strongly minimized, they do so only after the inclusion of shell corrections in the fragmentation potential. The nuclear structure information carried by the shell corrections have been explored via these calculations, within the collective clusterisation process of QMFT, in the study of ground state decay of radioactive nuclei. The role of different parts of fragmentation potentials such as VLDM, δU, Vc and Vp is dually analysed for better understanding of radioactive cluster decay.

Magnetic moments of excited states in nuclei far from stability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wolf, A.; Berant, Z.; Gill, R.L.

1985-01-01

Magnetic moments of excited states in nuclei far from stability have been measured by gamma-gamma angular correlation at the output of the fission product separators TRISTAN and JOSEF. The results obtained until now will be reviewed. They provide important nuclear structure information about nuclei around closed shells, and transitional nuclei in the A = 100 and 150 regions. 22 refs., 3 figs., 3 tabs.

Quartetting in even-even and odd-odd N=Z nuclei

NASA Astrophysics Data System (ADS)

Sambataro, M.; Sandulescu, N.

2018-02-01

We report on a microscopic description of even-even N = Z nuclei in a formalism of quartets. Quartets are four-body correlated structures characterized by isospin T and angular momentum J. We show that the ground state correlations induced by a realistic shell model interaction can be well accounted for in terms of a restricted set of T = 0 low-J quartets, the J = 0 one playing by far a leading role among them. A conceptually similar description of odd-odd self-conjugate nuclei is given in terms of two distinct families of building blocks, one formed by the same T = 0 quartets employed for the even-even systems and the other by collective pairs with either T = 0 or T = 1. Some applications of this formalism are discussed for nuclei in the sd shell.

Systematic study of α decay of nuclei around the Z =82 , N =126 shell closures within the cluster-formation model and proximity potential 1977 formalism

NASA Astrophysics Data System (ADS)

Deng, Jun-Gang; Zhao, Jie-Cheng; Chu, Peng-Cheng; Li, Xiao-Hua

2018-04-01

In the present work, we systematically study the α decay preformation factors Pα within the cluster-formation model and α decay half-lives by the proximity potential 1977 formalism for nuclei around Z =82 ,N =126 closed shells. The calculations show that the realistic Pα is linearly dependent on the product of valance protons (holes) and valance neutrons (holes) NpNn . It is consistent with our previous works [Sun et al., Phys. Rev. C 94, 024338 (2016), 10.1103/PhysRevC.94.024338; Deng et al., Phys. Rev. C 96, 024318 (2017), 10.1103/PhysRevC.96.024318], in which Pα are model dependent and extracted from the ratios of calculated α half-lives to experimental data. Combining with our previous works, we confirm that the valance proton-neutron interaction plays a key role in the α preformation for nuclei around Z =82 ,N =126 shell closures whether the Pα is model dependent or microcosmic. In addition, our calculated α decay half-lives by using the proximity potential 1977 formalism taking Pα evaluated by the cluster-formation model can well reproduce the experimental data and significantly reduce the errors.

Physical insight into light scattering by photoreceptor cell nuclei.

PubMed

Kreysing, Moritz; Boyde, Lars; Guck, Jochen; Chalut, Kevin J

2010-08-01

A recent study showed that the rod photoreceptor cell nuclei in the retina of nocturnal and diurnal mammals differ considerably in architecture: the location of euchromatin and heterochromatin in the nucleus is interchanged. This inversion has significant implications for the refractive index distribution and the light scattering properties of the nucleus. Here, we extend previous two-dimensional analysis to three dimensions (3D) by using both a numerical finite-difference time-domain and an analytic Mie theory approach. We find that the specific arrangement of the chromatin phases in the nuclear core-shell models employed have little impact on the far-field scattering cross section. However, scattering in the near field, which is the relevant regime inside the retina, shows a significant difference between the two architectures. The "inverted" photoreceptor cell nuclei of nocturnal mammals act as collection lenses, with the lensing effect being much more pronounced in 3D than in two dimensions. This lensing helps to deliver light efficiently to the light-sensing outer segments of the rod photoreceptor cells and thereby improve night vision.

Fabrication and investigation of effect of core size in heterostructure PbS/CdS core/shell nanoparticles

NASA Astrophysics Data System (ADS)

Das, D.; Hussain, A. M. P.

2018-04-01

PbS/CdS core/shell (CS) nanoparticles (NPs) were fabricated with three different concentrations of PbS core and CdS shell. Formation of core/shell heterostructure was confirmed from X-ray diffraction studies. The diffraction patterns exhibited formation of cubic phase and polycrystalline core/shell nanostructure. The crystalline sizes calculated from Williamson-Hall plot exhibited increase with molar concentration of precursors with decrease in strain. High resolution electron microscopy studies also confirm the formation of core/shell structure with particle size around 10 nm. A large blue-shift for PbS core compared to its bulk and small red-shift for the PbS/CdS core/shell as compared to the core is being observed in absorption spectra.

Probable alpha and 14C cluster emission from hyper Ac nuclei

NASA Astrophysics Data System (ADS)

Santhosh, K. P.

2013-10-01

A systematic study on the probability for the emission of 4He and 14C cluster from hyper {Λ/207-234}Ac and non-strange normal 207-234Ac nuclei are performed for the first time using our fission model, the Coulomb and proximity potential model (CPPM). The predicted half lives show that hyper {Λ/207-234}Ac nuclei are unstable against 4He emission and 14C emission from hyper {Λ/217-228}Ac are favorable for measurement. Our study also show that hyper {Λ/207-234}Ac are stable against hyper {Λ/4}He and {Λ/14}C emission. The role of neutron shell closure ( N = 126) in hyper {Λ/214}Fr daughter and role of proton/neutron shell closure ( Z ≈ 82, N = 126) in hyper {Λ/210}Bi daughter are also revealed. As hyper-nuclei decays to normal nuclei by mesonic/non-mesonic decay and since most of the predicted half lives for 4He and 14C emission from normal Ac nuclei are favourable for measurement, we presume that alpha and 14C cluster emission from hyper Ac nuclei can be detected in laboratory in a cascade (two-step) process.

New Equations of State Based on the Liquid Drop Model of Heavy Nuclei and Quantum Approach to Light Nuclei for Core-collapse Supernova Simulations

NASA Astrophysics Data System (ADS)

Furusawa, Shun; Sumiyoshi, Kohsuke; Yamada, Shoichi; Suzuki, Hideyuki

2013-08-01

We construct new equations of state for baryons at subnuclear densities for the use in core-collapse simulations of massive stars. The abundance of various nuclei is obtained together with thermodynamic quantities. A model free energy is constructed, based on the relativistic mean field theory for nucleons and the mass formula for nuclei with the proton number up to ~1000. The formulation is an extension of the previous model, in which we adopted the liquid drop model to all nuclei under the nuclear statistical equilibrium. We reformulate the new liquid drop model so that the temperature dependences of bulk energies could be taken into account. Furthermore, we extend the region in the nuclear chart, in which shell effects are included, by using theoretical mass data in addition to experimental ones. We also adopt a quantum-theoretical mass evaluation of light nuclei, which incorporates the Pauli- and self-energy shifts that are not included in the ordinary liquid drop model. The pasta phases for heavy nuclei are taken into account in the same way as in the previous model. We find that the abundances of heavy nuclei are modified by the shell effects of nuclei and temperature dependence of bulk energies. These changes may have an important effect on the rates of electron captures and coherent neutrino scatterings on nuclei in supernova cores. The abundances of light nuclei are also modified by the new mass evaluation, which may affect the heating and cooling rates of supernova cores and shocked envelopes.

Topology optimization of 3D shell structures with porous infill

NASA Astrophysics Data System (ADS)

Clausen, Anders; Andreassen, Erik; Sigmund, Ole

2017-08-01

This paper presents a 3D topology optimization approach for designing shell structures with a porous or void interior. It is shown that the resulting structures are significantly more robust towards load perturbations than completely solid structures optimized under the same conditions. The study indicates that the potential benefit of using porous structures is higher for lower total volume fractions. Compared to earlier work dealing with 2D topology optimization, we found several new effects in 3D problems. Most notably, the opportunity for designing closed shells significantly improves the performance of porous structures due to the sandwich effect. Furthermore, the paper introduces improved filter boundary conditions to ensure a completely uniform coating thickness at the design domain boundary.

Structural transformation and photoluminescence modification of AgInS2 nanoparticles induced by ZnS shell formation

NASA Astrophysics Data System (ADS)

Hamanaka, Yasushi; Yukitoki, Daichi; Kuzuya, Toshihiro

2015-09-01

AgInS2 nanoparticles were capped by ZnS via a widely used procedure to fabricate core/shell nanoparticles with highly efficient luminescence. The nanoparticle structures were investigated by ultrahigh-resolution analytical electron microscopy. We found that Zn-Ag-In-S nanoparticles were created by ZnS capping at ˜480 K, which suggests that the luminescence enhancement reported for such core/shell nanoparticles is not caused by the passivation of surface defects by ZnS shells but by Zn doping. Quasi-core/shell nanoparticles could be obtained by ZnS capping without heating. However, their luminescence efficiency remained unchanged, indicating that surface passivation was ineffective when ZnS shells were formed at room temperature.

Jammed elastic shells - a 3D experimental soft frictionless granular system

NASA Astrophysics Data System (ADS)

Jose, Jissy; Blab, Gerhard A.; van Blaaderen, Alfons; Imhof, Arnout

2015-03-01

We present a new experimental system of monodisperse, soft, frictionless, fluorescent labelled elastic shells for the characterization of structure, universal scaling laws and force networks in 3D jammed matter. The interesting fact about these elastic shells is that they can reversibly deform and therefore serve as sensors of local stress in jammed matter. Similar to other soft particles, like emulsion droplets and bubbles in foam, the shells can be packed to volume fractions close to unity, which allows us to characterize the contact force distribution and universal scaling laws as a function of volume fraction, and to compare them with theoretical predictions and numerical simulations. However, our shells, unlike other soft particles, deform rather differently at large stresses. They deform without conserving their inner volume, by forming dimples at contact regions. At each contact one of the shells buckled with a dimple and the other remained spherical, closely resembling overlapping spheres. We conducted 3D quantitative analysis using confocal microscopy and image analysis routines specially developed for these particles. In addition, we analysed the randomness of the process of dimpling, which was found to be volume fraction dependent.

Transition sum rules in the shell model

NASA Astrophysics Data System (ADS)

Lu, Yi; Johnson, Calvin W.

2018-03-01

An important characterization of electromagnetic and weak transitions in atomic nuclei are sum rules. We focus on the non-energy-weighted sum rule (NEWSR), or total strength, and the energy-weighted sum rule (EWSR); the ratio of the EWSR to the NEWSR is the centroid or average energy of transition strengths from an nuclear initial state to all allowed final states. These sum rules can be expressed as expectation values of operators, which in the case of the EWSR is a double commutator. While most prior applications of the double commutator have been to special cases, we derive general formulas for matrix elements of both operators in a shell model framework (occupation space), given the input matrix elements for the nuclear Hamiltonian and for the transition operator. With these new formulas, we easily evaluate centroids of transition strength functions, with no need to calculate daughter states. We apply this simple tool to a number of nuclides and demonstrate the sum rules follow smooth secular behavior as a function of initial energy, as well as compare the electric dipole (E 1 ) sum rule against the famous Thomas-Reiche-Kuhn version. We also find surprising systematic behaviors for ground-state electric quadrupole (E 2 ) centroids in the s d shell.

Precision measurement of the mass difference between light nuclei and anti-nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adam, J.

The measurement of the mass differences for systems bound by the strong force has reached a very high precision with protons and anti-protons. The extension of such measurement from (anti-)baryons to (anti-)nuclei allows one to probe any difference in the interactions between nucleons and anti-nucleons encoded in the (anti-)nuclei masses. Also, this force is a remnant of the underlying strong interaction among quarks and gluons and can be described by effective theories, but cannot yet be directly derived from quantum chromodynamics. Here we report a measurement of the difference between the ratios of the mass and charge of deuterons (d) and anti-deuterons (more » $$-\\atop{d}$$), and 3He and 3$$-\\atop{He}$$nuclei carried out with the ALICE (A Large Ion Collider Experiment) detector in Pb–Pb collisions at a centre-of-mass energy per nucleon pair of 2.76 TeV. Our direct measurement of the mass-over-charge differences confirms CPT invariance to an unprecedented precision in the sector of light nuclei. This fundamental symmetry of nature, which exchanges particles with anti-particles, implies that all physics laws are the same under the simultaneous reversal of charge(s) (charge conjugation C), reflection of spatial coordinates (parity transformation P) and time inversion (T).« less

Precision measurement of the mass difference between light nuclei and anti-nuclei

DOE PAGES

Adam, J.

2015-08-17

The measurement of the mass differences for systems bound by the strong force has reached a very high precision with protons and anti-protons. The extension of such measurement from (anti-)baryons to (anti-)nuclei allows one to probe any difference in the interactions between nucleons and anti-nucleons encoded in the (anti-)nuclei masses. Also, this force is a remnant of the underlying strong interaction among quarks and gluons and can be described by effective theories, but cannot yet be directly derived from quantum chromodynamics. Here we report a measurement of the difference between the ratios of the mass and charge of deuterons (d) and anti-deuterons (more » $$-\\atop{d}$$), and 3He and 3$$-\\atop{He}$$nuclei carried out with the ALICE (A Large Ion Collider Experiment) detector in Pb–Pb collisions at a centre-of-mass energy per nucleon pair of 2.76 TeV. Our direct measurement of the mass-over-charge differences confirms CPT invariance to an unprecedented precision in the sector of light nuclei. This fundamental symmetry of nature, which exchanges particles with anti-particles, implies that all physics laws are the same under the simultaneous reversal of charge(s) (charge conjugation C), reflection of spatial coordinates (parity transformation P) and time inversion (T).« less

Tables of E2 transition probabilities from the first 2 + states in even-even nuclei [B(E2) evaluation for 0 + 1 → 2 + 1 transitions in even-even nuclei

DOE PAGES

Pritychenko, B.; Birch, M.; Singh, B.; ...

2015-11-03

A complete B(E2)↑ evaluation and compilation for even-even nuclei has been presented. The present paper is a continuation of P.H. Stelson and L. Grodzins, and S. Raman et al. nuclear data evaluations and was motivated by a large number of new measurements. It extends the list of evaluated nuclides from 328 to 452, includes an extended list of nuclear reaction kinematics parameters and comprehensive shell model analysis. Evaluation policies for analysis of experimental data have been discussed and conclusions are given. Moreover, future plans for B(E2)↑ systematics and experimental technique analyses of even-even nuclei are outlined.

Au/CdS Hybrid Nanoparticles in Block Copolymer Micellar Shells.

PubMed

Koh, Haeng-Deog; Changez, Mohammad; Lee, Jae-Suk

2010-10-18

A polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) micellar structure with a P2VP core containing 5 nm CdS nanoparticles (NPs) and a PS shell formed in toluene that is a good solvent for PS block undergoes the core-shell inversion by excess addition of methanol that is a good solvent for P2VP block. It leads to the formation of micellar shell-embedded CdS NPs in the methanol major phase. The spontaneous crystalline growth of Au NPs on the CdS surfaces positioned at micellar shells without a further reduction process is newly demonstrated. The nanostructure of Au/CdS/PS-b-P2VP hybrid NPs is confirmed by transmission electron microscopy, energy-dispersive X-ray, and UV-Vis absorption. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Shell effects in a multinucleon transfer process

NASA Astrophysics Data System (ADS)

Zhu, Long; Wen, Pei-Wei; Lin, Cheng-Jian; Bao, Xiao-Jun; Su, Jun; Li, Cheng; Guo, Chen-Chen

2018-04-01

The shell effects in multinucleon transfer process are investigated in the systems 136Xe + 198Pt and 136Xe + 208Pb within the dinuclear system (DNS) model. The temperature dependence of shell corrections on potential energy surface is taken into account in the DNS model and remarkable improvement for description of experimental data is noticed. The reactions 136Xe + 186W and 150Nd + 186W are also studied. It is found that due to shell effects the projectile 150Nd is more promising for producing transtarget nuclei rather than 136Xe with neutron shell closure.

Catalytic activity in lithium-treated core–shell MoO x/MoS 2 nanowires

DOE PAGES

Cummins, Dustin R.; Martinez, Ulises; Kappera, Rajesh; ...

2015-09-22

Significant interest has grown in the development of earth-abundant and efficient catalytic materials for hydrogen generation. Layered transition metal dichalcogenides present opportunities for efficient electrocatalytic systems. Here, we report the modification of 1D MoO x/MoS 2 core–shell nanostructures by lithium intercalation and the corresponding changes in morphology, structure, and mechanism of H 2 evolution. The 1D nanowires exhibit significant improvement in H 2 evolution properties after lithiation, reducing the hydrogen evolution reaction (HER) onset potential by ~50 mV and increasing the generated current density by ~600%. The high electrochemical activity in the nanowires results from disruption of MoS 2 layersmore » in the outer shell, leading to increased activity and concentration of defect sites. This is in contrast to the typical mechanism of improved catalysis following lithium exfoliation, i.e., crystal phase transformation. As a result, these structural changes are verified by a combination of Raman and X-ray photoelectron spectroscopy (XPS).« less

Intrinsic properties of high-spin band structures in triaxial nuclei

NASA Astrophysics Data System (ADS)

Jehangir, S.; Bhat, G. H.; Sheikh, J. A.; Palit, R.; Ganai, P. A.

2017-12-01

The band structures of 68,70Ge, 128,130,132,134Ce and 132,134,136,138Nd are investigated using the triaxial projected shell model (TPSM) approach. These nuclei depict forking of the ground-state band into several s-bands and in some cases, both the lowest two observed s-bands depict neutron or proton character. It was discussed in our earlier work that this anomalous behaviour can be explained by considering γ-bands based on two-quasiparticle configurations. As the parent band and the γ-band built on it have the same intrinsic structure, g-factors of the two bands are expected to be similar. In the present work, we have undertaken a detailed investigation of g-factors for the excited band structures of the studied nuclei and the available data for a few high-spin states are shown to be in fair agreement with the predicted values.

Measurement of elliptic flow of light nuclei at s N N = 200 , 62.4, 39, 27, 19.6, 11.5, and 7.7 GeV at the BNL Relativistic Heavy Ion Collider

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adamczyk, L.; Adkins, J. K.; Agakishiev, G.

Here we present measurements of second-order azimuthal anisotropy ( v 2 ) at midrapidity ( |y| < 1.0 ) for light nuclei d , t , 3He (formore » $$\\sqrt{s}$$$_{NN}$$ = 200 , 62.4, 39, 27, 19.6, 11.5, and 7.7 GeV) and antinuclei$$\\bar{d}$$ ( $$\\sqrt{s}$$$_{NN}$$ = 200 , 62.4, 39, 27, and 19.6 GeV) and 3 ¯¯¯¯¯ He ( $$\\sqrt{s}$$$_{NN}$$ = 200 GeV) in the STAR (Solenoidal Tracker at RHIC) experiment. The v 2 for these light nuclei produced in heavy-ion collisions is compared with those for p and $$\\bar{p}$$. We observe mass ordering in nuclei v 2 ( p T) at low transverse momenta ( p T < 2.0 GeV/c). We also find a centrality dependence of v 2 for d and $$\\bar{d}$$ . The magnitude of v 2 for t and 3He agree within statistical errors. Light-nuclei v 2 are compared with predictions from a blast-wave model. Atomic mass number ( A ) scaling of light-nuclei v 2 (p T) seems to hold for p T / A < 1.5 GeV/c . Results on light-nuclei v 2 from a transport-plus-coalescence model are consistent with the experimental measurements.« less

Measurement of elliptic flow of light nuclei at s N N = 200 , 62.4, 39, 27, 19.6, 11.5, and 7.7 GeV at the BNL Relativistic Heavy Ion Collider

DOE PAGES

Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; ...

2016-09-23

Here we present measurements of second-order azimuthal anisotropy ( v 2 ) at midrapidity ( |y| < 1.0 ) for light nuclei d , t , 3He (formore » $$\\sqrt{s}$$$_{NN}$$ = 200 , 62.4, 39, 27, 19.6, 11.5, and 7.7 GeV) and antinuclei$$\\bar{d}$$ ( $$\\sqrt{s}$$$_{NN}$$ = 200 , 62.4, 39, 27, and 19.6 GeV) and 3 ¯¯¯¯¯ He ( $$\\sqrt{s}$$$_{NN}$$ = 200 GeV) in the STAR (Solenoidal Tracker at RHIC) experiment. The v 2 for these light nuclei produced in heavy-ion collisions is compared with those for p and $$\\bar{p}$$. We observe mass ordering in nuclei v 2 ( p T) at low transverse momenta ( p T < 2.0 GeV/c). We also find a centrality dependence of v 2 for d and $$\\bar{d}$$ . The magnitude of v 2 for t and 3He agree within statistical errors. Light-nuclei v 2 are compared with predictions from a blast-wave model. Atomic mass number ( A ) scaling of light-nuclei v 2 (p T) seems to hold for p T / A < 1.5 GeV/c . Results on light-nuclei v 2 from a transport-plus-coalescence model are consistent with the experimental measurements.« less

Are Pericentric Inversions Reorganizing Wedge Shell Genomes?

PubMed Central

García-Souto, Daniel; Pérez-García, Concepción

2017-01-01

Wedge shells belonging to the Donacidae family are the dominant bivalves in exposed beaches in almost all areas of the world. Typically, two or more sympatric species of wedge shells differentially occupy intertidal, sublittoral, and offshore coastal waters in any given locality. A molecular cytogenetic analysis of two sympatric and closely related wedge shell species, Donax trunculus and Donax vittatus, was performed. Results showed that the karyotypes of these two species were both strikingly different and closely alike; whilst metacentric and submetacentric chromosome pairs were the main components of the karyotype of D. trunculus, 10–11 of the 19 chromosome pairs were telocentric in D. vittatus, most likely as a result of different pericentric inversions. GC-rich heterochromatic bands were present in both species. Furthermore, they showed coincidental 45S ribosomal RNA (rRNA), 5S rRNA and H3 histone gene clusters at conserved chromosomal locations, although D. trunculus had an additional 45S rDNA cluster. Intraspecific pericentric inversions were also detected in both D. trunculus and D. vittatus. The close genetic similarity of these two species together with the high degree of conservation of the 45S rRNA, 5S rRNA and H3 histone gene clusters, and GC-rich heterochromatic bands indicate that pericentric inversions contribute to the karyotype divergence in wedge shells. PMID:29215567

Lifetime of inner-shell hole states of Ar (2p) and Kr (3d) using equation-of-motion coupled cluster method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghosh, Aryya; Vaval, Nayana, E-mail: np.vaval@ncl.res.in; Pal, Sourav

2015-07-14

Auger decay is an efficient ultrafast relaxation process of core-shell or inner-shell excited atom or molecule. Generally, it occurs in femto-second or even atto-second time domain. Direct measurement of lifetimes of Auger process of single ionized and double ionized inner-shell state of an atom or molecule is an extremely difficult task. In this paper, we have applied the highly correlated complex absorbing potential-equation-of-motion coupled cluster (CAP-EOMCC) approach which is a combination of CAP and EOMCC approach to calculate the lifetime of the states arising from 2p inner-shell ionization of an Ar atom and 3d inner-shell ionization of Kr atom. Wemore » have also calculated the lifetime of Ar{sup 2+}(2p{sup −1}3p{sup −1}) {sup 1}D, Ar{sup 2+}(2p{sup −1}3p{sup −1}) {sup 1}S, and Ar{sup 2+}(2p{sup −1}3s{sup −1}) {sup 1}P double ionized states. The predicted results are compared with the other theoretical results as well as experimental results available in the literature.« less

{gamma}-vibrational states in superheavy nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun Yang; Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000; Joint Institute for Nuclear Astrophysics, University of Notre Dame, Notre Dame, Indiana 46556

2008-04-15

Recent experimental advances have made it possible to study excited structure in superheavy nuclei. The observed states have often been interpreted as quasiparticle excitations. We show that in superheavy nuclei collective vibrations systematically appear as low-energy excitation modes. By using the microscopic Triaxial Projected Shell Model, we make a detailed prediction on {gamma}-vibrational states and their E2 transition probabilities to the ground state band in fermium and nobelium isotopes where active structure research is going on, and in {sup 270}Ds, the heaviest isotope where decay data have been obtained for the ground-state and for an isomeric state.

Double-shell CuS nanocages as advanced supercapacitor electrode materials

NASA Astrophysics Data System (ADS)

Guo, Jinxue; Zhang, Xinqun; Sun, Yanfang; Zhang, Xiaohong; Tang, Lin; Zhang, Xiao

2017-07-01

Metal sulfides hollow structures are advanced materials for energy storage applications of lithium-ion batteries and supercapacitors. However, constructing hollow metal sulfides with specific features, such as multi-shell and non-spherical shape, still remains great challenge. In this work, we firstly demonstrate the synthesis of CuS double-shell hollow nanocages using Cu2O nanocubes as precursors. The synthesis processes involve the repeated anion exchange reaction with Na2S and the controllable etching using hydrochloric acid. The whole synthesis processes are well revealed and the obtained double-shell CuS is tested as pseudocapacitive electrode material for supercapacitors. As expected, the CuS double-shell hollow nanocages deliver high specific capacitance, good rate performance and excellent cycling stability due to their unique nano-architecture. The present work contributes greatly to the exploration of hollow metal sulfides with complex architecture and non-spherical shape, as well as their promising application in high-performance electrochemical supercapacitors.

Measurement of elliptic flow of light nuclei at √{sN N}=200 , 62.4, 39, 27, 19.6, 11.5, and 7.7 GeV at the BNL Relativistic Heavy Ion Collider

NASA Astrophysics Data System (ADS)

Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Attri, A.; Averichev, G. S.; Bai, X.; Bairathi, V.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandenburg, J. D.; Brandin, A. V.; Bunzarov, I.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chatterjee, A.; Chattopadhyay, S.; Chen, J. H.; Chen, X.; Cheng, J.; Cherney, M.; Christie, W.; Contin, G.; Crawford, H. J.; Das, S.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; di Ruzza, B.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Eppley, G.; Esha, R.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Fedorisin, J.; Feng, Z.; Filip, P.; Fisyak, Y.; Flores, C. E.; Fulek, L.; Gagliardi, C. A.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, S.; Gupta, A.; Guryn, W.; Hamad, A. I.; Hamed, A.; Haque, R.; Harris, J. W.; He, L.; Heppelmann, S.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Horvat, S.; Huang, T.; Huang, X.; Huang, B.; Huang, H. Z.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Jentsch, A.; Jia, J.; Jiang, K.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Khan, Z. H.; Kikoła, D. P.; Kisel, I.; Kisiel, A.; Kochenda, L.; Koetke, D. D.; Kosarzewski, L. K.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kumar, L.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Li, X.; Li, C.; Li, X.; Li, Y.; Li, W.; Lin, T.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, R.; Ma, G. L.; Ma, Y. G.; Ma, L.; Magdy, N.; Majka, R.; Manion, A.; Margetis, S.; Markert, C.; Matis, H. S.; McDonald, D.; McKinzie, S.; Meehan, K.; Mei, J. C.; Minaev, N. G.; Mioduszewski, S.; Mishra, D.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nigmatkulov, G.; Niida, T.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V. A.; Olvitt, D.; Page, B. S.; Pak, R.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlik, B.; Pei, H.; Perkins, C.; Pile, P.; Pluta, J.; Poniatowska, K.; Porter, J.; Posik, M.; Poskanzer, A. M.; Pruthi, N. K.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, M. K.; Sharma, B.; Shen, W. Q.; Shi, Z.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Sikora, R.; Simko, M.; Singha, S.; Skoby, M. J.; Smirnov, N.; Smirnov, D.; Solyst, W.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stepanov, M.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Summa, B.; Sun, X. M.; Sun, Z.; Sun, Y.; Surrow, B.; Svirida, D. N.; Tang, Z.; Tang, A. H.; Tarnowsky, T.; Tawfik, A.; Thäder, J.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Todoroki, T.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Tsai, O. D.; Ullrich, T.; Underwood, D. G.; Upsal, I.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Varma, R.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, Y.; Wang, G.; Wang, J. S.; Wang, H.; Wang, Y.; Wang, F.; Webb, G.; Webb, J. C.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y.; Xiao, Z. G.; Xie, W.; Xie, G.; Xin, K.; Xu, H.; Xu, Z.; Xu, J.; Xu, Y. F.; Xu, Q. H.; Xu, N.; Yang, Y.; Yang, S.; Yang, C.; Yang, Y.; Yang, Y.; Yang, Q.; Ye, Z.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, J.; Zhang, Y.; Zhang, X. P.; Zhang, Z.; Zhang, J. B.; Zhang, S.; Zhang, S.; Zhang, J.; Zhao, J.; Zhong, C.; Zhou, L.; Zhu, X.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration

2016-09-01

We present measurements of second-order azimuthal anisotropy (v2) at midrapidity (|y |<1.0 ) for light nuclei d ,t ,3He (for √{sN N}=200 , 62.4, 39, 27, 19.6, 11.5, and 7.7 GeV) and antinuclei d ¯ (√{sN N}=200 , 62.4, 39, 27, and 19.6 GeV) and ¯3He (√{sN N}=200 GeV) in the STAR (Solenoidal Tracker at RHIC) experiment. The v2 for these light nuclei produced in heavy-ion collisions is compared with those for p and p ¯. We observe mass ordering in nuclei v2(pT) at low transverse momenta (pT<2.0 GeV/c ). We also find a centrality dependence of v2 for d and d ¯. The magnitude of v2 for t and 3He agree within statistical errors. Light-nuclei v2 are compared with predictions from a blast-wave model. Atomic mass number (A ) scaling of light-nuclei v2(pT) seems to hold for pT/A <1.5 GeV /c . Results on light-nuclei v2 from a transport-plus-coalescence model are consistent with the experimental measurements.

Structural and electronic properties of CdS/ZnS core/shell nanowires: A first-principles study

NASA Astrophysics Data System (ADS)

Kim, Hyo Seok; Kim, Yong-Hoon

2015-03-01

Carrying out density functional theory (DFT) calculation, we studied the relative effects of quantum confinement and strain on the electronic structures of II-IV semiconductor compounds with a large lattice-mismatch, CdS and ZnS, in the core/shell nanowire geometry. We considered different core radii and shell thickness of the CdS/ZnS core/shell nanowire, different surface facets, and various defects in the core/shell interface and surface regions. To properly describe the band level alignment at the core/shell boundary, we adopted the self-interaction correction (SIC)-DFT scheme. Implications of our findings in the context of device applications will be also discussed. This work was supported by the Basic Science Research Grant (No. 2012R1A1A2044793), Global Frontier Program (No. 2013-073298), and Nano-Material Technology Development Program (2012M3A7B4049888) of the National Research Foundation funded by the Ministry of Education, Science and Technology of Korea. Corresponding author

Interplay of spherical closed shells and N /Z asymmetry in quasifission dynamics

NASA Astrophysics Data System (ADS)

Mohanto, G.; Hinde, D. J.; Banerjee, K.; Dasgupta, M.; Jeung, D. Y.; Simenel, C.; Simpson, E. C.; Wakhle, A.; Williams, E.; Carter, I. P.; Cook, K. J.; Luong, D. H.; Palshetkar, C. S.; Rafferty, D. C.

2018-05-01

Background: Quasifission (QF) has gained tremendous importance in heavy-ion nuclear physics research because of its strong influence on superheavy-element synthesis. Collisions involving closed-shell nuclei in the entrance channel are found to affect the QF reaction mechanism. Hence, it is important to improve the understanding of their effect on QF. Apart from that, some recent studies show that the difference in N /Z of reaction partners influences the reaction dynamics. Since heavier doubly magic nuclei have different N /Z than lighter doubly magic nuclei, it is important to understand the effect of N /Z mismatch as well as the effect of shell closures. Purpose: To investigate the effect of entrance-channel shell closures and N /Z asymmetry on QF. The reactions were chosen to decouple these effects from the contributions of other entrance-channel parameters. Method: Fission fragment mass-angle distributions were measured using the CUBE fission spectrometer, consisting of two large area position-sensitive multi-wire proportional counters (MWPCs), for five reactions, namely, 50Cr+208Pb , 52Cr+Pb,208206 , 54Cr+Pb,208204 . Result: Two components were observed in the measured fragment mass angle distribution, a fast mass-asymmetric quasifission and a slow mass-symmetric component having a less significant mass-angle correlation. The ratio of these components was found to depend on spherical closed shells in the entrance channel nuclei and the magnitude of the N /Z mismatch between the two reaction partners, as well as the beam energy. Conclusions: Entrance-channel spherical closed shells can enhance compound nucleus formation provided the N /Z asymmetry is small. Increase in the N /Z asymmetry is expected to destroy the effect of entrance-channel spherical closed shells, through nucleon transfer reactions.

The Origin of the s, p, d, f Orbital Labels

ERIC Educational Resources Information Center

Jensen, William B.

2007-01-01

The theory of s, p, d and f dealing with the line spectra of the alkali metals during the period 1881 based on analogies with the harmonic ratios of sound is described. Friedrich Hund followed Bohr's practice of labelling the various shells and subshells by replacing the secondary quantum number with the series notations (s, p, d, and f), which…

Deformed shell model calculations of half lives for β+/EC decay and 2ν β+β+/β+EC/ECEC decay in medium-heavy N~Z nuclei

NASA Astrophysics Data System (ADS)

Mishra, S.; Shukla, A.; Sahu, R.; Kota, V. K. B.

2008-08-01

The β+/EC half-lives of medium heavy N~Z nuclei with mass number A~64-80 are calculated within the deformed shell model (DSM) based on Hartree-Fock states by employing a modified Kuo interaction in (2p3/2,1f5/2,2p1/2,1g9/2) space. The DSM model has been quite successful in predicting many spectroscopic properties of N~Z medium heavy nuclei with A~64-80. The calculated β+/EC half-lives, for prolate and oblate shapes, compare well with the predictions of the calculations with Skyrme force by Sarriguren Going further, following recent searches, half-lives for 2ν β+β+/β+EC/ECEC decay for the nucleus Kr78 are calculated using DSM and the results compare well with QRPA predictions.

What is hiding behind ontogenic d13C variations in mollusk shells: New insights from scallops.

NASA Astrophysics Data System (ADS)

Chauvaud, L.; Lorrain, A.; Gillikin, D. P.; Thebault, J.; Paulet, Y.; Strand, O.; Blamart, D.; Guarini, J.; Clavier, J.

2008-12-01

We examined d13Ccalcite variations along scallop shells (Pecten maximus) sampled in Norway, France and Spain. Time series of shell calcite d13C show a consistent pattern of decreasing d13C with age. This almost linear d13C trend reflects an increasing contribution of metabolic CO2 to skeletal carbonate throughout ontogeny. We have removed this ontogenic trend to try to extract other information from our shell calcite d13C dataset. Scallops from the Bay of Brest (western Brittany, France) were then used to interpret the data as many environmental parameters were available for this site. d13Ccalcite variations were compared to d13C of dissolved inorganic carbon (DIC) and Chl a. The detrended calcite d13C profiles seem to follow a seasonal pattern, but surprisingly are inversely related to the d13C DIC and chlorophyll a concentrations measured within the water column. Theses results suggest that shell d13C variations are not controlled by isotopic variation of DIC. Since scallops eat phytoplankton and microphytobenthos cells, and, as a consequence respire organic mater largely depleted in 13C, we therefore suggest that in mollusk suspension feeders the shell d13Ccalcite might still be used to track the annual number of phytoplankton blooms when d13C values of calcite are detrended. We must consider this trend as a potential biological filter hiding precious environmental records.

17 CFR 240.15d-19 - Reports by shell companies on Form 20-F.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Reports by shell companies on... Under the Securities Exchange Act of 1934 Other Reports § 240.15d-19 Reports by shell companies on Form 20-F. Every foreign private issuer that was a shell company, other than a business combination...

17 CFR 240.15d-19 - Reports by shell companies on Form 20-F.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 17 Commodity and Securities Exchanges 3 2011-04-01 2011-04-01 false Reports by shell companies on... Under the Securities Exchange Act of 1934 Other Reports § 240.15d-19 Reports by shell companies on Form 20-F. Every foreign private issuer that was a shell company, other than a business combination...

Application of the Shell/3D Modeling Technique for the Analysis of Skin-Stiffener Debond Specimens

NASA Technical Reports Server (NTRS)

Krueger, Ronald; O'Brien, T. Kevin; Minguet, Pierre J.

2002-01-01

The application of a shell/3D modeling technique for the simulation of skin/stringer debond in a specimen subjected to three-point bending is demonstrated. The global structure was modeled with shell elements. A local three-dimensional model, extending to about three specimen thicknesses on either side of the delamination front was used to capture the details of the damaged section. Computed total strain energy release rates and mixed-mode ratios obtained from shell/13D simulations were in good agreement with results obtained from full solid models. The good correlations of the results demonstrated the effectiveness of the shell/3D modeling technique for the investigation of skin/stiffener separation due to delamination in the adherents.

Dielectronic Recombination In Active Galactic Nuclei

NASA Technical Reports Server (NTRS)

Lukic, D. V.; Schnell, M.; Savin, D. W.; Altun, Z.; Badnell, N.; Brandau, C.; Schmidt, E. W.; Mueller, A.; Schippers, S.; Sprenger, F.;

FUSTIPEN—the France-U.S. Theory Institute for Physics with Exotic Nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Papenbrock, Thomas

FUSTIPEN, the France-U.S. Theory Institute for Physics with Exotic Nuclei, was an international venue for theoretical research on the physics of nuclei during an era of particularly active experimental investigations of rare isotopes, see http://fustipen.ganil.fr/. It was dedicated to collaborative research between U.S.-based and French nuclear physicists, drawing on the complementary expertise in the two countries. The grant provided travel and local support for visits by U.S. nuclear physicists to GANIL, where the FUSTIPEN offices are located, and also supported collateral travel to other French research institutions.

Helium-Shell Nucleosynthesis and Extinct Radioactivities

NASA Technical Reports Server (NTRS)

Meyer, B. S.; The, L.-S.; Clayton, D. D.; ElEid, M. F.

2004-01-01

Although the exact site for the origin of the r-process isotopes remains mysterious, most thinking has centered on matter ejected from the cores of massive stars in core-collapse supernovae [13]. In the 1970's and 1980's, however, difficulties in understanding the yields from such models led workers to consider the possibility of r-process nucleosynthesis farther out in the exploding star, in particular, in the helium burning shell [4,5]. The essential idea was that shock passage through this shell would heat and compress this material to the point that the reactions 13C(alpha; n)16O and, especially, 22Ne(alpha; n)25Mg would generate enough neutrons to capture on preexisting seed nuclei and drive an "n process" [6], which could reproduce the r-process abundances. Subsequent work showed that the required 13C and 22Ne abundances were too large compared to the amounts available in realistic models [7] and recent thinking has returned to supernova core material or matter ejected from neutron star-neutron star collisions as the more likely r-process sites.

Landscape of α preformation probability for even-even nuclei in medium mass region

NASA Astrophysics Data System (ADS)

Qian, Yibin; Ren, Zhongzhou

2018-03-01

The behavior of α cluster preformation probability, in α decay, is a rich source of the structural information, such as the clustering, pairing, and shell evolution in heavy nuclei. Meanwhile, the experimental α decay data have been very recently compiled in the newest table NUBASE2016. Through a least square fit to the available experimental data of nuclear charge radii plus the neutron skin thickness, we obtain a new set of parameters for the two-parameter Fermi nucleon density distributions in target nuclei. Subsequently, we make use of these refreshed inputs, involved in the density-dependent cluster model, to extract α preformation factor ({P}α ) for a large range of medium α emitters with N < 126 from the newest data table. Besides checking the supposed smooth pattern of P α in the open-shell region, the special attention has been paid to those exotic α-decaying nuclei around the Z = 50 and N = 82 shell closures. Moreover, the correlation between the α preformation factor and the microscopic correction of nuclear mass, corresponding to the effect of shell and pairing plus deformation, is in particular investigated, to pursue the valuable knowledge of the P α pattern over the nuclide chart. The feature of α preformation factor along with the neutron-proton asymmetry is then detected and discussed to some extent.

Composted oyster shell as lime fertilizer is more effective than fresh oyster shell.

PubMed

Lee, Young Han; Islam, Shah Md Asraful; Hong, Sun Joo; Cho, Kye Man; Math, Renukaradhya K; Heo, Jae Young; Kim, Hoon; Yun, Han Dae

2010-01-01

Physio-chemical changes in oyster shell were examined, and fresh and composted oyster shell meals were compared as lime fertilizers in soybean cultivation. Structural changes in oyster shell were observed by AFM and FE-SEM. We found that grains of the oyster shell surface became smoother and smaller over time. FT-IR analysis indicated the degradation of a chitin-like compound of oyster shell. In chemical analysis, pH (12.3+/-0.24), electrical conductivity (4.1+/-0.24 dS m(-1)), and alkaline powder (53.3+/-1.12%) were highest in commercial lime. Besides, pH was higher in composted oyster shell meal (9.9+/-0.53) than in fresh oyster shell meal (8.4+/-0.32). The highest organic matter (1.1+/-0.08%), NaCl (0.54+/-0.03%), and moisture (15.1+/-1.95%) contents were found in fresh oyster shell meal. A significant higher yield of soybean (1.33 t ha(-1)) was obtained by applying composted oyster shell meal (a 21% higher yield than with fresh oyster shell meal). Thus composting of oyster shell increases the utility of oyster shell as a liming material for crop cultivation.

Computational studies of the 2D self-assembly of bacterial microcompartment shell proteins

NASA Astrophysics Data System (ADS)

Mahalik, Jyoti; Brown, Kirsten; Cheng, Xiaolin; Fuentes-Cabrera, Miguel

Bacterial microcomartments (BMCs) are subcellular organelles that exist within wide variety of bacteria and function like nano-reactors. Among the different types of BMCs known, the carboxysome has been studied the most. The carboxysomes plays an important role in the transport of metabolites across its outer proteinaceous shell. Plenty of studies have investigated the structure of this shell, yet little is known about its self-assembly . Understanding the self-assembly process of BMCs' shell might allow disrupting their functioning and designing new synthetic nano-reactors. We have investigated the self-assembly process of a major protein component of the carboxysome's shell using a Monte Carlo technique that employed a coarse-grained protein model that was calibrated with the all-atomistic potential of mean force. The simulations reveal that this protein self-assembles into clusters that resemble what were seen experimentally in 2D layers. Further analysis of the simulation results suggests that the 2D self-assembly of carboxysome's facets is driven by nucleation-growth process, which in turn could play an important role in the hierarchical self-assembly of BMCs' shell in general. 1. Science Undergraduate Laboratory Internships, ORNL 2. Oak Ridge Leadership Computing Facility, ORNL.

A systematic study of superheavy nuclei for Z = 114 and beyond using the relativistic mean field approach

NASA Astrophysics Data System (ADS)

Patra, S. K.; Wu, Cheng-Li; Praharaj, C. R.; Gupta, Raj K.

1999-05-01

We have studied the structural properties of even-even, neutron deficient, Z = 114-126, superheavy nuclei in the mass region A ˜ 270-320, using an axially deformed relativistic mean field model. The calculations are performed with three parameter sets (NL1, TM1 and NL-SH), in order to see the dependence of the structural properties on the force used. The calculated ground state shapes are found to be parameter dependent. For some parameter sets, many of the nuclei are degenerate in their ground state configuration. Special attention is given to the investigation of the magic structures (spherical shell closures) in the superheavy region. We find that some known magic numbers are absent and new closed shells are predicted. Large shell gaps appear at Z = 80, 92, (114), 120 and 138, N = 138, (164), (172), 184, (198), (228) and 258, irrespective of the parameter sets used. The numbers in parenthesis are those which correspond to relatively smaller gaps. The existence of new magic numbers in the valley of superheavy elements is discussed. It is suggested that nuclei around Z = 114 and N = 164 ˜ 172 could be considered as candidates for the next search of superheavy nuclei. The existence of superheavy islands around Z = 120 and N = 172 or N = 184 double shell closure is also discussed.

The s-process in massive stars: the Shell C-burning contribution

NASA Astrophysics Data System (ADS)

Pignatari, Marco; Gallino, R.; Baldovin, C.; Wiescher, M.; Herwig, F.; Heger, A.; Heil, M.; Käppeler, F.

In massive stars the s¡ process (slow neutron capture process) is activated at different tempera- tures, during He¡ burning and during convective shell C¡ burning. At solar metallicity, the neu- tron capture process in the convective C¡ shell adds a substantial contribution to the s¡ process yields made by the previous core He¡ burning, and the final results carry the signature of both processes. With decreasing metallicity, the contribution of the C¡ burning shell to the weak s¡ process rapidly decreases, because of the effect of the primary neutron poisons. On the other hand, also the s¡ process efficiency in the He core decreases with metallicity.

Defining multiple, distinct, and shared spatiotemporal patterns of DNA replication and endoreduplication from 3D image analysis of developing maize (Zea mays L.) root tip nuclei.

PubMed

Bass, Hank W; Hoffman, Gregg G; Lee, Tae-Jin; Wear, Emily E; Joseph, Stacey R; Allen, George C; Hanley-Bowdoin, Linda; Thompson, William F

2015-11-01

Spatiotemporal patterns of DNA replication have been described for yeast and many types of cultured animal cells, frequently after cell cycle arrest to aid in synchronization. However, patterns of DNA replication in nuclei from plants or naturally developing organs remain largely uncharacterized. Here we report findings from 3D quantitative analysis of DNA replication and endoreduplication in nuclei from pulse-labeled developing maize root tips. In both early and middle S phase nuclei, flow-sorted on the basis of DNA content, replicative labeling was widely distributed across euchromatic regions of the nucleoplasm. We did not observe the perinuclear or perinucleolar replicative labeling patterns characteristic of middle S phase in mammals. Instead, the early versus middle S phase patterns in maize could be distinguished cytologically by correlating two quantitative, continuous variables, replicative labeling and DAPI staining. Early S nuclei exhibited widely distributed euchromatic labeling preferentially localized to regions with weak DAPI signals. Middle S nuclei also exhibited widely distributed euchromatic labeling, but the label was preferentially localized to regions with strong DAPI signals. Highly condensed heterochromatin, including knobs, replicated during late S phase as previously reported. Similar spatiotemporal replication patterns were observed for both mitotic and endocycling maize nuclei. These results revealed that maize euchromatin exists as an intermingled mixture of two components distinguished by their condensation state and replication timing. These different patterns might reflect a previously described genome organization pattern, with "gene islands" mostly replicating during early S phase followed by most of the intergenic repetitive regions replicating during middle S phase.

Maria Goeppert Mayer, the Nuclear Shell Structure, and Magic Numbers

Science.gov Websites

dropdown arrow Site Map A-Z Index Menu Synopsis Maria Goeppert-Mayer, the Nuclear Shell Model, and Magic explanation of how neutrons and protons within atomic nuclei are structured. Called the "nuclear shell American husband, chemical physicist Joseph Mayer. At Argonne, Goeppert-Mayer learned most of her nuclear

Some special features of Wigner’s mass formula for nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nurmukhamedov, A. M., E-mail: fattah52@mail.ru

2014-12-15

Experimental data on anomalous values of the empirical function b(A) in Wigner’s mass formula are presented, the application of Student’s t criterion in experimentally proving the restoration of Wigner’s SU(4) symmetry in nuclei is validated, and a physical interpretation of the basic parameter of the empirical function a(A) in Wigner’s mass formula is given.

Test of the combined method for extracting spectroscopic factors in N =50 nuclei

NASA Astrophysics Data System (ADS)

Walter, David; Cizewski, J. A.; Baugher, T.; Ratkiewicz, A.; Pain, S. D.; Nunes, F. M.; Ahn, S.; Cerizza, G.; Jones, K. L.; Manning, B.; Thornsberry, C.

2017-09-01

The single-particle properties of nuclei near shell closures and r-process waiting points can be observed using single-nucleon transfer reactions with beams of rare isotopes. However, approximations have to be made about the final bound state to extract spectroscopic information. An approach to constrain the bound state potential has been proposed by Mukhamedzhanov and Nunes. At peripheral reaction energies ( 5 MeV/u), the ANC for the nucleus can be extracted, and is combined with the same reaction at higher energies ( 40 MeV/u). These combined measurements can constrain the shape of the bound state potential, and the spectroscopic factor can be reliably extracted. To test this method, the 86Kr(d , p) reaction was performed in inverse kinematics with a 35 MeV/u beam at the National Superconducting Cyclotron Laboratory (NSCL) with the ORRUBA and SIDAR arrays of silicon strip detectors coupled to the S800 spectrometer. Successful results supported the measurement of a radioactive ion beam of 84Se at 45 MeV/u at the NSCL to be measured at the end of 2017. Results from the 86Kr(d , p) measurement will be presented as well as preparations for the upcoming 84Se(d , p) measurement. This work is supported in part by the National Science Foundation and U.S. D.O.E.

Pemex to acquire interest in Shell Texas refinery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1992-08-31

This paper reports that Petroleos Mexicanos and Shell Oil Co. have signed a memorandum of understanding to form a joint refining venture involving Shell's 225,000 b/d Deer Park, Tex., refinery. Under the agreement, Mexico's state owned oil company is to purchase a 50% interest in the refinery, and Shell is to sell Pemex unleaded gasoline on a long term basis. Under the venture, Shell and Pemex plan to add undisclosed conversion and upgrading units tailored to process heavy Mexican crude. The revamp will allow Pemex to place more than 100,000 b/d of Mayan heavy crude on the U.S. market. Mayanmore » accounts for 70% of Mexico's crude oil exports. In turn, Shell will sell Pemex as much as 45,000 b/d of unleaded gasoline to help meet Mexico's rapidly growing demand.« less

The Design of 3D-Printed Lattice-Reinforced Thickness-Varying Shell Molds for Castings.

PubMed

Shangguan, Haolong; Kang, Jinwu; Yi, Jihao; Zhang, Xiaochuan; Wang, Xiang; Wang, Haibin; Huang, Tao

2018-03-30

3D printing technologies have been used gradually for the fabrication of sand molds and cores for castings, even though these molds and cores are dense structures. In this paper, a generation method for lattice-reinforced thickness-varying shell molds is proposed and presented. The first step is the discretization of the STL (Stereo Lithography) model of a casting into finite difference meshes. After this, a shell is formed by surrounding the casting with varying thickness, which is roughly proportional to the surface temperature distribution of the casting that is acquired by virtually cooling it in the environment. A regular lattice is subsequently constructed to support the shell. The outside surface of the shell and lattice in the cubic mesh format is then converted to STL format to serve as the external surface of the new shell mold. The internal surface of the new mold is the casting's surface with the normals of all of the triangles in STL format reversed. Experimental verification was performed on an Al alloy wheel hub casting. Its lattice-reinforced thickness-varying shell mold was generated by the proposed method and fabricated by the binder jetting 3D printing. The poured wheel hub casting was sound and of good surface smoothness. The cooling rate of the wheel hub casting was greatly increased due to the shell mold structure. This lattice-reinforced thickness-varying shell mold generation method is of great significance for mold design for castings to achieve cooling control.

Wide emission-tunable CdTeSe/ZnSe/ZnS core–shell quantum dots and their conjugation with E. coli O-157

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Haifeng; Zhou, Guangjun, E-mail: gjzhou@sdu.edu.cn; Zhou, Juan

2015-05-15

Highlights: • QDs with variety morphology were obtained via an injection controlled process. • 3-D PL spectra of core–shell QDs show different excitation wavelength dependence. • The PL intensity of QDs with ZnSe transition layer increases dramatically. • Core–shell QDs were processed into aqueous phase and conjugated with E. coli O-157. - Abstract: Wide emission-tunable and different morphological alloyed CdTeSe quantum dots (QDs), CdTeSe/ZnS and CdTeSe/ZnSe/ZnS core–shell QDs were successfully synthesized via an injection controlled process. The effect of injection procedure and reaction temperature were systematically discussed and the growth mechanism was proposed. Most efficient PL wavelength was correlated withmore » reaction time and temperature. The 3-D PL spectra of spherical bare CdTeSe and core–shell QDs with different passivation showed different excitation wavelength dependency. The PL intensity of CdTeSe/ZnSe/ZnS core–shell QDs increased greatly in comparison with that of CdTeSe and CdTeSe/ZnSe QDs. ZnSe transition layer played an important role in improving the PL intensity by providing a smoothened interface and gradient band offsets. The core–shell QDs were transferred into aqueous phase and successfully conjugated with Escherichia coli O-157. The proposed phase-transfer and bio-labeling strategy may be applicable to various QDs with different compositions.« less

Magnetic moments of light nuclei from lattice quantum chromodynamics

DOE PAGES

Beane, S.  R.; Chang, E.; Cohen, S.; ...

2014-12-16

We present the results of lattice QCD calculations of the magnetic moments of the lightest nuclei, the deuteron, the triton and 3He, along with those of the neutron and proton. These calculations, performed at quark masses corresponding to m π ~ 800 MeV, reveal that the structure of these nuclei at unphysically heavy quark masses closely resembles that at the physical quark masses. We find that the magnetic moment of 3He differs only slightly from that of a free neutron, as is the case in nature, indicating that the shell-model configuration of two spin-paired protons and a valence neutron capturesmore » its dominant structure. Similarly a shell-model-like moment is found for the triton, μ 3H ~ μ p. The deuteron magnetic moment is found to be equal to the nucleon isoscalar moment within the uncertainties of the calculations.« less

Mode-locked Er-doped fiber laser based on PbS/CdS core/shell quantum dots as saturable absorber.

PubMed

Ming, Na; Tao, Shina; Yang, Wenqing; Chen, Qingyun; Sun, Ruyi; Wang, Chang; Wang, Shuyun; Man, Baoyuan; Zhang, Huanian

2018-04-02

Previously, PbS/CdS core/shell quantum dots with excellent optical properties have been widely used as light-harvesting materials in solar cell and biomarkers in bio-medicine. However, the nonlinear absorption characteristics of PbS/CdS core/shell quantum dots have been rarely investigated. In this work, PbS/CdS core/shell quantum dots were successfully employed as nonlinear saturable absorber (SA) for demonstrating a mode-locked Er-doped fiber laser. Based on a film-type SA, which was prepared by incorporating the quantum dots with the polyvinyl alcohol (PVA), mode-locked Er-doped operation with a pulse width of 54 ps and a maximum average output power of 2.71 mW at the repetition rate of 3.302 MHz was obtained. Our long-time stable results indicate that the CdS shell can effectively protect the PbS core from the effect of photo-oxidation and PbS/CdS core/shell quantum dots were efficient SA candidates for demonstrating pulse fiber lasers due to its tunable absorption peak and excellent saturable absorption properties.

Chaos in nuclei: Theory and experiment

NASA Astrophysics Data System (ADS)

Muñoz, L.; Molina, R. A.; Gómez, J. M. G.

2018-05-01

During the last three decades the quest for chaos in nuclei has been quite intensive, both with theoretical calculations using nuclear models and with detailed analyses of experimental data. In this paper we outline the concept and characteristics of quantum chaos in two different approaches, the random matrix theory fluctuations and the time series fluctuations. Then we discuss the theoretical and experimental evidence of chaos in nuclei. Theoretical calculations, especially shell-model calculations, have shown a strongly chaotic behavior of bound states in regions of high level density. The analysis of experimental data has shown a strongly chaotic behavior of nuclear resonances just above the one-nucleon emission threshold. For bound states, combining experimental data of a large number of nuclei, a tendency towards chaotic motion is observed in spherical nuclei, while deformed nuclei exhibit a more regular behavior associated to the collective motion. On the other hand, it had never been possible to observe chaos in the experimental bound energy levels of any single nucleus. However, the complete experimental spectrum of the first 151 states up to excitation energies of 6.20 MeV in the 208Pb nucleus have been recently identified and the analysis of its spectral fluctuations clearly shows the existence of chaotic motion.

Electronic structure of CdSe-ZnS 2D nanoplatelets

NASA Astrophysics Data System (ADS)

Cruguel, Hervé; Livache, Clément; Martinez, Bertille; Pedetti, Silvia; Pierucci, Debora; Izquierdo, Eva; Dufour, Marion; Ithurria, Sandrine; Aubin, Hervé; Ouerghi, Abdelkarim; Lacaze, Emmanuelle; Silly, Mathieu G.; Dubertret, Benoit; Lhuillier, Emmanuel

2017-04-01

Among colloidal nanocrystals, 2D nanoplatelets (NPLs) made of cadmium chalcogenides have led to especially well controlled optical features. However, the growth of core shell heterostructures has so far been mostly focused on CdS shells, while more confined materials will be more promising to decouple the emitting quantum states of the core from their external environment. Using k.p simulation, we demonstrate that a ZnS shell reduces by a factor 10 the leakage of the wavefunction into the surrounding medium. Using X-ray photoemission (XPS), we confirm that the CdSe active layer is indeed unoxidized. Finally, we build an effective electronic spectrum for these CdSe/ZnS NPLs on an absolute energy scale which is a critical set of parameters for the future integration of this material into optoelectronic devices. We determine the work function (WF) to be 4.47 eV while the material is behaving as an n-type semiconductor.

Strain-Driven Stacking Faults in CdSe/CdS Core/Shell Nanorods.

PubMed

Demortière, Arnaud; Leonard, Donovan N; Petkov, Valeri; Chapman, Karena; Chattopadhyay, Soma; She, Chunxing; Cullen, David A; Shibata, Tomohiro; Pelton, Matthew; Shevchenko, Elena V

2018-04-19

Colloidal semiconductor nanocrystals are commonly grown with a shell of a second semiconductor material to obtain desired physical properties, such as increased photoluminescence quantum yield. However, the growth of a lattice-mismatched shell results in strain within the nanocrystal, and this strain has the potential to produce crystalline defects. Here, we study CdSe/CdS core/shell nanorods as a model system to investigate the influence of core size and shape on the formation of stacking faults in the nanocrystal. Using a combination of high-angle annular dark-field scanning transmission electron microscopy and pair-distribution-function analysis of synchrotron X-ray scattering, we show that growth of the CdS shell on smaller, spherical CdSe cores results in relatively small strain and few stacking faults. By contrast, growth of the shell on larger, prolate spheroidal cores leads to significant strain in the CdS lattice, resulting in a high density of stacking faults.

Emergent properties of nuclei from ab initio coupled-cluster calculations

NASA Astrophysics Data System (ADS)

Hagen, G.; Hjorth-Jensen, M.; Jansen, G. R.; Papenbrock, T.

2016-06-01

Emergent properties such as nuclear saturation and deformation, and the effects on shell structure due to the proximity of the scattering continuum and particle decay channels are fascinating phenomena in atomic nuclei. In recent years, ab initio approaches to nuclei have taken the first steps towards tackling the computational challenge of describing these phenomena from Hamiltonians with microscopic degrees of freedom. This endeavor is now possible due to ideas from effective field theories, novel optimization strategies for nuclear interactions, ab initio methods exhibiting a soft scaling with mass number, and ever-increasing computational power. This paper reviews some of the recent accomplishments. We also present new results. The recently optimized chiral interaction NNLO{}{{sat}} is shown to provide an accurate description of both charge radii and binding energies in selected light- and medium-mass nuclei up to 56Ni. We derive an efficient scheme for including continuum effects in coupled-cluster computations of nuclei based on chiral nucleon-nucleon and three-nucleon forces, and present new results for unbound states in the neutron-rich isotopes of oxygen and calcium. The coupling to the continuum impacts the energies of the {J}π =1/{2}-,3/{2}-,7/{2}-,3/{2}+ states in {}{17,23,25}O, and—contrary to naive shell-model expectations—the level ordering of the {J}π =3/{2}+,5/{2}+,9/{2}+ states in {}{53,55,61}Ca. ).

Ab initio many-body perturbation theory and no-core shell model

NASA Astrophysics Data System (ADS)

Hu, B. S.; Wu, Q.; Xu, F. R.

2017-10-01

In many-body perturbation theory (MBPT) we always introduce a parameter N shell to measure the maximal allowed major harmonic-oscillator (HO) shells for the single-particle basis, while the no-core shell model (NCSM) uses N maxℏΩ HO excitation truncation above the lowest HO configuration for the many-body basis. It is worth comparing the two different methods. Starting from “bare” and Okubo-Lee-Suzuki renormalized modern nucleon-nucleon interactions, NNLOopt and JISP16, we show that MBPT within Hartree-Fock bases is in reasonable agreement with NCSM within harmonic oscillator bases for 4He and 16O in “close” model space. In addition, we compare the results using “bare” force with the Okubo-Lee-Suzuki renormalized force. Supported by National Key Basic Research Program of China (2013CB834402), National Natural Science Foundation of China (11235001, 11320101004, 11575007) and the CUSTIPEN (China-U.S. Theory Institute for Physics with Exotic Nuclei) funded by the U.S. Department of Energy, Office of Science (DE-SC0009971)

Broadband absorption and enhanced photothermal conversion property of octopod-like Ag@Ag2S core@shell structures with gradually varying shell thickness.

PubMed

Jiang, Qian; Zeng, Wenxia; Zhang, Canying; Meng, Zhaoguo; Wu, Jiawei; Zhu, Qunzhi; Wu, Daxiong; Zhu, Haitao

2017-12-19

Photothermal conversion materials have promising applications in many fields and therefore they have attracted tremendous attention. However, the multi-functionalization of a single nanostructure to meet the requirements of multiple photothermal applications is still a challenge. The difficulty is that most nanostructures have specific absoprtion band and are not flexible to different demands. In the current work, we reported the synthesis and multi-band photothermal conversion of Ag@Ag 2 S core@shell structures with gradually varying shell thickness. We synthesized the core@shell structures through the sulfidation of Ag nanocubes by taking the advantage of their spatially different reactivity. The resulting core@shell structures show an octopod-like mopgorlogy with a Ag 2 S bulge sitting at each corner of the Ag nanocubes. The thickness of the Ag 2 S shell gradually increases from the central surface towards the corners of the structure. The synthesized core@shell structures show a broad band absorption spectrum from 300 to 1100 nm. Enhanced photothermal conversion effect is observed under the illuminations of 635, 808, and 1064 nm lasers. The results indicate that the octopod-like Ag@Ag 2 S core@shell structures have characteristics of multi-band photothermal conversion. The current work might provide a guidance for the design and synthesis of multifunctional photothermal conversion materials.

Connections between the dynamical symmetries in the microscopic shell model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Georgieva, A. I., E-mail: anageorg@issp.bas.bg; Drumev, K. P.

2016-03-25

The dynamical symmetries of the microscopic shell model appear as the limiting cases of a symmetry adapted Pairing-Plus-Quadrupole Model /PQM/, with a Hamiltonian containing isoscalar and isovector pairing and quadrupole interactions. We establish a correspondence between each of the three types of pairing bases and Elliott’s SU(3) basis, that describes collective rotation of nuclear systems with quadrupole deformation. It is derived from their complementarity to the same LS coupling chain of the shell model number conserving algebra. The probability distribution of the S U(3) basis states within the pairing eigenstates is also obtained through a numerical diagonalization of the PQMmore » Hamiltonian in each limit. We introduce control parameters, which define the phase diagram of the model and determine the role of each term of the Hamiltonian in the correct reproduction of the experimental data for the considered nuclei.« less

Precision measurement of the mass difference between light nuclei and anti-nuclei

NASA Astrophysics Data System (ADS)

Alice Collaboration; Adam, J.; Adamová, D.; Aggarwal, M. M.; Aglieri Rinella, G.; Agnello, M.; Agrawal, N.; Ahammed, Z.; Ahmed, I.; Ahn, S. U.; Aimo, I.; Aiola, S.; Ajaz, M.; Akindinov, A.; Alam, S. N.; Aleksandrov, D.; Alessandro, B.; Alexandre, D.; Alfaro Molina, R.; Alici, A.; Alkin, A.; Alme, J.; Alt, T.; Altinpinar, S.; Altsybeev, I.; Alves Garcia Prado, C.; Andrei, C.; Andronic, A.; Anguelov, V.; Anielski, J.; Antičić, T.; Antinori, F.; Antonioli, P.; Aphecetche, L.; Appelshäuser, H.; Arcelli, S.; Armesto, N.; Arnaldi, R.; Aronsson, T.; Arsene, I. C.; Arslandok, M.; Augustinus, A.; Averbeck, R.; Azmi, M. D.; Bach, M.; Badalà, A.; Baek, Y. W.; Bagnasco, S.; Bailhache, R.; Bala, R.; Baldisseri, A.; Ball, M.; Baltasar Dos Santos Pedrosa, F.; Baral, R. C.; Barbano, A. M.; Barbera, R.; Barile, F.; Barnaföldi, G. G.; Barnby, L. S.; Barret, V.; Bartalini, P.; Bartke, J.; Bartsch, E.; Basile, M.; Bastid, N.; Basu, S.; Bathen, B.; Batigne, G.; Batista Camejo, A.; Batyunya, B.; Batzing, P. C.; Bearden, I. G.; Beck, H.; Bedda, C.; Behera, N. K.; Belikov, I.; Bellini, F.; Bello Martinez, H.; Bellwied, R.; Belmont, R.; Belmont-Moreno, E.; Belyaev, V.; Bencedi, G.; Beole, S.; Berceanu, I.; Bercuci, A.; Berdnikov, Y.; Berenyi, D.; Bertens, R. A.; Berzano, D.; Betev, L.; Bhasin, A.; Bhat, I. R.; Bhati, A. K.; Bhattacharjee, B.; Bhom, J.; Bianchi, L.; Bianchi, N.; Bianchin, C.; Bielčík, J.; Bielčíková, J.; Bilandzic, A.; Biswas, S.; Bjelogrlic, S.; Blanco, F.; Blau, D.; Blume, C.; Bock, F.; Bogdanov, A.; Bøggild, H.; Boldizsár, L.; Bombara, M.; Book, J.; Borel, H.; Borissov, A.; Borri, M.; Bossú, F.; Botje, M.; Botta, E.; Böttger, S.; Braun-Munzinger, P.; Bregant, M.; Breitner, T.; Broker, T. A.; Browning, T. A.; Broz, M.; Brucken, E. J.; Bruna, E.; Bruno, G. E.; Budnikov, D.; Buesching, H.; Bufalino, S.; Buncic, P.; Busch, O.; Buthelezi, Z.; Buxton, J. T.; Caffarri, D.; Cai, X.; Caines, H.; Calero Diaz, L.; Caliva, A.; Calvo Villar, E.; Camerini, P.; Carena, F.; Carena, W.; Castillo Castellanos, J.; Castro, A. J.; Casula, E. A. R.; Cavicchioli, C.; Ceballos Sanchez, C.; Cepila, J.; Cerello, P.; Chang, B.; Chapeland, S.; Chartier, M.; Charvet, J. L.; Chattopadhyay, Subhasis; Chattopadhyay, Sukalyan; Chelnokov, V.; Cherney, M.; Cheshkov, C.; Cheynis, B.; Chibante Barroso, V.; Chinellato, D. D.; Chochula, P.; Choi, K.; Chojnacki, M.; Choudhury, S.; Christakoglou, P.; Christensen, C. H.; Christiansen, P.; Chujo, T.; Chung, S. U.; Cicalo, C.; Cifarelli, L.; Cindolo, F.; Cleymans, J.; Colamaria, F.; Colella, D.; Collu, A.; Colocci, M.; Conesa Balbastre, G.; Conesa Del Valle, Z.; Connors, M. E.; Contreras, J. G.; Cormier, T. M.; Corrales Morales, Y.; Cortés Maldonado, I.; Cortese, P.; Cosentino, M. R.; Costa, F.; Crochet, P.; Cruz Albino, R.; Cuautle, E.; Cunqueiro, L.; Dahms, T.; Dainese, A.; Danu, A.; Das, D.; Das, I.; Das, S.; Dash, A.; Dash, S.; de, S.; de Caro, A.; de Cataldo, G.; de Cuveland, J.; de Falco, A.; de Gruttola, D.; De Marco, N.; de Pasquale, S.; Deisting, A.; Deloff, A.; Dénes, E.; D'Erasmo, G.; di Bari, D.; di Mauro, A.; di Nezza, P.; Diaz Corchero, M. A.; Dietel, T.; Dillenseger, P.; Divià, R.; Djuvsland, Ø.; Dobrin, A.; Dobrowolski, T.; Domenicis Gimenez, D.; Dönigus, B.; Dordic, O.; Dubey, A. K.; Dubla, A.; Ducroux, L.; Dupieux, P.; Ehlers, R. J.; Elia, D.; Engel, H.; Erazmus, B.; Erhardt, F.; Eschweiler, D.; Espagnon, B.; Estienne, M.; Esumi, S.; Evans, D.; Evdokimov, S.; Eyyubova, G.; Fabbietti, L.; Fabris, D.; Faivre, J.; Fantoni, A.; Fasel, M.; Feldkamp, L.; Felea, D.; Feliciello, A.; Feofilov, G.; Ferencei, J.; Fernández Téllez, A.; Ferreiro, E. G.; Ferretti, A.; Festanti, A.; Figiel, J.; Figueredo, M. A. S.; Filchagin, S.; Finogeev, D.; Fionda, F. M.; Fiore, E. M.; Fleck, M. G.; Floris, M.; Foertsch, S.; Foka, P.; Fokin, S.; Fragiacomo, E.; Francescon, A.; Frankenfeld, U.; Fuchs, U.; Furget, C.; Furs, A.; Fusco Girard, M.; Gaardhøje, J. J.; Gagliardi, M.; Gago, A. M.; Gallio, M.; Gangadharan, D. R.; Ganoti, P.; Gao, C.; Garabatos, C.; Garcia-Solis, E.; Gargiulo, C.; Gasik, P.; Germain, M.; Gheata, A.; Gheata, M.; Ghosh, P.; Ghosh, S. K.; Gianotti, P.; Giubellino, P.; Giubilato, P.; Gladysz-Dziadus, E.; Glässel, P.; Goméz Coral, D. M.; Gomez Ramirez, A.; González-Zamora, P.; Gorbunov, S.; Görlich, L.; Gotovac, S.; Grabski, V.; Graczykowski, L. K.; Grelli, A.; Grigoras, A.; Grigoras, C.; Grigoriev, V.; Grigoryan, A.; Grigoryan, S.; Grinyov, B.; Grion, N.; Grosse-Oetringhaus, J. F.; Grossiord, J.-Y.; Grosso, R.; Guber, F.; Guernane, R.; Guerzoni, B.; Gulbrandsen, K.; Gulkanyan, H.; Gunji, T.; Gupta, A.; Gupta, R.; Haake, R.; Haaland, Ø.; Hadjidakis, C.; Haiduc, M.; Hamagaki, H.; Hamar, G.; Hanratty, L. D.; Hansen, A.; Harris, J. W.; Hartmann, H.; Harton, A.; Hatzifotiadou, D.; Hayashi, S.; Heckel, S. T.; Heide, M.; Helstrup, H.; Herghelegiu, A.; Herrera Corral, G.; Hess, B. A.; Hetland, K. F.; Hilden, T. E.; Hillemanns, H.; Hippolyte, B.; Hristov, P.; Huang, M.; Humanic, T. J.; Hussain, N.; Hussain, T.; Hutter, D.; Hwang, D. S.; Ilkaev, R.; Ilkiv, I.; Inaba, M.; Ionita, C.; Ippolitov, M.; Irfan, M.; Ivanov, M.; Ivanov, V.; Izucheev, V.; Jacobs, P. M.; Jahnke, C.; Jang, H. J.; Janik, M. A.; Jayarathna, P. H. S. Y.; Jena, C.; Jena, S.; Jimenez Bustamante, R. T.; Jones, P. G.; Jung, H.; Jusko, A.; Kalinak, P.; Kalweit, A.; Kamin, J.; Kang, J. H.; Kaplin, V.; Kar, S.; Karasu Uysal, A.; Karavichev, O.; Karavicheva, T.; Karpechev, E.; Kebschull, U.; Keidel, R.; Keijdener, D. L. D.; Keil, M.; Khan, K. H.; Khan, M. Mohisin; Khan, P.; Khan, S. A.; Khanzadeev, A.; Kharlov, Y.; Kileng, B.; Kim, B.; Kim, D. W.; Kim, D. J.; Kim, H.; Kim, J. S.; Kim, Mimae.; Kim, Minwoo; Kim, S.; Kim, T.; Kirsch, S.; Kisel, I.; Kiselev, S.; Kisiel, A.; Kiss, G.; Klay, J. L.; Klein, C.; Klein, J.; Klein-Bösing, C.; Kluge, A.; Knichel, M. L.; Knospe, A. G.; Kobayashi, T.; Kobdaj, C.; Kofarago, M.; Köhler, M. K.; Kollegger, T.; Kolojvari, A.; Kondratiev, V.; Kondratyeva, N.; Kondratyuk, E.; Konevskikh, A.; Kour, M.; Kouzinopoulos, C.; Kovalenko, V.; Kowalski, M.; Kox, S.; Koyithatta Meethaleveedu, G.; Kral, J.; Králik, I.; Kravčáková, A.; Krelina, M.; Kretz, M.; Krivda, M.; Krizek, F.; Kryshen, E.; Krzewicki, M.; Kubera, A. M.; Kučera, V.; Kucheriaev, Y.; Kugathasan, T.; Kuhn, C.; Kuijer, P. G.; Kulakov, I.; Kumar, A.; Kumar, J.; Kumar, L.; Kurashvili, P.; Kurepin, A.; Kurepin, A. B.; Kuryakin, A.; Kushpil, S.; Kweon, M. J.; Kwon, Y.; La Pointe, S. L.; La Rocca, P.; Lagana Fernandes, C.; Lakomov, I.; Langoy, R.; Lara, C.; Lardeux, A.; Lattuca, A.; Laudi, E.; Lea, R.; Leardini, L.; Lee, G. R.; Lee, S.; Legrand, I.; Lehnert, J.; Lemmon, R. C.; Lenti, V.; Leogrande, E.; León Monzón, I.; Leoncino, M.; Lévai, P.; Li, S.; Li, X.; Lien, J.; Lietava, R.; Lindal, S.; Lindenstruth, V.; Lippmann, C.; Lisa, M. A.; Ljunggren, H. M.; Lodato, D. F.; Loenne, P. I.; Loggins, V. R.; Loginov, V.; Loizides, C.; Lopez, X.; López Torres, E.; Lowe, A.; Lu, X.-G.; Luettig, P.; Lunardon, M.; Luparello, G.; Maevskaya, A.; Mager, M.; Mahajan, S.; Mahmood, S. M.; Maire, A.; Majka, R. D.; Malaev, M.; Maldonado Cervantes, I.; Malinina, L.; Mal'Kevich, D.; Malzacher, P.; Mamonov, A.; Manceau, L.; Manko, V.; Manso, F.; Manzari, V.; Marchisone, M.; Mareš, J.; Margagliotti, G. V.; Margotti, A.; Margutti, J.; Marín, A.; Markert, C.; Marquard, M.; Martashvili, I.; Martin, N. A.; Martin Blanco, J.; Martinengo, P.; Martínez, M. I.; Martínez García, G.; Martinez Pedreira, M.; Martynov, Y.; Mas, A.; Masciocchi, S.; Masera, M.; Masoni, A.; Massacrier, L.; Mastroserio, A.; Matyja, A.; Mayer, C.; Mazer, J.; Mazzoni, M. A.; McDonald, D.; Meddi, F.; Menchaca-Rocha, A.; Meninno, E.; Mercado Pérez, J.; Meres, M.; Miake, Y.; Mieskolainen, M. M.; Mikhaylov, K.; Milano, L.; Milosevic, J.; Minervini, L. M.; Mischke, A.; Mishra, A. N.; Miśkowiec, D.; Mitra, J.; Mitu, C. M.; Mohammadi, N.; Mohanty, B.; Molnar, L.; Montaño Zetina, L.; Montes, E.; Morando, M.; Moreira de Godoy, D. A.; Moreno, L. A. P.; Moretto, S.; Morreale, A.; Morsch, A.; Muccifora, V.; Mudnic, E.; Mühlheim, D.; Muhuri, S.; Mukherjee, M.; Müller, H.; Mulligan, J. D.; Munhoz, M. G.; Murray, S.; Musa, L.; Musinsky, J.; Nandi, B. K.; Nania, R.; Nappi, E.; Naru, M. U.; Nattrass, C.; Nayak, K.; Nayak, T. K.; Nazarenko, S.; Nedosekin, A.; Nellen, L.; Ng, F.; Nicassio, M.; Niculescu, M.; Niedziela, J.; Nielsen, B. S.; Nikolaev, S.; Nikulin, S.; Nikulin, V.; Noferini, F.; Nomokonov, P.; Nooren, G.; Norman, J.; Nyanin, A.; Nystrand, J.; Oeschler, H.; Oh, S.; Oh, S. K.; Ohlson, A.; Okatan, A.; Okubo, T.; Olah, L.; Oleniacz, J.; Oliveira da Silva, A. C.; Oliver, M. H.; Onderwaater, J.; Oppedisano, C.; Ortiz Velasquez, A.; Oskarsson, A.; Otwinowski, J.; Oyama, K.; Ozdemir, M.; Pachmayer, Y.; Pagano, P.; Paić, G.; Pajares, C.; Pal, S. K.; Pan, J.; Pandey, A. K.; Pant, D.; Papikyan, V.; Pappalardo, G. S.; Pareek, P.; Park, W. J.; Parmar, S.; Passfeld, A.; Paticchio, V.; Paul, B.; Pawlak, T.; Peitzmann, T.; Pereira da Costa, H.; Pereira de Oliveira Filho, E.; Peresunko, D.; Pérez Lara, C. E.; Peskov, V.; Pestov, Y.; Petráček, V.; Petrov, V.; Petrovici, M.; Petta, C.; Piano, S.; Pikna, M.; Pillot, P.; Pinazza, O.; Pinsky, L.; Piyarathna, D. B.; Płoskoń, M.; Planinic, M.; Pluta, J.; Pochybova, S.; Podesta-Lerma, P. L. M.; Poghosyan, M. G.; Polichtchouk, B.; Poljak, N.; Poonsawat, W.; Pop, A.; Porteboeuf-Houssais, S.; Porter, J.; Pospisil, J.; Prasad, S. K.; Preghenella, R.; Prino, F.; Pruneau, C. A.; Pshenichnov, I.; Puccio, M.; Puddu, G.; Pujahari, P.; Punin, V.; Putschke, J.; Qvigstad, H.; Rachevski, A.; Raha, S.; Rajput, S.; Rak, J.; Rakotozafindrabe, A.; Ramello, L.; Raniwala, R.; Raniwala, S.; Räsänen, S. S.; Rascanu, B. T.; Rathee, D.; Razazi, V.; Read, K. F.; Real, J. S.; Redlich, K.; Reed, R. J.; Rehman, A.; Reichelt, P.; Reicher, M.; Reidt, F.; Ren, X.; Renfordt, R.; Reolon, A. R.; Reshetin, A.; Rettig, F.; Revol, J.-P.; Reygers, K.; Riabov, V.; Ricci, R. A.; Richert, T.; Richter, M.; Riedler, P.; Riegler, W.; Riggi, F.; Ristea, C.; Rivetti, A.; Rocco, E.; Rodríguez Cahuantzi, M.; Rodriguez Manso, A.; Røed, K.; Rogochaya, E.; Rohr, D.; Röhrich, D.; Romita, R.; Ronchetti, F.; Ronflette, L.; Rosnet, P.; Rossi, A.; Roukoutakis, F.; Roy, A.; Roy, C.; Roy, P.; Rubio Montero, A. J.; Rui, R.; Russo, R.; Ryabinkin, E.; Ryabov, Y.; Rybicki, A.; Sadovsky, S.; Šafařík, K.; Sahlmuller, B.; Sahoo, P.; Sahoo, R.; Sahoo, S.; Sahu, P. K.; Saini, J.; Sakai, S.; Saleh, M. A.; Salgado, C. A.; Salzwedel, J.; Sambyal, S.; Samsonov, V.; Sanchez Castro, X.; Šándor, L.; Sandoval, A.; Sano, M.; Santagati, G.; Sarkar, D.; Scapparone, E.; Scarlassara, F.; Scharenberg, R. P.; Schiaua, C.; Schicker, R.; Schmidt, C.; Schmidt, H. R.; Schuchmann, S.; Schukraft, J.; Schulc, M.; Schuster, T.; Schutz, Y.; Schwarz, K.; Schweda, K.; Scioli, G.; Scomparin, E.; Scott, R.; Seeder, K. S.; Seger, J. E.; Sekiguchi, Y.; Selyuzhenkov, I.; Senosi, K.; Seo, J.; Serradilla, E.; Sevcenco, A.; Shabanov, A.; Shabetai, A.; Shadura, O.; Shahoyan, R.; Shangaraev, A.; Sharma, A.; Sharma, M.; Sharma, N.; Shigaki, K.; Shtejer, K.; Sibiriak, Y.; Siddhanta, S.; Sielewicz, K. M.; Siemiarczuk, T.; Silvermyr, D.; Silvestre, C.; Simatovic, G.; Simonetti, G.; Singaraju, R.; Singh, R.; Singha, S.; Singhal, V.; Sinha, B. C.; Sinha, T.; Sitar, B.; Sitta, M.; Skaali, T. B.; Slupecki, M.; Smirnov, N.; Snellings, R. J. M.; Snellman, T. W.; Søgaard, C.; Soltz, R.; Song, J.; Song, M.; Song, Z.; Soramel, F.; Sorensen, S.; Spacek, M.; Spiriti, E.; Sputowska, I.; Spyropoulou-Stassinaki, M.; Srivastava, B. K.; Stachel, J.; Stan, I.; Stefanek, G.; Steinpreis, M.; Stenlund, E.; Steyn, G.; Stiller, J. H.; Stocco, D.; Strmen, P.; Suaide, A. A. P.; Sugitate, T.; Suire, C.; Suleymanov, M.; Sultanov, R.; Šumbera, M.; Symons, T. J. M.; Szabo, A.; Szanto de Toledo, A.; Szarka, I.; Szczepankiewicz, A.; Szymanski, M.; Takahashi, J.; Tanaka, N.; Tangaro, M. A.; Tapia Takaki, J. D.; Tarantola Peloni, A.; Tariq, M.; Tarzila, M. G.; Tauro, A.; Tejeda Muñoz, G.; Telesca, A.; Terasaki, K.; Terrevoli, C.; Teyssier, B.; Thäder, J.; Thomas, D.; Tieulent, R.; Timmins, A. R.; Toia, A.; Trogolo, S.; Trubnikov, V.; Trzaska, W. H.; Tsuji, T.; Tumkin, A.; Turrisi, R.; Tveter, T. S.; Ullaland, K.; Uras, A.; Usai, G. L.; Utrobicic, A.; Vajzer, M.; Vala, M.; Valencia Palomo, L.; Vallero, S.; van der Maarel, J.; van Hoorne, J. W.; van Leeuwen, M.; Vanat, T.; Vande Vyvre, P.; Varga, D.; Vargas, A.; Vargyas, M.; Varma, R.; Vasileiou, M.; Vasiliev, A.; Vauthier, A.; Vechernin, V.; Veen, A. M.; Veldhoen, M.; Velure, A.; Venaruzzo, M.; Vercellin, E.; Vergara Limón, S.; Vernet, R.; Verweij, M.; Vickovic, L.; Viesti, G.; Viinikainen, J.; Vilakazi, Z.; Villalobos Baillie, O.; Villatoro Tello, A.; Vinogradov, A.; Vinogradov, L.; Vinogradov, Y.; Virgili, T.; Vislavicius, V.; Viyogi, Y. P.; Vodopyanov, A.; Völkl, M. A.; Voloshin, K.; Voloshin, S. A.; Volpe, G.; von Haller, B.; Vorobyev, I.; Vranic, D.; Vrláková, J.; Vulpescu, B.; Vyushin, A.; Wagner, B.; Wagner, J.; Wang, H.; Wang, M.; Wang, Y.; Watanabe, D.; Weber, M.; Weber, S. G.; Wessels, J. P.; Westerhoff, U.; Wiechula, J.; Wikne, J.; Wilde, M.; Wilk, G.; Wilkinson, J.; Williams, M. C. S.; Windelband, B.; Winn, M.; Yaldo, C. G.; Yamaguchi, Y.; Yang, H.; Yang, P.; Yano, S.; Yasnopolskiy, S.; Yin, Z.; Yokoyama, H.; Yoo, I.-K.; Yurchenko, V.; Yushmanov, I.; Zaborowska, A.; Zaccolo, V.; Zaman, A.; Zampolli, C.; Zanoli, H. J. C.; Zaporozhets, S.; Zarochentsev, A.; Závada, P.; Zaviyalov, N.; Zbroszczyk, H.; Zgura, I. S.; Zhalov, M.; Zhang, H.; Zhang, X.; Zhang, Y.; Zhao, C.; Zhigareva, N.; Zhou, D.; Zhou, Y.; Zhou, Z.; Zhu, H.; Zhu, J.; Zhu, X.; Zichichi, A.; Zimmermann, A.; Zimmermann, M. B.; Zinovjev, G.; Zyzak, M.

2015-10-01

The measurement of the mass differences for systems bound by the strong force has reached a very high precision with protons and anti-protons. The extension of such measurement from (anti-)baryons to (anti-)nuclei allows one to probe any difference in the interactions between nucleons and anti-nucleons encoded in the (anti-)nuclei masses. This force is a remnant of the underlying strong interaction among quarks and gluons and can be described by effective theories, but cannot yet be directly derived from quantum chromodynamics. Here we report a measurement of the difference between the ratios of the mass and charge of deuterons (d) and anti-deuterons (), and 3He and nuclei carried out with the ALICE (A Large Ion Collider Experiment) detector in Pb-Pb collisions at a centre-of-mass energy per nucleon pair of 2.76 TeV. Our direct measurement of the mass-over-charge differences confirms CPT invariance to an unprecedented precision in the sector of light nuclei. This fundamental symmetry of nature, which exchanges particles with anti-particles, implies that all physics laws are the same under the simultaneous reversal of charge(s) (charge conjugation C), reflection of spatial coordinates (parity transformation P) and time inversion (T).

Study of hot thermally fissile nuclei using relativistic mean field theory

NASA Astrophysics Data System (ADS)

Quddus, Abdul; Naik, K. C.; Patra, S. K.

2018-07-01

We have studied the properties of hot 234,236U and 240Pu nuclei in the framework of relativistic mean field formalism. The recently developed FSUGarnet and IOPB-I parameter sets are implemented for the first time to deform nuclei at finite temperature. The results are compared with the well known NL3 set. The said isotopes are structurally important because of the thermally fissile nature of 233,235U and 239Pu as these nuclei (234,236U and 240Pu) are formed after the absorption of a thermal neutron, which undergoes fission. Here, we have evaluated the nuclear properties, such as shell correction energy, neutron-skin thickness, quadrupole and hexadecapole deformation parameters and asymmetry energy coefficient for these nuclei as a function of temperature.

Ultrafast light matter interaction in CdSe/ZnS core-shell quantum dots

NASA Astrophysics Data System (ADS)

Yadav, Rajesh Kumar; Sharma, Rituraj; Mondal, Anirban; Adarsh, K. V.

2018-04-01

Core-shell quantum dot are imperative for carrier (electron and holes) confinement in core/shell, which provides a stage to explore the linear and nonlinear optical phenomena at the nanoscalelimit. Here we present a comprehensive study of ultrafast excitation dynamics and nonlinear optical absorption of CdSe/ZnS core shell quantum dot with the help of ultrafast spectroscopy. Pump-probe and time-resolved measurements revealed the drop of trapping at CdSe surface due to the presence of the ZnS shell, which makes more efficient photoluminescence. We have carried out femtosecond transient absorption studies of the CdSe/ZnS core-shell quantum dot by irradiation with 400 nm laser light, monitoring the transients in the visible region. The optical nonlinearity of the core-shell quantum dot studied by using the Z-scan technique with 120 fs pulses at the wavelengths of 800 nm. The value of two photon absorption coefficients (β) of core-shell QDs extracted as80cm/GW, and it shows excellent benchmark for the optical limiting onset of 2.5GW/cm2 with the low limiting differential transmittance of 0.10, that is an order of magnitude better than graphene based materials.

Shell Layer Thickness-Dependent Photocatalytic Activity of Sputtering Synthesized Hexagonally Structured ZnO-ZnS Composite Nanorods

PubMed Central

Liang, Yuan-Chang; Lo, Ya-Ru; Wang, Chein-Chung; Xu, Nian-Cih

2018-01-01

ZnO-ZnS core-shell nanorods are synthesized by combining the hydrothermal method and vacuum sputtering. The core-shell nanorods with variable ZnS shell thickness (7–46 nm) are synthesized by varying ZnS sputtering duration. Structural analyses demonstrated that the as-grown ZnS shell layers are well crystallized with preferring growth direction of ZnS (002). The sputtering-assisted synthesized ZnO-ZnS core-shell nanorods are in a wurtzite structure. Moreover, photoluminance spectral analysis indicated that the introduction of a ZnS shell layer improved the photoexcited electron and hole separation efficiency of the ZnO nanorods. A strong correlation between effective charge separation and the shell thickness aids the photocatalytic behavior of the nanorods and improves their photoresponsive nature. The results of comparative degradation efficiency toward methylene blue showed that the ZnO-ZnS nanorods with the shell thickness of approximately 17 nm have the highest photocatalytic performance than the ZnO-ZnS nanorods with other shell layer thicknesses. The highly reusable catalytic efficiency and superior photocatalytic performance of the ZnO-ZnS nanorods with 17 nm-thick ZnS shell layer supports their potential for environmental applications. PMID:29316671

Atomistic tight-binding theory of excitonic splitting energies in CdX(X = Se, S and Te)/ZnS core/shell nanocrystals

NASA Astrophysics Data System (ADS)

Sukkabot, Worasak; Pinsook, Udomsilp

2017-01-01

Using the atomistic tight-binding theory (TB) and a configuration interaction description (CI), we numerically compute the excitonic splitting of CdX(X = Se, S and Te)/ZnS core/shell nanocrystals with the objective to explain how types of the core materials and growth shell thickness can provide the detailed manipulation of the dark-dark (DD), dark-bright (DB) and bright-bright (BB) excitonic splitting, beneficial for the active application of quantum information. To analyze the splitting of the excitonic states, the optical band gaps, ground-state wave function overlaps and atomistic electron-hole interactions tend to be numerically demonstrated. Based on the atomistic computations, the single-particle and excitonic gaps are mainly reduced with the increasing ZnS shell thickness owing to the quantum confinement. In the range of the higher to lower energies, the order of the single-particle gaps is CdSe/ZnS, CdS/ZnS and CdTe/ZnS core/shell nanocrystals, while one of the excitonic gaps is CdS/ZnS, CdSe/ZnS and CdTe/ZnS core/shell nanocrystals because of the atomistic electron-hole interaction. The strongest electron-hole interactions are mainly observed in CdSe/ZnS core/shell nanocrystals. In addition, the computational results underline that the energies of the dark-dark (DD), dark-bright (DB) and bright-bright (BB) excitonic splitting are generally reduced with the increasing ZnS growth shell thickness as described by the trend of the electron-hole exchange interaction. The high-to-low splitting of the excitonic states is demonstrated in CdSe/ZnS, CdTe/ZnS and CdS/ZnS core/shell nanocrystals because of the fashion in the electron-hole exchange interaction and overlaps of the electron-hole wave functions. As the resulting calculations, it is expected that CdS/ZnS core/shell nanocrystals are the best candidates to be the source of entangled photons. Finally, the comprehensive information on the excitonic splitting can enable the use of suitable core/shell

Informing neutron capture nucleosynthesis on short-lived nuclei with (d,p) reactions

NASA Astrophysics Data System (ADS)

Cizewski, Jolie A.; Ratkiewicz, Andrew; Escher, Jutta E.; Lepailleur, Alexandre; Pain, Steven D.; Potel, Gregory

2018-01-01

Neutron capture on unstable nuclei is important in understanding abundances in r-process nucleosynthesis. Previously, the non-elastic breakup of the deuteron in the (d,p) reaction has been shown to provide a neutron that can be captured by the nucleus and the gamma-ray decay of the subsequent compound nucleus can be modelled to predict the gamma-ray decay of the compound nucleus in the (n,γ) reaction. Preliminary results from the 95Mo(d,pγ) reaction in normal kinematics support the (d,pγ) reaction as a valid surrogate for neutron capture. The techniques to measure the (d,pγ) reaction in inverse kinematics have been developed.

Hierarchical MoO3/SnS2 core-shell nanowires with enhanced electrochemical performance for lithium-ion batteries.

PubMed

Hu, Chenli; Shu, Haibo; Shen, Zihong; Zhao, Tianfeng; Liang, Pei; Chen, Xiaoshuang

2018-06-27

Two-dimensional (2D) tin disulfide (SnS2) is a promising anode material for lithium-ion batteries (LIBs) because of its high theoretical capacity. The main challenges associated with the SnS2 electrodes are the poor cycling stability and low rate capability due to structural degradation in the discharge/charge process. Here, a facile two-step synthesis method is developed to fabricate hierarchical MoO3/SnS2 core-shell nanowires, where ultrathin SnS2 nanosheets are vertically anchored on MoO3 nanobelts to induce a heterointerface. Benefiting from the unique structural and compositional characteristics, the hierarchical MoO3/SnS2 core-shell nanowires exhibit excellent electrochemical performance and deliver a high reversible capacity of 504 mA h g-1 after 100 stable cycles at a current density of 100 mA g-1, which is far superior to the MoO3 and SnS2 electrodes. An analysis of lithiation dynamics based on ab initio molecular dynamics simulations demonstrates that the formation of a hierarchical MoO3/SnS2 core-shell heterostructure can effectively suppress the rapid dissociation of shell-layer SnS2 nanosheets via the interfacial coupling effect and the central MoO3 backbone can trap and support the polysulfide in the discharge/charge process. The results are responsible for the high storage capacity and rate capability of MoO3/SnS2 electrode materials. This work provides a novel design strategy for constructing high-performance electrodes for LIBs.

Efficient photocatalytic degradation of malachite green dye under visible irradiation by water soluble ZnS:Mn/ZnS core/shell nanoparticles

NASA Astrophysics Data System (ADS)

Khaparde, Rohini A.; Acharya, Smita A.

2018-05-01

ZnS:Mn/ ZnS core/shell nanoparticles was prepared by two step synthesis method. In first step, oleic acid - coated Mn doped ZnS core nanoparticles were prepared which were charged through ligand exchange. Shell of ZnS NPs was finally deposited upon the surface of charged Mn doped ZnS core. Scanning electron microscopy (SEM) image exhibit morphological confirmation of ZnS:Mn/ZnS core/shell. As Nano ZnS are the most suitable candidates for photocatalyst that extensively involved in degradation and complete mineralization of various toxic organic pollutants owing to its high efficiency, strong oxidizing power, non-toxicity, high photochemical and biological stability, corrosive resistance and low cost. Photodegradation of malachite green is systematically investigated by adding different molar proportional of ZnS:Mn/ZnS core/shell in the dye. The rate of de-coloration of dye is detected by UV-VIS absorption spectroscopy. Efficient detoriation in the colour of dye is attributed to the core /shell morphology of the particles.

Geiger-Nuttall Law for Nuclei in Strong Electromagnetic Fields.

PubMed

Delion, D S; Ghinescu, S A

2017-11-17

We investigate the influence of a strong laser electromagnetic field on the α-decay rate by using the Hennenberger frame of reference. We introduce an adimensional parameter D=S_{0}/R_{0}, where R_{0} is the geometrical nuclear radius and S_{0}∼sqrt[I]/ω^{2} is a length parameter depending on the laser intensity I and frequency ω. We show that the barrier penetrability has a strong increase for intensities corresponding to D>D_{crit}=1, due to the fact that the resulting Coulomb potential becomes strongly anisotropic even for spherical nuclei. As a consequence, the contribution of the monopole term increases the barrier penetrability by 2 orders of magnitude, while the total contribution has an effect of 6 orders of magnitude at D∼3D_{crit}. In the case of deformed nuclei, the electromagnetic field increases the penetrability by an additional order of magnitude for a quadrupole deformation β_{2}∼0.3. The influence of the electromagnetic field can be expressed in terms of a shifted Geiger-Nuttal law by a term depending on S_{0} and deformation.

Impact of physical confinement on nuclei geometry and cell division dynamics in 3D spheroids.

PubMed

Desmaison, Annaïck; Guillaume, Ludivine; Triclin, Sarah; Weiss, Pierre; Ducommun, Bernard; Lobjois, Valérie

2018-06-08

Multicellular tumour spheroids are used as a culture model to reproduce the 3D architecture, proliferation gradient and cell interactions of a tumour micro-domain. However, their 3D characterization at the cell scale remains challenging due to size and cell density issues. In this study, we developed a methodology based on 3D light sheet fluorescence microscopy (LSFM) image analysis and convex hull calculation that allows characterizing the 3D shape and orientation of cell nuclei relative to the spheroid surface. By using this technique and optically cleared spheroids, we found that in freely growing spheroids, nuclei display an elongated shape and are preferentially oriented parallel to the spheroid surface. This geometry is lost when spheroids are grown in conditions of physical confinement. Live 3D LSFM analysis of cell division revealed that confined growth also altered the preferential cell division axis orientation parallel to the spheroid surface and induced prometaphase delay. These results provide key information and parameters that help understanding the impact of physical confinement on cell proliferation within tumour micro-domains.

Emergent properties of nuclei from ab initio coupled-cluster calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hagen, G.; Hjorth-Jensen, M.; Jansen, G. R.

Emergent properties such as nuclear saturation and deformation, and the effects on shell structure due to the proximity of the scattering continuum and particle decay channels are fascinating phenomena in atomic nuclei. In recent years, ab initio approaches to nuclei have taken the first steps towards tackling the computational challenge of describing these phenomena from Hamiltonians with microscopic degrees of freedom. Our endeavor is now possible due to ideas from effective field theories, novel optimization strategies for nuclear interactions, ab initio methods exhibiting a soft scaling with mass number, and ever-increasing computational power. We review some of the recent accomplishments. We also present new results. The recently optimized chiral interaction NNLOmore » $${}_{{\\rm{sat}}}$$ is shown to provide an accurate description of both charge radii and binding energies in selected light- and medium-mass nuclei up to 56Ni. We derive an efficient scheme for including continuum effects in coupled-cluster computations of nuclei based on chiral nucleon–nucleon and three-nucleon forces, and present new results for unbound states in the neutron-rich isotopes of oxygen and calcium. Finally, the coupling to the continuum impacts the energies of the $${J}^{\\pi }=1/{2}^{-},3/{2}^{-},7/{2}^{-},3/{2}^{+}$$ states in $${}^{\\mathrm{17,23,25}}$$O, and—contrary to naive shell-model expectations—the level ordering of the $${J}^{\\pi }=3/{2}^{+},5/{2}^{+},9/{2}^{+}$$ states in $${}^{\\mathrm{53,55,61}}$$Ca.« less

Emergent properties of nuclei from ab initio coupled-cluster calculations

DOE PAGES

Hagen, G.; Hjorth-Jensen, M.; Jansen, G. R.; ...

2016-05-17

Emergent properties such as nuclear saturation and deformation, and the effects on shell structure due to the proximity of the scattering continuum and particle decay channels are fascinating phenomena in atomic nuclei. In recent years, ab initio approaches to nuclei have taken the first steps towards tackling the computational challenge of describing these phenomena from Hamiltonians with microscopic degrees of freedom. Our endeavor is now possible due to ideas from effective field theories, novel optimization strategies for nuclear interactions, ab initio methods exhibiting a soft scaling with mass number, and ever-increasing computational power. We review some of the recent accomplishments. We also present new results. The recently optimized chiral interaction NNLOmore » $${}_{{\\rm{sat}}}$$ is shown to provide an accurate description of both charge radii and binding energies in selected light- and medium-mass nuclei up to 56Ni. We derive an efficient scheme for including continuum effects in coupled-cluster computations of nuclei based on chiral nucleon–nucleon and three-nucleon forces, and present new results for unbound states in the neutron-rich isotopes of oxygen and calcium. Finally, the coupling to the continuum impacts the energies of the $${J}^{\\pi }=1/{2}^{-},3/{2}^{-},7/{2}^{-},3/{2}^{+}$$ states in $${}^{\\mathrm{17,23,25}}$$O, and—contrary to naive shell-model expectations—the level ordering of the $${J}^{\\pi }=3/{2}^{+},5/{2}^{+},9/{2}^{+}$$ states in $${}^{\\mathrm{53,55,61}}$$Ca.« less

CdSe/AsS core-shell quantum dots: preparation and two-photon fluorescence.

PubMed

Wang, Junzhong; Lin, Ming; Yan, Yongli; Wang, Zhe; Ho, Paul C; Loh, Kian Ping

2009-08-19

Arsenic(II) sulfide (AsS)-coated CdSe core-shell nanocrystals can be prepared by a cluster-complex deposition approach under mild conditions. At 60 degrees C, growth of an AsS shell onto a CdSe nanocrystal can be realized through the crystallization of a cluster complex of AsS/butylamine in a mixed solvent of isopropanol/chloroform. The new, type I core-shell nanocrystal exhibits markedly enhanced one-photon fluorescence as well two-photon upconversion fluorescence. The nanocrystals can be used for infrared-excited upconversion cellular labeling.

Architected Lattices with High Stiffness and Toughness via Multicore-Shell 3D Printing.

PubMed

Mueller, Jochen; Raney, Jordan R; Shea, Kristina; Lewis, Jennifer A

2018-03-01

The ability to create architected materials that possess both high stiffness and toughness remains an elusive goal, since these properties are often mutually exclusive. Natural materials, such as bone, overcome such limitations by combining different toughening mechanisms across multiple length scales. Here, a new method for creating architected lattices composed of core-shell struts that are both stiff and tough is reported. Specifically, these lattices contain orthotropic struts with flexible epoxy core-brittle epoxy shell motifs in the absence and presence of an elastomeric silicone interfacial layer, which are fabricated by a multicore-shell, 3D printing technique. It is found that architected lattices produced with a flexible core-elastomeric interface-brittle shell motif exhibit both high stiffness and toughness. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

D1 dopamine receptor is involved in shell formation in larvae of Pacific oyster Crassostrea gigas.

PubMed

Liu, Zhaoqun; Wang, Lingling; Yan, Yunchen; Zheng, Yan; Ge, Wenjing; Li, Meijia; Wang, Weilin; Song, Xiaorui; Song, Linsheng

2018-07-01

Dopamine (DA), a significant member of catecholamines, is reported to induce biomineralization of calcium carbonate vaterite microspheres via dopamine receptor (DR) in bivalves, implying the modulation of dopaminergic system on shell formation during larval development. In this research, a homologue of D1 type DR (CgD1DR-1) was identified from oyster Crassostrea gigas, whose full length cDNA was 1197 bp. It was widely expressed in various tissues of C. gigas, with the significantly higher levels in hepatopancreas, mantle, muscle and gill. During developmental stages, the mRNA transcripts of CgD1DR-1 in D-shape larvae were obviously higher (p < 0.05) than those in trochophore and umbo larvae, and CO 2 exposure could inhibit the synthesis of DA and mRNA expression of CgD1DR-1. After cell transfection and DA treatment, intracellular cAMP in cells with the expression of CgD1DR-1 increased significantly (p < 0.05). Furthermore, the incubation with SCH 23390 for the blockage of CgD1DR-1 significantly restrained the expressions of six shell formation-related genes including CgTyrosinase-1, CgTyrosinase-3, CgChitinaseLP, CgAMC, CgBMP and CgBMPR in trochophore and D-shape larvae. These results jointly suggested that DA together with its receptor CgD1DR-1 might be involved in shell formation during oyster larval development from trochophore to D-shape larvae, and CO 2 -induced ocean acidification (OA) might influence marine bivalves by inhibiting the DA-D1DR pathway to prohibit their shell formation. Copyright © 2018 Elsevier Ltd. All rights reserved.

Dielectronic recombination of the 4p and 4d open sub-shell tungsten ions

NASA Astrophysics Data System (ADS)

Li, M. J.; Fu, Y. B.; Zhang, G. D.; Zhang, Y. Z.; Dong, C. Z.; Koike, F.

2014-04-01

Dielectronic recombination rate coefficients are given theoretically for several highly charged tungsten ions. As 4p open sub-shell ions, Ga-, Ge-, As-, Br-, Kr-like ions are considered. Rb-like ion is further considered as a 4d open sub-shell ion. Theoretical calculations are carried out using a relativistic atomic code FAC. The effect of configuration interaction is taking into account. Inner-shell electron excitations play a significant role for the dielectronic recombination process. Simple analytical formulae are given for the total rate coefficients by fitting to the presently obtained numerical results.

Analysis of Composite Skin-Stiffener Debond Specimens Using a Shell/3D Modeling Technique and Submodeling

NASA Technical Reports Server (NTRS)

OBrien, T. Kevin (Technical Monitor); Krueger, Ronald; Minguet, Pierre J.

2004-01-01

The application of a shell/3D modeling technique for the simulation of skin/stringer debond in a specimen subjected to tension and three-point bending was studied. The global structure was modeled with shell elements. A local three-dimensional model, extending to about three specimen thicknesses on either side of the delamination front was used to model the details of the damaged section. Computed total strain energy release rates and mixed-mode ratios obtained from shell/3D simulations were in good agreement with results obtained from full solid models. The good correlation of the results demonstrated the effectiveness of the shell/3D modeling technique for the investigation of skin/stiffener separation due to delamination in the adherents. In addition, the application of the submodeling technique for the simulation of skin/stringer debond was also studied. Global models made of shell elements and solid elements were studied. Solid elements were used for local submodels, which extended between three and six specimen thicknesses on either side of the delamination front to model the details of the damaged section. Computed total strain energy release rates and mixed-mode ratios obtained from the simulations using the submodeling technique were not in agreement with results obtained from full solid models.

Full f-p Shell Calculation of {sup 51}Ca and {sup 51}Sc

DOE Office of Scientific and Technical Information (OSTI.GOV)

Novoselsky, A.; Vallieres, M.; Laadan, O.

The spectra and the electromagnetic transitions of the nuclei {sup 51}Ca and {sup 51}Sc with 11 nucleons in the {ital f-p} shell are described in the nuclear shell-model approach by using two different two-body effective interactions. The full {ital f-p} shell basis functions are used with no truncation. The new parallel shell-model computer code DUPSM (Drexel University parallel shell model), that we recently developed, has been used. The calculations have been done on the MOSIX parallel machine at the Hebrew University of Jerusalem. {copyright} {ital 1997} {ital The American Physical Society}

On the growth and photocatalytic activity of the vertically aligned ZnO nanorods grafted by CdS shells

NASA Astrophysics Data System (ADS)

Zirak, M.; Moradlou, O.; Bayati, M. R.; Nien, Y. T.; Moshfegh, A. Z.

2013-05-01

We have studied systematically photocatalytic properties of the vertically aligned ZnO@CdS core-shell nanorods where the features were grown through a multistep procedure including sol-gel for the formation of ZnO seed layer, hydrothermal process to grow ZnO nanorods, and successive ion layer adsorption and reaction (SILAR) process to deposit CdS nanoshells onto the ZnO nanorods. Formation of the ZnO seed layer and vertically aligned ZnO nanorods (d ∼ 40 nm) with a hexagonal cross-section was confirmed by AFM and SEM imaging. Successful capping of ZnO nanorods with homogeneous CdS nanocrystallites (∼5 nm) was ascertained by HRTEM diffraction and imaging. Optical properties of the samples were also studied using UV-vis spectrophotometry. It was found that the absorption edge of the CdS shell has a red shift when its thickness increases. Photocatalytic activity of the samples was examined by photodecomposition of methylene blue under UV and visible lights where the maximum reaction rate constant was found to be 0.012 min-1 under UV illumination and 0.007 min-1 under visible light. The difference in catalytic activities of the ZnO@CdS core-shell nanorods under UV and visible irradiations was explained based upon the electronic structure as well as the arrangement of the energy levels in the ZnO@CdS core-shells. It is shown that the structure and photocatalytic efficiency of the samples can be tuned by manipulating the SILAR variables.

Detection of nuclei in 4D Nomarski DIC microscope images of early Caenorhabditis elegans embryos using local image entropy and object tracking

PubMed Central

Hamahashi, Shugo; Onami, Shuichi; Kitano, Hiroaki

2005-01-01

Background The ability to detect nuclei in embryos is essential for studying the development of multicellular organisms. A system of automated nuclear detection has already been tested on a set of four-dimensional (4D) Nomarski differential interference contrast (DIC) microscope images of Caenorhabditis elegans embryos. However, the system needed laborious hand-tuning of its parameters every time a new image set was used. It could not detect nuclei in the process of cell division, and could detect nuclei only from the two- to eight-cell stages. Results We developed a system that automates the detection of nuclei in a set of 4D DIC microscope images of C. elegans embryos. Local image entropy is used to produce regions of the images that have the image texture of the nucleus. From these regions, those that actually detect nuclei are manually selected at the first and last time points of the image set, and an object-tracking algorithm then selects regions that detect nuclei in between the first and last time points. The use of local image entropy makes the system applicable to multiple image sets without the need to change its parameter values. The use of an object-tracking algorithm enables the system to detect nuclei in the process of cell division. The system detected nuclei with high sensitivity and specificity from the one- to 24-cell stages. Conclusion A combination of local image entropy and an object-tracking algorithm enabled highly objective and productive detection of nuclei in a set of 4D DIC microscope images of C. elegans embryos. The system will facilitate genomic and computational analyses of C. elegans embryos. PMID:15910690

Synthesis and optical properties of core-multi-shell CdSe/CdS/ZnS quantum dots: Surface modifications

NASA Astrophysics Data System (ADS)

Ratnesh, R. K.; Mehata, Mohan Singh

2017-02-01

We report two port synthesis of CdSe/CdS/ZnS core-multi-shell quantum dots (Q-dots) and their structural properties. The multi-shell structures of Q-dots were developed by using successive ionic layer adsorption and reaction (SILAR) technique. The obtained Q-dots show high crystallinity with the step-wise adjustment of lattice parameters in the radial direction. The size of the core and core-shell Q-dots estimated by transmission electron microscopy images and absorption spectra is about 3.4 and 5.3 nm, respectively. The water soluble Q-dots (scheme-1) were prepared by using ligand exchange method, and the effect of pH was discussed regarding the variation of quantum yield (QY). The decrease of a lifetime of core-multi-shell Q-dots with respect to core CdSe indicates that the shell growth may be tuned by the lifetimes. Thus, the study clearly demonstrates that the core-shell approach can be used to substantially improve the optical properties of Q-dots desired for various applications.

Wave Function Engineering in CdSe/PbS Core/Shell Quantum Dots.

PubMed

Wieliczka, Brian M; Kaledin, Alexey L; Buhro, William E; Loomis, Richard A

2018-05-25

The synthesis of epitaxial CdSe/PbS core/shell quantum dots (QDs) is reported. The PbS shell grows in a rock salt structure on the zinc blende CdSe core, thereby creating a crystal structure mismatch through additive growth. Absorption and photoluminescence (PL) band edge features shift to lower energies with increasing shell thickness, but remain above the CdSe bulk band gap. Nevertheless, the profiles of the absorption spectra vary with shell growth, indicating that the overlap of the electron and hole wave functions is changing significantly. This leads to over an order of magnitude reduction of absorption near the band gap and a large, tunable energy shift, of up to 550 meV, between the onset of strong absorption and the band edge PL. While the bulk valence and conduction bands adopt an inverse type-I alignment, the observed spectroscopic behavior is consistent with a transition between quasi-type-I and quasi-type-II behavior depending on shell thickness. Three effective mass approximation models support this hypothesis and suggest that the large difference in effective masses between the core and shell results in hole localization in the CdSe core and a delocalization of the electron across the entire QD. These results show the tuning of wave functions and transition energies in CdSe/PbS nanoheterostructures with prospects for use in optoelectronic devices for luminescent solar concentration or multiexciton generation.

Geiger-Nuttall Law for Nuclei in Strong Electromagnetic Fields

NASA Astrophysics Data System (ADS)

Delion, D. S.; Ghinescu, S. A.

2017-11-01

We investigate the influence of a strong laser electromagnetic field on the α -decay rate by using the Hennenberger frame of reference. We introduce an adimensional parameter D =S0/R0, where R0 is the geometrical nuclear radius and S0˜√{I }/ω2 is a length parameter depending on the laser intensity I and frequency ω . We show that the barrier penetrability has a strong increase for intensities corresponding to D >Dcrit=1 , due to the fact that the resulting Coulomb potential becomes strongly anisotropic even for spherical nuclei. As a consequence, the contribution of the monopole term increases the barrier penetrability by 2 orders of magnitude, while the total contribution has an effect of 6 orders of magnitude at D ˜3 Dcrit. In the case of deformed nuclei, the electromagnetic field increases the penetrability by an additional order of magnitude for a quadrupole deformation β2˜0.3 . The influence of the electromagnetic field can be expressed in terms of a shifted Geiger-Nuttal law by a term depending on S0 and deformation.

Yrast excitations of neutron-rich nuclei around doubly magic Tin-132

NASA Astrophysics Data System (ADS)

Bhattacharyya, Pallab Kumar

Investigation of the yrast structures of neutron-rich nuclei around the double closed shell nucleus 132Sn is important in the understanding of simple two-body nucleon-nucleon interactions in that region. However conventional fusion-evaporation methods do not populate these nuclei and β-decay studies are useful only in studying low spin states. The spectroscopy of these nuclei from thick target γ-γ coincidence measurements of deep inelastic heavy ion collisions as well as from fission fragment γ-ray studies using large multidetector arrays are presented in this thesis. Analyses of data from the 124Sn + 665 MeV 136Xe and 130Te + 272 MeV 64Ni deep inelastic experiments identified new yrast isomers in the N = 80 nuclei 134Xe and 136Ba which de- excite by γ-ray cascades concluding with their known 4+/to2+ and 2+/to0+ transitions. The isomeric decay characteristics are presented and discussed in light of the systematic features in N = 80 isotones. By analyzing fission product γ-ray data measured at Eurogam II using a 248Cm source, yrast level structures of the two-, three- and four-proton N = 82 isotones 134Te, 135I and 136Xe were developed, and the proton-proton interactions from the two-body nucleus 134Te were used in interpreting 135I and 136Xe levels using shell model calculations. From the same data the yrast states in the N = 83 isotones 134Sb, 135Te, 136I and 137Xe were explored, and key proton-neutron interactions were extracted from the 134Sb level spectrum which were used in interpreting the levels of the other N = 83 isotones. Similarly yrast states in previously unexplored N = 81 isotones 132Sb and 133Te were also identified and interpreted with shell model calculations; the 132Sb level spectrum yielded important proton-neutron hole interactions. Neutron core-excited states at higher energies were also identified in most of these nuclei. For establishing isotopic assignments of unknown cascades, the γgamma cross coincidences between heavy and light

Fast Segmentation of Stained Nuclei in Terabyte-Scale, Time Resolved 3D Microscopy Image Stacks

PubMed Central

Stegmaier, Johannes; Otte, Jens C.; Kobitski, Andrei; Bartschat, Andreas; Garcia, Ariel; Nienhaus, G. Ulrich; Strähle, Uwe; Mikut, Ralf

2014-01-01

Automated analysis of multi-dimensional microscopy images has become an integral part of modern research in life science. Most available algorithms that provide sufficient segmentation quality, however, are infeasible for a large amount of data due to their high complexity. In this contribution we present a fast parallelized segmentation method that is especially suited for the extraction of stained nuclei from microscopy images, e.g., of developing zebrafish embryos. The idea is to transform the input image based on gradient and normal directions in the proximity of detected seed points such that it can be handled by straightforward global thresholding like Otsu’s method. We evaluate the quality of the obtained segmentation results on a set of real and simulated benchmark images in 2D and 3D and show the algorithm’s superior performance compared to other state-of-the-art algorithms. We achieve an up to ten-fold decrease in processing times, allowing us to process large data sets while still providing reasonable segmentation results. PMID:24587204

Fabricating a Shell-Core Delayed Release Tablet Using Dual FDM 3D Printing for Patient-Centred Therapy.

PubMed

Okwuosa, Tochukwu C; Pereira, Beatriz C; Arafat, Basel; Cieszynska, Milena; Isreb, Abdullah; Alhnan, Mohamed A

2017-02-01

Individualizing gastric-resistant tablets is associated with major challenges for clinical staff in hospitals and healthcare centres. This work aims to fabricate gastric-resistant 3D printed tablets using dual FDM 3D printing. The gastric-resistant tablets were engineered by employing a range of shell-core designs using polyvinylpyrrolidone (PVP) and methacrylic acid co-polymer for core and shell structures respectively. Filaments for both core and shell were compounded using a twin-screw hot-melt extruder (HME). CAD software was utilized to design a capsule-shaped core with a complementary shell of increasing thicknesses (0.17, 0.35, 0.52, 0.70 or 0.87 mm). The physical form of the drug and its integrity following an FDM 3D printing were assessed using x-ray powder diffractometry (XRPD), thermal analysis and HPLC. A shell thickness ≥0.52 mm was deemed necessary in order to achieve sufficient core protection in the acid medium. The technology proved viable for incorporating different drug candidates; theophylline, budesonide and diclofenac sodium. XRPD indicated the presence of theophylline crystals whilst budesonide and diclofenac sodium remained amorphous in the PVP matrix of the filaments and 3D printed tablets. Fabricated tablets demonstrated gastric resistant properties and a pH responsive drug release pattern in both phosphate and bicarbonate buffers. Despite its relatively limited resolution, FDM 3D printing proved to be a suitable platform for a single-process fabrication of delayed release tablets. This work reveals the potential of dual FDM 3D printing as a unique platform for personalising delayed release tablets to suit an individual patient's needs.

High performance of PbSe/PbS core/shell quantum dot heterojunction solar cells: short circuit current enhancement without the loss of open circuit voltage by shell thickness control.

PubMed

Choi, Hyekyoung; Song, Jung Hoon; Jang, Jihoon; Mai, Xuan Dung; Kim, Sungwoo; Jeong, Sohee

2015-11-07

We fabricated heterojunction solar cells with PbSe/PbS core shell quantum dots and studied the precisely controlled PbS shell thickness dependency in terms of optical properties, electronic structure, and solar cell performances. When the PbS shell thickness increases, the short circuit current density (JSC) increases from 6.4 to 11.8 mA cm(-2) and the fill factor (FF) enhances from 30 to 49% while the open circuit voltage (VOC) remains unchanged at 0.46 V even with the decreased effective band gap. We found that the Fermi level and the valence band maximum level remain unchanged in both the PbSe core and PbSe/PbS core/shell with a less than 1 nm thick PbS shell as probed via ultraviolet photoelectron spectroscopy (UPS). The PbS shell reduces their surface trap density as confirmed by relative quantum yield measurements. Consequently, PbS shell formation on the PbSe core mitigates the trade-off relationship between the open circuit voltage and the short circuit current density. Finally, under the optimized conditions, the PbSe core with a 0.9 nm thick shell yielded a power conversion efficiency of 6.5% under AM 1.5.

Bandgap engineered reverse type-I CdTe/InP/ZnS core-shell nanocrystals for the near-infrared.

PubMed

Kim, Sunghoon; Shim, Wooyoung; Seo, Heonjin; Hyun Bae, Je; Sung, Jaeyoung; Choi, Seung Hong; Moon, Woo Kyung; Lee, Gwang; Lee, Bunyeoul; Kim, Sang-Wook

2009-03-14

New quantum dots were fabricated with a core/shell/shell structure consisting of CdTe core/InP shell/ZnS shell of which the InP shell causes a red-shift to the NIR region and the ZnS shell imparts photo-stability; toxicity tests on mammalian cells and NIR imaging of a mouse highlight their potential applications in biomedical imaging.

N3LO NN interaction adjusted to light nuclei in ab exitu approach

DOE PAGES

Shirokov, A. M.; Shin, I. J.; Kim, Y.; ...

2016-08-09

Here, we use phase-equivalent transformations to adjust off-shell properties of similarity renormalization group evolved chiral effective field theory NN interaction (Idaho N3LO) to fit selected binding energies and spectra of light nuclei in an ab exitu approach. Then, we test the transformed interaction on a set of additional observables in light nuclei to verify that it provides reasonable descriptions of these observables with an apparent reduced need for three- and many-nucleon interactions.

Cross-shell excitations in Si 31

DOE PAGES

Tai, P. -L.; Tabor, S. L.; Lubna, R. S.; ...

2017-07-28

The Si-31 nucleus was produced through the O-18(18O, an) fusion-evaporation reaction at E-lab = 24 MeV. Evaporated a particles from the reaction were detected and identified in the Microball detector array for channel selection. Multiple gamma-ray coincidence events were detected in Gammasphere. The energy and angle information for the alpha particles was used to determine the Si-31 recoil kinematics on an event-by-event basis for a more accurate Doppler correction. A total of 22 new states and 52 new gamma transitions were observed, including 14 from states above the neutron separation energy. The positive-parity states predicted by the shell-model calculations inmore » the sd model space agree well with experiment. The negative-parity states were compared with shell-model calculations in the psdpf model space with some variations in the N = 20 shell gap. The best agreement was found with a shell gap intermediate between that originally used for A approximate to 20 nuclei and that previously adapted for P-32,P-34. This variation suggests the need for a more universal cross-shell interaction.« less

Interplay between Surface Chemistry, Precursor Reactivity, and Temperature Determines Outcome of ZnS Shelling Reactions on CuInS2 Nanocrystals

PubMed Central

2018-01-01

ZnS shelling of I–III–VI2 nanocrystals (NCs) invariably leads to blue-shifts in both the absorption and photoluminescence spectra. These observations imply that the outcome of ZnS shelling reactions on I–III–VI2 colloidal NCs results from a complex interplay between several processes taking place in solution, at the surface of, and within the seed NC. However, a fundamental understanding of the factors determining the balance between these different processes is still lacking. In this work, we address this need by investigating the impact of precursor reactivity, reaction temperature, and surface chemistry (due to the washing procedure) on the outcome of ZnS shelling reactions on CuInS2 NCs using a seeded growth approach. We demonstrate that low reaction temperatures (150 °C) favor etching, cation exchange, and alloying regardless of the precursors used. Heteroepitaxial shell overgrowth becomes the dominant process only if reactive S- and Zn-precursors (S-ODE/OLAM and ZnI2) and high reaction temperatures (210 °C) are used, although a certain degree of heterointerfacial alloying still occurs. Remarkably, the presence of residual acetate at the surface of CIS seed NCs washed with ethanol is shown to facilitate heteroepitaxial shell overgrowth, yielding for the first time CIS/ZnS core/shell NCs displaying red-shifted absorption spectra, in agreement with the spectral shifts expected for a type-I band alignment. The insights provided by this work pave the way toward the design of improved synthesis strategies to CIS/ZnS core/shell and alloy NCs with tailored elemental distribution profiles, allowing precise tuning of the optoelectronic properties of the resulting materials. PMID:29657360

Study of near-stability nuclei populated as fission fragments in heavy-ion fusion reactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fotiadis, Nikolaos; Nelson, Ronald O; Devlin, Matthew

2010-01-01

Examples are presented to illustrate the power of prompt {gamma}-ray spectroscopy of fission fragments from compound nuclei with A {approx} 200 formed in fusion-evaporation reactions in experiments using the Gammasphere Ge-detector array. Complementary methods, such as Coulomb excitation and deep-inelastic processes, are also discussed. In other cases (n, xn{gamma}) reactions on stable isotopes have been used to establish neutron excitation functions for {gamma}-rays using a pulsed 'white'-neutron source, coupled to a high-energy-resolution germanium-detector array. The excitation functions can unambiguously assign {gamma}-rays to a specific reaction product. Results from all these methods bridge the gaps in the systematics of high-spin statesmore » between the neutron-deficient and neutron-rich nuclei. Results near shell closures should motivate new shell model calculations.« less

Self-template synthesis of double shelled ZnS-NiS1.97 hollow spheres for electrochemical energy storage

NASA Astrophysics Data System (ADS)

Wei, Chengzhen; Ru, Qinglong; Kang, Xiaoting; Hou, Haiyan; Cheng, Cheng; Zhang, Daojun

2018-03-01

In this work, double shelled ZnS-NiS1.97 hollow spheres have been achieved via a simple self-template route, which involves the synthesis of Zn-Ni solid spheres precursors as the self-template and then transformation into double shelled ZnS-NiS1.97 hollow spheres by sulfidation treatment. The as-prepared double shelled ZnS-NiS1.97 hollow spheres possess a high surface area (105.26 m2 g-1) and porous structures. Benefiting from the combined characteristics of novel structures, multi-component, high surface area and porous. When applied as electrode materials for supercapacitors, the double shelled ZnS-NiS1.97hollow spheres deliver a large specific capacitance of 696.8C g-1 at 5.0 A g-1 and a remarkable long lifespan cycling stability (less 5.5% loss after 6000 cycles). Moreover, an asymmetric supercapacitor (ASC) was assembled by utilizing ZnS-NiS1.97 (positive electrode) and activated carbon (negative electrode) as electrode materials. The as-assembled device possesses an energy density of 36 W h kg-1, which can be yet retained 25.6 W h kg-1 even at a power density of 2173.8 W Kg-1, indicating its promising applications in electrochemical energy storage. More importantly, the self-template route is a simple and versatile strategy for the preparation of metal sulfides electrode materials with desired structures, chemical compositions and electrochemical performances.

Synthesis of Superheavy Nuclei in 48CA-INDUCED Reactions

NASA Astrophysics Data System (ADS)

Oganessian, Yu. Ts.; Utyonkov, V. K.; Lobanov, Yu. V.; Abdullin, F. Sh.; Polyakov, A. N.; Sagaidak, R. N.; Shirokovsky, I. V.; Tsyganov, Yu. S.; Voinov, A. A.; Gulbekian, G. G.; Bogomolov, S. L.; Gikal, B. N.; Mezentsev, A. N.; Iliev, S.; Subbotin, V. G.; Sukhov, A. M.; Subotic, K.; Zagrebaev, V. I.; Vostokin, G. K.; Itkis, M. G.; Moody, K. J.; Patin, J. B.; Shaughnessy, D. A.; Stoyer, M. A.; Stoyer, N. J.; Wilk, P. A.; Kenneally, J. M.; Landrum, J. H.; Wild, J. F.; Lougheed, R. W.

2008-11-01

Thirty-four new nuclides with Z = 104-116, 118 and N = 161-177 have been synthesized in the complete-fusion reactions of 238U, 237Np, 242,244Pu, 243Am, 245,248Cm, and 249Cf targets with 48Ca beams. The masses of evaporation residues were identified through measurements of the excitation functions of the xn-evaporation channels and from cross bombardments. The decay properties of the new nuclei agree with those of previously known heavy nuclei and with predictions from different theoretical models. A discussion of self-consistent interpretations of all observed decay chains originating from the parent isotopes 282,283112, 282113, 286-289114, 287,288115, 290-293116, and 294118 is presented. Decay energies and lifetimes of the neutron-rich superheavy nuclei as well as their production cross sections indicate a considerable increase in the stability of nuclei with an increasing number of neutrons, which agrees with the predictions of theoretical models concerning the decisive dependence of the structure and radioactive properties of superheavy elements on their proximity to the nuclear shells with N = 184 and Z = 114.

Photoelectrodes based on 2D opals assembled from Cu-delafossite double-shelled microspheres for an enhanced photoelectrochemical response.

PubMed

Oh, Yunjung; Yang, Wooseok; Tan, Jeiwan; Lee, Hyungsoo; Park, Jaemin; Moon, Jooho

2018-02-22

Although a unique light-harvesting property was recently demonstrated in a photocathode based on 2-dimensional (2D) opals of CuFeO 2 -shelled SiO 2 microspheres, the performance of a monolayer of ultra-thin CuFeO 2 -shelled microspheres is limited by ineffective charge separation. Herein, we propose an innovative design rule, in which an inner CuFeO 2 /outer CuAlO 2 double-shelled heterojunction is formed on each partially etched microsphere to obtain a hexagonally assembled 2D opal photoelectrode. Our Cu-delafossite double-shelled photocathode shows a dramatically improved charge separation capability, with a 9-fold increase in the photocurrent compared to that of the single-shelled counterpart. Electrochemical impedance spectroscopy clearly confirms the reduced charge transport/transfer resistance associated with the Cu-delafossite double-shelled photocathode, while surface photovoltage spectra reveal enhanced polarization of the photogenerated carrier, indicating improved charge separation capability with the aid of the heterojunction. Our finding sheds light on the importance of heterojunction interfaces in achieving optimal charge separation in opal architectures as well as the inner-shell/electrolyte interface to expedite charge separation/transport.

Synthesis of robust water-soluble ZnS:Mn/SiO2 core/shell nanoparticles

NASA Astrophysics Data System (ADS)

Sun, Jing; Zhuang, Jiaqi; Guan, Shaowei; Yang, Wensheng

2008-04-01

Water-soluble Mn doped ZnS (ZnS:Mn) nanocrystals synthesized by using 3-mercaptopropionic acid (MPA) as stabilizer were homogeneously coated with a dense silica shell through a multi-step procedure. First, 3-mercaptopropyl triethoxy silane (MPS) was used to replace MPA on the particle surface to form a vitreophilic layer for further silica deposition under optimal experimental conditions. Then a two-step silica deposition was performed to form the final water-soluble ZnS:Mn/SiO2 core/shell nanoparticles. The as-prepared core/shell nanoparticles show little change in fluorescence intensity in a wide range of pH value.

Dependence of nonlinear optical properties of Ag2S@ZnS core-shells on Zinc precursor and capping agent

NASA Astrophysics Data System (ADS)

Dehghanipour, M.; Khanzadeh, M.; Karimipour, M.; Molaei, M.

2018-03-01

In this research, four different types of Ag2S@ZnS core-shells were synthesized and their nonlinear optical (NLO) properties were investigated using a Z-scan technique by a 532 nm laser diode. Here, Ag2S and ZnS nanoparticles were also synthesized and their NLO properties were compared with Ag2S@ZnS core-shells. It was observed that the NLO properties of Ag2S@ZnS quantum dots significantly increased by increasing the values of Zn(NO3)2 and thioglycolic acid (TGA). It was also observed that the NLO properties of Ag2S@ZnS core-shells for 0.1 g of Zn(NO3)2 and 7000 μl TGA is higher than sole Ag2S and ZnS nanoparticles. In open aperture Z-scan curve of ZnS sample, a saturable absorption peak was observed and this peak was seen also in type of Ag2S@ZnS nanoparticles which the value of Zn(NO3)2 much more.

Confidence Testing of Shell 405 and S-405 Catalysts in a Monopropellant Hydrazine Thruster

NASA Technical Reports Server (NTRS)

McRight, Patrick; Popp, Chris; Pierce, Charles; Turpin, Alicia; Urbanchock, Walter; Wilson, Mike

2005-01-01

As part of the transfer of catalyst manufacturing technology from Shell Chemical Company (Shell 405 catalyst manufactured in Houston, Texas) to Aerojet (S-405 manufactured in Redmond, Washington), Aerojet demonstrated the equivalence of S-405 and Shell 405 at beginning of life. Some US aerospace users expressed a desire to conduct a preliminary confidence test to assess end-of-life characteristics for S-405. NASA Marshall Space Flight Center (MSFC) and Aerojet entered a contractual agreement in 2004 to conduct a confidence test using a pair of 0.2-lbf MR-103G monopropellant hydrazine thrusters, comparing S-405 and Shell 405 side by side. This paper summarizes the formulation of this test program, explains the test matrix, describes the progress of the test, and analyzes the test results. This paper also includes a discussion of the limitations of this test and the ramifications of the test results for assessing the need for future qualification testing in particular hydrazine thruster applications.

Green synthesis of CuInS2/ZnS core-shell quantum dots by facile solvothermal route with enhanced optical properties

NASA Astrophysics Data System (ADS)

Jindal, Shikha; Giripunje, Sushama M.; Kondawar, Subhash B.; Koinkar, Pankaj

2018-03-01

We report an eco-friendly green synthesis of highly luminescent CuInS2/ZnS core-shell quantum dots (QDs) with average particle size ∼ 3.9 nm via solvothermal process. The present study embodies the intensification of CuInS2/ZnS QDs properties by the shell growth on the CuInS2 QDs. The as-prepared CuInS2 core and CuInS2/ZnS core-shell QDs have been characterized using a range of optical and structural techniques. By adopting a low temperature growth of CuInS2 core and high temperature growth of CuInS2/ZnS core-shell growth, the tuning of absorption and photoluminescence emission spectra were observed. Optical absorption and photoluminescence spectroscopy probe the effect of ZnS passivation on the electronic structure of the CuInS2 dots. In addition, QDs have been scrutinized using ultra violet photoelectron spectroscopy (UPS) to explore their electronic band structure. The band level positions of CuInS2 and CuInS2/ZnS QDs suffices the demand of non-toxic acceptor material for electronic devices. The variation in electronic energy levels of CuInS2 core with the coating of wide band gap ZnS shell influence the removal of trap assisted recombination on the surface of the core. QDs exhibited tunable emission from red to orange region. These studies reveal the feasibility of QDs in photovoltaic and light emitting diodes.

Piezo-phototronic Effect Enhanced UV/Visible Photodetector Based on Fully Wide Band Gap Type-II ZnO/ZnS Core/Shell Nanowire Array.

PubMed

Rai, Satish C; Wang, Kai; Ding, Yong; Marmon, Jason K; Bhatt, Manish; Zhang, Yong; Zhou, Weilie; Wang, Zhong Lin

2015-06-23

A high-performance broad band UV/visible photodetector has been successfully fabricated on a fully wide bandgap ZnO/ZnS type-II heterojunction core/shell nanowire array. The device can detect photons with energies significantly smaller (2.2 eV) than the band gap of ZnO (3.2 eV) and ZnS (3.7 eV), which is mainly attributed to spatially indirect type-II transition facilitated by the abrupt interface between the ZnO core and ZnS shell. The performance of the device was further enhanced through the piezo-phototronic effect induced lowering of the barrier height to allow charge carrier transport across the ZnO/ZnS interface, resulting in three orders of relative responsivity change measured at three different excitation wavelengths (385, 465, and 520 nm). This work demonstrates a prototype UV/visible photodetector based on the truly wide band gap semiconducting 3D core/shell nanowire array with enhanced performance through the piezo-phototronic effect.

Valence and L-shell photoionization of Cl-like argon using R-matrix techniques

NASA Astrophysics Data System (ADS)

Tyndall, N. B.; Ramsbottom, C. A.; Ballance, C. P.; Hibbert, A.

2016-02-01

Photoionization cross-sections are obtained using the relativistic Dirac Atomic R-matrix Codes (DARC) for all valence and L-shell energy ranges between 27 and 270 eV. A total of 557 levels arising from the dominant configurations 3s23p4, 3s3p5, 3p6, 3s23p3[3d, 4s, 4p], 3p53d, 3s23p23d2, 3s3p43d, 3s3p33d2 and 2s22p53s23p5 have been included in the target wavefunction representation of the Ar III ion, including up to 4p in the orbital basis. We also performed a smaller Breit-Pauli (BP) calculation containing the lowest 124 levels. Direct comparisons are made with previous theoretical and experimental work for both valence shell and L-shell photoionization. Excellent agreement was found for transitions involving the 2Po initial state to all allowed final states for both calculations across a range of photon energies. A number of resonant states have been identified to help analyse and explain the nature of the spectra at photon energies between 250 and 270 eV.

Low energy dipole strength from large scale shell model calculations

NASA Astrophysics Data System (ADS)

Sieja, Kamila

2017-09-01

Low energy enhancement of radiative strength functions has been deduced from experiments in several mass regions of nuclei. Such an enhancement is believed to impact the calculated neutron capture rates which are crucial input for reaction rates of astrophysical interest. Recently, shell model calculations have been performed to explain the upbend of the γ-strength as due to the M1 transitions between close-lying states in the quasi-continuum in Fe and Mo nuclei. Beyond mean-↓eld calculations in Mo suggested, however, a non-negligible role of electric dipole in the low energy enhancement. So far, no calculations of both dipole components within the same theoretical framework have been presented in this context. In this work we present newly developed large scale shell model appraoch that allows to treat on the same footing natural and non-natural parity states. The calculations are performed in a large sd - pf - gds model space, allowing for 1p{1h excitations on the top of the full pf-shell con↓guration mixing. We restrict the discussion to the magnetic part of the dipole strength, however, we calculate for the ↓rst time the magnetic dipole strength between states built of excitations going beyond the classical shell model spaces. Our results corroborate previous ↓ndings for the M1 enhancement for the natural parity states while we observe no enhancement for the 1p{1h contributions. We also discuss in more detail the e↑ects of con↓guration mixing limitations on the enhancement coming out from shell model calculations.

Properties of Nuclei up to A = 16 using Local Chiral Interactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lonardoni, Diego; Carlson, Joseph; Gandolfi, Stefano

Here, we report accurate quantum Monte Carlo calculations of nuclei up to A = 16 based on local chiral two- and three-nucleon interactions up to next-to-next-to-leading order. We examine the theoretical uncertainties associated with the chiral expansion and the cutoff in the theory, as well as the associated operator choices in the three-nucleon interactions. While in light nuclei the cutoff variation and systematic uncertainties are rather small, in 16O these can be significant for large coordinate-space cutoffs. Overall, we show that chiral interactions constructed to reproduce properties of very light systems and nucleon-nucleon scattering give an excellent description of bindingmore » energies, charge radii, and form factors for all these nuclei, including open-shell systems in A = 6 and 12.« less

Properties of Nuclei up to A = 16 using Local Chiral Interactions

DOE PAGES

Lonardoni, Diego; Carlson, Joseph; Gandolfi, Stefano; ...

2018-03-22

Here, we report accurate quantum Monte Carlo calculations of nuclei up to A = 16 based on local chiral two- and three-nucleon interactions up to next-to-next-to-leading order. We examine the theoretical uncertainties associated with the chiral expansion and the cutoff in the theory, as well as the associated operator choices in the three-nucleon interactions. While in light nuclei the cutoff variation and systematic uncertainties are rather small, in 16O these can be significant for large coordinate-space cutoffs. Overall, we show that chiral interactions constructed to reproduce properties of very light systems and nucleon-nucleon scattering give an excellent description of bindingmore » energies, charge radii, and form factors for all these nuclei, including open-shell systems in A = 6 and 12.« less

Stratigraphy Identification with Emphasis to Shells Layer using 2-D Electrical Resistivity Method at Guar Kepah, Penang

NASA Astrophysics Data System (ADS)

Rosli, Najmiah; Mansor, Hafizuddin; Ismail, N. A.; Masnan, S. S. K.; Saidin, M.

2018-04-01

2-D electrical resistivity method was done at an archaeological site in Guar Kepah, Penang, to determine its stratigraphy with emphasis to shells layer. This study aims to guide the archaeological studies where many prehistoric findings are related to shells and also for engineering purposes as an archaeological gallery is to be built there. Results show that the area is composed of three unconsolidated soil strata where the uppermost layer is sandy-clay, followed by shells layer, and lastly sandy layer. The shells layer is undulating with similar thickness throughout the site, but thickens at the northern part of the study area. The depth of the shells layer however, is different at different parts of the site.

Multinucleon transfer reactions – a pathway to new heavy and superheavy nuclei?

NASA Astrophysics Data System (ADS)

Heinz, Sophie

2018-05-01

Recently, we reported the observation of several new neutron-deficient isotopes with proton numbers Z ≥ 92 in collisions of 48Ca + 248Cm at the Coulomb barrier. The peculiarity is that these nuclei were produced in deep inelastic multinucleon transfer reactions, a method which is presently discussed as a possible new pathway to enter so far unknown regions in the upper part of the Chart of Nuclides. Of particular interest are multinucleon transfer reactions as a possible means to produce neutron-rich superheavy nuclei and nuclei along the magic neutron shell N = 126. Based on present-day physical and technical state-of-the art, we will discuss the question how big are our chances to enter these regions by applying multinucleon transfer reactions.

Synthesis and Luminescence Properties of Core/Shell ZnS:Mn/ZnO Nanoparticles.

PubMed

Jiang, Daixun; Cao, Lixin; Liu, Wei; Su, Ge; Qu, Hua; Sun, Yuanguang; Dong, Bohua

2009-01-01

In this paper the influence of ZnO shell thickness on the luminescence properties of Mn-doped ZnS nanoparticles is studied. Transmission electron microscopy (TEM) images showed that the average diameter of ZnS:Mn nanoparticles is around 14 nm. The formation of ZnO shells on the surface of ZnS:Mn nanoparticles was confirmed by X-ray diffraction (XRD) patterns, high-resolution TEM (HRTEM) images, and X-ray photoelectron spectroscopy (XPS) measurements. A strong increase followed by a gradual decline was observed in the room temperature photoluminescence (PL) spectra with the thickening of the ZnO shell. The photoluminescence excitation (PLE) spectra exhibited a blue shift in ZnO-coated ZnS:Mn nanoparticles compared with the uncoated ones. It is shown that the PL enhancement and the blue shift of optimum excitation wavelength are led by the ZnO-induced surface passivation and compressive stress on the ZnS:Mn cores.

Applying a Qualitative Modeling Shell to Process Diagnosis: The Caster System.

DTIC Science & Technology

1986-03-01

Process Diagnosis: The Caster System by Timothy F. Thompson and William J. Clancey Department of Computer Science Stanford University Stanford, CA 94303...MODELING SHELL TO PROCESS DIAGNOSIS: THE CASTER SYSTEM 12 PERSONAL AUTHOR(S) TIMOTHY F. THOMPSON. WESTINGHOUSE R&D CENTER, WILLIAM CLANCEY, STANFORD...editions are obsolete. Applying a Qualitative Modeling Shell to Process Diagnosis: The Caster System by Timothy F. Thompson, Westinghouse R&D Center

Shell Structure Water Cellar’s Rapid Construct Technology

NASA Astrophysics Data System (ADS)

Xian Zhuang, Wen; Qing Yin, De; Chen, Shu Fa

2018-05-01

Tradition concrete water cellar’s problems, such as high cost, long construction term, easy to crack, are pointed out. A new construct method, and it’s matching airbag mould, of constructing concrete shell structure water cellars, are introduced. Combine with full-scale verifying cellar’s construct test, full-load water storage test, analyzed the technology in terms of construction term, cost, crack resistance, air bag pressure etc. It is believed that this new technology can successfully solve the problems that tradition technology has, and it will have a good prospect in rainfall resources utilization.

Asymptotic Giant Branch stars as a source of short-lived radioactive nuclei in the solar nebula

NASA Astrophysics Data System (ADS)

Wasserburg, G. J.; Busso, M.; Gallino, R.; Raiteri, C. M.

1994-03-01

We carried out a theoretical evaluation of the contribution of Asymptotic Giant Branch (AGB) stars to some short-lived (106 less than or equal to Tau-bar less than or equal to 2 x 107 yr) isotopes in the Interstellar Medium (ISM) and in the early solar system using stellar model calculations for thermally pulsing evolutionary phases of low-mass stars. The yields of s-process nuclei in the convective He-shell for different neutron exposures tau0 were obtained, and AGB stars were shown to produce several radioactive nuclei (especially Pd-107, Pb-205, Fe-60, Zr-93, Tc-99, Cs-135, and Hf-182) in diferent amounts. Assuming either contamination of the solar nebula from a single AGB star or models for continuous injection and mixing from many stars into the ISM, we calculate the ratios of radioactive to stable nuclei at the epoch of the Sun's formation. The dilution factor between the AGB ejecta and the early solar system matter is obtained by matching the observed Pd-107/Pd-108 and depends on the value of tau0. It is found that small masses MHe of He-shell material (10-4-10-7 solar mass) enriched in s-process nuclei are sufficient to contaminate 1 solar mass of the ISM to produce the Pd-107 found in the early solar system. Predictions are made for all of the other radioactive isotopes. The optimal model to explain several observed radioactive species at different states of the proto-solar nebula involves a single AGB star with a low neutron exposure (tau0 = 0.03 mbarn-1) which contaminated the cloud with a dilution factor of MHe/solar mass approximately 1.5 x 10-4. This will also contribute newly synthesized stable s-process nuclei in the amount of approximately 10-4 of their abundances already present in the proto-solar cloud. Variations in the degree of homogenization (approximately 30%) of the injected material may account for some of the small general isotopic anomalies found in meteorites. It is also found that Fe-60 is produced in small but significant quantities

Emission Characteristics of InGaN/GaN Core-Shell Nanorods Embedded in a 3D Light-Emitting Diode.

PubMed

Jung, Byung Oh; Bae, Si-Young; Lee, Seunga; Kim, Sang Yun; Lee, Jeong Yong; Honda, Yoshio; Amano, Hiroshi

2016-12-01

We report the selective-area growth of a gallium nitride (GaN)-nanorod-based InGaN/GaN multiple-quantum-well (MQW) core-shell structure embedded in a three-dimensional (3D) light-emitting diode (LED) grown by metalorganic chemical vapor deposition (MOCVD) and its optical analysis. High-resolution transmission electron microscopy (HR-TEM) observation revealed the high quality of the GaN nanorods and the position dependence of the structural properties of the InGaN/GaN MQWs on multiple facets. The excitation and temperature dependences of photoluminescence (PL) revealed the m-plane emission behaviors of the InGaN/GaN core-shell nanorods. The electroluminescence (EL) of the InGaN/GaN core-shell-nanorod-embedded 3D LED changed color from green to blue with increasing injection current. This phenomenon was mainly due to the energy gradient and deep localization of the indium in the selectively grown InGaN/GaN core-shell MQWs on the 3D architecture.

Increased shell entropy as an explanation for observed decreased shell areal densities in OMEGA implosions

NASA Astrophysics Data System (ADS)

Hoffman, Nelson; Herrmann, Hans; Kim, Yongho

2014-10-01

A reduced ion-kinetic (RIK) model used in hydrodynamic simulations has had some success in explaining time- and space-averaged observables characterizing the fusion fuel in hot low-density ICF capsule implosions driven by 1-ns 60-beam laser pulses at OMEGA. But observables characterizing the capsule shell, e.g., the areal density of 12C in a plastic shell, have proved harder to explain. Recently we have found that assuming the shell has higher entropy than expected in a 1D laser-driven RIK simulation allows an explanation of the observed values of 12C areal density, and its dependence on initial shell thickness in a set of DT-filled plastic capsules. If, for example, a 15- μm CH shell implodes on an adiabat two to three times higher than predicted in a typical unmodified RIK simulation, the calculated burn-averaged shell areal density decreases from ~80 mg/cm2 in the unmodified simulation to the observed value of ~25 mg/cm2. We discuss possible mechanisms that could lead to increased entropy in such implosions. Research supported by U.S. Department of Energy under Contract DE-AC52-06NA25396.

Nuclear Masses in the A=80 Region of Nuclei

NASA Astrophysics Data System (ADS)

Cuka, N.; Gadala-Maria, A.; Aprahamian, A.

1996-05-01

Nucleosynthesis in explosive hydrogen burning at high temperatures above 8x10^8 K is characterized by the rp-process. A recent study^1 of the reaction flow and their associated time scales showed that the reaction path may in fact proceed well beyond the A=80 region of nuclei. An accurate simulation of the nucleosynthesis and energy generation of this process strongly depends on reliable nuclear physics input parameters such as masses, lifetimes, and reaction rates. We have extended the use of the simple P-parametrization^2,3 that had been applied to the characterization of the structure contributions to the nuclear masses in the actinides to include the A=80 region. The results will be presented along with predictions of masses for presently unknown masses of nuclei along the rp-process path. ^1 R. Wallace and S. Woosley, Ap. J. Suppl. 45, 389 (81). ^2 R. F. Casten, D.S. Brenner and P.E. Haustein, Phys. Rev. Lett. 58, 658 (87). ^3 P. Haustein, D.S. Brenner and R.F. Casten, Phys. Rev. C 38, 467 (88).

Beta-Decay Rates for Exotic Nuclei and R-Process Nucleosynthesis

NASA Astrophysics Data System (ADS)

Suzuki, Toshio; Yoshida, Takashi; Wanajo, Shinya; Kajino, Toshitaka; Otsuka, Takaharu

Beta-decay rates for exotic nuclei at N = 126 relevant to r-process nucleosynthesis are studied by shell-model calculations. The half-lives obtained are used to study r-process nucleosynthesis in core-collapse supernova explosions and binary neutron star mergers. The element abundances are obtained up to the third peak as well as beyond the peak region up to uranium.

Biomaterial shell bending with 3D-printed templates in vertical and alveolar ridge augmentation: a technical note.

PubMed

Draenert, Florian G; Gebhart, Florian; Mitov, Gergo; Neff, Andreas

2017-06-01

Alveolar ridge and vertical augmentations are challenging procedures in dental implantology. Even material blocks with an interconnecting porous system are never completely resorbed. Shell techniques combined with autologous bone chips are therefore the gold standard. Using biopolymers for these techniques is well documented. We applied three-dimensional (3-D) techniques to create an individualized bending model for the adjustment of a plane biopolymer membrane made of polylactide. Two cases with a vertical alveolar ridge defect in the maxilla were chosen. The cone beam computed tomography data were processed with a 3-D slicer and the Autodesk Meshmixer to generate data about the desired augmentation result. STL data were used to print a bending model. A 0.2-mm poly-D, L-lactic acid membrane (KLS Matin Inc., Tuttlingen, Germany) was bended accordingly and placed into the defect via a tunnel approach in both cases. A mesh graft of autologous bone chips and hydroxylapatite material was augmented beneath the shell, which was fixed with osteosynthesis screws. The operative procedure was fast and without peri- or postoperative complications or complaints. The panoramic x-ray showed correct fitting of the material in the location. Bone quality at the time of implant placement was type II, resulting in good primary stability. A custom-made 3-D model for bending confectioned biomaterial pieces is an appropriate method for individualized adjustment in shell techniques. The advantages over direct printing of the biomaterial shell and products on the market, such as the Xyoss shell (Reoss Inc., Germany), include cost-efficiency and avoidance of regulatory issues. Copyright © 2016 Elsevier Inc. All rights reserved.

Heaviest Nuclei: New Element with Atomic Number 117

ScienceCinema

Oganessian, Yuri

2018-01-24

One of the fundamental outcomes of the nuclear shell model is the prediction of the 'stability islands' in the domain of the hypothetical super heavy elements. The talk is devoted to the experimental verification of these predictions - the synthesis and study of both the decay and chemical properties of the super heavy elements. The discovery of a new chemical element with atomic number Z=117 is reported. The isotopes 293117 and 294117 were produced in fusion reactions between 48Ca and 249Bk. Decay chains involving 11 new nuclei were identified by means of the Dubna gas-filled recoil separator. The measured decay properties show a strong rise of stability for heavier isotopes with Z =111, validating the concept of the long sought island of enhanced stability for heaviest nuclei.

D1 and D2 antagonists reverse the effects of appetite suppressants on weight loss, food intake, locomotion, and rebalance spiking inhibition in the rat NAc shell

PubMed Central

Kalyanasundar, B.; Perez, Claudia I.; Luna, Alvaro; Solorio, Jessica; Moreno, Mario G.; Elias, David; Simon, Sidney A.

2015-01-01

Obesity is a worldwide health problem that has reached epidemic proportions. To ameliorate this problem, one approach is the use of appetite suppressants. These compounds are frequently amphetamine congeners such as diethylpropion (DEP), phentermine (PHEN), and bupropion (BUP), whose effects are mediated through serotonin, norepinephrine, and dopaminergic pathways. The nucleus accumbens (NAc) shell receives dopaminergic inputs and is involved in feeding and motor activity. However, little is known about how appetite suppressants modulate its activity. Therefore, we characterized behavioral and neuronal NAc shell responses to short-term treatments of DEP, PHEN, and BUP. These compounds caused a transient decrease in weight and food intake while increasing locomotion, stereotypy, and insomnia. They evoked a large inhibitory imbalance in NAc shell spiking activity that correlated with the onset of locomotion and stereotypy. Analysis of the local field potentials (LFPs) showed that all three drugs modulated beta, theta, and delta oscillations. These oscillations do not reflect an aversive-malaise brain state, as ascertained from taste aversion experiments, but tracked both the initial decrease in weight and food intake and the subsequent tolerance to these drugs. Importantly, the appetite suppressant-induced weight loss and locomotion were markedly reduced by intragastric (and intra-NAc shell) infusions of dopamine antagonists SCH-23390 (D1 receptor) or raclopride (D2 receptor). Furthermore, both antagonists attenuated appetite suppressant-induced LFP oscillations and partially restored the imbalance in NAc shell activity. These data reveal that appetite suppressant-induced behavioral and neuronal activity recorded in the NAc shell depend, to various extents, on dopaminergic activation and thus point to an important role for D1/D2-like receptors (in the NAc shell) in the mechanism of action for these anorexic compounds. PMID:25972577

Multi-Scale Analyses of Three Dimensional Woven Composite 3D Shell With a Cut Out Circle

NASA Astrophysics Data System (ADS)

Nguyen, Duc Hai; Wang, Hu

2018-06-01

A composite material are made by combining two or more constituent materials to obtain the desired material properties of each product type. The matrix material which can be polymer and fiber is used as reinforcing material. Currently, the polymer matrix is widely used in many different fields with differently designed structures such as automotive structures and aviation, aerospace, marine, etc. because of their excellent mechanical properties; in addition, they possess the high level of hardness and durability together with a significant reduction in weight compared to traditional materials. However, during design process of structure, there will be many interruptions created for the purpose of assembling the structures together or for many other design purposes. Therefore, when this structure is subject to load-bearing, its failure occurs at these interruptions due to stress concentration. This paper proposes multi-scale modeling and optimization strategies in evaluation of the effectiveness of fiber orientation in an E-glass/Epoxy woven composite 3D shell with circular holes at the center investigated by FEA results. A multi-scale model approach was developed to predict the mechanical behavior of woven composite 3D shell with circular holes at the center with different designs of material and structural parameters. Based on the analysis result of laminae, we have found that the 3D shell with fiber direction of 450 shows the best stress and strain bearing capacity. Thus combining several layers of 450 fiber direction in a multi-layer composite 3D shell reduces the stresses concentrated on the cuts of the structures.

Estimates of Stellar Weak Interaction Rates for Nuclei in the Mass Range A=65-80

NASA Astrophysics Data System (ADS)

Pruet, Jason; Fuller, George M.

2003-11-01

We estimate lepton capture and emission rates, as well as neutrino energy loss rates, for nuclei in the mass range A=65-80. These rates are calculated on a temperature/density grid appropriate for a wide range of astrophysical applications including simulations of late time stellar evolution and X-ray bursts. The basic inputs in our single-particle and empirically inspired model are (i) experimentally measured level information, weak transition matrix elements, and lifetimes, (ii) estimates of matrix elements for allowed experimentally unmeasured transitions based on the systematics of experimentally observed allowed transitions, and (iii) estimates of the centroids of the GT resonances motivated by shell model calculations in the fp shell as well as by (n, p) and (p, n) experiments. Fermi resonances (isobaric analog states) are also included, and it is shown that Fermi transitions dominate the rates for most interesting proton-rich nuclei for which an experimentally determined ground state lifetime is unavailable. For the purposes of comparing our results with more detailed shell model based calculations we also calculate weak rates for nuclei in the mass range A=60-65 for which Langanke & Martinez-Pinedo have provided rates. The typical deviation in the electron capture and β-decay rates for these ~30 nuclei is less than a factor of 2 or 3 for a wide range of temperature and density appropriate for presupernova stellar evolution. We also discuss some subtleties associated with the partition functions used in calculations of stellar weak rates and show that the proper treatment of the partition functions is essential for estimating high-temperature β-decay rates. In particular, we show that partition functions based on unconverged Lanczos calculations can result in errors in estimates of high-temperature β-decay rates.

Adaptive segmentation of nuclei in H&S stained tendon microscopy

NASA Astrophysics Data System (ADS)

Chuang, Bo-I.; Wu, Po-Ting; Hsu, Jian-Han; Jou, I.-Ming; Su, Fong-Chin; Sun, Yung-Nien

2015-12-01

Tendiopathy is a popular clinical issue in recent years. In most cases like trigger finger or tennis elbow, the pathology change can be observed under H and E stained tendon microscopy. However, the qualitative analysis is too subjective and thus the results heavily depend on the observers. We develop an automatic segmentation procedure which segments and counts the nuclei in H and E stained tendon microscopy fast and precisely. This procedure first determines the complexity of images and then segments the nuclei from the image. For the complex images, the proposed method adopts sampling-based thresholding to segment the nuclei. While for the simple images, the Laplacian-based thresholding is employed to re-segment the nuclei more accurately. In the experiments, the proposed method is compared with the experts outlined results. The nuclei number of proposed method is closed to the experts counted, and the processing time of proposed method is much faster than the experts'.

Elucidation of Two Giants: Challenges to Thick-shell Synthesis in CdSe/ZnSe and ZnSe/CdS Core/Shell Quantum Dots

DOE Office of Scientific and Technical Information (OSTI.GOV)

Acharya, Krishna P.; Nguyen, Hue M.; Paulite, Melissa

2015-03-06

Core/thick-shell "giant" quantum dots (gQDs) possessing type II electronic structures exhibit suppressed blinking and diminished nonradiative Auger recombination. Here we investigate CdSe/ZnSe and ZnSe/CdS as potential new gQDs. We show theoretically and experimentally that both can exhibit partial or complete spatial separation of an excited-state electron–hole pair (i.e., type II behavior). However, we reveal that thick-shell growth is challenged by competing processes: alloying and cation exchange. We demonstrate that these can be largely avoided by choice of shelling conditions (e.g., time, temperature, and QD core identity). The resulting CdSe/ZnSe gQDs exhibit unusual single-QD properties, principally emitting from dim gray statesmore » but having high two-exciton (biexciton) emission efficiencies, whereas ZnSe/CdS gQDs show characteristic gQD blinking suppression, though only if shelling is accompanied by partial cation exchange.« less

Phosphine-free synthesis and characterization of type-II ZnSe/CdS core-shell quantum dots

NASA Astrophysics Data System (ADS)

Ghasemzadeh, Roghayyeh; Armanmehr, Mohammad Hasan; Abedi, Mohammad; Fateh, Davood Sadeghi; Bahreini, Zaker

2018-01-01

A phosphine-free route for synthesis of type-II ZnSe/CdS core-shell quantum dots, using green, low cost and environmentally friendly reagents and phosphine-free solvents such as 1-octadecene (ODE) and liquid paraffin has been reported. Hot-injection technique has been used for the synthesis of ZnSe core quantum dots. The CdS shell quantum dots prepared by reaction of CdO precursor and S powder in 1-octadecene (ODE). The ZnSe/CdS core-shell quantum dots were synthesized via successive ion layer adsorption and reaction (SILAR) technique. The characterization of produced quantum dots were performed by absorption and fluorescence spectroscopy, X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM). The results showed the formation of type-II ZnSe/CdS core-shell quantum dots with FWHM 32 nm and uniform size distribution.

Dual origin of pairing in nuclei

NASA Astrophysics Data System (ADS)

Idini, A.; Potel, G.; Barranco, F.; Vigezzi, E.; Broglia, R. A.

2016-11-01

The pairing correlations of the nucleus 120Sn are calculated by solving the Nambu-Gor'kov equations, including medium polarization effects resulting from the interweaving of quasiparticles, spin and density vibrations, taking into account, within the framework of nuclear field theory (NFT), processes leading to self-energy and vertex corrections and to the induced pairing interaction. From these results one can not only demonstrate the inevitability of the dual origin of pairing in nuclei, but also extract information which can be used at profit to quantitatively disentangle the contributions to the pairing gap Δ arising from the bare and from the induced pairing interaction. The first is the strong 1 S 0 short-range NN potential resulting from meson exchange between nucleons moving in time reversal states within an energy range of hundreds of MeV from the Fermi energy. The second results from the exchange of vibrational modes between nucleons moving within few MeV from the Fermi energy. Short- ( v p bare) and long-range ( v p ind) pairing interactions contribute essentially equally to nuclear Cooper pair stability. That is to the breaking of gauge invariance in open-shell superfluid nuclei and thus to the order parameter, namely to the ground state expectation value of the pair creation operator. In other words, to the emergent property of generalized rigidity in gauge space, and associated rotational bands and Cooper pair tunneling between members of these bands.

Isospin symmetry breaking and large-scale shell-model calculations with the Sakurai-Sugiura method

NASA Astrophysics Data System (ADS)

Mizusaki, Takahiro; Kaneko, Kazunari; Sun, Yang; Tazaki, Shigeru

2015-05-01

Recently isospin symmetry breaking for mass 60-70 region has been investigated based on large-scale shell-model calculations in terms of mirror energy differences (MED), Coulomb energy differences (CED) and triplet energy differences (TED). Behind these investigations, we have encountered a subtle problem in numerical calculations for odd-odd N = Z nuclei with large-scale shell-model calculations. Here we focus on how to solve this subtle problem by the Sakurai-Sugiura (SS) method, which has been recently proposed as a new diagonalization method and has been successfully applied to nuclear shell-model calculations.

Enzymatic production of N-acetyl-d-glucosamine from crayfish shell wastes pretreated via high pressure homogenization.

PubMed

Wei, Guoguang; Zhang, Alei; Chen, Kequan; Ouyang, Pingkai

2017-09-01

This study presents an efficient pretreatment of crayfish shell using high pressure homogenization that enables N-acetyl-d-glucosamine (GlcNAc) production by chitinase. Firstly, the chitinase from Serratia proteamaculans NJ303 was screened for its ability to degrade crayfish shell and produce GlcNAc as the sole product. Secondly, high pressure homogenization, which caused the crayfish shell to adopt a fluffy netted structure that was characterized by Scanning electron microscope (SEM), Fourier transform infrared spectrometer (FT-IR), X-ray diffraction (XRD), was evaluated as the best pretreatment method. In addition, the optimal conditions of high pressure homogenization of crayfish shell were determined to be five cycles at a pressure of 400bar, which achieved a yield of 3.9g/L of GlcNAc from 25g/L of crayfish shell in a batch enzymatic reaction over 1.5h. The results showed high pressure homogenization might be an efficient method for direct utilization of crayfish shell for enzymatic production of GlcNAc. Copyright © 2017 Elsevier Ltd. All rights reserved.

Dynamics of a suspension of interacting yolk-shell particles

DOE PAGES

Sánchez Díaz, L. E.; Cortes-Morales, E. C.; Li, X.; ...

2014-12-01

In this work we study the self-diusion properties of a liquid of hollow spherical particles (shells) bearing a smaller solid sphere in their interior (yolks). We model this system using purely repulsive hard-body interactions between all (shell and yolk) particles, but assume the presence of a background ideal solvent such that all the particles execute free Brownian motion between collisions, characterized by short-time self-diusion coecients D0 s for the shells and D0 y for the yolks. Using a softened version of these interparticle potentials we perform Brownian dynamics simulations to determine the mean squared displacement and intermediate scattering function ofmore » the yolk-shell complex. These results can be understood in terms of a set of eective Langevin equations for the N interacting shell particles, pre-averaged over the yolks' degrees of freedom, from which an approximate self-consistent description of the simulated self-diusion properties can be derived. Here we compare the theoretical and simulated results between them, and with the results for the same system in the absence of yolks. We nd that the yolks, which have no eect on the shell-shell static structure, in uence the dynamic properties in a predictable manner, fully captured by the theory.« less

Synergetic Effect of Yolk-Shell Structure and Uniform Mixing of SnS-MoS₂ Nanocrystals for Improved Na-Ion Storage Capabilities.

PubMed

Choi, Seung Ho; Kang, Yun Chan

2015-11-11

Mixed metal sulfide composite microspheres with a yolk-shell structure for sodium-ion batteries are studied. Tin-molybdenum oxide yolk-shell microspheres prepared by a one-pot spray pyrolysis process transform into yolk-shell SnS-MoS2 composite microspheres. The discharge capacities of the yolk-shell and dense-structured SnS-MoS2 composite microspheres for the 100th cycle are 396 and 207 mA h g(-1), and their capacity retentions measured from the second cycle are 89 and 47%, respectively. The yolk-shell SnS-MoS2 composite microspheres with high structural stability during repeated sodium insertion and desertion processes have low charge-transfer resistance even after long-term cycling. The synergetic effect of the yolk-shell structure and uniform mixing of the SnS and MoS2 nanocrystals result in the excellent sodium-ion storage properties of the yolk-shell SnS-MoS2 composite microspheres by improving their structural stability during cycling.

Direct observation of the core/double-shell architecture of intense dual-mode luminescent tetragonal bipyramidal nanophosphors

NASA Astrophysics Data System (ADS)

Kim, Su Yeon; Jeong, Jong Seok; Mkhoyan, K. Andre; Jang, Ho Seong

2016-05-01

Highly efficient downconversion (DC) green-emitting LiYF4:Ce,Tb nanophosphors have been synthesized for bright dual-mode upconversion (UC) and DC green-emitting core/double-shell (C/D-S) nanophosphors--Li(Gd,Y)F4:Yb(18%),Er(2%)/LiYF4:Ce(15%),Tb(15%)/LiYF4--and the C/D-S structure has been proved by extensive scanning transmission electron microscopy (STEM) analysis. Colloidal LiYF4:Ce,Tb nanophosphors with a tetragonal bipyramidal shape are synthesized for the first time and they show intense DC green light via energy transfer from Ce3+ to Tb3+ under illumination with ultraviolet (UV) light. The LiYF4:Ce,Tb nanophosphors show 65 times higher photoluminescence intensity than LiYF4:Tb nanophosphors under illumination with UV light and the LiYF4:Ce,Tb is adapted into a luminescent shell of the tetragonal bipyramidal C/D-S nanophosphors. The formation of the DC shell on the core significantly enhances UC luminescence from the UC core under irradiation of near infrared light and concurrently generates DC luminescence from the core/shell nanophosphors under UV light. Coating with an inert inorganic shell further enhances the UC-DC dual-mode luminescence by suppressing the surface quenching effect. The C/D-S nanophosphors show 3.8% UC quantum efficiency (QE) at 239 W cm-2 and 73.0 +/- 0.1% DC QE. The designed C/D-S architecture in tetragonal bipyramidal nanophosphors is rigorously verified by an energy dispersive X-ray spectroscopy (EDX) analysis, with the assistance of line profile simulation, using an aberration-corrected scanning transmission electron microscope equipped with a high-efficiency EDX. The feasibility of these C/D-S nanophosphors for transparent display devices is also considered.Highly efficient downconversion (DC) green-emitting LiYF4:Ce,Tb nanophosphors have been synthesized for bright dual-mode upconversion (UC) and DC green-emitting core/double-shell (C/D-S) nanophosphors--Li(Gd,Y)F4:Yb(18%),Er(2%)/LiYF4:Ce(15%),Tb(15%)/LiYF4--and the C/D-S structure

7Be(p,gamma)8B S-factor from Ab Initio Wave Functions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Navratil, P; Bertulani, C A; Caurier, E

2006-10-12

There has been a significant progress in ab initio approaches to the structure of light nuclei. Starting from realistic two- and three-nucleon interactions the ab initio no-core shell model (NCSM) predicts low-lying levels in p-shell nuclei. It is a challenging task to extend ab initio methods to describe nuclear reactions. We present here a brief overview of the first steps taken toward nuclear reaction applications. In particular, we discuss our calculation of the {sup 7}Be(p,{gamma}){sup 8}B S-factor. We also present our first results of the {sup 3}He({alpha},{gamma}){sup 7}Be S-factor and of the S-factor of the mirror reaction {sup 3}H({alpha},{gamma}){sup 7}Li.more » The {sup 7}Be(p,{gamma}){sup 8}B and {sup 3}He({alpha},{gamma}){sup 7}Be reactions correspond to the most important uncertainties in solar model predictions of neutrino fluxes.« less

Three-dimensional hierarchical NiCo2O4 nanowire@Ni3S2 nanosheet core/shell arrays for flexible asymmetric supercapacitors

NASA Astrophysics Data System (ADS)

Liu, Bo; Kong, Dezhi; Huang, Zhi Xiang; Mo, Runwei; Wang, Ye; Han, Zhaojun; Cheng, Chuanwei; Yang, Hui Ying

2016-05-01

Three-dimensional (3D) hierarchical NiCo2O4@Ni3S2 core/shell arrays on Ni foam were synthesized by a facile, stepwise synthesis approach. The 3D heterogeneous NiCo2O4 nanostructure forms an interconnected web-like scaffold and serves as the core for the Ni3S2 shell. The as-prepared NiCo2O4@Ni3S2 nanowire array (NWA) electrodes exhibited excellent electrochemical performance, such as high specific areal capacitance and excellent cycling stability. The specific areal capacitance of 3.0 F cm-2 at a current density of 5 mA cm-2 is among the highest values and the only 6.7% capacitance decay after 10 000 cycles demonstrates the excellent cycling stability. A flexible asymmetric supercapacitor (ASC) was fabricated with activated carbon (AC) as the anode and the obtained NiCo2O4@Ni3S2 NWAs as the cathode. The ASC device exhibited a high energy density of 1.89 mW h cm-3 at 5.81 W cm-3 and a high power density of 56.33 W cm-3 at 0.94 mW h cm-3. As a result, the hybrid nanoarchitecture opens a new way to design high performance electrodes for electrochemical energy storage applications.Three-dimensional (3D) hierarchical NiCo2O4@Ni3S2 core/shell arrays on Ni foam were synthesized by a facile, stepwise synthesis approach. The 3D heterogeneous NiCo2O4 nanostructure forms an interconnected web-like scaffold and serves as the core for the Ni3S2 shell. The as-prepared NiCo2O4@Ni3S2 nanowire array (NWA) electrodes exhibited excellent electrochemical performance, such as high specific areal capacitance and excellent cycling stability. The specific areal capacitance of 3.0 F cm-2 at a current density of 5 mA cm-2 is among the highest values and the only 6.7% capacitance decay after 10 000 cycles demonstrates the excellent cycling stability. A flexible asymmetric supercapacitor (ASC) was fabricated with activated carbon (AC) as the anode and the obtained NiCo2O4@Ni3S2 NWAs as the cathode. The ASC device exhibited a high energy density of 1.89 mW h cm-3 at 5.81 W cm-3 and a high power

NIF Double Shell outer/inner shell collision experiments

NASA Astrophysics Data System (ADS)

Merritt, E. C.; Loomis, E. N.; Wilson, D. C.; Cardenas, T.; Montgomery, D. S.; Daughton, W. S.; Dodd, E. S.; Desjardins, T.; Renner, D. B.; Palaniyappan, S.; Batha, S. H.; Khan, S. F.; Smalyuk, V.; Ping, Y.; Amendt, P.; Schoff, M.; Hoppe, M.

2017-10-01

Double shell capsules are a potential low convergence path to substantial alpha-heating and ignition on NIF, since they are predicted to ignite and burn at relatively low temperatures via volume ignition. Current LANL NIF double shell designs consist of a low-Z ablator, low-density foam cushion, and high-Z inner shell with liquid DT fill. Central to the Double Shell concept is kinetic energy transfer from the outer to inner shell via collision. The collision determines maximum energy available for compression and implosion shape of the fuel. We present results of a NIF shape-transfer study: two experiments comparing shape and trajectory of the outer and inner shells at post-collision times. An outer-shell-only target shot measured the no-impact shell conditions, while an `imaging' double shell shot measured shell conditions with impact. The `imaging' target uses a low-Z inner shell and is designed to perform in similar collision physics space to a high-Z double shell but can be radiographed at 16keV, near the viable 2DConA BL energy limit. Work conducted under the auspices of the U.S. DOE by LANL under contract DE-AC52-06NA25396.

Electron Shell as a Resonator

NASA Astrophysics Data System (ADS)

Karpeshin, F. F.

2002-11-01

Main principles of the resonance effect arising in the electron shells in interaction of the nuclei with electromagnetic radiation are analyzed and presented in the historical aspect. Principles of NEET are considered from a more general position, as compared to how this is usually presented. Characteristic features of NEET and its reverse, TEEN, as internal conversion processes are analyzed, and ways are offered of inducing them by laser radiation. The ambivalent role of the Pauli exclusion principles in NEET and TEEN processes is investigated.

Exploring the Physics of Unstable Nuclei

NASA Astrophysics Data System (ADS)

Volya, Alexander

In this presentation the Continuum Shell Model (CSM) approach is advertised as a powerful theoretical tool for studying physics of unstable nuclei. The approach is illustrated using 17O as an example, which is followed by a brief presentation of the general CSM formalism. The successes of the CSM are highlighted and references are provided throughout the text. As an example, the CSM is applied perturbatively to 20O allowing one to explore the effects of continuum on positions of weakly bound states and low-lying resonances, as well as to discern some effects of threshold discontinuity.

Weak interaction probes of light nuclei

NASA Astrophysics Data System (ADS)

Towner, I. S.

1986-03-01

Experimental evidence for pion enhancement in axial charge transitions as predicted by softpion theorems is reviewed. Corrections from non-soft-pion terms seem to be limited. For transitions involving the space part of the axial-vector current, soft-pion theorems are powerless. Meson-exchange currents then involve a complicated interplay among competing process. Explicit calculations in the hard-pion model for closed-shell-plus (or minus)-one nuclei, A=15 and A= =17, are in reasonable agreement with experiment. Quenching in the off-diagonal spin-flip matrix element is larger than in the diagonal matrix element.

Flexible 3D Fe@VO2 core-shell mesh: A highly efficient and easy-recycling catalyst for the removal of organic dyes.

PubMed

Li, Jing; Wang, Ruoqi; Su, Zhen; Zhang, Dandan; Li, Heping; Yan, Youwei

2018-10-01

Nowadays, it is extremely urgent to search for efficient and effective catalysts for water purification due to the severe worldwide water-contamination crises. Here, 3D Fe@VO 2 core-shell mesh, a highly efficient catalyst toward removal of organic dyes with excellent recycling ability in the dark is designed and developed for the first time. This novel core-shell structure is actually 304 stainless steel mesh coated by VO 2 , fabricated by an electrophoretic deposition method. In such a core-shell structure, Fe as the core allows much easier separation from the water, endowing the catalyst with a flexible property for easy recycling, while VO 2 as the shell is highly efficient in degradation of organic dyes with the addition of H 2 O 2 . More intriguingly, the 3D Fe@VO 2 core-shell mesh exhibits favorable performance across a wide pH range. The 3D Fe@VO 2 core-shell mesh can decompose organic dyes both in a light-free condition and under visible irradiation. The possible catalytic oxidation mechanism of Fe@VO 2 /H 2 O 2 system is also proposed in this work. Considering its facile fabrication, remarkable catalytic efficiency across a wide pH range, and easy recycling characteristic, the 3D Fe@VO 2 core-shell mesh is a newly developed high-performance catalyst for addressing the universal water crises. Copyright © 2018 Elsevier B.V. All rights reserved.

Geometrically nonlinear analysis of layered composite plates and shells

NASA Technical Reports Server (NTRS)

Chao, W. C.; Reddy, J. N.

1983-01-01

A degenerated three dimensional finite element, based on the incremental total Lagrangian formulation of a three dimensional layered anisotropic medium was developed. Its use in the geometrically nonlinear, static and dynamic, analysis of layered composite plates and shells is demonstrated. A two dimenisonal finite element based on the Sanders shell theory with the von Karman (nonlinear) strains was developed. It is shown that the deflections obtained by the 2D shell element deviate from those obtained by the more accurate 3D element for deep shells. The 3D degenerated element can be used to model general shells that are not necessarily doubly curved. The 3D degenerated element is computationally more demanding than the 2D shell theory element for a given problem. It is found that the 3D element is an efficient element for the analysis of layered composite plates and shells undergoing large displacements and transient motion.

Ground-state properties of neutron magic nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saxena, G., E-mail: gauravphy@gmail.com; Kaushik, M.

2017-03-15

A systematic study of the ground-state properties of the entire chains of even–even neutron magic nuclei represented by isotones of traditional neutron magic numbers N = 8, 20, 40, 50, 82, and 126 has been carried out using relativistic mean-field plus Bardeen–Cooper–Schrieffer approach. Our present investigation includes deformation, binding energy, two-proton separation energy, single-particle energy, rms radii along with proton and neutron density profiles, etc. Several of these results are compared with the results calculated using nonrelativistic approach (Skyrme–Hartree–Fock method) along with available experimental data and indeed they are found with excellent agreement. In addition, the possible locations of themore » proton and neutron drip-lines, the (Z, N) values for the new shell closures, disappearance of traditional shell closures as suggested by the detailed analyzes of results are also discussed in detail.« less

Neutron capture on short-lived nuclei via the surrogate (d,pγ) reaction

NASA Astrophysics Data System (ADS)

Cizewski, Jolie A.; Ratkiewicz, Andrew

2018-05-01

Rapid r-process nucleosynthesis is responsible for the creation of about half of the elements heavier than iron. Neutron capture on shortlived nuclei in cold processes or during freeze out from hot processes can have a significant impact on the final observed r-process abundances. We are validating the (d,pγ) reaction as a surrogate for neutron capture with measurements on 95Mo targets and a focus on discrete transitions. The experimental results have been analyzed within the Hauser-Feshbach approach with non-elastic breakup of the deuteron providing a neutron to be captured. Preliminary results support the (d,pγ) reaction as a valid surrogate for neutron capture. We are poised to measure the (d,pγ) reaction in inverse kinematics with unstable beams following the development of the experimental techniques.

One-Pot Synthesis of Tunable Crystalline Ni3 S4 @Amorphous MoS2 Core/Shell Nanospheres for High-Performance Supercapacitors.

PubMed

Zhang, Yu; Sun, Wenping; Rui, Xianhong; Li, Bing; Tan, Hui Teng; Guo, Guilue; Madhavi, Srinivasan; Zong, Yun; Yan, Qingyu

2015-08-12

Transition metal sulfides gain much attention as electrode materials for supercapacitors due to their rich redox chemistry and high electrical conductivity. Designing hierarchical nanostructures is an efficient approach to fully utilize merits of each component. In this work, amorphous MoS(2) is firstly demonstrated to show specific capacitance 1.6 times as that of the crystalline counterpart. Then, crystalline core@amorphous shell (Ni(3)S(4)@MoS(2)) is prepared by a facile one-pot process. The diameter of the core and the thickness of the shell can be independently tuned. Taking advantages of flexible protection of amorphous shell and high capacitance of the conductive core, Ni(3)S(4) @amorphous MoS(2) nanospheres are tested as supercapacitor electrodes, which exhibit high specific capacitance of 1440.9 F g(-1) at 2 A g(-1) and a good capacitance retention of 90.7% after 3000 cycles at 10 A g(-1). This design of crystalline core@amorphous shell architecture may open up new strategies for synthesizing promising electrode materials for supercapacitors. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Folding of non-Euclidean curved shells

NASA Astrophysics Data System (ADS)

Bende, Nakul; Evans, Arthur; Innes-Gold, Sarah; Marin, Luis; Cohen, Itai; Santangelo, Christian; Hayward, Ryan

2015-03-01

Origami-based folding of 2D sheets has been of recent interest for a variety of applications ranging from deployable structures to self-folding robots. Though folding of planar sheets follows well-established principles, folding of curved shells involves an added level of complexity due to the inherent influence of curvature on mechanics. In this study, we use principles from differential geometry and thin shell mechanics to establish fundamental rules that govern folding of prototypical creased shells. In particular, we show how the normal curvature of a crease line controls whether the deformation is smooth or discontinuous, and investigate the influence of shell thickness and boundary conditions. We show that snap-folding of shells provides a route to rapid actuation on time-scales dictated by the speed of sound. The simple geometric design principles developed can be applied at any length-scale, offering potential for bio-inspired soft actuators for tunable optics, microfluidics, and robotics. This work was funded by the National Science Foundation through EFRI ODISSEI-1240441 with additional support to S.I.-G. through the UMass MRSEC DMR-0820506 REU program.

Structural and electronic properties of CdSe/ZnS and ZnS/CdSe core/shell nanowires via first principles study

NASA Astrophysics Data System (ADS)

Rehman, Shafiq Ur; Li, H. M.; Ding, Z. J.

2018-05-01

First principles calculations have been performed to predict the structural stability and electronic structures of hydrogen passivated wurtzite CdSe/ZnS and ZnS/CdSe core/shell nanowires (CSNWs) in the [0001] direction. The calculated binding energy shows that ZnS/CdSe CSNWs are more stable than CdSe/ZnS CSNWs and the stability of ZnS/CdSe CSNWs increases with increasing the thickness of ZnS shell. The modulated electronic band gap demonstrates an increase when the size of both CSNWs is reduced, as a result of the quantum confinement effect. The core-to-shell chemical composition of atoms shows that a strong composition effect also exists in these CSNWs, which in turn affects their electronic properties. Our simulated results show that the photoemission spectra of the CSNWs can be significantly improved by tuning the energy gap of CSNWs.

Beta-Decay Rates for Exotic Nuclei and R-Process Nucleosynthesis up to Th and U

NASA Astrophysics Data System (ADS)

Suzuki, Toshio; Yoshida, Takashi; Shibagaki, Shota; Kajino, Toshitaka; Otsuka, Takaharu

Beta-decay rates for exotic nuclei with N = 126 relevant to r-process nucleosynthesis are studied up to Z = 78 by shell-model calculations. The half-lives for the waiting-point nuclei obtained, which are short compared to a standard FRDM, are used to study r-process nucleosynthesis in neutrino-driven winds and magneto-hydrodynamic jets of core-collapse supernova explosions as well as in binary neutron star mergers. The element abundances are obtained up to the third peak as well as beyond the peak region up to thorium and uranium. Thorium and uranium are found to be produced more with the shorter shell-model half-lives and their abundances come closer to the observed values in core-collapse supernova explosions, while in case of binary neutron star mergers they are produced as much as the observed values rather independent of the half-lives.

Asymptotic Giant Branch stars as a source of short-lived radioactive nuclei in the solar nebula

NASA Technical Reports Server (NTRS)

Wasserburg, G. J.; Busso, M.; Gallino, R.; Raiteri, C. M.

1994-01-01

We carried out a theoretical evaluation of the contribution of Asymptotic Giant Branch (AGB) stars to some short-lived (10(exp 6) less than or equal to Tau-bar less than or equal to 2 x 10(exp 7) yr) isotopes in the Interstellar Medium (ISM) and in the early solar system using stellar model calculations for thermally pulsing evolutionary phases of low-mass stars. The yields of s-process nuclei in the convective He-shell for different neutron exposures tau(sub 0) were obtained, and AGB stars were shown to produce several radioactive nuclei (especially Pd-107, Pb-205, Fe-60, Zr-93, Tc-99, Cs-135, and Hf-182) in diferent amounts. Assuming either contamination of the solar nebula from a single AGB star or models for continuous injection and mixing from many stars into the ISM, we calculate the ratios of radioactive to stable nuclei at the epoch of the Sun's formation. The dilution factor between the AGB ejecta and the early solar system matter is obtained by matching the observed Pd-107/Pd-108 and depends on the value of tau(sub 0). It is found that small masses M(sub He) of He-shell material (10(exp -4)-10(exp -7) solar mass) enriched in s-process nuclei are sufficient to contaminate 1 solar mass of the ISM to produce the Pd-107 found in the early solar system. Predictions are made for all of the other radioactive isotopes. The optimal model to explain several observed radioactive species at different states of the proto-solar nebula involves a single AGB star with a low neutron exposure (tau(sub 0) = 0.03 mbarn(sup -1)) which contaminated the cloud with a dilution factor of M(sub He)/solar mass approximately 1.5 x 10(exp -4). This will also contribute newly synthesized stable s-process nuclei in the amount of approximately 10(exp -4) of their abundances already present in the proto-solar cloud. Variations in the degree of homogenization (approximately 30%) of the injected material may account for some of the small general isotopic anomalies found in meteorites. It is

Systematic study of cluster radioactivity of superheavy nuclei

NASA Astrophysics Data System (ADS)

Zhang, Y. L.; Wang, Y. Z.

2018-01-01

The probable cluster radioactivity (CR) of 294118, 296120, and 298122 is studied by using the unified description (UD) formula, universal (UNIV) curve, Horoi formula, and universal decay law (UDL). The predictions by the former three models suggest that the probable emitted clusters are lighter nuclei, and the calculations within the UDL formula give a different prediction: that both the lighter clusters and heavier ones can be emitted from the parent nuclei. A further study on the competition between α decay and CR of Z =104 -124 isotopes is performed. The former three models predict that α decay is the dominant decay mode, but the UDL formula suggests that CR dominates over α decay for Z ≥118 nuclei and the isotopes of 118 292 -296 ,308 -318 , 120 , 284 -304 ,308 -324 and 122-322316 are the most likely candidates as the cluster emitters. Because the former three formulas are just preformation models, the lighter cluster emissions can be described. However, the UDL formula can predict the lighter and heavier CR owing to the inclusion of the preformation and fissionlike mechanisms. Finally, it is found that the shortest CR half-lives are always obtained when the daughter nuclei are around the double magic 208Pb within the UDL formula, which indicates that shell effect has an important influence on CR.

Facile synthesis of mercaptosuccinic acid-capped CdTe/CdS/ZnS core/double shell quantum dots with improved cell viability on different cancer cells and normal cells

NASA Astrophysics Data System (ADS)

Parani, Sundararajan; Bupesh, Giridharan; Manikandan, Elayaperumal; Pandian, Kannaiyan; Oluwafemi, Oluwatobi Samuel

2016-11-01

Water-soluble, mercaptosuccinic acid (MSA)-capped CdTe/CdS/ZnS core/double shell quantum dots (QDs) were prepared by successive growth of CdS and ZnS shells on the as-synthesized CdTe/CdSthin core/shell quantum dots. The formation of core/double shell structured QDs was investigated by ultraviolet-visible (UV-Vis) absorption and photoluminescence (PL) spectroscopy, PL decay studies, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The core/double shell QDs exhibited good photoluminescence quantum yield (PLQY) which is 70% higher than that of the parent core/shell QDs, and they are stable for months. The average particle size of the core/double shell QDs was ˜3 nm as calculated from the transmission electron microscope (TEM) images. The cytotoxicity of the QDs was evaluated on a variety of cancer cells such as HeLa, MCF-7, A549, and normal Vero cells by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) cell viability assay. The results showed that core/double shell QDs were less toxic to the cells when compared to the parent core/shell QDs. MCF-7 cells showed proliferation on incubation with QDs, and this is attributed to the metalloestrogenic activity of cadmium ions released from QDs. The core/double shell CdTe/CdS/ZnS (CSS) QDs were conjugated with transferrin and successfully employed for the biolabeling and fluorescent imaging of HeLa cells. These core/double shell QDs are highly promising fluorescent probe for cancer cell labeling and imaging applications.

Evidence for Ultra-fast Outflows in Radio-quiet Active Galactic Nuclei. II. Detailed Photoionization Modeling of Fe K-shell Absorption Lines

NASA Astrophysics Data System (ADS)

Tombesi, F.; Cappi, M.; Reeves, J. N.; Palumbo, G. G. C.; Braito, V.; Dadina, M.

2011-11-01

X-ray absorption line spectroscopy has recently shown evidence for previously unknown Ultra-fast Outflows (UFOs) in radio-quiet active galactic nuclei (AGNs). These have been detected essentially through blueshifted Fe XXV/XXVI K-shell transitions. In the previous paper of this series we defined UFOs as those highly ionized absorbers with an outflow velocity higher than 10,000 km s-1 and assessed the statistical significance of the associated blueshifted absorption lines in a large sample of 42 local radio-quiet AGNs observed with XMM-Newton. The present paper is an extension of that work. First, we report a detailed curve of growth analysis of the main Fe XXV/XXVI transitions in photoionized plasmas. Then, we estimate an average spectral energy distribution for the sample sources and directly model the Fe K absorbers in the XMM-Newton spectra with the detailed Xstar photoionization code. We confirm that the frequency of sources in the radio-quiet sample showing UFOs is >35% and that the majority of the Fe K absorbers are indeed associated with UFOs. The outflow velocity distribution spans from ~10,000 km s-1 (~0.03c) up to ~100,000 km s-1 (~0.3c), with a peak and mean value of ~42,000 km s-1 (~0.14c). The ionization parameter is very high and in the range log ξ ~ 3-6 erg s-1 cm, with a mean value of log ξ ~ 4.2 erg s-1 cm. The associated column densities are also large, in the range N H ~ 1022-1024 cm-2, with a mean value of N H ~ 1023 cm-2. We discuss and estimate how selection effects, such as those related to the limited instrumental sensitivity at energies above 7 keV, may hamper the detection of even higher velocities and higher ionization absorbers. We argue that, overall, these results point to the presence of extremely ionized and possibly almost Compton-thick outflowing material in the innermost regions of AGNs. This also suggests that UFOs may potentially play a significant role in the expected cosmological feedback from AGNs and their study can

Relativistic Bose-Einstein condensates thin-shell wormholes

NASA Astrophysics Data System (ADS)

Richarte, M. G.; Salako, I. G.; Graça, J. P. Morais; Moradpour, H.; Övgün, Ali

2017-10-01

We construct traversable thin-shell wormholes which are asymptotically Ads/dS applying the cut and paste procedure for the case of an acoustic metric created by a relativistic Bose-Einstein condensate. We examine several definitions of the flare-out condition along with the violation or not of the energy conditions for such relativistic geometries. Under reasonable assumptions about the equation of state of the matter located at the shell, we concentrate on the mechanical stability of wormholes under radial perturbation preserving the original spherical symmetry. To do so, we consider linearized perturbations around static solutions. We obtain that dS acoustic wormholes remain stable under radial perturbations as long as they have small radius; such wormholes with finite radius do not violate the strong/null energy condition. Besides, we show that stable Ads wormhole satisfy some of the energy conditions whereas unstable Ads wormhole with large radii violate them.

2.5D global-disk oscillation models of the Be shell star ζ Tauri. I. Spectroscopic and polarimetric analysis

NASA Astrophysics Data System (ADS)

Escolano, C.; Carciofi, A. C.; Okazaki, A. T.; Rivinius, T.; Baade, D.; Štefl, S.

2015-04-01

Context. A large number of Be stars exhibit intensity variations of their violet and red emission peaks in their H i lines observed in emission. This is the so-called V/R phenomenon, usually explained by the precession of a one-armed spiral density perturbation in the circumstellar disk. That global-disk oscillation scenario was confirmed, both observationally and theoretically, in the previous series of two papers analyzing the Be shell star ζ Tauri. The vertically averaged (2D) global-disk oscillation model used at the time was able to reproduce the V/R variations observed in Hα, as well as the spatially resolved interferometric data from AMBER/VLTI. Unfortunately, that model failed to reproduce the V/R phase of Br15 and the amplitude of the polarization variation, suggesting that the inner disk structure predicted by the model was incorrect. Aims: The first aim of the present paper is to quantify the temporal variations of the shell-line characteristics of ζ Tauri. The second aim is to better understand the physics underlying the V/R phenomenon by modeling the shell-line variations together with the V/R and polarimetric variations. The third aim is to test a new 2.5D disk oscillation model, which solves the set of equations that describe the 3D perturbed disk structure but keeps only the equatorial (i.e., 2D) component of the solution. This approximation was adopted to allow comparisons with the previous 2D model, and as a first step toward a future 3D model. Methods: We carried out an extensive analysis of ζ Tauri's spectroscopic variations by measuring various quantities characterizing its Balmer line profiles: red and violet emission peak intensities (for Hα, Hβ, and Br15), depth and asymmetry of the shell absorption (for Hβ, Hγ, and Hδ), and the respective position (i.e., radial velocity) of each component. We attempted to model the observed variations by implementing in the radiative transfer code HDUST the perturbed disk structure computed with a

The major nucleoside triphosphatase in pea (Pisum sativum L.) nuclei and in rat liver nuclei share common epitopes also present in nuclear lamins

NASA Technical Reports Server (NTRS)

Tong, C. G.; Dauwalder, M.; Clawson, G. A.; Hatem, C. L.; Roux, S. J.

1993-01-01

The major nucleoside triphosphatase (NTPase) activities in mammalian and pea (Pisum sativum L.) nuclei are associated with enzymes that are very similar both biochemically and immunochemically. The major NTPase from rat liver nuclei appears to be a 46-kD enzyme that represents the N-terminal portion of lamins A and C, two lamina proteins that apparently arise from the same gene by alternate splicing. Monoclonal antibody (MAb) G2, raised to human lamin C, both immunoprecipitates the major (47 kD) NTPase in pea nuclei and recognizes it in western blot analyses. A polyclonal antibody preparation raised to the 47-kD pea NTPase (pc480) reacts with the same lamin bands that are recognized by MAb G2 in mammalian nuclei. The pc480 antibodies also bind to the same lamin-like bands in pea nuclear envelope-matrix preparations that are recognized by G2 and three other MAbs known to bind to mammalian lamins. In immunofluorescence assays, pc480 and anti-lamin antibodies stain both cytoplasmic and nuclear antigens in plant cells, with slightly enhanced staining along the periphery of the nuclei. These results indicate that the pea and rat liver NTPases are structurally similar and that, in pea nuclei as in rat liver nuclei, the major NTPase is probably derived from a lamin precursor by proteolysis.

Nuclear mass formula with the shell energies obtained by a new method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koura, H.; Tachibana, T.; Yamada, M.

1998-12-21

Nuclear shapes and masses are estimated by a new method. The main feature of this method lies in estimating shell energies of deformed nuclei from spherical shell energies by mixing them with appropriate weights. The spherical shell energies are calculated from single-particle potentials, and, till now, two mass formulas have been constructed from two different sets of potential parameters. The standard deviation of the calculated masses from all the experimental masses of the 1995 Mass Evaluation is about 760 keV. Contrary to the mass formula by Tachibana, Uno, Yamada and Yamada in the 1987-1988 Atomic Mass Predictions, the present formulasmore » can give nuclear shapes and predict on super-heavy elements.« less

Exploring the effect of band alignment and surface states on photoinduced electron transfer from CuInS2/CdS core/shell quantum dots to TiO2 electrodes.

PubMed

Sun, Mingye; Zhu, Dehua; Ji, Wenyu; Jing, Pengtao; Wang, Xiuying; Xiang, Weidong; Zhao, Jialong

2013-12-11

Photoinduced electron transfer (ET) processes from CuInS2/CdS core/shell quantum dots (QDs) with different core sizes and shell thicknesses to TiO2 electrodes were investigated by time-resolved photoluminescence (PL) spectroscopy. The ET rates and efficiencies from CuInS2/CdS QDs to TiO2 were superior to those of CuInS2/ZnS QDs. An enhanced ET efficiency was surprisingly observed for 2.0 nm CuInS2 core QDs after growth of the CdS shell. On the basis of the experimental and theoretical analysis, the improved performances of CuInS2/CdS QDs were attributed to the passivation of nonradiative traps by overcoating shell and enhanced delocalization of electron wave function from core to CdS shell due to lower conduction band offset. These results indicated that the electron distribution regulated by the band alignment between core and shell of QDs and the passivation of surface defect states could improve ET performance between donor and acceptor.

Dual origin of pairing in nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Idini, A.; Potel, G.; Barranco, F.

The pairing correlations of the nucleus {sup 120}Sn are calculated by solving the Nambu–Gor’kov equations, including medium polarization effects resulting from the interweaving of quasiparticles, spin and density vibrations, taking into account, within the framework of nuclear field theory (NFT), processes leading to self-energy and vertex corrections and to the induced pairing interaction. From these results one can not only demonstrate the inevitability of the dual origin of pairing in nuclei, but also extract information which can be used at profit to quantitatively disentangle the contributions to the pairing gap Δ arising from the bare and from the induced pairingmore » interaction. The first is the strong {sup 1}S{sub 0} short-range NN potential resulting from meson exchange between nucleons moving in time reversal states within an energy range of hundreds of MeV from the Fermi energy. The second results from the exchange of vibrational modes between nucleons moving within few MeV from the Fermi energy. Short- (v{sub p}{sup bare}) and long-range (v{sub p}{sup ind}) pairing interactions contribute essentially equally to nuclear Cooper pair stability. That is to the breaking of gauge invariance in open-shell superfluid nuclei and thus to the order parameter, namely to the ground state expectation value of the pair creation operator. In other words, to the emergent property of generalized rigidity in gauge space, and associated rotational bands and Cooper pair tunneling between members of these bands.« less

β-decay Rates for Exotic Nuclei and r-process Nucleosynthesis up to Thorium and Uranium

NASA Astrophysics Data System (ADS)

Suzuki, Toshio; Shibagaki, Shota; Yoshida, Takashi; Kajino, Toshitaka; Otsuka, Takaharu

2018-06-01

Beta-decay rates for exotic nuclei with neutron magic number of N = 126 relevant to r-process nucleosynthesis are studied up to Z = 78 by shell-model calculations. The half-lives for the waiting-point nuclei obtained, which are short compared to a standard finite-range-droplet model, are used to study r-process nucleosynthesis in core-collapse supernova (CCSN) explosions and binary neutron star mergers. The element abundances are obtained up to the third peak as well as beyond the peak region up to thorium and uranium. The position of the third peak is found to be shifted toward a higher mass region in both CCSN explosions and neutron star mergers. We find that thorium and uranium elements are produced more with the shorter shell-model half-lives and their abundances come close to the observed values in CCSN explosions. In the case of binary neutron star mergers, thorium and uranium are produced consistently with the observed values independent of the half-lives.

Epitaxial Growth of Lattice-Mismatched Core-Shell TiO2 @MoS2 for Enhanced Lithium-Ion Storage.

PubMed

Dai, Rui; Zhang, Anqi; Pan, Zhichang; Al-Enizi, Abdullah M; Elzatahry, Ahmed A; Hu, Linfeng; Zheng, Gengfeng

2016-05-01

Core-shell structured nanohybrids are currently of significant interest due to their synergetic properties and enhanced performances. However, the restriction of lattice mismatch remains a severe obstacle for heterogrowth of various core-shells with two distinct crystal structures. Herein, a controlled synthesis of lattice-mismatched core-shell TiO2 @MoS2 nano-onion heterostructures is successfully developed, using unilamellar Ti0.87 O2 nanosheets as the starting material and the subsequent epitaxial growth of MoS2 on TiO2 . The formation of these core-shell nano-onions is attributed to an amorphous layer-induced heterogrowth mechanism. The number of MoS2 layers can be well tuned from few to over ten layers, enabling layer-dependent synergistic effects. The core-shell TiO2 @MoS2 nano-onion heterostructures exhibit significantly enhanced energy storage performance as lithium-ion battery anodes. The approach has also been extended to other lattice-mismatched systems such as TiO2 @MoSe2 , thus suggesting a new strategy for the growth of well-designed lattice-mismatched core-shell structures. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fabrication and characterization of ZnS/ZnO core shell nanostructures on silver wires

NASA Astrophysics Data System (ADS)

Kao, Chyuan Haur; Su, Wei Ming; Li, Cheng Yuan; Weng, Wei Chih; Weng, Chen Yuan; Cheng, Chin-Chi; Lin, Yung-Sen; Lin, Chia Feng; Chen, Hsiang

2018-06-01

In this research, ZnS nanoparticles were synthesized on ZnO/silver wires to form ZnS/ZnO core shell structures. Various outward appearance and colors could be observed by different ZnO growth and sulfurization conditions. To evaluate the properties of these nanostructures, optical properties and chemical bindings were analyzed by photoluminescence, Raman analysis, and X-ray photoelectron spectroscopy. Furthermore, material characterizations including transmission electron microscopy and X-ray diffraction confirmed that cubic ZnS (311)/ZnO nanostructures were grown on silver wires for the first time. ZnS/ZnO core shell structures on silver wires are promising for future optoelectronic and biomedical applications.

Driving gas shells with radiation pressure on dust in radiation-hydrodynamic simulations

NASA Astrophysics Data System (ADS)

Costa, Tiago; Rosdahl, Joakim; Sijacki, Debora; Haehnelt, Martin G.

2018-01-01

We present radiation-hydrodynamic simulations of radiatively-driven gas shells launched by bright active galactic nuclei (AGN) in isolated dark matter haloes. Our goals are (1) to investigate the ability of AGN radiation pressure on dust to launch galactic outflows and (2) to constrain the efficiency of infrared (IR) multiscattering in boosting outflow acceleration. Our simulations are performed with the radiation-hydrodynamic code RAMSES-RT and include both single- and multiscattered radiation pressure from an AGN, radiative cooling and self-gravity. Since outflowing shells always eventually become transparent to the incident radiation field, outflows that sweep up all intervening gas are likely to remain gravitationally bound to their halo even at high AGN luminosities. The expansion of outflowing shells is well described by simple analytic models as long as the shells are mildly optically thick to IR radiation. In this case, an enhancement in the acceleration of shells through IR multiscattering occurs as predicted, i.e. a force \\dot{P} ≈ τ_IR L/c is exerted on the gas. For high optical depths τIR ≳ 50, however, momentum transfer between outflowing optically thick gas and IR radiation is rapidly suppressed, even if the radiation is efficiently confined. At high τIR, the characteristic flow time becomes shorter than the required trapping time of IR radiation such that the momentum flux \\dot{P} ≪ τ_IR L/c. We argue that while unlikely to unbind massive galactic gaseous haloes, AGN radiation pressure on dust could play an important role in regulating star formation and black hole accretion in the nuclei of massive compact galaxies at high redshift.

Synthesis, Decay Properties, and Identification of Superheavy Nuclei Produced in 48Ca-induced Reactions

NASA Astrophysics Data System (ADS)

Oganessian, Yu. Ts.; Utyonkov, V. K.; Lobanov, Yu. V.; Abdullin, F. Sh.; Polyakov, A. N.; Sagaidak, R. N.; Shirokovsky, I. V.; Tsyganov, Yu. S.; Voinov, A. A.; Iliev, S.; Subbotin, V. G.; Sukhov, A. M.; Gulbekian, G. G.; Bogomolov, S. L.; Gikal, B. N.; Mezentsev, A. N.; Subotic, K.; Zagrebaev, V. I.; Itkis, M. G.; Moody, K. J.; Henderson, R. A.; Patin, J. B.; Shaughnessy, D. A.; Stoyer, M. A.; Stoyer, N. J.; Wilk, P. A.; Kenneally, J. M.; Landrum, J. H.; Wild, J. F.; Lougheed, R. W.

2007-10-01

Thirty-four new nuclides with Z = 104-116, 118 and N = 161-177 have been synthesized in the complete-fusion reactions of 238U, 237Np, 242,244Pu, 243Am, 245,248Cm, and 249Cf targets with 48Ca beams. The masses of evaporation residues were identified through measurements of the excitation functions of the xn-evaporation channels and from cross bombardments. The decay properties of the new nuclei agree with those of previously known heavy nuclei and with predictions from different theoretical models. A discussion of self-consistent interpretations of all observed decay chains originating from the parent isotopes 282,283112, 282113, 286-289114, 287,288115, 290-293116, and 294118 is presented. Decay energies and lifetimes of the neutron-rich superheavy nuclei as well as their production cross sections indicate a considerable increase in the stability of nuclei with the approach to the theoretically predicted nuclear shells with N = 184 and Z = 114.

Synthesis, Decay Properties, and Identification of Superheavy Nuclei Produced in 48CA-INDUCED Reactions

NASA Astrophysics Data System (ADS)

Oganessian, Yu. Ts.; Utyonkov, V. K.; Lobanov, Yu. V.; Abdullin, F. Sh.; Polyakov, A. N.; Sagaidak, R. N.; Shirokovsky, I. V.; Tsyganov, Yu. S.; Voinov, A. A.; Iliev, S.; Subbotin, V. G.; Sukhov, A. M.; Gulbekian, G. G.; Bogomolov, S. L.; Gikal, B. N.; Mezentsev, A. N.; Subotic, K.; Zagrebaev, V. I.; Itkis, M. G.; Moody, K. J.; Henderson, R. A.; Patin, J. B.; Shaughnessy, D. A.; Stoyer, M. A.; Stoyer, N. J.; Wilk, P. A.; Kenneally, J. M.; Landrum, J. H.; Wild, J. F.; Lougheed, R. W.

2008-04-01

Thirty-four new nuclides with Z = 104-116, 118 and N = 161-177 have been synthesized in the complete-fusion reactions of 238U, 237Np, 242,244Pu, 243Am, 245,248Cm, and 249Cf targets with 48Ca beams. The masses of evaporation residues were identified through measurements of the excitation functions of the xn-evaporation channels and from cross bombardments. The decay properties of the new nuclei agree with those of previously known heavy nuclei and with predictions from different theoretical models. A discussion of self-consistent interpretations of all observed decay chains originating from the parent isotopes 282,283112, 282113, 286-289114, 287,288115, 290-293116, and 294118 is presented. Decay energies and lifetimes of the neutron-rich superheavy nuclei as well as their production cross sections indicate a considerable increase in the stability of nuclei with the approach to the theoretically predicted nuclear shells with N = 184 and Z = 114.

Theoretical study of triaxial shapes of neutron-rich Mo and Ru nuclei

DOE PAGES

Zhang, C. L.; Bhat, G. H.; Nazarewicz, W.; ...

2015-09-10

Here, whether atomic nuclei can possess triaxial shapes at their ground states is still a subject of ongoing debate. According to theory, good prospects for low-spin triaxiality are in the neutron-rich Mo-Ru region. Recently, transition quadrupole moments in rotational bands of even-mass neutron-rich isotopes of molybdenum and ruthenium nuclei have been measured. The new data have provided a challenge for theoretical descriptions invoking stable triaxial deformations. The purpose of this study is to understand experimental data on rotational bands in the neutron-rich Mo-Ru region, we carried out theoretical analysis of moments of inertia, shapes, and transition quadrupole moments of neutron-richmore » even-even nuclei around 110Ru using self-consistent mean-field and shell model techniques. Methods: To describe yrast structures in Mo and Ru isotopes, we use nuclear density functional theory (DFT) with the optimized energy density functional UNEDF0. We also apply triaxial projected shell model (TPSM) to describe yrast and positive-parity, near-yrast band structures. As a result, our self-consistent DFT calculations predict triaxial ground-state deformations in 106,108Mo and 108,110,112Ru and reproduce the observed low-frequency behavior of moments of inertia. As the rotational frequency increases, a negative-gamma structure, associated with the aligned ν(h 11/2) 2 pair, becomes energetically favored. The computed transition quadrupole moments vary with angular momentum, which reflects deformation changes with rotation; those variations are consistent with experiment. The TPSM calculations explain the observed band structures assuming stable triaxial shapes. Lastly, the structure of neutron-rich even-even nuclei around Ru-110 is consistent with triaxial shape deformations. Our DFT and TPSM frameworks provide a consistent and complementary description of experimental data.« less

Ultrathin TiO2 layer coated-CdS spheres core-shell nanocomposite with enhanced visible-light photoactivity.

PubMed

Chen, Zhang; Xu, Yi-Jun

2013-12-26

Development of various strategies for controllable fabrication of core-shell nanocomposites (CSNs) with highly active photocatalytic performance has been attracting ever-increasing research attention. In particular, control of the ultrathin layer TiO2 shell in constructing CSNs in an aqueous phase is a significant but technologically challenging issue. Here, this paper demonstrates the interface assembly synthesis of CdS nanospheres@TiO2 core-shell photocatalyst via the electrostatic interaction of negatively charged water-stable titania precursor with positively charged CdS nanospheres (CdS NSPs), followed by the formation of the ultrathin-layer TiO2 shell through a facile refluxing process in aqueous phase. The as-formed CdS NSPs@TiO2 core-shell nanohybrid exhibits a high visible-light-driven photoactivity for selective transformation and reduction of heavy metal ions. The ultrathin TiO2 layer coated on CdS NSPs results in excellent light transmission property, enhanced adsorption capacity, and improved transfer of charge carriers and lifespan of photoinduced electron-hole pairs, which would prominently contribute to the significant photoactivity enhancement. It is anticipated that this facile aqueous-phase synthesis strategy could be extended to design a variety of more efficient CSN photocatalysts with controllable morphology toward target applications in diverse photoredox processes.

Core-shell structure of Miglyol/poly(D,L-lactide)/Poloxamer nanocapsules studied by small-angle neutron scattering.

PubMed

Rübe, Andrea; Hause, Gerd; Mäder, Karsten; Kohlbrecher, Joachim

2005-10-03

The contrast variation technique in small angle neutron scattering (SANS) was used to investigate the inner structure of nanocapsules on the example of poly(D,L-lactide) (PLA) nanocapsules. The determination of the PLA and Poloxamer shell thickness was the focus of this study. Highest sensitivity on the inner structure of the nanocapsules was obtained when the scattering length density of the solvent was varied between the one of the Miglyol core and the PLA shell. According to the fit data the PLA shell thickness was 9.8 nm. The z-averaged radius determined by SANS experiments correlated well with dynamic light scattering (DLS) results, although DLS values were systematically slightly higher than the ones measured by SANS. This could be explained by taking into account the influence of Poloxamer attached to the nanocapsules surface. For a refined fit model with a second shell consisting of Poloxamer, SANS values and DLS values fitted well with each other. The characterization method presented here is significant because detailed insights into the nanocapsule and the Poloxamer shell were gained for the first time. This method could be used to develop strategies for the optimization of the shell properties concerning controlled release and to study changes in the shell structure during degradation processes.

PREFACE: New nuclear structure phenomena in the vicinity of closed shells

NASA Astrophysics Data System (ADS)

Johnson, A.; Wyss, R.

1995-01-01

The proceedings of the international symposium on "New Nuclear Structure Phenomena in the Vicinity of Closed Shells - SELMA 94", held in Stockholm, Uppsala and on the Baltic Sea from Aug. 30 - Sep. 3 are collected in this volume. Since almost 40% of the session time was kept open for discussions, it is difficult to give full justice to the character of the meeting in a written report. However, since also many posters are presented in this volume, we hope that some of the flavour of this lively symposium will pass onto the reader. We have chosen to group related contributions in order to facilitate the reading. Several articles, though, may fit into several categories. With the event of large detector arrays there has been a tremendous development in the field of nuclear spectroscopy. The discovery of super-deformation has been followed by detailed spectroscopy in the second well. Hence, the concept of shell closure is reinterpreted in general terms, involving shapes different from spherical. Close to the drip lines, we expect new shells and new structure effects to emerge. Loosely bound neutrons may form a new state of nuclear matter. The regions of the nuclear chart far from the line of stability can be explored in the future by means of radioactive ion beams. New structure effects, that one might encounter far from the line of stability was one of the themes of this conference. The strong impact of the nuclear shell model is also evident in other branches of physics, like the structure of metal-clusters. Special attention was paid to the Sn-isotopes. In the Sn-isotopic chain, spectroscopic measurements are extending beyond the doubly-magic nucleus 132Sn. Large efforts have recently been made to study nuclei in the vicinity of the doubly-magic nucleus 100Sn, the other extreme end of the chain. Spectroscopic data on 100Sn would open the entire shell for nuclear structure studies, ranging over a number of 32 neutrons. During the organization of this meeting, the

Alternative Storage Environments for Shelled Peanuts.

USDA-ARS?s Scientific Manuscript database

Alternative Storage Environments for Shelled Peanuts. C. L. BUTTS1, K. HORM2, S. POWELL3, B. ANTHONY2, J. BENNETT2, D. COWART3, and M.C. LAMB1. 1USDA, ARS, National Peanut Research Laboratory, Dawson, GA, 2Mars Chocolate NA, Elizabethtown, PA,3 Birdsong Peanuts, Blakely, GA Small chamber studies w...

Time-resolved photoluminescence study of CdSe/CdMnS/CdS core/multi-shell nanoplatelets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murphy, J. R.; Department of Physics, State University of New York, University at Buffalo, Buffalo, New York 14260; Delikanli, S.

2016-06-13

We used photoluminescence spectroscopy to resolve two emission features in CdSe/CdMnS/CdS and CdSe/CdS core/multi-shell nanoplatelet heterostructures. The photoluminescence from the magnetic sample has a positive circular polarization with a maximum centered at the position of the lower energy feature. The higher energy feature has a corresponding signature in the absorption spectrum; this is not the case for the low-energy feature. We have also studied the temporal evolution of these features using a pulsed-excitation/time-resolved photoluminescence technique to investigate their corresponding recombination channels. A model was used to analyze the temporal dynamics of the photoluminescence which yielded two distinct timescales associated withmore » these recombination channels. The above results indicate that the low-energy feature is associated with recombination of electrons with holes localized at the core/shell interfaces; the high-energy feature, on the other hand, is excitonic in nature with the holes confined within the CdSe cores.« less

Is seniority a partial dynamic symmetry in the first νg9/2 shell?

NASA Astrophysics Data System (ADS)

Morales, A. I.; Benzoni, G.; Watanabe, H.; de Angelis, G.; Nishimura, S.; Coraggio, L.; Gargano, A.; Itaco, N.; Otsuka, T.; Tsunoda, Y.; Van Isacker, P.; Browne, F.; Daido, R.; Doornenbal, P.; Fang, Y.; Lorusso, G.; Patel, Z.; Rice, S.; Sinclair, L.; Söderström, P.-A.; Sumikama, T.; Valiente-Dobón, J. J.; Wu, J.; Xu, Z. Y.; Yagi, A.; Yokoyama, R.; Baba, H.; Avigo, R.; Bello Garrote, F. L.; Blasi, N.; Bracco, A.; Bruce, A. M.; Camera, F.; Ceruti, S.; Crespi, F. C. L.; Delattre, M.-C.; Dombradi, Zs.; Gottardo, A.; Isobe, T.; Kojouharov, I.; Kurz, N.; Kuti, I.; Lalkovski, S.; Matsui, K.; Melon, B.; Mengoni, D.; Miyazaki, T.; Modamio-Hoybjor, V.; Momiyama, S.; Napoli, D. R.; Niikura, M.; Orlandi, R.; Podolyák, Zs.; Regan, P. H.; Sakurai, H.; Sahin, E.; Sohler, D.; Schaffner, H.; Taniuchi, R.; Taprogge, J.; Vajta, Zs.; Wieland, O.; Yalcinkaya, M.

2018-06-01

The low-lying structures of the midshell νg9/2 Ni isotopes 72Ni and 74Ni have been investigated at the RIBF facility in RIKEN within the EURICA collaboration. Previously unobserved low-lying states were accessed for the first time following β decay of the mother nuclei 72Co and 74Co. As a result, we provide a complete picture in terms of the seniority scheme up to the first (8+) levels for both nuclei. The experimental results are compared to shell-model calculations in order to define to what extent the seniority quantum number is preserved in the first neutron g9/2 shell. We find that the disappearance of the seniority isomerism in the (81+) states can be explained by a lowering of the seniority-four (6+) levels as predicted years ago. For 74Ni, the internal de-excitation pattern of the newly observed (62+) state supports a restoration of the normal seniority ordering up to spin J = 4. This property, unexplained by the shell-model calculations, is in agreement with a dominance of the single-particle spherical regime near 78Ni.

Energy transfer in aggregated CuInS2/ZnS core-shell quantum dots deposited as solid films

NASA Astrophysics Data System (ADS)

Gardelis, S.; Fakis, M.; Droseros, N.; Georgiadou, D.; Travlos, A.; Nassiopoulou, A. G.

2017-01-01

We report on the morphology and optical properties of CuInS2/ZnS core-shell quantum dots in solid films by means of AFM, SEM, HRTEM, steady state and time-resolved photoluminescence (PL) spectroscopy. The amount of aggregation of the CuInS2/ZnS QDs was controlled by changing the preparation conditions of the films. A red-shift of the PL spectrum of CuInS2/ZnS core-shell quantum dots, deposited as solid films on silicon substrates, is observed upon increasing the amount of aggregation. The presence of larger aggregates was found to lead to a larger PL red-shift. Besides, as the degree of aggregation increased, the PL decay became slower. We attribute the observed PL red-shift to energy transfer from the smaller to the larger dots within the aggregates, with the emission being realized via a long decay recombination mechanism (100-200 ns), the origin of which is discussed.

Strongly luminescent InP/ZnS core-shell nanoparticles.

PubMed

Haubold, S; Haase, M; Kornowski, A; Weller, H

2001-05-18

The wide-bandgap semiconducting material, zinc sulfide, has been coated on indium phosphide nanoclusters to a 1-2-Å thickness. The resulting InP-ZnS core-shell particle (as shown in the TEM image; scale 1 cm=5 nm) exhibits bright luminescence at room temperature with quantum efficiencies as high as 23 %. © 2001 WILEY-VCH Verlag GmbH, Weinheim, Fed. Rep. of Germany.

Two-nucleon high-spin states, the Bansal-French model and the crude shell model

NASA Astrophysics Data System (ADS)

Chan, Tsan Ung

1987-08-01

Recent data on two-nucleon stretched high-spin states agree well with the crude shell model predictions. For two-neutron high-spin states, the A and T linear dependence of B2n in the Bansal-French model can be deduced from the A and T linear dependence of Bn and the crude shell model. 7-2 states in some Zn and Ge even nuclei might be two-proton states. This hypothesis should be confirmed by two-proton transfer reaction.

Beta-decay strength and isospin mixing studies in the sd and fp-shells

NASA Astrophysics Data System (ADS)

Jokinen, A.; ńystö, J.; Dendooven, P.; Honkanen, A.; Lipas, P.; Peräjärvi, K.; Oinonen, M.; Siiskonen, T.

1998-12-01

We have studied beta decays of MT<0 nuclei in sd and fp shells. The decay of 41Ti shows a large, 10(8) %, isospin mixing of IAS and the Gamow-Teller strength is observed to be quenched by a factor of q2=0.64. These results can be reproduced qualitatively in our shell model calculations. We have observed for the first time proton and gamma decay of the isobaric analogue state in 23Mg. Our results on the isospin mixing of the isobaric analogue state agrees well with the shell model calculations. The obtained proton branch of the IAS is used to extract the transition strength for the reaction 22Na(p,γ)23Mg.

A Modular Implementation for the Simulation of 1D and 2D Solid-State NMR Spectra of Quadrupolar Nuclei in the Virtual Multifrequency Spectrometer-Draw Graphical Interface.

PubMed

Presti, Davide; Pedone, Alfonso; Licari, Daniele; Barone, Vincenzo

2017-05-09

We present the implementation of the solid state (SoS)NMR module for the simulation of several 1D and 2D NMR spectra of all the elements in the periodic table in the virtual multifrequency spectrometer (VMS). This module is fully integrated with the graphical user interface of VMS (VMS-Draw) [Licari et al., J. Comput. Chem. 36, 2015, 321-334], a freeware tool which allows a user-friendly handling of structures and analyses of advanced spectroscopical properties of chemical compounds-from model systems to real-world applications. Besides the numerous modules already available in VMS for the study of electronic, optical, vibrational, vibronic, and EPR properties, here the simulation of NMR spectra is presented with a particular emphasis on those techniques usually employed to investigate solid state systems. The SoSNMR module benefits from its ability to work under both periodic and nonperiodic conditions, such that small molecules/molecular clusters can be treated, as well as extended three-dimensional systems enforcing (or not) translational periodicity. These features allow VMS to simulate spectra resulting from NMR calculations by some popular quantum chemistry codes, namely Gaussian09/16, Castep, and Quantum Espresso. The effectiveness of the SoSNMR module of VMS is examined throughout the manuscript, and applied to simulate 1D static, MAS, and VAS NMR spectra as well as 2D correlation (90°, MAS) and MQMAS spectra of active NMR nuclei embedded in different amorphous and crystalline systems of actual interest in chemistry and material science. Finally, the program is able to simulate the spectra of both the total ensemble of spin-active nuclei present in the system and of subensembles differentiated depending on the chemical environment of the first and second coordination sphere in a very general way applicable to any kind of systems.

Au/ZnS core/shell nanocrystals as an efficient anode photocatalyst in direct methanol fuel cells.

PubMed

Chen, Wei-Ta; Lin, Yin-Kai; Yang, Ting-Ting; Pu, Ying-Chih; Hsu, Yung-Jung

2013-10-04

Au/ZnS core/shell nanocrystals with controllable shell thicknesses were synthesized using a cysteine-assisted hydrothermal method. Incorporating Au/ZnS nanocrystals into the traditional Pt-catalyzed half-cell reaction led to a 43.3% increase in methanol oxidation current under light illumination, demonstrating their promising potential for metal/semiconductor hybrid nanocrystals as the anode photocatalyst in direct methanol fuel cells.

Construction of CdS@UIO-66-NH2 core-shell nanorods for enhanced photocatalytic activity with excellent photostability.

PubMed

Liang, Qian; Cui, Sainan; Liu, Changhai; Xu, Song; Yao, Chao; Li, Zhongyu

2018-08-15

A novel class of CdS@UIO-66-NH 2 core shell heterojunction was fabricated by the facile in-situ solvothermal method. Characterizations show that porous UIO-66-NH 2 shell not only allows the visible light to be absorbed on CdS nanorod core, but also provides abundant catalytic active sites as well as an intimate heterojunction interface between UIO-66-NH 2 shell and CdS nanorod core. By taking advantage of this property, the core-shell composite presents highly solar-driven photocatalytic performance compared with pristine UIO-66-NH 2 and CdS nanorod for the degradation of organic dyes including malachite green (MG) and methyl orange (MO), and displays superior photostability after four recycles. Furthermore, the photoelectrochemical performance of CdS@UIO-66-NH 2 can be measured by the UV-vis spectra, Mott-Schottky plots and photocurrent. The remarkably enhanced photocatalytic activity of CdS@UIO-66-NH 2 can be ascribed to high surface areas, intimate interaction on molecular scale and the formation of one-dimensional heterojunction with n-n type. What's more, the core-shell heterostructural CdS@UIO-66-NH 2 can facilitate the effective separation and transfer of the photoinduced interfacial electron-hole pairs and protect CdS nanorod core from photocorrosion. Copyright © 2018 Elsevier Inc. All rights reserved.

Interplay between proton-neutron pairing and deformation in self-conjugated medium mass nuclei

NASA Astrophysics Data System (ADS)

Gambacurta, Danilo; Lacroix, Denis

2016-05-01

We employ a model combining self-consistent mean-field and shell model techniques to study the competition between particle-like and proton-neutron pairing correlations in fp-shell even-even self-conjugate nuclei. Deformation effects are realistically and microscopically described. The resulting approach can give a precise description of pairing correlations and eventually treat the coexistence of different condensate formed of pairs with different total spin/ isospin. The standard BCS calculations are systematically compared with approaches including correlation effects beyond the independent quasi-particle picture. The competition between proton-neutron correlations in the isoscalar and isovector channels is also analyzed, as well as their dependence on the deformation properties.

A core–shell electrode for dynamically and statically stable Li–S battery chemistry

DOE PAGES

Chung, Sheng-Heng; Chang, Chi-Hao; Manthiram, Arumugam

2016-08-17

Sulfur is an appealing cathode material for establishing advanced lithium batteries as it offers a high theoretical capacity of 1675 mA h g -1 at low material and operating costs. However, the lithium–sulfur (Li–S) electrochemical cells face several formidable challenges arising from both the materials chemistry (e.g., low electrochemical utilization of sulfur and severe polysulfide diffusion) and battery chemistry (e.g., dynamic and static instability and low sulfur loadings). Here in this study, we present the design of a core–shell cathode with a pure sulfur core shielded within a conductive shell-shaped electrode. The new electrode configuration allows Li–S cells to loadmore » with a high amount of sulfur (sulfur loadings of up to 30 mg cm -2 and sulfur content approaching 70 wt%). The core–shell cathodes demonstrate a superior dynamic and static electrochemical stability in Li–S cells. The high-loading cathodes exhibit (i) a high sulfur utilization of up to 97% at C/20–C/2 rates and (ii) a low self-discharge during long-term cell storage for a three-month rest period and at different cell-storage conditions. Finally, a polysulfide-trap cell configuration is designed to evidence the eliminations of polysulfide diffusion and to investigate the relationship between the electrode configuration and electrochemical characteristics. Finally, the comprehensive analytical results based on the high-loading cathodes suggest that (i) the core–shell cathode is a promising solution for designing highly reversible Li–S cells and (ii) the polysulfide-trap cell configuration is a viable approach to qualitatively evaluating the presence or absence of polysulfide diffusion.« less

Influence of dimensionality and interface type on optical and electronic properties of CdS/ZnS core-shell nanocrystals—A first-principles study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kocevski, V., E-mail: vancho.vk@gmail.com, E-mail: vancho.kocevski@physics.uu.se; Eriksson, O.; Gerard, C.

2015-10-28

Semiconducting nanocrystals (NCs) have become one of the leading materials in a variety of applications, mainly due to their size tunable band gap and high intensity emission. Their photoluminescence (PL) properties can be notably improved by capping the nanocrystals with a shell of another semiconductor, making core-shell structures. We focus our study on the CdS/ZnS core-shell nanocrystals that are closely related to extensively studied CdSe/CdS NCs, albeit exhibiting rather different photoluminescence properties. We employ density functional theory to investigate the changes in the electronic and optical properties of these nanocrystals with size, core/shell ratio, and interface structure between the coremore » and the shell. We have found that both the lowest unoccupied eigenstate (LUES) and the highest occupied eigenstate (HOES) wavefunction (WF) are localized in the core of the NCs, with the distribution of the LUES WF being more sensitive to the size and the core/shell ratio. We show that the radiative lifetimes are increasing, and the Coulomb interaction energies decrease with increasing NC size. Furthermore, we investigated the electronic and optical properties of the NCs with different interfaces between the core and the shell and different core types. We find that the different interfaces and core types have rather small influence on the band gaps and the absorption indexes, as well as on the confinement of the HOES and LUES WFs. Also the radiative lifetimes are found to be only slightly influenced by the different structural models. In addition, we compare these results with the previous results for CdSe/CdS NCs, reflecting the different PL properties of these two types of NCs. We argue that the difference in their Coulomb interaction energies is one of the main reasons for their distinct PL properties.« less

Interacting shells in AdS spacetime and chaos

NASA Astrophysics Data System (ADS)

Brito, Richard; Cardoso, Vitor; Rocha, Jorge V.

2016-07-01

We study the simplest two-body problem in asymptotically anti-de Sitter spacetime: two, infinitely thin, concentric spherical shells of matter. We include only gravitational interaction between the two shells, but we show that the dynamics of this system is highly nontrivial. We observe prompt collapse to a black hole, delayed collapse and even perpetual oscillatory motion, depending on the initial location of the shells (or their energy content). The system exhibits critical behavior, and we show strong hints that it is also chaotic.

Studies of Heavy-Ion Reactions and Transuranic Nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schroeder, W. Udo

2016-07-28

Studies of heavy-ion reactions and transuranic nuclei performed by the University of Rochester Nuclear Science Research Group have been successful in furthering experimental systematics and theoretical understanding of the behavior of nuclear systems excited to their limits of stability. The theoretical results explain specifically the “boiling” and “vaporization” of atomic nuclei, but are more generally applicable to isolated, quantal many-particle systems which, under thermal or mechanical stresses, all disintegrate by evaporation, via surface cluster emission, or via fission-like processes. Accompanying experimental investigations by the group have demonstrated several new types of dynamical instability of nuclei: In central, “head-on” collisions, targetmore » nuclei exhibit limited ability to stop energetic projectile nuclei and to dissipate the imparted linear momentum. Substantial matter overlap (“neck”) between projectile and target nuclei, which is observed at elevated collision energies, can be stretched considerably and break at several places simultaneously. These results provide new testing grounds for microscopic theory of the cohesion of nuclear matter. This property has remained elusive, even though the elementary nucleon-nucleon forces are well known since some time. Technical R&D has resulted in a detailed characterization of a novel plastic material, which can now be used in the design of sensitive diagnostic systems for various types of radio-activity. Innovative application of powerful laser systems has produced intense, controllable sources of exotic particle radioactivity for nuclear investigations. Several students have received their Ph.D. degree in experimental nuclear science for their work on basic nuclear research or R&D projects.« less

Enhanced oxidation stability of quasi core-shell alloyed CdSeS quantum dots prepared through aqueous microwave synthesis technique.

PubMed

Zhan, Hong-Ju; Zhou, Pei-Jiang; Ma, Rong; Liu, Xi-Jing; He, Yu-Ning; Zhou, Chuan-Yun

2014-01-01

Quasi core shell alloyed CdSeS quantum dots (QDs) have been prepared through a facile aqueous-phase route employing microwave irradiation technique. The optical spectroscopy and structure characterization evidenced the quasi core shell alloyed structures of CdSeS QDs. The X-ray diffraction patterns of the obtained CdSeS QDs displayed peak positions very close to those of bulk cubic CdS crystal structures and the result of X-ray photoelectron spectroscopy data re-confirmed the thick CdS shell on the CdSe core. The TEM images and HRTEM images of the CdSeS QDs ascertained the well-defined spherical particles and a relatively narrow size distribution. On the basis, the stability of the obtained QDs in an oxidative environment was also discussed using etching reaction by H2O2. The experiments result showed the as-prepared QDs present high tolerance towards H2O2, obviously superior to the commonly used CdTe QDs and core-shell CdTe/CdS QDs, which was attributed to the unique quasi core-shell CdSeS crystal structure and the small lattice mismatch between CdSe and CdS semiconductor materials. This assay provided insight to obtain high stable crystal structured semiconductor nanocrystals in the design and synthesis process.

Surface properties of neutron-rich exotic nuclei within relativistic mean field formalisms

NASA Astrophysics Data System (ADS)

Bhuyan, M.; Carlson, B. V.; Patra, S. K.; Zhou, Shan-Gui

2018-02-01

In this theoretical study, we establish a correlation between the neutron skin thickness and the nuclear symmetry energy for the even-even isotopes of Fe, Ni, Zn, Ge, Se, and Kr within the framework of the axially deformed self-consistent relativistic mean field for the nonlinear NL 3* and density-dependent DD-ME1 interactions. The coherent density functional method is used to formulate the symmetry energy, the neutron pressure, and the curvature of finite nuclei as a function of the nuclear radius. We have performed broad studies for the mass dependence on the symmetry energy in terms of the neutron-proton asymmetry for mass 70 ≤A ≤96 . From this analysis, we found a notable signature of a shell closure at N =50 in the isotopic chains of Fe, Ni, Zn, Ge, Se, and Kr nuclei. The present study reveals a interrelationship between the characteristics of infinite nuclear matter and the neutron skin thickness of finite nuclei.

Swimming of a Sea Butterfly with an Elongated Shell

NASA Astrophysics Data System (ADS)

Karakas, Ferhat; Maas, Amy E.; Murphy, David W.

2017-11-01

Sea butterflies (pteropods) are small, zooplanktonic marine snails which swim by flapping highly flexible parapodia. Previous studies show that the swimming hydrodynamics of Limacina helicina, a polar pteropod with a spiraled shell, is similar to tiny insect flight aerodynamics and that forward-backward pitching is key for lift generation. However, swimming by diverse pteropod species with different shell shapes has not been examined. We present measurements of the swimming of Cuvierina columnella, a warm water species with an elongated non-spiraled shell collected off the coast of Bermuda. With a body length of 9 mm, wing beat frequency of 4-6 Hz and swimming speed of 35 mm/s, these organisms swim at a Reynolds number of approximately 300, larger than that of L. helicina. High speed 3D kinematics acquired via two orthogonal cameras reveals that the elongated shell correlates with reduced body pitching and that the wings bend approximately 180 degrees in each direction, overlapping at the end of each half-stroke. Time resolved 2D flow measurements collected with a micro-PIV system reveal leading edge vortices present in both power and recovery strokes. Interactions between the overlapping wings and the shell also likely play a role in lift generation.

Role of N-methyl-2-pyrrolidone for preparation of Fe3O4@SiO2 controlled the shell thickness

NASA Astrophysics Data System (ADS)

Wee, Sung-Bok; Oh, Hyeon-Cheol; Kim, Tae-Gyun; An, Gye-Seok; Choi, Sung-Churl

2017-04-01

We developed a simple and novel approach for the synthesis of Fe3O4@SiO2 nanoparticles with controlled shell thickness, and studied the mechanism. The introduction of N-methyl-2-pyrrolidone (NMP) led to trapping of monomer nuclei in single shell and controlled the shell thickness. Fe3O4@SiO2 controlled the shell thickness, showing a high magnetization value (64.47 emu/g). Our results reveal the role and change in the chemical structure of NMP during the core-shell synthesis process. NMP decomposed to 4-aminobutanoic acid in alkaline condition and decreased the hydrolysis rate of the silica coating process.

Segmentation of whole cells and cell nuclei from 3-D optical microscope images using dynamic programming.

PubMed

McCullough, D P; Gudla, P R; Harris, B S; Collins, J A; Meaburn, K J; Nakaya, M A; Yamaguchi, T P; Misteli, T; Lockett, S J

2008-05-01

Communications between cells in large part drive tissue development and function, as well as disease-related processes such as tumorigenesis. Understanding the mechanistic bases of these processes necessitates quantifying specific molecules in adjacent cells or cell nuclei of intact tissue. However, a major restriction on such analyses is the lack of an efficient method that correctly segments each object (cell or nucleus) from 3-D images of an intact tissue specimen. We report a highly reliable and accurate semi-automatic algorithmic method for segmenting fluorescence-labeled cells or nuclei from 3-D tissue images. Segmentation begins with semi-automatic, 2-D object delineation in a user-selected plane, using dynamic programming (DP) to locate the border with an accumulated intensity per unit length greater that any other possible border around the same object. Then the two surfaces of the object in planes above and below the selected plane are found using an algorithm that combines DP and combinatorial searching. Following segmentation, any perceived errors can be interactively corrected. Segmentation accuracy is not significantly affected by intermittent labeling of object surfaces, diffuse surfaces, or spurious signals away from surfaces. The unique strength of the segmentation method was demonstrated on a variety of biological tissue samples where all cells, including irregularly shaped cells, were accurately segmented based on visual inspection.

Highly Luminescent Water-Dispersible NIR-Emitting Wurtzite CuInS2/ZnS Core/Shell Colloidal Quantum Dots

PubMed Central

2017-01-01

Copper indium sulfide (CIS) quantum dots (QDs) are attractive as labels for biomedical imaging, since they have large absorption coefficients across a broad spectral range, size- and composition-tunable photoluminescence from the visible to the near-infrared, and low toxicity. However, the application of NIR-emitting CIS QDs is still hindered by large size and shape dispersions and low photoluminescence quantum yields (PLQYs). In this work, we develop an efficient pathway to synthesize highly luminescent NIR-emitting wurtzite CIS/ZnS QDs, starting from template Cu2-xS nanocrystals (NCs), which are converted by topotactic partial Cu+ for In3+ exchange into CIS NCs. These NCs are subsequently used as cores for the overgrowth of ZnS shells (≤1 nm thick). The CIS/ZnS core/shell QDs exhibit PL tunability from the first to the second NIR window (750–1100 nm), with PLQYs ranging from 75% (at 820 nm) to 25% (at 1050 nm), and can be readily transferred to water upon exchange of the native ligands for mercaptoundecanoic acid. The resulting water-dispersible CIS/ZnS QDs possess good colloidal stability over at least 6 months and PLQYs ranging from 39% (at 820 nm) to 6% (at 1050 nm). These PLQYs are superior to those of commonly available water-soluble NIR-fluorophores (dyes and QDs), making the hydrophilic CIS/ZnS QDs developed in this work promising candidates for further application as NIR emitters in bioimaging. The hydrophobic CIS/ZnS QDs obtained immediately after the ZnS shelling are also attractive as fluorophores in luminescent solar concentrators. PMID:28638177

Placental Volumetry by 2-D Sonography with a New Mathematical Formula: Prospective Study on the Shell of a Spherical Sector Model.

PubMed

Kozinszky, Zoltan; Surányi, Andrea; Péics, Hajnalka; Molnár, András; Pál, Attila

2015-08-01

The aim of this study was to determine the utility of a new mathematical model in volumetric assessment of the placenta using 2-D ultrasound. Placental volumetry was performed in a prospective cross-sectional survey by virtual organ computer-aided analysis (VOCAL) with the help of a shell-off method in 346 uncomplicated pregnancies according to STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) guidelines. Furthermore, placental thickness, length and height were measured with the 2-D technique to estimate placental volume based on the mathematical formula for the volume of "the shell of the spherical sector." Fetal size was also assessed by 2-D sonography. The placental volumes measured by 2-D and 3-D techniques had a correlation of 0.86. In the first trimester, the correlation was 0.82, and later during pregnancy, it was 0.86. Placental volumetry using "the circle-shaped shell of the spherical sector" mathematical model with 2-D ultrasound technique may be introduced into everyday practice to screen for placental volume deviations associated with adverse pregnancy outcome. Copyright © 2015 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Neutron-antineutron oscillations in nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dover, C.B.; Gal, A.; Richard, J.M.

1983-03-01

We present calculations of the neutron-antineutron (n-n-bar) annihilation lifetime T in deuterium, /sup 16/O, and /sup 56/Fe in terms of the free-space oscillation time tau/sub n/n-bar. The coupled Schroedinger equations for the n and n-bar wave functions in a nucleus are solved numerically, using a realistic shell-model potential which fits the empirical binding energies of the neu- p tron orbits, and a complex n-bar-nucleus optical potential obtained from fits to p-bar-atom level shifts. Most previous estimates of T in nuclei, which exhibit large variations, are found to be quite inaccurate. When the nuclear-physics aspects of the problem are handled properlymore » (in particular, the finite neutron binding, the nuclear radius, and the surface diffuseness), the results are found to be rather stable with respect to allowable changes in the parameters of the nuclear model. We conclude that experimental limits on T in nuclei can be used to give reasonably precise constraints on tau/sub n/n-bar: T>10/sup 30/ or 10/sup 31/ yr leads to tau/sub n/n-bar>(1.5--2) x 10/sup 7/ or (5--6) x 10/sup 7/ sec, respectively.« less

Two-nucleon high-spin states, the Bansal-French model and the crude shell model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chan, T.U.

Recent data on two-nucleon stretched high-spin states agree well with the crude shell model predictions. For two-neutron high-spin states, the A and T linear dependence of B/sub 2n/ in the Bansal-French model can be deduced from the A and T linear dependence of B/sub n/ and the crude shell model. 7/sub 2//sup -/ states in some Zn and Ge even nuclei might be two-proton states. This hypothesis should be confirmed by two-proton transfer reaction.

Neutrino-Induced Nucleosynthesis in Helium Shells of Early Core-Collapse Supernovae

NASA Astrophysics Data System (ADS)

Banerjee, Projjwal; Qian, Yong-Zhong; Heger, Alexander; Haxton, Wick

2016-02-01

We summarize our studies on neutrino-driven nucleosynthesis in He shells of early core-collapse supernovae with metallicities of Z ≲ 10-3 Z⊙. We find that for progenitors of ˜ 11-15 M⊙, the neutrons released by 4He(ν¯ee, e+n)3H in He shells can be captured to produce nuclei with mass numbers up to A ˜ 200. This mechanism is sensitive to neutrino emission spectra and flavor oscillations. In addition, we find two new primary mechanisms for neutrino-induced production of 9Be in He shells. The first mechanism produces 9Be via 7Li(n,γ)8Li(n,γ)9Li(e- ν¯ee)9Be and relies on a low explosion energy for its survival. The second mechanism operates in progenitors of ˜ 8 M⊙, where 9Be can be produced directly via 7Li(3H, n0)9Be during the rapid expansion of the shocked Heshell material. The light nuclei 7Li and 3H involved in these mechanisms are produced by neutrino interactions with 4He. We discuss the implications of neutrino-induced nucleosynthesis in He shells for interpreting the elemental abundances in metal-poor stars.

Electronic structure and intersubband magnetoabsorption spectra of CdSe/CdS core-shell nanowires

NASA Astrophysics Data System (ADS)

Xiong, Wen

2016-10-01

The electronic structures of CdSe/CdS core-shell nanowires are calculated based on the effective-mass theory, and it is found that the hole states in CdSe/CdS core-shell nanowires are strongly mixed, which are very different from the hole states in CdSe or CdS nanowires. In addition, we find the three highest hole states at the Γ point are almost localized in the CdSe core and the energies of the hole states in CdSe/CdS core-shell nanowires can be enhanced greatly when the core radius Rc increases and the total radius R is fixed. The degenerate hole states are split by the magnetic field, and the split energies will increase when |Jh | increases from 1/2 to 7/2, while they are almost not influenced by the change of the core radius Rc. The absorption spectra of CdSe/CdS core-shell nanowires at the Γ point are also studied in the magnetic field when the temperature T is considered, and we find there are only two peaks will arise if the core radius Rc and the temperature T increase. The intensity of each optical absorption can be considerably enhanced by increasing the core radius Rc when the temperature T is fixed, it is due to the increase of their optical transition matrix element. Meanwhile, the intensity of each optical absorption can be decreased when the temperature T increases and the core radius Rc is fixed, and this is because the Fermi-Dirac distribution function of the corresponding hole states will increase as the increase of the temperature T.

Facile consecutive solvothermal growth of highly fluorescent InP/ZnS core/shell quantum dots using a safer phosphorus source.

PubMed

Byun, Ho-June; Song, Woo-Seuk; Yang, Heesun

2011-06-10

The work presents a facile, stepwise synthetic approach for the production of highly fluorescent InP/ZnS core/shell quantum dots (QDs) by using a safer phosphorus (P) precursor. First, InP quantum dots (QDs) were solvothermally prepared at 180 °C for 24 h by using a P source of P(N(CH(3))(2))(3). The as-grown InP QDs were consecutively placed in another solvothermal condition for ZnS shell overcoating. In contrast to the almost non-fluorescent InP QDs, due to their highly defective surface states, the ZnS-coated InP QDs were highly fluorescent as a result of effective surface passivation. After the shell growth, the resulting InP/ZnS core/shell QDs were subjected to a size-sorting processing, by which red- to green-emitting QDs with quantum yields (QYs) of 24-60% were produced. Solvothermal shell growth parameters such as the reaction time and Zn/In solution concentration ratio were varied and optimized toward the highest QYs of core/shell QDs.

Facile consecutive solvothermal growth of highly fluorescent InP/ZnS core/shell quantum dots using a safer phosphorus source

NASA Astrophysics Data System (ADS)

Byun, Ho-June; Song, Woo-Seuk; Yang, Heesun

2011-06-01

The work presents a facile, stepwise synthetic approach for the production of highly fluorescent InP/ZnS core/shell quantum dots (QDs) by using a safer phosphorus (P) precursor. First, InP quantum dots (QDs) were solvothermally prepared at 180 °C for 24 h by using a P source of P(N(CH3)2)3. The as-grown InP QDs were consecutively placed in another solvothermal condition for ZnS shell overcoating. In contrast to the almost non-fluorescent InP QDs, due to their highly defective surface states, the ZnS-coated InP QDs were highly fluorescent as a result of effective surface passivation. After the shell growth, the resulting InP/ZnS core/shell QDs were subjected to a size-sorting processing, by which red- to green-emitting QDs with quantum yields (QYs) of 24-60% were produced. Solvothermal shell growth parameters such as the reaction time and Zn/In solution concentration ratio were varied and optimized toward the highest QYs of core/shell QDs.

Similarity-transformed dyson mapping and SDG-interacting boson hamiltonian

NASA Astrophysics Data System (ADS)

Navrátil, P.; Dobeš, J.

1991-10-01

The sdg-interacting boson hamiltonian is constructed from the fermion shell-model input. The seniority boson mapping as given by the similarity-transformed Dyson boson mapping is used. The s, d, and g collective boson amplitudes are determined consistently from the mapped hamiltonian. Influence of the starting shell-model parameters is discussed. Calculations for the Sm isotopic chain and for the 148Sm, 150Nd, and 196Pt nuclei are presented. Calculated energy levels as well as E2 and E4 properties agree rather well with experimental ones. To obtain such agreement, the input shell-model parameters cannot be fixed at a constant set for several nuclei but have to be somewhat varied, especially in the deformed region. Possible reasons for this variation are discussed. Effects of the explicit g-boson consideration are shown.

Cluster shell model: I. Structure of 9Be, 9B

NASA Astrophysics Data System (ADS)

Della Rocca, V.; Iachello, F.

2018-05-01

We calculate energy spectra, electromagnetic transition rates, longitudinal and transverse electron scattering form factors and log ft values for beta decay in 9Be, 9B, within the framework of a cluster shell model. By comparing with experimental data, we find strong evidence for the structure of these nuclei to be two α-particles in a dumbbell configuration with Z2 symmetry, plus an additional nucleon.

Ground states of larger nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pieper, S.C.; Wiringa, R.B.; Pandharipande, V.R.

1995-08-01

The methods used for the few-body nuclei require operations on the complete spin-isospin vector; the size of this vector makes such methods impractical for nuclei with A > 8. During the last few years we developed cluster expansion methods that do not require operations on the complete vector. We use the same Hamiltonians as for the few-body nuclei and variational wave functions of form similar to the few-body wave functions. The cluster expansions are made for the noncentral parts of the wave functions and for the operators whose expectation values are being evaluated. The central pair correlations in the wavemore » functions are treated exactly and this requires the evaluation of 3A-dimensional integrals which are done with Monte Carlo techniques. Most of our effort was on {sup 16}O, other p-shell nuclei, and {sup 40}Ca. In 1993 the Mathematics and Computer Science Division acquired a 128-processor IBM SP which has a theoretical peak speed of 16 Gigaflops (GFLOPS). We converted our program to run on this machine. Because of the large memory on each node of the SP, it was easy to convert the program to parallel form with very low communication overhead. Considerably more effort was needed to restructure the program from one oriented towards long vectors for the Cray computers at NERSC to one that makes efficient use of the cache of the RS6000 architecture. The SP made possible complete five-body cluster calculations of {sup 16}O for the first time; previously we could only do four-body cluster calculations. These calculations show that the expectation value of the two-body potential is converging less rapidly than we had thought, while that of the three-body potential is more rapidly convergent; the net result is no significant change to our predicted binding energy for {sup 16}O using the new Argonne v{sub 18} potential and the Urbana IX three-nucleon potential. This result is in good agreement with experiment.« less

Nuclear tetrahedral symmetry: possibly present throughout the periodic table.

PubMed

Dudek, J; Goźdź, A; Schunck, N; Miśkiewicz, M

2002-06-24

More than half a century after the fundamental, spherical shell structure in nuclei had been established, theoretical predictions indicated that the shell gaps comparable or even stronger than those at spherical shapes may exist. Group-theoretical analysis supported by realistic mean-field calculations indicate that the corresponding nuclei are characterized by the TD(d) ("double-tetrahedral") symmetry group. Strong shell-gap structure is enhanced by the existence of the four-dimensional irreducible representations of TD(d); it can be seen as a geometrical effect that does not depend on a particular realization of the mean field. Possibilities of discovering the TD(d) symmetry in experiment are discussed.

Facile morphology-controlled synthesis of nickel-coated graphite core-shell particles for excellent conducting performance of polymer-matrix composites and enhanced catalytic reduction of 4-nitrophenol

NASA Astrophysics Data System (ADS)

Bian, Juan; Lan, Fang; Wang, Yilong; Ren, Ke; Zhao, Suling; Li, Wei; Chen, Zhihong; Li, Jiangyu; Guan, Jianguo

2018-04-01

We have developed a novel seed-mediated growth method to fabricate nickel-coated graphite composite particles (GP@Ni-CPs) with controllable shell morphology by simply adjusting the concentration of sodium hydroxide ([NaOH]). The fabrication of two kinds of typical GP@Ni-CPs includes adsorption of Ni2+ via electrostatic attraction, sufficient heterogeneous nucleation of Ni atoms by an in situ reduction, and shell-controlled growth by regulating the kinetics of electroless Ni plating in turn. High [NaOH] results in fast kinetics of electroless plating, which causes heterogeneous nuclei to grow isotropically. After fast and uniform growth of Ni nuclei, GP@Ni-CPs with dense shells can be achieved. The first typical GP@Ni-CPs exhibit denser shells, smaller diameters and higher conductivities than the available commercial ones, indicating their important applications in the conducting of polymer-matrix composites. On the other hand, low [NaOH] favors slow kinetics. Thus, the reduction rate of Ni2+ slows down to a relatively low level so that electroless plating is dominated thermodynamically instead of kinetically, leading to an anisotropic crystalline growth of nuclei and finally to the formation of GP@Ni-CPs with nanoneedle-like shells. The second typical samples can effectively catalyze the reduction of p-nitrophenol into p-aminophenol with NaBH4 in comparison with commercial GP@Ni-CPs and RANEY® Ni, owing to the strong charge accumulation effect of needle-like Ni shells. This work proposes a model system for fundamental investigations and has important applications in the fields of electronic interconnection and catalysis.

Structure and density of cometary nuclei

NASA Astrophysics Data System (ADS)

Weissman, Paul R.; Lowry, Stephen C.

2008-09-01

Understanding the nature of the cometary nucleus remains one of the major problems in solar system science. Whipple’s (1950) icy conglomerate model has been very successful at explaining a range of cometary phenomena, including the source of cometary activity and the nongravitational orbital motion of the nuclei. However, the internal structure of the nuclei is still largely unknown. We review herein the evidence for cometary nuclei as fluffy aggregates or primordial rubble piles, as first proposed by Donn et al. (1985) and Weissman (1986). These models assume that cometary nuclei are weakly bonded aggregations of smaller, icy- onglomerate planetesimals, possibly held together only by self-gravity. Evidence for this model comes from studies of the accretion and subsequent evolution of material in the solar nebula, from observations of disrupted comets, and in particular comet Shoemaker-Levy 9, from measurements of the ensemble rotational properties of observed cometary nuclei, and from recent spacecraft missions to comets. Although the evidence for rubble pile nuclei is growing, the eventual answer to this question will likely not come until we can place a spacecraft in orbit around a cometary nucleus and study it in detail over many months to years. ESA’s Rosetta mission, now en route to comet 67P/Churyumov- Gerasimenko, will provide that opportunity.

Synthesis, characterization, and 3D-FDTD simulation of Ag@SiO2 nanoparticles for shell-isolated nanoparticle-enhanced Raman spectroscopy.

PubMed

Uzayisenga, Viviane; Lin, Xiao-Dong; Li, Li-Mei; Anema, Jason R; Yang, Zhi-Lin; Huang, Yi-Fan; Lin, Hai-Xin; Li, Song-Bo; Li, Jian-Feng; Tian, Zhong-Qun

2012-06-19

Au-seed Ag-growth nanoparticles of controllable diameter (50-100 nm), and having an ultrathin SiO(2) shell of controllable thickness (2-3 nm), were prepared for shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS). Their morphological, optical, and material properties were characterized; and their potential for use as a versatile Raman signal amplifier was investigated experimentally using pyridine as a probe molecule and theoretically by the three-dimensional finite-difference time-domain (3D-FDTD) method. We show that a SiO(2) shell as thin as 2 nm can be synthesized pinhole-free on the Ag surface of a nanoparticle, which then becomes the core. The dielectric SiO(2) shell serves to isolate the Raman-signal enhancing core and prevent it from interfering with the system under study. The SiO(2) shell also hinders oxidation of the Ag surface and nanoparticle aggregation. It significantly improves the stability and reproducibility of surface-enhanced Raman scattering (SERS) signal intensity, which is essential for SERS applications. Our 3D-FDTD simulations show that Ag-core SHINERS nanoparticles yield at least 2 orders of magnitude greater enhancement than Au-core ones when excited with green light on a smooth Ag surface, and thus add to the versatility of our SHINERS method.

Inner-shell photodetachment of transition metal negative ions

NASA Astrophysics Data System (ADS)

Dumitriu, Ileana

This thesis focuses on the study of inner-shell photodetachment of transition metal negative ions, specifically Fe- and Ru- . Experimental investigations have been performed with the aim of gaining new insights into the physics of negative atomic ions and providing valuable absolute cross section data for astrophysics. The experiments were performed using the X-ray radiation from the Advanced Light Source, Lawrence Berkeley National Laboratory, and the merged-beam technique for photoion spectroscopy. Negative ions are a special class of atomic systems very different from neutral atoms and positive ions. The fundamental physics of the interaction of transition metal negative ions with photons is interesting but difficult to analyze in detail because the angular momentum coupling generates a large number of possible terms resulting from the open d shell. Our work reports on the first inner-shell photodetachment studies and absolute cross section measurements for Fe- and Ru -. In the case of Fe-, an important astrophysical abundant element, the inner-shell photodetachment cross section was obtained by measuring the Fe+ and Fe2+ ion production over the photon energy range of 48--72 eV. The absolute cross sections for the production of Fe+ and Fe2+ were measured at four photon energies. Strong shape resonances due to the 3p→3d photoexcitation were measured above the 3p detachment threshold. The production of Ru+, Ru2+, and Ru3+ from Ru- was measured over 30--90 eV photon energy range The absolute photodetachment cross sections of Ru - ([Kr] 4d75s 2) leading to Ru+, Ru2+, and Ru 3+ ion production were measured at three photon energies. Resonance effects were observed due to interference between transitions of the 4 p-electrons to the quasi-bound 4p54d85s 2 states and the 4d→epsilonf continuum. The role of many-particle effects, intershell interaction, and polarization seems much more significant in Ru- than in Fe- photodetachment.

Investigation of the particle-core structure of odd-mass nuclei in the NpNn scheme

NASA Astrophysics Data System (ADS)

Bucurescu, D.; Cata, G.; Cutoiu, D.; Dragulescu, E.; Ivasu, M.; Zamfir, N. V.; Gizon, A.; Gizon, J.

1989-10-01

The NpNn scheme is applied to data related to collective band structures determined by the unique parity shell model orbitals in odd-A nuclei from the mass regions A≌80-100 and A≌130. Simple systematics are obtained which give a synthetic picture of the evolution of the particle-core coupling in these nuclear regions.

3D image display of fetal ultrasonic images by thin shell

NASA Astrophysics Data System (ADS)

Wang, Shyh-Roei; Sun, Yung-Nien; Chang, Fong-Ming; Jiang, Ching-Fen

1999-05-01

Due to the properties of convenience and non-invasion, ultrasound has become an essential tool for diagnosis of fetal abnormality during women pregnancy in obstetrics. However, the 'noisy and blurry' nature of ultrasound data makes the rendering of the data a challenge in comparison with MRI and CT images. In spite of the speckle noise, the unwanted objects usually occlude the target to be observed. In this paper, we proposed a new system that can effectively depress the speckle noise, extract the target object, and clearly render the 3D fetal image in almost real-time from 3D ultrasound image data. The system is based on a deformable model that detects contours of the object according to the local image feature of ultrasound. Besides, in order to accelerate rendering speed, a thin shell is defined to separate the observed organ from unrelated structures depending on those detected contours. In this way, we can support quick 3D display of ultrasound, and the efficient visualization of 3D fetal ultrasound thus becomes possible.

The nuclear contacts and short range correlations in nuclei

NASA Astrophysics Data System (ADS)

Weiss, R.; Cruz-Torres, R.; Barnea, N.; Piasetzky, E.; Hen, O.

2018-05-01

Atomic nuclei are complex strongly interacting systems and their exact theoretical description is a long-standing challenge. An approximate description of nuclei can be achieved by separating its short and long range structure. This separation of scales stands at the heart of the nuclear shell model and effective field theories that describe the long-range structure of the nucleus using a mean-field approximation. We present here an effective description of the complementary short-range structure using contact terms and stylized two-body asymptotic wave functions. The possibility to extract the nuclear contacts from experimental data is presented. Regions in the two-body momentum distribution dominated by high-momentum, close-proximity, nucleon pairs are identified and compared to experimental data. The amount of short-range correlated (SRC) nucleon pairs is determined and compared to measurements. Non-combinatorial isospin symmetry for SRC pairs is identified. The obtained one-body momentum distributions indicate dominance of SRC pairs above the nuclear Fermi-momentum.

Polypyrrole shell@3D-Ni metal core structured electrodes for high-performance supercapacitors.

PubMed

Chen, Gao-Feng; Su, Yu-Zhi; Kuang, Pan-Yong; Liu, Zhao-Qing; Chen, Dao-Yi; Wu, Xu; Li, Nan; Qiao, Shi-Zhang

2015-03-16

Three-dimensional (3D) nanometal films serving as current collectors have attracted much interest recently owing to their promising application in high-performance supercapacitors. In the process of the electrochemical reaction, the 3D structure can provide a short diffusion path for fast ion transport, and the highly conductive nanometal may serve as a backbone for facile electron transfer. In this work, a novel polypyrrole (PPy) shell@3D-Ni-core composite is developed to enhance the electrochemical performance of conventional PPy. With the introduction of a Ni metal core, the as-prepared material exhibits a high specific capacitance (726 F g(-1) at a charge/discharge rate of 1 A g(-1)), good rate capability (a decay of 33% in Csp with charge/discharge rates increasing from 1 to 20 A g(-1)), and high cycle stability (only a small decrease of 4.2% in Csp after 1000 cycles at a scan rate of 100 mV s(-1)). Furthermore, an aqueous symmetric supercapacitor device is fabricated by using the as-prepared composite as electrodes; the device demonstrates a high energy density (≈21.2 Wh kg(-1)) and superior long-term cycle ability (only 4.4% and 18.6% loss in Csp after 2000 and 5000 cycles, respectively). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cell cycle S phase markers are expressed in cerebral neuron nuclei of cats infected by the Feline Panleukopenia Virus.

PubMed

Poncelet, Luc; Garigliany, Mutien; Ando, Kunie; Franssen, Mathieu; Desmecht, Daniel; Brion, Jean-Pierre

2016-12-16

The cell cycle-associated neuronal death hypothesis, which has been proposed as a common mechanism for most neurodegenerative diseases, is notably supported by evidencing cell cycle effectors in neurons. However, in naturally occurring nervous system diseases, these markers are not expressed in neuron nuclei but in cytoplasmic compartments. In other respects, the Feline Panleukopenia Virus (FPV) is able to complete its cycle in mature brain neurons in the feline species. As a parvovirus, the FPV is strictly dependent on its host cell reaching the cell cycle S phase to start its multiplication. In this retrospective study on the whole brain of 12 cats with naturally-occurring, FPV-associated cerebellar atrophy, VP2 capsid protein expression was detected by immunostaining not only in some brain neuronal nuclei but also in neuronal cytoplasm in 2 cats, suggesting that viral mRNA translation was still occurring. In these cats, double immunostainings demonstrated the expression of cell cycle S phase markers cyclin A, cdk2 and PCNA in neuronal nuclei. Parvoviruses are able to maintain their host cells in S phase by triggering the DNA damage response. S139 phospho H2A1, a key player in the cell cycle arrest, was detected in some neuronal nuclei, supporting that infected neurons were also blocked into the S phase. PCR studies did not support a co-infection with an adeno or herpes virus. ERK1/2 nuclear accumulation was observed in some neurons suggesting that the ERK signaling pathway might be involved as a mechanism driving these neurons far into the cell cycle.

Ph.D.'s Spend Big Bucks Hunting for Academic Jobs, with No Guaranteed Results

ERIC Educational Resources Information Center

Patton, Stacey

2013-01-01

Ph.D.'s are used to shelling out tens of thousands of dollars in the name of education. But earning the top graduate degree doesn't mean their spending has come to an end. An industry designed to help aspiring academics manage the job-application process and land tenure-track jobs is growing, and reaping the benefits of a tight market in many…

High-Performance One-Body Core/Shell Nanowire Supercapacitor Enabled by Conformal Growth of Capacitive 2D WS2 Layers.

PubMed

Choudhary, Nitin; Li, Chao; Chung, Hee-Suk; Moore, Julian; Thomas, Jayan; Jung, Yeonwoong

2016-12-27

Two-dimensional (2D) transition-metal dichalcogenides (TMDs) have emerged as promising capacitive materials for supercapacitor devices owing to their intrinsically layered structure and large surface areas. Hierarchically integrating 2D TMDs with other functional nanomaterials has recently been pursued to improve electrochemical performances; however, it often suffers from limited cyclic stabilities and capacitance losses due to the poor structural integrity at the interfaces of randomly assembled materials. Here, we report high-performance core/shell nanowire supercapacitors based on an array of one-dimensional (1D) nanowires seamlessly integrated with conformal 2D TMD layers. The 1D and 2D supercapacitor components possess "one-body" geometry with atomically sharp and structurally robust core/shell interfaces, as they were spontaneously converted from identical metal current collectors via sequential oxidation/sulfurization. These hybrid supercapacitors outperform previously developed any stand-alone 2D TMD-based supercapacitors; particularly, exhibiting an exceptional charge-discharge retention over 30,000 cycles owing to their structural robustness, suggesting great potential for unconventional energy storage technologies.

Analysis of Composite Skin-Stiffener Debond Specimens Using Volume Elements and a Shell/3D Modeling Technique

NASA Technical Reports Server (NTRS)

Krueger, Ronald; Minguet, Pierre J.; Bushnell, Dennis M. (Technical Monitor)

2002-01-01

The debonding of a skin/stringer specimen subjected to tension was studied using three-dimensional volume element modeling and computational fracture mechanics. Mixed mode strain energy release rates were calculated from finite element results using the virtual crack closure technique. The simulations revealed an increase in total energy release rate in the immediate vicinity of the free edges of the specimen. Correlation of the computed mixed-mode strain energy release rates along the delamination front contour with a two-dimensional mixed-mode interlaminar fracture criterion suggested that in spite of peak total energy release rates at the free edge the delamination would not advance at the edges first. The qualitative prediction of the shape of the delamination front was confirmed by X-ray photographs of a specimen taken during testing. The good correlation between prediction based on analysis and experiment demonstrated the efficiency of a mixed-mode failure analysis for the investigation of skin/stiffener separation due to delamination in the adherents. The application of a shell/3D modeling technique for the simulation of skin/stringer debond in a specimen subjected to three-point bending is also demonstrated. The global structure was modeled with shell elements. A local three-dimensional model, extending to about three specimen thicknesses on either side of the delamination front was used to capture the details of the damaged section. Computed total strain energy release rates and mixed-mode ratios obtained from shell/3D simulations were in good agreement with results obtained from full solid models. The good correlations of the results demonstrated the effectiveness of the shell/3D modeling technique for the investigation of skin/stiffener separation due to delamination in the adherents.

High resolution 4-D spectroscopy with sparse concentric shell sampling and FFT-CLEAN.

PubMed

Coggins, Brian E; Zhou, Pei

2008-12-01

Recent efforts to reduce the measurement time for multidimensional NMR experiments have fostered the development of a variety of new procedures for sampling and data processing. We recently described concentric ring sampling for 3-D NMR experiments, which is superior to radial sampling as input for processing by a multidimensional discrete Fourier transform. Here, we report the extension of this approach to 4-D spectroscopy as Randomized Concentric Shell Sampling (RCSS), where sampling points for the indirect dimensions are positioned on concentric shells, and where random rotations in the angular space are used to avoid coherent artifacts. With simulations, we show that RCSS produces a very low level of artifacts, even with a very limited number of sampling points. The RCSS sampling patterns can be adapted to fine rectangular grids to permit use of the Fast Fourier Transform in data processing, without an apparent increase in the artifact level. These artifacts can be further reduced to the noise level using the iterative CLEAN algorithm developed in radioastronomy. We demonstrate these methods on the high resolution 4-D HCCH-TOCSY spectrum of protein G's B1 domain, using only 1.2% of the sampling that would be needed conventionally for this resolution. The use of a multidimensional FFT instead of the slow DFT for initial data processing and for subsequent CLEAN significantly reduces the calculation time, yielding an artifact level that is on par with the level of the true spectral noise.

High Resolution 4-D Spectroscopy with Sparse Concentric Shell Sampling and FFT-CLEAN

PubMed Central

Coggins, Brian E.; Zhou, Pei

2009-01-01

SUMMARY Recent efforts to reduce the measurement time for multidimensional NMR experiments have fostered the development of a variety of new procedures for sampling and data processing. We recently described concentric ring sampling for 3-D NMR experiments, which is superior to radial sampling as input for processing by a multidimensional discrete Fourier transform. Here, we report the extension of this approach to 4-D spectroscopy as Randomized Concentric Shell Sampling (RCSS), where sampling points for the indirect dimensions are positioned on concentric shells, and where random rotations in the angular space are used to avoid coherent artifacts. With simulations, we show that RCSS produces a very low level of artifacts, even with a very limited number of sampling points. The RCSS sampling patterns can be adapted to fine rectangular grids to permit use of the Fast Fourier Transform in data processing, without an apparent increase in the artifact level. These artifacts can be further reduced to the noise level using the iterative CLEAN algorithm developed in radioastronomy. We demonstrate these methods on the high resolution 4-D HCCH-TOCSY spectrum of protein G's B1 domain, using only 1.2% of the sampling that would be needed conventionally for this resolution. The use of a multidimensional FFT instead of the slow DFT for initial data processing and for subsequent CLEAN significantly reduces the calculation time, yielding an artifact level that is on par with the level of the true spectral noise. PMID:18853260

Inverse effects of flowing phase-shift nanodroplets and lipid-shelled microbubbles on subsequent cavitation during focused ultrasound exposures.

PubMed

Zhang, Siyuan; Cui, Zhiwei; Xu, Tianqi; Liu, Pan; Li, Dapeng; Shang, Shaoqiang; Xu, Ranxiang; Zong, Yujin; Niu, Gang; Wang, Supin; He, Xijing; Wan, Mingxi

2017-01-01

This paper compared the effects of flowing phase-shift nanodroplets (NDs) and lipid-shelled microbubbles (MBs) on subsequent cavitation during focused ultrasound (FUS) exposures. The cavitation activity was monitored using a passive cavitation detection method as solutions of either phase-shift NDs or lipid-shelled MBs flowed at varying velocities through a 5-mm diameter wall-less vessel in a transparent tissue-mimicking phantom when exposed to FUS. The intensity of cavitation for the phase-shift NDs showed an upward trend with time and cavitation for the lipid-shelled MBs grew to a maximum at the outset of the FUS exposure followed by a trend of decreases when they were static in the vessel. Meanwhile, the increase of cavitation for the phase-shift NDs and decrease of cavitation for the lipid-shelled MBs had slowed down when they flowed through the vessel. During two discrete identical FUS exposures, while the normalized inertial cavitation dose (ICD) value for the lipid-shelled MB solution was higher than that for the saline in the first exposure (p-value <0.05), it decreased to almost the same level in the second exposure. For the phase-shift NDs, the normalized ICD was 0.71 in the first exposure and increased to 0.97 in the second exposure. At a low acoustic power, the normalized ICD values for the lipid-shelled MBs tended to increase with increasing velocities from 5 to 30cm/s (r>0.95). Meanwhile, the normalized ICD value for the phase-shift NDs was 0.182 at a flow velocity of 5cm/s and increased to 0.188 at a flow velocity of 15cm/s. As the flow velocity increased to 20cm/s, the normalized ICD was 0.185 and decreased to 0.178 at a flow velocity of 30cm/s. At high acoustic power, the normalized ICD values for both the lipid-shelled MBs and the phase-shift NDs increased with increasing flow velocities from 5 to 30cm/s (r>0.95). The effects of the flowing phase-shift NDs vaporized into gas bubbles as cavitation nuclei on the subsequent cavitation were inverse to

Microsacle PolySilicon Hemispherical Shell Resonating Gyroscopes with Integrated Three-dimensional Curved Electrodes

NASA Astrophysics Data System (ADS)

Zhuang, Xuye; Chen, Binggen; Wang, Xinlong; Yu, Lei; Wang, Fan; Guo, Shuwen

2018-03-01

A novel approach for fabrication of polysilicon hemispherical resonator gyroscopes with integrated 3-D curved electrodes is developed and experimentally demonstrated. The 3-D polysilicon electrodes are integrated as a part of the hemispherical shell resonator’s fabrication process, and no extra assembly process are needed, ensuring the symmetry of the shell resonator. The fabrication process and materials used are compatible with the traditional semiconductor process, indicating the gyroscope has a high potential for mass production and commercial development. Without any trimming or tuning of the n=2 wineglass frequencies, a 28 kHz shell resonator demonstrates a 0.009% frequency mismatch between two degenerate wineglass modes, and a 13.6 kHz resonator shows a frequency split of 0.03%. The ring-down time of a fabricated resonator is 0.51 s, corresponding to a Q of 22000, at 0.01 Pa vacuum and room temperature. The prototype of the gyroscope is experimentally analyzed, and the scale factor of the gyro is 1.15 mV/°/s, the bias instability is 80 °/h.

Large-scale configuration interaction description of the structure of nuclei around 100Sn and 208Pb

NASA Astrophysics Data System (ADS)

Qi, Chong

2016-08-01

In this contribution I would like to discuss briefly the recent developments of the nuclear configuration interaction shell model approach. As examples, we apply the model to calculate the structure and decay properties of low-lying states in neutron-deficient nuclei around 100Sn and 208Pb that are of great experimental and theoretical interests.

Controllable synthesis of ZnxCd1-xS@ZnO core-shell nanorods with enhanced photocatalytic activity.

PubMed

Xie, Shilei; Lu, Xihong; Zhai, Teng; Gan, Jiayong; Li, Wei; Xu, Ming; Yu, Minghao; Zhang, Yuan-Ming; Tong, Yexiang

2012-07-17

We report the synthesis of Zn(x)Cd(1-x)S@ZnO nanorod arrays via a facile two-step process and the implementation of these core-shell nanorods as an environmental friendly and recyclable photocatalyst for methyl orange degradation. The band gap of Zn(x)Cd(1-x)S@ZnO core-shell nanorods can be readily tunable by adjusting the ratio of Zn/Cd during the synthesis. These Zn(x)Cd(1-x)S@ZnO core-shell nanorods exhibit a high photocatalytic activity and good stability in the degradation of the methyl orange. Moreover, these films grown on FTO substrates make the collection and recycle of the photocatalyst easier. These findings may open new opportunities for the design of effective, stable, and easy-recyclable photocatalytic materials.

Halo Nuclei

NASA Astrophysics Data System (ADS)

Al-Khalili, Jim

2017-10-01

While neutron halos were discovered 30 years ago, this is the first book written on the subject of this exotic form of nuclei that typically contain many more neutrons than stable isotopes of those elements. It provides an introductory description of the halo and outlines the discovery and evidence for its existence. It also discusses different theoretical models of the halo's structure as well as models and techniques in reaction theory that have allowed us to study the halo. This is written at the graduate student (starting at PhD) level. The author of the book, Jim Al-Khalili, is a theoretician who published some of the key papers on the structure of the halo in the mid and late 90s and was the first to determine its true size. This monograph is based on review articles he has written on the mathematical models used to determine the halo structure and the reactions used to model that structure.

Measurement of D s + production and nuclear modification factor in Pb-Pb collisions at sqrt{{s}_{NN}}=2.76 TeV

NASA Astrophysics Data System (ADS)

Adam, J.; Adamová, D.; Aggarwal, M. M.; Aglieri Rinella, G.; Agnello, M.; Agrawal, N.; Ahammed, Z.; Ahn, S. U.; Aiola, S.; Akindinov, A.; Alam, S. N.; Aleksandrov, D.; Alessandro, B.; Alexandre, D.; Alfaro Molina, R.; Alici, A.; Alkin, A.; Almaraz, J. R. M.; Alme, J.; Alt, T.; Altinpinar, S.; Altsybeev, I.; Alves Garcia Prado, C.; Andrei, C.; Andronic, A.; Anguelov, V.; Anielski, J.; Antičić, T.; Antinori, F.; Antonioli, P.; Aphecetche, L.; Appelshäuser, H.; Arcelli, S.; Arnaldi, R.; Arnold, O. W.; Arsene, I. C.; Arslandok, M.; Audurier, B.; Augustinus, A.; Averbeck, R.; Azmi, M. D.; Badalà, A.; Baek, Y. W.; Bagnasco, S.; Bailhache, R.; Bala, R.; Baldisseri, A.; Baral, R. C.; Barbano, A. M.; Barbera, R.; Barile, F.; Barnaföldi, G. G.; Barnby, L. S.; Barret, V.; Bartalini, P.; Barth, K.; Bartke, J.; Bartsch, E.; Basile, M.; Bastid, N.; Basu, S.; Bathen, B.; Batigne, G.; Batista Camejo, A.; Batyunya, B.; Batzing, P. C.; Bearden, I. G.; Beck, H.; Bedda, C.; Behera, N. K.; Belikov, I.; Bellini, F.; Bello Martinez, H.; Bellwied, R.; Belmont, R.; Belmont-Moreno, E.; Belyaev, V.; Bencedi, G.; Beole, S.; Berceanu, I.; Bercuci, A.; Berdnikov, Y.; Berenyi, D.; Bertens, R. A.; Berzano, D.; Betev, L.; Bhasin, A.; Bhat, I. R.; Bhati, A. K.; Bhattacharjee, B.; Bhom, J.; Bianchi, L.; Bianchi, N.; Bianchin, C.; Bielčík, J.; Bielčíková, J.; Bilandzic, A.; Biswas, R.; Biswas, S.; Bjelogrlic, S.; Blair, J. T.; Blau, D.; Blume, C.; Bock, F.; Bogdanov, A.; Bøggild, H.; Boldizsár, L.; Bombara, M.; Book, J.; Borel, H.; Borissov, A.; Borri, M.; Bossú, F.; Botta, E.; Böttger, S.; Bourjau, C.; Braun-Munzinger, P.; Bregant, M.; Breitner, T.; Broker, T. A.; Browning, T. A.; Broz, M.; Brucken, E. J.; Bruna, E.; Bruno, G. E.; Budnikov, D.; Buesching, H.; Bufalino, S.; Buncic, P.; Busch, O.; Buthelezi, Z.; Butt, J. B.; Buxton, J. T.; Caffarri, D.; Cai, X.; Caines, H.; Calero Diaz, L.; Caliva, A.; Calvo Villar, E.; Camerini, P.; Carena, F.; Carena, W.; Carnesecchi, F.; Castillo Castellanos, J.; Castro, A. J.; Casula, E. A. R.; Ceballos Sanchez, C.; Cepila, J.; Cerello, P.; Cerkala, J.; Chang, B.; Chapeland, S.; Chartier, M.; Charvet, J. L.; Chattopadhyay, S.; Chattopadhyay, S.; Chelnokov, V.; Cherney, M.; Cheshkov, C.; Cheynis, B.; Chibante Barroso, V.; Chinellato, D. D.; Cho, S.; Chochula, P.; Choi, K.; Chojnacki, M.; Choudhury, S.; Christakoglou, P.; Christensen, C. H.; Christiansen, P.; Chujo, T.; Chung, S. U.; Cicalo, C.; Cifarelli, L.; Cindolo, F.; Cleymans, J.; Colamaria, F.; Colella, D.; Collu, A.; Colocci, M.; Balbastre, G. Conesa; Conesa del Valle, Z.; Connors, M. E.; Contreras, J. G.; Cormier, T. M.; Corrales Morales, Y.; Cortés Maldonado, I.; Cortese, P.; Cosentino, M. R.; Costa, F.; Crochet, P.; Cruz Albino, R.; Cuautle, E.; Cunqueiro, L.; Dahms, T.; Dainese, A.; Danu, A.; Das, D.; Das, I.; Das, S.; Dash, A.; Dash, S.; De, S.; De Caro, A.; de Cataldo, G.; de Conti, C.; de Cuveland, J.; De Falco, A.; De Gruttola, D.; De Marco, N.; De Pasquale, S.; Deisting, A.; Deloff, A.; Dénes, E.; Deplano, C.; Dhankher, P.; Di Bari, D.; Di Mauro, A.; Di Nezza, P.; Diaz Corchero, M. A.; Dietel, T.; Dillenseger, P.; Divià, R.; Djuvsland, Ø.; Dobrin, A.; Domenicis Gimenez, D.; Dönigus, B.; Dordic, O.; Drozhzhova, T.; Dubey, A. K.; Dubla, A.; Ducroux, L.; Dupieux, P.; Ehlers, R. J.; Elia, D.; Engel, H.; Epple, E.; Erazmus, B.; Erdemir, I.; Erhardt, F.; Espagnon, B.; Estienne, M.; Esumi, S.; Eum, J.; Evans, D.; Evdokimov, S.; Eyyubova, G.; Fabbietti, L.; Fabris, D.; Faivre, J.; Fantoni, A.; Fasel, M.; Feldkamp, L.; Feliciello, A.; Feofilov, G.; Ferencei, J.; Fernández Téllez, A.; Ferreiro, E. G.; Ferretti, A.; Festanti, A.; Feuillard, V. J. G.; Figiel, J.; Figueredo, M. A. S.; Filchagin, S.; Finogeev, D.; Fionda, F. M.; Fiore, E. M.; Fleck, M. G.; Floris, M.; Foertsch, S.; Foka, P.; Fokin, S.; Fragiacomo, E.; Francescon, A.; Frankenfeld, U.; Fuchs, U.; Furget, C.; Furs, A.; Fusco Girard, M.; Gaardhøje, J. J.; Gagliardi, M.; Gago, A. M.; Gallio, M.; Gangadharan, D. R.; Ganoti, P.; Gao, C.; Garabatos, C.; Garcia-Solis, E.; Gargiulo, C.; Gasik, P.; Gauger, E. F.; Germain, M.; Gheata, A.; Gheata, M.; Ghosh, P.; Ghosh, S. K.; Gianotti, P.; Giubellino, P.; Giubilato, P.; Gladysz-Dziadus, E.; Glässel, P.; Goméz Coral, D. M.; Gomez Ramirez, A.; Gonzalez, V.; González-Zamora, P.; Gorbunov, S.; Görlich, L.; Gotovac, S.; Grabski, V.; Grachov, O. A.; Graczykowski, L. K.; Graham, K. L.; Grelli, A.; Grigoras, A.; Grigoras, C.; Grigoriev, V.; Grigoryan, A.; Grigoryan, S.; Grinyov, B.; Grion, N.; Gronefeld, J. M.; Grosse-Oetringhaus, J. F.; Grossiord, J.-Y.; Grosso, R.; Guber, F.; Guernane, R.; Guerzoni, B.; Gulbrandsen, K.; Gunji, T.; Gupta, A.; Gupta, R.; Haake, R.; Haaland, Ø.; Hadjidakis, C.; Haiduc, M.; Hamagaki, H.; Hamar, G.; Harris, J. W.; Harton, A.; Hatzifotiadou, D.; Hayashi, S.; Heckel, S. T.; Heide, M.; Helstrup, H.; Herghelegiu, A.; Herrera Corral, G.; Hess, B. A.; Hetland, K. F.; Hillemanns, H.; Hippolyte, B.; Hosokawa, R.; Hristov, P.; Huang, M.; Humanic, T. J.; Hussain, N.; Hussain, T.; Hutter, D.; Hwang, D. S.; Ilkaev, R.; Inaba, M.; Innocenti, G. M.; Ippolitov, M.; Irfan, M.; Ivanov, M.; Ivanov, V.; Izucheev, V.; Jacobs, P. M.; Jadhav, M. B.; Jadlovska, S.; Jadlovsky, J.; Jahnke, C.; Jakubowska, M. J.; Jang, H. J.; Janik, M. A.; Jayarathna, P. H. S. Y.; Jena, C.; Jena, S.; Jimenez Bustamante, R. T.; Jones, P. G.; Jung, H.; Jusko, A.; Kalinak, P.; Kalweit, A.; Kamin, J.; Kang, J. H.; Kaplin, V.; Kar, S.; Karasu Uysal, A.; Karavichev, O.; Karavicheva, T.; Karayan, L.; Karpechev, E.; Kebschull, U.; Keidel, R.; Keijdener, D. L. D.; Keil, M.; Mohisin Khan, M.; Khan, P.; Khan, S. A.; Khanzadeev, A.; Kharlov, Y.; Kileng, B.; Kim, D. W.; Kim, D. J.; Kim, D.; Kim, H.; Kim, J. S.; Kim, M.; Kim, M.; Kim, S.; Kim, T.; Kirsch, S.; Kisel, I.; Kiselev, S.; Kisiel, A.; Kiss, G.; Klay, J. L.; Klein, C.; Klein, J.; Klein-Bösing, C.; Klewin, S.; Kluge, A.; Knichel, M. L.; Knospe, A. G.; Kobayashi, T.; Kobdaj, C.; Kofarago, M.; Kollegger, T.; Kolojvari, A.; Kondratiev, V.; Kondratyeva, N.; Kondratyuk, E.; Konevskikh, A.; Kopcik, M.; Kour, M.; Kouzinopoulos, C.; Kovalenko, O.; Kovalenko, V.; Kowalski, M.; Koyithatta Meethaleveedu, G.; Králik, I.; Kravčáková, A.; Kretz, M.; Krivda, M.; Krizek, F.; Kryshen, E.; Krzewicki, M.; Kubera, A. M.; Kučera, V.; Kuhn, C.; Kuijer, P. G.; Kumar, A.; Kumar, J.; Kumar, L.; Kumar, S.; Kurashvili, P.; Kurepin, A.; Kurepin, A. B.; Kuryakin, A.; Kweon, M. J.; Kwon, Y.; La Pointe, S. L.; La Rocca, P.; Ladron de Guevara, P.; Lagana Fernandes, C.; Lakomov, I.; Langoy, R.; Lara, C.; Lardeux, A.; Lattuca, A.; Laudi, E.; Lea, R.; Leardini, L.; Lee, G. R.; Lee, S.; Lehas, F.; Lemmon, R. C.; Lenti, V.; Leogrande, E.; León Monzón, I.; León Vargas, H.; Leoncino, M.; Lévai, P.; Li, S.; Li, X.; Lien, J.; Lietava, R.; Lindal, S.; Lindenstruth, V.; Lippmann, C.; Lisa, M. A.; Ljunggren, H. M.; Lodato, D. F.; Loenne, P. I.; Loginov, V.; Loizides, C.; Lopez, X.; López Torres, E.; Lowe, A.; Luettig, P.; Lunardon, M.; Luparello, G.; Maevskaya, A.; Mager, M.; Mahajan, S.; Mahmood, S. M.; Maire, A.; Majka, R. D.; Malaev, M.; Maldonado Cervantes, I.; Malinina, L.; Mal'Kevich, D.; Malzacher, P.; Mamonov, A.; Manko, V.; Manso, F.; Manzari, V.; Marchisone, M.; Mareš, J.; Margagliotti, G. V.; Margotti, A.; Margutti, J.; Marín, A.; Markert, C.; Marquard, M.; Martin, N. A.; Martin Blanco, J.; Martinengo, P.; Martínez, M. I.; Martínez García, G.; Martinez Pedreira, M.; Mas, A.; Masciocchi, S.; Masera, M.; Masoni, A.; Massacrier, L.; Mastroserio, A.; Matyja, A.; Mayer, C.; Mazer, J.; Mazzoni, M. A.; Mcdonald, D.; Meddi, F.; Melikyan, Y.; Menchaca-Rocha, A.; Meninno, E.; Mercado Pérez, J.; Meres, M.; Miake, Y.; Mieskolainen, M. M.; Mikhaylov, K.; Milano, L.; Milosevic, J.; Minervini, L. M.; Mischke, A.; Mishra, A. N.; Miskowiec, D.; Mitra, J.; Mitu, C. M.; Mohammadi, N.; Mohanty, B.; Molnar, L.; Montaño Zetina, L.; Montes, E.; Moreira De Godoy, D. A.; Moreno, L. A. P.; Moretto, S.; Morreale, A.; Morsch, A.; Muccifora, V.; Mudnic, E.; Mühlheim, D.; Muhuri, S.; Mukherjee, M.; Mulligan, J. D.; Munhoz, M. G.; Munzer, R. H.; Murray, S.; Musa, L.; Musinsky, J.; Naik, B.; Nair, R.; Nandi, B. K.; Nania, R.; Nappi, E.; Naru, M. U.; Natal da Luz, H.; Nattrass, C.; Nayak, K.; Nayak, T. K.; Nazarenko, S.; Nedosekin, A.; Nellen, L.; Ng, F.; Nicassio, M.; Niculescu, M.; Niedziela, J.; Nielsen, B. S.; Nikolaev, S.; Nikulin, S.; Nikulin, V.; Noferini, F.; Nomokonov, P.; Nooren, G.; Noris, J. C. C.; Norman, J.; Nyanin, A.; Nystrand, J.; Oeschler, H.; Oh, S.; Oh, S. K.; Ohlson, A.; Okatan, A.; Okubo, T.; Olah, L.; Oleniacz, J.; Oliveira Da Silva, A. C.; Oliver, M. H.; Onderwaater, J.; Oppedisano, C.; Orava, R.; Ortiz Velasquez, A.; Oskarsson, A.; Otwinowski, J.; Oyama, K.; Ozdemir, M.; Pachmayer, Y.; Pagano, P.; Paić, G.; Pal, S. K.; Pan, J.; Pandey, A. K.; Papcun, P.; Papikyan, V.; Pappalardo, G. S.; Pareek, P.; Park, W. J.; Parmar, S.; Passfeld, A.; Paticchio, V.; Patra, R. N.; Paul, B.; Peitzmann, T.; Pereira Da Costa, H.; Pereira De Oliveira Filho, E.; Peresunko, D.; Pérez Lara, C. E.; Perez Lezama, E.; Peskov, V.; Pestov, Y.; Petráček, V.; Petrov, V.; Petrovici, M.; Petta, C.; Piano, S.; Pikna, M.; Pillot, P.; Pinazza, O.; Pinsky, L.; Piyarathna, D. B.; Ploskon, M.; Planinic, M.; Pluta, J.; Pochybova, S.; Podesta-Lerma, P. L. M.; Poghosyan, M. G.; Polichtchouk, B.; Poljak, N.; Poonsawat, W.; Pop, A.; Porteboeuf-Houssais, S.; Porter, J.; Pospisil, J.; Prasad, S. K.; Preghenella, R.; Prino, F.; Pruneau, C. A.; Pshenichnov, I.; Puccio, M.; Puddu, G.; Pujahari, P.; Punin, V.; Putschke, J.; Qvigstad, H.; Rachevski, A.; Raha, S.; Rajput, S.; Rak, J.; Rakotozafindrabe, A.; Ramello, L.; Rami, F.; Raniwala, R.; Raniwala, S.; Räsänen, S. S.; Rascanu, B. T.; Rathee, D.; Read, K. F.; Redlich, K.; Reed, R. J.; Rehman, A.; Reichelt, P.; Reidt, F.; Ren, X.; Renfordt, R.; Reolon, A. R.; Reshetin, A.; Revol, J.-P.; Reygers, K.; Riabov, V.; Ricci, R. A.; Richert, T.; Richter, M.; Riedler, P.; Riegler, W.; Riggi, F.; Ristea, C.; Rocco, E.; Rodríguez Cahuantzi, M.; Rodriguez Manso, A.; Røed, K.; Rogochaya, E.; Rohr, D.; Röhrich, D.; Romita, R.; Ronchetti, F.; Ronflette, L.; Rosnet, P.; Rossi, A.; Roukoutakis, F.; Roy, A.; Roy, C.; Roy, P.; Rubio Montero, A. J.; Rui, R.; Russo, R.; Ryabinkin, E.; Ryabov, Y.; Rybicki, A.; Sadovsky, S.; Šafařík, K.; Sahlmuller, B.; Sahoo, P.; Sahoo, R.; Sahoo, S.; Sahu, P. K.; Saini, J.; Sakai, S.; Saleh, M. A.; Salzwedel, J.; Sambyal, S.; Samsonov, V.; Šándor, L.; Sandoval, A.; Sano, M.; Sarkar, D.; Scapparone, E.; Scarlassara, F.; Schiaua, C.; Schicker, R.; Schmidt, C.; Schmidt, H. R.; Schuchmann, S.; Schukraft, J.; Schulc, M.; Schuster, T.; Schutz, Y.; Schwarz, K.; Schweda, K.; Scioli, G.; Scomparin, E.; Scott, R.; Šefčík, M.; Seger, J. E.; Sekiguchi, Y.; Sekihata, D.; Selyuzhenkov, I.; Senosi, K.; Senyukov, S.; Serradilla, E.; Sevcenco, A.; Shabanov, A.; Shabetai, A.; Shadura, O.; Shahoyan, R.; Shangaraev, A.; Sharma, A.; Sharma, M.; Sharma, M.; Sharma, N.; Shigaki, K.; Shtejer, K.; Sibiriak, Y.; Siddhanta, S.; Sielewicz, K. M.; Siemiarczuk, T.; Silvermyr, D.; Silvestre, C.; Simatovic, G.; Simonetti, G.; Singaraju, R.; Singh, R.; Singha, S.; Singhal, V.; Sinha, B. C.; Sinha, T.; Sitar, B.; Sitta, M.; Skaali, T. B.; Slupecki, M.; Smirnov, N.; Snellings, R. J. M.; Snellman, T. W.; Søgaard, C.; Song, J.; Song, M.; Song, Z.; Soramel, F.; Sorensen, S.; Sozzi, F.; Spacek, M.; Spiriti, E.; Sputowska, I.; Spyropoulou-Stassinaki, M.; Stachel, J.; Stan, I.; Stefanek, G.; Stenlund, E.; Steyn, G.; Stiller, J. H.; Stocco, D.; Strmen, P.; Suaide, A. A. P.; Sugitate, T.; Suire, C.; Suleymanov, M.; Suljic, M.; Sultanov, R.; Šumbera, M.; Szabo, A.; Szanto de Toledo, A.; Szarka, I.; Szczepankiewicz, A.; Szymanski, M.; Tabassam, U.; Takahashi, J.; Tambave, G. J.; Tanaka, N.; Tangaro, M. A.; Tarhini, M.; Tariq, M.; Tarzila, M. G.; Tauro, A.; Tejeda Muñoz, G.; Telesca, A.; Terasaki, K.; Terrevoli, C.; Teyssier, B.; Thäder, J.; Thomas, D.; Tieulent, R.; Timmins, A. R.; Toia, A.; Trogolo, S.; Trombetta, G.; Trubnikov, V.; Trzaska, W. H.; Tsuji, T.; Tumkin, A.; Turrisi, R.; Tveter, T. S.; Ullaland, K.; Uras, A.; Usai, G. L.; Utrobicic, A.; Vajzer, M.; Vala, M.; Valencia Palomo, L.; Vallero, S.; Van Der Maarel, J.; Van Hoorne, J. W.; van Leeuwen, M.; Vanat, T.; Vande Vyvre, P.; Varga, D.; Vargas, A.; Vargyas, M.; Varma, R.; Vasileiou, M.; Vasiliev, A.; Vauthier, A.; Vechernin, V.; Veen, A. M.; Veldhoen, M.; Velure, A.; Venaruzzo, M.; Vercellin, E.; Vergara Limón, S.; Vernet, R.; Verweij, M.; Vickovic, L.; Viesti, G.; Viinikainen, J.; Vilakazi, Z.; Villalobos Baillie, O.; Villatoro Tello, A.; Vinogradov, A.; Vinogradov, L.; Vinogradov, Y.; Virgili, T.; Vislavicius, V.; Viyogi, Y. P.; Vodopyanov, A.; Völkl, M. A.; Voloshin, K.; Voloshin, S. A.; Volpe, G.; von Haller, B.; Vorobyev, I.; Vranic, D.; Vrláková, J.; Vulpescu, B.; Vyushin, A.; Wagner, B.; Wagner, J.; Wang, H.; Wang, M.; Watanabe, D.; Watanabe, Y.; Weber, M.; Weber, S. G.; Weiser, D. F.; Wessels, J. P.; Westerhoff, U.; Whitehead, A. M.; Wiechula, J.; Wikne, J.; Wilde, M.; Wilk, G.; Wilkinson, J.; Williams, M. C. S.; Windelband, B.; Winn, M.; Yaldo, C. G.; Yang, H.; Yang, P.; Yano, S.; Yasar, C.; Yin, Z.; Yokoyama, H.; Yoo, I.-K.; Yoon, J. H.; Yurchenko, V.; Yushmanov, I.; Zaborowska, A.; Zaccolo, V.; Zaman, A.; Zampolli, C.; Zanoli, H. J. C.; Zaporozhets, S.; Zardoshti, N.; Zarochentsev, A.; Závada, P.; Zaviyalov, N.; Zbroszczyk, H.; Zgura, I. S.; Zhalov, M.; Zhang, H.; Zhang, X.; Zhang, Y.; Zhang, C.; Zhang, Z.; Zhao, C.; Zhigareva, N.; Zhou, D.; Zhou, Y.; Zhou, Z.; Zhu, H.; Zhu, J.; Zichichi, A.; Zimmermann, A.; Zimmermann, M. B.; Zinovjev, G.; Zyzak, M.

2016-03-01

The production of prompt D s + mesons was measured for the first time in collisions of heavy nuclei with the ALICE detector at the LHC. The analysis was performed on a data sample of Pb-Pb collisions at a centre-of-mass energy per nucleon pair, sqrt{s_{NN}} , of 2.76 TeV in two different centrality classes, namely 0-10% and 20-50%. D s + mesons and their antiparticles were reconstructed at mid-rapidity from their hadronic decay channel D s + → ϕπ +, with ϕ → K-K+, in the transverse momentum intervals 4 < p T < 12GeV/ c and 6 < p T < 12 GeV/ c for the 0-10% and 20-50% centrality classes, respectively. The nuclear modification factor R AA was computed by comparing the p T-differential production yields in Pb-Pb collisions to those in proton-proton (pp) collisions at the same energy. This pp reference was obtained using the cross section measured at sqrt{s}=7 TeV and scaled to sqrt{s}=2.76 TeV. The R AA of D s + mesons was compared to that of non-strange D mesons in the 10% most central Pb-Pb collisions. At high p T (8 < p T < 12 GeV/ c) a suppression of the D s + -meson yield by a factor of about three, compatible within uncertainties with that of non-strange D mesons, is observed. At lower p T (4 < p T < 8 GeV/ c) the values of the D s + -meson R AA are larger than those of non-strange D mesons, although compatible within uncertainties. The production ratios D s + /D0 and D s + /D+ were also measured in Pb-Pb collisions and compared to their values in proton-proton collisions. [Figure not available: see fulltext.

Electrical properties study under radiation of the 3D-open-shell-electrode detector

NASA Astrophysics Data System (ADS)

Liu, Manwen; Li, Zheng

2018-05-01

Since the 3D-Open-Shell-Electrode Detector (3DOSED) is proposed and the structure is optimized, it is important to study 3DOSED's electrical properties to determine the detector's working performance, especially in the heavy radiation environments, like the Large Hadron Collider (LHC) and it's upgrade, the High Luminosity (HL-LHC) at CERN. In this work, full 3D technology computer-aided design (TCAD) simulations have been done on this novel silicon detector structure. Simulated detector properties include the electric field distribution, the electric potential distribution, current-voltage (I-V) characteristics, capacitance-voltage (C-V) characteristics, charge collection property, and full depletion voltage. Through the analysis of calculations and simulation results, we find that the 3DOSED's electric field and potential distributions are very uniform, even in the tiny region near the shell openings with little perturbations. The novel detector fits the designing purpose of collecting charges generated by particle/light in a good fashion with a well defined funnel shape of electric potential distribution that makes these charges drifting towards the center collection electrode. Furthermore, by analyzing the I-V, C-V, charge collection property and full depletion voltage, we can expect that the novel detector will perform well, even in the heavy radiation environments.

Strongly deformed nuclear shapes at ultra-high spin and shape coexistence in N ~ 90 nuclei

DOE PAGES

Riley, M. A.; Aguilar, A.; Evans, A. O.; ...

2009-01-01

The N ~ 90 region of the nuclear chart has featured prominently as the spectroscopy of nuclei at extreme spin has progressed. This talk will present recent discoveries from investigations of high spin behavior in the N ~ 90 Er, Tm and Yb nuclei utilizing the Gammasphere gamma-ray spectrometer. In particular it will include discussion of the beautiful shape evolution and coexistence observed in these nuclei along with the identification of a remarkable new family of band structures. The latter are very weakly populated rotational sequences with high moment of inertia that bypass the classic terminating configurations near spin 40-50h,more » marking a return to collectivity that extends discrete γ-ray spectroscopy to well over 60h. Establishing the nature of the yrast states in these nuclei beyond the oblate band-termination states has been a major goal for the past two decades. Cranking calculations suggest that these new structures most likely represent stable triaxial strongly deformed bands that lie in a valley of favored shell energy in deformation and particle-number space.« less

Near-Infrared Photoluminescence Enhancement in Ge/CdS and Ge/ZnS Core/Shell Nanocrystals: Utilizing IV/II-VI Semiconductor Epitaxy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Yijun; Rowland, Clare E; Schaller, Richard D

2014-08-26

Ge nanocrystals have a large Bohr radius and a small, size-tunable band gap that may engender direct character via strain or doping. Colloidal Ge nanocrystals are particularly interesting in the development of near-infrared materials for applications in bioimaging, telecommunications and energy conversion. Epitaxial growth of a passivating shell is a common strategy employed in the synthesis of highly luminescent II–VI, III–V and IV–VI semiconductor quantum dots. Here, we use relatively unexplored IV/II–VI epitaxy as a way to enhance the photoluminescence and improve the optical stability of colloidal Ge nanocrystals. Selected on the basis of their relatively small lattice mismatch comparedmore » with crystalline Ge, we explore the growth of epitaxial CdS and ZnS shells using the successive ion layer adsorption and reaction method. Powder X-ray diffraction and electron microscopy techniques, including energy dispersive X-ray spectroscopy and selected area electron diffraction, clearly show the controllable growth of as many as 20 epitaxial monolayers of CdS atop Ge cores. In contrast, Ge etching and/or replacement by ZnS result in relatively small Ge/ZnS nanocrystals. The presence of an epitaxial II–VI shell greatly enhances the near-infrared photoluminescence and improves the photoluminescence stability of Ge. Ge/II–VI nanocrystals are reproducibly 1–3 orders of magnitude brighter than the brightest Ge cores. Ge/4.9CdS core/shells show the highest photoluminescence quantum yield and longest radiative recombination lifetime. Thiol ligand exchange easily results in near-infrared active, water-soluble Ge/II–VI nanocrystals. We expect this synthetic IV/II–VI epitaxial approach will lead to further studies into the optoelectronic behavior and practical applications of Si and Ge-based nanomaterials.« less

Facile in situ synthesis of wurtzite ZnS/ZnO core/shell heterostructure with highly efficient visible-light photocatalytic activity and photostability

NASA Astrophysics Data System (ADS)

Xiao, Jian-Hua; Huang, Wei-Qing; Hu, Yong-sheng; Zeng, Fan; Huang, Qin-Yi; Zhou, Bing-Xin; Pan, Anlian; Li, Kai; Huang, Gui-Fang

2018-02-01

High photocatalytic activity and photostability are the pursuit of the goal for designing promising photocatalysts. Herein, using ZnO to encapsulate ZnS nanoparticles is proposed as an effective strategy to enhance photocatalytic activity and anti-photocorrosion. The ZnS/ZnO core/shell heterostructures are obtained via an annealing treatment of ZnS nanoparticles produced by a facile wet chemical approach. Due to its small size, the nascent cubic sphalerite ZnS (s-ZnS) converts into a hexagonal wurtzite ZnS (w-ZnS)/ZnO core/shell structure after annealing treatment. In situ oxidation leads to increasing ZnO, simultaneously decreasing the w-ZnS content in the resultant w-ZnS/ZnO with thermal annealing time. The w-ZnS/ZnO core/shell heterostructures show high photocatalytic activity, demonstrated by the photodegradation rate of methylene blue being up to ten-fold and seven-fold higher than that of s-ZnS under UV and visible light irradiation, respectively, and the high capability of degrading rhodamine B. The enhanced photocatalytic activity may be attributed to the large specific surface and improved charge carrier separation at the core/shell interface. Moreover, it displays high photostability owing to the protection of the ZnO shell, greatly inhibiting the photocorrosion of ZnS. This facile in situ oxidation is effective and easily scalable, providing opportunities for developing novel core/shell structure photocatalysts with high activity and photostability.

Bead-Level Characterization of Early-Stage Amyloid β42 Aggregates: Nuclei and Ionic Concentration Effects.

PubMed

Hu, Dingkun; Zhao, Wei; Zhu, Yong; Ai, Hongqi; Kang, Baotao

2017-11-16

A growing body of evidence shows that soluble β-amyloid (Aβ) aggregates, oligomers, and even protofibrils, may be more neurotoxic than fibrils. Here, we employ a coarse grain model to investigate the aggregation of 75mer Aβ 42 oligomers and the salt effect, the cornerstone of fibril evolution. We find that the oligomer morphologies generated by seventy-five monomers or mixed by both fifty monomers and five preset pentameric nuclei are different (spherical vs. bar-/disk-shaped) and are characterize by a full of coil content (former) and >70 % β-turn content (latter), indicating a novel role of the nuclei played in the early aggregation stage. The aggregation for the former oligomer adopts a master-nucleus mechanism, whereas for the latter combination of monomers and pentamers a multi-nuclei one is found. The random salt ions will distribute around the aggregates to form several ion shells as the aggregation develops. A unique two-fold gap between the shells is observed in the system containing 100 mm NaCl, endowing the physiological salt concentration with special implications. Meanwhile, an accurate ion-solute cutoff distance (0.66 nm) is predicted, and recommended to apply to many other aggregated biomolecular systems. The present distribution scenario of ions can be generalized to other aggregated systems, although it is strictly dependent on the identity of a specific aggregate, such as its charge and composition. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Review of high convergence implosion experiments with single and double shell targets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Delamater, N. D.; Watt, R. G.; Varnum, W. S.

2002-01-01

Experiments have been been performed in recent years at the Omega laser studying double shell capsules as an a1 teinative, 11011 cryogenic, path towards ignition at NTF. Double shell capsules designed to mitigate the Au M-band radiation asymmetries, were experimentally found to perform well in both spherical and cylindrical hohlraums, achieving near 1-D (-90 %) clean calculated yield at convergence comparable to that required for NIF ignition. Near-term plans include directly driven double shell experiments at Omega, which eliminates Au M-band radiation as a yield degradation m ec h an i s in.

Coherent fragmentation of 12C nuclei of momentum 4.5 GeV/ c per nucleon through the 8Beg.s.+4He channel in a nuclear photoemulsion containing lead nuclei

NASA Astrophysics Data System (ADS)

Belaga, V. V.; Gerasimov, S. G.; Dronov, V. A.; Peresadko, N. G.; Pisetskaya, A. V.; Rusakova, V. V.; Fetisov, V. N.; Kharlamov, S. P.; Shesterkina, L. N.

2017-07-01

A two-particle channel in which an unbound nucleus of 8Be in the ground state (8Beg.s.) was one of the fragments was selected among events where 12C nuclei of momentum 4.5 GeV/c per nucleon undergo coherent dissociation into three alpha particles. The events in question were detected in a track nuclear photoemulsion containing lead nuclei, which was irradiated at the synchrophasotron of the Laboratory of High Energies at the Joint Institute for Nuclear Research (JINR, Dubna). The average transverse momentum of alpha particles produced upon the decay of 8Beg.s. nuclei was 87±6 MeV/ c, while that for "single" alpha (αs) particles was 123±15 MeV/ c. The average value of the transverse-momentum transfer in the reaction being considered, Pt(12C), was 223 ± 20 MeV/ c. The average value of the cross section for this channel involving Ag and Br target nuclei was 13 ± 4 mb, while the cross section for the reaction on the Pb nucleus was 40 ± 15 mb. The Coulomb dissociation contribution evaluated on the basis of the number of events where the momentum P t(12C) did not exceed 0.1 GeV/c saturated about 20%. In nine events, the measured total transverse energy of the fragments in the reference frame comoving with the decaying carbon nucleus did not exceed 0.45 MeV, which did not contradict the excitation of the participant 12C nucleus to the level at 7.65 MeV. The average value of the transverse momentum in those events was 234 ± 25 MeV/ c.

Measurement of D s + production and nuclear modification factor in Pb-Pb collisions at $$ \\sqrt{{\\mathrm{s}}_{\\mathrm{NN}}}=2.76 $$

DOE PAGES

Adam, J.; Adamová, D.; Aggarwal, M. M.; ...

2016-03-14

Here, the production of prompt D s + mesons was measured for the first time in collisions of heavy nuclei with the ALICE detector at the LHC. The analysis was performed on a data sample of Pb-Pb collisions at a centre-of-mass energy per nucleon pair, √s NN, of 2.76 TeV in two different centrality classes, namely 0–10% and 20–50%. Ds+ mesons and their antiparticles were reconstructed at mid-rapidity from their hadronic decay channel D s + → Φπ +, with Φ → K –K +, in the transverse momentum intervals 4 < pT < 12GeV/c and 6 < pT s = 7 TeV and scaled to √s = 2.76 TeV. The RAA of D s + mesons was compared to that of non-strange D mesons in the 10% most central Pb-Pb collisions. At high p T (8 < p T < 12 GeV/c) a suppression of the D s +-meson yield by a factor of about three, compatible within uncertainties with that of non-strange D mesons, is observed. At lower p T (4 < p T < 8 GeV/c) the values of the D s +-meson R AA are larger than those of non-strange D mesons, although compatible within uncertainties. The production ratios D s +/D 0 and D s +/D + were also measured in Pb-Pb collisions and compared to their values in proton-proton collisions.« less

ZnS-Sb2S3@C Core-Double Shell Polyhedron Structure Derived from Metal-Organic Framework as Anodes for High Performance Sodium Ion Batteries.

PubMed

Dong, Shihua; Li, Caixia; Ge, Xiaoli; Li, Zhaoqiang; Miao, Xianguang; Yin, Longwei

2017-06-27

Taking advantage of zeolitic imidazolate framework (ZIF-8), ZnS-Sb 2 S 3 @C core-double shell polyhedron structure is synthesized through a sulfurization reaction between Zn 2+ dissociated from ZIF-8 and S 2- from thioacetamide (TAA), and subsequently a metal cation exchange process between Zn 2+ and Sb 3+ , in which carbon layer is introduced from polymeric resorcinol-formaldehyde to prevent the collapse of the polyhedron. The polyhedron composite with a ZnS inner-core and Sb 2 S 3 /C double-shell as anode for sodium ion batteries (SIBs) shows us a significantly improved electrochemical performance with stable cycle stability, high Coulombic efficiency and specific capacity. Peculiarly, introducing a carbon shell not only acts as an important protective layer to form a rigid construction and accommodate the volume changes, but also improves the electronic conductivity to optimize the stable cycle performance and the excellent rate property. The architecture composed of ZnS inner core and a complex Sb 2 S 3 /C shell not only facilitates the facile electrolyte infiltration to reduce the Na-ion diffusion length to improve the electrochemical reaction kinetics, but also prevents the structure pulverization caused by Na-ion insertion/extraction. This approach to prepare metal sulfides based on MOFs can be further extended to design other nanostructured systems for high performance energy storage devices.

Thin Shell Model for NIF capsule stagnation studies

NASA Astrophysics Data System (ADS)

Hammer, J. H.; Buchoff, M.; Brandon, S.; Field, J. E.; Gaffney, J.; Kritcher, A.; Nora, R. C.; Peterson, J. L.; Spears, B.; Springer, P. T.

2015-11-01

We adapt the thin shell model of Ott et al. to asymmetric ICF capsule implosions on NIF. Through much of an implosion, the shell aspect ratio is large so the thin shell approximation is well satisfied. Asymmetric pressure drive is applied using an analytic form for ablation pressure as a function of the x-ray flux, as well as time-dependent 3D drive asymmetry from hohlraum calculations. Since deviations from a sphere are small through peak velocity, we linearize the equations, decompose them by spherical harmonics and solve ODE's for the coefficients. The model gives the shell position, velocity and areal mass variations at the time of peak velocity, near 250 microns radius. The variables are used to initialize 3D rad-hydro calculations with the HYDRA and ARES codes. At link time the cold fuel shell and ablator are each characterized by a density, adiabat and mass. The thickness, position and velocity of each point are taken from the thin shell model. The interior of the shell is filled with a uniform gas density and temperature consistent with the 3/2PV energy found from 1D rad-hydro calculations. 3D linked simulations compare favorably with integrated simulations of the entire implosion. Through generating synthetic diagnostic data, the model offers a method for quickly testing hypothetical sources of asymmetry and comparing with experiment. Prepared by LLNL under Contract DE-AC52-07NA27344.

Study of Light Neutron-Rich Nuclei Using a Multilayer Semiconductor Setup

NASA Astrophysics Data System (ADS)

Gurov, Yu. B.; Lapushkin, S. V.; Sandukovsky, V. G.; Chernyshev, B. A.

2017-12-01

The characteristics of two modifications of the semiconductor (s.c.d.) setup consisting of telescopes on the basis of silicon detectors are presented. These settings allow performing a precision measurement of energy in a large dynamic range (from a few to hundreds of MeV) and particle identification in a wide range of masses. The issues of measurement of the characteristics of s.c.d. telescopes and their impact on the quality of the obtained experimental data are considered. Considerable attention is paid to the use of created semiconductor devices for the search for and spectroscopy of light exotic nuclei on the accelerators of PNPI (Gatchina) and LANL (Los Alamos).

Search for long lived heaviest nuclei beyond the valley of stability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chowdhury, P. Roy; Samanta, C.; Physics Department, Virginia Commonwealth University, Richmond, Virginia 23284-2000

2008-04-15

The existence of long lived superheavy nuclei (SHN) is controlled mainly by spontaneous fission and {alpha}-decay processes. According to microscopic nuclear theory, spherical shell effects at Z=114, 120, 126 and N=184 provide the extra stability to such SHN to have long enough lifetime to be observed. To investigate whether the so-called 'stability island' could really exist around the above Z, N values, the {alpha}-decay half-lives along with the spontaneous fission and {beta}-decay half-lives of such nuclei are studied. The {alpha}-decay half-lives of SHN with Z=102-120 are calculated in a quantum tunneling model with DDM3Y effective nuclear interaction using Q{sub {alpha}}more » values from three different mass formulas prescribed by Koura-Uno-Tachibana-Yamada (KUTY), Myers-Swiatecki (MS), and Muntian-Hofmann-Patyk-Sobiczewski (MMM). Calculation of spontaneous fission (SF) half-lives for the same SHN are carried out using a phenomenological formula and compared with SF half-lives predicted by Smolanczuk et al. A possible source of discrepancy between the calculated {alpha}-decay half-lives of some nuclei and the experimental data of GSI, JINR-FLNR, RIKEN, is discussed. In the region of Z=106-108 with N{approx}160-164, the {beta}-stable SHN {sub 106}{sup 268}Sg{sub 162} is predicted to have highest {alpha}-decay half-life (T{sub {alpha}}{approx}3.2 h) using Q{sub {alpha}} value from MMM. Interestingly, it is much greater than the recently measured T{sub {alpha}} ({approx}22 s) of deformed doubly magic {sub 108}{sup 270}Hs{sub 162} nucleus. A few fission-survived long-lived SHN which are either {beta}-stable or having large {beta}-decay half-lives are predicted to exist near {sup 294}110{sub 184}, {sup 293}110{sub 183}, {sup 296}112{sub 184}, and {sup 298}114{sub 184}. These nuclei might decay predominantly through {alpha}-particle emission.« less

Doubly magic nuclei from lattice QCD forces at MPS=469 MeV /c2

NASA Astrophysics Data System (ADS)

McIlroy, C.; Barbieri, C.; Inoue, T.; Doi, T.; Hatsuda, T.

2018-02-01

We perform ab initio self-consistent Green's function calculations of the closed shell nuclei 4He, 16O, and 40Ca, based on two-nucleon potentials derived from lattice QCD simulations, in the flavor SU(3) limit and at the pseudoscalar meson mass of 469 MeV/c2. The nucleon-nucleon interaction is obtained using the hadrons-to-atomic-nuclei-from-lattice (HAL) QCD method, and its short-distance repulsion is treated by means of ladder resummations outside the model space. Our results show that this approach diagonalizes ultraviolet degrees of freedom correctly. Therefore, ground-state energies can be obtained from infrared extrapolations even for the relatively hard potentials of HAL QCD. Comparing to previous Brueckner Hartree-Fock calculations, the total binding energies are sensibly improved by the full account of many-body correlations. The results suggest an interesting possible behavior in which nuclei are unbound at very large pion masses and islands of stability appear at first around the traditional doubly magic numbers when the pion mass is lowered toward its physical value. The calculated one-nucleon spectral distributions are qualitatively close to those of real nuclei even for the pseudoscalar meson mass considered here.

The competition between mineral dust and soot ice nuclei in mixed-phase clouds (Invited)

NASA Astrophysics Data System (ADS)

Murray, B. J.; Atkinson, J.; Umo, N.; Browse, J.; Woodhouse, M. T.; Whale, T.; Baustian, K. J.; Carslaw, K. S.; Dobbie, S.; O'Sullivan, D.; Malkin, T. L.

2013-12-01

The amount of ice present in mixed-phase clouds, which contain both supercooled liquid water droplets and ice particles, affects cloud extent, lifetime, particle size and radiative properties. The freezing of cloud droplets can be catalysed by the presence of aerosol particles known as ice nuclei. In this talk our recent laboratory and global aerosol modelling work on mineral dust and soot ice nuclei will be presented. We have performed immersion mode experiments to quantify ice nucleation by the individual minerals which make up desert mineral dusts and have shown that the feldspar component, rather than the clay component, is most important for ice nucleation (Atkinson et al. 2013). Experiments with well-characterised soot generated with eugenol, an intermediate in biomass burning, and n-decane show soot has a significant ice nucleation activity in mixed-phase cloud conditions. Our results for soot are in good agreement with previous results for acetylene soot (DeMott, 1990), but extend the efficiency to much higher temperatures. We then use a global aerosol model (GLOMAP) to map the distribution of soot and feldspar particles on a global basis. We show that below about -15oC that dust and soot together can explain most observed ice nuclei in the Earth's atmosphere, while at warmer temperatures other ice nuclei types are needed. We show that in some regions soot is the most important ice nuclei (below -15oC), while in others feldspar dust dominates. Our results suggest that there is a strong anthropogenic contribution to the ice nuclei population, since a large proportion of soot aerosol in the atmosphere results from human activities. Atkinson, J. D., Murray, B. J., Woodhouse, M. T., Carslaw, K. S., Whale, T. F., Baustian, K. J., Dobbie, S., O'Sullivan, D., and Malkin, T. L.: The importance of feldspar for ice nucleation by mineral dust in mixed-phase clouds, Nature, 10.1038/nature12278, (2013). Demott, P. J. 1990. An Exploratory-Study of Ice Nucleation by Soot

7Li(d,p)8Li transfer reaction in the NCSM/RGM approach

NASA Astrophysics Data System (ADS)

Raimondi, F.; Hupin, G.; Navrátil, P.; Quaglioni, S.

2018-03-01

Recently, we applied an ab initio method, the no-core shell model combined with the resonating group method, to the transfer reactions with light p-shell nuclei as targets and deuteron as the projectile. In particular, we studied the elastic scattering of deuterium on 7Li and the 7Li(d,p)8Li transfer reaction starting from a realistic two-nucleon interaction. In this contribution, we review of our main results on the 7Li(d,p)8Li transfer reaction, and we extend the study of the relevant reaction channels, by showing the dominant resonant phase shifts of the scattering matrix. We assess also the impact of the polarization effects of the deuteron below the breakup on the positive-parity resonant states in the reaction. For this purpose, we perform an analysis of the convergence trend of the phase and eigenphase shifts, with respect to the number of deuteron pseudostates included in the model space.

Evolvement of preformation probability of alpha cluster decay of parent nuclei 84≤Z≤92 having N=126

NASA Astrophysics Data System (ADS)

Kaur, Rupinder; Singh, Bir Bikram; Kaur, Mandeep; Sandhu, B. S.; Kaur, Maninder

2018-05-01

The preformed cluster decay model (PCM) based on collective clusterisation approach of quantum mechanical fragmentation theory (QMFT) has been applied to study the ground state decay of trans-lead parent nuclei 84≤Z≤92 with N=126 emitting α cluster. Within PCM, the α cluster is assumed to be preborn with certain preformation probability P0α before tunneling the potential barrier with penetrability Pα. The nuclear structure information of the emitted α cluster is carried out by P0α . The present work reveals that the relative P0α found to increase as the Z number of parent nuclei moves away from magic proton shell closure i.e. Z=82. It is observed that Pα also increases, consequently, shorter half life T1/2 α of α cluster decay of parent nuclei with increasing Z. The PCM calculated results for the T1/2 α of parent nuclei under study are very well compared with available experimental data.

Double shell planar experiments on OMEGA

NASA Astrophysics Data System (ADS)

Dodd, E. S.; Merritt, E. C.; Palaniyappan, S.; Montgomery, D. S.; Daughton, W. S.; Schmidt, D. W.; Cardenas, T.; Wilson, D. C.; Loomis, E. N.; Batha, S. H.; Ping, Y.; Smalyuk, V. A.; Amendt, P. A.

2017-10-01

The double shell project is aimed at fielding neutron-producing capsules at the National Ignition Facility (NIF), in which an outer low-Z ablator collides with an inner high-Z shell to compress the fuel. However, understanding these targets experimentally can be challenging when compared with conventional single shell targets. Halfraum-driven planar targets at OMEGA are being used to study physics issues important to double shell implosions outside of a convergent geometry. Both VISAR and radiography through a tube have advantages over imaging through the hohlraum and double-shell capsule at NIF. A number physics issues are being studied with this platform that include 1-d and higher dimensional effects such as defect-driven hydrodynamic instabilities from engineering features. Additionally, the use of novel materials with controlled density gradients require study in easily diagnosed 1-d systems. This work ultimately feeds back into the NIF capsule platform through manufacturing tolerances set using data from OMEGA. Supported under the US DOE by the LANS, LLC under contract DE-AC52-06NA25396. LA-UR-17-25386.

β4 systematics in rare-earth and actinide nuclei: sdg interacting boson model description

NASA Astrophysics Data System (ADS)

Devi, Y. D.; Kota, V. K. B.

1992-07-01

The observed variation of hexadecupole deformation parameter β4 with mass number A in rare-earth and actinide nuclei is studied in the sdg interacting boson model (IBM) using single j-shell Otsuka-Arima-Iachello mapped and IBM-2 to IBM-1 projected hexadecupole transition operator together with SUsdg(3) and SUsdg(5) coherent states. The SUsdg(3) limit is found to provide a good description of data.

Polarized Nuclei in a Simple Mirror Fusion Reactor

NASA Technical Reports Server (NTRS)

Noever, David A.

1995-01-01

The possibility of enhancing the ratio of output to input power Q in a simple mirror machine by polarizing Deuterium-Tritium (D- T) nuclei is evaluated. Taking the Livermore mirror reference design mirror ratio of 6.54, the expected sin(sup 2) upsilon angular distribution of fusion decay products reduces immediate losses of alpha particles to the loss cone by 7.6% and alpha-ion scattering losses by approx. 50%. Based on these findings, alpha- particle confinement times for a polarized plasma should therefore be 1.11 times greater than for isotropic nuclei. Coupling this enhanced alpha-particle heating with the expected greater than 50% D- T reaction cross section, a corresponding power ratio for polarized nuclei, Q(sub polarized), is found to be 1.63 times greater than the classical unpolarized value Q(sub classical). The effects of this increase in Q are assessed for the simple mirror.

Selective alterations of NMDAR function and plasticity in D1 and D2 medium spiny neurons in the nucleus accumbens shell following chronic intermittent ethanol exposure.

PubMed

Renteria, Rafael; Maier, Esther Y; Buske, Tavanna R; Morrisett, Richard A

2017-01-01

A major mouse model widely adopted in recent years to induce pronounced ethanol intake is the ethanol vapor model known as "CIE" or "Chronic Intermittent Ethanol." One critical question concerning this model is whether the rapid induction of high blood ethanol levels for such short time periods is sufficient to induce alterations in N-methyl-d-aspartate receptor (NMDAR) function which may contribute to excessive ethanol intake. In this study, we determined whether such short term intermittent ethanol exposure modulates NMDAR function as well as other prominent electrophysiological properties and the expression of plasticity in both D1 (D1+) and D2 (D1-) dopamine receptor expressing medium spiny neurons (MSNs) in the nucleus accumbens (NAc) shell. To distinguish between the two subtypes of MSNs in the NAc we treated Drd1a-TdTomato transgenic mice with CIE vapor and electrophysiological recordings were conducted 24 h after the last vapor exposure. To investigate CIE induced alterations in plasticity, long-term depression (LTD) was induced by pairing low frequency stimulation (LFS) with post synaptic depolarization. In ethanol naïve mice, LFS induced synaptic depression (LTD) was apparent exclusively in D1+ MSNs. Whereas in slices prepared from CIE treated mice, LFS induced synaptic potentiation (LTP) in D1+ MSNs. Furthermore, following CIE exposure, LFS now produced LTD in D1- MSNs. We found that CIE exposure induced an increase in excitability in D1+ MSNs with no change in D1- MSNs. After CIE, we found a significant increase in spontaneous EPSCs (sEPSCs) frequency in D1+ but not D1- MSNs suggesting alterations in baseline α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) mediated signaling. CIE induced changes in NMDAR function were measured using the NMDA/AMPA ratio and input-output curves of isolated NMDAR currents. We observed a significant increase in NMDAR function in D1+ MSNs and a decrease in D1- MSNs after ethanol vapor exposure. The

Design and optimization of a novel 3D detector: The 3D-open-shell-electrode detector

NASA Astrophysics Data System (ADS)

Liu, Manwen; Tan, Jian; Li, Zheng

2018-04-01

A new type of three-dimensional (3D) detector, namely 3D-Open-Shell-Electrode Detector (3DOSED), is proposed in this study. In a 3DOSED, the trench electrode can be etched all the way through the detector thickness, totally eliminating the low electric field region existed in the conventional 3D-Trench-Electrode detector. Full 3D technology computer-aided design (TCAD) simulations have been done on this novel silicon detector structure. Through comparing of the simulation results of the detector, we can obtain the best design of the 3SOSED. In addition, simulation results show that, as compared to the conventional 3D detector, the proposed 3DOSED can improve not only detector charge collection efficiency but also its radiation hardness with regard to solving the trapping problem in the detector bulk. What is more, it has been shown that detector full depletion voltage is also slightly reduced, which can improve the utility aspects of the detector. When compared to the conventional 3D detector, we find that the proposed novel 3DOSED structure has better electric potential and electric field distributions, and better electrical properties such as detector full depletion voltage. In 3DOSED array, each pixel cell is isolated from each other by highly doped trenches, but also electrically and physically connected with each other through the remaining silicon bulk between broken electrodes.

Magnetic field insensitive photoluminescence decay of ZnSe/CdS core/shell type-II colloidal quantum dots

NASA Astrophysics Data System (ADS)

Lee, Woojin; Park, Seongho; Murayama, Akihiro; Lee, Jong-soo; Kyhm, Kwangseuk

2018-06-01

We have synthesized ZnSe/CdS core/shell type-II colloidal quantum dots, where an electron and a hole are separated in the CdS shell and the ZnSe core, respectively. Our theoretical model has revealed that absorbance spectrum of bare ZnSe quantum dots in 2 nm radius becomes broadened with a large redshift (∼1.15 eV) when the electron in ZnSe core is separated by 3.2 nm CdS shell. Also, we found that our type-II QDs are insensitive to an external magnetic field up to 5 T in terms of central emission energy, degree of polarization, and photoluminescence decay time. This can be attributed to the electron–hole charge separation in a type-II structure, whereby the suppressed exchange interaction gives rise to a magnetic insensitivity with a small energy difference between the bright and dark exciton states.

Three-Dimensional Maps of All Chromosomes in Human Male Fibroblast Nuclei and Prometaphase Rosettes

PubMed Central

Bolzer, Andreas; Kreth, Gregor; Solovei, Irina; Koehler, Daniela; Saracoglu, Kaan; Fauth, Christine; Müller, Stefan; Eils, Roland; Cremer, Christoph; Speicher, Michael R

2005-01-01

Studies of higher-order chromatin arrangements are an essential part of ongoing attempts to explore changes in epigenome structure and their functional implications during development and cell differentiation. However, the extent and cell-type-specificity of three-dimensional (3D) chromosome arrangements has remained controversial. In order to overcome technical limitations of previous studies, we have developed tools that allow the quantitative 3D positional mapping of all chromosomes simultaneously. We present unequivocal evidence for a probabilistic 3D order of prometaphase chromosomes, as well as of chromosome territories (CTs) in nuclei of quiescent (G0) and cycling (early S-phase) human diploid fibroblasts (46, XY). Radial distance measurements showed a probabilistic, highly nonrandom correlation with chromosome size: small chromosomes—independently of their gene density—were distributed significantly closer to the center of the nucleus or prometaphase rosette, while large chromosomes were located closer to the nuclear or rosette rim. This arrangement was independently confirmed in both human fibroblast and amniotic fluid cell nuclei. Notably, these cell types exhibit flat-ellipsoidal cell nuclei, in contrast to the spherical nuclei of lymphocytes and several other human cell types, for which we and others previously demonstrated gene-density-correlated radial 3D CT arrangements. Modeling of 3D CT arrangements suggests that cell-type-specific differences in radial CT arrangements are not solely due to geometrical constraints that result from nuclear shape differences. We also found gene-density-correlated arrangements of higher-order chromatin shared by all human cell types studied so far. Chromatin domains, which are gene-poor, form a layer beneath the nuclear envelope, while gene-dense chromatin is enriched in the nuclear interior. We discuss the possible functional implications of this finding. PMID:15839726

Cohesive Elements for Shells

NASA Technical Reports Server (NTRS)

Davila, Carlos G.; Camanho, Pedro P.; Turon, Albert

2007-01-01

A cohesive element for shell analysis is presented. The element can be used to simulate the initiation and growth of delaminations between stacked, non-coincident layers of shell elements. The procedure to construct the element accounts for the thickness offset by applying the kinematic relations of shell deformation to transform the stiffness and internal force of a zero-thickness cohesive element such that interfacial continuity between the layers is enforced. The procedure is demonstrated by simulating the response and failure of the Mixed Mode Bending test and a skin-stiffener debond specimen. In addition, it is shown that stacks of shell elements can be used to create effective models to predict the inplane and delamination failure modes of thick components. The results indicate that simple shell models can retain many of the necessary predictive attributes of much more complex 3D models while providing the computational efficiency that is necessary for design.

Collective and non-collective structures in nuclei of mass region A ≈ 125

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, A. K.; Collaboration: INGA Collaboration; Gammasphere Collaboration

Generation of angular momentum in nuclei is a key question in nuclear structure studies. In single particle model, it is due to alignment of spin of individual nucleon available in the valence space, whereas coherent motion of nucleons are assumed in the collective model. The nuclei near the closed shell at Z = 50 with mass number A ≈ 120-125 represent ideal cases to explore the interplay between these competing mechanisms and the transition from non-collective to collective behavior or vice versa. Recent spectroscopic studies of nuclei in this region reveal several non-collective maximally aligned states representing the first kindmore » of excitation mechanism, where 8-12 particles above the {sup 114}Sn align their spins to generate these states. Deformed rotational bands feeding the non-collective states in the spin range I=20-25 and excitation energies around 10 MeV have also been observed. Structure of the collective and non-collective states are discussed in the framework of Cranked-Nilsson-Strutinsky model.« less

Growth Mechanism of Transition Metal Dichalcogenide Monolayers: The Role of Self-Seeding Fullerene Nuclei.

PubMed

Cain, Jeffrey D; Shi, Fengyuan; Wu, Jinsong; Dravid, Vinayak P

2016-05-24

Due to their unique optoelectronic properties and potential for next generation devices, monolayer transition metal dichalcogenides (TMDs) have attracted a great deal of interest since the first observation of monolayer MoS2 a few years ago. While initially isolated in monolayer form by mechanical exfoliation, the field has evolved to more sophisticated methods capable of direct growth of large-area monolayer TMDs. Chemical vapor deposition (CVD) is the technique used most prominently throughout the literature and is based on the sulfurization of transition metal oxide precursors. CVD-grown monolayers exhibit excellent quality, and this process is widely used in studies ranging from the fundamental to the applied. However, little is known about the specifics of the nucleation and growth mechanisms occurring during the CVD process. In this study, we have investigated the nucleation centers or "seeds" from which monolayer TMDs typically grow. This was accomplished using aberration-corrected scanning transmission electron microscopy to analyze the structure and composition of the nuclei present in CVD-grown MoS2-MoSe2 alloys. We find that monolayer growth proceeds from nominally oxi-chalcogenide nanoparticles which act as heterogeneous nucleation sites for monolayer growth. The oxi-chalcogenide nanoparticles are typically encased in a fullerene-like shell made of the TMD. Using this information, we propose a step-by-step nucleation and growth mechanism for monolayer TMDs. Understanding this mechanism may pave the way for precise control over the synthesis of 2D materials, heterostructures, and related complexes.

Discovery of new TeV supernova remnant shells in the Galactic plane with H.E.S.S.

NASA Astrophysics Data System (ADS)

Gottschall, D.; Capasso, M.; Deil, C.; Djannati-Atai, A.; Donath, A.; Eger, P.; Marandon, V.; Maxted, N.; Pühlhofer, G.; Renaud, M.; Sasaki, M.; Terrier, R.; Vink, J.; H.E.S.S. Collaboration

2017-01-01

Supernova remnants (SNRs) are prime candidates for efficient particle acceleration up to the knee in the cosmic ray particle spectrum. In this work we present a new method for a systematic search for new TeV-emitting SNR shells in 2864 hours of H.E.S.S. phase I data used for the H.E.S.S. Galactic Plane Survey. This new method, which correctly identifies the known shell morphologies of the TeV SNRs covered by the survey, HESS J1731-347, RX 1713.7-3946, RCW 86, and Vela Junior, reveals also the existence of three new SNR candidates. All three candidates were extensively studied regarding their morphological, spectral, and multi-wavelength (MWL) properties. HESS J1534-571 was associated with the radio SNR candidate G323.7-1.0, and thus is classified as an SNR. HESS J1912+101 and HESS J1614-518, on the other hand, do not have radio or X-ray counterparts that would permit to identify them firmly as SNRs, and therefore they remain SNR candidates, discovered first at TeV energies as such. Further MWL follow up observations are needed to confirm that these newly discovered SNR candidates are indeed SNRs.

I. T. - R. O. C. K. S. Comet Nuclei Sample Return Mission

NASA Astrophysics Data System (ADS)

Dalcher, N.

2009-04-01

Ices, organics and minerals recording the chemical evolution of the outer regions of the early solar nebula are the main constituents of comets. Because comets maintain the nearly pristine nature of the cloud where they formed, the analyses of their composition, structure, thermodynamics and isotope ratios will increase our understanding of the processes that occurred in the early phases of the solar system as well as the Interstellar Medium (ISM) Cloud that predated the formation of the solar nebula [1]. While the deep impact mission aimed at determining the internal structure of comet Temple1's nuclei [e.g. 3], the stardust mission sample return has dramatically increased our understanding of comets. Its first implications indicated that some of the comet material originated in the inner solar system and was later transported outward beyond the freezing line [4]. A wide range of organic compounds identified within different grains of the aerogel collectors has demonstrated the heterogeneity in their assemblages [5]. This suggests either many histories associated with these material or possibly analytical constraints imposed by capture heating of Wild2 material in silica aerogel. The current mission ROSETTA, will further expand our knowledge about comets considerably through rigorous in situ analyses of a Jupiter Family Comet (JFC). As the next generation of comet research post ROSETTA, we present the comet nuclei sample return mission IT - ROCKS (International Team - Return Of Comet's Key Samples) to return several minimally altered samples from various locations of comet 88P/Howell, a typical JFC. The mission scenario includes remote sensing of the comet's nucleus with onboard instruments similar to the ROSETTA instruments [6, 7, 8] (VIS, IR, Thermal IR, X-Ray, Radar) and gas/dust composition measurements including a plasma science package. Additionally two microprobes [9] will further investigate the physical properties of the comet's surface. Retrieving of the

Reversible changes in size of cell nuclei isolated from Amoeba proteus: role of the cytoskeleton.

PubMed

Pomorski, P; Grebecka, L; Grebecki, A; Makuch, R

2000-01-01

Micrurgically isolated interphasal nuclei of Amoeba proteus, which preserve F-actin cytoskeletal shells on their surface, shrink after perfusion with imidazole buffer without ATP, and expand to about 200% of their cross-sectional area upon addition of pyrophosphate. These changes in size may be reproduced several times with the same nucleus. The shrunken nuclei are insensitive to the osmotic effects of sugars and distilled water, whereas the expanded ones react only to the distilled water, showing further swelling. The shrinking-expansion cycles are partially inhibited by cytochalasins. They are attributed to the state of actomyosin complex in the perinuclear cytoskeleton, which is supposed to be in the rigor state in the imidazole buffer without ATP, and to dissociate in the presence of pyrophosphate. Inflow of external medium to the nuclei during dissociation of the myosin from the perinuclear F-actin may be due to colloidal osmosis depending on other macromolecular components of the karyoplasm.

Systematics of nn states with high spin: A study of the (α, 2He) reaction on fp shell nuclei

NASA Astrophysics Data System (ADS)

Jahn, R.; Wienands, U.; Wenzel, D.; von Neumann-Cosel, P.

1985-01-01

At 57 MeV bombarding energy the (α, 2He) reaction has been investigated on targets of 54,56Fe, 58,60,62,64Ni, 64,66Zn, and 70Ge. Selective excitation of the 2n configurations ( f{5}/{2}g{9}/{2}) 7-, ( g{9}/{2}) 8 +2, and ( g{9}/{2}2 d{5}/{2}) 6+ was observed in all final nuclei. A linear A and T dependence of the binding energies of these states was observed. This systematic behaviour is well described by the Bansal-French model. The values obtained for the strength of the isoscalar and the isovector parts of the particle-hole interaction are consistent with the average of the values describing the corresponding single-particle states.

Huntington’s disease (HD): Degeneration of select nuclei and widespread occurrence of neuronal nuclear and axonal inclusions in the brainstem

PubMed Central

Rüb, U; Hentschel, M; Stratmann, K; Brunt, ER; Heinsen, H; Seidel, K; Bouzrou, M; Auburger, G; Paulson, HL; Vonsattel, JP; Lange, HW; Korf, HW; den Dunnen, WF

2014-01-01

Huntington’s disease (HD) is a progressive polyglutamine disease that leads to a severe striatal and layer-specific neuronal loss in the cerebral neo-and allocortex. Since some of the clinical symptoms (e.g. oculomotor dysfunctions) suggested a degeneration of select brainstem nuclei we performed a systematic investigation of the brainstem of eight clinically diagnosed and genetically confirmed HD patients. This postmortem investigation revealed a consistent neuronal loss in the substantia nigra, pontine nuclei, reticulotegmental nucleus of the pons, superior and inferior olives, in the area of the excitatory burst neurons for horizontal saccades, raphe interpositus nucleus, and vestibular nuclei. Immunoreactive intranuclear neuronal inclusions were present in all degenerated and apparently spared brainstem nuclei, and immunoreactive axonal inclusions were observed in all brainstem fiber tracts of the HD patients. Degeneration of brainstem nuclei can account for a number of less well understood clinical HD symptoms (i.e. cerebellar, oculomotor and vestibular symptoms), while the formation of axonal aggregates may represent a crucial event in the cascades of pathological events leading to neurodegeneration in HD. PMID:24779419

Multi-shelled ZnCo2O4 yolk-shell spheres for high-performance acetone gas sensor

NASA Astrophysics Data System (ADS)

Xiong, Ya; Zhu, Zongye; Ding, Degong; Lu, Wenbo; Xue, Qingzhong

2018-06-01

In the present study, multi-shelled ZnCo2O4 yolk-shell spheres have been successfully prepared by using carbonaceous microspheres as templates. It is found that the multi-shelled ZnCo2O4 yolk-shell spheres based sensor shows optimal sensing performances (response value of 38.2, response/recovery time of 19 s/71 s) toward 500 ppm acetone at 200 °C. In addition, this sensor exhibits a low detection limit of 0.5 ppm acetone (response value of 1.36) and a good selectivity toward hydrogen, methane, ethanol, ammonia and carbon dioxide. Furthermore, it is demonstrated that acetone gas response of multi-shelled ZnCo2O4 yolk-shell spheres is significantly better than that of ZnCo2O4 nanotubes and ZnCo2O4 nanosheets. High acetone response of the multi-shelled ZnCo2O4 yolk-shell spheres is attributed to the enhanced gas accessibility of the multi-shell morphology caused by the small crystalline size and high specific surface area while the short response/recovery time is mainly related to the rapid gas diffusion determined by the highly porous structure. Our work puts forward an exciting opportunity in designing various yolk-shelled structures for multipurpose applications.

Dynamic variational asymptotic procedure for laminated composite shells

NASA Astrophysics Data System (ADS)

Lee, Chang-Yong

Unlike published shell theories, the main two parts of this thesis are devoted to the asymptotic construction of a refined theory for composite laminated shells valid over a wide range of frequencies and wavelengths. The resulting theory is applicable to shells each layer of which is made of materials with monoclinic symmetry. It enables one to analyze shell dynamic responses within both long-wavelength, low- and high-frequency vibration regimes. It also leads to energy functionals that are both positive definiteness and sufficient simplicity for all wavelengths. This whole procedure was first performed analytically. From the insight gained from the procedure, a finite element version of the analysis was then developed; and a corresponding computer program, DVAPAS, was developed. DVAPAS can obtain the generalized 2-D constitutive law and recover accurately the 3-D results for stress and strain in composite shells. Some independent works will be needed to develop the corresponding 2-D surface analysis associated with the present theory and to continue towards full verification and validation of the present process by comparison with available published works.

Glass shell manufacturing in space

NASA Technical Reports Server (NTRS)

Downs, R. L.; Ebner, M. A.; Nolen, R. L., Jr.

1981-01-01

Highly-uniform, hollow glass spheres (shells), which are used for inertial confinement fusion targets, were formed from metal-organic gel powder feedstock in a vertical furnace. As a result of the rapid pyrolysis caused by the furnace, the gel is transformed to a shell in five distinct stages: (a) surface closure of the porous gel; (b) generation of a closed-cell foam structure in the gel; (c) spheridization of the gel and further expansion of the foam; (d) coalescence of the closed-cell foam to a single-void shell; and (e) fining of the glass shell. The heat transfer from the furnace to the falling gel particle was modeled to determine the effective heating rate of the gel. The model predicts the temperature history for a particle as a function of mass, dimensions, specific heat, and absorptance as well as furnace temperature profile and thermal conductivity of the furnace gas. A model was developed that predicts the gravity-induced degradation of shell concentricity in falling molten shells as a function of shell characteristics and time.

Synthesis, characterization and visible-light driven photocatalysis by differently structured CdS/ZnS sandwich and core-shell nanocomposites

NASA Astrophysics Data System (ADS)

Qutub, Nida; Pirzada, Bilal Masood; Umar, Khalid; Mehraj, Owais; Muneer, M.; Sabir, Suhail

2015-11-01

CdS/ZnS sandwich and core-shell nanocomposites were synthesized by a simple and modified Chemical Precipitation method under ambient conditions. The synthesized composites were characterized by XRD, SEM, TEM, EDAX and FTIR. Optical properties were analyzed by UV-vis. Spectroscopy and the photoluminescence study was done to monitor the recombination of photo-generated charge-carriers. Thermal stability of the synthesized composites was analyzed by Thermal Gravimetric Analysis (TGA). XRD revealed the formation of nanocomposites as mixed diffraction peaks were observed in the XRD pattern. SEM and TEM showed the morphology of the nanocomposites particles and their fine particle size. EDAX revealed the appropriate molar ratios exhibited by the constituent elements in the composites and FTIR gave some characteristic peaks which indicated the formation of CdS/ZnS nanocomposites. Electrochemical Impedance Spectroscopy was done to study charge transfer properties along the nanocomposites. Photocatalytic properties of the synthesized composites were monitored by the photocatalytic kinetic study of Acid Blue dye and p-chlorophenol under visible light irradiation. Results revealed the formation of stable core-shell nanocomposites and their efficient photocatalytic properties.

Distribution of zebrin-immunoreactive Purkinje cell terminals in the cerebellar and vestibular nuclei of birds.

PubMed

Wylie, Douglas R; Pakan, Janelle M P; Huynh, Hang; Graham, David J; Iwaniuk, Andrew N

2012-05-01

Zebrin II (aldolase C) is expressed in a subset of Purkinje cells in the mammalian and avian cerebella such that there is a characteristic parasagittal organization of zebrin-immunopositive stripes alternating with zebrin-immunonegative stripes. Zebrin is expressed not only in the soma and dendrites of Purkinje cells but also in their axonal terminals. Here we describe the distribution of zebrin immunoreactivity in both the vestibular and the cerebellar nuclei of pigeons (Columba livia) and hummingbirds (Calypte anna, Selasphorus rufus). In the medial cerebellar nucleus, zebrin-positive labeling was particularly heavy in the “shell,” whereas the “core” was zebrin negative. In the lateral cerebellar nucleus, labeling was not as heavy, but a positive shell and negative core were also observed. In the vestibular nuclear complex, zebrin-positive terminal labeling was heavy in the dorsolateral vestibular nucleus and the lateral margin of the superior vestibular nucleus. The central and medial regions of the superior nucleus were generally zebrin negative. Labeling was moderate to heavy in the medial vestibular nucleus, particulary the rostral half of the parvocellular subnucleus. A moderate amount of zebrin-positive labeling was present in the descending vestibular nucleus: this was heaviest laterally, and the central region was generally zebrin negative. Zebrin-positive terminals were also observed in the the cerebellovestibular process, prepositus hypoglossi, and lateral tangential nucleus. We discuss our findings in light of similar studies in rats and with respect to the corticonuclear projections to the cerebellar nuclei and the functional connections of the vestibulocerebellum with the vestibular nuclei. Copyright © 2011 Wiley Periodicals, Inc.

Glycerol capped PbS/CdS core/shell nanoparticles at different molar ratio and its application in biosensors: An optical properties study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Das, D., E-mail: ddasphy014@gmail.com; Hussain, A. M. P.

2016-05-06

Glycerol capped PbS/CdS core/shell type nanoparticles fabricated with two different molar ratios are characterized for study of structural and optical properties. The X-ray diffraction (XRD) pattern exhibits cubic phased polycrystalline nanocrystals. The calculated grain sizes from Williamson-Hall plot were found to be around 6 nm with increased strain. HRTEM investigation confirms the formation of core/shell nanostructures and the sizes of the particles were found to be around 7 nm which is in good agreement with the results of the W-H plot. An increase of band gap with the decrease in precursor concentration is confirmed from the blue shift in the absorption spectramore » and also from Tauc plot. A clear blue shifted intense emission is observed in the photoluminescence spectra with decrease in particle size. Intense luminescence from the core/shell nanostructure may be applied in bio labelling and biosensors.« less

Mass predictions of atomic nuclei in the infinite nuclear matter model

NASA Astrophysics Data System (ADS)

Nayak, R. C.; Satpathy, L.

2012-07-01

We present here the mass excesses, binding energies, one- and two-neutron, one- and two-proton and α-particle separation energies of 6727 nuclei in the ranges 4≤Z≤120 and 8≤A≤303 calculated in the infinite nuclear matter model. Compared to our predictions of 1999 mass table, the present ones are obtained using larger data base of 2003 mass table of Wapstra and Audi and resorting to higher accuracy in the solutions of the η-differential equations of the INM model. The local energy η's supposed to carry signature of the characteristic properties of nuclei are found to possess the predictive capability. In fact η-systematics reveal new magic numbers in the drip-line regions giving rise to new islands of stability supported by relativistic mean field theoretic calculations. This is a manifestation of a new phenomenon where shell-effect overcomes the instability due to repulsive components of the nucleon-nucleon force broadening the stability peninsula. The two-neutron separation energy-systematics derived from the present mass predictions reveal a general new feature for the existence of islands of inversion in the exotic neutron-rich regions of nuclear landscape, apart from supporting the presently known islands around 31Na and 62Ti. The five global parameters representing the properties of infinite nuclear matter, the surface, the Coulomb and the pairing terms are retained as per our 1999 mass table. The root-mean-square deviation of the present mass-fit to 2198 known masses is 342 keV, while the mean deviation is 1.3 keV, reminiscent of no left-over systematic effects. This is a substantive improvement over our 1999 mass table having rms deviation of 401 keV and mean deviation of 9 keV for 1884 data nuclei.

Mass predictions of atomic nuclei in the infinite nuclear matter model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nayak, R.C., E-mail: rcnayak00@yahoo.com; Satpathy, L., E-mail: satpathy@iopb.res.in

We present here the mass excesses, binding energies, one- and two-neutron, one- and two-proton and {alpha}-particle separation energies of 6727 nuclei in the ranges 4{<=}Z{<=}120 and 8{<=}A{<=}303 calculated in the infinite nuclear matter model. Compared to our predictions of 1999 mass table, the present ones are obtained using larger data base of 2003 mass table of Wapstra and Audi and resorting to higher accuracy in the solutions of the {eta}-differential equations of the INM model. The local energy {eta}'s supposed to carry signature of the characteristic properties of nuclei are found to possess the predictive capability. In fact {eta}-systematics revealmore » new magic numbers in the drip-line regions giving rise to new islands of stability supported by relativistic mean field theoretic calculations. This is a manifestation of a new phenomenon where shell-effect overcomes the instability due to repulsive components of the nucleon-nucleon force broadening the stability peninsula. The two-neutron separation energy-systematics derived from the present mass predictions reveal a general new feature for the existence of islands of inversion in the exotic neutron-rich regions of nuclear landscape, apart from supporting the presently known islands around {sup 31}Na and {sup 62}Ti. The five global parameters representing the properties of infinite nuclear matter, the surface, the Coulomb and the pairing terms are retained as per our 1999 mass table. The root-mean-square deviation of the present mass-fit to 2198 known masses is 342 keV, while the mean deviation is 1.3 keV, reminiscent of no left-over systematic effects. This is a substantive improvement over our 1999 mass table having rms deviation of 401 keV and mean deviation of 9 keV for 1884 data nuclei.« less

Electrochemical synthesis of 1D core-shell Si/TiO2 nanotubes for lithium ion batteries

NASA Astrophysics Data System (ADS)

Kowalski, Damian; Mallet, Jeremy; Thomas, Shibin; Nemaga, Abirdu Woreka; Michel, Jean; Guery, Claude; Molinari, Michael; Morcrette, Mathieu

2017-09-01

Silicon negative electrode for lithium ion battery was designed in the form of self-organized 1D core-shell nanotubes to overcome shortcomings linked to silicon volume expansion upon lithiation/delithiation typically occurring with Si nanoparticles. The negative electrode was formed on TiO2 nanotubes in two step electrochemical synthesis by means of anodizing of titanium and electrodeposition of silicon using ionic liquid electrolytes. Remarkably, it was found that the silicon grows perpendicularly to the z-axis of nanotube and therefore its thickness can be precisely controlled by the charge passed in the electrochemical protocol. Deposited silicon creates a continuous Si network on TiO2 nanotubes without grain boundaries and particle-particle interfaces, defining its electrochemical characteristics under battery testing. In the core-shell system the titania nanotube play a role of volume expansion stabilizer framework holding the nanostructured silicon upon lithiation/delithiation. The nature of Si shell and presence of titania core determine stable performance as negative electrode tested in half cell of CR2032 coin cell battery.

Panel Stiffener Debonding Analysis using a Shell/3D Modeling Technique

NASA Technical Reports Server (NTRS)

Krueger, Ronald; Ratcliffe, James G.; Minguet, Pierre J.

2008-01-01

A shear loaded, stringer reinforced composite panel is analyzed to evaluate the fidelity of computational fracture mechanics analyses of complex structures. Shear loading causes the panel to buckle. The resulting out -of-plane deformations initiate skin/stringer separation at the location of an embedded defect. The panel and surrounding load fixture were modeled with shell elements. A small section of the stringer foot, web and noodle as well as the panel skin near the delamination front were modeled with a local 3D solid model. Across the width of the stringer fo to, the mixed-mode strain energy release rates were calculated using the virtual crack closure technique. A failure index was calculated by correlating the results with a mixed-mode failure criterion of the graphite/epoxy material. The objective was to study the effect of the fidelity of the local 3D finite element model on the computed mixed-mode strain energy release rates and the failure index.

Fast synthesis, formation mechanism, and control of shell thickness of CuS–polystyrene core–shell microspheres

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Li-min, E-mail: zhaolimin@lcu.ecu.cn; Shao, Xin; Yin, Yi-bin

2012-09-15

Graphical abstract: Core–shell structure PSt/CuS were prepared using polystyrene which were modified by 3-methacryloxypropyltrimethoxysilane as template. The coating thickness of CuS can be controlled by the amount of 3-methacryloxypropyltrimethoxysilane and the UV–vis absorption intensity of PSt/CuS composite also changed with the coating thickness of CuS. Highlights: ► Core–shell structure PSt/CuS were prepared using silanol-modified polystyrene microspheres as template. ► The coating thickness of core–shell structure PSt/CuS can be controlled by a simple method. ► The UV–vis absorption intensity of PSt/CuS composite also changed with the coating thickness of CuS. -- Abstract: The silanol-modified polystyrene microspheres were prepared through dispersion polymerization.more » Then copper sulfide particles were grown on silanol-modified polystyrene through sonochemical deposition in an aqueous bath containing copper acetate and sulfide, released through the hydrolysis of thioacetamide. The resulting particles were continuous and uniform as characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Fourier transform infrared, thermogravimetric analysis and UV–vis absorption spectroscopy were used to characterize the structure and properties of core–shell particles. The results showed the coating thickness of CuS shell can be controlled by the amount of silanol and the UV–vis absorption intensity of PSt/CuS composite also changed with the coating thickness of CuS.« less

Estimates of production and structure of nuclei with Z = 119

NASA Astrophysics Data System (ADS)

Adamian, G. G.; Antonenko, N. V.; Lenske, H.

2018-02-01

The comparative analysis of the hot fusion reactions 50Ti +247-249Bk and 51V +246-248Cm for synthesis of element 119 is made with the dinuclear system model and the prediction of nuclear properties of the microscopic-macroscopic approach, where the closed proton shell at Z ≥ 120 is expected. The quasiparticle structures of nuclei in the α-decay chain of 295119 and a possible spread of alpha energies are studied. The calculated values of Qα are compared with available experimental data. The termination of the α-decay chain of 295119 is revealed.

Shell-crossing in quasi-one-dimensional flow

NASA Astrophysics Data System (ADS)

Rampf, Cornelius; Frisch, Uriel

2017-10-01

Blow-up of solutions for the cosmological fluid equations, often dubbed shell-crossing or orbit crossing, denotes the breakdown of the single-stream regime of the cold-dark-matter fluid. At this instant, the velocity becomes multi-valued and the density singular. Shell-crossing is well understood in one dimension (1D), but not in higher dimensions. This paper is about quasi-one-dimensional (Q1D) flow that depends on all three coordinates but differs only slightly from a strictly 1D flow, thereby allowing a perturbative treatment of shell-crossing using the Euler-Poisson equations written in Lagrangian coordinates. The signature of shell-crossing is then just the vanishing of the Jacobian of the Lagrangian map, a regular perturbation problem. In essence, the problem of the first shell-crossing, which is highly singular in Eulerian coordinates, has been desingularized by switching to Lagrangian coordinates, and can then be handled by perturbation theory. Here, all-order recursion relations are obtained for the time-Taylor coefficients of the displacement field, and it is shown that the Taylor series has an infinite radius of convergence. This allows the determination of the time and location of the first shell-crossing, which is generically shown to be taking place earlier than for the unperturbed 1D flow. The time variable used for these statements is not the cosmic time t but the linear growth time τ ˜ t2/3. For simplicity, calculations are restricted to an Einstein-de Sitter universe in the Newtonian approximation, and tailored initial data are used. However it is straightforward to relax these limitations, if needed.

Collective excitations in the transitional nuclei 163Re and 165Re

NASA Astrophysics Data System (ADS)

Davis-Merry, T. R.; Joss, D. T.; Page, R. D.; Simpson, J.; Paul, E. S.; Ali, F. A.; Bianco, L.; Carroll, R. J.; Cederwall, B.; Darby, I. G.; Drummond, M. C.; Eeckhaudt, S.; Ertürk, S.; Gómez-Hornillos, M. B.; Grahn, T.; Greenlees, P. T.; Hadinia, B.; Jakobsson, U.; Jones, P. M.; Julin, R.; Juutinen, S.; Ketelhut, S.; Leino, M.; Nieminen, P.; Nyman, M.; O'Donnell, D.; Pakarinen, J.; Peura, P.; Rahkila, P.; Revill, J. P.; Ruotsalainen, P.; Sandzelius, M.; Sapple, P. J.; Sarén, J.; Sayǧi, B.; Scholey, C.; Sorri, J.; Thomson, J.; Uusitalo, J.

2015-03-01

Excited states in the neutron-deficient nuclei 75163Re88 and 75165Re90 were populated in the 106Cd( 60Ni ,p 2 n γ ) and 92Mo( 78Kr , 3 p 2 n γ ) fusion-evaporation reactions at bombarding energies of 270 and 380 MeV, respectively. γ rays were detected at the target position using the JUROGAM spectrometer while recoiling ions were separated in-flight by the RITU gas-filled recoil separator and implanted in the GREAT spectrometer. The energy level schemes for 163Re and 165Re were identified using recoil-decay correlation techniques. At low spin, the yrast bands of these isotopes consist of signature partner bands based on a single π h11 /2 quasiproton configuration. The bands display large energy splitting consistent with the soft triaxial shape typical of transitional nuclei above N =82 . The configurations of the excited states are proposed within the framework of the cranked shell model.

Synergistic effect between D-AP5 and muscimol in the nucleus accumbens shell on memory consolidation deficit in adult male Wistar rats: An isobologram analysis.

PubMed

Nasehi, Mohammad; Ostadi, Elaheh; Khakpai, Fatemeh; Ebrahimi-Ghiri, Mohaddeseh; Zarrindast, Mohammad-Reza

2017-05-01

The nucleus accumbens (NAc) glutamatergic and GABAergic systems are involved in memory processes. This study was investigated the involvement of NAc shell GABAergic system on D-AP5 induced memory consolidation deficit. The elevated plus-maze (EPM) test-retest paradigm was employed to assess memory in adult male Wistar rats. The results indicated that post-training intra-NAc shell injection of bicuculline (GABA A receptor antagonist) did not alter emotional memory consolidation. However, post-training intra-NAc shell microinjection of muscimol (GABA A receptor agonist, 0.1μg/rat) and D-AP5 (a competitive NMDA receptor antagonist, 4μg/rat) decreased emotional memory consolidation, suggesting the drugs induced amnesia. Moreover, a sub-threshold dose of muscimol (0.05μg/rat) potentiated the D-AP5 (2μg/rat) response on memory consolidation impairment. On the other hand, the middle dose of bicuculline (0.25μg/rat) reversed memory impairment induced by D-AP5 at the higher dose. Interestingly, there is a synergistic effect between D-AP5 and muscimol on impairment of emotional memory consolidation. None of the above doses changed the locomotor activity. Our results suggest that the glutamatergic and GABAergic neurons of the NAc shell interact with each other for modulation of emotional memory consolidation. Copyright © 2017 Elsevier Inc. All rights reserved.

Alternating current dielectrophoresis of core-shell nanoparticles: Experiments and comparison with theory

NASA Astrophysics Data System (ADS)

Yang, Chungja

3D particle-assemblies. Chitosan (amino sugar) and poly-L-lysine (amino acid, PLL) CSnp shell materials were custom synthesized around a hollow (gas) core by utilizing a phospholipid micelle around a volatile fluid templating for the shell material; this approach proves to be novel and distinct from conventional core-shell models wherein a conductive core is coated with an insulative shell. Experiments were conducted within a 100 nl chamber housing 100 um wide Ti/Au quadrapole electrodes spaced 25 um apart. Frequencies from 100kHz to 80MHz at fixed local field of 5Vpp were tested with 10-5 and 10-3 S/m medium conductivities for 25 seconds. Dielectrophoretic responses of ~220 and 340(or ~400) nm chitosan or PLL CSnp were compiled as a function of medium conductivity, size and shell material. Experiments further examined shell thickness and particle concentration (chapter 6) dependencies on ~530 nm CSnp dielectrophoretic and electrorotational responses with ~30nm and ~80 nm shell thicknesses and at particle concentration count rates of 5000 +/- 500, 10000 +/- 500, and 15000 +/- 500 counts per second. Using similar experimental conditions, both dielectrophoretic and electrorotational CSnp responses were compiled versus frequency, shell thickness, and particle concentration. Knowledge gained from this study includes a unique resonance-like dielectrophoretic and electrorotational spectrum, which is significantly distinct from other cells and particles. CSnp dielectric properties were then calculated by parametrically fitting parameters to an existing core-shell model. The optimum conductivity and relative permittivity for the core and the shell are 1E-15 S/m, 1, 0.6 S/m, and 90, respectively. These properties can be exploited to rapidly assemble these unique core-shell particles for future structural color production in fabrics, vehicle, and wall painting.

Preparation of ZnS@In2S3 Core@shell Composite for Enhanced Photocatalytic Degradation of Gaseous o-Dichlorobenzene under Visible Light.

PubMed

Liu, Baojun; Hu, Xia; Li, Xinyong; Li, Ying; Chen, Chang; Lam, Kwok-Ho

2017-11-27

In this study, novel ZnS@In 2 S 3 core@shell hollow nanospheres were fabricated by a facile refluxing method for the first time, and the formation mechanism of hollow structure with interior architecture was discussed based on ion-exchange Ostwald ripening. As the photocatalytic material for degradation of gaseous o-Dichlorobenzene (o-DCB), the as-synthesized core@shell hollow nanospheres were found to show significantly enhanced catalytic performance for effective separation of photo-generated charges. Moreover, the mechanisms of enhanced activity were elucidated by band alignment and unique configuration. Such photocatalyst would meet the demands for the control of persistent organic pollutant (POPs) in the atmospheric environment.

Two-photon decay of K-shell vacancies in silver atoms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mokler, P.H.; University of Giessen, Giessen; Schaeffer, H.W.

2004-09-01

The spectral distributions for the two-photon decay modes of singly K-shell ionized silver atoms are determined by x-ray-x-ray coincidence measurements. Ag K-shell vacancies were induced by nuclear electron capture decay of radioactive cadmium isotopes {sup 109}Cd and two-photon coincidences were taken back to back (180 deg.) and at a 90 deg. opening angle for the emission. Each of the two-photon transitions from the 2s, 3s, and 3d states exhibits unique angular and spectral distributions. The measurements agree nicely with relativistic self-consistent field calculations of Tong et al. Our results also confirm and extend the earlier experimental data of Ilakovac andmore » co-workers with improved accuracy.« less

Sonochemiluminescence observation of lipid- and polymer-shelled ultrasound contrast agents in 1.2 MHz focused ultrasound field.

PubMed

Qiao, Yangzi; Cao, Hua; Zhang, Shusheng; Yin, Hui; Wan, Mingxi

2013-01-01

Ultrasound contrast agents (UCAs) are frequently added into the focused ultrasound field as cavitation nuclei to enhance the therapeutic efficiency. Since their presence will distort the pressure field and make the process unpredictable, comprehension of their behaviors especially the active zone spatial distribution is an important part of better monitoring and using of UCAs. As shell materials can strongly alter the acoustic behavior of UCAs, two different shells coated UCAs, lipid-shelled and polymer-shelled UCAs, in a 1.2 MHz focused ultrasound field were studied by the Sonochemiluminescence (SCL) method and compared. The SCL spatial distribution of lipid-shelled group differed from that of polymer-shelled group. The shell material and the character of focused ultrasound field work together to the SCL distribution, causing the lipid-shelled group to have a maximum SCL intensity in pre-focal region at lower input power than that of polymer-shelled group, and a brighter SCL intensity in post-focal region at high input power. The SCL inactive area of these two groups both increased with the input power. The general behavior of the UCAs can be studied by both the average SCL intensity and the backscatter signals. As polymer-shelled UCAs are more resistant to acoustic pressure, they had a higher destruction power and showed less reactivation than lipid-shelled ones. Copyright © 2012 Elsevier B.V. All rights reserved.

Electronic and Optical Properties of Core/Shell Pb16X16/Cd52X52 (X =S, Se, Te) Quantum Dots

NASA Astrophysics Data System (ADS)

Tamukong, Patrick; Mayo, Michael; Kilina, Svetlana

2015-03-01

The electronic and optoelectronic properties of semiconductor quantum dots (QDs) are mediated by surface defects due to the presence of dangling bonds producing trap states within the HOMO-LUMO energy gap, and contributing to fluorescence quenching. Surface capping ligands are generally used to alleviate this problem and increase the quantum yields of QDs. An alternative way is to synthesize core-shell QD structures; i.e., a QD core with a shell of another semiconductor material. We have investigated the effects of Cd52X52 shells on the photoexcited dynamics of Pb16X16 (X =S, Se, Te) QDs. The thin (~ 0.50 nm) shells were found to result largely in type I core/shell structures and a blue shift of the absorption spectra. Our studies revealed fairly strong core-shell hybridization in the electronic states close to the conduction band (CB) edge for Pb16S16andPb16Se16 cores, whereas for the Pb16Te16 core, such CB states were largely shell-like in nature. Nonadiabatic DFT-based dynamics, coupled with the surface hopping method, was used to study the effects of the core and shell compositions on energy relaxation rates in these systems.

Origin of luminescence from ZnO/CdS core/shell nanowire arrays

NASA Astrophysics Data System (ADS)

Wang, Zhiqiang; Wang, Jian; Sham, Tsun-Kong; Yang, Shaoguang

2014-07-01

Chemical imaging, electronic structure and optical properties of ZnO/CdS nano-composites have been investigated using scanning transmission X-ray microscopy (STXM), X-ray absorption near-edge structure (XANES) and X-ray excited optical luminescence (XEOL) spectroscopy. STXM and XANES results confirm that the as-prepared product is ZnO/CdS core/shell nanowires (NWs), and further indicate that ZnS was formed on the surface of ZnO NWs as the interface between ZnO and CdS. The XEOL from ZnO/CdS NW arrays exhibits one weak ultraviolet (UV) emission at 375 nm, one strong green emission at 512 nm, and two broad infrared (IR) emissions at 750 and 900 nm. Combining XANES and XEOL, it is concluded that the UV luminescence is the near band gap emission (BGE) of ZnO; the green luminescence comes from both the BGE of CdS and defect emission (DE, zinc vacancies) of ZnO; the IR luminescence is attributed to the DE (bulk defect related to the S site) of CdS; ZnS contributes little to the luminescence of the ZnO/CdS NW arrays. Interestingly, the BGE and DE from oxygen vacancies of ZnO in the ZnO/CdS nano-composites are almost entirely quenched, while DE from zinc vacancies changes little.Chemical imaging, electronic structure and optical properties of ZnO/CdS nano-composites have been investigated using scanning transmission X-ray microscopy (STXM), X-ray absorption near-edge structure (XANES) and X-ray excited optical luminescence (XEOL) spectroscopy. STXM and XANES results confirm that the as-prepared product is ZnO/CdS core/shell nanowires (NWs), and further indicate that ZnS was formed on the surface of ZnO NWs as the interface between ZnO and CdS. The XEOL from ZnO/CdS NW arrays exhibits one weak ultraviolet (UV) emission at 375 nm, one strong green emission at 512 nm, and two broad infrared (IR) emissions at 750 and 900 nm. Combining XANES and XEOL, it is concluded that the UV luminescence is the near band gap emission (BGE) of ZnO; the green luminescence comes from both the

On the occurrence of nuclei in mature sieve elements.

PubMed

Event, R F; Davis, J D; Tucker, C M; Alfieri, F J

1970-12-01

The secondary phloem of 3 species of the Taxodiaceae and 13 species of woody dicotyledons was examined for the occurrence of nuclei in mature sieve elements. Nuclei were found in all mature sieve cells of Metasequoia glyptostroboides, Sequoia sempervirens and Taxodium distichum, and in some mature sieve-tube members in 12 of the 13 species of woody dicotyledons. Except for nuclei of sieve cells undergoing cessation of function, the nuclei in mature sieve cells of M. glyptostroboides, S. sempervirens and T. distichum were normal in appearance. The occurrence and morphology of nuclei in mature sieve-tube members of the woody dicotyledons were quite variable. Only 3 species, Robinia pseudoacacia, Ulmus americana and Vitis riparia, contained some mature sieve elements with apparently normal nuclei.

Melamine-assisted one-pot synthesis of hierarchical nitrogen-doped carbon@MoS2 nanowalled core-shell microspheres and their enhanced Li-storage performances

NASA Astrophysics Data System (ADS)

Sun, Fugen; Wei, Yanju; Chen, Jianzhuang; Long, Donghui; Ling, Licheng; Li, Yongsheng; Shi, Jianlin

2015-07-01

A facile and scalable one-pot approach has been developed to synthesize carbon@MoS2 core-shell microspheres by a hydrothermal method, which involves the fast formation of melamine-resorcinol-formaldehyde polymeric microspheres in situ, followed by direct growth of the MoS2 nanowalls on them. The results give unequivocal proof that melamine could be the key to forming the core-shell microspherical morphology, and the contents of MoS2 shells can be easily tuned by initial ratios of the precursors. After a simple heat treatment, the obtained carbon@MoS2 microspheres simultaneously integrate the nitrogen-doped carbon cores and the hierarchical shells which consist of few-layered MoS2 nanowalls with an expanded interlayer spacing. Their unique architectures are favourable for high electronic/ionic conductivity and accommodate volume strain during the electrochemical reaction of the MoS2 anodes in lithium-ion batteries. Thus, a very high reversibility capacity of 771 mA h g-1 at 100 mA g-1 after 100 cycles, and a rate capacity of 598 mA h g-1 at 2000 mA g-1 could be achieved for the carbon@MoS2 core-shell microspheres with the optimal composition. Furthermore, a thin carbon coating on the carbon@MoS2 microspheres could further increase the reversible capacity to 856 mA h g-1 after 100 cycles at 100 mA g-1. These encouraging results suggest that such a facile and efficient protocol can provide a new pathway to produce hierarchical core-shell microspheres which integrate the structural, morphological and compositional design rationales for advanced lithium-ion batteries.A facile and scalable one-pot approach has been developed to synthesize carbon@MoS2 core-shell microspheres by a hydrothermal method, which involves the fast formation of melamine-resorcinol-formaldehyde polymeric microspheres in situ, followed by direct growth of the MoS2 nanowalls on them. The results give unequivocal proof that melamine could be the key to forming the core-shell microspherical morphology

Alternative storage environments for shelled peanuts

USDA-ARS?s Scientific Manuscript database

Studies were conducted in small chambers and commercial storage facilities to evaluate the effect of storing shelled peanuts at 3, 13, and 21 C (38, 55, 70 F) for one year. Shelled medium runner peanuts from the 2014 crop were placed in the three different environments in Feb 2015, sampled at 60-d ...

Alternative Storage Environments for Shelled Peanuts

USDA-ARS?s Scientific Manuscript database

Studies were conducted in small chambers and commercial storage facilities to evaluate the effect of storing shelled peanuts at 3, 13, and 21 C (38, 55, 70 F) for one year. Shelled medium runner peanuts from the 2014 crop were placed in the three different environments in Feb 2015, sampled at 60-d ...

Characterization of 3D Voronoi Tessellation Nearest Neighbor Lipid Shells Provides Atomistic Lipid Disruption Profile of Protein Containing Lipid Membranes

PubMed Central

Cheng, Sara Y.; Duong, Hai V.; Compton, Campbell; Vaughn, Mark W.; Nguyen, Hoa; Cheng, Kwan H.

2015-01-01

Quantifying protein-induced lipid disruptions at the atomistic level is a challenging problem in membrane biophysics. Here we propose a novel 3D Voronoi tessellation nearest-atom-neighbor shell method to classify and characterize lipid domains into discrete concentric lipid shells surrounding membrane proteins in structurally heterogeneous lipid membranes. This method needs only the coordinates of the system and is independent of force fields and simulation conditions. As a proof-of-principle, we use this multiple lipid shell method to analyze the lipid disruption profiles of three simulated membrane systems: phosphatidylcholine, phosphatidylcholine/cholesterol, and beta-amyloid/phosphatidylcholine/cholesterol. We observed different atomic volume disruption mechanisms due to cholesterol and beta-amyloid Additionally, several lipid fractional groups and lipid-interfacial water did not converge to their control values with increasing distance or shell order from the protein. This volume divergent behavior was confirmed by bilayer thickness and chain orientational order calculations. Our method can also be used to analyze high-resolution structural experimental data. PMID:25637891

NEW CLASS OF VERY HIGH ENERGY {gamma}-RAY EMITTERS: RADIO-DARK MINI SHELLS SURROUNDING ACTIVE GALACTIC NUCLEUS JETS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kino, Motoki; Ito, Hirotaka; Kawakatu, Nozomu

We explore non-thermal emission from a shocked interstellar medium, which is identified as an expanding shell, driven by a relativistic jet in active galactic nuclei (AGNs). In this work, we particularly focus on parsec-scale size mini shells surrounding mini radio lobes. From the radio to X-ray band, the mini radio lobe emission dominates the faint emission from the mini shell. On the other hand, we find that inverse-Compton (IC) emission from the shell can overwhelm the associated lobe emission at the very high energy (VHE; E > 100 GeV) {gamma}-ray range, because energy densities of synchrotron photons from the lobemore » and/or soft photons from the AGN nucleus are large and IC scattering works effectively. The predicted IC emission from nearby mini shells can be detected with the Cherenkov Telescope Array and they are potentially a new class of VHE {gamma}-ray emitters.« less

Oxidation driven ZnS Core-ZnO shell photocatalysts under controlled oxygen atmosphere for improved photocatalytic solar water splitting

NASA Astrophysics Data System (ADS)

Bak, Daegil; Kim, Jung Hyeun

2018-06-01

Zinc type photocatalysts attract great attentions in solar hydrogen production due to their easy availability and benign environmental characteristics. Spherical ZnS particles are synthesized with a facile hydrothermal method, and they are further used as core materials to introduce ZnO shell layer surrounding the core part by partial oxidation under controlled oxygen contents. The resulting ZnS core-ZnO shell photocatalysts represent the heterostructural type II band alignment. The existence of oxide layer also influences on proton adsorption power with an aid of strong base cites derived from highly electronegative oxygen atoms in ZnO shell layer. Photocatalytic water splitting reaction is performed to evaluate catalyst efficiency under standard one sun condition, and the highest hydrogen evolution rate (1665 μmolg-1h-1) is achieved from the sample oxidized at 16.2 kPa oxygen pressure. This highest hydrogen production rate is achieved in cooperation with increased light absorption and promoted charge separations. Photoluminescence analysis reveals that the improved visible light response is obtained after thermal oxidation process due to the oxygen vacancy states in the ZnO shell layer. Therefore, overall photocatalytic efficiency in solar hydrogen production is enhanced by improved charge separations, crystallinity, and visible light responses from the ZnS core-ZnO shell structures induced by thermal oxidation.

In situ formation of a 3D core-shell and triple-conducting oxygen reduction reaction electrode for proton-conducting SOFCs

NASA Astrophysics Data System (ADS)

Zhang, Zhenbao; Wang, Jian; Chen, Yubo; Tan, Shaozao; Shao, Zongping; Chen, Dengjie

2018-05-01

BaZrxCeyY1-x-yO3-δ are recognized proton-conducting electrolyte materials for proton-conducting solid oxide fuel cells (H+-SOFCs) below 650 °C. Here Co cations are incorporated into the BaZr0.4Ce0.4Y0.2O3-δ (BZCY) scaffold to generate a 3D core-shell and triple-conducting (H+/O2-/e-) electrode in situ via infiltrating and reactive sintering. The core is the bulk BZCY scaffold, while the shell is composed of the cubic Ba(Zr0.4Ce0.4Y0.2)1-xCoxO3-δ, cubic spinel Co3O4 and cubic fluorite (Ce, Zr, Y)O2. The obtained electrode exhibits an excellent compatibility with the BZCY electrolyte, and performs well in yielding a low and stable polarization resistance for oxygen reduction reaction for intermediate-temperature H+-SOFCs. In particular, it achieves polarization resistances as low as 0.094 and 0.198 Ω cm2 at 650 and 600 °C in wet air (3% H2O) when the sintering temperature for the electrode is 900 °C. In addition, a symmetrical cell also exhibits operation stability of 70 h at 650 °C. Furthermore, a fuel cell assembled with the 3D core-shell and triple-conducting electrode delivers a peak power density of ∼330 mW cm-2 at 650 °C. The substantially improved electrochemical performance and high stability are ascribed to the unique core-shell structure and the formation of Ba(Zr0.4Ce0.4Y0.2)1-xCoxO3-δ in the shell.

Two-dimensional membrane as elastic shell with proof on the folds revealed by three-dimensional atomic mapping

NASA Astrophysics Data System (ADS)

Zhao, Jiong; Deng, Qingming; Ly, Thuc Hue; Han, Gang Hee; Sandeep, Gorantla; Rümmeli, Mark H.

2015-11-01

The great application potential for two-dimensional (2D) membranes (MoS2, WSe2, graphene and so on) aroused much effort to understand their fundamental mechanical properties. The out-of-plane bending rigidity is the key factor that controls the membrane morphology under external fields. Herein we provide an easy method to reconstruct the 3D structures of the folded edges of these 2D membranes on the atomic scale, using high-resolution (S)TEM images. After quantitative comparison with continuum mechanics shell model, it is verified that the bending behaviour of the studied 2D materials can be well explained by the linear elastic shell model. And the bending rigidities can thus be derived by fitting with our experimental results. Recall almost only theoretical approaches can access the bending properties of these 2D membranes before, now a new experimental method to measure the bending rigidity of such flexible and atomic thick 2D membranes is proposed.

Possibility of a crossed-beam experiment involving slow-neutron capture by unstable nuclei - ``rapid-process tron''

NASA Astrophysics Data System (ADS)

Yamazaki, T.; Katayama, I.; Uwamino, Y.

1993-02-01

The possibility of a crossed beam facility of slow neutrons capturing unstable nuclei is examined in connection with the Japanese Hadron Project. With a pulsed proton beam of 50 Hz repetition and with a 100 μA average beam current, one obtains a spallation neutron source of 2.4 × 10 8 thermal neutrons/cm 3/spill over a 60 cm length with a 3 ms average duration time by using a D 2O moderator. By confining radioactive nuclei of 10 9 ions in a beam circulation ring of 0.3 MHz revolution frequency, so that nuclei pass through the neutron source, one obtains a collision luminosity of 3.9 × 10 24/cm 2/s. A new research domain aimed at studying rapid processes in nuclear genetics in a laboratory will be created.

Anomalous photo-ionization of 4d shell in medium-Z ionized atoms

NASA Astrophysics Data System (ADS)

Klapisch, M.; Busquet, M.

2013-09-01

Photoionization (PI) cross sections (PICS) are necessary for the simulation of astrophysical and ICF plasmas. In order to be used in plasma modeling, the PICS are usually fit to simple analytical formulas. We observed an unusual spectral shape of the PICS of the 4d shell of ionized Xe and other elements, computed with different codes: a local minimum occurs around twice the threshold energy. We explain this phenomenon as interference between the bound 4d wavefunction and the free electron wavefunction, which is similar to the Cooper minima for neutral atoms. Consequently, the usual fitting formulas, which consist of a combination of inverse powers of the frequency beyond threshold, may yield rates for PI and radiative recombination (RR) that are incorrect by orders of magnitude. A new fitting algorithm is proposed and is included in the latest version of HULLAC.v9.5.

Multidimensional Analysis of Direct-Drive Plastic-Shell Implosions on OMEGA

NASA Astrophysics Data System (ADS)

Radha, P. B.

2004-11-01

Direct-drive implosions of plastic shells with the OMEGA laser are used as energy-scaled warm surrogates for ignition cryogenic targets designed for use on the National Ignition Facility. Plastic targets involve varying shell thickness (15 to 33 μm), fill pressures (3 to 15 atm), and shell adiabats. The multidimensional hydrodynamics code DRACO is used to evaluate the effects of capsule-surface roughness and illumination nonuniformities on target performance. These simulations indicate that shell stability during the acceleration phase plays a critical role in determining fusion yields. For shells that are thick enough to survive the Rayleigh--Taylor growth, target yields are significantly reduced by growth of the long (ℓ < 10) and intermediate modes (20 < ℓ < 50) occurring from single-beam laser nonuniformities. The neutron production rate for these thick shells truncates relative to one-dimensional (1-D) predictions. The neutron-rate curves for the thinner shells, however, have significantly lower amplitudes and widths closer to 1-D results, indicating shell breakup during the acceleration phase. The simulation results are consistent with experimental observations. Previously, the stability of plastic-shell implosions had been correlated to a static ``mix-width'' at the boundary of the gas and plastic pusher estimated using a variety of experimental observables and an assumption of spherical symmetry. Results of these 2-D simulations provide a comprehensive understanding of warm-target implosion dynamics without assumptions of spherical symmetry and serve to answer the question of the hydrodynamic surrogacy between these plastic-shell implosions and the cryogenic ignition designs.

Thiolate-Capped CdSe/ZnS Core-Shell Quantum Dots for the Sensitive Detection of Glucose.

PubMed

Abd Rahman, Samsulida; Ariffin, Nurhayati; Yusof, Nor Azah; Abdullah, Jaafar; Mohammad, Faruq; Ahmad Zubir, Zuhana; Nik Abd Aziz, Nik Mohd Azmi

2017-07-01

A semiconducting water-soluble core-shell quantum dots (QDs) system capped with thiolated ligand was used in this study for the sensitive detection of glucose in aqueous samples. The QDs selected are of CdSe-coated ZnS and were prepared in house based on a hot injection technique. The formation of ZnS shell at the outer surface of CdSe core was made via a specific process namely, SILAR (successive ionic layer adsorption and reaction). The distribution, morphology, and optical characteristics of the prepared core-shell QDs were assessed by transmission electron microscopy (TEM) and spectrofluorescence, respectively. From the analysis, the results show that the mean particle size of prepared QDs is in the range of 10-12 nm and that the optimum emission condition was displayed at 620 nm. Further, the prepared CdSe/ZnS core shell QDs were modified by means of a room temperature ligand-exchange method that involves six organic ligands, L -cysteine, L -histidine, thio-glycolic acid (TGA or mercapto-acetic acid, MAA), mercapto-propionic acid (MPA), mercapto-succinic acid (MSA), and mercapto-undecanoic acid (MUA). This process was chosen in order to maintain a very dense water solubilizing environment around the QDs surface. From the analysis, the results show that the CdSe/ZnS capped with TGA (CdSe/ZnS-TGA) exhibited the strongest fluorescence emission as compared to others; hence, it was tested further for the glucose detection after their treatment with glucose oxidase (GOx) and horseradish peroxidase (HRP) enzymes. Here in this study, the glucose detection is based on the fluorescence quenching effect of the QDs, which is correlated to the oxidative reactions occurred between the conjugated enzymes and glucose. From the analysis of results, it can be inferred that the resultant GOx:HRP/CdSe/ZnS-TGA QDs system can be a suitable platform for the fluorescence-based determination of glucose in the real samples.

Highly efficient biosensors by using well-ordered ZnO/ZnS core/shell nanotube arrays

NASA Astrophysics Data System (ADS)

Tarish, Samar; Xu, Yang; Wang, Zhijie; Mate, Faten; Al-Haddad, Ahmed; Wang, Wenxin; Lei, Yong

2017-10-01

We have studied the fabrication of highly efficient glucose sensors using well-ordered heterogeneous ZnO/ZnS core/shell nanotube arrays (CSNAs). The modified electrodes exhibit a superior electrochemical response towards ferrocyanide/ferricyanide and in glucose sensing. Further, the fabricated glucose biosensor exhibited good performance over an acceptable linear range from 2.39 × 10-5 to 2.66 × 10-4 mM, with a sensitivity of 188.34 mA mM-1 cm-2, which is higher than that of the ZnO nanotube array counterpart. A low limit of detection was realized (24 μM), which is good compared with electrodes based on conventional structures. In addition, the enhanced direct electrochemistry of glucose oxidase indicates the fast electron transfer of ZnO/ZnS CSNA electrodes, with a heterogeneous electron transfer rate constant (K s) of 1.69 s-1. The fast electron transfer is attributed to the high conductivity of the modified electrodes. The presented ZnS shell can facilitate the construction of future sensors and enhance the ZnO surface in a biological environment.

Cluster preformation law for heavy and superheavy nuclei

NASA Astrophysics Data System (ADS)

Wei, K.; Zhang, H. F.

2017-08-01

The concept of cluster radioactivity has been extended to allow emitted particles with ZC>28 for superheavy nuclei by nuclear theory [Poenaru et al., Phys. Rev. Lett. 107, 062503 (2011), 10.1103/PhysRevLett.107.062503]. The preformation and emission mechanics of heavy-ion particles must be examined again before the fascinating radioactivity is observed for superheavy nuclei in laboratory. We extract the cluster preformation factor for heavy and superheavy nuclei within a preformed cluster model, in which the decay constant is the product of the preformation factor, assault frequency, and penetration probability. The calculated results show that the cluster penetration probability for superheavy nuclei is larger than that for actinide elements. The preformation factor depends on the nuclear structures of the emitted cluster and mother nucleus, and the well-known cluster preformation law S (AC) =S (α) (AC-1 )/3 [Blendowske and Walliser, Phys. Rev. Lett. 61, 1930 (1988), 10.1103/PhysRevLett.61.1930] will break down when the mass number of the emitted cluster Ac>28 , and new preformation formulas are proposed to estimate the preformation factor for heavy and superheavy nuclei.

Green Synthesis of InP/ZnS Core/Shell Quantum Dots for Application in Heavy-Metal-Free Light-Emitting Diodes

NASA Astrophysics Data System (ADS)

Kuo, Tsung-Rong; Hung, Shih-Ting; Lin, Yen-Ting; Chou, Tzu-Lin; Kuo, Ming-Cheng; Kuo, Ya-Pei; Chen, Chia-Chun

2017-09-01

Quantum dot light-emitting diodes (QD-LEDs) have been considered as potential display technologies with the characterizations of high color purity, flexibility, transparency, and cost efficiency. For the practical applications, the development of heavy-metal-free QD-LEDs from environment-friendly materials is the most important issue to reduce the impacts on human health and environmental pollution. In this work, heavy-metal-free InP/ZnS core/shell QDs with different fluorescence were prepared by green synthesis method with low cost, safe, and environment-friendly precursors. The InP/ZnS core/shell QDs with maximum fluorescence peak at 530 nm, superior fluorescence quantum yield of 60.1%, and full width at half maximum of 55 nm were applied as an emission layer to fabricate multilayered QD-LEDs. The multilayered InP/ZnS core/shell QD-LEDs showed the turn-on voltage at 5 V, the highest luminance (160 cd/m2) at 12 V, and the external quantum efficiency of 0.223% at 6.7 V. Overall, the multilayered InP/ZnS core/shell QD-LEDs reveal potential to be the heavy-metal-free QD-LEDs for future display applications.

Stable and Flexible CuInS2/ZnS:Al-TiO2 Film for Solar-Light-Driven Photodegradation of Soil Fumigant.

PubMed

Yan, Lili; Li, Zhichun; Sun, Mingxing; Shen, Guoqing; Li, Liang

2016-08-10

Semiconductor quantum dots (QDs) are suitable light absorbers for photocatalysis because of their unique properties. However, QDs generally suffer from poor photochemical stability against air, limiting their applications in photocatalysis. In this study, a stable solar-light-driven QDs-containing photocatalytic film was developed to facilitate photocatalytic degradation of the soil fumigant 1,3-dichloropropene (1,3-D). Highly stable CuInS2/ZnS:Al core/shell QDs (CIS/ZnS:Al QDs) were synthesized by doping Al into the ZnS shell and controlling ZnS:Al shell thickness; the CIS/ZnS:Al QDs were subsequently combined with TiO2 to form a CIS/ZnS:Al-TiO2 photocatalyst. The optimized ZnS:Al shell thickness for 1,3-D photodegradation was approximately 1.3 nm, which guaranteed and balanced the good photocatalytic activity and stability of the CIS/ZnS:Al-TiO2 photocatalyst. The photodegradation efficiency of 1,3-D can be maintained up to more than 80% after five cycles during recycling experiment. When CIS/ZnS:Al-TiO2 was deposited as photocatalytic film on a flexible polyethylene terephthalate substrate, over 99% of cis-1,3-D and 98% of trans-1,3-D were depleted as they passed through the film during 15 h of irradiation under natural solar light. This study demonstrated that the stable CIS/ZnS:Al-TiO2 photocatalyst both in powder and film form is a promising agent for photodegradation and emission reduction of soil fumigants.

Improved and Robust Detection of Cell Nuclei from Four Dimensional Fluorescence Images

PubMed Central

Bashar, Md. Khayrul; Yamagata, Kazuo; Kobayashi, Tetsuya J.

2014-01-01

Segmentation-free direct methods are quite efficient for automated nuclei extraction from high dimensional images. A few such methods do exist but most of them do not ensure algorithmic robustness to parameter and noise variations. In this research, we propose a method based on multiscale adaptive filtering for efficient and robust detection of nuclei centroids from four dimensional (4D) fluorescence images. A temporal feedback mechanism is employed between the enhancement and the initial detection steps of a typical direct method. We estimate the minimum and maximum nuclei diameters from the previous frame and feed back them as filter lengths for multiscale enhancement of the current frame. A radial intensity-gradient function is optimized at positions of initial centroids to estimate all nuclei diameters. This procedure continues for processing subsequent images in the sequence. Above mechanism thus ensures proper enhancement by automated estimation of major parameters. This brings robustness and safeguards the system against additive noises and effects from wrong parameters. Later, the method and its single-scale variant are simplified for further reduction of parameters. The proposed method is then extended for nuclei volume segmentation. The same optimization technique is applied to final centroid positions of the enhanced image and the estimated diameters are projected onto the binary candidate regions to segment nuclei volumes.Our method is finally integrated with a simple sequential tracking approach to establish nuclear trajectories in the 4D space. Experimental evaluations with five image-sequences (each having 271 3D sequential images) corresponding to five different mouse embryos show promising performances of our methods in terms of nuclear detection, segmentation, and tracking. A detail analysis with a sub-sequence of 101 3D images from an embryo reveals that the proposed method can improve the nuclei detection accuracy by 9 over the previous methods

Identification of the 1s2s2p 4P5/2-->1s22s 2S1/2 magnetic quadrupole inner-shell satellite line in the Ar16+ K-shell x-ray spectrum

NASA Astrophysics Data System (ADS)

Beiersdorfer, P.; Bitter, M.; Hey, D.; Reed, K. J.

2002-09-01

We have identified the dipole-forbidden 1s2s2p 4P5/2-->1s22s 2S1/2 transition in lithiumlike Ar15+ in high-resolution K-shell x-ray emission spectra recorded at the Livermore EBIT-II electron-beam ion trap and the Princeton National Spherical Tokamak Experiment. Unlike other Ar15+ satellite lines, which can be excited by dielectronic recombination, the line is exclusively excited by electron-impact excitation. Its predicted radiative rate is comparable to that of the well-known 1s2p 3P1-->1s2 1S0 magnetic quadrupole transition in heliumlike Ar16+. As a result, it can also only be observed in low-density plasma. We present calculations of the electron-impact excitation cross sections of the innershell excited Ar15+ satellite lines, including the magnetic sublevels needed for calculating the linear line polarization. We compare these calculations to the relative magnitudes of the observed 1s2s2p-->1s22s transitions and find good agreement, confirming the identification of the lithiumlike 1s2s2p 4P5/2-->1s22s 2S1/2 magnetic quadrupole line.

Ethanol Gas Detection Using a Yolk-Shell (Core-Shell) α-Fe2O3 Nanospheres as Sensing Material.

PubMed

Wang, LiLi; Lou, Zheng; Deng, Jianan; Zhang, Rui; Zhang, Tong

2015-06-17

Three-dimensional (3D) nanostructures of α-Fe2O3 materials, including both hollow sphere-shaped and yolk-shell (core-shell)-shaped, have been successfully synthesized via an environmentally friendly hydrothermal approach. By expertly adjusting the reaction time, the solid, hollow, and yolk-shell shaped α-Fe2O3 can be selectively synthesized. Yolk-shell α-Fe2O3 nanospheres display outer diameters of 350 nm, and the interstitial hollow spaces layer is intimately sandwiched between the inner and outer shell of α-Fe2O3 nanostructures. The possible growth mechanism of the yolk-shell nanostructure is proposed. The results showed that the well-defined bilayer interface effectively enhanced the sensing performance of the α-Fe2O3 nanostructures (i.e., yolk-shell α-Fe2O3@α-Fe2O3), owing predominantly to the unique nanostructure, thus facilitated the transport rate and augmented the adsorption quantity of the target gas molecule under gas detection.

Age of heart disease presentation and dysmorphic nuclei in patients with LMNA mutations

PubMed Central

Core, Jason Q.; Mehrabi, Mehrsa; Robinson, Zachery R.; Ochs, Alexander R.; McCarthy, Linda A.; Zaragoza, Michael V.

2017-01-01

Nuclear shape defects are a distinguishing characteristic in laminopathies, cancers, and other pathologies. Correlating these defects to the symptoms, mechanisms, and progression of disease requires unbiased, quantitative, and high-throughput means of quantifying nuclear morphology. To accomplish this, we developed a method of automatically segmenting fluorescently stained nuclei in 2D microscopy images and then classifying them as normal or dysmorphic based on three geometric features of the nucleus using a package of Matlab codes. As a test case, cultured skin-fibroblast nuclei of individuals possessing LMNA splice-site mutation (c.357-2A>G), LMNA nonsense mutation (c.736 C>T, pQ246X) in exon 4, LMNA missense mutation (c.1003C>T, pR335W) in exon 6, Hutchinson-Gilford Progeria Syndrome, and no LMNA mutations were analyzed. For each cell type, the percentage of dysmorphic nuclei, and other morphological features such as average nuclear area and average eccentricity were obtained. Compared to blind observers, our procedure implemented in Matlab codes possessed similar accuracy to manual counting of dysmorphic nuclei while being significantly more consistent. The automatic quantification of nuclear defects revealed a correlation between in vitro results and age of patients for initial symptom onset. Our results demonstrate the method’s utility in experimental studies of diseases affecting nuclear shape through automated, unbiased, and accurate identification of dysmorphic nuclei. PMID:29149195

The P-factor and atomic mass systematics: Application to medium mass nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brenner, D.S.; Haustein, P.E.; Casten, R.F.

1988-01-01

The P formalism was applied to atomic mass systematics for medium and heavy nuclei. The P-factor linearizes the structure-dependent part of the nuclear mass in those regions which are free from subshell effects indicating that the attractive quadrupole p-n force plays an important role in determining the binding of valence nucleons. Where marked non-linearities occur, the P-factor provides a means for recognizing subshell closures and/or other structural features not embodied in the simple assumptions of abrupt shell or subshell changes. These are thought to be regions where the monopole part of the p-n interaction is highly orbit dependent and altersmore » the underlying single-particle structure as a function of A, N or Z. Finally, in those regions where the systematics are smooth and subshells are absent, the P-factor provides a means for predicting masses of some nuclei far-from-stability by interpolation rather than by extrapolation. 5 figs.« less

High-seniority states in spherical nuclei: Triple pair breaking in tin isotopes

NASA Astrophysics Data System (ADS)

Astier, Alain

2013-03-01

The 119-126Sn nuclei have been produced as fission fragments in two reactions induced by heavy ions: 12C+238U at 90 MeV bombarding energy, 18O+208Pb at 85 MeV. Their level schemes have been built from gamma rays detected using the Euroball array. High-spin states located above the long-lived isomeric states of the even- A and odd-A 120-126Sn nuclei have been identified. Moreover isomeric states lying around 4.5 MeV have been established in the even-A 120-126Sn from the delayed coincidences between the fission fragment detector SAPhIR and the Euroball array. All the states located above 3-MeV excitation energy are ascribed to several broken pairs of neutrons occupying the h11/2 orbit. The maximum value of angular momentum available in such a high-j shell, i.e. for mid-occupation and the breaking of the three neutron pairs (seniority v=6), has been identified.

Octupole deformations in high-K isomeric states of heavy and superheavy nuclei

NASA Astrophysics Data System (ADS)

Minkov, N.; Walker, P. M.

2016-01-01

We study the effects of quadrupole-octupole deformations on the energy and magnetic properties of high-K isomeric states in even-even heavy and superheavy nuclei. The neutron two-quasiparticle (2qp) isomeric energies and magnetic dipole moments are calculated within a deformed shell model with the Bardeen-Cooper- Schrieffer (BCS) pairing interaction over a wide range of quadrupole and octupole deformations. We found that in most cases the magnetic moments exhibit a pronounced sensitivity to the octupole deformation, while the 2qp energies indicate regions of nuclei in which the presence of high-K isomeric states may be associated with the presence of octupole softness or even with octupole deformation. In the present work we also examine the influence of the BCS pairing strength on the energy of the blocked isomer configuration. We show that the formation of 2qp energy minima in the space of quadrupole-octupole and eventually higher multipolarity deformations is a subtle effect depending on nuclear pairing correlations.

Combined plasma gas-phase synthesis and colloidal processing of InP/ZnS core/shell nanocrystals.

PubMed

Gresback, Ryan; Hue, Ryan; Gladfelter, Wayne L; Kortshagen, Uwe R

2011-01-12

Indium phosphide nanocrystals (InP NCs) with diameters ranging from 2 to 5 nm were synthesized with a scalable, flow-through, nonthermal plasma process at a rate ranging from 10 to 40 mg/h. The NC size is controlled through the plasma operating parameters, with the residence time of the gas in the plasma region strongly influencing the NC size. The NC size distribution is narrow with the standard deviation being less than 20% of the mean NC size. Zinc sulfide (ZnS) shells were grown around the plasma-synthesized InP NCs in a liquid phase reaction. Photoluminescence with quantum yields as high as 15% were observed for the InP/ZnS core-shell NCs.

Combined plasma gas-phase synthesis and colloidal processing of InP/ZnS core/shell nanocrystals

PubMed Central

2011-01-01

Indium phosphide nanocrystals (InP NCs) with diameters ranging from 2 to 5 nm were synthesized with a scalable, flow-through, nonthermal plasma process at a rate ranging from 10 to 40 mg/h. The NC size is controlled through the plasma operating parameters, with the residence time of the gas in the plasma region strongly influencing the NC size. The NC size distribution is narrow with the standard deviation being less than 20% of the mean NC size. Zinc sulfide (ZnS) shells were grown around the plasma-synthesized InP NCs in a liquid phase reaction. Photoluminescence with quantum yields as high as 15% were observed for the InP/ZnS core-shell NCs. PMID:21711589

Combined plasma gas-phase synthesis and colloidal processing of InP/ZnS core/shell nanocrystals

NASA Astrophysics Data System (ADS)

Gresback, Ryan; Hue, Ryan; Gladfelter, Wayne L.; Kortshagen, Uwe R.

2011-12-01

Indium phosphide nanocrystals (InP NCs) with diameters ranging from 2 to 5 nm were synthesized with a scalable, flow-through, nonthermal plasma process at a rate ranging from 10 to 40 mg/h. The NC size is controlled through the plasma operating parameters, with the residence time of the gas in the plasma region strongly influencing the NC size. The NC size distribution is narrow with the standard deviation being less than 20% of the mean NC size. Zinc sulfide (ZnS) shells were grown around the plasma-synthesized InP NCs in a liquid phase reaction. Photoluminescence with quantum yields as high as 15% were observed for the InP/ZnS core-shell NCs.

Measurement of the branching fractions of D s + → η ' X and D s + → η ' ρ + in e + e - → D s + D s -

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ablikim, M.

We study D + s decays to final states involving the η' with a 482 pb -1 data sample collected at √s = 4.009 GeV with the BESIII detector at the BEPCII collider. We measure the branching fractions Β(D + s → η'Χ) = (8.8 ± 1.8 ± 0.5)% and Β(D + s → η'ρ +) = (5.8 ± 1.4 ± 0.4)% where the first uncertainty is statistical and the second is systematic. In addition, we estimate an upper limit on the non-resonant branching ratio Β(D + s → η'π +π 0) < 5.1% at the 90% confidence level. Lastly,more » our results are consistent with CLEO's recent measurements and help to resolve the disagreement between the theoretical prediction and CLEO's previous measurement of Β(D + s → η'ρ +).« less

Measurement of the branching fractions of D s + → η ' X and D s + → η ' ρ + in e + e - → D s + D s -

DOE PAGES

Ablikim, M.

2015-09-30

We study D + s decays to final states involving the η' with a 482 pb -1 data sample collected at √s = 4.009 GeV with the BESIII detector at the BEPCII collider. We measure the branching fractions Β(D + s → η'Χ) = (8.8 ± 1.8 ± 0.5)% and Β(D + s → η'ρ +) = (5.8 ± 1.4 ± 0.4)% where the first uncertainty is statistical and the second is systematic. In addition, we estimate an upper limit on the non-resonant branching ratio Β(D + s → η'π +π 0) < 5.1% at the 90% confidence level. Lastly,more » our results are consistent with CLEO's recent measurements and help to resolve the disagreement between the theoretical prediction and CLEO's previous measurement of Β(D + s → η'ρ +).« less

Atomistic Design of CdSe/CdS Core-Shell Quantum Dots with Suppressed Auger Recombination.

PubMed

Jain, Ankit; Voznyy, Oleksandr; Hoogland, Sjoerd; Korkusinski, Marek; Hawrylak, Pawel; Sargent, Edward H

2016-10-12

We design quasi-type-II CdSe/CdS core-shell colloidal quantum dots (CQDs) exhibiting a suppressed Auger recombination rate. We do so using fully atomistic tight-binding wave functions and microscopic Coulomb interactions. The recombination rate as a function of the core and shell size and shape is tested against experiments. Because of a higher density of deep hole states and stronger hole confinement, Auger recombination is found to be up to six times faster for positive trions compared to negative ones in 4 nm core/10 nm shell CQDs. Soft-confinement at the interface results in weak suppression of Auger recombination compared to same-bandgap sharp-interface CQDs. We find that the suppression is due to increased volume of the core resulting in delocalization of the wave functions, rather than due to soft-confinement itself. We show that our results are consistent with previous effective mass models with the same system parameters. Increasing the dot volume remains the most efficient way to suppress Auger recombination. We predict that a 4-fold suppression of Auger recombination can be achieved in 10 nm CQDs by increasing the core volume by using rodlike cores embedded in thick shells.

Spatial distribution of nuclei in progressive nucleation: Modeling and application

NASA Astrophysics Data System (ADS)

Tomellini, Massimo

2018-04-01

Phase transformations ruled by non-simultaneous nucleation and growth do not lead to random distribution of nuclei. Since nucleation is only allowed in the untransformed portion of space, positions of nuclei are correlated. In this article an analytical approach is presented for computing pair-correlation function of nuclei in progressive nucleation. This quantity is further employed for characterizing the spatial distribution of nuclei through the nearest neighbor distribution function. The modeling is developed for nucleation in 2D space with power growth law and it is applied to describe electrochemical nucleation where correlation effects are significant. Comparison with both computer simulations and experimental data lends support to the model which gives insights into the transition from Poissonian to correlated nearest neighbor probability density.

TESTING THE ROLE OF SNe Ia FOR GALACTIC CHEMICAL EVOLUTION OF p-NUCLEI WITH TWO-DIMENSIONAL MODELS AND WITH s-PROCESS SEEDS AT DIFFERENT METALLICITIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Travaglio, C.; Gallino, R.; Rauscher, T.

2015-01-20

The bulk of p isotopes is created in the ''gamma processes'' mainly by sequences of photodisintegrations and beta decays in explosive conditions in Type Ia supernovae (SNIa) or in core collapse supernovae (ccSN). The contribution of different stellar sources to the observed distribution of p-nuclei in the solar system is still under debate. We explore single degenerate Type Ia supernovae in the framework of two-dimensional SNIa delayed-detonation explosion models. Travaglio et al. discussed the sensitivity of p-nuclei production to different SNIa models, i.e., delayed detonations of different strength, deflagrations, and the dependence on selected s-process seed distributions. Here we present amore » detailed study of p-process nucleosynthesis occurring in SNIa with s-process seeds at different metallicities. Based on the delayed-detonation model DDT-a of TRV11, we analyze the dependence of p-nucleosynthesis on the s-seed distribution obtained from different strengths of the {sup 13}C pocket. We also demonstrate that {sup 208}Pb seed alone changes the p-nuclei production considerably. The heavy-s seeds (140 ≤A < 208) contribute with about 30%-40% to the total light-p nuclei production up to {sup 132}Ba (with the exception of {sup 94}Mo and {sup 130}Ba, to which the heavy-s seeds contribute with about 15% only). Using a Galactic chemical evolution code from Travaglio et al., we study the contribution of SNIa to the solar stable p-nuclei. We find that explosions of Chandrasekhar-mass single degenerate systems produce a large amount of p-nuclei in our Galaxy, both in the range of light (A ≤ 120) and heavy p-nuclei, at almost flat average production factors (within a factor of about three). We discussed in details p-isotopes such as {sup 94}Mo with a behavior diverging from the average, which we attribute to uncertainties in the nuclear data or in SNIa modeling. Li et al. find that about 70% of all SNeIa are normal events. If these are explained in the