Evolution of E 2 transition strength in deformed hafnium isotopes from new measurements on 172Hf,174Hf, and 176Hf

NASA Astrophysics Data System (ADS)

Rudigier, M.; Nomura, K.; Dannhoff, M.; Gerst, R.-B.; Jolie, J.; Saed-Samii, N.; Stegemann, S.; Régis, J.-M.; Robledo, L. M.; Rodríguez-Guzmán, R.; Blazhev, A.; Fransen, Ch.; Warr, N.; Zell, K. O.

2015-04-01

Background: The available data for E 2 transition strengths in the region between neutron-deficient hafnium and platinum isotopes are far from complete. More and precise data are needed to enhance the picture of structure evolution in this region and to test state-of-the-art nuclear models. In a simple model, the maximum collectivity is expected at the middle of the major shell. However, for actual nuclei, particularly in heavy-mass regions, which should be highly complex, this picture may no longer be the case, and one should use a more realistic nuclear-structure model. We address this point by studying the spectroscopy of Hf as a representative case. Purpose: We remeasure the 21+ half-lives of 172,174,176Hf, for which there is some disagreement in the literature. The main goal is to measure, for the first time, the half-lives of higher-lying states of the rotational band. The new results are compared to a theoretical calculation for absolute transition strengths. Method: The half-lives were measured using γ -γ and conversion-electron-γ delayed coincidences with the fast timing method. For the determination of half-lives in the picosecond region, the generalized centroid difference method was applied. For the theoretical calculation of the spectroscopic properties, the interacting boson model is employed, whose Hamiltonian is determined based on microscopic energy-density functional calculations. Results: The measured 21+ half-lives disagree with results from earlier γ -γ fast timing measurements, but are in agreement with data from Coulomb excitation experiments and other methods. Half-lives of the 41+ and 61+ states were measured, as well as a lower limit for the 81+ states. Conclusions: This work shows the importance of a mass-dependent effective boson charge in the interacting boson model for the description of E 2 transition rates in chains of nuclei. It encourages further studies of the microscopic origin of this mass dependence. New experimental

Transition Probabilities for Hydrogen-Like Atoms

NASA Astrophysics Data System (ADS)

Jitrik, Oliverio; Bunge, Carlos F.

2004-12-01

E1, M1, E2, M2, E3, and M3 transition probabilities for hydrogen-like atoms are calculated with point-nucleus Dirac eigenfunctions for Z=1-118 and up to large quantum numbers l=25 and n=26, increasing existing data more than a thousandfold. A critical evaluation of the accuracy shows a higher reliability with respect to previous works. Tables for hydrogen containing a subset of the results are given explicitly, listing the states involved in each transition, wavelength, term energies, statistical weights, transition probabilities, oscillator strengths, and line strengths. The complete results, including 1 863 574 distinct transition probabilities, lifetimes, and branching fractions are available at http://www.fisica.unam.mx/research/tables/spectra/1el

Lithospheric strength across the ocean-continent transition in the NW of the Iberian Peninsula

NASA Astrophysics Data System (ADS)

Martín-Velázquez, Silvia; Martín-González, Fidel

2014-05-01

The main objective of this work is to investigate the relation between the strength of the lithosphere and the observed pattern of seismicity across the ocean-continent transition in the NW margin of the Iberian Peninsula. The seismicity is diffuse in this intraplate area, far from the seismically active margin of the plate: the Eurasia-African plate boundary, where convergence occurs at a rate of 4-5mm/year. The earthquake epicentres are mainly limited to an E-W trending zone (onshore seismicity is more abundant than offshore), and most earthquakes occur at depths less than 30 km, however, offshore depths are up to 150 km). Moreover, one of the problems to unravel in this area is that the seismotectonic interpretations of the anomalous seismicity in the NW peninsular are contradictory. The temperature and strength profiles have been modelled in three domains along the non-volcanic rifted West Iberian Margin: 1) the oceanic lithosphere of the Iberian Abyssal Plain, 2) the oceanic lithosphere near the ocean-continent transition of the Galicia Bank, and 3) the continental lithosphere of the NW Iberian Massif. The average bathymetry and topography have been used to fit the thermal structures of the three types of lithospheres, given that the heat flow and heat production values show a varied range. The geotherms, together with the brittle and ductile rheological laws, have been used to calculate the strength envelopes in different stress regimes (compression, shear and tensile). The continental lithosphere-asthenosphere boundary is located at 123 km and several brittle-ductile transitions appear in the crust and the mantle. However, the oceanic lithospheres are thinner (110 km near the Galicia Bank and 87 km in the Iberian Abbysal Plain) and more simple (brittle behaviour in the crust and upper mantle). The earthquake distribution is best explained by lithospheres with dry compositions and shear or tensile stress regimes. These results are similar can be compared to

Monopole transition strength function of 12C in a three-α model

NASA Astrophysics Data System (ADS)

Ishikawa, Souichi

2016-12-01

The energy-level structure of the 12C nucleus at a few MeV above the three-α (3 α ) threshold is still unsatisfactorily known. For instance, most microscopic calculations predicted that there exist one 0+ state in this energy region besides the well-known Hoyle state, whereas some experimental and theoretical studies show the existence of two 0+ states. In this paper, I will take a 3 α -boson model for bound and continuum states in 12C and study a transition process from the 12C(01+) ground state to 3 α 0+ continuum states by the electric monopole (E 0 ) operator. The strength distribution of the process will be calculated as a function of 3 α energy using the Faddeev three-body theory. The Hamiltonian for the 3 α system consists of two- and three-α potentials, and some three-α potentials with different range parameters will be examined. Results of the strength function show a double-peaked bump at the low-energy region, which can be considered as two 0+ states. The peak at higher energy may originate from a 3 α resonant state. However, it is unlikely that the peak at the lower energy is related to a resonant state, which suggests that it may be due to a so-called "ghost anomaly." Distributions of decaying particles are also calculated.

Energy levels, wavelengths, and transition rates of multipole transitions (E1, E2, M1, M2) in Au{sup 67+} and Au{sup 66+} ions

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

Hamasha, Safeia, E-mail: safeia@hu.edu.jo

2013-11-15

The fully relativistic configuration interaction method of the FAC code is used to calculate atomic data for multipole transitions in Mg-like Au (Au{sup 67+}) and Al-like Au (Au{sup 66+}) ions. Generated atomic data are important in the modeling of M-shell spectra for heavy Au ions and Au plasma diagnostics. Energy levels, oscillator strengths and transition rates are calculated for electric-dipole (E1), electric quadrupole (E2), magnetic dipole (M1), and magnetic quadrupole (M2) for transitions between excited and ground states 3l−nl{sup ′}, such that n=4,5,6,7. The local central potential is derived using the Dirac–Fock–Slater method. Correlation effects to all orders are consideredmore » by the configuration interaction expansion. All relativistic effects are included in the calculations. Calculated energy levels are compared against published values that were calculated using the multi-reference many body perturbation theory, which includes higher order QED effects. Favorable agreement was observed, with less than 0.15% difference.« less

Can the oscillator strength of the quantum dot bandgap transition exceed unity?

NASA Astrophysics Data System (ADS)

Hens, Z.

2008-10-01

We discuss the apparent contradiction between the Thomas-Reiche-Kuhn sum rule for oscillator strengths and recent experimental data on the oscillator strength of the band gap transition of quantum dots. Starting from two simple single electron model systems, we show that the sum rule does not limit this oscillator strength to values below unity, or below the number of electrons in the highest occupied single electron state. The only upper limit the sum rule imposes on the oscillator strength of the quantum dot band gap transition is the total number of electrons in the quantum dot.

VizieR Online Data Catalog: Ba V, Ba VI, and Ba VII oscillator strengths (Rauch+, 2014)

NASA Astrophysics Data System (ADS)

Rauch, T.; Werner, K.; Quinet, P.; Kruk, J. W.

2014-04-01

table1.dat contains calculated HFR oscillator strengths (loggf) and transition probabilities (gA, in 1/s) in Ba V. CF is the cancellation factor as defined by Cowan (1981). In columns 3 and 6, e is written for even and o for odd. table2.dat contains calculated HFR oscillator strengths (loggf) and transition probabilities (gA, in 1/s) in Ba VI. CF is the cancellation factor as defined by Cowan (1981). In columns 3 and 6, e is written for even and o for odd. table3.dat contains calculated HFR oscillator strengths (loggf) and transition probabilities (gA, in 1/s) in Ba VII. CF is the cancellation factor as defined by Cowan (1981). In columns 3 and 6, e is written for even and o for odd. (3 data files).

Line strengths of QED-sensitive forbidden transitions in B-, Al-, F- and Cl-like ions

NASA Astrophysics Data System (ADS)

Bilal, M.; Volotka, A. V.; Beerwerth, R.; Fritzsche, S.

2018-05-01

The magnetic dipole (M 1 ) line strength between the fine-structure levels of the ground configurations in B-, F-, Al-, and Cl-like ions are calculated for the four elements argon, iron, molybdenum, and tungsten. Systematically enlarged multiconfiguration Dirac-Hartree-Fock (MCDHF) wave functions are employed to account for the interelectronic interaction with the Breit interaction included in first-order perturbation theory. The QED corrections are evaluated to all orders in α Z utilizing an effective potential approach. The calculated line strengths are compared with the results of other theories. The M 1 transition rates are reported using accurate energies from the literature. Moreover, the lifetimes in the range of millisecond to picosecond are predicted including the contributions from the transition rate due to the E 2 transition channel. The discrepancies of the predicted rates from those available from the literature are discussed and a benchmark data set of theoretical lifetimes is provided to support future experiments.

Effective Collision Strengths for Fine-structure Transitions in Si VII

NASA Astrophysics Data System (ADS)

Sossah, A. M.; Tayal, S. S.

2014-05-01

The effective collision strengths for electron-impact excitation of fine-structure transitions in Si VII are calculated as a function of electron temperature in the range 5000-2,000,000 K. The B-spline Breit-Pauli R-matrix method has been used to calculate collision strengths by electron impact. The target wave functions have been obtained using the multi-configuration Hartree-Fock method with term-dependent non-orthogonal orbitals. The 92 fine-structure levels belonging to the 46 LS states of 2s 22p 4, 2s2p 5, 2p 6, 2s 22p 33s, 2s 22p 33p, 2s 22p 33d, and 2s2p 43s configurations are included in our calculations of oscillator strengths and collision strengths. There are 4186 possible fine-structure allowed and forbidden transitions among the 92 levels. The present excitation energies, oscillator strengths, and collision strengths have been compared with previous theoretical results and available experimental data. Generally, a good agreement is found with the 6 LS-state close-coupling approximation results of Butler & Zeippen and the 44 LS-state distorted wave calculation of Bhatia & Landi.

High-resolution study of Gamow-Teller transitions via the 54Fe(3He,t)54Co reaction

NASA Astrophysics Data System (ADS)

Adachi, T.; Fujita, Y.; Bacher, A. D.; Berg, G. P. A.; Black, T.; de Frenne, D.; Foster, C. C.; Fujita, H.; Fujita, K.; Hatanaka, K.; Honma, M.; Jacobs, E.; Jänecke, J.; Kanzaki, K.; Katori, K.; Nakanishi, K.; Negret, A.; Otsuka, T.; Popescu, L.; Roberts, D. A.; Sakemi, Y.; Shimbara, Y.; Shimizu, Y.; Stephenson, E. J.; Tameshige, Y.; Tamii, A.; Uchida, M.; Ueno, H.; Yamanaka, T.; Yosoi, M.; Zell, K. O.

2012-02-01

The Gamow-Teller transition strengths, B(GT), in pf-shell nuclei are of interest in nuclear physics as well as in nuclear astrophysics. A high-resolution (3He,t) charge-exchange (CE) reaction was performed on the Tz=+1 nucleus 54Fe at 0∘ and at an intermediate incident energy of 140 MeV/nucleon for the study of precise GT transition strengths to the final Tz=0 nucleus 54Co. By applying dispersion matching techniques for a high-quality 3He beam at RCNP, an energy resolution of 21 keV and an angular resolution of 5 mr were realized. The bumplike structure of the GT resonance observed in low-resolution CE reactions at around the excitation energy (Ex) of 10 MeV was resolved in individual L = 0, GT states. Excitation strengths were obtained for these GT states. If the R2 value that is defined by the ratio between GT and Fermi unit cross sections is known, the B(GT) values can be determined from the excitation strengths. For the derivation of the R2 value, the “merged analysis” combining the GT strength distribution from the 54Fe(3He,t)54Co study and the half-life from a 54Ni β decay was used, where T=1 isospin symmetry for A=54 isobars was assumed. The GT strengths were compared with a shell-model calculation using the GXPF1 interaction. The final GT states can have the isospin values T = 0, 1, and 2. The isospin T of each GT state observed in the 8.3≤Ex≤12.0 MeV region of the 54Fe(3He,t)54Co spectrum was identified by comparing the excitation strength with that of corresponding M1 state observed in a 54Fe(p,p')54Fe experiment. The B(GT) values of the states identified to have T=2, in particular, are of importance for the calculation of the electron capture rates at the core-collapse stage of presupernovae. The B(GT) strengths were further compared with B(M1) strengths measured in the 54Fe(e,e')54Fe reaction. In the M1 excitation using an electromagnetic probe, isoscalar (IS) and isovector (IV) orbital type operators are active in addition to the IV spin

Functional changes through the usage of 3D-printed transitional prostheses in children.

PubMed

Zuniga, Jorge M; Peck, Jean L; Srivastava, Rakesh; Pierce, James E; Dudley, Drew R; Than, Nicholas A; Stergiou, Nicholas

2017-11-08

There is limited knowledge on the use of 3 D-printed transitional prostheses, as they relate to changes in function and strength. Therefore, the purpose of this study was to identify functional and strength changes after usage of 3 D-printed transitional prostheses for multiple weeks for children with upper-limb differences. Gross manual dexterity was assessed using the Box and Block Test and wrist strength was measured using a dynamometer. This testing was conducted before and after a period of 24 ± 2.61 weeks of using a 3 D-printed transitional prosthesis. The 11 children (five girls and six boys; 3-15 years of age) who participated in the study, were fitted with a 3 D-printed transitional partial hand (n = 9) or an arm (n = 2) prosthesis. Separate two-way repeated measures ANOVAs were performed to analyze function and strength data. There was a significant hand by time interaction for function, but not for strength. Conclusion and relevance to the study of disability and rehabilitation: The increase in manual gross dexterity suggests that the Cyborg Beast 2 3 D-printed prosthesis can be used as a transitional device to improve function in children with traumatic or congenital upper-limb differences. Implications for Rehabilitation Children's prosthetic needs are complex due to their small size, rapid growth, and psychosocial development. Advancements in computer-aided design and additive manufacturing offer the possibility of designing and printing transitional prostheses at a very low cost, but there is limited knowledge on the function of this type of devices. The use of 3D printed transitional prostheses may improve manual gross dexterity in children after several weeks of using it.

Energy levels, oscillator strengths, and transition probabilities for sulfur-like scandium, Sc VI

NASA Astrophysics Data System (ADS)

El-Maaref, A. A.; Abou Halaka, M. M.; Saddeek, Yasser B.

2017-09-01

Energy levels, Oscillator strengths, and transition probabilities for sulfur-like scandium are calculated using CIV3 code. The calculations have been executed in an intermediate coupling scheme using Breit-Pauli Hamiltonian. The present calculations have been compared with the experimental data and other theoretical calculations. LANL code has been used to confirm the accuracy of the present calculations, where the calculations using CIV3 code agree well with the corresponding values by LANL code. The calculated energy levels and oscillator strengths are in reasonable agreement with the published experimental data and theoretical values. We have calculated lifetimes of some excited levels, as well.

The E3Σ1+ (63S1) ← A3Π0+(53P1) transition in CdAr revisited: The spectrum and new analysis of the E3Σ1+ Rydberg state interatomic potential

NASA Astrophysics Data System (ADS)

Urbańczyk, T.; Krośnicki, M.; Kędziorski, A.; Koperski, J.

2018-05-01

Revisited study of the E3Σ1+ (63S1) ← A3Π0+(53P1) transition in CdAr using both theoretical and experimental approach is presented. Systematic detection of the E3Σ1+in,υ' ← A3Π0+,υ″ = 6 transition frequencies with higher accuracy and spectrally narrower laser extended and improved analysis and simulation of the LIF excitation spectrum. More consistent characterization of the E3Σ1+in-Rydberg state inner well using inversed perturbation approach methodology was achieved. Free ← bound transitions in the E3Σ1+in ← A3Π0+,υ″ = 6 excitation were taken into account in the analysis and simulation of the recorded spectrum. The updated spectroscopic characterization of the A3Π0+ state was also revisited.

The E3Σ1+ (63S1)←A3Π0+(53P1) transition in CdAr revisited: The spectrum and new analysis of the E3Σ1+ Rydberg state interatomic potential.

PubMed

Urbańczyk, T; Krośnicki, M; Kędziorski, A; Koperski, J

2018-05-05

Revisited study of the E 3 Σ 1 + (6 3 S 1 )←A 3 Π 0+ (5 3 P 1 ) transition in CdAr using both theoretical and experimental approach is presented. Systematic detection of the E 3 Σ 1 + in ,υ'←A 3 Π 0+ ,υ″=6 transition frequencies with higher accuracy and spectrally narrower laser extended and improved analysis and simulation of the LIF excitation spectrum. More consistent characterization of the E 3 Σ 1 + in -Rydberg state inner well using inversed perturbation approach methodology was achieved. Free←bound transitions in the E 3 Σ 1 + in ←A 3 Π 0+ ,υ″=6 excitation were taken into account in the analysis and simulation of the recorded spectrum. The updated spectroscopic characterization of the A 3 Π 0+ state was also revisited. Copyright © 2018 Elsevier B.V. All rights reserved.

A systematic review of consumer preference for e-cigarette attributes: Flavor, nicotine strength, and type

PubMed Central

Nemati, Mehdi; Zheng, Yuqing

2018-01-01

Objective Systematic review of research examining consumer preference for the main electronic cigarette (e-cigarette) attributes namely flavor, nicotine strength, and type. Method A systematic search of peer-reviewed articles resulted in a pool of 12,933 articles. We included only articles that meet all the selection criteria: (1) peer-reviewed, (2) written in English, and (3) addressed consumer preference for one or more of the e-cigarette attributes including flavor, strength, and type. Results 66 articles met the inclusion criteria for this review. Consumers preferred flavored e-cigarettes, and such preference varied with age groups and smoking status. We also found that several flavors were associated with decreased harm perception while tobacco flavor was associated with increased harm perception. In addition, some flavor chemicals and sweeteners used in e-cigarettes could be of toxicological concern. Finally, consumer preference for nicotine strength and types depended on smoking status, e-cigarette use history, and gender. Conclusion Adolescents could consider flavor the most important factor trying e-cigarettes and were more likely to initiate vaping through flavored e-cigarettes. Young adults overall preferred sweet, menthol, and cherry flavors, while non-smokers in particular preferred coffee and menthol flavors. Adults in general also preferred sweet flavors (though smokers like tobacco flavor the most) and disliked flavors that elicit bitterness or harshness. In terms of whether flavored e-cigarettes assisted quitting smoking, we found inconclusive evidence. E-cigarette users likely initiated use with a cigarette like product and transitioned to an advanced system with more features. Non-smokers and inexperienced e-cigarettes users tended to prefer no nicotine or low nicotine e-cigarettes while smokers and experienced e-cigarettes users preferred medium and high nicotine e-cigarettes. Weak evidence exists regarding a positive interaction between menthol

A systematic review of consumer preference for e-cigarette attributes: Flavor, nicotine strength, and type.

PubMed

Zare, Samane; Nemati, Mehdi; Zheng, Yuqing

2018-01-01

Systematic review of research examining consumer preference for the main electronic cigarette (e-cigarette) attributes namely flavor, nicotine strength, and type. A systematic search of peer-reviewed articles resulted in a pool of 12,933 articles. We included only articles that meet all the selection criteria: (1) peer-reviewed, (2) written in English, and (3) addressed consumer preference for one or more of the e-cigarette attributes including flavor, strength, and type. 66 articles met the inclusion criteria for this review. Consumers preferred flavored e-cigarettes, and such preference varied with age groups and smoking status. We also found that several flavors were associated with decreased harm perception while tobacco flavor was associated with increased harm perception. In addition, some flavor chemicals and sweeteners used in e-cigarettes could be of toxicological concern. Finally, consumer preference for nicotine strength and types depended on smoking status, e-cigarette use history, and gender. Adolescents could consider flavor the most important factor trying e-cigarettes and were more likely to initiate vaping through flavored e-cigarettes. Young adults overall preferred sweet, menthol, and cherry flavors, while non-smokers in particular preferred coffee and menthol flavors. Adults in general also preferred sweet flavors (though smokers like tobacco flavor the most) and disliked flavors that elicit bitterness or harshness. In terms of whether flavored e-cigarettes assisted quitting smoking, we found inconclusive evidence. E-cigarette users likely initiated use with a cigarette like product and transitioned to an advanced system with more features. Non-smokers and inexperienced e-cigarettes users tended to prefer no nicotine or low nicotine e-cigarettes while smokers and experienced e-cigarettes users preferred medium and high nicotine e-cigarettes. Weak evidence exists regarding a positive interaction between menthol flavor and nicotine strength.

Oscillator strengths of selected resonance transitions in neutral sulfur

NASA Technical Reports Server (NTRS)

Beideck, D. J.; Schectman, R. M.; Federman, S. R.; Ellis, D. G.

1994-01-01

Mean lives and branching ratios for the 4s (3)S(sup 0 sub 1) and 4s(double prime) (3)P(sup 0 sub 1, 2) levels of neutral sulfur were determined at the Toledo Heavy Ion Accelerator using beam-foil spectroscopic techniques. The mean lives obtained for the 4s (3)S(sup 0 sub 1) 4s(double prime) (3)P(sup 0 sub 1), and (3)P(sup 0 sub 2) levels, 1.875 +/- 0.094 ns, 2.034 +/- 0.102 ns, and 2.146 +/- 0.129 ns, respectively, represent the most accurate results available to date. Oscillator strengths for the transitions 3p(sup 4)(3)P(sub 2, 1, 0)-4s (3)S(sup 0 sub 1) and 3p(sup 4)(3)P(sub 2, 1, 0)-4s(double prime) (3)P(sup 0 sub 1, 2) were derived from these mean lives together with the measured branching ratios. For comparison with published results which present only multiplet f-values, such f-values were computed from the measured individual line oscillator strengths. The value obtained for the 3p(sup 4)(3)P-4s(sup 3)S(sup 0) multiplet at 1814 A is 0.088 +/- 0.005, in good agreement with the mean of previous experimental measurements and theoretical calculations. With the mean life for the 4s(double prime) 3P(sup 0 sub 0) level set equal to the mean of our determination for the other two 4s(double prime) (3)P(sup 0) levels (a valid assumption for LS coupling conditions, and consistent with the observed equality of the mean lives within the accuracy of our measurement), an oscillator strength for the 1299 A multiplet of 0.121 +/- 0.004 was found. Both results are in good agreement with recent large-scale theoretical calculations that incorporate the effects of configuration interaction.

Isospin symmetry of Tz =±3/2→±1/2 Gamow-Teller transitions in A=41 nuclei

NASA Astrophysics Data System (ADS)

Fujita, Y.; Shimbara, Y.; Adachi, T.; Berg, G. P.; Brown, B. A.; Fujita, H.; Hatanaka, K.; Kamiya, J.; Nakanishi, K.; Sakemi, Y.; Sasaki, S.; Shimizu, Y.; Tameshige, Y.; Uchida, M.; Wakasa, T.; Yosoi, M.

2004-11-01

Under the assumption that isospin T is a good quantum number, isobaric analog states and various analogous transitions are expected in isobars with mass number A . The strengths of Tz =±3/2→±1/2 analogous Gamow-Teller (GT) transitions and analogous M1 transitions within the A=41 isobar quartet are compared in detail. The Tz =+3/2→+1/2 GT transitions from the Jπ = 3/2+ ground state of 41K leading to excited Jπ = 1/2+ , 3/2+ , and 5/2+ states in 41Ca were measured using the ( 3He ,t) charge-exchange reaction. With a high energy resolution of 35 keV , many fragmented states were observed, and the GT strength distribution was determined up to 10 MeV excitation energy ( Ex ) . The main part of the strength was concentrated in the Ex =4 6 MeV region. A shell-model calculation could reproduce the concentration, but not so well details of the strength distribution. The obtained distribution was further compared with two results of 41Ti β decay studying the analogous Tz =-3/2→-1/2 GT strengths. They reported contradicting distributions. One-to-one correspondences of analogous transitions and analog states were assigned up to Ex =6 MeV in the comparison with one of these 41Ti β -decay results. Combining the spectroscopic information of the analog states in 41Ca and 41Sc , the most probable Jπ values were deduced for each pair of analog states. It was found that 5/2+ states carry the main part of the observed GT strength, while much less GT strength was carried by 1/2+ and 3/2+ states. The gross features of the GT strength distributions for each J were similar for the isospin analogous Tz =±3/2→±1/2 transitions, but the details were somewhat different. From the difference of the distributions, isospin-asymmetry matrix elements of ≈8 keV were deduced. The Coulomb displacement energy, which is sensitive to the configuration of states, showed a sudden increase of about 50 keV at the excitation energy of 3.8 MeV . The strengths of several M1 transitions to the

Decreased eIF3e/Int6 expression causes epithelial-to-mesenchymal transition in breast epithelial cells.

PubMed

Gillis, L D; Lewis, S M

2013-08-01

eIF3e/Int6 is a component of the multi-subunit eIF3 complex, which binds directly to the 40S ribosome to facilitate ribosome recruitment to mRNA and hence protein synthesis. Reduced expression of eIF3e/Int6 has been found in up to 37% of human breast cancers, and expression of a truncated mutant version of the mouse eIF3e/Int6 protein leads to malignant transformation of normal mammary cells. These findings suggest that eIF3e/Int6 is a tumor suppressor; however, a recent study has reported that a reduction of eIF3e/Int6 expression in breast cancer cells leads to reduced translation of oncogenes, suggesting that eIF3e/Int6 may in fact have an oncogenic role in breast cancer. To gain a better understanding of the role of eIF3e/Int6 in breast cancer, we have examined the effects of decreased eIF3e/Int6 expression in an immortalized breast epithelial cell line, MCF-10A. Surprisingly, we find that decreased expression of eIF3e/Int6 causes breast epithelial cells to undergo epithelial-to-mesenchymal transition (EMT). We show that EMT induced by a decrease in eIF3e/Int6 expression imparts invasive and migratory properties to breast epithelial cells, suggesting that regulation of EMT by eIF3e/Int6 may have an important role in breast cancer metastasis. Furthermore, we show that reduced eIF3e/Int6 expression in breast epithelial cells causes a specific increase in the expression of the key EMT regulators Snail1 and Zeb2, which occurs at both the transcriptional and post-transcriptional levels. Together, our data indicate a novel role of eIF3e/Int6 in the regulation of EMT in breast epithelial cells and support a tumor suppressor role of eIF3e/Int6.

Relativistic distorted-wave collision strengths for Δn = 0 transitions in the 67 Li-like, F-like and Na-like ions with 26 ≤ Z ≤ 92

DOE PAGES

Fontes, Christopher J.; Zhang, Hong Lin

2017-01-01

We calculated relativistic distorted-wave collision strength for all possible Δn=0 transitions, where n denotes the valence shell of the ground level, in the 67 Li-like, F-like and Na-like ions with Z in the range 26 ≤ Z ≤92. This choice produces 3 transitions with n=2 in the Li-like and F-like ions, and 10 transitions with n=3 in the Na-like ions. Moreover, for the Li-like and F-like ions, the calculations were made for the six final, or scattered, electron energies E'=0.008,0.04,0.10,0.21,0.41, and 0.75, where E' is in units of Zmore » $$2\\atop{eff}$$ Ry with Z eff = Z- 1.66 for Li-like ions and Z eff= Z- 6.667 for F-like ions. For the Na-like ions, the calculations were made for the six final electron energies E'=0.0025,0.015,0.04,0.10,0.21, and 0.40, with Z eff = Z- 8.34. In the present calculations, an improved “top-up” method, which employs relativistic plane waves, was used to obtain the high partial-wave contribution for each transition, in contrast to the partial-relativistic Coulomb–Bethe approximation used in previous works by Zhang, Sampson and Fontes [H.L. Zhang, D.H. Sampson, C.J. Fontes, At. Data Nucl. Data Tables 44 (1990) 31; H.L. Zhang, D.H. Sampson, C.J. Fontes, At. Data Nucl. Data Tables 48 (1991) 25; D.H. Sampson, H.L. Zhang, C.J. Fontes, At. Data Nucl. Data Tables 44 (1990) 209]. In those previous works, collision strengths were also provided for Li-, F- and Na-like ions, but for a more comprehensive set of transitions. Finally, the collision strengths covered in the present work should be more accurate than the corresponding data given in those previous works and are presented here to replace those earlier results.« less

E1 and M1 strength functions at low energy

NASA Astrophysics Data System (ADS)

Schwengner, Ronald; Massarczyk, Ralph; Bemmerer, Daniel; Beyer, Roland; Junghans, Arnd R.; Kögler, Toni; Rusev, Gencho; Tonchev, Anton P.; Tornow, Werner; Wagner, Andreas

2017-09-01

We report photon-scattering experiments using bremsstrahlung at the γELBE facility of Helmholtz-Zentrum Dresden-Rossendorf and using quasi-monoenergetic, polarized γ beams at the HIγS facility of the Triangle Universities Nuclear Laboratory in Durham. To deduce the photoabsorption cross sections at high excitation energy and high level density, unresolved strength in the quasicontinuum of nuclear states has been taken into account. In the analysis of the spectra measured by using bremsstrahlung at γELBE, we perform simulations of statistical γ-ray cascades using the code γDEX to estimate intensities of inelastic transitions to low-lying excited states. Simulated average branching ratios are compared with model-independent branching ratios obtained from spectra measured by using monoenergetic γ beams at HIγS. E1 strength in the energy region of the pygmy dipole resonance is discussed in nuclei around mass 90 and in xenon isotopes. M1 strength in the region of the spin-flip resonance is also considered for xenon isotopes. The dipole strength function of 74Ge deduced from γELBE experiments is compared with the one obtained from experiments at the Oslo Cyclotron Laboratory. The low-energy upbend seen in the Oslo data is interpreted as M1 strength on the basis of shell-model calculations.

Spin dependence of intra-ground-state-band E2 transitions in the SU(3) limit of the sdg interacting boson model

NASA Astrophysics Data System (ADS)

Long, G. L.; Ji, H. Y.

1998-04-01

B(E2, L+2-->L) transitions in the sdg interacting boson model SU(3) limit are studied with a general E2 transition operator. Analytical expressions are obtained using a group theoretic method. It is found that when using transition operators of the form (d†g~+g†d~)2 or (g†g~)2, the B(E2, L+2-->L) values in the ground-state band have an L(L+3) dependent term. As L increases, the B(E2) values can be larger than the rigid rotor model value. Application to 236,238U is discussed.

Effective collision strengths for fine-structure forbidden transitions among the 3s^23p^3 levels of K V

NASA Astrophysics Data System (ADS)

Bell, Kenneth; Wilson, Nigel

2001-05-01

Electron temperatures and densities are difficult to determine in many astrophysical plasmas. However, it is well known that diagnostics on forbidden line intensity ratios for ions in the phosphorous isoelectronic sequence are of great importance in astrophysics, particularly for nebulae. A key element in the analysis is highly accurate atomic data. In this work we extend the earlier calculations of Butler, Zeippen and Le Bourlot (Astron. Astrophys. 203 189 (1988)) on electron scattering by K v. We have obtained effective collision strengths for a wide range of electron temperatures using the R-matrix method. Twenty-two LS target eigenstates are included in the expansion of the total wavefunction, consisting of the seven n=3 states with configuration 3s^23p^3 and 3s3p^4, twelve n=3 states with configuration 3s^23p^23d, and three n=4 states with configuration 3s^23p^24s. The fine-structure collision strengths have been obtained by transforming to a jj-coupling scheme using the JAJOM program of Saraph (Comp. Phys. Commun. 15 247 (1978)) and have been determined at a sufficiently fine energy mesh to delineate properly the resonance structure. Results for both collision strengths and for effective collision strengths will be presented at the conference and comparison will be made with the earlier work.

Effect of strain on structure and charge order transitions in epitaxial Bi0.4Ca0.6MnO3 films on perovskite (001) and (011) substrates

NASA Astrophysics Data System (ADS)

Kim, Dae Ho; Christen, Hans M.; Varela, Maria; Lee, Ho Nyung; Lowndes, Douglas H.

2006-05-01

The effect of epitaxial strain on the charge order (CO) transition in Bi0.4Ca0.6MnO3 films was studied by varying the strain's strength and symmetry via the use of SrTiO3 and LaAlO3 substrates having different crystallographic orientations. The film on pseudocubic (001) LaAlO3, under symmetric compressive strain, exhibits a clear CO transition. In the film on a (001) SrTiO3 substrate, under symmetric tensile strain, highly segregated line-shaped features in the Bi distribution are seen in Z-contrast scanning transmission microscopy, accompanied by a strongly broadened CO transition. The asymmetric tensile stress on (011) SrTiO3 results in an apparent compressive strain state with a deviation from tetragonality (i.e., γ ≠90°), accompanied by the sharpest CO transition. These comparisons illustrate the importance of considering both the strength and symmetry of epitaxial strain.

Effect of transition metal impurities on the strength of grain boundaries in vanadium

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

Wu, Xuebang; Kong, Xiang-Shan; You, Yu-Wei

2016-09-07

Effects of 3d (Ti-Ni), 4d (Zr-Pd), and 5d (Hf-Pt) transition metal impurities on strength of two representative vanadium grain boundaries (GBs), symmetric Σ3(111) and asymmetric Σ5(210), were studied by first-principles calculations within the framework of the Rice-Wang thermodynamic model and within the computational tensile test. The desirable elements to increase the GB cohesion were predicted based on their segregation and strengthening behaviors across the different GB sites. It reveals that the elements Ti, Zr, Hf, Nb, and Ta are good choices for the GB cohesion enhancers. In addition, the GB strengthening by solutes is sensitive to the GB structures. Themore » elements Cr, Mn, Fe, Co, and Ni decrease the GB strength of the Σ3(111) GB but they can increase the cohesion of the Σ5(210) GB. Furthermore, the origin of Ti-induced change of the GB strength was uncovered by analyzing the atomic bonds and electronic structures as well as the tensile strength. This work provides a theoretical guidance to screen promising alloying elements in V-based materials with improved resistance to GB decohesion and also helps us to understand the formation mechanism of Ti-rich precipitates in the V-Cr-Ti alloys under neutron or ion irradiation environments.« less

High field induced magnetic transitions in the Y0.7E r0.3F e2D4.2 deuteride

NASA Astrophysics Data System (ADS)

Paul-Boncour, V.; Guillot, M.; Isnard, O.; Hoser, A.

2017-09-01

The influence of the partial Er for Y substitution on the crystal structure and magnetic properties of YF e2D4.2 has been investigated by high field magnetization and neutron diffraction experiments. Y0.7E r0.3F e2D4.2 compound crystallizes in the same monoclinic structure as YF e2D4.2 described in P c (P1c1) space group with D atoms located in 18 different tetrahedral interstitial sites. A cell volume contraction of 0.6% is observed upon Er substitution, inducing large modification of the magnetic properties. Electronic effect of D insertion as well as lowering of crystal symmetry are important factors determining the magnetic properties of Fe sublattice, which evolves towards more delocalized behavior and modifying the Er-Fe exchange interactions. In the ground state, the Er and Fe moments are arranged ferrimagnetically within the plane perpendicular to the monoclinic b axis and with average moments mEr=6.4 (3 ) μBEr-1 and mFe=2.0 (1 ) μBFe-1 at 10 K. Upon heating, mEr decreases progressively until TEr=55 K . Between 55 K and 75 K, the Fe sublattice undergoes a first-order ferromagnetic-antiferromagnetic (FM-AFM) transition with a cell volume contraction due to the itinerant metamagnetic behavior of one Fe site. In the AFM structure, mFe decreases until the Néel temperature TN=125 K . At high field, two different types of field induced transitions are observed. The Er moments become parallel to the Fe one and saturates to the E r3 + free ion value, leading to an unusual field induced FM arrangement at a transition field BTrans of only 78 kG below 30 K. Then above TM0=66 K , an AFM-FM transition of the Fe sublattice, accompanied by a cell volume increase is observed. BTrans increases linearly versus temperature and with a larger d BTrans/d T slope than for YF e2D4.2 . This has been explained by the additional contribution of Er induced moments above BTrans.

Core excitation effects on oscillator strengths for transitions in four electron atomic systems

NASA Astrophysics Data System (ADS)

Chang, T. N.; Luo, Yuxiang

2007-06-01

By including explicitly the electronic configurations with two and three simultaneously excited electronic orbital, we have extended the BSCI (B-spline based configuration interaction) method [1] to estimate directly the effect of inner shell core excitation to oscillator strengths for transitions in four-electron atomic systems. We will present explicitly the change in oscillator strengths due to core excitations, especially for transitions involving doubly excited states and those with very small oscillator strengths. The length and velocity results are typically in agreement better than 1% or less. [1] Tu-nan Chang, in Many-body Theory of Atomic Structure and Photoionization, edited by T. N. Chang (World Scientific, Singapore, 1993), p. 213-47; and T. N. Chang and T. K. Fang, Elsevier Radiation Physics and Chemistry 70, 173-190 (2004).

Absence of quantum anomalous Hall state in 4 d transition-metal-doped B i2S e3 : An ab initio study

NASA Astrophysics Data System (ADS)

Deng, Bei; Liu, Feng; Zhu, Junyi

2017-11-01

The realization of insulating ferromagnetic states in topological insulator (TI) systems, with sufficiently high Curie temperatures (TC) and large magnetically induced gaps, has been the key bottleneck towards the realization of the quantum anomalous Hall effect (QAHE). Despite the limited reports on 3 d or 4 f transition-metal (TM)-doped B i2S e3 , there remains a lack of systematic studies on 4 d TMs, which may be potential candidates since the atomic sizes of 4 d TMs and that of Bi are similar. Here, we report a theoretical work that probes the magnetic behaviors of the 4 d TM-doped B i2S e3 system. We discovered that among the 4 d TMs, Nb and Mo can create magnetic moments of 1.76 and 2.96 μ B in B i2S e3 , respectively. While Mo yields a stable gapless antiferromagnetic ground state, Nb favors a strong ferromagnetic order, with the magnetic coupling strength (TC) ˜6 times of that induced by the traditional Cr impurity. Yet, we found that Nb is still unfavorable to support the QAH state in B i2S e3 because of the reduced correlation in the t2 g band that gives a gapless character. This rationale is not only successful in interpreting why Nb, the strongest candidate among 4 d TMs for achieving ferromagnetism in B i2S e3 , actually cannot lead to QAHE in the B i2S e3 system even with the assistance of codoping but also is particularly important to fully understand the mechanism of acquisition of insulating ferromagnetic states inside TI. On the other hand, we discovered that Mo-doped B i2S e3 favors strong antiferromagnetic states and may lead to superconducting states.

Etudes diélectriques de la transition ferroélectrique induite par application d'un champ électrique dans les céramiques PbMg{1/3}Nb{2/3}O3 (PMN)

NASA Astrophysics Data System (ADS)

Chabin, M.; Malki, M.; Husson, E.; Morell, A.

1994-07-01

The evolution of the dielectric permittivity and loss factor under an external applied electric field has been studied in PbMg{1/3}Nb{2/3}O3 ceramics between 80 and 420 K. For a threshold field of 4 kV.cm^{-1}, it is possible to induce a ferroelectric transition from the average cubic phase to a macroscopically polar phase. The poling and depoling temperatures depend on the various combinations of thermal treatments and on the applied field strength. The transition between the nanopolar state and the macropolar state is discussed L'évolution de la permittivité diélectrique et du facteur de pertes diélectriques sous un champ électrique extérieur a été étudiée dans des céramiques de PbMg{1/3}Nb{2/3}O3 enre 80 et 420 K. Pour un champ de seuil de 4 kV.cm^{-1} il est possible d'induire une transition ferroélectrique de la phase cubique moyenne en une phase macroscopiquement polaire. Les températures de polarisation et de dépolarisation dépendent des différentes combinaisons de traitements thermiques et de la valeur du champ appliqué. La transition entre la phase constituée de nanodomaines polaires et la phase constituée de macrodomaines polaires est discutée.

High-resolution study of Gamow-Teller transitions in the 47Ti(3He,t)47V reaction

NASA Astrophysics Data System (ADS)

Ganioǧlu, E.; Fujita, H.; Fujita, Y.; Adachi, T.; Algora, A.; Csatlós, M.; Deaven, J. M.; Estevez-Aguado, E.; Guess, C. J.; Gulyás, J.; Hatanaka, K.; Hirota, K.; Honma, M.; Ishikawa, D.; Krasznahorkay, A.; Matsubara, H.; Meharchand, R.; Molina, F.; Okamura, H.; Ong, H. J.; Otsuka, T.; Perdikakis, G.; Rubio, B.; Scholl, C.; Shimbara, Y.; Susoy, G.; Suzuki, T.; Tamii, A.; Thies, J. H.; Zegers, R. G. T.; Zenihiro, J.

2013-01-01

Given the importance of Gamow-Teller (GT) transitions in nuclear structure and astrophysical nuclear processes, we have studied Tz=+3/2→+1/2, GT transitions starting from the 47Ti nucleus in the (3He,t) charge-exchange reaction at 0∘ and at an intermediate incident energy of 140 MeV/nucleon. The experiments were carried out at the Research Center for Nuclear Physics (RCNP), Osaka, using the high-resolution facility with a high-dispersion beam line and the Grand-Raiden spectrometer. With an energy resolution of 20 keV, individual GT transitions were observed and GT strength was derived for each state populated up to an excitation energy (Ex) of 12.5 MeV. The GT strength was widely distributed from low excitation energy up to 12.5 MeV, where we had to stop the analysis because of the high level density. The distribution of the GT strengths was compared with the results of shell model calculations using the GXPF1 interaction. The calculations could reproduce the experimental GT distributions well. The GT transitions from the ground state of 47Ti and the M1 transitions from the isobaric analog state in 47V to the same low-lying states in 47V are analogous. It was found that the ratios of GT transition strengths to the ground state, the 0.088-MeV state, and the 0.146-MeV state are similar to the ratios of the strengths of the analogous M1 transitions from the isobaric analog state (IAS) to these states. The measured distribution of the GT strengths was also compared with those starting from the Tz=+3/2 nucleus 41K to the Tz=+1/2 nucleus 41Ca.

Oscillator strengths and branching fractions of 4d75p-4d75s Rh II transitions

NASA Astrophysics Data System (ADS)

Bouazza, Safa

2017-01-01

This work reports semi-empirical determination of oscillator strengths, transition probabilities and branching fractions for Rh II 4d75p-4d75s transitions in a wide wavelength range. The angular coefficients of the transition matrix, beforehand obtained in pure SL coupling with help of Racah algebra are transformed into intermediate coupling using eigenvector amplitudes of these two configuration levels determined for this purpose; The transition integral was treated as free parameter in the least squares fit to experimental oscillator strength (gf) values found in literature. The extracted value: <4d75s|r1|4d75p> =2.7426 ± 0.0007 is slightly smaller than that computed by means of ab-initio method. Subsequently to oscillator strength evaluations, transition probabilities and branching fractions were deduced and compared to those obtained experimentally or through another approach like pseudo-relativistic Hartree-Fock model including core-polarization effects.

A new Morse-oscillator based Hamiltonian for H 3+: Calculation of line strengths

NASA Astrophysics Data System (ADS)

Jensen, Per; Špirko, V.

1986-07-01

In two recent publications [V. Špirko, P. Jensen, P. R. Bunker, and A. Čejchan, J. Mol. Spectrosc.112, 183-202 (1985); P. Jensen, V. Špirko, and P. R. Bunker, J. Mol. Spectrosc.115, 269-293 (1986)], we have described the development of Morse oscillator adapted rotation-vibration Hamiltonians for equilateral triangular X3 and Y2X molecules, and we have used these Hamiltonians to calculate the rotation-vibration energies for H 3+ and its X3+ and Y2X+ isotopes from ab initio potential energy functions. The present paper presents a method for calculating rotation-vibration line strengths of H 3+ and its isotopes using an ab initio dipole moment function [G. D. Carney and R. N. Porter, J. Chem. Phys.60, 4251-4264 (1974)] together with the energies and wave-functions obtained by diagonalization of the Morse oscillator adapted Hamiltonians. We use this method for calculating the vibrational transition moments involving the lowest vibrational states of H 3+, D 3+, H 2D +, and D 2H +. Further, we calculate the line strengths of the low- J transitions in the rotational spectra of H 3+ in the vibrational ground state and in the ν1 and ν2 states. We hope that the calculations presented will facilitate the search for further rotation-vibration transitions of H 3+ and its isotopes.

Relativistic distorted-wave collision strengths for the 49 Δn=0 optically allowed transitions with n=2 in the 67 B-like ions with 26≤Z≤92

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

Fontes, Christopher J., E-mail: cjf@lanl.gov; Zhang, Hong Lin

2014-05-15

Relativistic distorted-wave collision strengths have been calculated for the 49 Δn=0 optically allowed transitions with n=2 in the 67 B-like ions with nuclear charge number Z in the range 26≤Z≤92. The calculations were made for the four final, or scattered, electron energies E{sup ′}=0.20, 0.42, 0.80, and 1.40, where E{sup ′} is in units of Z{sub eff}{sup 2} Ry with Z{sub eff}=Z−3.33. In the present calculations, an improved “top-up” method, which employs relativistic plane waves, was used to obtain the high partial-wave contribution for each transition, in contrast to the partial-relativistic Coulomb–Bethe approximation used in previous work by Zhang andmore » Sampson [H.L. Zhang and D.H. Sampson, At. Data Nucl. Data Tables 56 (1994) 41]. In that earlier work, collision strengths were also provided for B-like ions, but for a more comprehensive data set consisting of all 105 Δn=0 transitions, six scattered energies and the 85 ions with Z in the range 8≤Z≤92. The collision strengths covered in the present work should be more accurate than the corresponding data given by Zhang and Sampson [H.L. Zhang and D.H. Sampson, At. Data Nucl. Data Tables 56 (1994) 41] and are presented here to replace those earlier results.« less

New Accurate Oscillator Strengths and Electron Excitation Collision Strengths for N1

NASA Technical Reports Server (NTRS)

Tayal, S. S.

2006-01-01

The nonorthogonal orbitals technique in a multiconfiguration Hartree-Fock approach is used to calculate oscillator strengths and transition probabilities of N(I) lines. The relativistic effects are allowed by means of Breit-Pauli operators. The length and velocity forms of oscillator strengths show good agreement for most transitions. The B-spline R-matrix with pseudostates approach has been used to calculate electron excitation collision strengths and rates. The nonorthogonal orbitals are used for an accurate description of both target wave functions and the R-matrix basis functions. The 24 spectroscopic bound and autoionizing states together with 15 pseudostates are included in the close-coupling expansion. The collision strengths for transitions between fine-structure levels are calculated by transforming the LS-coupled K-matrices to K-matrices in an intermediate coupling scheme. Thermally averaged collision strengths have been determined by integrating collision strength over a Maxwellian distribution of electron energies over a temperature range suitable for the modeling of astrophysical plasmas. The oscillator strengths and thermally averaged collision strengths are presented for transitions between the fine-structure levels of the 2s(sup 2)p(sup 3) (sup 4)S(sup 0), (sup 2)D(sup 0), (sup 2)P(sup 0), 2s2p(sup 4) (sup 4)P, 2s(sup 2)2p(sup 2)3s (sup 4)P, and (sup 2)P terms and from these levels to the levels of the 2s(sup 2)2p(sup 2)3p (sup 2)S(sup 0), (sup 4)D(sup 0), (sup 4)P(sup 0), (sup 4)S(sup 0), (sup 2)D(sup 0), (sup 2)P(sup 0),2s(sup 2)2p(sup 2)3s(sup 2)D, 2s(sup 2)2p(sup 2)4s(sup 4)P, (sup 2)P, 2s(sup 2)2p(sup 2)3d(sup 2)P, (sup 4)F,(sup 2)F,(sup 4)P, (sup 4)D, and (sup 2)D terms. Thermally averaged collision strengths are tabulated over a temperature range from 500 to 50,000 K.

Level Energies, Oscillator Strengths and Lifetimes for Transitions in Pb IV

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

Colon, C.; Alonso-Medina, A.; Zanon, A.

2008-10-22

Oscillator strengths for several lines of astrophysical interest arising from some configurations and some levels radiative lifetimes of Pb IV have been calculated. These values were obtained in intermediate coupling (IC) and using ab initio relativistic Hartree-Fock calculations. We use for the IC calculations the standard method of least square fitting of experimental energy levels by means of computer codes from Cowan. Transition Probabilities and oscillator strengths obtained, although in general agreement with the rare experimental data, do present some noticeable discrepancies that are studied in the text.

Refractive index effects on the oscillator strength and radiative decay rate of 2,3-diazabicyclo[2.2.2]oct-2-ene.

PubMed

Mohanty, Jyotirmayee; Nau, Werner M

2004-01-01

The photophysical properties of 2,3-diazabicyclo[2.2.2]oct-2-ene (DBO) were determined in 15 solvents, two supramolecular hosts (cucurbit[7]uril and beta-cyclodextrin) as well as in the gas phase. The oscillator strength and radiative decay rate of DBO as a function of refractive index i.e. polarizability have been analyzed. The oscillator strength increases by a factor of 10 upon going from the gas phase to the most polarizable carbon disulfide, while the corresponding radiative decay rates increase by a factor of 40. There is a good empirical correlation between the oscillator strength of the weakly allowed n,pi* transition of DBO and the reciprocal bulk polarizability, which can be employed to assess the polarizability of unknown microheterogeneous environments. A satisfactory correlation between the radiative decay rate and the square of the refractive index is also found, as previously documented for chromophores with allowed transitions. However, the correlation improves significantly when the oscillator strength is included in the correlation, which demonstrates the importance of this factor in the Strickler-Berg equation for chromophores with forbidden or weakly allowed transitions, for which the oscillator strength may be strongly solvent dependent. The radiative decay rate of DBO in two supramolecular assemblies has been determined, confirming the very low polarizability inside the cucurbituril cavity, in between perfluorohexane and the gas phase. The fluorescence quantum yield of DBO in the gas phase has been remeasured (5.1 +/- 0.5%) and was found to fall one full order of magnitude below a previously reported value.

Effects of grain size on the strength and ductility of Ni sub 3 Al and Ni sub 3 Al + boron

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

Viens, D.V.; Weihs, T.P.; Baker, I.

Tensile and compression experiments have been performed on Ni{sub 3}Al and on Ni{sub 3}Al + B at 77K to 1023K at 1 {times} 10{sup {minus}4}s{sup {minus}1}. At low temperatures yielding occurs discontinuously and the yield strength obeys the relationship {sigma}{sub y} = {sigma}{sub i} + kd{sup {minus}3/4} where {sigma}{sub i} and k are constants. Grain refinement has little effect on the ductility of the binary alloy, but leads to a brittle to ductile transition in the alloy containing boron. At high temperatures, grain refinement weakens the material, owing to grain boundary sliding. Dynamic recrystalization occurs and leads to another brittlemore » to ductile transition upon refining the grains. Under all conditions investigated, fracture occurs intergranularly. An analysis based upon a work-hardening model is given for the d{sup {minus}3/4} dependence of the yield strength at low temperatures.« less

Luminescence Anisotropy and Thermal Effect of Magnetic and Electric Dipole Transitions of Cr3+ Ions in Yb:YAG Transparent Ceramic.

PubMed

Tang, Fei; Ye, Honggang; Su, Zhicheng; Bao, Yitian; Guo, Wang; Xu, Shijie

2017-12-20

In this article, we present an in-depth optical study on luminescence spectral features and the thermal effect of the magnetic dipole (MD) transitions (e.g., the R lines of 2 E → 4 A 2 ) and the associated electric dipole transitions (e.g., phonon-induced sidebands of the R lines) of Cr 3+ ions in ytterbium-yttrium aluminum garnet polycrystalline transparent ceramic. The doubly split R lines predominately due to the doublet splitting of the 2 E level of the Cr 3+ ion in an octahedral crystal field are found to show a very large anisotropy in both emission intensity and thermal broadening. The large departure from the intensity equality between them could be interpreted in terms of large difference in coupling strength with phonons for the doubly split states of the 2 E level. For the large anisotropy in thermal broadening, very different effective Debye temperatures for the two split states may be responsible for it. Besides the 2 E excited state, the higher excited states, for example, 4 T 1 and 4 T 2 of the Cr 3+ ion, also exhibit a very large inequality in coupling strength with phonons at room temperature. By examining the Stokes phonon sidebands of the MD R lines at low temperatures with the existing ion-phonon coupling theory, we reveal that they indeed carry fundamental information of phonons. For example, their broad background primarily reflects Debye density of states of acoustic phonons. These new results significantly enrich our existing understanding on interesting but challenging luminescence mechanisms of ion-phonon coupling systems.

A measurement of the vibrational band strength for the v3 band of the HO2 radical

NASA Technical Reports Server (NTRS)

Zahniser, M. S.; Stanton, A. C.

1984-01-01

Laboratory measurements of the v(3) band strength of HO2 using a tunable diode laser to measure the absorption strength of a vibration-rotation line in the P branch near 1080/cm are reported. The HO2 is generated in a discharge-flow system by reaction of fluorine atoms with excess H2O2: F + H2O2 - HO2 + HF. The HO2 concentration is determined from measurements of F-atom concentrations using both chemical titration with Cl2 and tunable diode laser absorption by the F-atom spin-orbit transition near 404/cm. The experimental data are consistent with a value of k(3) = (1.6 + or - 0.3) x 10 to the 12th cu cm/s and a ratio k(4)/k(1) = 1.0 + or - 0.4. The line strength for the 6(15) - 7(16)F(1) transition is 2.9 x 10 to the -21 sq cm/molecule/cm, which corresponds to a v(3) band strength of 35 + or - 9/sq cm/(STP atm). This value is a factor of 1.6 to 6 lower than previous ab initio calculations.

Oscillator Strengths and Predissociation Widths for Rydberg Transitions in Carbon Monoxide

NASA Technical Reports Server (NTRS)

Federman, Steven R.; Sheffer, Y.; Eidelsberg, Michele; Lemaire, Jean-Louis; Fillion, Jean-Hugues; Rostas, Francois; Ruiz, J.

2006-01-01

CO is used as a probe of astronomical environments ranging from planetary atmospheres and comets to interstellar clouds and the envelopes surrounding stars near the end of their lives. One of the processes controlling the CO abundance and the ratio of its isotopomers is photodissociation. Accurate oscillator strengths for Rydberg transitions are needed for modeling this process. Absorption bands were analyzed by synthesizing the profiles with codes developed independently in Meudon and Toledo. Each synthetic spectrum was adjusted to match the experimental one in a non-linear least-squares fitting procedure with the band oscillator strength, the line width (instrumental and predissociation.

E-cigarette puffing patterns associated with high and low nicotine e-liquid strength: effects on toxicant and carcinogen exposure.

PubMed

Cox, Sharon; Kośmider, Leon; McRobbie, Hayden; Goniewicz, Maciej; Kimber, Catherine; Doig, Mira; Dawkins, Lynne

2016-09-20

Contrary to intuition, use of lower strength nicotine e-liquids might not offer reduced health risk if compensatory puffing behaviour occurs. Compensatory puffing (e.g. more frequent, longer puffs) or user behaviour (increasing the wattage) can lead to higher temperatures at which glycerine and propylene glycol (solvents used in e-liquids) undergo decomposition to carbonyl compounds, including the carcinogens formaldehyde and acetaldehyde. This study aims to document puffing patterns and user behaviour associated with using high and low strength nicotine e-liquid and associated toxicant/carcinogen exposure in experienced e-cigarette users (known as vapers herein). A counterbalanced repeated measures design. Non-tobacco smoking vapers; have used an e-cigarette for ≥3 months; currently using nicotine strength e-liquid ≥12mg/mL and a second or third generation device. This study will measure puffing patterns in vapers whilst they use high and low strength nicotine e-liquid under fixed and user-defined settings, each for a week. The 4 counterbalanced conditions are: i) low strength (6mg/mL), fixed settings; ii) low strength user-defined settings; iii) high strength (18mg/mL) fixed settings; iv) high strength user-defined settings. Biomarkers of exposure to toxicants and carcinogens will be measured in urine. In the second phase of this study, toxicant yields will be measured in aerosol generated using a smoking machine operated to replicate the puffing behaviours of each participant. i) Puffing patterns (mean puff number, puff duration, inter-puff interval and mL of liquid consumed) and user behaviour (changes to device settings: voltage and air-flow) associated with using high and low strength nicotine e-liquid. ii) Toxicant/carcinogen exposure associated with the puffing patterns/device settings used by our participants. i) Subjective effects. ii) comparisons with toxicant exposure from tobacco smoke (using documented evidence) and with recommended safety limits

Determination of the Oscillator Strengths for the Third and Fourth Vibrational Overtone Transitions in Simple Alcohols

NASA Astrophysics Data System (ADS)

Wallberg, Jens; Kjaergaard, Henrik G.

2017-06-01

Absolute measurements of the weak transitions require sensitive spectroscopic techniques. With our recently constructed pulsed cavity ring down (CRD) spectrometer, we have recorded the third and fourth vibrational overtone of the OH stretching vibration in a series of simple alcohols: methanol (MeOH), ethanol (EtOH), 1-propanol (1-PrOH), 2-propanol (2-PrOH) and tert-butanol (tBuOH). The CRD setup (in a flow cell configuration) is combined with a conventional FTIR spectrometer to determine the partial pressure of the alcohols from the fundamental transitions of the OH-stretching vibration. The oscillator strengths of the overtone transitions are determined from the integrated absorbances of the overtone spectra and the partial pressures. Furthermore, the oscillator strengths were calculated using vibrational local mode theory with energies and dipole moments calculated at CCSD(T)/aug-cc-pVTZ level of theory. We find a good agreement between the observed and calculated oscillator strengths across the series of alcohols.

Attosecond sublevel beating and nonlinear dressing on the 3d-to-5p and 3p-to-5s core-transitions at 91.3 eV and 210.4 eV in krypton.

PubMed

Seres, Enikoe; Seres, Jozsef; Namba, Shinichi; Afa, John; Serrat, Carles

2017-12-11

Applying extreme ultraviolet (XUV) transient absorption spectroscopy, the dynamics of the two laser dressed transitions 3d 5/2 -to-5p 3/2 and 3p 3/2 -to-5s 1/2 at photon energies of 91.3 eV and 210.4 eV were examined with attosecond temporal resolution. The dressing process was modeled with density matrix equations which are found to describe very accurately both the experimentally observed transmission dynamics and the linear and nonlinear dressing oscillations at 0.75 PHz and 1.5 PHz frequencies. Furthermore, using Fourier transform XUV spectroscopy, quantum beats from the 3d 5/2 -3d 3/2 and 3p 3/2 -3p 1/2 sublevels at 0.3 PHz and 2.0 PHz were experimentally identified and resolved.

New Accurate Oscillator Strengths and Electron Excitation Collision Strengths for N I

NASA Astrophysics Data System (ADS)

Tayal, S. S.

2006-03-01

The nonorthogonal orbitals technique in a multiconfiguration Hartree-Fock approach is used to calculate oscillator strengths and transition probabilities of N I lines. The relativistic effects are allowed by means of Breit-Pauli operators. The length and velocity forms of oscillator strengths show good agreement for most transitions. The B-spline R-matrix with pseudostates approach has been used to calculate electron excitation collision strengths and rates. The nonorthogonal orbitals are used for an accurate description of both target wave functions and the R-matrix basis functions. The 24 spectroscopic bound and autoionizing states together with 15 pseudostates are included in the close-coupling expansion. The collision strengths for transitions between fine-structure levels are calculated by transforming the LS-coupled K-matrices to K-matrices in an intermediate coupling scheme. Thermally averaged collision strengths have been determined by integrating collision strengths over a Maxwellian distribution of electron energies over a temperature range suitable for the modeling of astrophysical plasmas. The oscillator strengths and thermally averaged collision strengths are presented for transitions between the fine-structure levels of the 2s22p3 4So, 2Do, 2Po, 2s2p4 4P, 2s22p23s 4P, and 2P terms and from these levels to the levels of the 2s22p23p 2So, 4Do, 4Po, 4So, 2Do, 2Po, 2s22p23s 2D, 2s22p24s 4P, 2P, 2s22p23d 2P, 4F, 2F, 4P, 4D, and 2D terms. Thermally averaged collision strengths are tabulated over a temperature range from 500 to 50,000 K.

Analysis of the E2 transitions for /sup 3/H-/alpha/ cluster states of /sup 7/Li by the resonating group method

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

Xu Pu; Zhao Xuan; Zeng Fanan

1989-07-01

It is suggested that the ground state and the 1st, 2nd, and 3rd excited states of /sup 7/Li are /sup 3/H-/alpha/ cluster-structure states. Using the resonating group method (RGM), the eigenvalues and eigenfunctions of these states as well as the reduced E2 transition probabilities between these states are calculated and are consistent with the experimental values. The results show that the RGM is much better than the harmonic oscillator model used by Bernheim /ital et/ /ital al/. in predicting the E2 transition rates.

Finite-size scaling with respect to interaction and disorder strength at the many-body localization transition

NASA Astrophysics Data System (ADS)

Kudo, Kazue; Deguchi, Tetsuo

2018-06-01

We present a finite-size scaling for both interaction and disorder strengths in the critical regime of the many-body localization (MBL) transition for a spin-1/2 X X Z spin chain with a random field by studying level statistics. We show how the dynamical transition from the thermal to MBL phase depends on interaction together with disorder by evaluating the ratio of adjacent level spacings, and thus, extend previous studies in which interaction coupling is fixed. We introduce an extra critical exponent in order to describe the nontrivial interaction dependence of the MBL transition. It is characterized by the ratio of the disorder strength to the power of the interaction coupling with respect to the extra critical exponent and not by the simple ratio between them.

Fine-structure calculations of energy levels, oscillator strengths, and transition probabilities for sulfur-like iron, Fe XI

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

Abou El-Maaref, A., E-mail: aahmh@hotmail.com; Ahmad, Mahmoud; Allam, S.H.

Energy levels, oscillator strengths, and transition probabilities for transitions among the 14 LS states belonging to configurations of sulfur-like iron, Fe XI, have been calculated. These states are represented by configuration interaction wavefunctions and have configurations 3s{sup 2}3p{sup 4}, 3s3p{sup 5}, 3s{sup 2}3p{sup 3}3d, 3s{sup 2}3p{sup 3}4s, 3s{sup 2}3p{sup 3}4p, and 3s{sup 2}3p{sup 3}4d, which give rise to 123 fine-structure energy levels. Extensive configuration interaction calculations using the CIV3 code have been performed. To assess the importance of relativistic effects, the intermediate coupling scheme by means of the Breit–Pauli Hamiltonian terms, such as the one-body mass correction and Darwin term,more » and spin–orbit, spin–other-orbit, and spin–spin corrections, are incorporated within the code. These incorporations adjusted the energy levels, therefore the calculated values are close to the available experimental data. Comparisons between the present calculated energy levels as well as oscillator strengths and both experimental and theoretical data have been performed. Our results show good agreement with earlier works, and they might be useful in thermonuclear fusion research and astrophysical applications. -- Highlights: •Accurate atomic data of iron ions are needed for identification of solar corona. •Extensive configuration interaction wavefunctions including 123 fine-structure levels have been calculated. •The relativistic effects by means of the Breit–Pauli Hamiltonian terms are incorporated. •This incorporation adjusts the energy levels, therefore the calculated values are close to experimental values.« less

Relative Band Oscillator Strengths for Carbon Monoxide: Alpha (1)Pi-Chi (1)Sigma(+) Transitions

NASA Technical Reports Server (NTRS)

Federman, S. R.; Menningen, K. L.; Lee, Wei; Stoll, J. B.

1997-01-01

Band oscillator strengths for CO transitions between the electronic states A (l)Pi and X(1)Sigma(+) were measured via absorption with a synchrotron radiation source. When referenced to the well-characterized (5,0) band oscillator strength, our relative values for the (7,0) to (11,0) bands are most consistent with the recent experiments of Chan et al. and the theoretical predictions of Kirby & Cooper. Since the results from various laboratory techniques and theory now agree, analyses of interstellar CO based on absorption from A-X bands are no longer hindered by uncertainties in oscillator strength.

Oscillator strengths of the optical transitions in a semiconductor superlattice under an electric field

NASA Astrophysics Data System (ADS)

Tronc, P.

1992-04-01

The oscillator strengths of the optical transitions in a semiconductor superlattice under an electric field parallel to the growth axis can be calculated using a perturbative model with Bloch envelope functions. The applied electric field and the electron-hole interaction inducing formation of indirect excitons both induce strength asymmetry between the oblique +p and -p transitions of the Wannier-Stark ladder. Features of the photocurrent spectra recorded at low temperature can be accounted for by the present model in a very simple manner. Les forces d'oscillateur des transitions optiques dans un superréseau semiconducteur soumis à un champ électrique parallèle à la direction de croissance, peuvent être calculées à l'aide d'un modèle de perturbation avec des fonctions enveloppes de Bloch. Le champ électrique appliqué ainsi que l'interaction électron-trou, qui induit la formation d'excitons indirects, entraînent une asymétrie entre les forces d'oscillateur des transitions +p et -p dans l'échelle de Wannier-Stark. Certaines caractéristiques des spectres de photocourant enregistrés à basse température peuvent être prévues d'une manière très simple.

Cooperative effect of random and time-periodic coupling strength on synchronization transitions in one-way coupled neural system: mean field approach.

PubMed

Jiancheng, Shi; Min, Luo; Chusheng, Huang

2017-08-01

The cooperative effect of random coupling strength and time-periodic coupling strengh on synchronization transitions in one-way coupled neural system has been investigated by mean field approach. Results show that cooperative coupling strength (CCS) plays an active role for the enhancement of synchronization transitions. There exist an optimal frequency of CCS which makes the system display the best CCS-induced synchronization transitions, a critical frequency of CCS which can not further affect the CCS-induced synchronization transitions, and a critical amplitude of CCS which can not occur the CCS-induced synchronization transitions. Meanwhile, noise intensity plays a negative role for the CCS-induced synchronization transitions. Furthermore, it is found that the novel CCS amplitude-induced synchronization transitions and CCS frequency-induced synchronization transitions are found.

Phase transition at N = 92 in 158Dy

NASA Astrophysics Data System (ADS)

Gupta, J. B.

2016-09-01

Beyond the shape phase transition from the spherical vibrator to the deformed rotor regime at N = 90, the interplay of β- and γ-degrees of freedom becomes important, which affects the relative positions of the Kπ = 0+β- and Kπ = 2+γ-bands. In the microscopic approach of the dynamic pairing plus quadrupole model, a correlation of the strength of the quadrupole force and the formation of the β- and γ-bands in 158Dy is described. The role of the potential energy surface is illustrated. The E2 transition rates in the lower three K-bands and the multi-phonon bands with Kπ = 0+, 2+ and 4+ are well reproduced. The absolute B(E2, 2i+ = 0 2+) (i = 2, 3) serves as a good measure of the quadrupole strength. The role of the single particle Nilsson orbits is also described.

MgH Rydberg series: Transition energies from electron propagator theory and oscillator strengths from the molecular quantum defect orbital method

NASA Astrophysics Data System (ADS)

Corzo, H. H.; Velasco, A. M.; Lavín, C.; Ortiz, J. V.

2018-02-01

Vertical excitation energies belonging to several Rydberg series of MgH have been inferred from 3+ electron-propagator calculations of the electron affinities of MgH+ and are in close agreement with experiment. Many electronically excited states with n > 3 are reported for the first time and new insight is given on the assignment of several Rydberg series. Valence and Rydberg excited states of MgH are distinguished respectively by high and low pole strengths corresponding to Dyson orbitals of electron attachment to the cation. By applying the Molecular Quantum Defect Orbital method, oscillator strengths for electronic transitions involving Rydberg states also have been determined.

X-ray spectroscopy of E2 and M3 transitions in Ni-like W

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

Clementson, J.; Beiersdorfer, P.; Gu, M. F.

2010-01-15

The electric quadrupole (E2) and magnetic octupole (M3) ground-state transitions in Ni-like W{sup 46+} have been measured using high-resolution crystal spectroscopy at the LLNL electron-beam ion trap facility. The lines fall in the soft x-ray region near 7.93 A and were originally observed as an unresolved feature in tokamak plasmas. Using flat ammonium dihydrogen phosphate and quartz crystals, the wavelengths, intensities, and polarizations of the two lines have been measured for various electron-beam energies and compared to intensity and polarization calculations performed using the Flexible Atomic Code (FAC).

X-ray Spectroscopy of E2 and M3 Transitions in Ni-like W

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

Clementson, J; Beiersdorfer, P; Gu, M F

2009-11-09

The electric quadrupole (E2) and magnetic octupole (M3) ground state transitions in Ni-like W{sup 46+} have been measured using high-resolution crystal spectroscopy at the Livermore electron beam ion trap facility. The lines fall in the soft x-ray region near 7.93 {angstrom} and were originally observed as an unresolved feature in tokamak plasmas. Using flat ADP and quartz crystals the wavelengths, intensities, and polarizations of the two lines have been measured for various electron beam energies and compared to intensity and polarization calculations performed using the Flexible Atomic Code (FAC).

Superconductivity in pressurized CeRhG e3 and related noncentrosymmetric compounds

NASA Astrophysics Data System (ADS)

Wang, Honghong; Guo, Jing; Bauer, Eric D.; Sidorov, Vladimir A.; Zhao, Hengcan; Zhang, Jiahao; Zhou, Yazhou; Wang, Zhe; Cai, Shu; Yang, Ke; Li, Aiguo; Li, Xiaodong; Li, Yanchun; Sun, Peijie; Yang, Yi-feng; Wu, Qi; Xiang, Tao; Thompson, J. D.; Sun, Liling

2018-02-01

We report the discovery of superconductivity in pressurized CeRhG e3 , a nonsuperconducting member of the isostructural family of noncentrosymmetric heavy-fermion compounds Ce T X3 (T =Co , Rh, Ir and X =Si , Ge). Superconductivity appears in CeRhG e3 at a pressure of 19.6 GPa and the transition temperature TC reaches a maximum value of 1.3 K at 21.5 GPa. This finding provides an opportunity to establish systematic correlations between superconductivity and material properties within this family. Though ambient-pressure unit-cell volumes and critical pressures for superconductivity vary substantially across the series, all family members reach a maximum TCmax at a common (±1.7%) critical cell volume Vcrit, and TCmax at Vcrit increases with increasing spin-orbit coupling strength of the d electrons. These correlations show that substantial Kondo and spin-orbit couplings favor superconductivity in this family, the latter reflecting the role of broken centrosymmetry.

12 CFR 3.3 - Transitional rules.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 12 Banks and Banking 1 2011-01-01 2011-01-01 false Transitional rules. 3.3 Section 3.3 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY MINIMUM CAPITAL RATIOS; ISSUANCE OF DIRECTIVES Authority and Definitions § 3.3 Transitional rules. Intangible assets, other than mortgage...

12 CFR 3.3 - Transitional rules.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 12 Banks and Banking 1 2012-01-01 2012-01-01 false Transitional rules. 3.3 Section 3.3 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY MINIMUM CAPITAL RATIOS; ISSUANCE OF DIRECTIVES Authority and Definitions § 3.3 Transitional rules. Intangible assets, other than mortgage...

12 CFR 3.3 - Transitional rules.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 12 Banks and Banking 1 2013-01-01 2013-01-01 false Transitional rules. 3.3 Section 3.3 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY MINIMUM CAPITAL RATIOS; ISSUANCE OF DIRECTIVES Authority and Definitions § 3.3 Transitional rules. Intangible assets, other than mortgage...

Results of a Direct Search Using Synchrotron Radiation for the Low-Energy 229Th Nuclear Isomeric Transition

NASA Astrophysics Data System (ADS)

Jeet, Justin; Schneider, Christian; Sullivan, Scott T.; Rellergert, Wade G.; Mirzadeh, Saed; Cassanho, A.; Jenssen, H. P.; Tkalya, Eugene V.; Hudson, Eric R.

2015-06-01

We report the results of a direct search for the 229Th (Iπ=3 /2+←5 /2+ ) nuclear isomeric transition, performed by exposing 229Th -doped LiSrAlF6 crystals to tunable vacuum-ultraviolet synchrotron radiation and observing any resulting fluorescence. We also use existing nuclear physics data to establish a range of possible transition strengths for the isomeric transition. We find no evidence for the thorium nuclear transition between 7.3 eV and 8.8 eV with transition lifetime (1-2) s ≲τ ≲(2000 - 5600 ) s . This measurement excludes roughly half of the favored transition search area and can be used to direct future searches.

Results of a Direct Search Using Synchrotron Radiation for the Low-Energy Th 229 Nuclear Isomeric Transition

DOE PAGES

Jeet, Justin; Schneider, Christian; Sullivan, Scott T.; ...

2015-06-23

We report the results of a direct search for the 229Tn (I π = 3/2 + ← 5/2 +) nuclear isomeric transition, performed by exposing 229Tn-doped LiSrAlF 6 crystals to tunable vacuum-ultraviolet synchrotron radiation and observing any resulting fluorescence. We also use existing nuclear physics data to establish a range of possible transition strengths for the isomeric transition. We find no evidence for the thorium nuclear transition between 7.3 eV and 8.8 eV with transition lifetime (1–2) s≲τ≲ (2000-5600) s. Lastly, this measurement excludes roughly half of the favored transition search area and can be used to direct future searches.

Results of a Direct Search Using Synchrotron Radiation for the Low-Energy (229)Th Nuclear Isomeric Transition.

PubMed

Jeet, Justin; Schneider, Christian; Sullivan, Scott T; Rellergert, Wade G; Mirzadeh, Saed; Cassanho, A; Jenssen, H P; Tkalya, Eugene V; Hudson, Eric R

2015-06-26

We report the results of a direct search for the (229)Th (I(π)=3/2(+)←5/2(+)) nuclear isomeric transition, performed by exposing (229)Th-doped LiSrAlF(6) crystals to tunable vacuum-ultraviolet synchrotron radiation and observing any resulting fluorescence. We also use existing nuclear physics data to establish a range of possible transition strengths for the isomeric transition. We find no evidence for the thorium nuclear transition between 7.3 eV and 8.8 eV with transition lifetime (1-2) s≲τ≲(2000-5600)  s. This measurement excludes roughly half of the favored transition search area and can be used to direct future searches.

206Pb+n resonances for E=600-900 keV: Neutron strength functions

NASA Astrophysics Data System (ADS)

Horen, D. J.; Harvey, J. A.; Hill, N. W.

1981-11-01

Data from high resolution neutron transmission and differential scattering measurements performed on 206Pb have been analyzed for E=600-900 keV. Resonance parameters (i.e., E, l, J, and Γn) have been deduced for many of the 161 resonances observed. Strength functions and potential phase shifts for s-, p-, and d-wave neutrons for En-0-900 keV are compared with optical model calculations. It is found that the phase contributed by the external R function as well as the integrated neutron strength functions can be reproduced for the s and d waves with a well depth of V0=50.4 MeV for the real potential and WD=6.0 MeV for an imaginary surface potential. Somewhat smaller values (V0=48.7 MeV and WD=2.0 MeV) are required to reproduce the p-wave data. These values of the real potential are also found to give the experimentally observed binding energies for the 4s12, 3d32, and 3d52 single particle levels (V0=50.4 MeV), and the 3p12 single particle level (V0=48.7 MeV). Nuclear level densities for s and d waves are found to be well represented by a constant temperature model. However, the model under estimates the number of p-wave resonances. NUCLEAR REACTIONS 206Pb(n), (n,n), E=600-900 keV; measured σT(E), σ(E,θ). 207Pb deduced resonance parameters, Jπ, Γn, neutron strength functions, optical model parameters for l=0,1,2.

Stark Interference of Electric and Magnetic Dipole Transitions in the A-X Band of OH.

PubMed

Schewe, H Christian; Zhang, Dongdong; Meijer, Gerard; Field, Robert W; Sartakov, Boris G; Groenenboom, Gerrit C; van der Avoird, Ad; Vanhaecke, Nicolas

2016-04-15

An experimental method is demonstrated that allows determination of the ratio between the electric (E1) and magnetic (M1) transition dipole moments in the A-X band of OH, including their relative sign. Although the transition strengths differ by more than 3 orders of magnitude, the measured M1-to-E1 ratio agrees with the ratio of the ab initio calculated values to within 3%. The relative sign is found to be negative, also in agreement with theory.

Optical oscillator strength distribution of amino acids from 3 to 250 eV and examination of the Thomas Reiche Kuhn sum rule

NASA Astrophysics Data System (ADS)

Kamohara, Masumi; Izumi, Yudai; Tanaka, Masafumi; Okamoto, Keiko; Tanaka, Masahito; Kaneko, Fusae; Kodama, Yoko; Koketsu, Toshiyuki; Nakagawa, Kazumichi

2008-10-01

Absorption spectra of thin films of glycine (Gly), alanine (Ala), valine (Val), serine (Ser), leucine (Leu), phenylalanine (Phe) and methinine (Met) were measured in absolute values of absorption cross section σ( E) for the photon energy E from 3 to 250 eV. We translated σ( E) into the optical oscillator strength distribution df/dE and we examined the Thomas-Reiche-Kuhn sum rule [Hirschfelder, J.O., Curtiss, C.F., Bird, R.B., 1954. Molecular Theory of Gases and Liquids. Wiley, New York, p. 890]. We concluded that T-R-K sum rule was correctly applicable for such relatively large size of biomolecules.

Photon transitions in Upsilon(2S) and Upsilon(3S) decays.

PubMed

Artuso, M; Boulahouache, C; Blusk, S; Butt, J; Dambasuren, E; Dorjkhaidav, O; Li, J; Menaa, N; Mountain, R; Muramatsu, H; Nandakumar, R; Redjimi, R; Sia, R; Skwarnicki, T; Stone, S; Wang, J C; Zhang, K; Csorna, S E; Bonvicini, G; Cinabro, D; Dubrovin, M; Bornheim, A; Pappas, S P; Weinstein, A J; Rosner, J L; Briere, R A; Chen, G P; Ferguson, T; Tatishvili, G; Vogel, H; Watkins, M E; Adam, N E; Alexander, J P; Berkelman, K; Cassel, D G; Crede, V; Duboscq, J E; Ecklund, K M; Ehrlich, R; Fields, L; Galik, R S; Gibbons, L; Gittelman, B; Gray, R; Gray, S W; Hartill, D L; Heltsley, B K; Hertz, D; Hsu, L; Jones, C D; Kandaswamy, J; Kreinick, D L; Kuznetsov, V E; Mahlke-Krüger, H; Meyer, T O; Onyisi, P U E; Patterson, J R; Peterson, D; Pivarski, J; Riley, D; Ryd, A; Sadoff, A J; Schwarthoff, H; Shepherd, M R; Stroiney, S; Sun, W M; Thayer, J G; Urner, D; Wilksen, T; Weinberger, M; Athar, S B; Avery, P; Breva-Newell, L; Patel, R; Potlia, V; Stoeck, H; Yelton, J; Rubin, P; Cawlfield, C; Eisenstein, B I; Gollin, G D; Karliner, I; Kim, D; Lowrey, N; Naik, P; Sedlack, C; Selen, M; Thaler, J J; Williams, J; Wiss, J; Edwards, K W; Besson, D; Pedlar, T K; Cronin-Hennessy, D; Gao, K Y; Gong, D T; Kubota, Y; Lang, B W; Li, S Z; Poling, R; Scott, A W; Smith, A; Stepaniak, C J; Dobbs, S; Metreveli, Z; Seth, K K; Tomaradze, A; Zweber, P; Ernst, J; Mahmood, A H; Arms, K; Gan, K K; Severini, H; Asner, D M; Dytman, S A; Love, W; Mehrabyan, S; Mueller, J A; Savinov, V; Li, Z; Lopez, A; Mendez, H; Ramirez, J; Huang, G S; Miller, D H; Pavlunin, V; Sanghi, B; Shibata, E I; Shipsey, I P J; Adams, G S; Chasse, M; Cravey, M; Cummings, J P; Danko, I; Napolitano, J; Park, C S; Park, W; Thayer, J B; Thorndike, E H; Coan, T E; Gao, Y S; Liu, F; Stroynowski, R

2005-01-28

We have studied the inclusive photon spectra in Upsilon(2S) and Upsilon(3S) decays using a large statistics data sample obtained with the CLEO III detector. We present the most precise measurements of electric dipole (E1) photon transition rates and photon energies for Upsilon(2S) --> gammachi(bJ)(1P) and Upsilon(3S) --> gammachi(bJ)(2P) (J = 0, 1, 2). We measure the rate for a rare E1 transition Upsilon(3S) --> gammachi(b0)(1P) for the first time. We also set upper limits on the rates for the hindered magnetic dipole (M1) transitions to the eta(b)(1S) and eta(b)(2S) states.

E1 and M1 γ-strength functions in 144Nd

DOE PAGES

Voinov, A. V.; Grimes, S. M.

2015-12-14

Both E1 and M1 γ-strength functions below the neutron separation energy were analyzed based on experimental data from 143Nd(n,γ) 144Nd and 143Nd(n,γα) 140Ce reactions. It is confirmed that the commonly adopted E1 model based on the temperature dependence of the width of the giant dipole resonance works well. The popular M1 strength function due to the spin-flip magnetic resonance located near the neutron binding energy is not capable of reproducing experimental data. As a result, the low-energy enhancement of the M1 strength or the energy-independent model of Weisskopf, both leading to the low-energy strength sizable to E1 one, fit experimentalmore » data best.« less

Rates of E1, E2, M1, and M2 transitions in Ni II

NASA Astrophysics Data System (ADS)

Cassidy, C. M.; Hibbert, A.; Ramsbottom, C. A.

2016-03-01

Aims: We present rates for all E1, E2, M1, and M2 transitions among the 295 fine-structure levels of the configurations 3d9, 3d84s, 3d74s2, 3d84p, and 3d74s4p, determined through an extensive configuration interaction calculation. Methods: The CIV3 code developed by Hibbert and coworkers is used to determine for these levels configuration interaction wave functions with relativistic effects introduced through the Breit-Pauli approximation. Results: Two different sets of calculations have been undertaken with different 3d and 4d functions to ascertain the effect of such variation. The main body of the text includes a representative selection of data, chosen so that key points can be discussed. Some analysis to assess the accuracy of the present data has been undertaken, including comparison with earlier calculations and the more limited range of experimental determinations. The full set of transition data is given in the supplementary material as it is very extensive. Conclusions: We believe that the present transition data are the best currently available. Full Table 4 and Tables 5-8 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/587/A107

Picosecond excite-and-probe absorption measurement of the intra-2E(g)E(3/2)-state vibrational relaxation time in Ti(3+):Al2O3

NASA Technical Reports Server (NTRS)

Gayen, S. K.; Wang, W. B.; Petricevic, V.; Yoo, K. M.; Alfano, R. R.

1987-01-01

The Ti(3+)-doped Al2O3 has been recently demonstrated to be a tunable solid-state laser system with Ti(3+) as the laser-active ion. In this paper, the kinetics of vibrational transitions in the 2E(g)E(3/2) electronic state of Ti(3+):Al2O3a (crucial for characterizing new host materials for the Ti ion) was investigated. A 527-nm 5-ps pulse was used to excite a band of higher vibrational levels of the 2E(g)E(3/2) state, and the subsequent growth of population in the zero vibrational level and lower vibrational levels was monitored by a 3.9-micron picosecond probe pulse. The time evolution curve in the excited 2E(g)E(3/2) state at room temperature was found to be characterized by a sharp rise followed by a long decay, the long lifetime decay reflecting the depopulation of the zero and the lower vibrational levels of the 2E(g)E(3/2) state via radiative transitions. An upper limit of 3.5 ps was estimated for intra-2E(g)E(3/2)-state vibrational relaxation time.

Influence of droplet size, pH and ionic strength on endotoxin-triggered ordering transitions in liquid crystalline droplets

PubMed Central

Miller, Daniel S.; Abbott, Nicholas L.

2012-01-01

We report an investigation of ordering transitions that are induced in water-dispersed, micrometer-sized droplets of a thermotropic liquid crystal (LC) by the bacterial lipopolysaccharide endotoxin. We reveal that the ordering transitions induced by endotoxin – from a bipolar state of the droplets to a radial state – are strongly dependent on the size of the LC droplets. Specifically, as the diameters of the LC droplets increase from 2 μm to above 10 μm (in phosphate buffered saline with an ionic strength of 90 mM and a pH of 7.2), we measured the percentage of droplets exhibiting a radial configuration in the presence of 100 pg/mL endotoxin to decrease from 98 ± 1 % to 3 ± 2 %. In addition, we measured a decrease in either the ionic strength or pH of the aqueous phase to reduce the percentage of droplets exhibiting a radial configuration in the presence of endotoxin. These results, when interpreted within the context of a simple thermodynamic model that incorporates the contributions of elasticity and surface anchoring to the free energies of the LC droplets, lead us to conclude that (i) the elastic constant K24 plays a central role in determining the size-dependent response of the LC droplets to endotoxin, and (ii) endotoxin-triggered ordering transitions occur only under solution conditions (pH, ionic strength) where the combined contributions of elasticity and surface anchoring to the free energies of the bipolar and radial configurations of the LC droplets are similar in magnitude. Our analysis also suggests that the presence of endotoxin perturbs the free energies of the LC droplets by ~10−17 J/droplet, which is comparable to the standard free energy of self-association of ~103 endotoxin molecules. These results, when combined with prior reports of localization of endotoxin at the center of LC droplets, are consistent with the hypothesis that self-assembly of endotoxin within micrometer-sized LC droplets provides the driving force for the ordering

Relativistic distorted-wave collision strengths for the 49 Δn=0 optically allowed transitions with n=2 in the 67 N-like ions with 26≤Z≤92

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

Fontes, Christopher J., E-mail: cjf@lanl.gov; Zhang, Hong Lin

2014-09-15

Relativistic distorted-wave collision strengths have been calculated for the 49 Δn=0 optically allowed transitions with n=2 in the 67 N-like ions with nuclear charge number Z in the range 26≤Z≤92. The calculations were made for the four final, or scattered, electron energies E{sup ′}=0.20, 0.42, 0.80, and 1.40, where E{sup ′} is in units of Z{sub eff}{sup 2} Ry with Z{sub eff}=Z−5. In the present calculations, an improved “top-up” method, which employs relativistic plane waves, was used to obtain the high partial-wave contribution for each transition, in contrast to the partial-relativistic Coulomb–Bethe approximation used in the previous work by Zhangmore » and Sampson [H.L. Zhang and D.H. Sampson, At. Data Nucl. Data Tables 72 (1999) 153]. In that earlier work, collision strengths were also provided for N-like ions, but for a more comprehensive data set consisting of all possible 105 Δn=0 transitions, six scattered energies and the 81 ions with Z in the range 12≤Z≤92. The collision strengths covered in the present work should be more accurate than the corresponding data given by Zhang and Sampson [H.L. Zhang and D.H. Sampson, At. Data Nucl. Data Tables 72 (1999) 153] and are presented here to replace those earlier results.« less

Relativistic distorted-wave collision strengths for the 16 Δn=0 optically allowed transitions with n=2 in the 67 O-like ions with 26≤Z≤92

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

Fontes, Christopher J., E-mail: cjf@lanl.gov; Zhang, Hong Lin

2015-01-15

Relativistic distorted-wave collision strengths have been calculated for the 16 Δn=0 optically allowed transitions with n=2 in the 67 O-like ions with nuclear charge number Z in the range 26≤Z≤92. The calculations were made for the four final, or scattered, electron energies E{sup ′}=0.20,0.42,0.80, and 1.40, where E{sup ′} is in units of Z{sub eff}{sup 2} Ry with Z{sub eff}=Z−5.83. In the present calculations, an improved “top-up” method, which employs relativistic plane waves, was used to obtain the high partial-wave contribution for each transition, in contrast to the partial-relativistic Coulomb–Bethe approximation used in previous work by Zhang and Sampson [H.L.more » Zhang, D.H. Sampson, At. Data Nucl. Data Tables 82 (2002) 357]. In that earlier work, collision strengths were also provided for O-like ions, but for a more comprehensive data set consisting of all possible 45 Δn=0 transitions, six scattered energies, and the 79 ions with Z in the range 14≤Z≤92. The collision strengths covered in the present work should be more accurate than the corresponding data given by Zhang and Sampson [H.L. Zhang, D.H. Sampson, At. Data Nucl. Data Tables 82 (2002) 357] and are presented here to replace those earlier results.« less

Na(+) transport, and the E(1)P-E(2)P conformational transition of the Na(+)/K(+)-ATPase.

PubMed Central

Babes, A; Fendler, K

2000-01-01

We have used admittance analysis together with the black lipid membrane technique to analyze electrogenic reactions within the Na(+) branch of the reaction cycle of the Na(+)/K(+)-ATPase. ATP release by flash photolysis of caged ATP induced changes in the admittance of the compound membrane system that are associated with partial reactions of the Na(+)/K(+)-ATPase. Frequency spectra and the Na(+) dependence of the capacitive signal are consistent with an electrogenic or electroneutral E(1)P <--> E(2)P conformational transition which is rate limiting for a faster electrogenic Na(+) dissociation reaction. We determine the relaxation rate of the rate-limiting reaction and the equilibrium constants for both reactions at pH 6.2-8.5. The relaxation rate has a maximum value at pH 7.4 (approximately 320 s(-1)), which drops to acidic (approximately 190 s(-1)) and basic (approximately 110 s(-1)) pH. The E(1)P <--> E(2)P equilibrium is approximately at a midpoint position at pH 6.2 (equilibrium constant approximately 0.8) but moves more to the E(1)P side at basic pH 8.5 (equilibrium constant approximately 0.4). The Na(+) affinity at the extracellular binding site decreases from approximately 900 mM at pH 6.2 to approximately 200 mM at pH 8.5. The results suggest that during Na(+) transport the free energy supplied by the hydrolysis of ATP is mainly used for the generation of a low-affinity extracellular Na(+) discharge site. Ionic strength and lyotropic anions both decrease the relaxation rate. However, while ionic strength does not change the position of the conformational equilibrium E(1)P <--> E(2)P, lyotropic anions shift it to E(1)P. PMID:11053130

Wetting Transitions in ^4He/^3He Mixtures on Cesium

NASA Astrophysics Data System (ADS)

Ross, David

1997-03-01

Over the last several years, helium on cesium has proven to be an ideal model system for the study of wetting and wetting transitions(E. Cheng, M.W. Cole, W.F. Saam, and J. Treiner, Phys. Rev. Lett. 67), 1007 (1991).^,(J.E. Rutledge and P. Taborek, Phys. Rev. Lett. 69), 937 (1992).^,(D. Ross, J.E. Rutledge, and P. Taborek, Phys. Rev. Lett. 76), 2350 (1996).. This presentation will focus on the adsorption of binary liquid mixtures of the helium isotopes, ^3He and ^4He, on cesium substrates over a range of temperatures extending from 0.2 K to 1.0 K. The results, spanning ^3He concentrations from 0 to 1, constitute the first experimentally constructed complete wetting phase diagram for a two component liquid at a weakly binding substrate. The wetting behavior is particularly interesting in the vicinity of bulk liquid phase separation. A wetting transition of the ^4He rich liquid between the ^3He rich liquid and the cesium substrate has been found with Tw = 0.53 K. The surface phase transition line associated with this wetting transition is found to extend to both sides of the bulk phase separation line. On the ^3He rich side it is a prewetting line, and on the ^4He rich side it becomes a line of triple point induced dewetting transitions. General arguments indicate that this behavior should be typical of a large class of binary liquid mixtures at weakly binding substrates.

Theoretical transition probabilities, oscillator strengths, and radiative lifetimes of levels in Pb IV

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

Alonso-Medina, A.; Colon, C., E-mail: cristobal.colon@upm.e; Porcher, P.

2011-01-15

Transition probabilities and oscillator strengths of 176 spectral lines with astrophysical interest arising from 5d{sup 10}ns (n = 7,8), 5d{sup 10}np (n = 6,7), 5d{sup 10}nd (n = 6,7), 5d{sup 10}5f, 5d{sup 10}5g, 5d{sup 10}nh (n = 6,7,8), 5d{sup 9}6s{sup 2}, and 5d{sup 9}6s6p configurations, and radiative lifetimes for 43 levels of Pb IV, have been calculated. These values were obtained in intermediate coupling (IC) and using relativistic Hartree-Fock calculations including core-polarization effects. For the IC calculations, we use the standard method of least-square fitting from experimental energy levels by means of the Cowan computer code. The inclusion in thesemore » calculations of the 5d{sup 10}7p and 5d{sup 10}5f configurations has facilitated a complete assignment of the energy levels in the Pb IV. Transition probabilities, oscillator strengths, and radiative lifetimes obtained are generally in good agreement with the experimental data.« less

Microstructural evolution and mechanical characterization for the A508-3 steel before and after phase transition

NASA Astrophysics Data System (ADS)

Lu, Chuanyang; He, Yanming; Gao, Zengliang; Yang, Jianguo; Jin, Weiya; Xie, Zhigang

2017-11-01

Nuclear power, as a reliable clean and economical energy source, has gained great attention from all over the world. The A508-3 steel will be introduced as the structural materials for Chinese nuclear reactor pressure vessels (RPVs). This work investigated the temperature-dependence microstructural evolution during high-temperature heat treatments, and built the relationship between the microstructure and mechanical properties for the steel before and after phase transition. The results show that the original steel consists of the bainite, allotriomorphic ferrite, retained austenite and few Mo-rich M2C carbides. The phase-transition temperature of the steel is determined to be 750 °C. The tensile tests performed at 20-1000 °C indicate that both of the yield strength and ultimate tensile strength decrease monotonously with increasing the temperature. Before phase transition, precipitation of cementite from the retained austenite and coarsening of cementite at the austenite-ferrite interphases should be responsible for their sharp decrease. After phase transition, the growth of austenite grain reduces the strength moderately. As for the elongation, however, it increases dramatically when the testing temperature is over 750 °C, due to the dissolution of cementite and formation of austenite. The obtained results will provide some fundamental data to understand and implement the In-Vessel Retention strategy.

Improving the toughness of ultrahigh strength steel

NASA Astrophysics Data System (ADS)

Sato, Koji

2002-01-01

The ideal structural steel combines high strength with high fracture toughness. This dissertation discusses the toughening mechanism of the Fe/Co/Ni/Cr/Mo/C steel, AerMet 100, which has the highest toughness/strength combination among all commercial ultrahigh strength steels. The possibility of improving the toughness of this steel was examined by considering several relevant factors. Chapter 1 reviews the mechanical properties of ultrahigh strength steels and the physical metallurgy of AerMet 100. It also describes the fracture mechanisms of steel, i.e. ductile microvoid coalescence, brittle transgranular cleavage, and intergranular separation. Chapter 2 examines the strength-toughness relationship for three heats of AerMet 100. A wide variation of toughness is obtained at the same strength level. The toughness varies despite the fact that all heat fracture in the ductile fracture mode. The difference originates from the inclusion content. Lower inclusion volume fraction and larger inclusion spacing gives rise to a greater void growth factor and subsequently a higher fracture toughness. The fracture toughness value, JIc, is proportional to the particle spacing of the large non-metallic inclusions. Chapter 3 examines the ductile-brittle transition of AerMet 100 and the effect of a higher austenitization temperature, using the Charpy V-notch test. The standard heat treatment condition of AerMet 100 shows a gradual ductile-brittle transition due to its fine effective grain size. Austenitization at higher temperature increases the prior austenite grain size and packet size, leading to a steeper transition at a higher temperature. Both transgranular cleavage and intergranular separation are observed in the brittle fracture mode. Chapter 4 examines the effect of inclusion content, prior austenite grain size, and the amount of austenite on the strength-toughness relationship. The highest toughness is achieved by low inclusion content, small prior austenite grain size

MASH TL-3 testing and evaluation of the TXDOT T131RC bridge rail transition.

DOT National Transportation Integrated Search

2013-03-01

This project designed and crash tested a transition design for the Texas Department of Transportation (TxDOT) T131RC Bridge Rail that would meet the strength and safety performance criteria for Test Level 3 of American Association of State Highway Of...

STM studies of topological phase transition in (Bi,In)2Se3

NASA Astrophysics Data System (ADS)

Zhang, Wenhan; Wang, Xueyun; Cheong, Sang-Wook; Wu, Weida; Weida Wu Team; Sang-Wook Cheong Collaboration

Topological insulators (TI) are a class of materials with insulating bulk and metallic surface state, which is the result of band inversion induced by strong spin-orbit coupling (SOC). The transition from topological phase to non-topological phase is of great significance. In theory, topological phase transition is realized by tuning SOC strength. It is characterized by the process of gap closing and reopening. Experimentally it was observed in two systems: TlBi(S1-xSex)2 and (Bi1-xInx)2 Se3 where the transition is realized by varying isovalent elements doping concentration. However, none of the previous studies addressed the impact of disorder, which is inevitable in doped systems. Here, we present a systematic scanning tunneling microscopy/spectroscopy study on (Bi1-xInx)2 Se3 single crystals with different In concentrations across the transition. Our results reveal an electronic inhomogeneity due to the random distribution of In defects which locally suppress the topological surface states. Our study provides a new angle of understanding the topological transition in the presence of strong disorders. This work is supported by NSF DMR-1506618.

Partial glass isosymmetry transition in multiferroic hexagonal ErMn O 3

DOE PAGES

Barbour, A.; Alatas, A.; Liu, Y.; ...

2016-02-08

Ferroelectric transitions of a hexagonal multiferroic, ErMnO 3, are studied by x-ray scattering techniques. An isosymmetry transition, similar to that previously observed for YMnO 3, approximately 300 K below the well-known ferroic transition temperature is investigated. The partial glassy behavior of the isosymmetry transition is identified by appearance of quasi-elastic scattering lines in high-energy-resolution scans. The glassy behavior is further supported by the increased interlayer decorrelation of (√3×√3)R30º ordering below the isosymmetry transition. The transition behavior is considered for possible hidden sluggish modes and two-step phase transitions theoretically predicted for the stacked triangular antiferromagnets. The in-plane azimuthal (orientational) ordering behaviorsmore » were also compared to the theoretical predictions. Coherent x-ray speckle measurements show unambiguously that the domain sizes decrease anomalously near both the isosymmetry and ferroic transitions. However, domain boundary fluctuations increase monotonically with an Arrhenius form with an activation energy of 0.54(5) eV through both transitions.« less

Energy levels and radiative rates for transitions in B-like to F-like Kr ions (Kr XXXII XXVIII)

NASA Astrophysics Data System (ADS)

Aggarwal, K. M.; Keenan, F. P.; Lawson, K. D.

2008-05-01

Energy levels, radiative rates, oscillator strengths, line strengths, and lifetimes have been calculated for transitions in B-like to F-like Kr ions, Kr XXXIII-XXVIII. For the calculations, the fully relativistic GRASP code has been adopted, and results are reported for all electric dipole (E1), electric quadrupole (E2), magnetic dipole (M1), and magnetic quadrupole (M2) transitions among the lowest 125, 236, 272, 226, and 113 levels of Kr XXXII, Kr XXXI, Kr XXX, Kr XXIX, and Kr XXVIII, respectively, belonging to the n ⩽ 3 configurations. Comparisons are made with earlier available theoretical and experimental results, and some discrepancies have been noted and explained.

Laboratory astrophysics under the ultraviolet, visible, and gravitational astrophysics research program: Oscillator strengths for ultraviolet atomic transitions

NASA Technical Reports Server (NTRS)

Federman, Steven R.

1992-01-01

The conditions within astrophysical environments can be derived from observational data on atomic and molecular lines. For instance, the density and temperature of the gas are obtained from relative populations among energy levels. Information on populations comes about only when the correspondence between line strength and abundance is well determined. The conversion from line strength to abundance involves knowledge of meanlives and oscillator strengths. For many ultraviolet atomic transitions, unfortunately, the necessary data are either relatively imprecise or not available. Because of the need for more and better atomic oscillator strengths, our program was initiated. Through beam-foil spectroscopy, meanlives of ultraviolet atomic transitions are studied. In this technique, a nearly isotopically pure ion beam of the desired element is accelerated. The beam passes through a thin carbon foil (2 mg/cu cm), where neutralization, ionization, and excitation take place. The dominant process depends on the energy of the beam. Upon exiting the foil, the decay of excited states is monitored via single-photon-counting techniques. The resulting decay curve yields a meanlife. The oscillator strength is easily obtained from the meanlife when no other decay channels are presented. When other channels are present, additional measurements or theoretical calculations are performed in order to extract an oscillator strength. During the past year, three atomic systems have been studied experimentally and/or theoretically; they are Ar, I, Cl I, and N II. The results for the first two are important for studies of interstellar space, while the work on N II bears on processes occurring in planetary atmospheres.

Enhancement of yield strength in zirconium metal through high-pressure induced structural phase transition

NASA Astrophysics Data System (ADS)

Zhao, Yusheng; Zhang, Jianzhong

2007-11-01

We report here a high-pressure phase-transition induced strengthening in ultrapure zirconium metal. The determined yield strength shows more than sixfold abrupt increase at the transition pressure of Pc=6GPa, from σyα≈180MPa in the low-pressure phase of α-Zr to σyω≈1180MPa in the high-pressure phase of ω-Zr. The observed enhancement provides an alternate route for material strengthening and is the most significant among the known strengthening techniques for metals. Our findings support the theoretical simulations of the substantial covalent bonding and "rougher" corrugation of slip planes for dislocations in the ω-phase of zirconium.

E1 transitions from octupole vibration states

NASA Astrophysics Data System (ADS)

Cottle, P. D.

1993-04-01

Electric dipole moments are extracted from data for E1 transitions deexciting octupole vibration states in nineteen nuclei. The moments are then compared to values calculated using the droplet model prescription of Dorso, Myers, and Swiatecki. It is found that the E1 moments in quadrupole deformed nuclei can be reproduced with the droplet model using the same model parameters that reproduce atomic masses and fission barriers. This result supports the suggestion of Butler and Nazarewicz that single particle effects are usually much smaller than macroscopic effects in E1 transitions associated with octupole vibrations in reflection symmetric deformed nuclei.

Effect of Omega-3 and Vitamins E + C Supplements on the Concentration of Serum B-Vitamins and Plasma Redox Aminothiol Antioxidant Status in Elderly Men after Strength Training for Three Months.

PubMed

Stea, Tonje Holte; Stølevik, Solvor B; Berntsen, Sveinung; Ezzathkah Bastani, Nasser; Paulsen, Gøran; Lohne Seiler, Hilde; Hetlelid, Ken J; Blomhoff, Rune; Mansoor, Mohammad Azam

2016-01-01

Data on redox plasma aminothiol status in individuals on strength training are very limited. Therefore, we studied the effect of omega-3 and vitamins E + C supplementation on the concentration of B-vitamins and redox aminothiol status in elderly men after strength training for 3 months. Healthy men, age 60 ± 6 (mean ± SD) were randomly divided into 3 groups: group I received placebo (n = 17), group II consumed omega-3 (700 mg, n = 17), and group III consumed vitamins E + C (235 mg +1 g, n = 16) daily for 3 months. All participants completed a strength training program for the same period. The concentration of serum vitamin B12 decreased and the concentration of serum folate increased in group I after the intervention (p = 0.01, p = 0.009). The concentration of plasma 5-pyridoxal phosphate decreased in groups II and III (p = 0.03 and p = 0.01), whereas the concentration of serum uric acid decreased only in group II (p = 0.02). We detected an increase in the concentration of reduced form of aminothiols in all groups (p < 0.001). The red/ox plasma aminothiol status was significantly changed in all groups after the intervention (p < 0.05). Omega-3 and vitamins E + C supplementation affect the concentrations of serum B-vitamins and redox plasma aminothiol status in healthy elderly men on strength training. © 2016 S. Karger AG, Basel.

The E(2) symmetry and quantum phase transition in the two-dimensional limit of the vibron model

NASA Astrophysics Data System (ADS)

Zhang, Yu; Pan, Feng; Liu, Yu-Xin; Draayer, J. P.

2010-11-01

We study in detail the relation between the two-dimensional Euclidean dynamical E(2) symmetry and the quantum phase transition in the two-dimensional limit of the vibron model, called the U(3) vibron model. Both geometric and algebraic descriptions of the U(3) vibron model show that structures of low-lying states at the critical point of the model with a quartic potential as its classical limit can be approximately described by the E(2) symmetry. We also fit the finite-size scaling exponent of the energy levels and E1 transition rates in the F(2) model, which is exactly the E(2) model but with truncation in its Hilbert subspace, as well as those at the critical point in the U(3) vibron model. The N-scaling power law around the critical point shows that the E(2) symmetry is well preserved even for cases with finite number of bosons. In addition, two kinds of experimentally accessible effective order parameters, such as the energy ratios E_{2_1}/E_{1_1}, E_{3_1}/E_{1_1} and E1 transition ratios \\frac{B(E1;2_1\\rightarrow 1_1)}{B(E1;1_1\\rightarrow 0_1)}, \\frac{B(E1;0_2\\rightarrow 1_1)}{B(E1;1_1\\rightarrow 0_1)}, are proposed to identify the second-order phase transition in such systems. Possible empirical examples exhibiting approximate E(2) symmetry are also presented.

Pressure-induced phase transitions in the CdC r2S e4 spinel

NASA Astrophysics Data System (ADS)

Efthimiopoulos, I.; Liu, Z. T. Y.; Kucway, M.; Khare, S. V.; Sarin, P.; Tsurkan, V.; Loidl, A.; Wang, Y.

2016-11-01

We have conducted high-pressure x-ray diffraction and Raman spectroscopic studies on the CdC r2S e4 spinel at room temperature up to 42 GPa. We have resolved three structural transitions up to 42 GPa, i.e., the starting F d 3 ¯m phase transforms at ˜11 GPa into a tetragonal I 41/a m d structure, an orthorhombic distortion was observed at ˜15 GPa , whereas structural disorder initiates beyond 25 GPa. Our ab initio density functional theory studies successfully reproduced the observed crystalline-to-crystalline structural transitions. In addition, our calculations propose an antiferromagnetic ordering as a potential magnetic ground state for the high-pressure tetragonal and orthorhombic modifications, compared with the starting ferromagnetic phase. Furthermore, the computational results indicate that all phases remain insulating in their stability pressure range, with a direct-to-indirect band gap transition for the F d 3 ¯m phase taking place at 5 GPa. We attempted also to offer an explanation behind the peculiar first-order character of the F d 3 ¯m (cubic ) →I 41/a m d (tetragonal) transition observed for several relevant Cr spinels, i.e., the sizeable volume change at the transition point, which is not expected from space group symmetry considerations. We detected a clear correlation between the cubic-tetragonal transition pressures and the next-nearest-neighbor magnetic exchange interactions for the Cr-bearing sulfide and selenide members, a strong indication that the cubic-tetragonal transitions in these systems are principally governed by magnetic effects.

Transition sum rules in the shell model

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

Lu, Yi; Johnson, Calvin W.

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, in the case of the EWSR a double commutator. While most prior applications of the double-commutator have been to special cases, we derive general formulas for matrix elements of bothmore » 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 then 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 (E1) sum rule against the famous Thomas-Reiche-Kuhn version. We also find surprising systematic behaviors for ground state electric quadrupole (E2) centroids in the $sd$-shell.« less

Transition sum rules in the shell model

DOE PAGES

Lu, Yi; Johnson, Calvin W.

2018-03-29

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, in the case of the EWSR a double commutator. While most prior applications of the double-commutator have been to special cases, we derive general formulas for matrix elements of bothmore » 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 then 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 (E1) sum rule against the famous Thomas-Reiche-Kuhn version. We also find surprising systematic behaviors for ground state electric quadrupole (E2) centroids in the $sd$-shell.« less

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.

Experimental tobacco marketplace: substitutability of e-cigarette liquid for cigarettes as a function of nicotine strength.

PubMed

Pope, Derek A; Poe, Lindsey; Stein, Jeffrey S; Kaplan, Brent A; Heckman, Bryan W; Epstein, Leonard H; Bickel, Warren K

2018-04-18

The experimental tobacco marketplace (ETM) provides a method to estimate, prior to implementation, the effects of new products or policies on purchasing across various products in a complex tobacco marketplace. We used the ETM to examine the relationship between nicotine strength and substitutability of alternative products for cigarettes to contribute to the literature on regulation of e-liquid nicotine strength. The present study contained four sampling and four ETM purchasing sessions. During sampling sessions, participants were provided 1 of 4 e-liquid strengths (randomised) to sample for 2 days followed by an ETM purchasing session. The nicotine strength sampled in the 2 days prior to an ETM session was the same strength available for purchase in the next ETM. Each participant sampled and could purchase 0 mg/mL, 6 mg/mL, 12 mg/mL and 24 mg/mL e-liquid, among other products, during the study. Cigarette demand was unaltered across e-liquid strength. E-liquid was the only product to substitute for cigarettes across more than one e-liquid strength. Substitutability increased as a function of e-liquid strength, with the 24 mg/mL displaying the greatest substitutability of all products. The present study found that e-liquid substitutability increased with nicotine strength, at least up to 24 mg/mL e-liquid. However, the effects of e-liquid nicotine strength on cigarette purchasing were marginal and total nicotine purchased increased as e-liquid nicotine strength increased. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Electron impact excitation of the electronic states of N2. III - Transitions in the 12.5-14.2-eV energy-loss region at incident energies of 40 and 60 eV

NASA Technical Reports Server (NTRS)

Chutjian, A.; Trajmar, S.; Cartwright, D. C.

1977-01-01

Analysis of electron energy-loss data at incident electron energies of 40 and 60 eV has led to the determination of normalized absolute differential cross sections for electron-impact excitation of five optically-allowed singlet states, two known triplet states, and two unknown triplet-like states of N2, lying in the energy-loss range 12.5-14.2 eV. The range of scattering angles was 5 to 138 deg. The optically allowed transitions and the known triplet excitations are identified. Cross sections for excitation to two unidentified triplet-like states at 13.155 and 13.395 eV were also obtained. The relationship of the generalized oscillator strength for the dipole-allowed states obtained from the described data to known optical oscillator strengths is discussed.

All-atom simulations and free-energy calculations of coiled-coil peptides with lipid bilayers: binding strength, structural transition, and effect on lipid dynamics

NASA Astrophysics Data System (ADS)

Woo, Sun Young; Lee, Hwankyu

2016-03-01

Peptides E and K, which are synthetic coiled-coil peptides for membrane fusion, were simulated with lipid bilayers composed of lipids and cholesterols at different ratios using all-atom models. We first calculated free energies of binding from umbrella sampling simulations, showing that both E and K peptides tend to adsorb onto the bilayer surface, which occurs more strongly in the bilayer composed of smaller lipid headgroups. Then, unrestrained simulations show that K peptides more deeply insert into the bilayer with partially retaining the helical structure, while E peptides less insert and predominantly become random coils, indicating the structural transition from helices to random coils, in quantitative agreement with experiments. This is because K peptides electrostatically interact with lipid phosphates, as well as because hydrocarbons of lysines of K peptide are longer than those of glutamic acids of E peptide and thus form stronger hydrophobic interactions with lipid tails. This deeper insertion of K peptide increases the bilayer dynamics and a vacancy below the peptide, leading to the rearrangement of smaller lipids. These findings help explain the experimentally observed or proposed differences in the insertion depth, binding strength, and structural transition of E and K peptides, and support the snorkeling effect.

All-atom simulations and free-energy calculations of coiled-coil peptides with lipid bilayers: binding strength, structural transition, and effect on lipid dynamics.

PubMed

Woo, Sun Young; Lee, Hwankyu

2016-03-01

Peptides E and K, which are synthetic coiled-coil peptides for membrane fusion, were simulated with lipid bilayers composed of lipids and cholesterols at different ratios using all-atom models. We first calculated free energies of binding from umbrella sampling simulations, showing that both E and K peptides tend to adsorb onto the bilayer surface, which occurs more strongly in the bilayer composed of smaller lipid headgroups. Then, unrestrained simulations show that K peptides more deeply insert into the bilayer with partially retaining the helical structure, while E peptides less insert and predominantly become random coils, indicating the structural transition from helices to random coils, in quantitative agreement with experiments. This is because K peptides electrostatically interact with lipid phosphates, as well as because hydrocarbons of lysines of K peptide are longer than those of glutamic acids of E peptide and thus form stronger hydrophobic interactions with lipid tails. This deeper insertion of K peptide increases the bilayer dynamics and a vacancy below the peptide, leading to the rearrangement of smaller lipids. These findings help explain the experimentally observed or proposed differences in the insertion depth, binding strength, and structural transition of E and K peptides, and support the snorkeling effect.

Quadrupole decay strength of the M1 scissors mode

NASA Astrophysics Data System (ADS)

Beck, T.; Beller, J.; Derya, V.; Gayer, U.; Isaak, J.; Löher, B.; Mertes, L.; Pietralla, N.; Ries, P.; Romig, C.; Savran, D.; Scheck, M.; Tornow, W.; Weller, H. R.; Werner, V.; Zweidinger, M.

2015-10-01

The E2/M1 multipole mixing ratio δ1→2 of the 1sc +→21+ transition of Gd was determined using results from high-statistics photon scattering. This provides a possibility for a new approach on the search of Jsc + members of the rotational band built on the scissors mode. By application of Alaga's rule, which is justifiable as 156Gd is a well-deformed rotor with good K quantum number, a transition strength of B (E 2 ;2sc +→01+)=0.034 (13 ) W.u. is estimated.

Phase transition studies of Na3Bi system under uniaxial strain

NASA Astrophysics Data System (ADS)

Nie, Tiaoping; Meng, Lijun; Li, Yanru; Luan, Yanhua; Yu, Jun

2018-03-01

We investigated the electronic properties and phase transitions of Na3Bi in four structural phases (space groups P63/mmc, P \\overline{3} c1, Fm \\overline{3} m and Cmcm) under constant-volume uniaxial strain using the first-principles method. For P63/mmc and P \\overline{3} c1-Na3Bi, an important phase transition from a topological Dirac semimetal (TDS) to a topological insulator appears under compression strain around 4.5%. The insulating gap increases with the increasing compressive strain and up to around 0.1 eV at a strain of 10%. However, both P63/mmc and P \\overline{3} c1-Na3Bi still keep the properties of a TDS within a tensile strain of 0-10%, although the Dirac points move away from the Γ point along Γ-A in reciprocal space as the tensile strain increases. The Na3Bi with space group Fm \\overline{3} m is identified as a topological semimetal with the inverted bands between Na-3s and Bi-6p and a parabolic dispersion in the vicinity of Γ point. Interestingly, for Fm \\overline{3} m-Na3Bi, both compression and tensile strain lead to a TDS which is identified by calculating surface Fermi arcs and topological invariants at time-reversal planes (k z   =  0 and k z   =  π/c) in reciprocal space. Additionally, we confirmed the high pressure phase Cmcm-Na3Bi is an ordinary insulator with a gap of about 0.62 eV. It is noteworthy that its gap almost keeps constant around 0.60 eV within a compression strain of 0-10%. In contrast, a remarkable phase transition from an insulator to a metal phase appears under tensile strain. Moreover, this phase transition is highly sensitive to tensile strain and takes place only at a strain 1.0%. These strain-induced electronic structures and phase transitions of the Na3Bi system in various phases are important due to their possible applications under high pressure in future electronic devices.

A Longitudinal Study into Indicators of Mental Health, Strengths and Difficulties Reported by Boarding Students as They Transition from Primary School to Secondary Boarding Schools in Perth, Western Australia

ERIC Educational Resources Information Center

Mander, David J.; Lester, Leanne

2017-01-01

This study examined indicators of mental health, as well as strengths and difficulties, as reported by same-age boarding and non-boarding students spanning four time points over a 2-year period as they transitioned from primary to boarding school in Western Australia (i.e., at the end of Grade 7, beginning of Grade 8, end of Grade 8, and end of…

Dynamic Transitions and Baroclinic Instability for 3D Continuously Stratified Boussinesq Flows

NASA Astrophysics Data System (ADS)

Şengül, Taylan; Wang, Shouhong

2018-02-01

The main objective of this article is to study the nonlinear stability and dynamic transitions of the basic (zonal) shear flows for the three-dimensional continuously stratified rotating Boussinesq model. The model equations are fundamental equations in geophysical fluid dynamics, and dynamics associated with their basic zonal shear flows play a crucial role in understanding many important geophysical fluid dynamical processes, such as the meridional overturning oceanic circulation and the geophysical baroclinic instability. In this paper, first we derive a threshold for the energy stability of the basic shear flow, and obtain a criterion for local nonlinear stability in terms of the critical horizontal wavenumbers and the system parameters such as the Froude number, the Rossby number, the Prandtl number and the strength of the shear flow. Next, we demonstrate that the system always undergoes a dynamic transition from the basic shear flow to either a spatiotemporal oscillatory pattern or circle of steady states, as the shear strength of the basic flow crosses a critical threshold. Also, we show that the dynamic transition can be either continuous or catastrophic, and is dictated by the sign of a transition number, fully characterizing the nonlinear interactions of different modes. Both the critical shear strength and the transition number are functions of the system parameters. A systematic numerical method is carried out to explore transition in different flow parameter regimes. In particular, our numerical investigations show the existence of a hypersurface which separates the parameter space into regions where the basic shear flow is stable and unstable. Numerical investigations also yield that the selection of horizontal wave indices is determined only by the aspect ratio of the box. We find that the system admits only critical eigenmodes with roll patterns aligned with the x-axis. Furthermore, numerically we encountered continuous transitions to multiple

Effective collision strengths for the electron impact excitation of Mg

NASA Astrophysics Data System (ADS)

Hudson, C. E.; Ramsbottom, C. A.; Norrington, P. H.; Scott, M. P.

2008-05-01

Electron impact excitation collision strengths for fine structure transitions of Mg,have been determined by a Breit-Pauli R-matrix calculation. The target states are represented by configuration interaction wavefunctions and consist of the 19 lowest LS states, having configurations 2s^22p^4, 2s2p^5, 2p^6, 2s^22p^33s and 2s^22p^33p. These target states give rise to 37 fine structure levels and 666 possible transitions. The effective collision strengths are calculated by averaging the electron collision strengths over a Maxwellian distribution of electron velocities. Effective collision strengths for transitions between the fine structure levels are given for electron temperatures in the range 10Te(K) = 3.0 - 7.0. Results are compared with the previous R-matrix calculation of Butler & Zeippen (AASS, 1994) and the recent Distorted Wave evaluations of Bhatia, Landi & Eissner (ADNDT, 2006).

X-ray Emission Spectroscopy in Magnetic 3d-Transition Metals

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

Iota, V; Park, J; Baer, B

2003-11-18

The application of high pressure affects the band structure and magnetic interactions in solids by modifying nearest-neighbor distances and interatomic potentials. While all materials experience electronic changes with increasing pressure, spin polarized, strongly electron correlated materials are expected to undergo the most dramatic transformations. In such materials, (d and f-electron metals and compounds), applied pressure reduces the strength of on-site correlations, leading to increased electron delocalization and, eventually, to loss of its magnetism. In this ongoing project, we study the electronic and magnetic properties of Group VIII, 3d (Fe, Co and Ni) magnetic transition metals and their compounds at highmore » pressures. The high-pressure properties of magnetic 3d-transition metals and compounds have been studied extensively over the years, because of iron being a major constituent of the Earth's core and its relevance to the planetary modeling to understand the chemical composition, internal structure, and geomagnetism. However, the fundamental scientific interest in the high-pressure properties of magnetic 3d-electron systems extends well beyond the geophysical applications to include the electron correlation-driven physics. The role of magnetic interactions in the stabilization of the ''non-standard'' ambient pressure structures of Fe, Co and Ni is still incompletely understood. Theoretical studies have predicted (and high pressure experiments are beginning to show) strong correlations between the electronic structure and phase stability in these materials. The phase diagrams of magnetic 3d systems reflect a delicate balance between spin interactions and structural configuration. At ambient conditions, the crystal structures of {alpha}-Fe(bcc) and {var_epsilon}-Co(hcp) phases depart from the standard sequence (hcp {yields} bcc{yields} hcp {yields} fcc), as observed in all other non-magnetic transition metals with increasing the d-band occupancy

Atomic data from the IRON Project. XXXII. On the accuracy of the effective collision strength for the electron impact excitation of the quadrupole transition in AR III

NASA Astrophysics Data System (ADS)

Galavís, M. E.; Mendoza, C.; Zeippen, C. J.

1998-12-01

Since te[Burgess et al. (1997)]{bur97} have recently questioned the accuracy of the effective collision strength calculated in the IRON Project for the electron impact excitation of the 3ssp23p sp4 \\ sp1 D -sp1 S quadrupole transition in Ar iii, an extended R-matrix calculation has been performed for this transition. The original 24-state target model was maintained, but the energy regime was increased to 100 Ryd. It is shown that in order to ensure convergence of the partial wave expansion at such energies, it is necessary to take into account partial collision strengths up to L=30 and to ``top-up'' with a geometric series procedure. By comparing effective collision strengths, it is found that the differences from the original calculation are not greater than 25% around the upper end of the common temperature range and that they are much smaller than 20% over most of it. This is consistent with the accuracy rating (20%) previously assigned to transitions in this low ionisation system. Also the present high-temperature limit agrees fairly well (15%) with the Coulomb-Born limit estimated by Burgess et al., thus confirming our previous accuracy rating. It appears that Burgess et al., in their data assessment, have overextended the low-energy behaviour of our reduced effective collision strength to obtain an extrapolated high-temperature limit that appeared to be in error by a factor of 2.

Calculations for energies, transition rates, and lifetimes in Al-like Kr XXIV

NASA Astrophysics Data System (ADS)

Zhang, C. Y.; Si, R.; Liu, Y. W.; Yao, K.; Wang, K.; Guo, X. L.; Li, S.; Chen, C. Y.

2018-05-01

Using the second-order many-body perturbation theory (MBPT) method, a complete and accurate data set of excitation energies, lifetimes, wavelengths, and electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) line strengths, transition rates, and oscillator strengths for the lowest 880 levels arising from the 3l3 (0 ≤ l ≤ 2), 3l2 4l‧ (0 ≤ l ≤ 2, 0 ≤l‧ ≤ 3), 3s2 5 l (0 ≤ l ≤ 4), 3p2 5 l (0 ≤ l ≤ 1), and 3s3p5 l (0 ≤ l ≤ 4) configurations in Al-like Kr XXIV is provided. Comparisons are made with available experimental and theoretical results. Our calculated energies are expected to be accurate enough to facilitate identifications of observed lines involving the n = 4 , 5 levels. The complete data set is also useful for modeling and diagnosing fusion plasma.

Phase transition and strength of vanadium under shock compression up to 88 GPa

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

Yu, Yuying, E-mail: yuyinyu@caep.cn; Tan, Ye; Dai, Chengda

A series of reverse-impact experiments were performed on vanadium at shock pressure ranging from 32 GPa to 88 GPa. Particle velocity profiles measured at sample/LiF window interface were used to estimate the sound velocities, shear modulus, and yield stress in shocked vanadium. A phase transition at ∼60.5 GPa that may be the body-centered cubic (BCC) to rhombohedral structure was identified by the discontinuity of the sound velocity against shock pressure. This transition pressure is consistent with the results from diamond anvil cell (DAC) experiments and first-principle calculations. However, present results show that the rhombohedral phase has higher strength and shear modulus than themore » BCC phase, which is contrast to the findings from DAC experiments and theoretical work.« less

PVAST Propeller Vibration and Strength Analysis Program Version 7.3 User’s Manual

DTIC Science & Technology

2001-03-01

Copy No: ___ _ PVAST Propeller Vibration and Strength Analysis Program Version 7.3 User’s Manual Koko ,T S, Palmeter, M F, Chernuka, M.W. MARTEC...34St name, rruddle mittal If rruhtary, show rank, e g. Doe, Maj. John E.) Koko ,T.S., Palmeter, M.F., Chernuka, M.W. DATE OF PUBLICATION (month and

Strengths-based positive psychology interventions: a randomized placebo-controlled online trial on long-term effects for a signature strengths- vs. a lesser strengths-intervention.

PubMed

Proyer, René T; Gander, Fabian; Wellenzohn, Sara; Ruch, Willibald

2015-01-01

Recent years have seen an increasing interest in research in positive psychology interventions. There is broad evidence for their effectiveness in increasing well-being and ameliorating depression. Intentional activities that focus on those character strengths, which are most typical for a person (i.e., signature strengths, SS) and encourage their usage in a new way have been identified as highly effective. The current study aims at comparing an intervention aimed at using SS with one on using individual low scoring (or lesser) strengths in a randomized placebo-controlled trial. A total of 375 adults were randomly assigned to one of the two intervention conditions [i.e., using five signature vs. five lesser strengths (LS) in a new way] or a placebo control condition (i.e., early memories). We measured happiness and depressive symptoms at five time points (i.e., pre- and post-test, 1-, 3-, and 6-months follow-ups) and character strengths at pre-test. The main findings are that (1) there were increases in happiness for up to 3 months and decreases in depressive symptoms in the short term in both intervention conditions; (2) participants found working with strengths equally rewarding (enjoyment and benefit) in both conditions; (3) those participants that reported generally higher levels of strengths benefitted more from working on LS rather than SS and those with comparatively lower levels of strengths tended to benefit more from working on SS; and (4) deviations from an average profile derived from a large sample of German-speakers completing the Values-in-Action Inventory of Strengths were associated with greater benefit from the interventions in the SS-condition. We conclude that working on character strengths is effective for increasing happiness and discuss how these interventions could be tailored to the individual for promoting their effectiveness.

Transit Recovery of Kepler-167e: Providing JWST with an Unprecedented Jupiter-analog Exoplanet Target

NASA Astrophysics Data System (ADS)

Dalba, Paul; Muirhead, Philip; Tamburo, Patrick

2018-05-01

The Kepler Mission has uncovered a handful of long-period transiting exoplanets that orbit in the cold outer reaches of their systems, despite their low transit probabilities. Recent work suggests that cold gas giant exoplanet atmospheres are amenable to transmission spectroscopy (the analysis of the transit depth versus wavelength) enabling novel tests of planetary formation and evolution theories. Of particular scientific interest is Kepler-167e, a low-eccentricity Jupiter-analog exoplanet with a 1,071-day orbital period residing well beyond the snow-line. Transmission spectroscopy of Kepler-167e from JWST can reveal the composition of this planet's atmosphere, constrain its heavy-element abundance, and identify atmospheric photochemical processes. JWST characterization also enables unprecedented direct comparison with Jupiter and Saturn, which show a striking diversity in physical properties that is best investigated through comparative exoplanetology. Since Kepler only observed two transits of Kepler-167e, it is not known if this exoplanet exhibits transit timing variations (TTVs). About half of Kepler's long-period exoplanets have TTVs of up to 40 hours. Such a large uncertainty jeopardizes attempts to characterize the atmosphere of this unique Jovian exoplanet with JWST. To mitigate this risk, the upcoming third transit of Kepler-167e must be observed to test for TTVs. We propose a simple 10-hour, single-channel observation to capture ingress or egress of the next transit of Kepler-167e in December 2018. In the absence of TTVs, our observation will reduce the ephemeris uncertainty from an unknown value to approximately 3 minutes, thereby removing the risk in future transit observations with JWST. The excellent photometric precision of Spitzer is sufficient to identify the transit of Kepler-167e. Given the timing and nature of this program, Spitzer is the only observatory--on the ground or in space--that can make this pivotal observation.

Causal strength induction from time series data.

PubMed

Soo, Kevin W; Rottman, Benjamin M

2018-04-01

One challenge when inferring the strength of cause-effect relations from time series data is that the cause and/or effect can exhibit temporal trends. If temporal trends are not accounted for, a learner could infer that a causal relation exists when it does not, or even infer that there is a positive causal relation when the relation is negative, or vice versa. We propose that learners use a simple heuristic to control for temporal trends-that they focus not on the states of the cause and effect at a given instant, but on how the cause and effect change from one observation to the next, which we call transitions. Six experiments were conducted to understand how people infer causal strength from time series data. We found that participants indeed use transitions in addition to states, which helps them to reach more accurate causal judgments (Experiments 1A and 1B). Participants use transitions more when the stimuli are presented in a naturalistic visual format than a numerical format (Experiment 2), and the effect of transitions is not driven by primacy or recency effects (Experiment 3). Finally, we found that participants primarily use the direction in which variables change rather than the magnitude of the change for estimating causal strength (Experiments 4 and 5). Collectively, these studies provide evidence that people often use a simple yet effective heuristic for inferring causal strength from time series data. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Relativistic distorted-wave collision strengths for Δn = 0 transitions in the 67 Li-like, F-like and Na-like ions with 26 ≤ Z ≤ 92

NASA Astrophysics Data System (ADS)

Fontes, Christopher J.; Zhang, Hong Lin

2017-01-01

Relativistic distorted-wave collision strengths have been calculated for all possible Δn = 0 transitions, where n denotes the valence shell of the ground level, in the 67 Li-like, F-like and Na-like ions with Z in the range 26 ≤ Z ≤ 92. This choice produces 3 transitions with n = 2 in the Li-like and F-like ions, and 10 transitions with n = 3 in the Na-like ions. For the Li-like and F-like ions, the calculations were made for the six final, or scattered, electron energies E‧ = 0.008 , 0.04 , 0.10 , 0.21 , 0.41, and 0.75, where E‧ is in units of Zeff2 Ry with Zeff = Z - 1.66 for Li-like ions and Zeff = Z - 6.667 for F-like ions. For the Na-like ions, the calculations were made for the six final electron energies E‧ = 0.0025 , 0.015 , 0.04 , 0.10 , 0.21, and 0.40, with Zeff = Z - 8.34. In the present calculations, an improved "top-up" method, which employs relativistic plane waves, was used to obtain the high partial-wave contribution for each transition, in contrast to the partial-relativistic Coulomb-Bethe approximation used in previous works by Zhang, Sampson and Fontes [H.L. Zhang, D.H. Sampson, C.J. Fontes, At. Data Nucl. Data Tables 44 (1990) 31; H.L. Zhang, D.H. Sampson, C.J. Fontes, At. Data Nucl. Data Tables 48 (1991) 25; D.H. Sampson, H.L. Zhang, C.J. Fontes, At. Data Nucl. Data Tables 44 (1990) 209]. In those previous works, collision strengths were also provided for Li-, F- and Na-like ions, but for a more comprehensive set of transitions. The collision strengths covered in the present work should be more accurate than the corresponding data given in those previous works and are presented here to replace those earlier results.

The SU(3)/Z3 QCD(adj) deconfinement transition via the gauge theory/"affine" XY-model duality

NASA Astrophysics Data System (ADS)

Anber, Mohamed M.; Collier, Scott; Poppitz, Erich

2013-01-01

Earlier, two of us and M. Ünsal [1] showed that a class of 4d gauge theories, when compactified on a small spatial circle of size L and considered at temperatures β-1 near the deconfinement transition, are dual to 2d "affine" XY-spin models. We exploit this duality to study the deconfinement phase transition in SU(3)/{{{Z}}_3} gauge theories with n f > 1 massless adjoint Weyl fermions, QCD(adj) on {{{R}}^2}× {S}_{β}^1× {S}_L^1 . The dual "affine" XY-model describes two "spins" — compact scalars taking values in the SU(3) root lattice. The spins couple via nearest-neighbor interactions and are subject to an "external field" perturbation preserving the topological {Z}_3^t and a discrete {Z}_3^{{{d_{\\upchi}}}} subgroup of the anomaly-free chiral symmetry of the 4d gauge theory. The equivalent Coulomb gas representation of the theory exhibits electric-magnetic duality, which is also a high-/low-temperature duality. A renormalization group analysis suggests — but is not convincing, due to the onset of strong coupling — that the self-dual point is a fixed point, implying a continuous deconfinement transition. Here, we study the nature of the transition via Monte Carlo simulations. The {Z}_3^t× {Z}_3^{{{d_{\\upchi}}}} order parameter, its susceptibility, the vortex density, the energy per spin, and the specific heat are measured over a range of volumes, temperatures, and "external field" strengths (in the gauge theory, these correspond to magnetic bion fugacities). The finite-size scaling of the susceptibility and specific heat we find is characteristic of a first-order transition. Furthermore, for sufficiently large but still smaller than unity bion fugacity (as can be achieved upon an increase of the {S}_L^1 size), at the critical temperature we find two distinct peaks of the energy probability distribution, indicative of a first-order transition, as has been seen in earlier simulations of the full 4d QCD(adj) theory. We end with discussions of the global

Oxidation Behavior of Matrix Graphite and Its Effect on Compressive Strength

DOE PAGES

Zhou, Xiangwen; Contescu, Cristian I.; Zhao, Xi; ...

2017-01-01

Mmore » atrix graphite (G) with incompletely graphitized binder used in high-temperature gas-cooled reactors (HTGRs) is commonly suspected to exhibit lower oxidation resistance in air. In order to reveal the oxidation performance, the oxidation behavior of newly developed A3-3 G at the temperature range from 500 to 950°C in air was studied and the effect of oxidation on the compressive strength of oxidized G specimens was characterized. Results show that temperature has a significant influence on the oxidation behavior of G. The transition temperature between Regimes I and II is ~700°C and the activation energy ( E a ) in Regime I is around 185 kJ/mol, a little lower than that of nuclear graphite, which indicates G is more vulnerable to oxidation. Oxidation at 550°C causes more damage to compressive strength of G than oxidation at 900°C. Comparing with the strength of pristine G specimens, the rate of compressive strength loss is 77.3% after oxidation at 550°C and only 12.5% for oxidation at 900°C. icrostructure images of SE and porosity measurement by ercury Porosimetry indicate that the significant compressive strength loss of G oxidized at 550°C may be attributed to both the uniform pore formation throughout the bulk and the preferential oxidation of the binder.« less

Transition and Electron Impact Excitation Collision Rates for O III

NASA Astrophysics Data System (ADS)

Tayal, S. S.; Zatsarinny, O.

2017-12-01

Transition probabilities, electron excitation collision strengths, and rate coefficients for a large number of O III lines over a broad wavelength range, from the infrared to ultraviolet, have been reported. The collision strengths have been calculated in the close-coupling approximation using the B-spline Breit-Pauli R-matrix method. The multiconfiguration Hartree-Fock method in combination with B-spline expansions is employed for an accurate representation of the target wave functions. The close-coupling expansion contains 202 O2+ fine-structure levels of the 2{s}22{p}2,2s2{p}3, 2{p}4,2{s}22p3s,3p,3d, 4s,4p,4d,4f,5s, and 2s2{p}33s,3p,3d configurations. The effective collision strengths are obtained by averaging electron excitation collision strengths over a Maxwellian distribution of velocities at electron temperatures ranging from 100 to 100,000 K. The calculated effective collision strengths have been reported for the 20,302 transitions between all 202 fine-structure levels. There is an overall good agreement with the recent R-matrix calculations by Storey et al. for the transitions between all levels of the ground 2{s}22{p}2 configuration, but significant discrepancies have been found with Palay et al. for transitions to the 2{s}22{p}2 1 S 0 level. Line intensity ratios between the optical lines arising from the 2{s}22{p}2{}3{P}{0,1,2} - 1 D 2 transitions have been compared with other calculations and observations from the photoionized gaseous nebulae, and good agreement is found. The present calculations provide the most complete and accurate data sets, which should allow a more detailed treatment of the available measured spectra from different ground and space observatories.

Electric Quadrupole E2- Transitions of 170-174 Yb Isotopes

NASA Astrophysics Data System (ADS)

Abu El Sheikh, Mohd Kh. M.; Okhunov, Abdurahim A.; Usmanov, Ph. N.; Hassan, Torla HJ

2017-12-01

The non-adiabatic effects which is manifested in the electric properties of low-lying states of even-even deformed nuclei are studied. A simple phenomenological model which takes into account the Coriolis mixing of {K}π ={0}n+,{2}n+ and {K}π ={1}ν + state bands. The Calculations for isotopes 170-174 Yb, are carried out. The reduced probability of electric quadrupole transitions from the states {0}ν + and {2}ν + - bands to the ground (gr) state band is calculated and non adiabatic effect is discussed. The ratio of E2- transitions RIK from {0}2+, {0}3+, {2}1+, and {2}2+ bands are calculated and compared with the experimental data.

Electron impact collision strengths in Ne VII

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

Di, L.; Shi, J.R.; Zhao, G., E-mail: gzhao@bao.ac.cn

2012-07-15

The lines of Ne VII have been observed in many astronomical objects, and some transitions from high energy levels were observed both in Seyfert galaxies and stellar coronae. Thus, the atomic data for these transitions are important for modeling. Using the code FAC we calculated the collision strengths based on the distorted-wave method with large configuration interactions included. The Maxwellian averaged effective collision strengths covering the typical temperature range of astronomical and laboratory hot plasmas are presented. We extend the calculation of the energy levels to n=4 and 5. The energy levels, wavelengths, spontaneous transition rates, weighted oscillator strengths, andmore » effective collision strengths were reported. Compared with the results from experiment or previous theoretical calculations a general agreement is found. It is found that the resonance effects are important in calculating the effective collision strengths.« less

Fatigue strength reduction model: RANDOM3 and RANDOM4 user manual, appendix 2

NASA Technical Reports Server (NTRS)

Boyce, Lola; Lovelace, Thomas B.

1989-01-01

The FORTRAN programs RANDOM3 and RANDOM4 are documented. They are based on fatigue strength reduction, using a probabilistic constitutive model. They predict the random lifetime of an engine component to reach a given fatigue strength. Included in this user manual are details regarding the theoretical backgrounds of RANDOM3 and RANDOM4. Appendix A gives information on the physical quantities, their symbols, FORTRAN names, and both SI and U.S. Customary units. Appendix B and C include photocopies of the actual computer printout corresponding to the sample problems. Appendices D and E detail the IMSL, Version 10(1), subroutines and functions called by RANDOM3 and RANDOM4 and SAS/GRAPH(2) programs that can be used to plot both the probability density functions (p.d.f.) and the cumulative distribution functions (c.d.f.).

Where Is the Electronic Oscillator Strength? Mapping Oscillator Strength across Molecular Absorption Spectra.

PubMed

Zheng, Lianjun; Polizzi, Nicholas F; Dave, Adarsh R; Migliore, Agostino; Beratan, David N

2016-03-24

The effectiveness of solar energy capture and conversion materials derives from their ability to absorb light and to transform the excitation energy into energy stored in free carriers or chemical bonds. The Thomas-Reiche-Kuhn (TRK) sum rule mandates that the integrated (electronic) oscillator strength of an absorber equals the total number of electrons in the structure. Typical molecular chromophores place only about 1% of their oscillator strength in the UV-vis window, so individual chromophores operate at about 1% of their theoretical limit. We explore the distribution of oscillator strength as a function of excitation energy to understand this circumstance. To this aim, we use familiar independent-electron model Hamiltonians as well as first-principles electronic structure methods. While model Hamiltonians capture the qualitative electronic spectra associated with π electron chromophores, these Hamiltonians mistakenly focus the oscillator strength in the fewest low-energy transitions. Advanced electronic structure methods, in contrast, spread the oscillator strength over a very wide excitation energy range, including transitions to Rydberg and continuum states, consistent with experiment. Our analysis rationalizes the low oscillator strength in the UV-vis spectral region in molecules, a step toward the goal of oscillator strength manipulation and focusing.

Strength functions, entropies, and duality in weakly to strongly interacting fermionic systems.

PubMed

Angom, D; Ghosh, S; Kota, V K B

2004-01-01

We revisit statistical wave function properties of finite systems of interacting fermions in the light of strength functions and their participation ratio and information entropy. For weakly interacting fermions in a mean-field with random two-body interactions of increasing strength lambda, the strength functions F(k) (E) are well known to change, in the regime where level fluctuations follow Wigner's surmise, from Breit-Wigner to Gaussian form. We propose an ansatz for the function describing this transition which we use to investigate the participation ratio xi(2) and the information entropy S(info) during this crossover, thereby extending the known behavior valid in the Gaussian domain into much of the Breit-Wigner domain. Our method also allows us to derive the scaling law lambda(d) approximately 1/sqrt[m] ( m is number of fermions) for the duality point lambda= lambda(d), where F(k) (E), xi(2), and S(info) in both the weak ( lambda=0 ) and strong mixing ( lambda= infinity ) basis coincide. As an application, the ansatz function for strength functions is used in describing the Breit-Wigner to Gaussian transition seen in neutral atoms CeI to SmI with valence electrons changing from 4 to 8.

Anderson transition in a multiply-twisted helix.

PubMed

Ugajin, R

2001-06-01

We investigated the Anderson transition in a multiply-twisted helix in which a helical chain of components, i.e., atoms or nanoclusters, is twisted to produce a doubly-twisted helix, which itself can be twisted to produce a triply-twisted helix, and so on, in which there are couplings between adjacent rounds of helices. As the strength of the on-site random potentials increases, an Anderson transition occurs, suggesting that the number of dimensions is 3 for electrons running along the multiply-twisted helix when the couplings between adjacent rounds are strong enough. If the couplings are weakened, the dimensionality becomes less, resulting in localization of electrons. The effect of random connections between adjacent rounds of helices and random magnetic fields that thread the structure is analyzed using the spectral statistics of a quantum particle.

Extensive computation of allowed and forbidden transition probabilities in the potassium isoelectronic sequence

NASA Astrophysics Data System (ADS)

Dixit, Gopal; Deshmukh, Pranawa C.; Manson, Steven T.; Majumder, Sonjoy

2007-06-01

Our primary aim in this work is to present both allowed and forbidden transition amplitudes and corresponding wavelengths and oscillator strengths for a few ions in the 19-electron potassium isoelectronic sequence. All of these ions have the configuration [Ar] 3^2D3/2 as their ground state, except in the case of K and Ca^+, where it is [Ar] 4^2S1/2.This difference in ground state configuration arises due to strong contributions of correlation effects in the energy levels of these systems [1]. Allowed and forbidden transitions in these systems are of great importance in astrophysics [2] and in laboratory plasma research [3]. We apply in the present work the relativistic coupled-cluster (RCC) theory [4] to evaluate the energy levels and wave functions of these systems and study amplitudes for electric and magnetic dipole transition amplitudes and also the electric quadrupole transition amplitudes. The contributions of various electron correlation effects to the transition amplitudes are estimated in some detail using the RCC theory. [1] Gopal Dixit et al., Astrophys. J (submitted); arXiv.org: physics/0702066. [2] C. R. Cowley and G. M. Wahlgern, Astronomy & Astrophysics, 447, 681 (2002). [3] J. E. Vernazza, E. M. Reeves, Astrophys. J. Suppl. 37, 485 (1978) [4] I. Lindgren, Physics Scripta, 36, 591 (1987).

Doubly magic 208Pb: High-spin states, isomers, and E 3 collectivity in the yrast decay

NASA Astrophysics Data System (ADS)

Broda, R.; Janssens, R. V. F.; Iskra, Ł. W.; Wrzesinski, J.; Fornal, B.; Carpenter, M. P.; Chiara, C. J.; Cieplicka-Oryńczak, N.; Hoffman, C. R.; Kondev, F. G.; Królas, W.; Lauritsen, T.; Podolyak, Zs.; Seweryniak, D.; Shand, C. M.; Szpak, B.; Walters, W. B.; Zhu, S.; Brown, B. A.

2017-06-01

Yrast and near-yrast levels up to spin values in excess of I =30 ℏ have been delineated in the doubly magic 208Pb nucleus following deep-inelastic reactions involving 208Pb targets and, mostly, 430-MeV 48Ca and 1440-MeV 208Pb beams. The level scheme was established up to an excitation energy of 16.4 MeV, based on multifold γ-ray coincidence relationships measured with the Gammasphere array. Below the well-known, 0.5-μs 10+ isomer, ten new transitions were added to earlier work. The delineation of the higher parts of the level sequence benefited from analyses involving a number of prompt- and delayed-coincidence conditions. Three new isomeric states were established along the yrast line with Iπ=20- (10 342 keV), 23+ (11 361 keV), and 28- (13 675 keV), and respective half-lives of 22(3), 12.7(2), and 60(6) ns. Gamma transitions were also identified preceding in time the 28- isomer; however, only a few could be placed in the level scheme and no firm spin-parity quantum numbers could be proposed. In contrast, for most states below this 28- isomer, firm spin-parity values were assigned, based on total electron-conversion coefficients, deduced for low-energy (<500 keV ) transitions from γ-intensity balances, and on measured γ-ray angular distributions. The latter also enabled the quantitative determination of mixing ratios. The transition probabilities extracted for all isomeric transitions in 208Pb have been reviewed and discussed in terms of the intrinsic structure of the initial and final levels involved. Particular emphasis was placed on the many observed E 3 transitions as they often exhibit significant enhancements in strength [of the order of tens of Weisskopf units (W.u.)] comparable to the one seen for the neutron j15 /2→g9 /2 E 3 transition in 209Pb. In this context, the enhancement of the 725-keV E 3 transition (56 W.u.) associated with the decay of the highest-lying 28- isomer observed in this work remains particularly challenging to explain. Large

FOUR WAVE MIXING SPECTROSCOPY OF THE NO_3 tilde{B} ^2E' - tilde{X} ^2A_2' transition

NASA Astrophysics Data System (ADS)

Fukushima, Masaru; Ishiwata, Takashi

2014-06-01

The tilde{B} ^2E' - tilde{X} ^2A_2' electronic transition of NO_3 generated in a supersonic free jet expansion was investigated by four wave mixing ( 4WM ) spectroscopy. The degenerated 4WM and laser induced fluorescence ( LIF ) spectra around the 0_0^0 band region were measured simultaneously. The D4WM spectrum shows broad band features for the 0_0^0 band similar to that of the LIF spectrum. The broad 0_0^0 band does not consist of one sub-band, but of several bands. The intensity distribution of the sub-bands of the D4WM spectrum is similar, but not identical to that of the LIF spectrum.

Oscillator strengths and collision strengths for S v

NASA Technical Reports Server (NTRS)

Van Wyngaarden, W. L.; Henry, R. J. W.

1981-01-01

Observations of the optical extreme-ultraviolet spectrum of the Jupiter planetary system during the Voyager space mission revealed bright emission lines of some sulfur ions. The spectra of the torus at the orbit of Io are likely to contain S V lines. The described investigation provides oscillator strengths and collision strengths for the first four UV lines. The collision strengths from the ground state to four other excited states are also obtained. Use is made of a two-state calculation which is checked for convergence for some transitions by employing a three-state or a four-state approximation. Target wave functions for S V are calculated so that the oscillator strengths calculated in dipole length and dipole velocity approximations agree within 5%.

Excitation rates for transitions in Kr XXXII

NASA Astrophysics Data System (ADS)

Aggarwal, K. M.; Keenan, F. P.; Lawson, K. D.

2009-04-01

In this paper we report our results for collision strengths and effective collision strengths for transitions among the lowest 125 levels of the 2s22p, 2s2p2, 2p3, 2s23ell, 2s2p3ell, and 2p23ell configurations of Kr XXXII. For our calculations both the FAC and DARC codes have been employed.

Energy Levels, Lifetimes, and Transition Rates for P-like Ions from Cr X to Zn XVI from Large-scale Relativistic Multiconfiguration Calculations

NASA Astrophysics Data System (ADS)

Wang, K.; Jönsson, P.; Gaigalas, G.; Radžiūtė, L.; Rynkun, P.; Del Zanna, G.; Chen, C. Y.

2018-04-01

The fully relativistic multiconfiguration Dirac–Hartree–Fock method is used to compute excitation energies and lifetimes for the 143 lowest states of the 3{s}23{p}3, 3s3p 4, 3{s}23{p}23d, 3s3p 33d, 3p 5, 3{s}23p3{d}2 configurations in P-like ions from Cr X to Zn XVI. Multipole (E1, M1, E2, M2) transition rates, line strengths, oscillator strengths, and branching fractions among these states are also given. Valence–valence and core–valence electron correlation effects are systematically accounted for using large basis function expansions. Computed excitation energies are compared with the NIST ASD and CHIANTI compiled values and previous calculations. The mean average absolute difference, removing obvious outliers, between computed and observed energies for the 41 lowest identified levels in Fe XII, is only 0.057%, implying that the computed energies are accurate enough to aid identification of new emission lines from the Sun and other astrophysical sources. The amount of energy and transition data of high accuracy are significantly increased for several P-like ions of astrophysics interest, where experimental data are still very scarce.

Effect of etching time and resin bond on the flexural strength of IPS e.max Press glass ceramic.

PubMed

Xiaoping, Luo; Dongfeng, Ren; Silikas, Nick

2014-12-01

To evaluate the effect of hydrofluoric acid (HFA) etching time and resin cement bond on the flexural strength of IPS e.max(®) Press glass ceramic. Two hundred and ten bars, 25mm×3mm×2mm, were made from IPS e.max(®) Press ingots through lost-wax, hot-pressed ceramic fabrication technology and randomly divided into five groups with forty-two per group after polishing. The ceramic surfaces of different groups were etched by 9.5% hydrofluoric acid gel for 0, 20, 40, 60 and 120s respectively. Two specimens of each group were selected randomly to examine the surface roughness and 3-dimensional topography with atomic force microscope (AFM), and microstructure was analyzed by the field emission scanning electron microscope (FE-SEM). Then each group were subdivided into two subgroups (n=20). One subgroup of this material was selected to receive a thin (approximately 0.1mm) layer of resin luting agent (Variolink N) whereas the other subgroup remained unaltered. Half of subgroup's specimens were thermocycled 10,000 times before a 3-point bending test in order to determine the flexural strength. Interface between resin cement and ceramic was examined with field emission scanning electronic microscope. Roughness values increased with increasing etching time. The mean flexural strength values of group 0s, 20s, 40s, 60s and 120s were 384±33, 347±43, 330±53, 327±67 and 317±41MPa respectively. Increasing HF etching times reduced the mean flexural strength (p<0.05). However, the mean flexural strength of each group, except group 0s, increased significantly to 420±31, 435±50, 400±39 and 412±58MPa after the application of dual-curing resin cement. In the present investigation, no significant differences after thermocycling on the flexural strengths were evident. Overtime HF etching could have a wakening effect on IPS e.max(®) Press glass ceramic, but resin cement bonding to appropriately etched surface would strengthen the dental ceramic. Copyright © 2014 Academy of

Equation of motion approach for describing allowed transitions in Ne and Al3+ under classical and quantum plasmas

NASA Astrophysics Data System (ADS)

Chaudhuri, Supriya K.; Mukherjee, Prasanta K.; Chaudhuri, Rajat K.; Chattopadhyay, Sudip

2018-04-01

The equation of motion coupled cluster methodology within relativistic framework has been applied to analyze the electron correlation effects on the low lying dipole allowed excited states of Ne and Al3+ under classical and quantum plasma environments. The effect of confinement due to classical plasma has been incorporated through screened Coulomb potential, while that of quantum plasma has been treated by exponential cosine screened Coulomb potential. The confined structural properties investigated are the depression of ionization potential, low lying excitation energies (dipole allowed), oscillator strengths, transition probabilities, and frequency dependent polarizabilities under systematic variation of the plasma-atom coupling strength determined through the screening parameter. Specific atomic systems are chosen for their astrophysical importance and availability of experimental data related to laboratory plasma with special reference to Al3+ ion. Here, we consider 1 s22 s22 p6(1S0)→1 s22 s22 p5 n s /n d (1P1) (n =3 ,4 ) dipole allowed transitions of Ne and Al3+. Results for the free (isolated) atomic systems agree well with those available in the literature. Spectroscopic properties under confinement show systematic and interesting pattern with respect to plasma screening parameter.

CI+MBPT calculations of Ar I energies, g factors, and transition line strengths

NASA Astrophysics Data System (ADS)

Savukov, I. M.

2018-03-01

Excited states of noble gas atoms present certain challenges to atomic theory for several reasons: first, relativistic effects are important and LS coupling is not optimal; second, energy intervals can be quite small, leading to strong mixing of states; third, many-body perturbation theory for hole states does not converge well. Previously, some attempts were made to solve this problem, using for example the all-order coupled-cluster approach and particle-hole configuration-interaction many-body perturbation theory (CI-MBPT) with modified denominators. However, while these approaches were promising, the accuracy was still limited. In this paper, we calculate Ar I energies, g factors, and transition amplitudes using ab initio CI-MBPT with eight valence electrons to avoid the problem of slow convergence of MBPT due to strong interaction between 3p and 3s states. We also included in CI many dominant states obtained by double excitations of the ground state configuration. Thus perturbation corrections were needed only for 1s, 2s, 2p core electrons non-included in valence-valence CI, which are quite small. We found that energy, g factors, and electric dipole matrix elements are in reasonable agreement with experiments. It is noteworthy that the theory agreed well with accurately measured g factors. Experimental oscillator strengths have large uncertainty, so in some cases we made a comparison with average values.

Optical and Photophysical Investigation of (2E)-1-(2,5-Dimethylfuran-3-Yl)-3-(9-Ethyl-9H-Carbazol-3-Yl)Prop-2-en-1-One (DEPO) by Spectrofluorometer in Organized Medium.

PubMed

Asiri, Abdullah M; Al-Dies, Al-Anood M; Khan, Salman A

2017-07-01

(2E)-1-(2,5-dimethylfuran-3-yl)-3-(9-ethyl-9H-carbazol-3-yl)prop-2-en-1-one (DEPO) was prepared by the reaction of 9-ethyl-9H-carbazole-3-carbaldehyde with 1-(2,5-dimethylfuran-3-yl)ethanone under microwave irradiation. The structure of DEPO was established experimentally by EI-MS, FT-IR, 1 H and 13 C NMR spectral studies. Electronic absorption and emission spectra of DEPO were studied in different solvents on the basis of polarities, and the obtain data were used to determine the solvatochromic properties such as extinction coefficient, oscillator strength, transition dipole moment, stokes shift, fluorescence quantum yield and photochemical quantum yield. Photochemical quantum yield (Φ c ) of DEPO dye was determined in different solvent. The dye comparatively photostable in DMSO but undergoes photodecomposition in chloro methane solvents. The DEPO dye may be use as probe or quencher to determine critical micelle concentration (CMC) of cetyltri methyl ammonium bromide (CTAB) and sodium dodecyl sulfate (SDS).

14-3-3ε Overexpression Contributes to Epithelial-Mesenchymal Transition of Hepatocellular Carcinoma

PubMed Central

Liang, Shu-Man; Chen, Shyh-Chang; Wang, John; Hsu, Chiun; Wu, Yao-Ming; Liou, Jun-Yang

2013-01-01

Background 14-3-3ε is implicated in regulating tumor progression, including hepatocellular carcinoma (HCC). Our earlier study indicated that elevated 14-3-3ε expression is significantly associated with higher risk of metastasis and lower survival rates of HCC patients. However, the molecular mechanisms of how 14-3-3ε regulates HCC tumor metastasis are still unclear. Methodology and Principal Findings In this study, we show that increased 14-3-3ε expression induces HCC cell migration and promotes epithelial-mesenchymal transition (EMT), which is determined by the reduction of E-cadherin expression and induction of N-cadherin and vimentin expression. Knockdown with specific siRNA abolished 14-3-3ε-induced cell migration and EMT. Furthermore, 14-3-3ε selectively induced Zeb-1 and Snail expression, and 14-3-3ε-induced cell migration was abrogated by Zeb-1 or Snail siRNA. In addition, the effect of 14-3-3ε-reduced E-cadherin was specifically restored by Zeb-1 siRNA. Positive 14-3-3ε expression was significantly correlated with negative E-cadherin expression, as determined by immunohistochemistry analysis in HCC tumors. Analysis of 14-3-3ε/E-cadherin expression associated with clinicopathological characteristics revealed that the combination of positive 14-3-3ε and negative E-cadherin expression is significantly correlated with higher incidence of HCC metastasis and poor 5-year overall survival. In contrast, patients with positive 14-3-3ε and positive E-cadherin expression had better prognostic outcomes than did those with negative E-cadherin expression. Significance Our findings show for the first time that E-cadherin is one of the downstream targets of 14-3-3ε in modulating HCC tumor progression. Thus, 14-3-3ε may act as an important regulator in modulating tumor metastasis by promoting EMT as well as cell migration, and it may serve as a novel prognostic biomarker or therapeutic target for HCC. PMID:23483955

Energy levels and radiative rates for transitions in Co XI

NASA Astrophysics Data System (ADS)

Aggarwal, K. M.; Keenan, F. P.; Msezane, A. Z.

2007-10-01

Aims: In this paper we report calculations for energy levels and radiative rates for transitions in Co xi. Methods: The General purpose Relativistic Atomic Structure Package (grasp) and the Flexible Atomic Code (fac) have been adopted for the calculations of energy levels and radiative rates. Results: Energies for the lowest 287 levels of Co xi, including those among the (1s^22s^22p^6) 3s^23p^5, 3s3p^6, 3s^23p^43d, 3s3p^53d, 3s^23p^33d^2, and 3s^23p^44s configurations, are reported. Additionally, radiative rates and oscillator strengths are reported for all electric dipole (E1) transitions with f ≥ 10-5 among these levels, and similar results for magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) transitions are reported only for those with f≥10-8. Comparisons are made with the available results in the literature, and the accuracy of the present data is assessed. Finally, lifetimes for all excited levels are also listed, although measurements are presently available for only one of these. Tables 1 and 3-6 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/473/995

High-strength cellular ceramic composites with 3D microarchitecture.

PubMed

Bauer, Jens; Hengsbach, Stefan; Tesari, Iwiza; Schwaiger, Ruth; Kraft, Oliver

2014-02-18

To enhance the strength-to-weight ratio of a material, one may try to either improve the strength or lower the density, or both. The lightest solid materials have a density in the range of 1,000 kg/m(3); only cellular materials, such as technical foams, can reach considerably lower values. However, compared with corresponding bulk materials, their specific strength generally is significantly lower. Cellular topologies may be divided into bending- and stretching-dominated ones. Technical foams are structured randomly and behave in a bending-dominated way, which is less weight efficient, with respect to strength, than stretching-dominated behavior, such as in regular braced frameworks. Cancellous bone and other natural cellular solids have an optimized architecture. Their basic material is structured hierarchically and consists of nanometer-size elements, providing a benefit from size effects in the material strength. Designing cellular materials with a specific microarchitecture would allow one to exploit the structural advantages of stretching-dominated constructions as well as size-dependent strengthening effects. In this paper, we demonstrate that such materials may be fabricated. Applying 3D laser lithography, we produced and characterized micro-truss and -shell structures made from alumina-polymer composite. Size-dependent strengthening of alumina shells has been observed, particularly when applied with a characteristic thickness below 100 nm. The presented artificial cellular materials reach compressive strengths up to 280 MPa with densities well below 1,000 kg/m(3).

Disorder-driven topological phase transition in B i 2 S e 3 films

DOE PAGES

Brahlek, Matthew; Koirala, Nikesh; Salehi, Maryam; ...

2016-10-03

Topological insulators (TI) are a phase of matter that host unusual metallic states on their surfaces. Unlike the states that exist on the surface of conventional materials, these so-called topological surfaces states (TSS) are protected against disorder-related localization effects by time reversal symmetry through strong spin-orbit coupling. By combining transport measurements, angle-resolved photo-emission spectroscopy and scanning tunneling microscopy, we show that there exists a critical level of disorder beyond which the TI Bi 2Se 3 loses its ability to protect the metallic TSS and transitions to a fully insulating state. The absence of the metallic surface channels dictates that theremore » is a change in material’s topological character, implying that disorder can lead to a topological phase transition even without breaking the time reversal symmetry. This observation challenges the conventional notion of topologically-protected surface states, and will provoke new studies as to the fundamental nature of topological phase of matter in the presence of disorder.« less

3.3 CM JVLA Observations of Transitional Disks: Searching for Centimeter Pebbles

NASA Astrophysics Data System (ADS)

Zapata, Luis A.; Rodríguez, Luis F.; Palau, Aina

2017-01-01

We present sensitive (rms-noises ˜4-25 μJy) and high angular resolution (˜1″-2″) 8.9 GHz (3.3 cm) Karl G. Jansky Very Large Array radio continuum observations of 10 presumed transitional disks associated with young low-mass stars. We report the detection of radio continuum emission in 5 out of the 10 objects (RXJ1615, UX Tau A, LkCa15, RXJ1633, and SR 24s). In the case of LkCa15, the centimeter emission is extended, and has a similar morphology to that of the transitional disk observed at millimeter wavelengths with an inner depression. For these five detections, we construct the spectral energy distributions from the centimeter to submillimeter wavelengths, and find that they can be well fitted with a single (RXJ1633 and UX Tau A) or a two-component power law (LkCa15, RXJ1615, and SR 24s). For the cases where a single power law fits the data well, the centimeter emission is likely produced by optically thin dust with large grains (I.e., centimeter-size pebbles) present in the transitional disks. For the cases where a double power law fits the data, the centimeter emission might be produced by the combination of photoevaporation and a free-free jet. We conclude that RXJ1633 and UX Tau A are excellent examples of transitional disks where the structure of the emission from centimeter/millimeter pebbles can be studied. In the other cases, some other physical emitting mechanisms are also important in the centimeter regime.

The multiuniverse transition in superfluid 3He

NASA Astrophysics Data System (ADS)

Bunkov, Yury

2013-10-01

The symmetry-breaking phase transitions of the universe and of superfluid 3He may lead to the formation of different states with different order parameters. In both cases the energy potential below the transition temperature has a complicated multidimensional profile with many local minima and saddle points, which correspond to different states. Consequently, not only topological defects, but also islands of different metastable states can be created. Using 3He we can analyse the properties and experimental consequences of such transitions and, in particular, the first-order phase transition between the two low symmetry states.

The multiuniverse transition in superfluid 3He.

PubMed

Bunkov, Yury

2013-10-09

The symmetry-breaking phase transitions of the universe and of superfluid (3)He may lead to the formation of different states with different order parameters. In both cases the energy potential below the transition temperature has a complicated multidimensional profile with many local minima and saddle points, which correspond to different states. Consequently, not only topological defects, but also islands of different metastable states can be created. Using (3)He we can analyse the properties and experimental consequences of such transitions and, in particular, the first-order phase transition between the two low symmetry states.

Phase transition in the spin- 3 / 2 Blume-Emery-Griffiths model with antiferromagnetic second neighbor interactions

NASA Astrophysics Data System (ADS)

Yezli, M.; Bekhechi, S.; Hontinfinde, F.; EZ-Zahraouy, H.

2016-04-01

Two nonperturbative methods such as Monte-Carlo simulation (MC) and Transfer-Matrix Finite-Size-Scaling calculations (TMFSS) have been used to study the phase transition of the spin- 3 / 2 ​Blume-Emery-Griffiths model (BEG) with quadrupolar and antiferromagnetic next-nearest-neighbor exchange interactions. Ground state and finite temperature phase diagrams are obtained by means of these two methods. New degenerate phases are found and only second order phase transitions occur for all values of the parameter interactions. No sign of the intermediate phase is found from both methods. Critical exponents are also obtained from TMFSS calculations. Ising criticality and nonuniversal behaviors are observed depending on the strength of the second neighbor interaction.

Transition dipole-moment of the ν1 +ν3 band of acetylene measured with dual-comb Fourier-transform spectroscopy

NASA Astrophysics Data System (ADS)

Okubo, Sho; Iwakuni, Kana; Yamada, Koichi M. T.; Inaba, Hajime; Onae, Atsushi; Hong, Feng-Lei; Sasada, Hiroyuki

2017-11-01

The ν1 +ν3 vibration band of acetylene (C2H2) in the near infrared region was recorded with a dual-comb Fourier-transform spectrometer. We observed 56 transitions from P (26) to R (29) at six different column densities. The integral line intensity was determined for each recorded absorption line by fitting the line profile to Lambert-Beer's law with a Voigt function. Thanks to the outstanding capability of dual-comb spectroscopy to cover a broad spectrum in a relatively short time with high resolution and high frequency precision, we determined the reliable line strength for each ro-vibrational transition as well as the transition dipole moment for this band.

Renormalization of optical transition strengths in semiconductor nanoparticles due to band mixing

DOE PAGES

Velizhanin, Kirill A.

2016-05-25

We report that unique optical properties of semiconductor nanoparticles (SN) make them very promising in the multitude of applications including lasing, light emission and photovoltaics. In many of these applications it is imperative to understand the physics of interaction of electrons in a SN with external electromagnetic fields on the quantitative level. In particular, the strength of electron–photon coupling determines such important SN parameters as the radiative lifetime and absorption cross section. This strength is often assumed to be fully encoded by the so called Kane momentum matrix element. This parameter, however, pertains to a bulk semiconductor material and, asmore » such, is not sensitive to the quantum confinement effects in SNs. In this work we demonstrate that the quantum confinement, via the so called band mixing, can result in a significant suppression of the strength of electron interaction with electromagnetic field. Within the envelope function formalism we show how this suppression can be described by introducing an effective energy-dependent Kane momentum. Then, the effect of band mixing on the efficiencies of various photoinduced processes can be fully captured by the conventional formulae (e.g., spontaneous emission rate), once the conventional Kane momentum is substituted with the renormalized energy-dependent Kane momentum introduced in here. Lastly, as an example, we evaluate the energy-dependent Kane momentum for spherical PbSe and PbS SNs (i.e., quantum dots) and show that neglecting band mixing in these systems can result in the overestimation of absorption cross sections and emission rates by a factor of ~2.« less

Enhanced E3 Excitations in 144,146Ba and the Evolution of Octupole Collectivity

NASA Astrophysics Data System (ADS)

Bucher, B.; Zhu, S.; ANL, LLNL, LBNL, INL, UAM, Rochester, Maryland Collaboration

2017-09-01

Recent Coulomb excitation studies on 144,146Ba using the GRETINA-CHICO2 detection system with post-accelerated CARIBU beams have confirmed the existence of enhanced E3 transitions in these isotopes which are centered in a region that has long been predicted to exhibit stable octupole-deformed shapes. Furthermore, the widely-varying E1 strength observed between these isotopes is well-accounted for by models having octupole-deformed potentials, and the variation has been linked to increased occupancies of specific single-particle orbitals in the reflection-asymmetric potential. This talk will summarize the most recent experimental and theoretical results. In addition, data on octupole-related properties in the surrounding isotopes will be discussed in an attempt to better understand the origin and evolution of octupole collectivity in this mass region. This work is supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357 (ANL), DE-AC02-05CH11231 (LBNL, GRETINA), DOE DE-AC52-07NA27344 (LLNL), DE-AC07-05ID14517 (INL), and MINECO (Spain).

3D Rheological Modeling of NW Intraplate Europe, Deciphering Spatial Integrated strength patterns, Mechanical Strong Layering and EET

NASA Astrophysics Data System (ADS)

Beekman, F.; Hardebol, N.; Cloetingh, S.; Tesauro, M.

2006-12-01

Better understanding of 3D rheological heterogeneity of the European Lithosphere provide the key to tie the recorded intraplate deformation pattern to stress fields transmitted into plate interior from plate boundary forces. The first order strain patterns result from stresses transmitted through the European lithosphere that is marked by a patchwork of high strength variability from inherited structural and compositional heterogeneities and upper mantle thermal perturbations. As the lithospheric rheology depends primarily on its spatial structure, composition and thermal estate, the 3D strength model for the European lithosphere relies on a 3D compositional model that yields the compositional heterogeneities and an iteratively calculated thermal cube using Fouriers law for heat conduction. The accurate appraisal of spatial strength variability results from proper mapping and integration of the geophysical compositional and thermal input parameters. Therefore, much attention has been paid to a proper description of first order structural and tectonic features that facilitate compilation of the compositional and thermal input models. As such, the 3D strength model reflects the thermo-mechanical structure inherited from the Europeans polyphase deformation history. Major 3D spatial mechanical strength variability has been revealed. The East-European and Fennoscandian Craton to the NE exhibit high strength (30-50 1012 N/m) from low mantle temperatures and surface heatflow of 35-60 mW/m2 while central and western Europe reflect a polyphase Phanerozoic thermo- tectonic history. Here, regions with high rigidity are formed primarily by patches of thermally stabilized Variscan Massifs (e.g. Rhenish, Armorican, Bohemian, and Iberian Massif) with low heatflow and lithospheric thickness values (50-65 mW/m2; 110-150 km) yielding strengths of ~15-25 1012 N/m. In contrast, major axis of weakened lithosphere coincides with Cenozoic Rift System (e.g. Upper and Lower Rhine Grabens

Doubly magic Pb 208 : High-spin states, isomers, and E 3 collectivity in the yrast decay

DOE PAGES

Broda, R.; Janssens, R. V. F.; Iskra, Ł. W.; ...

2017-06-12

Yrast and near-yrast levels up to spin values in excess of I = 30h have been delineated in the doubly-magic 208Pb nucleus following deep-inelastic reactions involving 208Pb targets and, mostly, 430-MeV 48Ca and 1440-MeV 208Pb beams. The level scheme was established up to an excitation energy of 16.4 MeV, based on multi-fold γ-ray coincidence relationships measured with the Gammasphere array. Below the well-known, 0.5-μs 10 + isomer, ten new transitions were added to earlier work. The delineation of the higher parts of the level sequence benefited from analyses involving a number of prompt- and delayed-coincidence conditions. Three new isomeric statesmore » were established along the yrast line with I π = 20 - (10342 keV), 23 + (11361 keV), and 28 - (13675 keV), and respective half-lives of 22(3), 12.7(2), and 60(6) ns. Gamma transitions were also identified preceding in time the 28 - isomer, however, only a few could be placed in the level scheme and no firm spin-parity quantum numbers could be proposed. In contrast, for most states below this 28 - isomer, firm spin-parity values were assigned, based on total electron-conversion coefficients, deduced for low-energy (<500 keV) transitions from γ-intensity balances, and on measured γ-ray angular distributions. The latter also enabled the quantitative determination of mixing ratios. The transition probabilities extracted for all isomeric transitions in 208Pb have been reviewed and discussed in terms of the intrinsic structure of the initial and final levels involved. Particular emphasis was placed on the many observed E3 transitions as they often exhibit significant enhancements in strength (of the order of tens of W.u.) comparable to the one seen for the neutron j 15/2→g 9/2 E3 transition in 209Pb. In this context, the enhancement of the 725-keV E3 transition (56 W.u.) associated with the decay of the highest-lying 28 - isomer observed in this work remains particularly challenging to explain. Large

Search for weak M 1 transitions in 48Ca with inelastic proton scattering

NASA Astrophysics Data System (ADS)

Mathy, M.; Birkhan, J.; Matsubara, H.; von Neumann-Cosel, P.; Pietralla, N.; Ponomarev, V. Yu.; Richter, A.; Tamii, A.

2017-05-01

Background: The quenching of spin-isospin modes in nuclei is an important field of research in nuclear structure. It has an impact on astrophysical reaction rates and on fundamental processes like neutrinoless double-β decay. Gamow-Teller (GT) and spin-flip M 1 strengths are quenched. Concerning the latter, the Jπ=1+ resonance in the doubly magic nucleus 48Ca, dominated by a single transition, serves as a reference case. Purpose: The aim of the present work is to search for weak M 1 transitions in 48Ca with a high-resolution (p ,p') experiment at 295 MeV and forward angles including 0∘ and a comparison with results from a similar study using backward-angle electron scattering at low momentum transfers in order to estimate their contribution to the total B (M 1 ) strength in 48Ca. Methods: The spin-M 1 cross sections of individual peaks in the spectra are deduced with a multipole decomposition analysis (MDA) and converted to reduced spin-M 1 transition strengths by using the unit cross-section method. For a comparison with electron-scattering results, corresponding reduced B (M 1 ) transition strengths are extracted following the approach outlined in Birkhan et al. [Phys. Rev. C 93, 041302(R) (2016), 10.1103/PhysRevC.93.041302]. Results: In total, 30 peaks containing a M 1 contribution are found in the excitation energy region 7-13 MeV. The resulting B (M 1 ) strength distribution compares well to the electron-scattering results considering different factors limiting the sensitivity in both experiments and the enhanced importance of mechanisms breaking the proportionality of nuclear cross sections and electromagnetic matrix elements for weak transitions as studied here. The total strength of 1.14(7) μN2 deduced assuming a nonquenched isoscalar part of the (p ,p') cross sections agrees with the (e ,e') result of 1.21(13) μN2. A bin-wise analysis above 10 MeV provides an upper limit of 1.51(17) μN2. Conclusions: The present results confirm the previous electron

Ab initio computation of the transition temperature of the charge density wave transition in TiS e2

NASA Astrophysics Data System (ADS)

Duong, Dinh Loc; Burghard, Marko; Schön, J. Christian

2015-12-01

We present a density functional perturbation theory approach to estimate the transition temperature of the charge density wave transition of TiS e2 . The softening of the phonon mode at the L point where in TiS e2 a giant Kohn anomaly occurs, and the energy difference between the normal and distorted phase are analyzed. Both features are studied as functions of the electronic temperature, which corresponds to the Fermi-Dirac distribution smearing value in the calculation. The transition temperature is found to be 500 and 600 K by phonon and energy analysis, respectively, in reasonable agreement with the experimental value of 200 K.

Collision strengths for FIR and UV transtions in P III and the phosphorus abundance

NASA Astrophysics Data System (ADS)

Naghma, Rahla; Nahar, Sultana N.; Pradhan, Anil K.

2018-06-01

Phosphorus abundance is crucial for DNA-based extraterrestrial life in exoplanets. Atomic data for observed spectral lines of P-ions are needed for its accurate determination. We present the first calculations for collision strengths for the forbidden [P III] fine structure transition 3s^23p (^2P^o_{1/2-3/2}) within the ground state at 17.9 μm , as well as allowed UV transitions in the 3s^23p (^2P^o_{1/2,3/2}) \\rArr 3s3p^2 (^2D_{3/2,5/2}, ^2S_{1/2}, ^2P_{1/2,3/2}) multiplets between 915-1345 Å. Collision strengths are computed using the Breit-Pauli R-Matrix method including the first 18 levels, and they exhibit extensive auto-ionizing resonance structures. In particular, the Maxwellian averaged effective collision strength for the FIR 17.9 μm transition shows a factor 3 temperature variation broadly peaking at typical nebular temperatures. Its theoretical emissivity with solar phosphorus abundance is computed relative to Hβ and found to be similar to observed intensties from planetary nebulae; the abundances derived in earlier works are 3-5 times sub-solar. The results pertain to the reported paucity of phosphorus from preferred production sites in supernovae, and abundances in planetary nebulae and supernova remnants.

3.3 CM JVLA OBSERVATIONS OF TRANSITIONAL DISKS: SEARCHING FOR CENTIMETER PEBBLES

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

Zapata, Luis A.; Rodríguez, Luis F.; Palau, Aina, E-mail: lzapata@crya.unam.mx

We present sensitive (rms-noises ∼4–25 μ Jy) and high angular resolution (∼1″–2″) 8.9 GHz (3.3 cm) Karl G. Jansky Very Large Array radio continuum observations of 10 presumed transitional disks associated with young low-mass stars. We report the detection of radio continuum emission in 5 out of the 10 objects (RXJ1615, UX Tau A, LkCa15, RXJ1633, and SR 24s). In the case of LkCa15, the centimeter emission is extended, and has a similar morphology to that of the transitional disk observed at millimeter wavelengths with an inner depression. For these five detections, we construct the spectral energy distributions from themore » centimeter to submillimeter wavelengths, and find that they can be well fitted with a single (RXJ1633 and UX Tau A) or a two-component power law (LkCa15, RXJ1615, and SR 24s). For the cases where a single power law fits the data well, the centimeter emission is likely produced by optically thin dust with large grains (i.e., centimeter-size pebbles) present in the transitional disks. For the cases where a double power law fits the data, the centimeter emission might be produced by the combination of photoevaporation and a free–free jet. We conclude that RXJ1633 and UX Tau A are excellent examples of transitional disks where the structure of the emission from centimeter/millimeter pebbles can be studied. In the other cases, some other physical emitting mechanisms are also important in the centimeter regime.« less

Giant elastic tunability in strained BiFeO 3 near an electrically induced phase transition

DOE PAGES

Yu, Pu; Vasudevan, Rama K.; Tselev, Alexander; ...

2015-11-24

Elastic anomalies are signatures of phase transitions in condensed matters and have traditionally been studied using various techniques spanning from neutron scattering to static mechanical testing. Here, using band-excitation elastic/piezoresponse spectroscopy, we probed sub-MHz elastic dynamics of a tip bias-induced rhombohedral–tetragonal phase transition of strained (001)-BiFeO 3 (rhombohedral) ferroelectric thin films from ~10 3 nm 3 sample volumes. Near this transition, we observed that the Young's modulus intrinsically softens by over 30% coinciding with 2-3 folds enhancement of local piezoresponse. Coupled with phase-field modeling, we also addressed the influence of polarization switching and mesoscopic structural heterogeneities (e.g., domain walls) onmore » the kinetics of this phase transition, thereby providing fresh insights into the morphotropic phase boundary (MPB) in ferroelectrics. Moreover, the giant electrically tunable elastic stiffness and corresponding electromechanical properties observed here suggest potential applications of BiFeO 3 in next-generation frequency-agile electroacoustic devices, based on utilization of the soft modes underlying successive ferroelectric phase transitions.« less

Structural properties of Sb 2S 3 under pressure: Evidence of an electronic topological transition

DOE PAGES

Efthimiopoulos, Ilias; Buchan, Cienna; Wang, Yuejian

2016-04-06

High-pressure Raman spectroscopy and x-ray diffraction of Sb 2S 3 up to 53 GPa reveals two phase transitions at 5 GPa and 15 GPa. The first transition is evidenced by noticeable compressibility changes in distinct Raman-active modes, in the lattice parameter axial ratios, the unit cell volume, as well as in specific interatomic bond lengths and bond angles. By taking into account relevant results from the literature, we assign these effects to a second-order isostructural transition arising from an electronic topological transition in Sb 2S 3 near 5 GPa. Close comparison between Sb 2S 3 and Sb 2S 3 upmore » to 10 GPa reveals a slightly diverse structural behavior for these two compounds after the isostructural transition pressure. This structural diversity appears to account for the different pressure-induced electronic behavior of Sb 2S 3 and Sb 2S 3 up to 10 GPa, i.e. the absence of an insulator-metal transition in Sb 2S 3 up to that pressure. Lastly, the second high-pressure modification appearing above 15 GPa appears to trigger a structural disorder at ~20 GPa; full decompression from 53 GPa leads to the recovery of an amorphous state.« less

Lifshitz transition with interactions in high magnetic fields: Application to CeIn3

NASA Astrophysics Data System (ADS)

Schlottmann, Pedro

2012-02-01

The N'eel ordered state of CeIn3 is suppressed by a magnetic field of 61 T at ambient pressure. There is a second transition at ˜45 T, which has been associated with a Lifshitz transition [1,2]. Skin depth measurements [2] indicate that the transition is discontinuous as T ->0. Motivated by this transition we study the effects of Landau quantization and interaction among carriers on a Lifshitz transition. The Landau quantization leads to quasi-one-dimensional behavior for the direction parallel to the field. Repulsive Coulomb interactions give rise to a gas of strongly coupled carriers [3]. The density correlation function is calculated for a special long-ranged potential [4]. It is concluded that in CeIn3 a pocket is being emptied as a function of field in a discontinuous fashion in the ground state. This discontinuity is gradually smeared by the temperature [4] in agreement with the skin depth experiments [2]. 0.05in [1] S.E. Sebastian et al, PNAS 106, 7741 (2009). [2] K.M. Purcell et al, Phys. Rev. B 79, 214428 (2009). [3] P. Schlottmann and R. Gerhardts, Z. Phys. B 34, 363 (1979). [4] P. Schlottmann, Phys. Rev. B 83, 115133 (2011); J. Appl. Phys., in print.

Novel Electronic Behavior Driving NdNiO 3 Metal-Insulator Transition

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

Upton, M. H.; Choi, Yongseong; Park, Hyowon

2015-07-01

We present evidence that the metal-insulator transition (MIT) in a tensile-strained NdNiO3 (NNO) film is facilitated by a redistribution of electronic density and that it neither requires Ni charge disproportionation nor a symmetry change [U. Staub et al., Phys. Rev. Lett. 88, 126402 (2002); R. Jaramillo et al., Nat. Phys. 10, 304 (2014)]. Given that epitaxial tensile strain in thin NNO films induces preferential occupancy of the e(g) d(x2-y2) orbital we propose that the larger transfer integral of this orbital state with the O 2p orbital state mediates a redistribution of electronic density from the Ni atom. A decrease inmore » the Ni d(x2-y2) orbital occupation is directly observed by resonant inelastic x-ray scattering below the MIT temperature. Furthermore, an increase in the Nd charge occupancy is measured by x-ray absorption at the Nd L-3 edge. Both spin-orbit coupling and crystal field effects combine to break the degeneracy of the Nd 5d states, shifting the energy of the Nd e(g) d(x2-y2) orbit towards the Fermi level, allowing the A site to become an active acceptor during the MIT. This work identifies the relocation of electrons from the Ni 3d to the Nd 5d orbitals across the MIT. We propose that the insulating gap opens between the Ni 3d and O 2p states, resulting from Ni 3d electron localization. The transition seems to be neither a purely Mott-Hubbard transition nor a simple charge transfer.« less

Study of photon strength functions via (γ→, γ', γ″) reactions at the γ3-setup

NASA Astrophysics Data System (ADS)

Isaak, Johann; Savran, Deniz; Beck, Tobias; Gayer, Udo; Krishichayan; Löher, Bastian; Pietralla, Norbert; Scheck, Marcus; Tornow, Werner; Werner, Volker; Zilges, Andreas

2018-05-01

One of the basic ingredients for the modelling of the nucleosynthesis of heavy elements are so-called photon strength functions and the assumption of the Brink-Axel hypothesis. This hypothesis has been studied for many years by numerous experiments using different and complementary reactions. The present manuscript aims to introduce a model-independent approach to study photon strength functions via γ-γ coincidence spectroscopy of photoexcited states in 128Te. The experimental results provide evidence that the photon strength function extracted from photoabsorption cross sections is not in an overall agreement with the one determined from direct transitions to low-lying excited states.

ScienceToGo.org: The Strengths and Weaknesses of Communicating Climate Change through Mass Transit Advertising Spaces

NASA Astrophysics Data System (ADS)

Lustick, D. S.; Lohmeier, J.; Chen, R. F.; Wilson, R.; Rabkin, D.; Thompson, S. R.

2016-02-01

Engaging urban populations with climate change science is a difficult challenge since cities can seem so removed from the `natural environment.' However, mass transit provides an inherent means of communicating environmental messages with a cross section of the urban population. The Out of Home Media (OHM) spaces found on platforms and inside train cars provide a potentially effective means of bringing informal science learning opportunities directly to an underserved STEM audience. Our team felt that any messaging curriculum for a coastal urban subway system must complement the scary reality of the impacts of a changing climate (i.e. rising sea levels) with current examples of how the city is preparing for a more sustainable future. Urban areas such as Boston must develop adaptation and mitigation strategies that will help them not only survive, but thrive in a changing environment. In 2013-14, ScienceToGo.org ran a series of 12 engaging posters and placards staring `Ozzie the Ostrich' on the Massachusetts Bay Transit Authority's Red and Orange subway lines targeting an audience of more than 400,000 riders per day. The 12 month curriculum was divided into three phases: reality, relevance, and hope. During the presentation, we will present the results of our quasi-experimental research which identifies, quantifies, and explains the observed impacts of the campaign on adult riders. The strengths and weaknesses of the communication strategy will be discussed. Finally, we will conclude with some recommendations for how this work could improve and inform other urban informal science learning initiatives.

Suppression of spin-state transition in epitaxially strained LaCoO3

NASA Astrophysics Data System (ADS)

Pinta, C.; Fuchs, D.; Merz, M.; Wissinger, M.; Arac, E.; v. Löhneysen, H.; Samartsev, A.; Nagel, P.; Schuppler, S.

2008-11-01

Epitaxial thin films of LaCoO3 (e-LCO) exhibit ferromagnetic order with a transition temperature TC=85K while polycrystalline thin LaCoO3 films (p-LCO) remain paramagnetic. The temperature-dependent spin-state structure for both e-LCO and p-LCO was studied by x-ray absorption spectroscopy at the CoL2,3 and OK edges. Considerable spectral redistributions over temperature are observed for p-LCO . The spectra for e-LCO , on the other hand, do not show any significant changes for temperatures between 30 and 450 K at both edges, indicating that the spin state remains constant and that the epitaxial strain inhibits any population of the low-spin (S=0) state with decreasing temperature. This observation identifies an important prerequisite for ferromagnetism in e-LCO thin films.

E-H heating mode transition in inductive discharges with different antenna sizes

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

Lee, Hyo-Chang, E-mail: flower4507@hanyang.ac.kr; Chung, Chin-Wook, E-mail: joykang@hanyang.ac.kr

The spatial distribution of plasma density and the transition power for capacitive (E) to inductive (H) mode transition are studied in planar type inductively coupled plasmas with different antenna sizes. The spatial plasma distribution has a relatively flat profile at a low gas pressure, while the plasma profile is affected by the antenna size at higher gas pressure. The transition power for the E to H mode transition is shown to be critically affected by the antenna size. When the discharge is sustained by a small one-turn antenna coil, the transition power has a minimum value at Ar gas ofmore » 20 mTorr. However, the minimum transition power is shown at a relatively high gas pressure (40–60 mTorr) in the case of a large one-turn antenna coil. This change in the transition power can be understood by the thermal transport of the energetic electrons with non-local kinetics to the chamber wall. This non-local kinetic effect indicates that the transition power can also increase even for a small antenna if the antenna is placed near the wall.« less

Dual-Comb Spectroscopy of the ν_1+ ν_3 Band of Acetylene: Intensity and Transition Dipole Moment

NASA Astrophysics Data System (ADS)

Iwakuni, Kana; Okubo, Sho; Yamada, Koichi MT; Inaba, Hajime; Onae, Atsushi; Hong, Feng-Lei; Sasada, Hiroyuki

2017-06-01

The ν_1+ν_3 vibration band of ^{12}C_2H_2 is recorded with a homemade dual-comb spectrometer. The spectral resolution and the accuracy of frequency determination are high, and the bandwidth is broad enough to take spectrum of the whole band in one shot. The last remarkable competence enables us to record all the spectral lines under constant experimental conditions. The linewidth and line strength of the P(26) to R(29) transitions are determined by fitting the line profile to Lambert-Beer's law with a Voigt function. In the course of analysis, we found the ortho-para dependence of the pressure-broadening coefficient. This time, we have determined the transition dipole moment of the ν_1+ν_3 band. It is noted that the transition dipole moment determined from the ortho lines agrees with that from the para lines. S. Okubo et al., Applied Physics Express 8, 082402 (2015). K.Iwakuni et al., 71th ISMS, WK15 K. Iwakuni et al., Physical Review Letters 117, 143902 (2016).

Non-equilibrium quantum phase transition via entanglement decoherence dynamics.

PubMed

Lin, Yu-Chen; Yang, Pei-Yun; Zhang, Wei-Min

2016-10-07

We investigate the decoherence dynamics of continuous variable entanglement as the system-environment coupling strength varies from the weak-coupling to the strong-coupling regimes. Due to the existence of localized modes in the strong-coupling regime, the system cannot approach equilibrium with its environment, which induces a nonequilibrium quantum phase transition. We analytically solve the entanglement decoherence dynamics for an arbitrary spectral density. The nonequilibrium quantum phase transition is demonstrated as the system-environment coupling strength varies for all the Ohmic-type spectral densities. The 3-D entanglement quantum phase diagram is obtained.

Energy levels, radiative rates and electron impact excitation rates for transitions in He-like Ga XXX, Ge XXXI, As XXXII, Se XXXIII and Br XXXIV

NASA Astrophysics Data System (ADS)

Aggarwal, Kanti M.; Keenan, Francis P.

2013-04-01

We report calculations of energy levels, radiative rates and electron impact excitation cross sections and rates for transitions in He-like Ga XXX, Ge XXXI, As XXXII, Se XXXIII and Br XXXIV. The grasp (general-purpose relativistic atomic structure package) is adopted for calculating energy levels and radiative rates. For determining the collision strengths, and subsequently the excitation rates, the Dirac atomic R-matrix code (darc) is used. Oscillator strengths, radiative rates and line strengths are reported for all E1, E2, M1 and M2 transitions among the lowest 49 levels of each ion. Additionally, theoretical lifetimes are provided for all 49 levels of the above five ions. Collision strengths are averaged over a Maxwellian velocity distribution and the effective collision strengths obtained listed over a wide temperature range up to 108 K. Comparisons are made with similar data obtained using the flexible atomic code (fac) to highlight the importance of resonances, included in calculations with darc, in the determination of effective collision strengths. Discrepancies between the collision strengths from darc and fac, particularly for some forbidden transitions, are also discussed. Finally, discrepancies between the present results for effective collision strengths with the darc code and earlier semi-relativistic R-matrix data are noted over a wide range of electron temperatures for many transitions in all ions.

Accurate Calculation of Oscillator Strengths for CI II Lines Using Non-orthogonal Wavefunctions

NASA Technical Reports Server (NTRS)

Tayal, S. S.

2004-01-01

Non-orthogonal orbitals technique in the multiconfiguration Hartree-Fock approach is used to calculate oscillator strengths and transition probabilities for allowed and intercombination lines in Cl II. The relativistic corrections are included through the Breit-Pauli Hamiltonian. The Cl II wave functions show strong term dependence. The non-orthogonal orbitals are used to describe the term dependence of radial functions. Large sets of spectroscopic and correlation functions are chosen to describe adequately strong interactions in the 3s(sup 2)3p(sup 3)nl (sup 3)Po, (sup 1)Po and (sup 3)Do Rydberg series and to properly account for the important correlation and relaxation effects. The length and velocity forms of oscillator strength show good agreement for most transitions. The calculated radiative lifetime for the 3s3p(sup 5) (sup 3)Po state is in good agreement with experiment.

Enhanced low-energy γ -decay strength of 70Ni and its robustness within the shell model

NASA Astrophysics Data System (ADS)

Larsen, A. C.; Midtbø, J. E.; Guttormsen, M.; Renstrøm, T.; Liddick, S. N.; Spyrou, A.; Karampagia, S.; Brown, B. A.; Achakovskiy, O.; Kamerdzhiev, S.; Bleuel, D. L.; Couture, A.; Campo, L. Crespo; Crider, B. P.; Dombos, A. C.; Lewis, R.; Mosby, S.; Naqvi, F.; Perdikakis, G.; Prokop, C. J.; Quinn, S. J.; Siem, S.

2018-05-01

Neutron-capture reactions on very neutron-rich nuclei are essential for heavy-element nucleosynthesis through the rapid neutron-capture process, now shown to take place in neutron-star merger events. For these exotic nuclei, radiative neutron capture is extremely sensitive to their γ -emission probability at very low γ energies. In this work, we present measurements of the γ -decay strength of 70Ni over the wide range 1.3 ≤Eγ≤8 MeV. A significant enhancement is found in the γ -decay strength for transitions with Eγ<3 MeV. At present, this is the most neutron-rich nucleus displaying this feature, proving that this phenomenon is not restricted to stable nuclei. We have performed E 1 -strength calculations within the quasiparticle time-blocking approximation, which describe our data above Eγ≃5 MeV very well. Moreover, large-scale shell-model calculations indicate an M 1 nature of the low-energy γ strength. This turns out to be remarkably robust with respect to the choice of interaction, truncation, and model space, and we predict its presence in the whole isotopic chain, in particular the neutron-rich Ni 72 ,74 ,76 .

Electric dipole transitions for four-times ionized cerium (Ce V)

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

Usta, Betül Karaçoban, E-mail: bkaracoban@sakarya.edu.tr; Akgün, Elif, E-mail: elif.akgun@ogr.sakarya.edu.tr; Alparslan, Büşra, E-mail: busra.alparslan1@ogr.sakarya.edu.tr

2016-03-25

We have calculated the transition parameters, such as wavelengths, oscillator strengths, and transition probabilities (or rates), for the electric dipole (E1) transitions in four-times ionized cerium (Ce V, Z = 58) by using the multiconfiguration Hartree-Fock method within the framework of Breit-Pauli (MCHF+BP) relativistic corrections and the relativistic Hartree-Fock (HFR) method. The obtained results have been compared with other works available in literature. A discussion of these calculations for Ce V in this study has also been in view of the MCHF+BP and HFR methods.

Multiconfiguration Dirac-Hartree-Fock energy levels, oscillator strengths, transition probabilities, hyperfine constants and Landé g-factor of intermediate Rydberg series in neutral argon atom

NASA Astrophysics Data System (ADS)

Salah, Wa'el; Hassouneh, Ola

2017-04-01

We computed the energy levels, oscillator strengths f_{ij}, the radiative transition rates A_{ij}, the Landé g -factor, the magnetic dipole moment and the electric quadrupole hyperfine constants of the intermediate Rydberg series ns [k]J ( 4 ≤ n ≤ 6), nd [k]J (3 ≤ n ≤ 4), np [k]J (4 ≤ n ≤ 5) relative to the ground state 3p6 1S0 for neutral argon atom spectra. The values are obtained in the framework of the multiconfiguration Dirac-Hartree-Fock (MCDHF) approach. In this approach, Breit interaction, leading quantum electrodynamics (QED) effects and self-energy correction are taken into account. Moreover, these spectroscopic parameters have been calculated for many levels belonging to the configuration 3p54s, 3p55s, 3p56s, 3p53d, 3p54d, 3p54p, 3p55p as well as for transitions between levels 3p54s-3p54p, 3p54p-3p53d, 3p54p-3p55s, 3p55s-3p55p and 3p55p-3p56s. The large majority of the lines from the 4p-5s and 4p-3d, 5s-5p and 5p-6s transition arrays have been observed and the calculations are consistent with the J -file-sum rule. The obtained theoretical values are compared with previous experimental and theoretical data available in the literature. An overall satisfactory agreement is noticed allowing assessing the reliability of our data.

The realization of the dipole (γ, γ) method and its application to determine the absolute optical oscillator strengths of helium.

PubMed

Xu, Long-Quan; Liu, Ya-Wei; Kang, Xu; Ni, Dong-Dong; Yang, Ke; Hiraoka, Nozomu; Tsuei, Ku-Ding; Zhu, Lin-Fan

2015-12-17

The dipole (γ, γ) method, which is the inelastic x-ray scattering operated at a negligibly small momentum transfer, is proposed and realized to determine the absolute optical oscillator strengths of the vanlence-shell excitations of atoms and molecules. Compared with the conventionally used photoabsorption method, this new method is free from the line saturation effect, which can seriously limit the accuracies of the measured photoabsorption cross sections for discrete transitions with narrow natural linewidths. Furthermore, the Bethe-Born conversion factor of the dipole (γ, γ) method varies much more slowly with the excitation energy than does that of the dipole (e, e) method. Absolute optical oscillator strengths for the excitations of 1s(2) → 1 snp(n = 3-7) of atomic helium have been determined using the high-resolution dipole (γ, γ) method, and the excellent agreement of the present measurements with both those measured by the dipole (e, e) method and the previous theoretical calculations indicates that the dipole (γ, γ) method is a powerful tool to measure the absolute optical oscillator strengths of the valence-shell excitations of atoms and molecules.

Nanosecond lifetime measurements of Iπ=9/2- intrinsic excited states and low-lying B(E1) strengths in 183Re using combined HPGe-LaBr3 coincidence spectroscopy

NASA Astrophysics Data System (ADS)

Gurgi, L. A.; Regan, P. H.; Daniel, T.; Podolyák, Zs.; Bruce, A. M.; Mason, P. J. R.; Mǎrginean, N.; Mǎrginean, R.; Werner, V.; Alharbi, T.; Alkhomashi, N.; Bajoga, A. D.; Britton, R.; Cǎta-Danil, I.; Carroll, R. J.; Deleanu, D.; Bucurescu, D.; Florea, N.; Gheorghe, I.; Ghita, D. G.; Glodariu, T.; Lice, R.; Mihai, C.; Mulholland, K. F.; Negret, A.; Olacel, A.; Roberts, O. J.; Sava, T.; Söderström, P.-A.; Stroe, L.; Suvaila, R.; Toma, S.; Wilson, E.; Wood, R. T.

2017-08-01

This paper presents precision measurements of electromagnetic decay probabilities associated with electric dipole transitions in the prolate-deformed nucleus 183Re. The nucleus of interest was formed using the fusion evaporation reaction 180Hf(7Li,4n)183Re at a beam energy of 30 MeV at the tandem accelerator at the HH-IFIN Institute, Bucharest Romania. Coincident decay gamma rays from near-yrast cascades were detected using the combined HPGe-LaBr3 detector array ROSPHERE. The time differences between cascade gamma rays were measured using the LaBr3 detectors to determine the half-lives of the two lowest lying spin-parity 9/2- states at excitation energies of 496 and 617 keV to be 5.65(5) and 2.08(3) ns respectively. The deduced E1 transition rates from these two states are discussed in terms of the K-hindrance between the low-lying structures in this prolate-deformed nucleus.

Chairside CAD/CAM materials. Part 2: Flexural strength testing.

PubMed

Wendler, Michael; Belli, Renan; Petschelt, Anselm; Mevec, Daniel; Harrer, Walter; Lube, Tanja; Danzer, Robert; Lohbauer, Ulrich

2017-01-01

Strength is one of the preferred parameters used in dentistry for determining clinical indication of dental restoratives. However, small dimensions of CAD/CAM blocks limit reliable measurements with standardized uniaxial bending tests. The objective of this study was to introduce the ball-on-three-ball (B3B) biaxial strength test for dental for small CAD/CAM block in the context of the size effect on strength predicted by the Weibull theory. Eight representative chairside CAD/CAM materials ranging from polycrystalline zirconia (e.max ZirCAD, Ivoclar-Vivadent), reinforced glasses (Vitablocs Mark II, VITA; Empress CAD, Ivoclar-Vivadent) and glass-ceramics (e.max CAD, Ivoclar-Vivadent; Suprinity, VITA; Celtra Duo, Dentsply) to hybrid materials (Enamic, VITA; Lava Ultimate, 3M ESPE) have been selected. Specimens were prepared with highly polished surfaces in rectangular plate (12×12×1.2mm 3 ) or round disc (Ø=12mm, thickness=1.2mm) geometries. Specimens were tested using the B3B assembly and the biaxial strength was determined using calculations derived from finite element analyses of the respective stress fields. Size effects on strength were determined based on results from 4-point-bending specimens. A good agreement was found between the biaxial strength results for the different geometries (plates vs. discs) using the B3B test. Strength values ranged from 110.9MPa (Vitablocs Mark II) to 1303.21MPa (e.max ZirCAD). The strength dependency on specimen size was demonstrated through the calculated effective volume/surface. The B3B test has shown to be a reliable and simple method for determining the biaxial strength restorative materials supplied as small CAD/CAM blocks. A flexible solution was made available for the B3B test in the rectangular plate geometry. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Study of dipion transitions among Υ(3S), Υ(2S), and Υ(1S) states

NASA Astrophysics Data System (ADS)

Cronin-Hennessy, D.; Gao, K. Y.; Hietala, J.; Kubota, Y.; Klein, T.; Lang, B. W.; Poling, R.; Scott, A. W.; Smith, A.; Zweber, P.; Dobbs, S.; Metreveli, Z.; Seth, K. K.; Tomaradze, A.; Ernst, J.; Ecklund, K. M.; Severini, H.; Love, W.; Savinov, V.; Lopez, A.; Mehrabyan, S.; Mendez, H.; Ramirez, J.; Huang, G. S.; Miller, D. H.; Pavlunin, V.; Sanghi, B.; Shipsey, I. P. J.; Xin, B.; Adams, G. S.; Anderson, M.; Cummings, J. P.; Danko, I.; Hu, D.; Moziak, B.; Napolitano, J.; He, Q.; Insler, J.; Muramatsu, H.; Park, C. S.; Thorndike, E. H.; Yang, F.; Artuso, M.; Blusk, S.; Khalil, S.; Li, J.; Menaa, N.; Mountain, R.; Nisar, S.; Randrianarivony, K.; Sia, R.; Skwarnicki, T.; Stone, S.; Wang, J. C.; Bonvicini, G.; Cinabro, D.; Dubrovin, M.; Lincoln, A.; Pappas, S. P.; Weinstein, A. J.; Asner, D. M.; Edwards, K. W.; Naik, P.; Briere, R. A.; Ferguson, T.; Tatishvili, G.; Vogel, H.; Watkins, M. E.; Rosner, J. L.; Adam, N. E.; Alexander, J. P.; Cassel, D. G.; Duboscq, J. E.; Ehrlich, R.; Fields, L.; Galik, R. S.; Gibbons, L.; Gray, R.; Gray, S. W.; Hartill, D. L.; Heltsley, B. K.; Hertz, D.; Jones, C. D.; Kandaswamy, J.; Kreinick, D. L.; Kuznetsov, V. E.; Mahlke-Krüger, H.; Mohapatra, D.; Onyisi, P. U. E.; Patterson, J. R.; Peterson, D.; Pivarski, J.; Riley, D.; Ryd, A.; Sadoff, A. J.; Schwarthoff, H.; Shi, X.; Stroiney, S.; Sun, W. M.; Wilksen, T.; Athar, S. B.; Patel, R.; Yelton, J.; Rubin, P.; Cawlfield, C.; Eisenstein, B. I.; Karliner, I.; Kim, D.; Lowrey, N.; Selen, M.; White, E. J.; Wiss, J.; Mitchell, R. E.; Shepherd, M. R.; Besson, D.; Pedlar, T. K.

2007-10-01

We present measurements of decay matrix elements for hadronic transitions of the form Υ(nS)→Υ(mS)ππ, where (n,m)=(3,1),(2,1),(3,2). We reconstruct charged and neutral pion modes with the final state Upsilon decaying to either μ+μ- or e+e-. Dalitz plot distributions for the 12 decay modes are fit individually as well as jointly assuming isospin symmetry, thereby measuring the matrix elements of the decay amplitude. We observe and account for the anomaly previously noted in the dipion invariant mass distribution for the Υ(3S)→Υ(1S)ππ transition and obtain good descriptions of the dynamics of the decay using the most general decay amplitude allowed by partial conservation of the axial-vector current considerations. The fits further indicate that the Υ(2S)→Υ(1S)ππ and Υ(3S)→Υ(2S)ππ transitions also show the presence of terms in the decay amplitude that were previously ignored, although at a relatively suppressed level.

Neurotrophin NT3 promotes ovarian primordial to primary follicle transition

PubMed Central

Nilsson, Eric; Dole, Gretchen; Skinner, Michael K

2017-01-01

Neurotrophins are growth factors that are known to have a role in promoting cell survival and differentiation. The focus of the current study is to examine the role of neurotrophins in regulating ovarian primordial follicle development. Ovaries from 4-day old rats were placed into organ culture and cultured for 10 days in the absence or presence of neurotrophin-3 (NT3), brain-derived neurotrophic factor (BDNF), or nerve growth factor (NGF). Treatment of ovaries with NT3 resulted in a significant (P<0.01) increase in primordial follicle development (i.e. primordial to primary follicle transition). Treatment with BDNF at high doses of 100–250 ng/ml also significantly (P<0.01) increased primordial follicle development, but NGF had no effect. Immunohistochemical studies determined that NT3 was present in granulosa cells, interstitial tissue, and in the oocytes of primordial and primary follicles. The NT3 receptor NTRK3 was present in oocytes at all stages of development. Analysis of ovaries that contain predominantly primordial follicles demonstrated the transcripts for NT3, NTRK3, NGF, and the BDNF/neurotrophin-4 (NT4) receptor NTRK2 are expressed, while BDNF, NT4, and the NGF receptor NTRK1 are not detectable. Inhibition of the NTRK3 receptor with the tyrphostin AG 879 resulted in oocyte death and a significant (P<0.01) reduction in follicle pool size. Inhibition of the NTRK receptors with K252a slowed primordial to primary follicle transition. A microarray analysis demonstrated that a small number of genes were differentially expressed after NT3 treatment. Observations indicate that the neurotrophin NT3, acting through the NTRK3 receptor in oocytes, promotes the primordial to primary follicle transition. PMID:19584175

Application of the Zero-Order Reaction Rate Model and Transition State Theory to predict porous Ti6Al4V bending strength.

PubMed

Reig, L; Amigó, V; Busquets, D; Calero, J A; Ortiz, J L

2012-08-01

Porous Ti6Al4V samples were produced by microsphere sintering. The Zero-Order Reaction Rate Model and Transition State Theory were used to model the sintering process and to estimate the bending strength of the porous samples developed. The evolution of the surface area during the sintering process was used to obtain sintering parameters (sintering constant, activation energy, frequency factor, constant of activation and Gibbs energy of activation). These were then correlated with the bending strength in order to obtain a simple model with which to estimate the evolution of the bending strength of the samples when the sintering temperature and time are modified: σY=P+B·[lnT·t-ΔGa/R·T]. Although the sintering parameters were obtained only for the microsphere sizes analysed here, the strength of intermediate sizes could easily be estimated following this model. Copyright © 2012 Elsevier B.V. All rights reserved.

Non-equilibrium quantum phase transition via entanglement decoherence dynamics

PubMed Central

Lin, Yu-Chen; Yang, Pei-Yun; Zhang, Wei-Min

2016-01-01

We investigate the decoherence dynamics of continuous variable entanglement as the system-environment coupling strength varies from the weak-coupling to the strong-coupling regimes. Due to the existence of localized modes in the strong-coupling regime, the system cannot approach equilibrium with its environment, which induces a nonequilibrium quantum phase transition. We analytically solve the entanglement decoherence dynamics for an arbitrary spectral density. The nonequilibrium quantum phase transition is demonstrated as the system-environment coupling strength varies for all the Ohmic-type spectral densities. The 3-D entanglement quantum phase diagram is obtained. PMID:27713556

Muscular Strength and Power in 3-to 7-Year-Old Children.

PubMed

Fry, Andrew C; Irwin, Carol C; Nicoll, Justin X; Ferebee, David E

2015-08-01

To determine absolute and relative (adjusted for body mass) strength, mean power, and mean velocity for upper and lower body resistance exercises, forty-seven young boys and girls participated in maximal strength testing. Healthy young boys and girls, ages 3- to 7-years old, were tested for one-repetition maximum (1-RM) strength, and 70% of 1-RM to determine mean power and mean velocity on the chest press and leg press exercises. Adult weight machines were modified to accommodate the smaller size and lower strength levels of the children. A 2 × 4 (sex × age) ANOVA was used to determine age and sex differences in performance. No interaction or sex differences were observed for any variable at any age. 1-RM strength, mean power, and mean velocity significantly increased across ages (p ≤ .05). When adjusted for body mass, the changes were insignificant, with one exception. Relative mean power for the bench press increased with age. Data indicated children from 3-7 years of age are capable of performing strength and power tests, but may require more attempts at maximal loads compared with adults. It appears that muscular strength and velocity during this stage of development are primarily dependent on increasing body mass, whereas power is influenced by additional variable(s).

Effects of different strength training frequencies on maximum strength, body composition and functional capacity in healthy older individuals.

PubMed

Turpela, Mari; Häkkinen, Keijo; Haff, Guy Gregory; Walker, Simon

2017-11-01

There is controversy in the literature regarding the dose-response relationship of strength training in healthy older participants. The present study determined training frequency effects on maximum strength, muscle mass and functional capacity over 6months following an initial 3-month preparatory strength training period. One-hundred and six 64-75year old volunteers were randomly assigned to one of four groups; performing strength training one (EX1), two (EX2), or three (EX3) times per week and a non-training control (CON) group. Whole-body strength training was performed using 2-5 sets and 4-12 repetitions per exercise and 7-9 exercises per session. Before and after the intervention, maximum dynamic leg press (1-RM) and isometric knee extensor and plantarflexor strength, body composition and quadriceps cross-sectional area, as well as functional capacity (maximum 7.5m forward and backward walking speed, timed-up-and-go test, loaded 10-stair climb test) were measured. All experimental groups increased leg press 1-RM more than CON (EX1: 3±8%, EX2: 6±6%, EX3: 10±8%, CON: -3±6%, P<0.05) and EX3 improved more than EX1 (P=0.007) at month 9. Compared to CON, EX3 improved in backward walk (P=0.047) and EX1 in timed-up-and-go (P=0.029) tests. No significant changes occurred in body composition. The present study found no evidence that higher training frequency would induce greater benefit to maximum walking speed (i.e. functional capacity) despite a clear dose-response in dynamic 1-RM strength, at least when predominantly using machine weight-training. It appears that beneficial functional capacity improvements can be achieved through low frequency training (i.e. 1-2 times per week) in previously untrained healthy older participants. Copyright © 2017 Elsevier Inc. All rights reserved.

The ACTN3 R577X variant in sprint and strength performance

PubMed Central

Kim, Hyeoijin; Song, Keon-Hyoung; Kim, Chul-Hyun

2014-01-01

[Purpose] The aim of this study is to examine the association between the distribution of ACTN3 genotypes and alleles in power, speed, and strength-oriented athletics. [Methods] ACTN3 genotyping was carried out for a total of 975 Korean participants: top-level sprinters (n = 58), top-level strength athletes (n = 63), and healthy controls (n = 854). [Results] Genetic associations were evaluated by chi-squire test or Fisher’s exact test. In the power-oriented group composed of sprinters and strength athletes, the frequency of the XX genotype was significantly underrepresented (11.6%) in comparison to its representation in the control group (11.6% versus 19.1%, P < 0.05). When the power-oriented group was divided into strength-oriented and speed-oriented groups, no significant difference in the ACTN3 XX genotype was found between the strength-oriented athletes and the controls (15.9% versus 19.1%, P < 0.262). Only the speed-oriented athletes showed significant differences in the frequency distributions of the ACTN3 XX genotype (6.9% versus 19.1%, P < 0.05) from that of the controls. [Conclusion] The ACTN3 genotype seems to mainly affect sports performance and especially speed. PMID:25671201

The ACTN3 R577X variant in sprint and strength performance.

PubMed

Kim, Hyeoijin; Song, Keon-Hyoung; Kim, Chul-Hyun

2014-12-01

The aim of this study is to examine the association between the distribution of ACTN3 genotypes and alleles in power, speed, and strength-oriented athletics. ACTN3 genotyping was carried out for a total of 975 Korean participants: top-level sprinters (n = 58), top-level strength athletes (n = 63), and healthy controls (n = 854). Genetic associations were evaluated by chi-squire test or Fisher's exact test. In the power-oriented group composed of sprinters and strength athletes, the frequency of the XX genotype was significantly underrepresented (11.6%) in comparison to its representation in the control group (11.6% versus 19.1%, P < 0.05). When the power-oriented group was divided into strength-oriented and speed-oriented groups, no significant difference in the ACTN3 XX genotype was found between the strength-oriented athletes and the controls (15.9% versus 19.1%, P < 0.262). Only the speed-oriented athletes showed significant differences in the frequency distributions of the ACTN3 XX genotype (6.9% versus 19.1%, P < 0.05) from that of the controls. The ACTN3 genotype seems to mainly affect sports performance and especially speed.

Spectroscopic investigations of Nd3+ doped flouro- and chloro-borate glasses.

PubMed

Mohan, Shaweta; Thind, Kulwant Singh; Sharma, Gopi; Gerward, Leif

2008-10-01

Spectroscopic and physical properties of Nd3+ doped sodium lead flouro- and chloro-borate glasses of the type 20NaX-30PbO-49.5B2O3-0.5Nd2O3 (X=F and Cl) have been investigated. Optical absorption spectra have been used to determine the Slater Condon (F2, F4, and F6), spin orbit xi4f and Racah parameters (E1, E2, and E3). The oscillator strengths and the intensity parameters Omega2, Omega4 and Omega6 have been determined by the Judd-Ofelt theory, which in turn provide the radiative transition probability (A), total transition probability (A(T)), radiative lifetime (tauR) and branching ratio (beta) for the fluorescent level 4F3/2. The lasing efficiency of the prepared glasses has been characterized by the spectroscopic quality factor (Omega4/Omega6), the value of which is in the range of 0.2-1.5, typical for Nd3+ in different laser hosts. Nephelauxetic effect results in a red shift in the energy levels of Nd3+ for chloroborate glass. The radiative transition probability of the potential lasing transition 4F3/2-->4I11/2 of Nd3+ ions is found to be higher for flouroborate as compared to chloroborate glass.

A Systematic Transport and Thermodynamic Study of Heavy Transition Metal Oxides with Hexagonal Structure

NASA Astrophysics Data System (ADS)

Butrouna, Kamal

There is no apparent, dominant interaction in heavy transition metal oxides (TMO), especially in 5d-TMO, where all relevant interactions are of comparable energy scales, and therefore strongly compete. In particular, the spin-orbit interaction (SOI) strongly competes with the electron-lattice and on-site Coulomb interaction (U). Therefore, any tool that allows one to tune the relative strengths of SOI and U is expected to offer an opportunity for the discovery and study of novel materials. BaIrO3 is a magnetic insulator driven by SOI, whereas the isostructural BaRuO3 is a paramagnetic metal. The contrasting ground states have been shown to result from the critical role of SOI in the iridate. This dissertation thoroughly examines a wide array of newly observed novel phenomena induced by adjusting the relative strengths of SOI and U via a systematic chemical substitution of the Ru4+(4d 4) ions for Ir4+(5d5) ions in BaIrO3, i.e., in high quality single crystals of BaIr1--x RuxO3(0.0 ≤ x ≤ 1.0). Our investigation of structural, magnetic, transport and thermal properties reveals that Ru substitution directly rebalances the competing energies so profoundly that it generates a rich phase diagram for BaIr 1--xRuxO 3 featuring two major effects: (1) Light Ru doping (0 ≤ x ≤ 0.15) prompts a simultaneous and precipitous drop in both the magnetic ordering temperature TC and the electrical resistivity, which exhibits metal-insulator transition at around TC. (2) Heavier Ru doping (0.41 ≤ x ≤ 0.82) induces a robust metallic and spin frustration state. For comparison and contrast, we also substituted Rh4+(4d 5) ions for Ir4+(5d5) ions in BaIrO3, i.e. in BaIr1--xRhxO 3(0.0 ≤ x ≤ 0.1), where Rh only reduces the SOI, but without altering the band filling. Hence, this system remains tuned at the Mott instability and is very susceptible to disorder scattering which gives rise to Anderson localization. KEYWORDS: spin-orbit interaction, heavy transition metal oxides

Orbital Dynamics of Candidate Transitional Millisecond Pulsar 3FGL J1544.6-1125: An unusually face-on system

NASA Astrophysics Data System (ADS)

Britt, Christopher T.; Strader, Jay; Chomiuk, Laura; Halpern, Jules P.; Tremou, Evangelina; Peacock, Mark; Salinas, Ricardo

2018-01-01

We present the orbital solution for the donor star of the candidate transitional millisecond pulsar 3FGL J1544.6-1125, currently observed as an accreting low-mass X-ray binary. The orbital period is 0.2415361(36) days, entirely consistent with the spectral classification of the donor star as a mid to late K dwarf. The semi-amplitude of the radial velocity curve is exceptionally low at K2=39.3+/-1.5 km s-1, implying a remarkably face-on inclination in the range 5-8o, depending on the neutron star and donor masses. After determining the veiling of the secondary, we derive a distance to the binary of 3.8+/-0.7 kpc, yielding a 0.3-10 keV X-ray luminosity of 6.1+/-1.9 x1033 erg s-1, similar to confirmed transitional millisecond pulsars. As face-on binaries rarely occur by chance, we discuss the possibility that Fermi-selected samples of transitional milli-second pulsars in the sub-luminous disk state are affected by beaming. By phasing emission line strength on the spectroscopic ephemeris, we find coherent variations, and argue that some optical light originates from emission from an asymmetric shock originating near the inner disk.

APOSTLE: 11 TRANSIT OBSERVATIONS OF TrES-3b

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

Kundurthy, P.; Becker, A. C.; Agol, E.

2013-02-10

The Apache Point Survey of Transit Lightcurves of Exoplanets (APOSTLE) observed 11 transits of TrES-3b over two years in order to constrain system parameters and look for transit timing and depth variations. We describe an updated analysis protocol for APOSTLE data, including the reduction pipeline, transit model, and Markov Chain Monte Carlo analyzer. Our estimates of the system parameters for TrES-3b are consistent with previous estimates to within the 2{sigma} confidence level. We improved the errors (by 10%-30%) on system parameters such as the orbital inclination (i {sub orb}), impact parameter (b), and stellar density ({rho}{sub *}) compared to previousmore » measurements. The near-grazing nature of the system, and incomplete sampling of some transits, limited our ability to place reliable uncertainties on individual transit depths and hence we do not report strong evidence for variability. Our analysis of the transit timing data shows no evidence for transit timing variations and our timing measurements are able to rule out super-Earth and gas giant companions in low-order mean motion resonance with TrES-3b.« less

Lifetimes and Oscillator Strengths for Ultraviolet Transitions in P II, Cl II and Cl III

NASA Technical Reports Server (NTRS)

Cheng, S.; Federman, S. R.; Schectman, R. M.; Brown, M.; Irving, R. E.; Fritts, M. C.; Gibson, N. D.

2006-01-01

Oscillator strengths for transitions in P II, Cl II and Cl III are derived from lifetimes and branching factions measured with beam-foil techniques. The focus is on the multiplets with a prominent interstellar line at 1153 A in P II which is seen in spectra of hot stars, and the lines at 1071 A in Cl II and 1011 A in Cl III whose lines are seen in spectra of diffuse interstellar clouds and the Io torus acquired with the Far Ultraviolet Spectroscopic Explorer. These data represent the first complete set of experimental f-values for the lines in the multiplets. Our results for P II (lambda)1153 agree well with Curtis semi-empirical predictions, as well as the large scale computations by Hibbert and by Tayal. The data for Cl II (lambda)1071 also agree very well with the most recent theoretical effort and with Morton s newest recommendations. For Cl III, however, our f-values are significantly larger than those given by Morton; instead, they are more consistent with recent large-scale theoretical calculations. Extensive tests provide confirmation that LS coupling rules apply to the transitions for the multiplets in Cl II and Cl III.

[Influences of R2O-Al2O3-B2O3-SiO2 system glass and superfine alpha-Al2O3 on the sintering and phase transition of hydroxyapatite ceramics].

PubMed

Wang, Zhiqiang; Chen, Xiaoxu; Cai, Yingji; Lü, Bingling

2003-06-01

The effects of R2O-Al2O3-B2O3-SiO2 system glass and superfine alpha-Al2O3 on the sintering and phase transition of hydroxyapatite (HAP) ceramics were assessed. The results showed that alpha-Al2O3 impeded the sintering of HAP and raised the sintering temperature. When glass and alpha-Al2O3 were used together to reinforce HAP ceramics, better results could be obtained; the bending strength of multiphase HAP ceramics approached 106 MPa when 10% (wt) alpha-Al2O3 and 20%(wt) glass were used and sintered at 1200 for 1 h.

Supporting Early Adolescent Learning and Social Strengths: Promoting Productive Contexts for Students At-Risk for EBD during the Transition to Middle School

ERIC Educational Resources Information Center

Farmer, Thomas W.; Hamm, Jill V.; Petrin, Robert A.; Robertson, Dylan; Murray, Robert A.; Meece, Judith L.; Brooks, Debbie Sprott

2010-01-01

This study involved a pilot examination of the impact of the Supporting Early Adolescent Learning and Social Strengths (SEALS) model on the 6th grade academic and social context following the transition to middle school. Two middle schools from a high poverty Appalachian school district were randomly assigned to the intervention and control…

Competition of superconductivity with the structural transition in M o 3 S b 7

DOE PAGES

Ye, G. Z.; Cheng, J. -G.; Yan, Jiaqiang; ...

2016-12-14

Prior to the superconducting transition at T c ≈ 2.3 K, Mo 3Sb 7 undergoes a symmetry-lowering, cubic-to-tetragonal structural transition at T s = 53 K. In this paper, we have monitored the pressure dependence of these two transitions by measuring the resistivity of Mo 3Sb 7 single crystals under various hydrostatic pressures up to 15 GPa. The application of external pressure enhances T c but suppresses T s until P c ≈ 10 GPa, above which a pressure-induced first order structural transition takes place and is manifested by the phase coexistence in the pressure range 8 ≤ P ≤more » 12 GPa. The cubic phase above 12 GPa is also found to be superconducting with a higher T c ≈ 6 K that decreases slightly with further increasing pressure. The variations with pressure of T c and T s satisfy the Bilbro-McMillan equation, i.e. T c nT s 1-n = constant, thus suggesting the competition of superconductivity with the structural transition that has been proposed to be accompanied with a spin-gap formation at T s. Finally, this scenario is supported by our first-principles calculations which imply the plausible importance of magnetism that competes with the superconductivity in Mo 3Sb 7.« less

Photoluminescence of RbCaF3:Mn2+: the influence of phase transitions

NASA Astrophysics Data System (ADS)

Marcode Lucas, M. C.; Rodriguez, F.; Moreno, M.

1993-03-01

Precise photoluminescence measurements on an RbCaF3:Mn2+ sample containing only 400 p.p.m. of Mn2+ have been carried out in the 10-300 K temperature range. The results are compared with those obtained in other fluoroperovskites doped with Mn2+. The analysis of the 6A1g(S) to 4T1g(G) excitation peak at room temperature leads to a Mn2+-F- distance R=213.3 pm which is close to that derived from the experimental isotropic superhyperfine constant, As. The plot of the first moment of the emission band, M1, against temperature reveals a slight but sensible change of slope at T=193 K which is associated with the Oh1 to D4h18 structural phase transition of the host lattice. Furthermore, at T=40 K, M1 undergoes an abrupt increase of approximately 100 cm-1. This fact supports the existence of another phase transition involving an increase Delta R/R approximately=0.2% upon cooling, and thus a situation which is similar to that detected in the structural phase transition of KMnF3 at Tc3=81.5 K. To the authors' knowledge this is the first time that clear evidence of both phase transitions in RbCaF3 has been achieved through an optical probe. Finally the variation of the 4A1g(G), 4Eg(G) peak, E3, along the fluoroperovskite series is analysed.

Low-lying electric-dipole strengths of Ca, Ni, and Sn isotopes imprinted on total reaction cross sections

NASA Astrophysics Data System (ADS)

Horiuchi, W.; Hatakeyama, S.; Ebata, S.; Suzuki, Y.

2017-08-01

Low-lying electric-dipole (E 1 ) strength of a neutron-rich nucleus contains information on neutron-skin thickness, deformation, and shell evolution. We discuss the possibility of making use of total reaction cross sections on 40Ca, 120Sn, and 208Pb targets to probe the E 1 strength of neutron-rich Ca, Ni, and Sn isotopes. They exhibit large enhancement of the E 1 strength at neutron number N >28 , 50, and 82, respectively, due to a change of the single-particle orbits near the Fermi surface participating in the transitions. The density distributions and the electric-multipole strength functions of those isotopes are calculated by the Hartree-Fock+BCS and the canonical-basis-time-dependent-Hartree-Fock-Bogoliubov methods, respectively, using three kinds of Skyrme-type effective interaction. The nuclear and Coulomb breakup processes are respectively described with the Glauber model and the equivalent photon method in which the effect of finite-charge distribution is taken into account. The three Skyrme interactions give different results for the total reaction cross sections because of different Coulomb breakup contributions. The contribution of the low-lying E 1 strength is amplified when the low-incident energy is chosen. With an appropriate choice of the incident energy and target nucleus, the total reaction cross section can be complementary to the Coulomb excitation for analyzing the low-lying E 1 strength of unstable nuclei.

Lifetime measurements and oscillator strengths in singly ionized scandium and the solar abundance of scandium

NASA Astrophysics Data System (ADS)

Pehlivan Rhodin, A.; Belmonte, M. T.; Engström, L.; Lundberg, H.; Nilsson, H.; Hartman, H.; Pickering, J. C.; Clear, C.; Quinet, P.; Fivet, V.; Palmeri, P.

2017-12-01

The lifetimes of 17 even-parity levels (3d5s, 3d4d, 3d6s and 4p2) in the region 57 743-77 837 cm-1 of singly ionized scandium (Sc II) were measured by two-step time-resolved laser induced fluorescence spectroscopy. Oscillator strengths of 57 lines from these highly excited upper levels were derived using a hollow cathode discharge lamp and a Fourier transform spectrometer. In addition, Hartree-Fock calculations where both the main relativistic and core-polarization effects were taken into account were carried out for both low- and high-excitation levels. There is a good agreement for most of the lines between our calculated branching fractions and the measurements of Lawler & Dakin in the region 9000-45 000 cm-1 for low excitation levels and with our measurements for high excitation levels in the region 23 500-63 100 cm-1. This, in turn, allowed us to combine the calculated branching fractions with the available experimental lifetimes to determine semi-empirical oscillator strengths for a set of 380 E1 transitions in Sc II. These oscillator strengths include the weak lines that were used previously to derive the solar abundance of scandium. The solar abundance of scandium is now estimated to logε⊙ = 3.04 ± 0.13 using these semi-empirical oscillator strengths to shift the values determined by Scott et al. The new estimated abundance value is in agreement with the meteoritic value (logεmet = 3.05 ± 0.02) of Lodders, Palme & Gail.

Impacts of Irrigation on Land-Atmosphere Coupling Strength Under Different Evapotranspiration Characteristics

NASA Astrophysics Data System (ADS)

Liao, C. Y.; Lo, M. H.

2017-12-01

The Budyko curve displays that the magnitude of evapotranspiration (ET) is limited mainly by the availabilities of energy and water, i.e., under wet conditions, ET is primarily controlled by the available energy, while under dry conditions, ET is primarily controlled by the available water. Land-atmosphere coupling (LAC) strength, which relates to the Budyko curve, is widely discussed because of its contribution towards the improvement in seasonal climate forecasts. For example, the "hot spots" of LAC, where the soil moisture anomalies strongly affect the local precipitation, are found in the transition zones between wet and dry climates. ET of these transition zones is limited by the available water, but at the same time, the surface latent heat flux is large enough to trigger moist convection. Recently, the impacts of irrigation have gained lots of attention, including the change in LAC. Badger and Dirmeyer (2015) analyzed the climate response of Amazon forest replacement by crop with consideration of irrigation in model simulations, discovering negative relationship between added irrigation water and coupling between the soil moisture and the latent heat flux. In addition, Lu et al. (2017) found remarkable decreases of LAC strength with the increase of irrigated cropland percentage in the Great Plains of America. The two studies show that irrigation is possible to affect land-atmosphere coupling strength. However, whether the irrigation process leads to the reduction of coupling strength in other regions of the world remains unclear. This study aims to compare the differences of irrigation impact on land-atmosphere coupling strength between five selected locations undergoing intense irrigation: India, North China Plain, Southwest Europe, Great Plains and Middle East. The spatial divergence of the factor that limits the ET (e.g., either by the available energy or water) will be the focus in this study. Both offline simulation (Community Land Model) and couple

SU-E-T-155: Calibration of Variable Longitudinal Strength 103Pd Brachytherapy Sources

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

Reed, J; Radtke, J; Micka, J

Purpose: Brachytherapy sources with variable longitudinal strength (VLS) allow for a customized intensity along the length of the source. These have applications in focal brachytherapy treatments of prostate cancer where dose boosting can be achieved through modulation of intra-source strengths. This work focused on development of a calibration methodology for VLS sources based on measurements and Monte Carlo (MC) simulations of five 1 cm {sup 10} {sup 3}Pd sources each containing four regions of variable {sup 103}Pd strength. Methods: The air-kerma strengths of the sources were measured with a variable-aperture free-air chamber (VAFAC). Source strengths were also measured using amore » well chamber. The in-air azimuthal and polar anisotropy of the sources were measured by rotating them in front of a NaI scintillation detector and were calculated with MC simulations. Azimuthal anisotropy results were normalized to their mean intensity values. Polar anisotropy results were normalized to their average transverse axis intensity values. The relative longitudinal strengths of the sources were measured via on-contact irradiations with radiochromic film, and were calculated with MC simulations. Results: The variable {sup 103}Pd loading of the sources was validated by VAFAC and well chamber measurements. Ratios of VAFAC air-kerma strengths and well chamber responses were within ±1.3% for all sources. Azimuthal anisotropy results indicated that ≥95% of the normalized values for all sources were within ±1.7% of the mean values. Polar anisotropy results indicated variations within ±0.3% for a ±7.6° angular region with respect to the source transverse axis. Locations and intensities of the {sup 103}Pd regions were validated by radiochromic film measurements and MC simulations. Conclusion: The calibration methodology developed in this work confirms that the VLS sources investigated have a high level of polar uniformity, and that the strength and longitudinal intensity

Mechanism and microstructures in Ga2O3 pseudomartensitic solid phase transition.

PubMed

Zhu, Sheng-Cai; Guan, Shu-Hui; Liu, Zhi-Pan

2016-07-21

Solid-to-solid phase transition, although widely exploited in making new materials, challenges persistently our current theory for predicting its complex kinetics and rich microstructures in transition. The Ga2O3α-β phase transformation represents such a common but complex reaction with marked change in cation coordination and crystal density, which was known to yield either amorphous or crystalline products under different synthetic conditions. Here we, via recently developed stochastic surface walking (SSW) method, resolve for the first time the atomistic mechanism of Ga2O3α-β phase transformation, the pathway of which turns out to be the first reaction pathway ever determined for a new type of diffusionless solid phase transition, namely, pseudomartensitic phase transition. We demonstrate that the sensitivity of product crystallinity is caused by its multi-step, multi-type reaction pathway, which bypasses seven intermediate phases and involves all types of elementary solid phase transition steps, i.e. the shearing of O layers (martensitic type), the local diffusion of Ga atoms (reconstructive type) and the significant lattice dilation (dilation type). While the migration of Ga atoms across the close-packed O layers is the rate-determining step and yields "amorphous-like" high energy intermediates, the shearing of O layers contributes to the formation of coherent biphase junctions and the presence of a crystallographic orientation relation, (001)α//(201[combining macron])β + [120]α//[13[combining macron]2]β. Our experiment using high-resolution transmission electron microscopy further confirms the theoretical predictions on the atomic structure of biphase junction and the formation of (201[combining macron])β twin, and also discovers the late occurrence of lattice expansion in the nascent β phase that grows out from the parent α phase. By distinguishing pseudomartensitic transition from other types of mechanisms, we propose general rules to predict the

Warrior Transition Leader: Medical Rehabilitation Handbook

DTIC Science & Technology

2011-01-01

serve. rE f E r E n c E S 1. http://www.army.mil/warriorcarenews/. Accessed January 24, 2011. 2. Warrior Transition Command Web site. http...www.wtc.army.mil/about_us/ ctp.html. Accessed January 24, 2011. 3. Leipold JD. Warrior Transition Command stands up at Pentagon. US Army Web site. Army...January 24, 2011. 4. Warrior Transition Command Web site. http://wtc.armylive.dodlive.mil/ about-wtu/. Accessed January 24, 2011. 5. Leipold JD

Strength and Deformation of Solid Krypton and Xenon to Mbar Pressures

NASA Astrophysics Data System (ADS)

Brugman, B. L.; Lv, M.; Liu, J.; Park, C.; Popov, D.; Prakapenka, V. B.; Dorfman, S.

2017-12-01

Studying phase equilibria and deformation of rare gas solids (RGS) under pressure provides insight into their behavior in planetary bodies. Their simple bonding properties make them useful analogs for materials with similar structures and other van der Waals bonded materials. He, Ne, and Ar are useful as pressure-transmitting media in diamond anvil cell (DAC) experiments due to their low strength and inert chemistry, and Xe has been proposed as a pressure medium as well, but relatively little is known about the strength of Kr and Xe. The strength of heavy RGS may be affected by a martensitic transition from fcc to hcp structure, which is observed at lower pressures with higher Z. The pressure ranges of this transition in Kr and Xe in previous experimental and computational studies vary from 5 to 29 GPa for Xe and as high as 130 GPa for Kr. The transition may be further complicated by kinetics and multiple transition mechanisms. Modeling of phase equilibria and evaluation of Kr and Xe as pressure media may be improved by examination of elastic and plastic properties at extreme pressure. We studied phase transitions and deformation of Kr and Xe using synchrotron x-ray diffraction at Advanced Photon Source beamlines 13-ID-D and 16-BM-D in the DAC at pressures up to 118 GPa. The martensitic fcc-hcp phase transition begins as peak asymmetry and weak peaks in both Kr and Xe at pressures as low as 5 GPa. Intensity of hcp peaks in Xe increases continuously to 118 GPa. Weak hcp peaks were evident in Kr alongside fcc peaks from 5 to 94 GPa, contrary to theoretical predictions that the hcp transition does not begin below 110-130 GPa. Strength and plasticity of Kr and Xe were obtained by complementary lattice strain and peak width analysis of diffraction patterns in both axial and radial geometries as well as observation of pressure gradients by ruby fluorescence. Xe is approximately hydrostatic with strength comparable to common pressure media at pressures up to 10-12 GPa

Crystal Field Splitting is Limiting the Stability and Strength of Ultra-incompressible Orthorhombic Transition Metal Tetraborides

PubMed Central

Zhang, R. F.; Wen, X. D.; Legut, D.; Fu, Z. H.; Veprek, S.; Zurek, E.; Mao, H. K.

2016-01-01

The lattice stability and mechanical strengths of the supposedly superhard transition metal tetraborides (TmB4, Tm = Cr, Mn and Fe) evoked recently much attention from the scientific community due to the potential applications of these materials, as well as because of general scientific interests. In the present study, we show that the surprising stabilization of these compounds from a high symmetry to a low symmetry structure is accomplished by an in-plane rotation of the boron network, which maximizes the in-plane hybridization by crystal field splitting between d orbitals of Tm and p orbitals of B. Studies of mechanical and electronic properties of TmB4 suggest that these tetraborides cannot be intrinsically superhard. The mechanical instability is facilitated by a unique in-plane or out-of-plane weakening of the three-dimensional covalent bond network of boron along different shear deformation paths. These results shed a novel view on the origin of the stability and strength of orthorhombic TmB4, highlighting the importance of combinational analysis of a variety of parameters related to plastic deformation of the crystalline materials when attempting to design new ultra-incompressible, and potentially strong and hard solids. PMID:26976479

Trunk strength and mobility changes in children with slow transit constipation.

PubMed

Chase, Janet W; Stillman, Barry C; Gibb, Susan M; Clarke, Melanie C C; Robertson, Val J; Catto-Smith, Anthony G; Hutson, John M; Southwell, Bridget R

2009-12-01

It appears that there are no published reports on childhood slow transit constipation (STC) that have considered the state of the musculoskeletal components of the trunk in these children. The present study aimed to determine whether children with STC have different trunk musculoskeletal characteristics that might be related to their defecation difficulties, compared to controls. With the aid of computer-analyzed photographs and clinical testing, 41 children with STC and 41 age-matched controls were examined for Marfanoid features, sitting posture, spinal joint mobility and trunk muscle strength. The latter was assessed by measuring maximum voluntary abdominal bulging and retraction in sitting, and active trunk extension in prone-lying. Levels of general exercise and sedentary activities were evaluated by questionnaire. STC subjects were more slumped in relaxed sitting (P < or = 0.001), less able to bulge (P < or = 0.03) and less able to actively extend the trunk (P = 0.02) compared to controls. All subjects sat more erect during abdominal bulging (P < or = 0.03). The results show that STC children have reduced trunk control and posture, which indicates that clinicians should include training of trunk muscles and correction of sitting posture. There was no evidence that children with STC exercised less than the controls.

Stretch-collapse transition of polyelectrolyte brushes in a poor solvent

NASA Astrophysics Data System (ADS)

von Goeler, F.; Muthukumar, M.

1996-12-01

This paper describes the behavior of charged, polymer brushes in electrolyte solutions of varying solvent quality. The brush height, d, dependence on the chain length, L (=Nl, where l is the Kuhn length), the grafting density σ, and solvent conditions is determined. We consider a monomer-monomer potential consisting of three components: (1) a long-ranged, screened Coulombic component of strength v¯/l (l is the Kuhn length) and range κ-1; (2) a short-ranged, two-body component of strength w¯l; and (3) a short-ranged, three-body component of strength ūl3. In particular, we examine the transition from a stretched state to a collapsed state in a poor solvent (w¯<0) as the solvent quality is decreased. Using dimensional analysis, Monte Carlo methods, and a variational technique, a first order transition is observed as predicted by the scaling arguments of Ross et al. and Borisov et al. for high charge/grafting densities. Using a variational procedure, we derive an analytical expression for the brush size and determine, quantitatively, the critical conditions for a first order transition in terms of key dimensionless variables, vN5/2, κlN1/2, wN3/2, and uN2 (where v=2πσl2v¯, w=σl2w¯, and u=σ2l4ū).

Bond strength comparison of 2 self-etching primers over a 3-month storage period.

PubMed

Trites, Brian; Foley, Timothy F; Banting, David

2004-12-01

The purpose of this in vitro study was to evaluate the shear-peel bond strength of 2 self-etching primer systems, Transbond Plus (3M/ Unitek, Monrovia, Calif) and First Step (Reliance Orthodontic Products, Itasca, Ill), with their respective adhesives, and compare them with a control adhesive system (Transbond XT, 3M/ Unitek) over a 3-month period. Two hundred seventy extracted human premolars were obtained and randomly divided into 9 groups of 30 teeth. Metal orthodontic brackets were bonded to the enamel, and each adhesive group was stored for 24 horrs (T1), 30 days (T2), or 3 months (T3) in deionized water at 37 degrees C. All bonded specimens were thermocycled at 10 degrees C and 50 degrees C for 24 hours before debonding. Brackets were debonded by using a shear-peel load on a testing machine at a cross-head speed of 2 mm/min. Bond failure was also evaluated. The shear-peel bond strengths of the 3 bonding systems were clinically acceptable with the possible exception of First Step at 30-day storage. Repeated measures analysis of variance showed a statistically significant (P < .0001) difference in mean bond strengths between the 3 adhesive systems. The shear-peel bond strength of the adhesives over the 3 time intervals showed statistically significant (P = .005) changes. In each group, there were statistically significant differences in shear-peel bond strength between time intervals T1-T2 and T2-T3 for Transbond Plus and T2-T3 for First Step. The change in mean shear-peel bond strength of the 3 adhesives demonstrated a consistent pattern of behavior over the 3 storage intervals. The lowest mean shear-peel bond strength values were noted at the 30-day storage. Bond failure analysis (adhesive remnant index) demonstrated mainly cohesive bond failures.

The transition mechanisms of the E to H mode and the H to E mode in an inductively coupled argon-mercury mixture discharge

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

Zhang, Xiao; Yu, Peng-Cheng; Liu, Yu

2015-10-15

In our experiment, the transition points between the two operational modes of capacitive coupling (E mode) and inductive coupling (H mode) were investigated at a wide range of mercury vapor pressures in an inductively coupled plasma, varying with the input radio-frequency powers and the total filling pressures (10 Pa–30 Pa). The electron temperatures were calculated versus with the mercury vapor pressures for different values of the total filling pressures. The transition power points and electron density also were measured in this study. It is shown that the transition powers, whether the E to H mode transition or the H to E modemore » transition, are lower than that of the argon discharge, and these powers almost increase with the mercury vapor pressure rising. However, the transition electron density follows an inverse relationship with the mercury vapor pressures compared with the transition powers. In addition, at the lower pressures and higher mercury vapor pressures, an inverse hysteresis was observed clearly, which did not appear in the argon gas plasma. We suggest that all these results are attributed to the electron-neutral collision frequency changed with the additional mercury vapor pressures.« less

VizieR Online Data Catalog: Eu III oscillator strengths (Masonkina+, 2002)

NASA Astrophysics Data System (ADS)

Masonkina, L. I.; Ryabtsev, A. N.; Ryabchikova, T. A.

2002-04-01

The calculations of the spectrum and oscillator strengths for the 4f7-(4f65d+4f66s) Eu III transitions. The calculations were performed with Cowan's RCN-RCG-RCE codes in the single-configuration approximation. The new oscillator strengths were tested by analyzing the Europium abundances using Eu II and Eu III lines in the spectra of hot peculiar stars (α2 CVn is a typical representative) and a cool peculiar stars (β CrB is a typical representative). (3 data files).

CsPbBr3 perovskites: Theoretical and experimental investigation on water-assisted transition from nanowire formation to degradation

NASA Astrophysics Data System (ADS)

Akbali, B.; Topcu, G.; Guner, T.; Ozcan, M.; Demir, M. M.; Sahin, H.

2018-03-01

Recent advances in colloidal synthesis methods have led to an increased research focus on halide perovskites. Due to the highly ionic crystal structure of perovskite materials, a stability issue pops up, especially against polar solvents such as water. In this study, we investigate water-driven structural evolution of CsPbBr3 by performing experiments and state-of-the-art first-principles calculations. It is seen that while an optical image shows the gradual degradation of the yellowish CsPbBr3 structure under daylight, UV illumination reveals that the degradation of crystals takes place in two steps: transition from a blue-emitting to green-emitting structure and and then a transition from a green-emitting phase to complete degradation. We found that as-synthesized CsPbBr3 nanowires (NWs) emit blue light under a 254 nm UV source. Before the degradation, first, CsPbBr3 NWs undergo a water-driven structural transition to form large bundles. It is also seen that formation of such bundles provides longer-term environmental stability. In addition theoretical calculations revealed the strength of the interaction of water molecules with ligands and surfaces of CsPbBr3 and provide an atomistic-level explanation to a transition from ligand-covered NWs to bundle formation. Further interaction of green-light-emitting bundles with water causes complete degradation of CsPbBr3 and the photoluminescence signal is entirely quenched. Moreover, Raman and x-ray-diffraction measurements revealed that completely degraded regions are decomposed to PbBr2 and CsBr precursors. We believe that the findings of this study may provide further insight into the degradation mechanism of CsPbBr3 perovskite by water.

Relationship of maximum strength to weightlifting performance.

PubMed

Stone, Michael H; Sands, William A; Pierce, Kyle C; Carlock, Jon; Cardinale, Marco; Newton, Robert U

2005-06-01

The primary objective was to assess the relationship of maximum strength to weightlifting ability using established scaling methods. The secondary objective was to compare men and women weightlifters on strength and weightlifting ability. Two correlational observations were carried out using Pearson's r. In the first observation (N = 65) the relationship of dynamic maximum strength (one-repetition maximum (1RM) squat) was compared with weightlifting ability; in the second observation (N = 16), isometric maximum strength (midthigh pull) was studied. Scaling methods for equating maximum strength and weightlifting results were used (load x (Ht), load x kg, load x lbm(-1), allometric, and Sinclair formula) to assess the association between measures of maximum strength and weightlifting performance. Using scaled values; correlations between maximum strength and weightlifting results were generally strong in both observations (e.g., using allometric scaling for the 1RM squat vs the 1RM snatch: r = 0.84, N = 65). Men were stronger than women (e.g., 1RM squat, N = 65: men = 188.1 +/- 48.6 kg; women = 126.7 +/- 28.3 kg); differences generally held when scaling was applied (e.g., 1RM squat scaled with the Sinclair formula: men = 224.7 +/- 36.5 kg; women = 144.2 +/- 25.4 kg). When collectively considering scaling methods, maximum strength is strongly related to weightlifting performance independent of body mass and height differences. Furthermore, men are stronger than women even when body mass and height are obviated by scaling methods.

Gamow-Teller transitions in the 64Ni(3He, t)64Cu reaction

NASA Astrophysics Data System (ADS)

Popescu, L.; Adachi, T.; Berg, G. P. A.; von Brentano, P.; De Frenne, D.; Fujita, K.; Fujita, Y.; Hatanaka, K.; Jacobs, E.; Negret, A.; Nakanishi, K.; Sakemi, Y.; Shimbara, Y.; Shimizu, Y.; Tameshige, Y.; Tamii, A.; Uchida, M.; Yosoi, M.

2005-10-01

In order to study the Gamow-Teller (GT) transitions in the fp-shell nucleus 64Cu, the 64Ni(3He, t)64Cu charge-exchange reaction was investigated at E3He= 140 MeV/nucleon [1]. The outgoing tritons were momentum analysed by the Grand Raiden spectrometer at 0°. The very high energy resolution of 35 keV (FWHM) allowed the separation of individual levels in the excitation energy region from 0 to 3.5 MeV. An angular distribution analysis was performed for the observed transitions to these states. In addition to the ground state (g.s.), known to be a Jπ = 1+ GT state, several excited states showed L = 0 nature, making them candidates of GT states. At higher excitation energies, the level density becomes very high and a bump-like structure, the so-called GT Giant Resonance, dominates the spectrum.

Spectroscopy of the hydrogen 1 S -3 S transition with chirped laser pulses

NASA Astrophysics Data System (ADS)

Yost, D. C.; Matveev, A.; Grinin, A.; Peters, E.; Maisenbacher, L.; Beyer, A.; Pohl, R.; Kolachevsky, N.; Khabarova, K.; Hänsch, T. W.; Udem, Th.

2016-04-01

We identify a systematic present in two-photon direct frequency comb spectroscopy (DFCS) which is a result of chirped laser pulses and is a manifestation of the first-order Doppler effect. We carefully analyze this systematic and propose methods for its mitigation within the context of our measurement of the hydrogen 1 S -3 S transition. We also report on our determination of the absolute frequency of this transition, which is comparable to a previous measurement using continuous-wave spectroscopy [O. Arnoult et al., Eur. Phys. J. D 60, 243 (2010), 10.1140/epjd/e2010-00249-6], but was obtained with a different experimental method.

Nonradiative transition dynamics in alexandrite

NASA Technical Reports Server (NTRS)

Gayen, S. K.; Wang, W. B.; Petricevic, V.; Alfano, R. R.

1986-01-01

The first direct picosecond time-resolved measurement of the nonradiative transition dynamics between the excited 4T2 pump band and the metastable 2E storage level of the trivalent chromium ion in alexandrite is reported. The nonradiative relaxation times of 17 ps for intra-4T2 vibrational transitions, and 27 ps for 4T2-2E electronic transition are obtained. The thermal repopulation rate of the 4T2 state from the metastable 2E level is of the order 3.5 x 10 to the 9th per s.

Large low-energy M1 strength for ^{56,57}Fe within the nuclear shell model.

PubMed

Brown, B Alex; Larsen, A C

2014-12-19

A strong enhancement at low γ-ray energies has recently been discovered in the γ-ray strength function of ^{56,57}Fe. In this work, we have for the first time obtained theoretical γ decay spectra for states up to ≈8  MeV in excitation for ^{56,57}Fe. We find large B(M1) values for low γ-ray energies that provide an explanation for the experimental observations. The role of mixed E2 transitions for the low-energy enhancement is addressed theoretically for the first time, and it is found that they contribute a rather small fraction. Our calculations clearly show that the high-ℓ(=f) diagonal terms are most important for the strong low-energy M1 transitions. As such types of 0ℏω transitions are expected for all nuclei, our results indicate that a low-energy M1 enhancement should be present throughout the nuclear chart. This could have far-reaching consequences for our understanding of the M1 strength function at high excitation energies, with profound implications for astrophysical reaction rates.

Energy levels and radiative transition rates for Ge XXXI, As XXXII, and Se XXXIII

NASA Astrophysics Data System (ADS)

Aggarwal, Sunny; Singh, J.; Jha, A. K. S.; Mohan, Man

2014-07-01

Fine-structure energies of the 67 levels belonging to the 1s2, 1s 2l, 1s3l, 1s4l, 1s5l, and 1s6l configurations of Ge XXXI, As XXXII, and Se XXXIII have been calculated using the General-Purpose Relativistic Atomic Structure Package. In addition, radiative rates, oscillator strengths, transition wavelengths, and line strengths have been calculated for all electric dipole, magnetic dipole, electric quadrupole, and magnetic quadrupole transitions among these levels. Lifetimes are also presented for all excited levels of these three ions. We have compared our results with the results available in the literature and the accuracy of the data is assessed. We predict new energy levels, oscillator strengths, and transition probabilities where no other theoretical or experimental results are available, which will form the basis for future experimental work.

Monitoring a Silent Phase Transition in CH 3NH 3PbI 3 Solar Cells via Operando X-ray Diffraction

DOE PAGES

Schelhas, Laura T.; Christians, Jeffrey A.; Berry, Joseph J.; ...

2016-10-13

The relatively modest temperature of the tetragonal-to-cubic phase transition in CH 3NH 3PbI 3 perovskite is likely to occur during real world operation of CH 3NH 3PbI 3 solar cells. In this work, we simultaneously monitor the structural phase transition of the active layer along with solar cell performance as a function of the device operating temperature. The tetragonal to cubic phase transition is observed in the working device to occur reversibly at temperatures between 60.5 and 65.4 degrees C. In these operando measurements, no discontinuity in the device performance is observed, indicating electronic behavior that is insensitive to themore » structural phase transition. Here, this decoupling of device performance from the change in long-range order across the phase transition suggests that the optoelectronic properties are primarily determined by the local structure in CH 3NH 3PbI 3. That is, while the average crystal structure as probed by X-ray diffraction shows a transition from tetragonal to cubic, the local structure generally remains well characterized by uncorrelated, dynamic octahedral rotations that order at elevated temperatures but are unchanged locally.« less

Monitoring a Silent Phase Transition in CH 3NH 3PbI 3 Solar Cells via Operando X-ray Diffraction

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

Schelhas, Laura T.; Christians, Jeffrey A.; Berry, Joseph J.

The relatively modest temperature of the tetragonal-to-cubic phase transition in CH 3NH 3PbI 3 perovskite is likely to occur during real world operation of CH 3NH 3PbI 3 solar cells. In this work, we simultaneously monitor the structural phase transition of the active layer along with solar cell performance as a function of the device operating temperature. The tetragonal to cubic phase transition is observed in the working device to occur reversibly at temperatures between 60.5 and 65.4 degrees C. In these operando measurements, no discontinuity in the device performance is observed, indicating electronic behavior that is insensitive to themore » structural phase transition. Here, this decoupling of device performance from the change in long-range order across the phase transition suggests that the optoelectronic properties are primarily determined by the local structure in CH 3NH 3PbI 3. That is, while the average crystal structure as probed by X-ray diffraction shows a transition from tetragonal to cubic, the local structure generally remains well characterized by uncorrelated, dynamic octahedral rotations that order at elevated temperatures but are unchanged locally.« less

Radiative rates for forbidden M1 and E2 transitions of astrophysical interest in doubly ionized iron-peak elements

NASA Astrophysics Data System (ADS)

Fivet, V.; Quinet, P.; Bautista, M. A.

2016-01-01

Aims: Accurate and reliable atomic data for lowly ionized Fe-peak species (Sc, Ti, V, Cr, Mn, Fe, Co, and Ni) are of paramount importance for analyzing the high-resolution astrophysical spectra currently available. The third spectra of several iron group elements have been observed in different galactic sources, such as Herbig-Haro objects in the Orion Nebula and stars like Eta Carinae. However, forbidden M1 and E2 transitions between low-lying metastable levels of doubly charged iron-peak ions have been investigated very little so far, and radiative rates for those lines remain sparse or nonexistent. We attempt to fill that gap and provide transition probabilities for the most important forbidden lines of all doubly ionized iron-peak elements. Methods: We carried out a systematic study of the electronic structure of doubly ionized Fe-peak species. The magnetic dipole (M1) and electric quadrupole (E2) transition probabilities were computed using the pseudo-relativistic Hartree-Fock (HFR) code of Cowan and the central Thomas-Fermi-Dirac-Amaldi potential approximation implemented in AUTOSTRUCTURE. This multiplatform approach allowed for consistency checks and intercomparison and has proven very useful in many previous works for estimating the uncertainties affecting the radiative data. Results: We present transition probabilities for the M1 and E2 forbidden lines depopulating the metastable even levels belonging to the 3dk and 3dk-14s configurations in Sc III (k = 1), Ti III (k = 2), V III (k = 3), Cr III (k = 4), Mn III (k = 5), Fe III (k = 6), Co III (k = 7), and Ni III (k = 8).

Unusual Mott transition in multiferroic PbCrO 3

DOE PAGES

Wang, Shanmin; Zhu, Jinlong; Zhang, Yi; ...

2015-11-24

The Mott insulator in correlated electron systems arises from classical Coulomb repulsion between carriers to provide a powerful force for electron localization. When turning such an insulator into a metal, the so-called Mott transition, is commonly achieved by "bandwidth" control or "band filling." However, both mechanisms deviate from the original concept of Mott, which attributes such a transition to the screening of Coulomb potential and associated lattice contraction. We report a pressure-induced isostructural Mott transition in cubic perovskite PbCrO3. At the transition pressure of similar to 3 GPa, PbCrO3 exhibits significant collapse in both lattice volume and Coulomb potential. Concurrentmore » with the collapse, it transforms from a hybrid multiferroic insulator to a metal. For the first time to our knowledge, these findings validate the scenario conceived by Mott. Close to the Mott criticality at similar to 300 K, fluctuations of the lattice and charge give rise to elastic anomalies and Laudau critical behaviors resembling the classic liquid-gas transition. Moreover, the anomalously large lattice volume and Coulomb potential in the low-pressure insulating phase are largely associated with the ferroelectric distortion, which is substantially suppressed at high pressures, leading to the first-order phase transition without symmetry breaking.« less

Unusual Mott transition in multiferroic PbCrO3

PubMed Central

Wang, Shanmin; Zhu, Jinlong; Zhang, Yi; Yu, Xiaohui; Zhang, Jianzhong; Wang, Wendan; Bai, Ligang; Qian, Jiang; Yin, Liang; Sullivan, Neil S.; Jin, Changqing; He, Duanwei; Xu, Jian; Zhao, Yusheng

2015-01-01

The Mott insulator in correlated electron systems arises from classical Coulomb repulsion between carriers to provide a powerful force for electron localization. Turning such an insulator into a metal, the so-called Mott transition, is commonly achieved by “bandwidth” control or “band filling.” However, both mechanisms deviate from the original concept of Mott, which attributes such a transition to the screening of Coulomb potential and associated lattice contraction. Here, we report a pressure-induced isostructural Mott transition in cubic perovskite PbCrO3. At the transition pressure of ∼3 GPa, PbCrO3 exhibits significant collapse in both lattice volume and Coulomb potential. Concurrent with the collapse, it transforms from a hybrid multiferroic insulator to a metal. For the first time to our knowledge, these findings validate the scenario conceived by Mott. Close to the Mott criticality at ∼300 K, fluctuations of the lattice and charge give rise to elastic anomalies and Laudau critical behaviors resembling the classic liquid–gas transition. The anomalously large lattice volume and Coulomb potential in the low-pressure insulating phase are largely associated with the ferroelectric distortion, which is substantially suppressed at high pressures, leading to the first-order phase transition without symmetry breaking. PMID:26604314

Identification of forbidden vibration-rotation transitions in 15NH3

NASA Astrophysics Data System (ADS)

Urban, Š.; D'Cunha, Romola; Narahari Rao, K.

1984-07-01

Forbidden Δk - l = 3 vibration-rotation transitions have been observed in the ν4 band of 15NH3. The analysis of these transitions, together with previously published data on the allowed transitions, has made it possible to determine a set of molecular parameters, including for the first time the rotational constant C as well as the centrifugal distortion constants DK and HKKK, which are necessary for the calculation of energy levels. Some weak forbidden transitions in the ν2 band have also been observed.

Conductivity Dynamics of the Metal to Insulator Transition in EuNiO3/LANiO3 Superlattices

DTIC Science & Technology

2016-02-07

lead to emergent phenomena with the insulator -to- insulator transition (IMT) being one of the most enigmatic from fundamental and applied perspectives...2015 Approved for Public Release; Distribution Unlimited Final Report: Conductivity Dynamics of the Metal to Insulator Transition in EuNiO3/LANiO3...Conductivity Dynamics of the Metal to Insulator Transition in EuNiO3/LANiO3 Superlattices Report Title In numerous transition metal oxides (TMO

Modeling Verwey transition temperature of Fe3O4 nanocrystals

NASA Astrophysics Data System (ADS)

Jiang, Xiao bao; Xiao, Bei bei; Yang, Hong yu; Gu, Xiao yan; Sheng, Hong chao; Zhang, Xing hua

2016-11-01

The Verwey transition in nanoscale is an important physical property for Fe3O4 nanocrystals and has attracted extensive attention in recent years. In this work, an analytic thermodynamic model without any adjusting parameters is developed to estimate the size and shape effects on modulating the Verwey transition temperature of Fe3O4 nanocrystals. The results show that the Verwey transition temperature reduces with increasing shape parameter λ or decreasing size D. A good agreement between the prediction and the experimental data verified our physical insight that the Verwey transition of Fe3O4 can be directly related to the atomic thermal vibration. The results presented in this work will be of benefit to the understanding of the microscopic mechanism of the Verwey transition and the design of future generation switching and memory devices.

Enamel and dentin bond strength following gaseous ozone application.

PubMed

Cadenaro, Milena; Delise, Chiara; Antoniollo, Francesca; Navarra, Ottavia Chiara; Di Lenarda, Roberto; Breschi, Lorenzo

2009-08-01

To evaluate the effects of gaseous ozone application on enamel and dentin bond strength produced by two self-etching adhesive systems. The shear bond strength test was conducted to assess adhesion on enamel (protocol 1), while the microtensile bond strength test was performed on dentin (protocol 2). Protocol 1: 96 bovine incisors were randomly divided into 4 groups, and enamel surfaces were bonded in accordance with the following treatments: (1E) ozone + Clearfil Protect Bond; (2E) Clearfil Protect Bond (control); (3E) ozone + Xeno III; (4E) Xeno III (control). Ozone gas was applied for 80 s. Shear bond strength was measured with a universal testing machine. Protocol 2: 40 noncarious human molars were selected. Middle/deep dentin was exposed and bonded in accordance with the following treatments: (1D) ozone+Clearfil Protect Bond; (2D) Clearfil Protect Bond (control); (3D) ozone+Xeno III (4D) Xeno III (control). Four-mm-thick buildups were built on the adhesives, then specimens were sectioned in accordance with the nontrimming technique. Specimens were stressed until failure occurred, and failure modes were analyzed. Shear bond and microtensile bond strength data were analyzed using two-way ANOVA and Tukey's post-hoc test. No statistical differences were found between ozone treated specimens and controls, neither on enamel nor on dentin irrespective of the tested adhesive. Clearfil Protect Bond showed higher bond strength to enamel than Xeno III, irrespective of the ozone treatment (p < 0.05). The use of ozone gas to disinfect the cavity before placing a restoration had no influence on immediate enamel and dentin bond strength.

Metal-insulator transition, giant negative magnetoresistance, and ferromagnetism in LaCo1-yNiyO3

NASA Astrophysics Data System (ADS)

Hammer, D.; Wu, J.; Leighton, C.

2004-04-01

We have investigated the transport and magnetic properties of the perovskite LaCo1-yNiyO3, an alloy of LaCoO3 (a semiconductor that exhibits spin-state transitions) and LaNiO3 (a paramagnetic metal). The metal-insulator transition (MIT) was found to occur at y=0.40. On the insulating side of the transition the conductivity obeys Mott variable range hopping with a characteristic temperature (T0) that varies with y in a manner consistent with the predictions of the scaling theory of electron localization. On the metallic side the low temperature conductivity (down to 0.35 K) varies as T1/2 due to the effects of electron-electron interaction in the presence of disorder. The composition dependence of the low-temperature conductivity in the critical region fits the scaling theory of electron localization with a conductivity critical exponent close to unity, consistent with the scaling of T0 in the insulating phase. A large negative magnetoresistance is observed (up to 70% in 17 T) which increases monotonically with decreasing temperature and is smoothly decreased through the MIT. The magnetic properties show that doping LaCoO3 with Ni leads to a rapid destruction of the low spin-state for Co3+ ions, followed by the onset of distinct ferromagnetic interactions at higher Ni content. Similar to La1-xSrxCoO3, the system shows a smooth evolution from spin-glass to ferromagnetic ground states, which is interpreted in terms of the formation of ferromagnetic clusters. In contrast to La1-xSrxCoO3 further doping does not lead to a bulk ferromagnetlike state with a large TC, despite the clear existence of ferromagnetic interactions. We suggest that this is due to a limitation of the strength of the ferromagnetic interactions, which could be related to the fact that Ni rich clusters are not thermodynamically stable. The ferromagnetic clusters in LaCo1-yNiyO3 do not percolate with increasing y explaining the lack of a high-TC ferromagnetic state and the fact that the MIT is a simple

GROUND-BASED TRANSIT OBSERVATIONS OF THE SUPER-EARTH 55 Cnc e

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

De Mooij, E. J. W.; López-Morales, M.; Karjalainen, R.

2014-12-20

We report the first ground-based detections of the shallow transit of the super-Earth exoplanet 55 Cnc e using a 2 m class telescope. Using differential spectrophotometry, we observed one transit in 2013 and another in 2014, with average spectral resolutions of ∼700 and ∼250, spanning the Johnson BVR photometric bands. We find a white light planet-to-star radius ratio of 0.0190{sub −0.0027}{sup +0.0023} from the 2013 observations and 0.0200{sub −0.0018}{sup +0.0017} from the 2014 observations. The two data sets combined result in a radius ratio of 0.0198{sub −0.0014}{sup +0.0013}. These values are all in agreement with previous space-based results. Scintillation noise in themore » data prevents us from placing strong constraints on the presence of an extended hydrogen-rich atmosphere. Nevertheless, our detections of 55 Cnc e in transit demonstrate that moderate-sized telescopes on the ground will be capable of routine follow-up observations of super-Earth candidates discovered by the Transiting Exoplanet Survey Satellite around bright stars. We expect it also will be possible to place constraints on the atmospheric characteristics of those planets by devising observational strategies to minimize scintillation noise.« less

Transiting Exoplanet Monitoring Project (TEMP). IV. Refined System Parameters, Transit Timing Variations, and Orbital Stability of the Transiting Planetary System HAT-P-25

NASA Astrophysics Data System (ADS)

Wang, Xian-Yu; Wang, Songhu; Hinse, Tobias C.; Li, Kai; Wang, Yong-Hao; Laughlin, Gregory; Liu, Hui-Gen; Zhang, Hui; Wu, Zhen-Yu; Zhou, Xu; Zhou, Ji-Lin; Hu, Shao-Ming; Wu, Dong-Hong; Peng, Xi-Yan; Chen, Yuan-Yuan

2018-06-01

We present eight new light curves of the transiting extra-solar planet HAT-P-25b obtained from 2013 to 2016 with three telescopes at two observatories. We use the new light curves, along with recent literature material, to estimate the physical and orbital parameters of the transiting planet. Specifically, we determine the mid-transit times (T C ) and update the linear ephemeris, T C[0] = 2456418.80996 ± 0.00025 [BJDTDB] and P = 3.65281572 ± 0.00000095 days. We carry out a search for transit timing variations (TTVs), and find no significant TTV signal at the ΔT = 80 s-level, placing a limit on the possible strength of planet–planet interactions (TTVG). In the course of our analysis, we calculate the upper mass-limits of the potential nearby perturbers. Near the 1:2, 2:1, and 3:1 resonances with HAT-P-25b, perturbers with masses greater than 0.5, 0.3, and 0.5 M ⊕ respectively, can be excluded. Furthermore, based on the analysis of TTVs caused by light travel time effect (LTTE) we also eliminate the possibility that a long-period perturber exists with M p > 3000 MJ within a = 11.2 au of the parent star.

Theoretical Study of the Jahn-Teller effect in CH3CN+ (X2E) and CD3CN+ (X2E): multimode spin-vibronic energy level calculations.

PubMed

Zhang, Shiyang; Mo, Yuxiang

2009-10-15

The spin-vibronic energy levels for CH(3)CN(+)(X(2)E) and CD(3)CN(+)(X(2)E) have been calculated using a diabatic model including multimode vibronic couplings and spin-orbit interaction without adjusting any parameter. The diabatic potential energy surfaces are represented by the Taylor expansions including linear, quadratic and bilinear vibronic coupling terms. The normal coordinates used in the Taylor expansion were expressed by the mass-weighted Cartesian coordinates. The adiabatic potential energy surfaces for CH(3)CN(+) and CD(3)CN(+) were calculated at the level of CASPT2/cc-pvtz, and the spin-orbit coupling constant was calculated at the level of MRCI/CAS/cc-pvtz. The spin-orbit energy splittings for the ground vibrational states of CH(3)CN(+)(X(2)E) and CD(3)CN(+)(X(2)E) are 20 and 16 cm(-1), respectively, which are resulted from the quenching of the spin-orbit coupling strength of 51 cm(-1). The calculated spin-vibronic levels are in good agreement with the experimental data. The calculation results show that the Jahn-Teller effects in CH(3)CN(+)(X(2)E) and CD(3)CN(+)(X(2)E) are essential to understand their spin-vibronic energy structure.

High-pressure insulator-to-metal transition in Sr3Ir2O7 studied by x-ray absorption spectroscopy

NASA Astrophysics Data System (ADS)

Donnerer, C.; Sala, M. Moretti; Pascarelli, S.; Rosa, A. D.; Andreev, S. N.; Mazurenko, V. V.; Irifune, T.; Hunter, E. C.; Perry, R. S.; McMorrow, D. F.

2018-01-01

High-pressure x-ray absorption spectroscopy was performed at the Ir L3 and L2 absorption edges of Sr3Ir2O7 . The branching ratio of white-line intensities continuously decreases with pressure, reflecting a reduction in the angular part of the expectation value of the spin-orbit coupling operator, 〈L .S 〉 . Up to the high-pressure structural transition at 53 GPa, this behavior can be explained within a single-ion model, where pressure increases the strength of the cubic crystal field, which suppresses the spin-orbit induced hybridization of Jeff=3 /2 and eg levels. We observe a further reduction of the branching ratio above the structural transition, which cannot be explained within a single-ion model of spin-orbit coupling and cubic crystal fields. This change in 〈L .S 〉 in the high-pressure, metallic phase of Sr3Ir2O7 could arise from noncubic crystal fields or a bandwidth-driven hybridization of Jeff=1 /2 ,3 /2 states and suggests that the electronic ground state significantly deviates from the Jeff=1 /2 limit.

High-pressure phase transitions of Fe 3-xTi xO 4 solid solution up to 60 GPa correlated with electronic spin transition

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

Yamanaka, Takamitsu; Kyono, Atsushi; Nakamoto, Yuki

2013-06-12

The structural phase transition of the titanomagnetite (Fe 3–xTi xO 4) solid solution under pressures up to 60 GPa has been clarified by single-crystal and powder diffraction studies using synchrotron radiation and a diamond-anvil cell. Present Rietveld structure refinements of the solid solution prove that the prefered cation distribution is based on the crystal field preference rather than the magnetic spin ordering in the solid solution. The Ti-rich phases in 0.734 ≤ x ≤1.0 undergo a phase transformation from the cubic spinel of Fd3m to the tetragonal spinel structure of I4 1/amd with c/a < 1.0. The transition is drivenmore » by a Jahn-Teller effect of IVFe 2+ (3d 6) on the tetrahedral site. The c/a < 1 ratio is induced by lifting of the degeneracy of the e orbitals by raising the d x2-y2 orbital below the energy of the d z2 orbital. The distortion characterized by c/a < 1 is more pronounced with increasing Ti content in the Fe 3–xTi xO 4 solid solutions and with increasing pressure. An X-ray emission experiment of Fe 2TiO 4 at high pressures confirms the spin transition of FeKβ from high spin to intermediate spin (IS) state. The high spin (HS)-to-low spin (LS) transition starts at 14 GPa and the IS state gradually increases with compression. The VIFe 2+ in the octahedral site is more prone for the HS-to-LS transition, compared with Fe 2+ in the fourfold- or eightfold-coordinated site. The transition to the orthorhombic post-spinel structure with space group Cmcm has been confirmed in the whole compositional range of Fe 3–xTi xO 4. The transition pressure decreases from 25 GPa (x = 0.0) to 15 GPa (x = 1.0) with increasing Ti content. There are two cation sites in the orthorhombic phase: M1 and M2 sites of eightfold and sixfold coordination, respectively. Fe 2+ and Ti 4+ are disordered on the M2 site. This structural change is accelerated at higher pressures due to the spin transition of Fe 2+ in the octahedral site. This is because the ionic radius

77 FR 5252 - Federal Travel Regulation; GSA E-Gov Travel Service (ETS) Transition to E-Gov Travel Service 2...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-02

... Travel Regulation; GSA E-Gov Travel Service (ETS) Transition to E-Gov Travel Service 2 (ETS2) AGENCY... (QMC), at [email protected]gov or (703) 605-2151. SUPPLEMENTARY INFORMATION: The Federal Travel...-GOV TRAVEL SERVICE GSA Bulletin ETS 12-01 TO: Heads of Federal Agencies SUBJECT: GSA E-Gov Travel...

Measurement of the ϕ → π0e+e- transition form factor with the KLOE detector

NASA Astrophysics Data System (ADS)

Anastasi, A.; Babusci, D.; Bencivenni, G.; Berlowski, M.; Bloise, C.; Bossi, F.; Branchini, P.; Budano, A.; Caldeira Balkeståhl, L.; Cao, B.; Ceradini, F.; Ciambrone, P.; Curciarello, F.; Czerwiński, E.; D'Agostini, G.; Danè, E.; De Leo, V.; De Lucia, E.; De Santis, A.; De Simone, P.; Di Cicco, A.; Di Domenico, A.; Di Salvo, R.; Domenici, D.; D'Uffizi, A.; Fantini, A.; Felici, G.; Fiore, S.; Gajos, A.; Gauzzi, P.; Giardina, G.; Giovannella, S.; Graziani, E.; Happacher, F.; Heijkenskjöld, L.; Ikegami Andersson, W.; Johansson, T.; Kamińska, D.; Krzemien, W.; Kupsc, A.; Loffredo, S.; Mandaglio, G.; Martini, M.; Mascolo, M.; Messi, R.; Miscetti, S.; Morello, G.; Moricciani, D.; Moskal, P.; Papenbrock, M.; Passeri, A.; Patera, V.; Perez del Rio, E.; Ranieri, A.; Salabura, P.; Santangelo, P.; Sarra, I.; Schioppa, M.; Silarski, M.; Sirghi, F.; Tortora, L.; Venanzoni, G.; Wiślicki, W.; Wolke, M.

2016-06-01

A measurement of the vector to pseudoscalar conversion decay ϕ →π0e+e- with the KLOE experiment is presented. A sample of ˜9500 signal events was selected from a data set of 1.7 fb-1 of e+e- collisions at √{ s} ˜mϕ collected at the DAΦNE e+e- collider. These events were used to perform the first measurement of the transition form factor |Fϕπ0 (q2) | and a new measurement of the branching ratio of the decay: BR (ϕ →π0e+e-) = (1.35 ±0.05-0.10+0.05) ×10-5. The result improves significantly on previous measurements and is in agreement with theoretical predictions.

Electronic excitation of carbonyl sulphide (COS) by high-resolution vacuum ultraviolet photoabsorption and electron-impact spectroscopy in the energy region from 4 to 11 eV

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

Limão-Vieira, P., E-mail: plimaovieira@fct.unl.pt; Department of Physics, Sophia University, Tokyo 102-8554; Department of Physical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA

2015-02-14

The electronic state spectroscopy of carbonyl sulphide, COS, has been investigated using high resolution vacuum ultraviolet photoabsorption spectroscopy and electron energy loss spectroscopy in the energy range of 4.0–10.8 eV. The spectrum reveals several new features not previously reported in the literature. Vibronic structure has been observed, notably in the low energy absorption dipole forbidden band assigned to the (4π←3π) ({sup 1}Δ←{sup 1}Σ{sup +}) transition, with a new weak transition assigned to ({sup 1}Σ{sup −}←{sup 1}Σ{sup +}) reported here for the first time. The absolute optical oscillator strengths are determined for ground state to {sup 1}Σ{sup +} and {sup 1}Πmore » transitions. Based on our recent measurements of differential cross sections for the optically allowed ({sup 1}Σ{sup +} and {sup 1}Π) transitions of COS by electron impact, the optical oscillator strength f{sub 0} value and integral cross sections (ICSs) are derived by applying a generalized oscillator strength analysis. Subsequently, ICSs predicted by the scaling are confirmed down to 60 eV in the intermediate energy region. The measured absolute photoabsorption cross sections have been used to calculate the photolysis lifetime of carbonyl sulphide in the upper stratosphere (20–50 km)« less

Cholesteric pitch transitions induced by mechanical strain.

PubMed

Lelidis, I; Barbero, G; Alexe-Ionescu, A L

2013-02-01

We investigate thickness and surface anchoring strength influence on pitch transitions in a planar cholesteric liquid crystal layer. The cholesteric-nematic transition is also investigated. We assume planar boundary conditions, with strong anchoring strength at one interface and weak anchoring strength at the other. The surface anchoring energy we consider to describe the deviation of the surface twist angle from the easy axis induced by a bulk deformation is a parabolic potential or Rapini and Papoular periodic potential, respectively. We show that under strain, all pitch transitions take place at a critical thickness that is equal to the quarter of the natural cholesteric pitch. The latter result does not depend on the anchoring strength, the particular surface potential, or material properties. The twist angle on the limiting surface characterized by weak anchoring varies with strain either by slipping and or in a discontinuous manner according to the thickness of the sample. The position of the bifurcation point depends only on the ratio of the extrapolation length over the layer thickness, but its value is model dependent. Multistability and multiplicity of the transition are discussed.

Does on-water resisted rowing increase or maintain lower-body strength?

PubMed

Lawton, Trent W; Cronin, John B; McGuigan, Michael R

2013-07-01

Over the past 30 years, endurance volumes have increased by >20% among the rowing elite; therefore, informed decisions about the value of weight training over other possible activities in periodized training plans for rowing need to be made. The purpose of this study was to quantify the changes in lower-body strength development after two 14-week phases of intensive resisted on-water rowing, either incorporating weight training or rowing alone. Ten elite women performed 2 resisted rowing ("towing ropes," e.g., 8 × 3 minutes) plus 6 endurance (e.g., 16-28 km at 70-80% maximum heart rate) and 2 rate-regulated races (e.g., 8,000 m at 24 strokes per minute) on-water each week. After a 4-week washout phase, the 14-week phase was repeated with the addition of 2 weight-training sessions (e.g., 3-4 sets × 6-15 reps). Percent (±SD) and standardized differences in effects (effect size [ES] ± 90% confidence limit) for 5-repetition leg pressing and isometric pulling strength were calculated from data ratio scaled for body mass, log transformed and adjusted for pretest scores. Resisted rowing alone did not increase leg pressing (-1.0 ± 5.3%, p = 0.51) or isometric pulling (5.3 ± 13.4%, p = 0.28) strength. In contrast, after weight training, a moderately greater increase in leg pressing strength was observed (ES = 0.72 ± 0.49, p = 0.03), although differences in isometric pulling strength were unclear (ES = 0.56 ± 1.69, p = 0.52). In conclusion, intensive on-water training including resisted rowing maintained but did not increase lower-body strength. Elite rowers or coaches might consider the incorporation of high-intensity nonfatiguing weight training concurrent to endurance exercise if increases in lower-body strength without changes in body mass are desired.

Superconductor-to-insulator transition and transport properties of underdoped YBa2Cu3O(y) crystals.

PubMed

Semba, K; Matsuda, A

2001-01-15

The carrier-concentration-driven superconductor-to-insulator (SI) transition as well as transport properties in underdoped YBa2Cu3O(y) twinned crystals is studied. The SI transition takes place at y approximately 6.3, carrier concentration n(SI)H approximately 3x10(20) cm(-3), anisotropy rho(c)/rho(ab) approximately 10(3), and the threshold resistivity rho(SI)ab approximately 0.8 mOmega cm which corresponds to a critical sheet resistance h/4e2 approximately 6.5 kOmega per CuO2 bilayer. The evolution of a carrier, nH infiniti y - 6.2, is clearly observed in the underdoped region. The resistivity and Hall coefficient abruptly acquire strong temperature dependence at y approximately 6.5 indicating a radical change in the electronic state.

Molecular-orbital model for metal-sapphire interfacial strength

NASA Technical Reports Server (NTRS)

Johnson, K. H.; Pepper, S. V.

1982-01-01

Self-consistent-field X-Alpha scattered-wave cluster molecular-orbital models have been constructed for transition and noble metals (Fe, Ni, Cu, and Ag) in contact with a sapphire (Al2O3) surface. It is found that a chemical bond is established between the metal d-orbital electrons and the nonbonding 2p-orbital electrons of the oxygen anions on the Al2O3 surface. An increasing number of occupied metal-sapphire antibonding molecular orbitals explains qualitatively the observed decrease of contact shear strength through the series Fe, Ni, Cu, and Ag.

Science with the space-based interferometer eLISA. II: gravitational waves from cosmological phase transitions

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

Caprini, Chiara, E-mail: chiara.caprini@cea.fr; Hindmarsh, Mark; Huber, Stephan

We investigate the potential for the eLISA space-based interferometer to detect the stochastic gravitational wave background produced by strong first-order cosmological phase transitions. We discuss the resulting contributions from bubble collisions, magnetohydrodynamic turbulence, and sound waves to the stochastic background, and estimate the total corresponding signal predicted in gravitational waves. The projected sensitivity of eLISA to cosmological phase transitions is computed in a model-independent way for various detector designs and configurations. By applying these results to several specific models, we demonstrate that eLISA is able to probe many well-motivated scenarios beyond the Standard Model of particle physics predicting strong first-ordermore » cosmological phase transitions in the early Universe.« less

Changes in muscle strength in individuals with statin-induced myopathy: A summary of 3 investigations.

PubMed

Panza, Gregory A; Taylor, Beth A; Dada, Marcin R; Thompson, Paul D

2015-01-01

There are inconsistent findings regarding muscular weakness in individuals with statin-induced myalgia. We used rigorous muscle testing to compare findings from 3 investigations in 3 different study populations to determine if statin myalgia is associated with measurable weakness. In all 3 studies, we measured maximal isometric handgrip strength, resting respiratory exchange ratio (RER), and knee extensor isometric and isokinetic force. In 2 of the 3 studies, elbow flexor isometric and isokinetic force and knee endurance fatigue index were also assessed. Knee extensor and elbow flexor measurements were obtained using an isokinetic dynamometer. Resting RER was measured using a metabolic breath-by-breath collection method. Measurement outcomes were compared on vs off drug. In study 1, 18 participants fit the criteria for statin myalgia. Participants taking atorvastatin 80 mg daily had significantly lower muscle strength in 5 (P < .05) of 14 measured variables. Participants on placebo (N = 10) with myalgia had significantly lower muscle strength in 4 (P < .05) of 14 measured variables. In study 2, 18 participants tested positive for statin-induced myalgia when receiving simvastatin 20 mg daily and displayed no significant muscle strength changes (all P > .05). In study 3, 11 patients with statin-induced myalgia completed the study and had a significant decrease in 2 (P < .05) of 10 leg muscle strength variables. In all 3 studies, no significant changes were shown for handgrip strength or RER (all P > .05). Our results indicate that after a short-term treatment with statin therapy, a rigorous muscle strength protocol does not show decrements of muscle strength in subjects with statin myalgia. Short-term treatment with statin therapy is not common in clinical practice. Thus, future studies should examine the effects of prolonged statin therapy on muscle strength. Published by Elsevier Inc.

Pairing transition, coherence transition, and the irreversibility line in granular GdBa2Cu3O7-δ

NASA Astrophysics Data System (ADS)

Roa-Rojas, J.; Menegotto Costa, R.; Pureur, P.; Prieto, P.

2000-05-01

We report on electrical magnetoconductivity experiments near the superconducting transition of a granular sample of GdBa2Cu3O7-δ. The measurements were performed in magnetic fields ranging from 0 to 500 Oe applied parallel to the current orientation. The results show that the transition proceeds in two steps. When the temperature is decreased we first observe the pairing transition, which stabilizes superconductivity within the grains at a temperature practically coincident with the bulk critical temperature Tc. Analysis of the fluctuation contributions to the conductivity shows that the universality class for this transition is that of the three dimensional (3D)-XY model in the ordered case, with dynamic critical exponent z=3/2. Close to the zero-resistance state, the measurements reveal the occurrence of a coherence transition, where the phases of the order parameter in individual grains become long-range ordered. The critical temperature Tco for this transition is close to the point where the resistivity vanishes. A strong enlargement of the fluctuation interval preceding the coherence transition is caused by the applied magnetic field. In this region, a 3D-Gaussian regime and an asymptotic critical regime were clearly identified. The critical conductivity behavior for the coherence transition is interpreted within a 3D-XY model where disorder and frustration are relevant. The irreversibility line is determined from magnetoconductivity measurements performed according to the zero-field-cooled (ZFC) and field-cooled data collected on cooling (FCC) recipes. The locus of this line coincides with the upper temperature limit for the fluctuation region above the coherence transition. The irreversibility line is interpreted as an effect of the formation of small clusters with closed loops of Josephson-coupled grains.

Dithieno[3,2-c:2',3'-e]-2,7-diketophosphepin: a unique building block for multifunctional π-conjugated materials.

PubMed

He, Xiaoming; Borau-Garcia, Javier; Woo, Alva Y Y; Trudel, Simon; Baumgartner, Thomas

2013-01-23

A series of conjugated materials based on the new dithieno[3,2-c:2',3'-e]-2,7-diketophosphepin (DTDKP) building block have been studied for the first time. Theoretical calculations predict DTDKP to be a better electron acceptor than the well-known dithienophosphole and the nitrogen analogue, bithiopheneimide. Cyclic voltammetry studies revealed two reduction processes that support their promising electron-acceptor properties, and modification of the P center with O or gold(I) further reduced the LUMO energy to ca. -3.6 eV. Expansion of the DTDKP core with various aromatic moieties has been realized using the Huisgen alkynyl click reaction, resulting in altered optical and electrochemical properties with compounds showing a high-energy absorption band at ca. 270-290 nm and a low-energy band at ca. 390-460 nm. The acceptor character of the DTDKP core was demonstrated by a red shift following the electron-donating strength of the appended aromatic moiety. Intriguing white-light emission from just a single species with the CIE coordinates of (0.33, 0.34) was observed for some of the extended species as the result of an unexpected dual-emission behavior. The high-energy emission in the blue-to-green region and the low-energy emission in the orange-to-red region are attributed to a π* → π transition of the DTDKP core and charge transfer from the triazole moiety to DTDKP, respectively. Apart from tuning of the molecular properties, this novel building block has also been applied in a self-assembled organogel, which exhibited pronounced luminescence. Scanning electron microscopy confirmed that the gel self-assembled by forming a network of entangled 1D fibrous structures on the micrometer scale.

Reactive Strength Index: A Poor Indicator of Reactive Strength?

PubMed

Healy, Robin; Kenny, Ian; Harrison, Drew

2017-11-28

The primary aim was to assess the relationships between reactive strength measures and associated kinematic and kinetic performance variables achieved during drop jumps. A secondary aim was to highlight issues with the use of reactive strength measures as performance indicators. Twenty eight national and international level sprinters, consisting of fourteen men and women, participated in this cross-sectional analysis. Athletes performed drop jumps from a 0.3 m box onto a force platform with dependent variables contact time (CT), landing time (TLand), push-off time (TPush), flight time (FT), jump height (JH), reactive strength index (RSI, calculated as JH / CT), reactive strength ratio (RSR, calculated as FT / CT) and vertical leg spring stiffness (Kvert) recorded. Pearson's correlation test found very high to near perfect relationships between RSI and RSR (r = 0.91 to 0.97), with mixed relationships found between RSI, RSR and the key performance variables, (Men: r = -0.86 to -0.71 between RSI/RSR and CT, r = 0.80 to 0.92 between RSI/RSR and JH; Women: r = -0.85 to -0.56 between RSR and CT, r = 0.71 between RSI and JH). This study demonstrates that the method of assessing reactive strength (RSI versus RSR) may be influenced by the performance strategies adopted i.e. whether an athlete achieves their best reactive strength scores via low CTs, high JHs or a combination. Coaches are advised to limit the variability in performance strategies by implementing upper and / or lower CT thresholds to accurately compare performances between individuals.

Ageing kinetics and strength of airborne-particle abraded 3Y-TZP ceramics.

PubMed

Cotič, Jasna; Jevnikar, Peter; Kocjan, Andraž

2017-07-01

The combined effects of alumina airborne-particle abrasion and prolonged in vitro ageing on the flexural strength of 3Y-TZP ceramic have been studied. The aim was to identify the different effects on the surface and subsurface regions that govern the performance of this popular bioceramic known for its susceptibility to low-temperature degradation (LTD). As-sintered or airborne-particle abraded 3Y-TZP discs were subjected to ageing at 134°C for up to 480h. Biaxial flexural strength was measured and the relative amount of monoclinic phase determined using X-ray diffraction. The transformed zone depth (TZD) was observed on cross-sections with scanning electron microscopy coupled with a focused ion beam. Segmented linear regression was used to analyze the flexural strength and TZD as functions of the ageing time. A two-step linear ageing kinetics was detected in airborne-particle abraded specimens, reflecting the different microstructures through which the LTD proceeds into the bulk. A 10μm thick altered zone under the abraded surface was involved in both the surface strengthening and the increased ageing resistance. When the zone was annihilated by the LTD, the strength of the ceramic specimens and the speed of LTD returned to the values measured before abrasion. Even at prolonged ageing times, the strength of abraded groups was not lower than that of as-sintered groups. Both the ageing kinetics and the flexural strength were prominently affected by airborne-particle abrasion, which altered the subsurface microstructure and phase composition. Airborne-particle abrasion was not harmful to the 3Y-TZP ceramics' stability. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Lost mold-rapid infiltration forming: Strength control in mesoscale 3Y-TZP ceramics

NASA Astrophysics Data System (ADS)

Antolino, Nicholas E.

The strength of nanoparticulate enabled microdevices and components is directly related to the interfacial control between particles and the flaws introduced as these particles come together to form the device or component. One new application for micro-scale or meso-scale (10's microm to 100's microm) devices is surgical instruments designed to enter the body, perform a host of surgeries within the body cavity, and be extracted with no external incisions to the patient. This new concept in surgery, called natural orifice transluminal endoscopic surgery (NOTES), requires smaller and more functional surgical tools. Conventional processing routes do not exist for making these instruments with the desired size, topology, precision, and strength. A process, called lost mold-rapid infiltration forming (LM-RIF), was developed to satisfy this need. A tetragonally stabilized zirconia polycrystalline material (3Y-TZP) is a candidate material for this process and application because of its high strength, chemical stability, high elastic modulus, and reasonably high toughness for a ceramic. Modern technical ceramics, like Y-TZP, are predicated on dense, fine grained microstructures and functional mesoscale devices must also adhere to this standard. Colloid and interfacial chemistry was used to disperse and concentrate the Y-TZP nanoparticles through a very steep, yet localized, potential energy barrier against the van der Waals attractive force. The interparticle interaction energies were modeled and compared to rheological data on the suspension. At high concentrations, the suspension was pseudoplastic, which is evidence that a structure was formed within the suspension that could be disrupted by a shearing force. The LM-RIF process exploits this rheological behavior to fill mold cavities created by photolithography. The premise of the LM-RIF process is to process the particulate material into a dense ceramic body while the unsintered mesoscale parts are supported en masse

Modulus, strength and thermal exposure studies of FP-Al2O3/aluminum and FP-Al2O3/magnesium composites

NASA Technical Reports Server (NTRS)

Bhatt, R. T.

1981-01-01

The mechanical properties of FP-Al2O3 fiber reinforced composites prepared by liquid infiltration techniques are improved. A strengthening addition, magnesium, was incorporated with the aluminum-lithium matrix alloy usually selected for these composites because of its good wetting characteristics. This ternary composite, FP-Al2O3/Al-(2-3)Li-(3-5)Mg, showed improved transverse strength compared with FP-Al2O3/Al-(2-3)Li composites. The lower axial strengths found for the FP-Al2O3/Al-(2-3)Li-(3-5)Mg composites were attributed to fabrication related defects. Another technique was the use of Ti/B coated FP-Al2O3 fibers in the composites. This coating is readily wet by molten aluminum and permitted the use of more conventional aluminum alloys in the composites. However, the anticipated improvements in the axial and transverse strengths were not obtained due to poor bonding between the fiber coating and the matrix. A third approach studied to improve the strengths of FP-Al2O3 reinforced composites was the use of magnesium alloys as matrix materials. While these alloys wet fibers satisfactorily, the result indicated that the magnesium alloy composites used offered no axial strength or modulus advantage over FP-Al2O3/Al-(2-3)Li composites.

Evolution of E × B shear and coherent fluctuations prior to H-L transitions in DIII-D and control strategies for H-L transitions

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

Eldon, David; Boivin, Rejean L.; Chrystal, Colin

While operating a magnetic fusion device in H-mode has many advantages, care must be taken to understand and control the release of energy during the H-L back transition, as the extra energy stored within the H-mode transport barrier will have the potential to cause damage to material components of a large future tokamak such as ITER. Examining a scenario where the H-L back transition sequence begins before the E × B shearing layer decays on its own, we identify a long-lived precursor mode that is tied to the events of the H-L sequence and we develop a robust control strategymore » for ensuring gradual release of energy during the transition sequence. Back transitions in this scenario commonly begin with a rapid relaxation of the pedestal, which was previously shown to be inconsistent with ideal peeling-ballooning instability as the trigger, despite being otherwise similar to a large type-I Edge Localized Mode (ELM). Here, this so-called transient occurs when the E × B shearing rate ω E×B is significantly larger than the turbulence decorrelation rate ωT, indicating that this is not the result of runaway turbulence recovery. The transient is always synchronous with amplitude and propagation velocity modulations of the precursor mode, which has been dubbed the Modulating Pedestal Mode (MPM).The MPM is a coherent density fluctuation, which, in our scenario at least, reliably appears in the steep gradient region with f ≈ 70 kHz, k θ ≈ 0.3 cm –1, and it exists for ≳100 ms before the onset of back transitions. The transient may be reliably eliminated by reducing toroidal rotation in the co-current direction by the application of torque from counter-injecting neutral beams. The transient in these “soft” H-L transitions is then replaced by a small type-III ELM, which is also always synchronous with the MPM, and MPM shows the same behavior in both hard and soft cases.« less

Evolution of E × B shear and coherent fluctuations prior to H-L transitions in DIII-D and control strategies for H-L transitions

DOE PAGES

Eldon, David; Boivin, Rejean L.; Chrystal, Colin; ...

2015-11-19

While operating a magnetic fusion device in H-mode has many advantages, care must be taken to understand and control the release of energy during the H-L back transition, as the extra energy stored within the H-mode transport barrier will have the potential to cause damage to material components of a large future tokamak such as ITER. Examining a scenario where the H-L back transition sequence begins before the E × B shearing layer decays on its own, we identify a long-lived precursor mode that is tied to the events of the H-L sequence and we develop a robust control strategymore » for ensuring gradual release of energy during the transition sequence. Back transitions in this scenario commonly begin with a rapid relaxation of the pedestal, which was previously shown to be inconsistent with ideal peeling-ballooning instability as the trigger, despite being otherwise similar to a large type-I Edge Localized Mode (ELM). Here, this so-called transient occurs when the E × B shearing rate ω E×B is significantly larger than the turbulence decorrelation rate ωT, indicating that this is not the result of runaway turbulence recovery. The transient is always synchronous with amplitude and propagation velocity modulations of the precursor mode, which has been dubbed the Modulating Pedestal Mode (MPM).The MPM is a coherent density fluctuation, which, in our scenario at least, reliably appears in the steep gradient region with f ≈ 70 kHz, k θ ≈ 0.3 cm –1, and it exists for ≳100 ms before the onset of back transitions. The transient may be reliably eliminated by reducing toroidal rotation in the co-current direction by the application of torque from counter-injecting neutral beams. The transient in these “soft” H-L transitions is then replaced by a small type-III ELM, which is also always synchronous with the MPM, and MPM shows the same behavior in both hard and soft cases.« less

Biaxial flexural strength of CAD/CAM ceramics.

PubMed

Buso, L; Oliveira-Júnior, O B; Hiroshi Fujiy, F; Leão Lombardo, G H; Ramalho Sarmento, H; Campos, F; Assunção Souza, R O

2011-06-01

Aim of the study was to evaluate the biaxial flexural strength of ceramics processed using the Cerec inLab system. The hypothesis was that the flexural strength would be influenced by the type of ceramic. Ten samples (ISO 6872) of each ceramic (N.=50/n.=10) were made using Cerec inLab (software Cerec 3D) (Ø:15 mm, thickness: 1.2 mm). Three silica-based ceramics (Vita Mark II [VM], ProCad [PC] and e-max CAD ECAD]) and two yttria-stabilized tetragonal-zirconia-polycrystalline ceramics (Y-TZP) (e-max ZirCad [ZrCAD] and Vita In-Ceram 2000 YZ Cubes [VYZ]) were tested. The samples were finished with wet silicone carbide papers up to 1 200-grit and polished in a polishing machine with diamond paste (3 µm). The samples were then submitted to biaxial flexural strength testing in a universal testing machine (EMIC), 1 mm/min. The data (MPa) were analyzed using the Kruskal-Wallis and Dunn (5%) tests. Scanning electronic microscopy (SEM) was performed on a representative sample from each group. The values (median, mean±sd) obtained for the experimental groups were: VM (101.7, 102.1±13.65 MPa), PC (165.2, 160±34.7 MPa), ECAD (437.2, 416.1±50.1 MPa), ZrCAD (804.2, 800.8±64.47 MPa) and VYZ (792.7, 807±100.7 MPa). The type of ceramic influenced the flexural strength values (P=0.0001). The ceramics ECADa, e-max ZrCADa and VYZa presented similar flexural strength values which were significantly higher than the other groups (PCb and VM IIb), which were similar statistically between them (Dunn's test). The hypothesis was accepted. The polycrystalline ceramics (Y-TZP) should be material chosen for make FPDs because of their higher flexural strength values.

Continuous Easy-Plane Deconfined Phase Transition on the Kagome Lattice

NASA Astrophysics Data System (ADS)

Zhang, Xue-Feng; He, Yin-Chen; Eggert, Sebastian; Moessner, Roderich; Pollmann, Frank

2018-03-01

We use large scale quantum Monte Carlo simulations to study an extended Hubbard model of hard core bosons on the kagome lattice. In the limit of strong nearest-neighbor interactions at 1 /3 filling, the interplay between frustration and quantum fluctuations leads to a valence bond solid ground state. The system undergoes a quantum phase transition to a superfluid phase as the interaction strength is decreased. It is still under debate whether the transition is weakly first order or represents an unconventional continuous phase transition. We present a theory in terms of an easy plane noncompact C P1 gauge theory describing the phase transition at 1 /3 filling. Utilizing large scale quantum Monte Carlo simulations with parallel tempering in the canonical ensemble up to 15552 spins, we provide evidence that the phase transition is continuous at exactly 1 /3 filling. A careful finite size scaling analysis reveals an unconventional scaling behavior hinting at deconfined quantum criticality.

Current-driven orbital order-disorder transition in LaMnO3

NASA Astrophysics Data System (ADS)

Mondal, Parthasarathi; Bhattacharya, Dipten; Mandal, P.

2011-08-01

We report a significant influence of electric current on the orbital order-disorder transition in LaMnO3. The transition temperature TOO, thermal hysteresis in the resistivity ρ versus temperature T plot around TOO, and latent heat L associated with the transition decrease with an increase in current density. Eventually, at a critical current density, L reaches zero. The transition zone, on the other hand, broadens with an increase in current density. The states at ordered, disordered, and transition zones are all found to be stable within the time window from ˜10-3 to ˜104 s.

Benchmarking transition energies and emission strengths for X-ray astrophysics with measurements at the Livermore EBITs

NASA Astrophysics Data System (ADS)

Hell, Natalie

2017-03-01

measured the energies of K α transitions in L-shell ions of Si and S at EBIT using the EBIT calorimeter spectrometer (ECS) with 4.5-5.0 eV resolution, i.e., a similar resolution to the Astro-H /Hitomi SXS soft X-ray spectrometer. While these lines will become interesting also for L-shell ions of other astrophysically abundant elements, they have been observed most prominently from L-shell ions of Si and S in the X-ray spectra of a variety of astrophysical sources. The measured line centers have an accuracy of 0.5 eV for the strong transitions and 1 eV for the weaker ones. This accuracy translates to Doppler shifts of less than 90 km s -1 , i.e., less than the calibration uncertainty of the Chandra high-energy transmission gratings. The measured line centers are identified with my own calculations with the Flexible Atomic Code (FAC) and compared to these and calculations by Palmeri et al. (2008). I demonstrate the impact of these measurements by re-evaluating Doppler shifts for the high-mass X-ray binaries Vela X-1 and Cyg X-1 with the new reference data. Using the high-resolution, imaging focusing spherical crystal spectrometer EBHiX with a quartz 101 crystal, I verified the results from the ECS measurements on K α transitions in N- through Li-like S. The measurement has a spectral resolution of better than 0.52 eV. The derived transition energies have an accuracy of 0.2 eV, corresponding to Doppler shifts of < 30 km s -1 , i.e., within the requirements set by the planned Athena X-ray observatory. Secondly, I used the EBHiX crystal spectrometer with a quartz 110 crystal in second order to measure the strongly blended K α spectra of M-shell Fe ions around 6.4 keV. Contributions to the 6.4 keV line complex from these ions are important for transient plasmas such as those in supernova remnants. While a simple FAC model of Cl- through F-like Fe suggested it should be possible to resolve major contributions from different charge states to this complex at a 2 eV resolution

Acoustic waves and the detectability of first-order phase transitions by eLISA

NASA Astrophysics Data System (ADS)

Weir, David J.

2017-05-01

In various extensions of the Standard Model it is possible that the electroweak phase transition was first order. This would have been a violent process, involving the formation of bubbles and associated shock waves. Not only would the collision of these bubbles and shock waves be a detectable source of gravitational waves, but persistent acoustic waves could enhance the signal and improve prospects of detection by eLISA. I summarise the results of a recent campaign to model such a phase transition based on large-scale hydrodynamical simulations, and its implications for the eLISA mission.

[3 Tesla MRI: successful results with higher field strengths].

PubMed

Schmitt, F; Grosu, D; Mohr, C; Purdy, D; Salem, K; Scott, K T; Stoeckel, B

2004-01-01

The recent development of 3 Tesla MRI (3T MRI) has been fueled by promise of increased signal-to-noise ratio(SNR). Many are excited about the opportunity to not only use the increased SNR for clearer images, but also the chance to exchange it for better resolution or faster scans. These possibilities have caused a rapid increase in the market for 3T MRI, where the faster scanning tips an already advantageous economic outlook in favor of the user. As a result, the global market for 3T has grown from a research only market just a few years ago to an ever-increasing clinically oriented customer base. There are, however, significant obstacles to 3T MRI presented by the physics at higher field strengths. For example, the T1 relaxation times are prolonged with increasing magnet field strength. Further, the increased RF-energy deposition (SAR), the larger the chemical shift and the stronger susceptibility effect have to be considered as challenges. It is critical that one looks at both the advantages and disadvantages of using 3T. While there are many issues to address aand a number of different methods for doing so, to properly tackle each of these concerns will take time and effort on the part od researchers and clinicians. The optimization of 3T MRI scanning will have to be a combined effort, though much of the work to date has been in neuroimaging. Multiple applications have been explored in addition to clinical anatomical imaging, where resolution is improved showing structure in the brain never seen before in human MRI. Body and cardiac imaging provide a great challenge but are also achievable at 3T. As an example, the full range of clinical applications currently achieved on today's state-of-the-art 1.5T cardiac MR scanners has also been demonstrated at 3T. In the body, the full range of contrast is available over large fields of view allowing whole liver studies in the clinic or, as needed, one may choose a smaller field of view for high-resolution imaging of the

Are only Emotional Strengths Emotional? Character Strengths and Disposition to Positive Emotions.

PubMed

Güsewell, Angelika; Ruch, Willibald

2012-07-01

This study aimed to examine the relations between character strengths and dispositional positive emotions (i.e. joy, contentment, pride, love, compassion, amusement, and awe). A sample of 574 German-speaking adults filled in the Dispositional Positive Emotion Scales (DPES; Shiota, Keltner, & John, 2006), and the Values in Action Inventory of Strengths (VIA-IS; Peterson, Park, & Seligman, 2005). The factorial structure of the DPES was examined on item level. Joy and contentment could not be clearly separated; the items of the other five emotions loaded on separate factors. A confirmatory factor analysis assuming two latent factors (self-oriented and object/situation specific) was computed on scale level. Results confirmed the existence of these factors, but also indicated that the seven emotions did not split up into two clearly separable families. Correlations between dispositional positive emotions and character strengths were positive and generally low to moderate; a few theoretically meaningful strengths-emotions pairs yielded coefficients>.40. Finally, the link between five character strengths factors (i.e. emotional strengths, interpersonal strengths, strengths of restraint, intellectual strengths, and theological strengths) and the emotional dispositions was examined. Each of the factors displayed a distinctive "emotional pattern"; emotional strengths evidenced the most numerous and strongest links to emotional dispositions. © 2012 The Authors. Applied Psychology: Health and Well-Being © 2012 The International Association of Applied Psychology.

Oscillator strengths and integral cross sections for the valence-shell excitations of nitric oxide studied by fast electron impact.

PubMed

Xu, Xin; Xu, Long-Quan; Xiong, Tao; Chen, Tao; Liu, Ya-Wei; Zhu, Lin-Fan

2018-01-28

The generalized oscillator strengths for the valence-shell excitations of A 2 Σ + , C 2 Π, and D 2 Σ + electronic-states of nitric oxide have been determined at an incident electron energy of 1500 eV with an energy resolution of 70 meV. The optical oscillator strengths for these transitions have been obtained by extrapolating the generalized oscillator strengths to the limit that the squared momentum transfer approaches to zero, which give an independent cross-check to the previous experimental and theoretical results. The integral cross sections for the valence-shell excitations of nitric oxide have been determined systematically from the threshold to 2500 eV with the aid of the newly developed BE-scaling method for the first time. The present optical oscillator strengths and integral cross sections of the valence-shell excitations of nitric oxide play an important role in understanding many physics and chemistry of the Earth's upper atmosphere such as the radiative cooling, ozone destruction, day glow, aurora, and so on.

Field-induced phase transitions and enhanced double negative electrocaloric effects in (Pb,La)(Zr,Sn,Ti)O3 antiferroelectric single crystal

NASA Astrophysics Data System (ADS)

Zhuo, Fangping; Li, Qiang; Qiao, Huimin; Yan, Qingfeng; Zhang, Yiling; Xi, Xiaoqing; Chu, Xiangcheng; Long, Xifa; Cao, Wenwu

2018-03-01

Field-induced phase transitions and electrocaloric effect have been studied in (Pb,La)(Zr,Sn,Ti)O3 (PLZST) antiferroelectric single crystal. Temperature dependent dielectric, Raman spectra, as well as in situ domain evolution demonstrated that the order of phase transitions during heating is in the sequence of orthorhombic antiferroelectric → tetragonal antiferroelectric → cubic paraelectric. Enhanced negative electrocaloric effect value of -3.6 °C and electrocaloric strength of 0.3 K mm/kV at 125 °C have been achieved. Double negative effects (-0.7 °C at 45 °C and -3.6 °C at 125 °C) and a relatively large positive effect (1 °C) near Curie temperature (190 °C) have been found in the PLZST single crystal. Moreover, microscopic dipoles and a phenomenological Landau-type model were employed to understand these unusual electrocaloric effects. Enhanced negative effect and the coexistence of both negative and positive effects in one material are promising for us to develop practical solid-state cooling devices with high efficiency.

Broadband dielectric response of CaCu3Ti4O12 : From dc to the electronic transition regime

NASA Astrophysics Data System (ADS)

Kant, Ch.; Rudolf, T.; Mayr, F.; Krohns, S.; Lunkenheimer, P.; Ebbinghaus, S. G.; Loidl, A.

2008-01-01

We report on phonon properties and electronic transitions in CaCu3Ti4O12 , a material which reveals a colossal dielectric constant at room temperature without any ferroelectric transition. The results of far- and midinfrared measurements are compared to those obtained by broadband dielectric and millimeter-wave spectroscopy on the same single crystal. The unusual temperature dependence of phonon eigenfrequencies, dampings, and ionic plasma frequencies of low-lying phonon modes is analyzed and discussed in detail. Electronic excitations below 4eV are identified as transitions between full and empty hybridized oxygen-copper bands and between oxygen-copper and unoccupied Ti3d bands. The unusually small band gap determined from the dc conductivity (˜200meV) compares well with the optical results.

Field-induced polarization rotation and phase transitions in 0.70 Pb (M g1 /3N b2 /3 ) O3-0.30 PbTi O3 piezoceramics observed by in situ high-energy x-ray scattering

NASA Astrophysics Data System (ADS)

Hou, Dong; Usher, Tedi-Marie; Fulanovic, Lovro; Vrabelj, Marko; Otonicar, Mojca; Ursic, Hana; Malic, Barbara; Levin, Igor; Jones, Jacob L.

2018-06-01

Changes to the crystal structure of 0.70 Pb (M g1 /3N b2 /3 ) O3-0.30 PbTi O3 (PMN-0.30PT) piezoceramic under application of electric fields at the long-range and local scale are revealed by in situ high-energy x-ray diffraction (XRD) and pair-distribution function (PDF) analyses, respectively. The crystal structure of unpoled samples is identified as monoclinic C m at both the long-range and local scale. In situ XRD results suggest that field-induced polarization rotation and phase transitions occur at specific field strengths. A polarization rotation pathway is proposed based on the Bragg-peak behaviors and the Le Bail fitting results of the in situ XRD patterns. The PDF results show systematic changes to the structures at the local scale, which is in agreement with the changes inferred from the in situ XRD study. More importantly, our results prove that polarization rotation can be detected and determined in a polycrystalline relaxor ferroelectric. This study supports the idea that multiple contributions, specifically ferroelectric-ferroelectric phase transition and polarization rotation, are responsible for the high piezoelectric properties at the morphotropic phase boundary of PMN-x PT piezoceramics.

Total edge irregularity strength of (n,t)-kite graph

NASA Astrophysics Data System (ADS)

Winarsih, Tri; Indriati, Diari

2018-04-01

Let G(V, E) be a simple, connected, and undirected graph with vertex set V and edge set E. A total k-labeling is a map that carries vertices and edges of a graph G into a set of positive integer labels {1, 2, …, k}. An edge irregular total k-labeling λ :V(G)\\cup E(G)\\to \\{1,2,\\ldots,k\\} of a graph G is a labeling of vertices and edges of G in such a way that for any different edges e and f, weights wt(e) and wt(f) are distinct. The weight wt(e) of an edge e = xy is the sum of the labels of vertices x and y and the label of the edge e. The total edge irregularity strength of G, tes(G), is defined as the minimum k for which a graph G has an edge irregular total k-labeling. An (n, t)-kite graph consist of a cycle of length n with a t-edge path (the tail) attached to one vertex of a cycle. In this paper, we investigate the total edge irregularity strength of the (n, t)-kite graph, with n > 3 and t > 1. We obtain the total edge irregularity strength of the (n, t)-kite graph is tes((n, t)-kite) = \\lceil \\frac{n+t+2}{3}\\rceil .

9 CFR 3.140 - Care in transit.

Code of Federal Regulations, 2014 CFR

2014-01-01

... Warmblooded Animals Other Than Dogs, Cats, Rabbits, Hamsters, Guinea Pigs, Nonhuman Primates, and Marine... 9 Animals and Animal Products 1 2014-01-01 2014-01-01 false Care in transit. 3.140 Section 3.140 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE ANIMAL...

9 CFR 3.116 - Care in transit.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 9 Animals and Animal Products 1 2013-01-01 2013-01-01 false Care in transit. 3.116 Section 3.116 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE ANIMAL WELFARE STANDARDS Specifications for the Humane Handling, Care, Treatment, and Transportation of Marine...

9 CFR 3.140 - Care in transit.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Warmblooded Animals Other Than Dogs, Cats, Rabbits, Hamsters, Guinea Pigs, Nonhuman Primates, and Marine... 9 Animals and Animal Products 1 2011-01-01 2011-01-01 false Care in transit. 3.140 Section 3.140 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE ANIMAL...

9 CFR 3.116 - Care in transit.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 9 Animals and Animal Products 1 2014-01-01 2014-01-01 false Care in transit. 3.116 Section 3.116 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE ANIMAL WELFARE STANDARDS Specifications for the Humane Handling, Care, Treatment, and Transportation of Marine...

9 CFR 3.140 - Care in transit.

Code of Federal Regulations, 2013 CFR

2013-01-01

... Warmblooded Animals Other Than Dogs, Cats, Rabbits, Hamsters, Guinea Pigs, Nonhuman Primates, and Marine... 9 Animals and Animal Products 1 2013-01-01 2013-01-01 false Care in transit. 3.140 Section 3.140 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE ANIMAL...

9 CFR 3.140 - Care in transit.

Code of Federal Regulations, 2012 CFR

2012-01-01

... Warmblooded Animals Other Than Dogs, Cats, Rabbits, Hamsters, Guinea Pigs, Nonhuman Primates, and Marine... 9 Animals and Animal Products 1 2012-01-01 2012-01-01 false Care in transit. 3.140 Section 3.140 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE ANIMAL...

9 CFR 3.116 - Care in transit.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 9 Animals and Animal Products 1 2012-01-01 2012-01-01 false Care in transit. 3.116 Section 3.116 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE ANIMAL WELFARE STANDARDS Specifications for the Humane Handling, Care, Treatment, and Transportation of Marine...

9 CFR 3.140 - Care in transit.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Warmblooded Animals Other Than Dogs, Cats, Rabbits, Hamsters, Guinea Pigs, Nonhuman Primates, and Marine... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Care in transit. 3.140 Section 3.140 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE ANIMAL...

Geometric structure and information change in phase transitions

NASA Astrophysics Data System (ADS)

Kim, Eun-jin; Hollerbach, Rainer

2017-06-01

We propose a toy model for a cyclic order-disorder transition and introduce a geometric methodology to understand stochastic processes involved in transitions. Specifically, our model consists of a pair of forward and backward processes (FPs and BPs) for the emergence and disappearance of a structure in a stochastic environment. We calculate time-dependent probability density functions (PDFs) and the information length L , which is the total number of different states that a system undergoes during the transition. Time-dependent PDFs during transient relaxation exhibit strikingly different behavior in FPs and BPs. In particular, FPs driven by instability undergo the broadening of the PDF with a large increase in fluctuations before the transition to the ordered state accompanied by narrowing the PDF width. During this stage, we identify an interesting geodesic solution accompanied by the self-regulation between the growth and nonlinear damping where the time scale τ of information change is constant in time, independent of the strength of the stochastic noise. In comparison, BPs are mainly driven by the macroscopic motion due to the movement of the PDF peak. The total information length L between initial and final states is much larger in BPs than in FPs, increasing linearly with the deviation γ of a control parameter from the critical state in BPs while increasing logarithmically with γ in FPs. L scales as |lnD | and D-1 /2 in FPs and BPs, respectively, where D measures the strength of the stochastic forcing. These differing scalings with γ and D suggest a great utility of L in capturing different underlying processes, specifically, diffusion vs advection in phase transition by geometry. We discuss physical origins of these scalings and comment on implications of our results for bistable systems undergoing repeated order-disorder transitions (e.g., fitness).

Geometric structure and information change in phase transitions.

PubMed

Kim, Eun-Jin; Hollerbach, Rainer

2017-06-01

We propose a toy model for a cyclic order-disorder transition and introduce a geometric methodology to understand stochastic processes involved in transitions. Specifically, our model consists of a pair of forward and backward processes (FPs and BPs) for the emergence and disappearance of a structure in a stochastic environment. We calculate time-dependent probability density functions (PDFs) and the information length L, which is the total number of different states that a system undergoes during the transition. Time-dependent PDFs during transient relaxation exhibit strikingly different behavior in FPs and BPs. In particular, FPs driven by instability undergo the broadening of the PDF with a large increase in fluctuations before the transition to the ordered state accompanied by narrowing the PDF width. During this stage, we identify an interesting geodesic solution accompanied by the self-regulation between the growth and nonlinear damping where the time scale τ of information change is constant in time, independent of the strength of the stochastic noise. In comparison, BPs are mainly driven by the macroscopic motion due to the movement of the PDF peak. The total information length L between initial and final states is much larger in BPs than in FPs, increasing linearly with the deviation γ of a control parameter from the critical state in BPs while increasing logarithmically with γ in FPs. L scales as |lnD| and D^{-1/2} in FPs and BPs, respectively, where D measures the strength of the stochastic forcing. These differing scalings with γ and D suggest a great utility of L in capturing different underlying processes, specifically, diffusion vs advection in phase transition by geometry. We discuss physical origins of these scalings and comment on implications of our results for bistable systems undergoing repeated order-disorder transitions (e.g., fitness).

Tight regulation of a timed nuclear import wave of EKLF by PKCθ and FOE during Pro-E to Baso-E transition.

PubMed

Shyu, Yu-Chiau; Lee, Tung-Liang; Chen, Xin; Hsu, Pang-Hung; Wen, Shau-Ching; Liaw, Yi-Wei; Lu, Chi-Huan; Hsu, Po-Yen; Lu, Mu-Jie; Hwang, JauLang; Tsai, Ming-Daw; Hwang, Ming-Jing; Chen, Jim-Ray; Shen, Che-Kun James

2014-02-24

Erythropoiesis is a highly regulated process during which BFU-E are differentiated into RBCs through CFU-E, Pro-E, PolyCh-E, OrthoCh-E, and reticulocyte stages. Uniquely, most erythroid-specific genes are activated during the Pro-E to Baso-E transition. We show that a wave of nuclear import of the erythroid-specific transcription factor EKLF occurs during the Pro-E to Baso-E transition. We further demonstrate that this wave results from a series of finely tuned events, including timed activation of PKCθ, phosphorylation of EKLF at S68 by P-PKCθ(S676), and sumoylation of EKLF at K74. The latter EKLF modifications modulate its interactions with a cytoplasmic ankyrin-repeat-protein FOE and importinβ1, respectively. The role of FOE in the control of EKLF nuclear import is further supported by analysis of the subcellular distribution patterns of EKLF in FOE-knockout mice. This study reveals the regulatory mechanisms of the nuclear import of EKLF, which may also be utilized in the nuclear import of other factors. Copyright © 2014 Elsevier Inc. All rights reserved.

Orientation-adjusted anomalous insulator-metal transition in NdNiO3/LaMnO3 bilayers

NASA Astrophysics Data System (ADS)

Pan, S. Y.; Shi, L.; Zhao, J. Y.; Zhou, S. M.; Xu, X. M.

2018-04-01

NdNiO3/LaMnO3 (NNO/LMO) bilayers were epitaxially grown on SrTiO3 (STO) substrates with different orientations by the polymer-assisted deposition technique. A well crystallization quality of the bilayers is confirmed by X-ray diffraction. Two consecutive transitions, an anomalous insulator-metal transition at ˜100 K followed by the typical metal-insulator transition at ˜171 K, are observed in the (001)-oriented NNO/LMO/STO bilayer. The anomalous insulator-metal transition temperature increases to 142 K for the (111)-oriented NNO/LMO/STO bilayer. Meanwhile, the magnetic properties of the NNO/LMO bilayers show an obvious difference with [100] and [111] orientations. Considering the different strain directions and the related oxygen octahedral distortion/rotation, it is suggested that the magnetic changes and the low-temperature anomalous insulator-metal transition in the NNO/LMO bilayers are attributed to the strong interlayer exchange coupling and charge transfer adjusted by the substrate orientation, which can be an effective technique to tune the properties of transition-metal oxide films.

Ab initio study of dynamical E × e Jahn-Teller and spin-orbit coupling effects in the transition-metal trifluorides TiF3, CrF3, and NiF3

NASA Astrophysics Data System (ADS)

Mondal, Padmabati; Opalka, Daniel; Poluyanov, Leonid V.; Domcke, Wolfgang

2012-02-01

Multiconfiguration ab initio methods have been employed to study the effects of Jahn-Teller (JT) and spin-orbit (SO) coupling in the transition-metal trifluorides TiF3, CrF3, and NiF3, which possess spatially doubly degenerate excited states (ME) of even spin multiplicities (M = 2 or 4). The ground states of TiF3, CrF3, and NiF3 are nondegenerate and exhibit minima of D3h symmetry. Potential-energy surfaces of spatially degenerate excited states have been calculated using the state-averaged complete-active-space self-consistent-field method. SO coupling is described by the matrix elements of the Breit-Pauli operator. Linear and higher order JT coupling constants for the JT-active bending and stretching modes as well as SO-coupling constants have been determined. Vibronic spectra of JT-active excited electronic states have been calculated, using JT Hamiltonians for trigonal systems with inclusion of SO coupling. The effect of higher order (up to sixth order) JT couplings on the vibronic spectra has been investigated for selected electronic states and vibrational modes with particularly strong JT couplings. While the weak SO couplings in TiF3 and CrF3 are almost completely quenched by the strong JT couplings, the stronger SO coupling in NiF3 is only partially quenched by JT coupling.

Dynamical transitions associated with turbulence in a helicon plasma

NASA Astrophysics Data System (ADS)

Light, Adam D.; Tian, Li; Chakraborty Thakur, Saikat; Tynan, George R.

2017-10-01

Diagnostic capabilities are often cited as a limiting factor in our understanding of transport in fusion devices. Increasingly advanced multichannel diagnostics are being applied to classify transport regimes and to search for ``trigger'' features that signal an oncoming dynamical event, such as an ELM or an L-H transition. In this work, we explore a technique that yields information about global properties of plasma dynamics from a single time series of a relevant plasma quantity. Electrostatic probe data from the Controlled Shear Decorrelation eXperiment (CSDX) is analyzed using recurrence quantification analysis (RQA) in the context of previous work on the transition to weak drift-wave turbulence. The recurrence characteristics of a phase space trajectory provide a quantitative means to classify dynamics and identify transitions in a complex system. We present and quantify dynamical variations in the plasma variables as a function of the background magnetic field strength. A dynamical transition corresponding to the emergence of broadband fluctuations is identified using RQA measures.

Experimental and theoretical oscillator strengths of Mg I for accurate abundance analysis

NASA Astrophysics Data System (ADS)

Pehlivan Rhodin, A.; Hartman, H.; Nilsson, H.; Jönsson, P.

2017-02-01

Context. With the aid of stellar abundance analysis, it is possible to study the galactic formation and evolution. Magnesium is an important element to trace the α-element evolution in our Galaxy. For chemical abundance analysis, such as magnesium abundance, accurate and complete atomic data are essential. Inaccurate atomic data lead to uncertain abundances and prevent discrimination between different evolution models. Aims: We study the spectrum of neutral magnesium from laboratory measurements and theoretical calculations. Our aim is to improve the oscillator strengths (f-values) of Mg I lines and to create a complete set of accurate atomic data, particularly for the near-IR region. Methods: We derived oscillator strengths by combining the experimental branching fractions with radiative lifetimes reported in the literature and computed in this work. A hollow cathode discharge lamp was used to produce free atoms in the plasma and a Fourier transform spectrometer recorded the intensity-calibrated high-resolution spectra. In addition, we performed theoretical calculations using the multiconfiguration Hartree-Fock program ATSP2K. Results: This project provides a set of experimental and theoretical oscillator strengths. We derived 34 experimental oscillator strengths. Except from the Mg I optical triplet lines (3p 3P°0,1,2-4s 3S1), these oscillator strengths are measured for the first time. The theoretical oscillator strengths are in very good agreement with the experimental data and complement the missing transitions of the experimental data up to n = 7 from even and odd parity terms. We present an evaluated set of oscillator strengths, gf, with uncertainties as small as 5%. The new values of the Mg I optical triplet line (3p 3P°0,1,2-4s 3S1) oscillator strength values are 0.08 dex larger than the previous measurements.

Glass/Jamming Transition in Colloidal Aggregation

NASA Technical Reports Server (NTRS)

Segre, Philip N.; Prasad, Vikram; Weitz, David A.; Rose, M. Franklin (Technical Monitor)

2000-01-01

We have studied colloidal aggregation in a model colloid plus polymer system with short-range attractive interactions. By varying the colloid concentration and the strength of the attraction, we explored regions where the equilibrium phase is expected to consist of colloidal crystallites in coexistance with colloidal gas (i.e. monomers). This occurs for moderate values of the potential depth, U approximately equal to 2-5 kT. Crystallization was not always observed. Rather, over an extended sub-region two new metastable phases appear, one fluid-like and one solid-like. These were examined in detail with light scattering and microscopy techniques. Both phases consist of a near uniform distribution of small irregular shaped clusters of colloidal particles. The dynamical and structural characteristics of the ergodic-nonergodic transition between the two phases share much in common with the colloidal hard sphere glass transition.

E3 Success Story - Accelerating Adoption of E3 Recommendations

EPA Pesticide Factsheets

The state of Michigan, along with numerous local and state partners, formed E3 Michigan in 2010. This partnership will allow for up to 10 E3 assessments in southeast Michigan and 10 E3 assessments in western Michigan.

Studies on phase transition temperature of rare earth niobates Ln3NbO7 (Ln = Pr, Sm, Eu) with orthorhombic fluorite-related structure

NASA Astrophysics Data System (ADS)

Hinatsu, Yukio; Doi, Yoshihiro

2017-06-01

The phase transition of ternary rare earth niobates Ln3NbO7 (Ln = Pr, Sm, Eu) was investigated by the measurements of high-temperature and low-temperature X-ray diffraction, differential scanning calorimetry (DSC) and differential thermal analysis (DTA). These compounds crystallize in an orthorhombic superstructure derived from the structure of cubic fluorite (space group Pnma for Ln = Pr; C2221 for Ln = Sm, Eu). Sm3NbO7 undergoes the phase transition when the temperature is increased through ca. 1080 K and above the transition temperature, its structure is well described with space group Pnma. For Eu3NbO7, the phase transition was not observed up to 1273 K Pr3NbO7 indicates the phase transition when the temperature is increased through ca. 370 K. The change of the phase transition temperature against the Ln ionic radius for Ln3NbO7 is quite different from those for Ln3MO7 (M = Mo, Ru, Re, Os, or Ir), i.e., no systematic relationship between the phase transition temperature and the Ln ionic radius has been observed for Ln3NbO7 compounds.

Phase Transitions of KIO3 Ferroelectrics in Al2O3-Based Nanoporous Matrices

NASA Astrophysics Data System (ADS)

Milinskii, A. Yu.; Baryshnikov, S. V.

2018-03-01

Temperature dependences of the linear permittivity ɛ' and the third harmonic amplitude γ3ω of composites prepared by introducing ferroelectrics KIO3 into matrices of porous aluminum oxide Al2O3 with pore sizes of 240 nm were studied. It is found that the IV → III and III → II structural transition temperatures of potassium iodide in Al2O3 pores decrease by 5 K and 24 K, respectively, with respect to bulk KIO3. The measurements of the dielectric properties do not reveal V → IV and II → I phase transitions in the composite samples.

Phase transitions in 3D gravity and fractal dimension

NASA Astrophysics Data System (ADS)

Dong, Xi; Maguire, Shaun; Maloney, Alexander; Maxfield, Henry

2018-05-01

We show that for three dimensional gravity with higher genus boundary conditions, if the theory possesses a sufficiently light scalar, there is a second order phase transition where the scalar field condenses. This three dimensional version of the holographic superconducting phase transition occurs even though the pure gravity solutions are locally AdS3. This is in addition to the first order Hawking-Page-like phase transitions between different locally AdS3 handlebodies. This implies that the Rényi entropies of holographic CFTs will undergo phase transitions as the Rényi parameter is varied, as long as the theory possesses a scalar operator which is lighter than a certain critical dimension. We show that this critical dimension has an elegant mathematical interpretation as the Hausdorff dimension of the limit set of a quotient group of AdS3, and use this to compute it, analytically near the boundary of moduli space and numerically in the interior of moduli space. We compare this to a CFT computation generalizing recent work of Belin, Keller and Zadeh, bounding the critical dimension using higher genus conformal blocks, and find a surprisingly good match.

Field-induced polarization rotation and phase transitions in 0.70 Pb ( M g 1 / 3 N b 2 / 3 ) O 3 – 0.30 PbTi O 3 piezoceramics observed by in situ high-energy x-ray scattering

DOE PAGES

Hou, Dong; Usher, Tedi -Marie; Fulanovic, Lovro; ...

2018-06-12

Changes to the crystal structure of 0.70Pb(Mg 1/3Nb 2/3)O 3–0.30PbTiO 3 (PMN-0.30PT) piezoceramic under application of electric fields at the long-range and local scale are revealed by in situ high-energy x-ray diffraction (XRD) and pair-distribution function (PDF) analyses, respectively. The crystal structure of unpoled samples is identified as monoclinic Cm at both the long-range and local scale. In situ XRD results suggest that field-induced polarization rotation and phase transitions occur at specific field strengths. A polarization rotation pathway is proposed based on the Bragg-peak behaviors and the Le Bail fitting results of the in situ XRD patterns. The PDF resultsmore » show systematic changes to the structures at the local scale, which is in agreement with the changes inferred from the in situ XRD study. More importantly, our results prove that polarization rotation can be detected and determined in a polycrystalline relaxor ferroelectric. Furthermore, this study supports the idea that multiple contributions, specifically ferroelectric-ferroelectric phase transition and polarization rotation, are responsible for the high piezoelectric properties at the morphotropic phase boundary of PMN-xPT piezoceramics.« less

Field-induced polarization rotation and phase transitions in 0.70 Pb ( M g 1 / 3 N b 2 / 3 ) O 3 – 0.30 PbTi O 3 piezoceramics observed by in situ high-energy x-ray scattering

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

Hou, Dong; Usher, Tedi -Marie; Fulanovic, Lovro

Changes to the crystal structure of 0.70Pb(Mg 1/3Nb 2/3)O 3–0.30PbTiO 3 (PMN-0.30PT) piezoceramic under application of electric fields at the long-range and local scale are revealed by in situ high-energy x-ray diffraction (XRD) and pair-distribution function (PDF) analyses, respectively. The crystal structure of unpoled samples is identified as monoclinic Cm at both the long-range and local scale. In situ XRD results suggest that field-induced polarization rotation and phase transitions occur at specific field strengths. A polarization rotation pathway is proposed based on the Bragg-peak behaviors and the Le Bail fitting results of the in situ XRD patterns. The PDF resultsmore » show systematic changes to the structures at the local scale, which is in agreement with the changes inferred from the in situ XRD study. More importantly, our results prove that polarization rotation can be detected and determined in a polycrystalline relaxor ferroelectric. Furthermore, this study supports the idea that multiple contributions, specifically ferroelectric-ferroelectric phase transition and polarization rotation, are responsible for the high piezoelectric properties at the morphotropic phase boundary of PMN-xPT piezoceramics.« less

Fracture strength of four different types of anterior 3-unit bridges after thermo-mechanical fatigue in the dual-axis chewing simulator.

PubMed

Kheradmandan, S; Koutayas, S O; Bernhard, M; Strub, J R

2001-04-01

The purpose of this study was to evaluate the fracture strength of four different types of anterior 3-unit bridges after thermo-mechanical fatigue in a dual-axis chewing simulator. Sixty-four human maxillary incisors were prepared and 32 bridges fabricated. The four groups of eight bridges each were - (GC): AGC(R) galvano-ceramic bridges (CA): Celay(R) In-Ceram(R) Alumina bridges (E2): heat-pressed lithium disilicate glass-ceramic bridges and (CM) ceramo-metal (control). Fracture loads were recorded after a dual-axis chewing simulator and in a universal testing machine. The survival rate after 5 years for the CM and the GC groups was 100%, for the E2 group 75% and for the CA group 37.5% (Kaplan-Mayer analysis). The mean fracture strengths (N) were 681.52 +/- 151.90 (CM); 397.71 +/- 59.02 (GC); 292.92 +/- 46.45 (E2) and 239.95 +/- 33.39 (CA), respectively. The log-rank test showed a significant difference between the CA and the GC or the CA and the CM groups. No significant differences between the E2 and the CA or the E2 and the GC groups were found. The study indicates that heat-pressed lithium disilicate glass-ceramic and AGC(R) galvano-ceramic bridges are alternatives to ceramo-metal 3-unit anterior bridges.

Line Shapes and Intensities of Carbon Monoxide Transitions in the (3→0) and (4→1) Bands

NASA Astrophysics Data System (ADS)

Reed, Zachary; Polyansky, Oleg; Hodges, Joseph T.

2017-06-01

We have measured several carbon monoxide transitions in the (3→0) and (4→1) band using frequency stabilized cavity ringdown spectroscopy (FS-CRDS). The measured transitions are compared to the line strength values in HITRAN 2012 [1], those determined by Wojtewitz et al [2], and to theoretical calculations. The cavity length is actively locked to an iodine stabilized HeNe laser, providing long term frequency stability of 10 kHz and is linked to a self-referenced, octave-spanning frequency comb. The temperature of the optical cavity is actively regulated at the mK level, and the pressure measurements are SI-traceable. The sample is a NIST calibrated reference mixture of 11.98575(95)% CO in N_{2}. The absorption spectra are modeled using the Hartmann-Tran profile (HTP). The SNR in these spectra may exceed 10,000:1, which necessitates including the effects of speed dependence, collisional narrowing, and correlation between velocity-changing and dephasing collisions. The relative uncertainties of the line strengths calculated in this study are better than 0.1%. There are systematic differences on the 1% level for ^{12}CO against both HITRAN [1] and the previous work by Wojtewitz et al [2]. The measurement uncertainties are nearly an order of magnitude lower than previous results. Additionally, the relative uncertainties in the integrated areas of selected ^{12}CO and ^{13}CO transitions are less than 0.006% and 0.02%, respectively, providing an excellent test case for determination of isotope ratios by direct use of theoretical line intensity calculations. [1] Wojtewicz, S., et al., J Quant Spect and Rad Trans,2013. 130: p.191-200. [2]Rothman, L.S., et al., Journal of Quant Spect and Rad Trans, 2013. 130: p. 4-50.

A comparison of hand grasp breakaway strengths and bare-handed grip strengths of the astronauts, SML 3 test subjects, and the subjects from the general population

NASA Technical Reports Server (NTRS)

Rajulu, Sudhakar L.; Klute, Glenn K.

1993-01-01

Astronauts have the task of retrieving and deploying satellites and handling massive objects in a around the payload bay. Concerns were raised that manual handling of such massive objects might induce loads to the shuttle suits exceeding the design-certified loads. The Crew and Thermal Division of NASA JSC simulated the satellite handling tasks (Satellite Manload Tests 1 and 3) and determined the maximum possible load that a suited member could impart onto the suit. In addition, the tests revealed that the load to the suit by an astronaut could be calculated from the astronaut's maximum hand grasp breakaway strength. Thus, this study was conducted to document that hand grasp breakaway strengths of the astronauts who were scheduled to perform EVA during the upcoming missions. In addition, this study verified whether the SML 3 test results were sufficient for documenting the maximum possible load. An attempt was made to predict grasp strength from grip strength and hand anthropometry. Based on the results from this study, the SML 3 test results were deemed sufficient to document the maximum possible load on the suit. Finally, prediction of grasp strength from grip strength was not as accurate as expected. Hence, it was recommended that grasp strength be collected from the astronauts in order to obtain accurate load estimation.

Strength and microstructure of sintered Si3N4 with rare-earth-oxide additions

NASA Technical Reports Server (NTRS)

Sanders, W. A.; Mieskowski, D. M.

1985-01-01

Room temperature, 700-, 1000-, 1200-, and 1370-C examinations of the effect of 1.7-2.6 mol pct rare earth oxide additions to sintered Si3N4 are conducted. While the room temperature-1000 C bend strengths were higher for this material with Y2O3 additions than with CeO2, La2O3, or Sm2O3, the reverse was true at 1200-1370 C. This phenomenon is explained on the basis of microstructural differences, since quantitative microscopy of SEM replicas showed the Si3N4-Y2O3 composition to contain both a higher percentage of elongated grains and a coarser microstructure than the other three alternatives. The elongated grains appear to increase this composition's low temperature strength irrespective of microstructural coarseness; this coarseness, however, decreases strength relative to the other compositions at higher temperatures.

Multiple magnetic transitions in EuNiSi3

NASA Astrophysics Data System (ADS)

Patil, Sujata M.; Paulose, P. L.

2018-04-01

EuNiSi3 undergoes multiple magnetic transitions below 50K. We have studied this system using low field ac susceptibility and 151Eu Mössbauer spectroscopy to understand the nature of multiple magnetic transitions. The estimated hyperfine field (hf) at Eu site at 5K is 45 Tesla which is unusually large compared to the normal observed hf of 33T in most of the Eu intermetallics.

Dimensional crossover of effective orbital dynamics in polar distorted He 3 -A : Transitions to antispacetime

NASA Astrophysics Data System (ADS)

Nissinen, J.; Volovik, G. E.

2018-01-01

Topologically protected superfluid phases of He 3 allow one to simulate many important aspects of relativistic quantum field theories and quantum gravity in condensed matter. Here we discuss a topological Lifshitz transition of the effective quantum vacuum in which the determinant of the tetrad field changes sign through a crossing to a vacuum state with a degenerate fermionic metric. Such a transition is realized in polar distorted superfluid He 3 -A in terms of the effective tetrad fields emerging in the vicinity of the superfluid gap nodes: the tetrads of the Weyl points in the chiral A-phase of He 3 and the degenerate tetrad in the vicinity of a Dirac nodal line in the polar phase of He 3 . The continuous phase transition from the A -phase to the polar phase, i.e., the transition from the Weyl nodes to the Dirac nodal line and back, allows one to follow the behavior of the fermionic and bosonic effective actions when the sign of the tetrad determinant changes, and the effective chiral spacetime transforms to antichiral "anti-spacetime." This condensed matter realization demonstrates that while the original fermionic action is analytic across the transition, the effective action for the orbital degrees of freedom (pseudo-EM) fields and gravity have nonanalytic behavior. In particular, the action for the pseudo-EM field in the vacuum with Weyl fermions (A-phase) contains the modulus of the tetrad determinant. In the vacuum with the degenerate metric (polar phase) the nodal line is effectively a family of 2 +1 d Dirac fermion patches, which leads to a non-analytic (B2-E2)3/4 QED action in the vicinity of the Dirac line.

Reduced probabilities for E2 transitions between excited collective states of triaxial even–even nuclei

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

Nadyrbekov, M. S., E-mail: nodirbekov@inp.uz; Bozarov, O. A.

Reduced probabilities for intra- and interband E2 transitions in excited collective states of even–even lanthanide and actinide nuclei are analyzed on the basis of a model that admits an arbitrary triaxiality. They are studied in detail in the energy spectra of {sup 154}Sm, {sup 156}Gd, {sup 158}Dy, {sup 162,164}Er, {sup 230,232}Th, and {sup 232,234,236,238}U even–even nuclei. Theoretical and experimental values of the reduced probabilities for the respective E2 transitions are compared. This comparison shows good agreement for all states, including high-spin ones. The ratios of the reduced probabilities for the E2 transitions in question are compared with results following frommore » the Alaga rules. These comparisons make it possible to assess the sensitivity of the probabilities being considered to the presence of quadrupole deformations.« less

Strength and durability of concrete: Effects of cement paste-aggregate interfaces. Part 2: Significance of transition zones on physical and mechanical properties of portland cement mortar; Final report

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

Lee, T.F.F.; Cohen, M.D.; Chen, W.F.

1998-08-01

The research was based on a two-part basic research investigation studying the effects of cement paste-aggregate interfaces (or interfacial transition zones-ITZ) on strength and durability of concrete. Part 1 dealt with the theoretical study and Part 2 dealt with the experimental.

Strength and durability of concrete: Effects of cement paste-aggregate interfaces. Part 1: Theoretical study on influence of interfacial transition zone on properties of concrete materials; Final report

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

Zhang, Y.; Chen, W.F.

1998-08-01

This research was based on a two-part basic research investigation studying the effects of cement paste-aggregate interfaces (or interfacial transition zones-ITZ) on strength and durability of concrete. Part 1 dealt with the theoretical study and Part 2 dealt with the experimental.

High pressure ferroelastic phase transition in SrTiO3

NASA Astrophysics Data System (ADS)

Salje, E. K. H.; Guennou, M.; Bouvier, P.; Carpenter, M. A.; Kreisel, J.

2011-07-01

High pressure measurements of the ferroelastic phase transition of SrTiO3 (Guennou et al 2010 Phys. Rev. B 81 054115) showed a linear pressure dependence of the transition temperature between the cubic and tetragonal phase. Furthermore, the pressure induced transition becomes second order while the temperature dependent transition is near a tricritical point. The phase transition mechanism is characterized by the elongation and tilt of the TiO6 octahedra in the tetragonal phase, which leads to strongly nonlinear couplings between the structural order parameter, the volume strain and the applied pressure. The phase diagram is derived from the Clausius-Clapeyron relationship and is directly related to a pressure dependent Landau potential. The nonlinearities of the pressure dependent strains lead to an increase of the fourth order Landau coefficient with increasing pressure and, hence, to a tricritical-second order crossover. This behaviour is reminiscent of the doping related crossover in isostructural KMnF3.

Tensile Strength and Microstructure of Al2O3-ZrO2 Hypo-Eutectic Fibers Studied

NASA Technical Reports Server (NTRS)

Farmer, Serene C.; Sayir, Ali

2001-01-01

Oxide eutectics offer high-temperature strength retention and creep resistance in oxidizing environments. Al2O3-ZrO2 eutectic strengths have been studied since the 1970's. Directionally solidified oxide eutectics exhibit improved resistance to slow crack growth and excellent strength retention at high temperatures up to 1400 C. Materials studied typically contain Y2O3 to metastably retain the high-temperature cubic and tetragonal polymorphs at room temperature. Al2O3-ZrO2 is of fundamental interest for creep studies because it combines a creep-resistant material, Al2O3, with a very low creep resistance material, ZrO2. Results on mechanical properties and microstructures of these materials will be used to define compositions for creep testing in future work. Substantial variations from the eutectic alumina to zirconia ratio can be tolerated without a loss in room-temperature strength. The effect of increasing Y2O3 addition on the room-temperature tensile strength of an Al2O3-ZrO2 material containing excess Al2O3 was examined at the NASA Glenn Research Center, where the materials were grown using Glenn's world-class laser growth facilities.

Overexpression of microRNA-194 suppresses the epithelial-mesenchymal transition in targeting stem cell transcription factor Sox3 in endometrial carcinoma stem cells.

PubMed

Gong, Baolan; Yue, Yan; Wang, Renxiao; Zhang, Yi; Jin, Quanfang; Zhou, Xi

2017-06-01

The epithelial-mesenchymal transition is the key process driving cancer metastasis. MicroRNA-194 inhibits epithelial-mesenchymal transition in several cancers and its downregulation indicates a poor prognosis in human endometrial carcinoma. Self-renewal factor Sox3 induces epithelial-mesenchymal transition at gastrulation and is also involved epithelial-mesenchymal transition in several cancers. We intended to determine the roles of Sox3 in inducing epithelial-mesenchymal transition in endometrial cancer stem cells and the possible role of microRNA-194 in controlling Sox3 expression. Firstly, we found that Sox3 and microRNA-194 expressions were associated with the status of endometrial cancer stem cells in a panel of endometrial carcinoma tissue, the CD133+ cell was higher in tumorsphere than in differentiated cells, and overexpression of microRNA-194 would decrease CD133+ cell expression. Silencing of Sox3 in endometrial cancer stem cell upregulated the epithelial marker E-cadherin, downregulated the mesenchymal marker vimentin, and significantly reduced cell invasion in vitro; overexpression of Sox3 reversed these phenotypes. Furthermore, we discovered that the expression of Sox3 was suppressed by microRNA-194 through direct binding to the Sox3 3'-untranslated region. Ectopic expression of microRNA-194 in endometrial cancer stem cells induced a mesenchymal-epithelial transition by restoring E-cadherin expression, decreasing vimentin expression, and inhibiting cell invasion in vitro. Moreover, overexpression of microRNA-194 inhibited endometrial cancer stem cell invasion or metastasis in vivo by injection of adenovirus microRNA-194. These findings demonstrate the novel mechanism by which Sox3 contributes to endometrial cancer stem cell invasion and suggest that repression of Sox3 by microRNA-194 may have therapeutic potential to suppress endometrial carcinoma metastasis. The cancer stem cell marker, CD133, might be the surface marker of endometrial cancer stem

The Self-energy Of Growing Aggregates: "Strength Regime"

NASA Astrophysics Data System (ADS)

Guimaraes, Ana H. F.; Spahn, F.; Seiss, M.; Brilliantov, N. V.

2009-09-01

The vivid appearance of the outer regions of Saturn's rings points to a balance of ongoing fragmentation and coagulation processes. This idea finds support especially in the F-ring, where collisional processes occur on an almost daily basis stirred by perturbations of the satellites Prometheus and Pandora, and in addition due the presence of putative moonlets. In order to quantify this balance in a kinetic theory we propose to calculate the resistivity of small agglomerates ("dynamic ephemeral bodies") against rupture due collisional processes and tidal pull. Earlies studies have shown that the resistivity of an aggregate is divided into two phases: "strength regime" and "gravitational regime". Early in their formation, small agglomerates are supported basically by their "glue" between the particles (adhesion) - "strength regime". For larger agglomerates the "gravitational regime" takes over provided their sizes to be bigger than a threshold in which the self-gravitational energy exceeds the adhesive binding energy, in this case the cluster's constituents are held together gravitationally. We calculated the self-energy caused by adhesion and gravity of ring's aggregates which has been considered as the threshold of impact energy or of tidal work to disrupt the agglomerate. Using a Ballistic Particle Cluster Aggregate Model (BPCA) we varied the densities of the aggregates and the size distribution of their constituents (1-10cm), calculated their self-energy and identified the transition between the "strength" to "gravitational regime". The transition between the regimes occurs at house-size aggregates (diameter of approximately 20m), a fact, that fits to the cut-off on the dense rings' main population (cm - 5m in size). Acknowledgments: A.H.F.G. thanks Dr. E. Vieira-Neto for the discussions, and also the DAAD and Uni-Potsdam for the financial support of this project.

The Transition Period in Soccer: A Window of Opportunity.

PubMed

Silva, Joao Renato; Brito, Joao; Akenhead, Richard; Nassis, George P

2016-03-01

The aim of this paper is to describe the physiological changes that occur during the transition period in soccer players. A secondary aim is to address the issue of utilizing the transition period to lay the foundation for the succeeding season. We reviewed published peer-reviewed studies if they met the following three selection criteria: (1) the studied population comprised adult soccer players (aged >18 years), (2) time points of physiological and performance assessments were provided, and (3) appropriate statistics for the calculation of effect sizes were reported. Following two selection phases, 12 scientific publications were considered, involving a total sample of 252 players. The transition period elicits small to moderate negative changes in body composition, a moderate decline in sprint performance with and without changes of direction, and small to moderate decrements in muscle power. Detraining effects are also evident for endurance-related physiological and performance outcomes: large decrements in maximal oxygen consumption V̇O2max) and time to exhaustion, and moderate to very large impairments have been observed in intermittent-running performance. Off-season programs should be characterized by clear training objectives, a low frequency of training sessions, and simple training tools in order to facilitate compliance. The program suggested here may constitute the 'minimum effective dose' to maintain or at least attenuate the decay of endurance- and neuromuscular-related performance parameters, as well as restore an adequate strength profile (reduce muscle strength imbalances). This periodization strategy may improve the ability of players to cope with the elevated training demands of pre-season training and therefore reduce the risk of injury. Moreover, this strategy will favor a more efficient development of other relevant facets of performance during the pre-competition phase (e.g., tactical organization). We contend that the transition period

Different Patterns in Muscular Strength and Hypertrophy Adaptations in Untrained Individuals Undergoing Nonperiodized and Periodized Strength Regimens.

PubMed

De Souza, Eduardo O; Tricoli, Valmor; Rauch, Jacob; Alvarez, Michael R; Laurentino, Gilberto; Aihara, André Y; Cardoso, Fabiano N; Roschel, Hamilton; Ugrinowitsch, Carlos

2018-05-01

De Souza, EO, Tricoli, V, Rauch, J, Alvarez, MR, Laurentino, G, Aihara, AY, Cardoso, FN, Roschel, H, and Ugrinowitsch, C. Different patterns in muscular strength and hypertrophy adaptations in untrained individuals undergoing non-periodized and periodized strength regimens. J Strength Cond Res 32(5): 1238-1244, 2018-This study investigated the effects of nonperiodized (NP), traditional periodization (TP), and daily undulating periodization (UP) regimens on muscle strength and hypertrophy in untrained individuals. Thirty-three recreationally active males were randomly divided into 4 groups: NP: n = 8; TP: n = 9; UP: n = 8, and control group (C): n = 8. Experimental groups underwent a 12-week strength training program consisting of 2 sessions per week. Muscle strength and quadriceps cross-sectional area (QCSA) were assessed at baseline, 6 weeks (i.e., mid-point) and after 12 weeks. All training groups increased squat 1RM from pre to 6 weeks mid (NP: 17.02%, TP: 7.7%, and UP: 12.9%, p ≤ 0.002) and pre to post 12 weeks (NP: 19.5%, TP: 17.9%, and UP: 20.4%, p ≤ 0.0001). Traditional periodization was the only group that increased squat 1RM from 6 weeks mid to 12-week period (9.4%, p ≤ 0.008). All training groups increased QCSA from pre to 6 weeks mid (NP: 5.1%, TP: 4.6%, and UP: 5.3%, p ≤ 0.0006) and from pre to post 12 weeks (NP: 8.1%, TP: 11.3%, and UP: 8.7%, p ≤ 0.0001). From 6 weeks mid to 12-week period, TP and UP were the only groups that increased QCSA (6.4 and 3.7%, p ≤ 0.02). There were no significant changes for all dependent variables in C group across the time (p ≥ 0.05). In conclusion, our results demonstrated similar training-induced adaptations after 12 weeks of NP and periodized regimens. However, our findings suggest that in the latter half of the study (i.e., after the initial 6 weeks), the periodized regimens elicited greater rates of muscular adaptations compared with NP regimens. Strength coaches and practitioners should be aware that

Formal Valence, 3 d Occupation, and Charge Ordering Transitions

NASA Astrophysics Data System (ADS)

Pickett, Warren

2014-03-01

The metal-insulator transition (MIT), discovered by Verwey in the late 1930s, has been thought to be one of the best understood of MITs, the other ones being named after Wigner, Peierls, Mott, and Anderson. Continuing work on these transitions finds in some cases less and less charge to order, raising the fundamental question of just where the entropy is coming from, and just what is ordering. To provide insight into the mechanism of charge-ordering transitions, which conventionally are pictured as a disproportionation, I will (1) review and reconsider the charge state (or oxidation number) picture itself, (2) introduce new theoretical results for the rare earth nickelates (viz. YNiO3), the putative charge ordering compound AgNiO2, and the dual charge state insulator AgO, and (3) analyze cationic occupations of actual (not formal) charge, and work to reconcile the conundrums that arise. Several of the clearest cases of charge ordering transitions involve no disproportion; moreover, the experimental data used to support charge ordering can be accounted for within density functional based calculations that contain no charge transfer The challenge of modeling charge ordering transitions with model Hamiltonians will be discussed. Acknowledgment: Y. Quan, V. Pardo. Supported by NSF award DMR-1207622-0.

REVISITING {rho}{sup 1} CANCRI e: A NEW MASS DETERMINATION OF THE TRANSITING SUPER-EARTH

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

Endl, Michael; Cochran, William D.; MacQueen, Phillip J.

2012-11-01

We present a mass determination for the transiting super-Earth {rho}{sup 1} Cancri e based on nearly 700 precise radial velocity (RV) measurements. This extensive RV data set consists of data collected by the McDonald Observatory planet search and published data from Lick and Keck observatories. We obtained 212 RV measurements with the Tull Coude Spectrograph at the Harlan J. Smith 2.7 m Telescope and combined them with a new Doppler reduction of the 131 spectra that we have taken in 2003-2004 with the High-Resolution Spectrograph (HRS) at the Hobby-Eberly Telescope for the original discovery of {rho}{sup 1} Cancri e. Usingmore » this large data set we obtain a five-planet Keplerian orbital solution for the system and measure an RV semi-amplitude of K = 6.29 {+-} 0.21 m s{sup -1} for {rho}{sup 1} Cnc e and determine a mass of 8.37 {+-} 0.38 M {sub Circled-Plus }. The uncertainty in mass is thus less than 5%. This planet was previously found to transit its parent star, which allowed them to estimate its radius. Combined with the latest radius estimate from Gillon et al., we obtain a mean density of {rho} = 4.50 {+-} 0.20 g cm{sup -3}. The location of {rho}{sup 1} Cnc e in the mass-radius diagram suggests that the planet contains a significant amount of volatiles, possibly a water-rich envelope surrounding a rocky core.« less

Electron impact excitation of the 1{sup 1}{ital S}{r_arrow}3{sup 1}{ital P} transition in helium

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

Khakoo, M.A.; Roundy, D.; Rugamas, F.

1995-07-03

In the first direct application of the electron-photon coincidence technique for differential cross-section measurements, experimentally determined ratios of the differential cross sections for the electron impact excitation of the 1{sup 1}{ital S}{r_arrow}2{sup 1}{ital P} to the 1{sup 1}{ital S}{r_arrow}3{sup 1}{ital P} transitions are presented at 30 and 40 eV incident electron energies. Differential cross sections for the 1{sup 1}{ital S}{r_arrow}3{sup 1}{ital P} transitions are derived by normalizing these ratios to available experimental differential cross sections for the 1{sup 1}{ital S}{r_arrow}2{sup 1}{ital P} transition.

Elasticity and Strength of Biomacromolecular Crystals: Lysozyme

NASA Technical Reports Server (NTRS)

Holmes, A. M.; Witherow, W. K.; Chen, L. Q.; Chernov, A. A.

2003-01-01

The static Young modulus, E = 0.1 to 0.5 GPa, the crystal critical strength (sigma(sub c)) and its ratio to E,sigma(sub c)/E is approximately 10(exp 3), were measured for the first time for non cross-linked lysozyme crystals in solution. By using a triple point bending apparatus, we also demonstrated that the crystals were purely elastic. Softness of protein crystals built of hard macromolecules (26 GPa for lysozyme) is explained by the large size of the macromolecules as compared to the range of intermolecular forces and by the weakness of intermolecular bonds as compared to the peptide bond strength. The relatively large reported dynamic elastic moduli (approximately 8 GPa) from resonance light scattering should come from averaging over the moduli of intracrystalline water and intra- and intermolecular bonding.

On the nature of the Mott transition in multiorbital systems

NASA Astrophysics Data System (ADS)

Facio, Jorge I.; Vildosola, V.; García, D. J.; Cornaglia, Pablo S.

2017-02-01

We analyze the nature of a Mott metal-insulator transition in multiorbital systems using dynamical mean-field theory. The auxiliary multiorbital quantum impurity problem is solved using continuous-time quantum Monte Carlo and the rotationally invariant slave-boson (RISB) mean-field approximation. We focus our analysis on the Kanamori Hamiltonian and find that there are two markedly different regimes determined by the nature of the lowest-energy excitations of the atomic Hamiltonian. The RISB results at T →0 suggest the following rule of thumb for the order of the transition at zero temperature: a second-order transition is to be expected if the lowest-lying excitations of the atomic Hamiltonian are charge excitations, while the transition tends to be first order if the lowest-lying excitations are in the same charge sector as the atomic ground state. At finite temperatures, the transition is first order and its strength, as measured, e.g., by the jump in the quasiparticle weight at the transition, is stronger in the parameter regime where the RISB method predicts a first-order transition at zero temperature. Interestingly, these results seem to apply to a wide variety of models and parameter regimes.

Electron Excitation Cross Sections for the 2s(sup 2)2p(sup 3) (sup 4)S -> 2s(sup 2)2p(sup 3) (sup 2d) ->2s2p(sup 4) (sup 4p) (Resonance) Transitions in Oil

NASA Technical Reports Server (NTRS)

Zuo, M.; Smith, S.; Chutjian, A.; Williams, I.; Tayal, S.; McLaughlin, B.

1994-01-01

Experimental and theoretical excitation cross sections are reported for the first forbidden transition xxx and the first allowed (resonance) transition xxx in OII. Use is made of electron-energy loss and merged beams methods. The electron energy range covered is 3.33 eV (threshold) to 15 eV for the S->D transition, and 14.9 eV (threshold) to 40 eV for the S->P transition. Care was taken to assess and minimize the metastable fraction of the OII beam. An electron mirror was designed and tested to reflect inelastically back-scattered electrons into the forward direction to account for the full range of polar scattering angles. Comparisons are made between present experiments and 11-state R-Matrix calculations. Calculations are also presented for the xxx transition.

(Finite) statistical size effects on compressive strength.

PubMed

Weiss, Jérôme; Girard, Lucas; Gimbert, Florent; Amitrano, David; Vandembroucq, Damien

2014-04-29

The larger structures are, the lower their mechanical strength. Already discussed by Leonardo da Vinci and Edmé Mariotte several centuries ago, size effects on strength remain of crucial importance in modern engineering for the elaboration of safety regulations in structural design or the extrapolation of laboratory results to geophysical field scales. Under tensile loading, statistical size effects are traditionally modeled with a weakest-link approach. One of its prominent results is a prediction of vanishing strength at large scales that can be quantified in the framework of extreme value statistics. Despite a frequent use outside its range of validity, this approach remains the dominant tool in the field of statistical size effects. Here we focus on compressive failure, which concerns a wide range of geophysical and geotechnical situations. We show on historical and recent experimental data that weakest-link predictions are not obeyed. In particular, the mechanical strength saturates at a nonzero value toward large scales. Accounting explicitly for the elastic interactions between defects during the damage process, we build a formal analogy of compressive failure with the depinning transition of an elastic manifold. This critical transition interpretation naturally entails finite-size scaling laws for the mean strength and its associated variability. Theoretical predictions are in remarkable agreement with measurements reported for various materials such as rocks, ice, coal, or concrete. This formalism, which can also be extended to the flowing instability of granular media under multiaxial compression, has important practical consequences for future design rules.

Experimental and theoretical methods to study structural phase transition mechanisms in K{sub 3}WO{sub 3}F{sub 3} oxyfluoride

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

Krylov, A.S., E-mail: shusy@iph.krasn.ru; Sofronova, S.N.; Kolesnikova, E.M.

2014-10-15

The results of structural phase transitions mechanisms study in K{sub 3}WO{sub 3}F{sub 3}oxyfluoride are represented by different experimental and theoretical methods. The structural phase transition anomalies at T{sub 1}=452 K and T{sub 2}=414 K of Raman and IR spectra have been analyzed. Using vibrational spectroscopy methods, the NMR-experiment has been done to clarify the nature of found phase transitions: displacive types or order-disorder types. The model of “disordered” crystal was proposed, and the results of lattice dynamics calculation in frameworks of the generalized Gordon–Kim method of ordered (R3) and “disordered” crystals were compared. The high pressure phases were studied bymore » the Raman technique too. - Graphical abstract: (1) Two possible configuration of octahedra. (2). All phases Raman lines of octahedra. (3) All phases IR lines of octahedra. (4) NMR spectra of all phases. - Highlights: • The results of study oxyfluoride K{sub 3}WO{sub 3}F{sub 3} are represented by Raman, IR, NMR technique. • The high pressure phases were studied by the Raman technique. • The anionic octahedra [WO{sub 3}F{sub 3}]{sup 3−} are not ordered below the both phase transitions. • The ferroelectric phase is realized due to the shift of atoms without F/O ordering. • Both of found phase transitions are close to the second order.« less

Temperature Variations and N+/O+ in the Orion Nebula II. The Collision Strengths

NASA Astrophysics Data System (ADS)

Rubin, R. H.; Dufour, R. J.; Martin, P. G.; Ferland, G. J.; Baldwin, J. A.; Ortiz, C. O.; Walter, D. K.

2001-03-01

We continue an investigation of electron temperature (T[e]), mean-square T[e] variation (t2), and the N+/O+ abundance ratio. Our previous analysis of HST spectra of the Orion Nebula used collision strengths for N+ by Stafford et al. (1994). Here we examine the consequences of changing just these collision strengths by using those of Lennon & Burke (1994). Rather than utilize the standard analytical, low electron density (N[e]) regime treatment for the analysis, we develop a numerical technique that is valid at any density. With Stafford et al. collision strengths, we find the average N[e] for the (N+, O+)-zone is 7500 cm-3, the average T[e] is 9160 K, t2 is 0.045, and N+/O+ is 0.14. Using Lennon & Burke values, the ``best" solution is found when these respective quantities are: 9000 cm-3, 9920 K, 0.00073, and 0.15. The value for t2 is dramatically lower than that found using Stafford et al. data.

Radiative transitions involving the (2p2)(3 Pe) metastable autodetaching of H(-)

NASA Technical Reports Server (NTRS)

Jacobs, V. L.; Bhatia, A. K.; Temkin, A.

1974-01-01

The absorption coefficient for the free-bound transition H (ls) + e(-)+ h omega yields H(-)(2 sq p,(3)P(e)) is calculated (together with the differential emission rate for the inverse process) using ls - 2s - 2p close coupling continuum wave functions and a Hylleraas bound state wave function. A maximum in the absorption and emission spectra is found to occur at a photon wavelength of 1219.5 A, which is 2 A closer to the Lyman alpha line than predicted by the calculations of Drake, and is in closer agreement with the stellar absorption feature identified by Heap and Stecher. The free-bound absorption process appears to be a significant source of continuous ultraviolet opacity.

BAG3 regulates epithelial-mesenchymal transition and angiogenesis in human hepatocellular carcinoma.

PubMed

Xiao, Heng; Cheng, Shaobing; Tong, Rongliang; Lv, Zheng; Ding, Chaofeng; Du, Chengli; Xie, Haiyang; Zhou, Lin; Wu, Jian; Zheng, Shusen

2014-03-01

Bcl2-associated athanogene 3 (BAG3) protein is a co-chaperone of heat-shock protein (Hsp) 70 and may regulate major physiological and pathophysiological processes. However, few reports have examined the role of BAG3 in human hepatocellular carcinoma (HCC). In this study, we show that BAG3 regulates epithelial-mesenchymal transition (EMT) and angiogenesis in HCC. BAG3 was overexpressed in HCC tissues and cell lines. BAG3 knockdown resulted in reduction in migration and invasion of HCC cells, which was linked to reversion of EMT by increasing E-cadherin expression and decreasing N-cadherin, vimentin and slug expression, as well as suppressing matrix metalloproteinase 2 (MMP-2) expression. In a xenograft tumorigenicity model, BAG3 knockdown effectively inhibited tumor growth and metastasis through reduction in CD34 and VEGF expression and reversal of the EMT pathway. In conclusion, BAG3 is associated with the invasiveness and angiogenesis in HCC, and the BAG3 gene may be a novel therapeutic approach against HCC.

Spatiotemporal dynamics of the spin transition in [Fe (HB(tz)3) 2] single crystals

NASA Astrophysics Data System (ADS)

Ridier, Karl; Rat, Sylvain; Shepherd, Helena J.; Salmon, Lionel; Nicolazzi, William; Molnár, Gábor; Bousseksou, Azzedine

2017-10-01

The spatiotemporal dynamics of the spin transition have been thoroughly investigated in single crystals of the mononuclear spin-crossover (SCO) complex [Fe (HB (tz )3)2] (tz = 1 ,2 ,4-triazol-1-yl) by optical microscopy. This compound exhibits an abrupt spin transition centered at 334 K with a narrow thermal hysteresis loop of ˜1 K (first-order transition). Most single crystals of this compound reveal exceptional resilience upon repeated switching (several hundred cycles), which allowed repeatable and quantitative measurements of the spatiotemporal dynamics of the nucleation and growth processes to be carried out. These experiments revealed remarkable properties of the thermally induced spin transition: high stability of the thermal hysteresis loop, unprecedented large velocities of the macroscopic low-spin/high-spin phase boundaries up to 500 µm/s, and no visible dependency on the temperature scan rate. We have also studied the dynamics of the low-spin → high-spin transition induced by a local photothermal excitation generated by a spatially localized (Ø = 2 μ m ) continuous laser beam. Interesting phenomena have been evidenced both in quasistatic and dynamic conditions (e.g., threshold effects and long incubation periods, thermal activation of the phase boundary propagation, stabilization of the crystal in a stationary biphasic state, and thermal cutoff frequency). These measurements demonstrated the importance of thermal effects in the transition dynamics, and they enabled an accurate determination of the thermal properties of the SCO compound in the framework of a simple theoretical model.

Towards traceability in CO2 line strength measurements by TDLAS at 2.7 µm

NASA Astrophysics Data System (ADS)

Pogány, Andrea; Ott, Oliver; Werhahn, Olav; Ebert, Volker

2013-11-01

Direct tunable diode laser absorption spectroscopy (TDLAS) was combined in this study with metrological principles on the determination of uncertainties to measure the line strengths of the P36e and P34e line of 12C16O2 in the ν1+ν3 band at 2.7 μm. Special emphasis was put on traceability and a concise, well-documented uncertainty assessment. We have quantitatively analyzed the uncertainty contributions of different experimental parameters to the uncertainty of the line strength. Establishment of the wavenumber axis and the gas handling procedure proved to be the two major contributors to the final uncertainty. The obtained line strengths at 296 K are 1.593×10-20 cm/molecule for the P36e and 1.981×10-20 cm/molecule for the P34e line, with relative expanded uncertainties of 1.1% and 1.3%, respectively (k=2, corresponding to a 95% confidence level). The measured line strength values are in agreement with literature data (line strengths listed in the HITRAN and GEISA databases), but show an uncertainty, which is at least a factor of 2 lower.

The influence of removing sizing on strength and stiffness of conventional and high modulus E-glass fibres

NASA Astrophysics Data System (ADS)

Nørgaard Petersen, Helga; Kusano, Yukihiro; Brøndsted, Povl; Almdal, Kristoffer

2016-07-01

Two types of E-glass fibres, a conventional and a high modulus where the last one in the following will be denoted as ECR-glass fibre, were investigated regarding density, diameter, stiffness and strength. The fibres were analysed as pristine and after sizing removal treatments. The sizing was removed by either burning at 565°C or soxhlet extraction with acetone. It was found that the density and the stiffness increased after removing the sizing by the two removal treatments whereas the diameter did not change significantly. The strength of the fibres decreased after burning as the sizing, protecting against water and fibre-fibre damage, had been removed. The strength of the fibres after extraction was not significantly different from the strength of the pristine fibres despite removing the sizing. This indicates that the bonded part of sizing is still protecting the glass fibre surface.

Finite-temperature fluid–insulator transition of strongly interacting 1D disordered bosons

PubMed Central

Michal, Vincent P.; Aleiner, Igor L.; Altshuler, Boris L.; Shlyapnikov, Georgy V.

2016-01-01

We consider the many-body localization–delocalization transition for strongly interacting one-dimensional disordered bosons and construct the full picture of finite temperature behavior of this system. This picture shows two insulator–fluid transitions at any finite temperature when varying the interaction strength. At weak interactions, an increase in the interaction strength leads to insulator → fluid transition, and, for large interactions, there is a reentrance to the insulator regime. It is feasible to experimentally verify these predictions by tuning the interaction strength with the use of Feshbach or confinement-induced resonances, for example, in 7Li or 39K. PMID:27436894

VUV Absorption Spectra of Gas-Phase Quinoline in the 3.5 - 10.7 eV Photon Energy Range.

PubMed

Leach, Sydney; Jones, Nykola C; Hoffmann, Søren Vrønning; Un, Sun

2018-06-16

The absorption spectrum of quinoline was measured in the gas phase between 3.5 and 10.7 eV using a synchrotron photon source. A large number of sharp and broad spectral features were observed, some of which have plasmon-type collective π-electron modes contributing to their intensities. Eight valence electronic transitions were assigned, considerably extending the number of π-π* transitions previously observed mainly in solution. The principal factor in solution red-shifts is found to be the Lorentz-Lorenz polarizability parameter. Rydberg bands, observed for the first time, are analysed into eight different series, converging to the D0 ground and two excited electronic states, D3 and D4, of the quinoline cation. The R1 series limit is 8.628 eV for the first ionization energy of quinoline, a value more precise than previously published. This value, combined with cation electronic transition data provides precise energies, respectively 10.623 eV and 11.355 eV, for the D3 and D4 states. The valence transition assignments are based on DFT calculations as well as on earlier Pariser-Parr-Pople SCF LCAO MO results. The relative quality of the P-P-P and DFT data is discussed. Both are far from spectroscopic accuracy concerning electronic excited states but were nevertheless useful for our assignments. Our time-dependent DFT calculations of quinoline are excellent for its ground state properties such as geometry, rotational constants, dipole moment and vibrational frequencies, which agree well with experimental observations. Vibrational components of the valence and Rydberg transitions mainly involve C-H bend and C=C and C=N stretch modes. Astrophysical applications of the VUV absorption of quinoline are briefly discussed.

Effects of In-Season Explosive Strength Training on Maximal Leg Strength, Jumping, Sprinting, and Intermittent Aerobic Performance in Male Handball Athletes.

PubMed

Hermassi, Souhail; Chelly, Mohamed Souhaiel; Fieseler, Georg; Bartels, Thomas; Schulze, Stephan; Delank, Karl-Stefan; Shephard, Roy J; Schwesig, René

2017-09-01

Background  Team handball is an intense ball sport with specific requirements on technical skills, tactical understanding, and physical performance. The ability of handball players to develop explosive efforts (e. g. sprinting, jumping, changing direction) is crucial to success. Objective  The purpose of this pilot study was to examine the effects of an in-season high-intensity strength training program on the physical performance of elite handball players. Materials and methods  Twenty-two handball players (a single national-level Tunisian team) were randomly assigned to a control group (CG; n = 10) or a training group (TG; n = 12). At the beginning of the pilot study, all subjects performed a battery of motor tests: one repetition maximum (1-RM) half-squat test, a repeated sprint test [6 × (2 × 15 m) shuttle sprints], squat jumps, counter movement jumps (CMJ), and the Yo-Yo intermittent recovery test level 1. The TG additionally performed a maximal leg strength program twice a week for 10 weeks immediately before engaging in regular handball training. Each strength training session included half-squat exercises to strengthen the lower limbs (80 - 95 % of 1-RM, 1 - 3 repetitions, 3 - 6 sets, 3 - 4 min rest between sets). The control group underwent no additional strength training. The motor test battery was repeated at the end of the study interventions. Results  In the TG, 3 parameters (maximal strength of lower limb: η² = 0.74; CMJ: η² = 0.70, and RSA best time: η² = 0.25) showed significant improvements, with large effect sizes (e. g. CMJ: d = 3.77). A reduction in performance for these same 3 parameters was observed in the CG (d = -0.24). Conclusions  The results support our hypothesis that additional strength training twice a week enhances the maximal strength of the lower limbs and jumping or repeated sprinting performance. There was no evidence of shuttle sprints ahead of regular

Phase Transitions on Surfaces. An International Conference. Abstracts and Program, 3-7 August 1981, Orono, Maine.

DTIC Science & Technology

1982-04-16

P. J. Estrup Chemisorption-Induced Phase Transitions and Adatom Interactions on GaAs(110) P. Skeath, C. Y. Su, P. W. Chye , I. Lindau and W. E. Spicer...Transitions and Adatom Interactions on GaAs(ll0)* Perry Skeath, C. Y. Su, P. W. Chye , I Lindau, and W. E. Spicer Stanford Electronics Labs Stanford...ORDER PHASE TRANSITIONS* P. KLEBAN and CHIN -KUN HU, Department of Physics and Astronomy and Laboratory for Surface Science and Technology University of

Theoretical formulation of optical conductivity of La0.7Ca0.3MnO3 exhibiting paramagnetic insulator - ferromagnetic metal transition

NASA Astrophysics Data System (ADS)

Satiawati, L.; Majidi, M. A.

2017-07-01

A theory of high-energy optical conductivity of La0.7Ca0.3MnO3 has been proposed previously. The proposed theory works to explain the temperature-dependence of the optical conductivity for the photon energy region above ˜0.5 eV for up to ˜22 eV, but fails to capture the correct physics close to the dc limit in which metal-insulator transition occurs. The missing physics at the low energy has been acknowledged as mainly due to not incorporating phonon degree of freedom and electron-phonon interactions. In this study, we aim to complete the above theory by proposing a more complete Hamiltonian incorporating additional terms such as crystal field, two modes of Jahn-Teller vibrations, and coupling between electrons and the two Jahn-Teller vibrational modes. We solve the model by means of dynamical mean-field theory. At this stage, we aim to derive the analytical formulae involved in the calculation, and formulate the algorithmic implementation for the self-consistent calculation process. Our final goal is to compute the density of states and the optical conductivity for the complete photon energy range from 0 to 22 eV at various temperatures, and compare them with the experimental data. We expect that the improved model preserves the correct temperature-dependent physics at high photon energies, as already captured by the previous model, while it would also reveal ferromagnetic metal - paramagnetic insulator transition at the dc limit.

Origin of field-induced discontinuous phase transitions in N d2F e17

NASA Astrophysics Data System (ADS)

Diop, L. V. B.; Kuz'min, M. D.; Skokov, K. P.; Skourski, Y.; Gutfleisch, O.

2018-02-01

Magnetic properties of a trigonal ferromagnet N d2F e17 have been studied on single crystals in steady (14 T) and pulsed (32 T) magnetic fields. The easy-magnetization direction lies close to the [120] axis, deviating from the basal plane by 2 .9∘ (at T =5 K ). Of particular interest is the low-temperature magnetization process along the high-symmetry axis [001], which is the hard direction. This process is discontinuous and involves two first-order phase transitions (FOMPs). One of them (at 20 T) is a symmetry FOMP similar to that observed in S m2F e17 . The second transition (at 10.4 T) is unusual: as the magnetization turns abruptly toward the applied field, it also changes its azimuthal orientation (the angle φ ) by 60∘. Both transitions can be reasonably accounted for by the presence of a significant sixth-order trigonal anisotropy term.

Lifetimes and Oscillator Strengths for Ultraviolet Transitions Involving ns2nd 2D and nsnp2 2D terms in Pb II, Sn II, and Ge II

NASA Astrophysics Data System (ADS)

Federman, Steven Robert; Heidarian, Negar; Irving, Richard; Ellis, David; Ritchey, Adam M.; Cheng, Song; Curtis, Larry; Furman, Walter

2017-06-01

Radiative transitions of heavy elements are of great importance in astrophysics. Studying the transition rates and their corresponding oscillator strengths allows us to determine abundances of these heavy elements and therefore leads to better understanding of neutron capture processes. We provide the results of our studies on the transitions involving ns2nd 2D and nsnp2 2D terms to the ground term for Pb II, Sn II, and Ge II. These transitions are also of interest due to their strong mixing. Our studies involve experimental measurements performed at the Toledo Heavy Ion Accelerator and theoretical multi-configuration Dirac Hartree-Fock (MCDHF)1 calculations using the development version of the GRASP2K package2. The results are compared with Pb II lines seen in spectra acquired with the Hubble Space Telescope and with other values available in the literature. 1 P. Jönsson et al., The Computational Atomic Structure Group (2014).2 P. Jönsson et al., Comput. Phys. Commun. 184, 2197 (2013).

Gamow-Teller strength observed in the 48Ti(n, p) 48Sc reaction: Implications for the double beta decay of 48Ca

NASA Astrophysics Data System (ADS)

Alford, W. P.; Helmer, R. L.; Abegg, R.; Celler, A.; Frekers, D.; Green, P.; Häusser, O.; Henderson, R.; Hicks, K.; Jackson, K. P.; Jeppesen, R.; Miller, C. A.; Trudel, A.; Vetterli, M.; Yen, S.; Pourang, R.; Watson, J.; Brown, B. A.; Engel, J.

1990-07-01

Cross sections for the 48Ti(n, p) reaction have been measured at angles of 0°, 6°, and 12° at an energy of 200 MeV. The measurements are compared with results of DWIA calculations to obtain estimates of transition strengths for L = 0, 1, and ⩾2 up to an excitation energy of 25 MeV. Gamow-Teller strength ( L = 0) is peaked between 3 and 4 MeV excitation energy, with a significant distribution extending to about 12 MeV. The L = 1 strength is found mainly between 6 and 20 MeV while the cross section for transitions with L ⩾2 increases from 10 MeV to the upper limit of the measurements. The distribution of Gamow-Teller strength is in poor agreement with theoretical distributions used to calculate the lifetime for double beta decay of 48Ca.

Investigations of the valence-shell excitations of molecular ethane by high-energy electron scattering

NASA Astrophysics Data System (ADS)

Xu, Wei-Qing; Xu, Long-Quan; Qi, De-Guang; Chen, Tao; Liu, Ya-Wei; Zhu, Lin-Fan

2018-04-01

The differential cross sections and generalized oscillator strengths for the low-lying excitations of the valence-shell 1eg orbital electron in ethane have been measured for the first time at a high incident electron energy of 1500 eV and a scattering angular range of 1.5°-10°. A weak feature, termed X here, with a band center of about 7.5 eV has been observed, which was also announced by the previous experimental and theoretical studies. The dynamic behaviors of the generalized oscillator strengths for the 3s (8.7 eV), 3s+3p (9.31 eV, 9.41 eV), and X (˜7.5 eV) transitions on the momentum transfer squared have been obtained. The integral cross sections of these transitions from their thresholds to 5000 eV have been obtained with the aid of the BE-scaling (B is the binding energy and E is the excitation energy) method. The optical oscillator strengths of the above transitions determined by extrapolating their generalized oscillator strengths to the limit of the squared momentum transfer K2 → 0 are in good agreement with the ones from the photoabsorption spectrum [J. W. Au et al., Chem. Phys. 173, 209 (1993)], which indicates that the present differential cross sections, generalized oscillator strengths, and integral cross sections can serve as benchmark data.

Electron excitation cross sections for the 2s(2)2p(3)4S(O) -- 2s(2)2p(3)2D(O) (forbidden) and 4S(O) -- 2s2p(4) 4P (resonance) transitions in O II

NASA Technical Reports Server (NTRS)

Zuo, M.; Smith, Steven J.; Chutjian, A.; Williams, I. D.; Tayal, S. S.; Mclaughlin, Brendan M.

1995-01-01

Experimental and theoretical excitation cross sections are reported for the first forbidden transition 4S(O) -- 2S(2)2p(3) 2D(O) (lambda-lambda 3726, 3729) and the first allowed (resonance) transition 4S(O) -- 2s2p(4) 4P(lambda-833) in O II. Use is made of electron energy loss and merged-beams methods. The electron energy range covered is 3.33 (threshold) to 15 eV for the S -- D transition, and 14.9 (threshold) to 40 eV for the S -- P transition. Care was taken to assess and minimize the metastable fraction of the O II beam. An electron mirror was designed and tested to reflect inelastically backscattered electrons into the forward direction to account for the full range of polar scattering angles. Comparisons are made between present experiments and 11-state R-matrix calculations. Calculations are also presented for the 4S(O) -- 2s(2)2p(3)2P(O) (lambda-2470) transition.

Relative Ball 3X-VSR reactivity strength DR reactor. Interim Report of PT IP-126-C

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

Simpson, D.E.

1959-06-01

Prior to this experiment, no measurements of Ball 3X effectiveness had been performed for any of the older 2004-tube Hanford piles, and calculations concerning total control requirements were made assuming the vertical safety system strength equal to the strength of the B, D, F vertical safety rods. With current and projected enrichment loadings, the vertical control system was calculated to be inadequate to satisfy the total control criteria at all times, resulting in the necessity to provide supplementary control in the form of horizontal rods or temporary process tube poison. Because of the larger ball channels at DR, the Ballmore » 3X system is stronger than at the other 29-VSR piles. Therefore, the potential relaxation of total control limits was greater for DR should an experiment show the Ball 3X strength to be significantly greater than the B, D, F VSR strength. PT-IP-126-C authorized an experiment to determine the Ball 3X effectiveness at DR Pile by measurement of the relative strength of a VSR and a column of 3X balls in the same channel. The experiment was performed in March, 1958, and on the strength of favorable results a supplement to the PT was prepared to authorize the same test at one of the other 29-VSR piles. This supplement has not been approved; therefore, the results of the DR test are being reported separately in this document.« less

High doses of vitamin C plus E reduce strength training-induced improvements in areal bone mineral density in elderly men.

PubMed

Stunes, Astrid Kamilla; Syversen, Unni; Berntsen, Sveinung; Paulsen, Gøran; Stea, Tonje H; Hetlelid, Ken J; Lohne-Seiler, Hilde; Mosti, Mats Peder; Bjørnsen, Thomas; Raastad, Truls; Haugeberg, Glenn

2017-06-01

Resistance training is beneficial for maintaining bone mass. We aimed to investigate the skeletal effects of high doses of antioxidants [vitamin C + E (α-tocopherol)] supplementation during 12-week supervised strength training in healthy, elderly men METHODS: Design: double-blinded randomized placebo-controlled study. Participants followed a supervised, undulating periodic exercise program with weekly adjusted load: 3 sessions/week and 3-15 repetitions maximum (RM) sets/exercise. The control group (CG, n = 17, 67 ± 5 years) received placebo and the antioxidant group (AO, n = 16, 70 ± 7 years) 1000 mg vitamin C + 235 mg vitamin E, daily. Areal bone mineral density (aBMD) at whole body, lumbar spine (L1-L4), total hip, and femoral neck were measured by dual energy X-ray absorptiometry and muscle strength by 1RM. Serum analyses of bone-related factors and adipokines were performed. In the CG, total hip aBMD increased by 1.0% (CI: 0.3-1.7) versus pretest and lumbar spine aBMD increased by 0.9% (CI: -0.2 to 2.0) compared to the AO. In the CG, there was an increase in serum concentrations of insulin-like growth factor 1 [+27.3% (CI: -0.3 to 54.9)] and leptin [+31.2% (CI: 9.8-52.6)) versus pretest, and a decrease in sclerostin [-9.9% (CI: 4.4-15.3)] versus pretest and versus AO. Serum bone formation markers P1NP and osteocalcin increased in both groups, while the bone resorption marker CTX-1 remained unchanged. High doses of antioxidant supplementations may constrain the favorable skeletal benefits of 12 weeks of resistance exercise in healthy elderly men.

Complementary Strategies for Directed C(sp3 )-H Functionalization: A Comparison of Transition-Metal-Catalyzed Activation, Hydrogen Atom Transfer, and Carbene/Nitrene Transfer.

PubMed

Chu, John C K; Rovis, Tomislav

2018-01-02

The functionalization of C(sp 3 )-H bonds streamlines chemical synthesis by allowing the use of simple molecules and providing novel synthetic disconnections. Intensive recent efforts in the development of new reactions based on C-H functionalization have led to its wider adoption across a range of research areas. This Review discusses the strengths and weaknesses of three main approaches: transition-metal-catalyzed C-H activation, 1,n-hydrogen atom transfer, and transition-metal-catalyzed carbene/nitrene transfer, for the directed functionalization of unactivated C(sp 3 )-H bonds. For each strategy, the scope, the reactivity of different C-H bonds, the position of the reacting C-H bonds relative to the directing group, and stereochemical outcomes are illustrated with examples in the literature. The aim of this Review is to provide guidance for the use of C-H functionalization reactions and inspire future research in this area. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pressureless sintered beta prime-Si3N4 solid solution: Fabrication, microstructure, and strength

NASA Technical Reports Server (NTRS)

Dutta, S.

1977-01-01

Si3N4, AlN, and Al2O3 were used as basic constituents in a study of the pressureless sintering of beta prime-Si3N4 solid solution as a function of temperature. Y2O3-SiO2 additions were used to promote liquid-phase sintering. The sintered specimens were characterized with respect to density, microstructure, strength, oxidation, and thermal shock resistance. Density greater than 98 percent of theoretical was achieved by pressureless sintering at 1750 C. The microstructure consisted essentially of fine-grained beta prime-Si3N4 solid solution as the major phase. Modulus of rupture strengths up to 483 MPa were achieved at moderate temperature (1000 C), but decreased to 228 MPa at 1380 C. This substantial strength loss was attributed to a glassy grain boundary phase formed during cooling from the sintering temperature. The best oxidation resistance was exhibited by a composition containing 3 mol % Y2O3-SiO2 additives. Water quench thermal shock resistance was equivalent to that of reaction sintered silicon nitride but lower than hot-pressed silicon nitride.

Successive magnetic phase transitions in α -RuCl3 : XY-like frustrated magnet on the honeycomb lattice

NASA Astrophysics Data System (ADS)

Kubota, Yumi; Tanaka, Hidekazu; Ono, Toshio; Narumi, Yasuo; Kindo, Koichi

2015-03-01

The layered compound α -RuCl3 is composed of a honeycomb lattice of magnetic Ru3 + ions with the 4 d5 electronic state. We have investigated the magnetic properties of α -RuCl3 via magnetization and specific heat measurements using single crystals. It was observed that α -RuCl3 undergoes a structural phase transition at Tt≃150 K accompanied by fairly large hysteresis. This structural phase transition is expected to be similar to that observed in closely related CrCl3. The magnetizations and magnetic susceptibilities are strongly anisotropic, which mainly arise from the anisotropic g factors, i.e., ga b≃2.5 and gc≃0.4 for magnetic fields parallel and perpendicular to the a b plane, respectively. These g factors and the obtained entropy indicate that the effective spin of Ru3 + is one-half, which results from the low-spin state. Specific heat data show that magnetic ordering occurs in four steps at zero magnetic field. The successive magnetic phase transitions should be ascribed to the competition among exchange interactions. The magnetic phase diagram for H ∥a b is obtained. We discuss the strongly anisotropic g factors in α -RuCl3 and deduce that the exchange interaction is strongly XY-like. α -RuCl3 is magnetically described as a three-dimensionally coupled XY-like frustrated magnet on a honeycomb lattice.

[Structure and luminescence properties of Ga2O3 : Cr3+ by Al doping].

PubMed

Wang, Xian-Sheng; Wan, Min-Hua; Wang, Yin-Hai; Zhao, Hui; Hu, Zheng-Fa; Li, Hai-Ling

2013-11-01

The Al doping gallate phosphor (Ga(1-x)Al(x))2O3 : Cr3+ (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) was synthesized by a high temperature solid-state reaction method. The X-ray diffractions show that the phase of the phosphors remains to be Ga2 O3 structure with increase in the contents of Al3+ ion. Beside, the fact that the X-ray diffraction peak shifts towards big angles with increasing Al3+ ions content shows that Al3+ ions entered the Ga2 O3 lattice. The peaks of the excitation spectra located at 258, 300, 410 and 550 nm are attributed to the band to band transition of the matrix, charge transfer band transition, and 4A2 --> 4T1 and 4A2 --> 4T2 transition of Cr3+ ions, respectively. Those excitation spectrum peak positions show different degrees of blue shift with the increase in the Al3+ ions content. The blue shift of the first two peaks are due to the band gap energy of substrate and the electronegativity between Cr3+ ions and ligands increasing, respectively. The blue shift of the energy level transition of Cr3+ ion is attributed to crystal field strength increasing. The Cr3+ ion luminescence changes from a broadband emission to a narrow-band emission with Al3+ doping, because the emission of Cr3+ ion changed from 4 T2 --> 4A2 to 2E --> 4A2 transition with the crystal field change after Al3+ ions doping. The Al3+ ions doping improved the long afterglow luminescence properties of samples, and the sample showed a longer visible near infrared when Al3+ ions content reaches 0.5. The thermoluminescence curve shows the sample with suitable trap energy level, and this is also the cause of the long afterglow luminescence materials.

Phase transition in 2-d system of quadrupoles on square lattice with anisotropic field

NASA Astrophysics Data System (ADS)

Sallabi, A. K.; Alkhttab, M.

2014-12-01

Monte Carlo method is used to study a simple model of two-dimensional interacting quadrupoles on ionic square lattice with anisotropic strength provided by the ionic lattice. Order parameter, susceptibility and correlation function data, show that this system form an ordered structure with p(2×1) symmetry at low temperature. The p(2×1) structure undergoes an order-disorder phase transition into disordered (1×1) phase at 8.3K. The two-point correlation function show exponential dependence on distance both above and below the transition temperature. At Tc the two-point correlation function shows a power law dependence on distance, e.g. C(r) ~ 1η. The value of the exponent η at Tc shows small deviation from the Ising value and indicates that this system falls into the same universality class as the XY model with cubic anisotropy. This model can be applied to prototypical quadrupoles physisorbed systems as N2 on NaCl(100).

Strength testing and training of rowers: a review.

PubMed

Lawton, Trent W; Cronin, John B; McGuigan, Michael R

2011-05-01

In the quest to maximize average propulsive stroke impulses over 2000-m racing, testing and training of various strength parameters have been incorporated into the physical conditioning plans of rowers. Thus, the purpose of this review was 2-fold: to identify strength tests that were reliable and valid correlates (predictors) of rowing performance; and, to establish the benefits gained when strength training was integrated into the physical preparation plans of rowers. The reliability of maximal strength and power tests involving leg extension (e.g. leg pressing) and arm pulling (e.g. prone bench pull) was high (intra-class correlations 0.82-0.99), revealing that elite rowers were significantly stronger than their less competitive peers. The greater strength of elite rowers was in part attributed to the correlation between strength and greater lean body mass (r = 0.57-0.63). Dynamic lower body strength tests that determined the maximal external load for a one-repetition maximum (1RM) leg press (kg), isokinetic leg extension peak force (N) or leg press peak power (W) proved to be moderately to strongly associated with 2000-m ergometer times (r = -0.54 to -0.68; p < 0.05). Repetition tests that assess muscular or strength endurance by quantifying the number of repetitions accrued at a fixed percentage of the strength maximum (e.g. 50-70% 1RM leg press) or set absolute load (e.g. 40 kg prone bench pulls) were less reliable and more time consuming when compared with briefer maximal strength tests. Only leg press repetition tests were correlated with 2000-m ergometer times (e.g. r = -0.67; p < 0.05). However, these tests differentiate training experience and muscle morphology, in that those individuals with greater training experience and/or proportions of slow twitch fibres performed more repetitions. Muscle balance ratios derived from strength data (e.g. hamstring-quadriceps ratio <45% or knee extensor-elbow flexor ratio around 4.2 ± 0.22 to

Refrigeration of the 18.3 GHz C_3H_2 Transition in Dark Clouds G1.6-0.25

NASA Technical Reports Server (NTRS)

Kuiper, T. B. H.; Whiteoak, J. B.; Peng, R. -S.; Peters, W. L., III; Reynolds, J. E.

1993-01-01

We have observed the 1_(10)-1_(01) (18.3 GHz) transition of orthocyclopropenylidene, C_(-3)H_(-2), at 24 positions in the unusual dense cloud G1.6- 0.025. Except for one position, the transition is refrigerated, a phenomenon which has not been seen in this transition before.

Fast-timing lifetime measurement of 152Gd

NASA Astrophysics Data System (ADS)

Wiederhold, J.; Kern, R.; Lizarazo, C.; Pietralla, N.; Werner, V.; Jolos, R. V.; Bucurescu, D.; Florea, N.; Ghita, D.; Glodariu, T.; Lica, R.; Marginean, N.; Marginean, R.; Mihai, C.; Mihai, R.; Mitu, I. O.; Negret, A.; Nita, C.; Olacel, A.; Pascu, S.; Stroe, L.; Toma, S.; Turturica, A.

2016-10-01

The lifetime τ (02+) of 152Gd has been measured using fast electronic scintillation timing (FEST) with an array of high-purity germanium (HPGe) and cerium-doped lanthanum bromide (LaBr3) detectors. 152Gd was produced via an (α ,n ) reaction on a gold backed 149Sm target. The measured lifetime of τ (02+) =96 (6 ) ps corresponds to a reduced transition strength of B (E 2 ;02+→21+) =111 (7 ) W.u. and an E 0 transition strength of ρ2(E 0 ) =39 (3 ) ×10-3 to the ground state. This result provides experimental support for the validity of a correlation that would be a novel indicator for a quantum phase transition (QPT).

The strength and rheology of methane clathrate hydrate

USGS Publications Warehouse

Durham, W.B.; Kirby, S.H.; Stern, L.A.; Zhang, W.

2003-01-01

Methane clathrate hydrate (structure I) is found to be very strong, based on laboratory triaxial deformation experiments we have carried out on samples of synthetic, high-purity, polycrystalline material. Samples were deformed in compressional creep tests (i.e., constant applied stress, ??), at conditions of confining pressure P = 50 and 100 MPa, strain rate 4.5 ?? 10-8 ??? ?? ??? 4.3 ?? 10-4 s-1, temperature 260 ??? T ??? 287 K, and internal methane pressure 10 ??? PCH4 ??? 15 MPa. At steady state, typically reached in a few percent strain, methane hydrate exhibited strength that was far higher than expected on the basis of published work. In terms of the standard high-temperature creep law, ?? = A??ne-(E*+PV*)/RT the rheology is described by the constants A = 108.55 MPa-n s-1, n = 2.2, E* = 90,000 J mol-1, and V* = 19 cm3 mol-1. For comparison at temperatures just below the ice point, methane hydrate at a given strain rate is over 20 times stronger than ice, and the contrast increases at lower temperatures. The possible occurrence of syntectonic dissociation of methane hydrate to methane plus free water in these experiments suggests that the high strength measured here may be only a lower bound. On Earth, high strength in hydrate-bearing formations implies higher energy release upon decomposition and subsequent failure. In the outer solar system, if Titan has a 100-km-thick near-surface layer of high-strength, low-thermal conductivity methane hydrate as has been suggested, its interior is likely to be considerably warmer than previously expected.

Spatio-temporal transitions in the dynamics of bacterial populations

NASA Astrophysics Data System (ADS)

Lin, Anna; Lincoln, Bryan; Mann, Bernward; Torres, Gelsy; Kas, Josef; Swinney, Harry

2001-03-01

We experimentally investigate the population dynamics of a strain of E. coli bacteria living under spatially inhomogeneous growth conditions. A localized perturbation that moves with a well-defined drift velocity is imposed on the system. A reaction-diffusion model of this situation^1 predicts that an abrupt transition between spatial localization and extinction of the colony occurs for a fixed average growth rate when the drift velocity exceeds a critical value. Also, a transition between localized and delocalized populations is predicted to occur at a fixed drift velocity when the spatially averaged growth rate is varied. We create a spatially localized perturbation with UV light and vary the strength and drift velocity of the perturbation to investigate the existence of the different bacterial population distributions and the transitions between them. Numerical simulations of a 250 mm by 20 mm system guide our experiments. ^1K. A. Dahmen, D. R. Nelson, N. M. Shnerb, Jour. Math. Bio., 41 1 (2000).

Two-photon-absorption line strengths for nitric oxide: Comparison of theory and sub-Doppler, laser-induced fluorescence measurements

NASA Astrophysics Data System (ADS)

Kulatilaka, Waruna D.; Lucht, Robert P.

2017-03-01

We discuss the results of high-resolution, sub-Doppler two-photon-absorption laser-induced fluorescence (TPALIF) spectroscopy of nitric oxide at low pressure and room temperature. The measurements were performed using the single-longitudinal mode output of a diode-laser-seeded optical parametric generator (OPG) system with a measured frequency bandwidth of 220 MHz. The measurements were performed using a counter-propagating pump beam geometry, resulting in sub-Doppler TPALIF spectra of NO for various rotational transitions in the (0,0) vibrational band of the A2Σ+ - X2Π electronic transition. The experimental results are compared with the results of a perturbative treatment of the rotational line strengths for the 20 different rotational branches of the X2Π(v″ = 0) → A2Σ+(v' = 0) two-photon absorption band. In the derivation of the expressions for the two-photon transition absorption strength, the closure relation is used for rotational states in the intermediate levels of the two-photon transition in analogy with the Placzek treatment of Raman transitions. The theoretical treatment of the effect of angular momentum coupling on the two-photon rotational line strengths features the use of irreducible spherical tensors and 3j symbols. The final results are expressed in terms of the Hund's case (a) coupling coefficients aJ and bJ for the X2Π(v″ = 0) rotational level wavefunctions, which are intermediate between Hund's case (a) and case (b). Considerable physical insight is provided by this final form of the equations for the rotational line strengths. Corrections to the two-photon absorption rotational line strength for higher order effects such as centrifugal stretching can be included in a straightforward fashion in the analysis by incorporating higher order terms in these coupling coefficients aJ and bJ, although these corrections are essentially negligible for J < 50. The theoretical calculations of relative line intensities are in good agreement both

Dimensionality-Driven Metal-Insulator Transition in Spin-Orbit-Coupled SrIrO3

NASA Astrophysics Data System (ADS)

Schütz, P.; Di Sante, D.; Dudy, L.; Gabel, J.; Stübinger, M.; Kamp, M.; Huang, Y.; Capone, M.; Husanu, M.-A.; Strocov, V. N.; Sangiovanni, G.; Sing, M.; Claessen, R.

2017-12-01

Upon reduction of the film thickness we observe a metal-insulator transition in epitaxially stabilized, spin-orbit-coupled SrIrO3 ultrathin films. By comparison of the experimental electronic dispersions with density functional theory at various levels of complexity we identify the leading microscopic mechanisms, i.e., a dimensionality-induced readjustment of octahedral rotations, magnetism, and electronic correlations. The astonishing resemblance of the band structure in the two-dimensional limit to that of bulk Sr2 IrO4 opens new avenues to unconventional superconductivity by "clean" electron doping through electric field gating.

Precision measurement of the electromagnetic dipole strengths in Be11

NASA Astrophysics Data System (ADS)

Kwan, E.; Wu, C. Y.; Summers, N. C.; Hackman, G.; Drake, T. E.; Andreoiu, C.; Ashley, R.; Ball, G. C.; Bender, P. C.; Boston, A. J.; Boston, H. C.; Chester, A.; Close, A.; Cline, D.; Cross, D. S.; Dunlop, R.; Finlay, A.; Garnsworthy, A. B.; Hayes, A. B.; Laffoley, A. T.; Nano, T.; Navrátil, P.; Pearson, C. J.; Pore, J.; Quaglioni, S.; Svensson, C. E.; Starosta, K.; Thompson, I. J.; Voss, P.; Williams, S. J.; Wang, Z. M.

2014-05-01

The electromagnetic dipole strength in Be11 between the bound states has been measured using low-energy projectile Coulomb excitation at bombarding energies of 1.73 and 2.09 MeV/nucleon on a Pt196 target. An electric dipole transition probability B(E1;1/2-→1/2+)=0.102(2) e2fm was determined using the semi-classical code Gosia, and a value of 0.098(4) e2fm was determined using the Extended Continuum Discretized Coupled Channels method with the quantum mechanical code FRESCO. These extracted B(E1) values are consistent with the average value determined by a model-dependent analysis of intermediate energy Coulomb excitation measurements and are approximately 14% lower than that determined by a lifetime measurement. The much-improved precisions of 2% and 4% in the measured B(E1) values between the bound states deduced using Gosia and the Extended Continuum Discretized Coupled Channels method, respectively, compared to the previous accuracy of ˜10% will help in our understanding of and better improve the realistic inter-nucleon interactions.

9 CFR 3.39 - Care in transit.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Pigs and Hamsters Transportation Standards § 3.39 Care in transit. (a) During surface transportation... pigs or hamsters as frequently as circumstances may dictate, but not less than once every 4 hours, to... any of the live guinea pigs or hamsters are in obvious physical distress and to provide any needed...

9 CFR 3.39 - Care in transit.

Code of Federal Regulations, 2014 CFR

2014-01-01

... Pigs and Hamsters Transportation Standards § 3.39 Care in transit. (a) During surface transportation... pigs or hamsters as frequently as circumstances may dictate, but not less than once every 4 hours, to... any of the live guinea pigs or hamsters are in obvious physical distress and to provide any needed...

9 CFR 3.39 - Care in transit.

Code of Federal Regulations, 2012 CFR

2012-01-01

... Pigs and Hamsters Transportation Standards § 3.39 Care in transit. (a) During surface transportation... pigs or hamsters as frequently as circumstances may dictate, but not less than once every 4 hours, to... any of the live guinea pigs or hamsters are in obvious physical distress and to provide any needed...

9 CFR 3.39 - Care in transit.

Code of Federal Regulations, 2013 CFR

2013-01-01

... Pigs and Hamsters Transportation Standards § 3.39 Care in transit. (a) During surface transportation... pigs or hamsters as frequently as circumstances may dictate, but not less than once every 4 hours, to... any of the live guinea pigs or hamsters are in obvious physical distress and to provide any needed...

A novel chitosan-tussah silk fibroin/nano-hydroxyapatite composite bone scaffold platform with tunable mechanical strength in a wide range.

PubMed

Ran, Jiabing; Hu, Jingxiao; Sun, Guanglin; Chen, Si; Jiang, Pei; Shen, Xinyu; Tong, Hua

2016-12-01

Currently, great efforts have been made to enhance the mechanical strength of bone tissue engineering (BTE) scaffolds, which are composed of biopolymeric matrices and inorganic nano-fillers. But the tunability of mechanical strength in a wide range for BTE scaffolds has seldom been investigated in spite of the great importance of this performance. In this work, a chitosan-tussah silk fibroin/hydroxyapatite (CS-TSF/HAp) hydrogel was synthesized by using a novel in situ precipitation method. Through in situ inducing the conformation transition of TSF in the CS-TSF/HAp hydrogel, which could be monitored by XRD, FT-IR, TGA, and DTA, the elastic modulus and fracture strength of the final CS-TSF/HAp composite could be tailored in a wide range without changing its composition, morphology, roughness, and crystal structures. The elastic modulus of the CS-TSF/HAp composite ranged from ∼250 to ∼400MPa while its fracture strength ranged from ∼45 to ∼100MPa. In order to clarify the rationale behind this process, a speculative explanation was provided. In vitro cell culture indicated that MC3T3-E1 cells cultured on the CS-TSF/HAp composite had positive adhesion, proliferation, and differentiation potential. We believed that the CS-TSF/HAp composite could be used as an ideal scaffold platform for cell culture and implantation of bone reconstruction. Copyright © 2016 Elsevier B.V. All rights reserved.

Consequences of acid strength for isomerization and elimination catalysis on solid acids.

PubMed

Macht, Josef; Carr, Robert T; Iglesia, Enrique

2009-05-13

We address here the manner in which acid catalysis senses the strength of solid acids. Acid strengths for Keggin polyoxometalate (POM) clusters and zeolites, chosen because of their accurately known structures, are described rigorously by their deprotonation energies (DPE). Mechanistic interpretations of the measured dynamics of alkane isomerization and alkanol dehydration are used to obtain rate and equilibrium constants and energies for intermediates and transition states and to relate them to acid strength. n-Hexane isomerization rates were limited by isomerization of alkoxide intermediates on bifunctional metal-acid mixtures designed to maintain alkane-alkene equilibrium. Isomerization rate constants were normalized by the number of accessible protons, measured by titration with 2,6-di-tert-butylpyridine during catalysis. Equilibrium constants for alkoxides formed by protonation of n-hexene increased slightly with deprotonation energies (DPE), while isomerization rate constants decreased and activation barriers increased with increasing DPE, as also shown for alkanol dehydration reactions. These trends are consistent with thermochemical analyses of the transition states involved in isomerization and elimination steps. For all reactions, barriers increased by less than the concomitant increase in DPE upon changes in composition, because electrostatic stabilization of ion-pairs at the relevant transition states becomes more effective for weaker acids, as a result of their higher charge density at the anionic conjugate base. Alkoxide isomerization barriers were more sensitive to DPE than for elimination from H-bonded alkanols, the step that limits 2-butanol and 1-butanol dehydration rates; the latter two reactions showed similar DPE sensitivities, despite significant differences in their rates and activation barriers, indicating that slower reactions are not necessarily more sensitive to acid strength, but instead reflect the involvement of more unstable organic

Revisiting ρ1 Cancri e: A New Mass Determination of the Transiting Super-Earth

NASA Astrophysics Data System (ADS)

Endl, Michael; Robertson, Paul; Cochran, William D.; MacQueen, Phillip J.; Brugamyer, Erik J.; Caldwell, Caroline; Wittenmyer, Robert A.; Barnes, Stuart I.; Gullikson, Kevin

2012-11-01

We present a mass determination for the transiting super-Earth ρ1 Cancri e based on nearly 700 precise radial velocity (RV) measurements. This extensive RV data set consists of data collected by the McDonald Observatory planet search and published data from Lick and Keck observatories. We obtained 212 RV measurements with the Tull Coudé Spectrograph at the Harlan J. Smith 2.7 m Telescope and combined them with a new Doppler reduction of the 131 spectra that we have taken in 2003-2004 with the High-Resolution Spectrograph (HRS) at the Hobby-Eberly Telescope for the original discovery of ρ1 Cancri e. Using this large data set we obtain a five-planet Keplerian orbital solution for the system and measure an RV semi-amplitude of K = 6.29 ± 0.21 m s-1 for ρ1 Cnc e and determine a mass of 8.37 ± 0.38 M ⊕. The uncertainty in mass is thus less than 5%. This planet was previously found to transit its parent star, which allowed them to estimate its radius. Combined with the latest radius estimate from Gillon et al., we obtain a mean density of ρ = 4.50 ± 0.20 g cm-3. The location of ρ1 Cnc e in the mass-radius diagram suggests that the planet contains a significant amount of volatiles, possibly a water-rich envelope surrounding a rocky core. Based partly on observations obtained with the Hobby-Eberly Telescope, which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen.

Repeatability and Reproducibility of Compression Strength Measurements Conducted According to ASTM E9

NASA Technical Reports Server (NTRS)

Luecke, William E.; Ma, Li; Graham, Stephen M.; Adler, Matthew A.

2010-01-01

Ten commercial laboratories participated in an interlaboratory study to establish the repeatability and reproducibility of compression strength tests conducted according to ASTM International Standard Test Method E9. The test employed a cylindrical aluminum AA2024-T351 test specimen. Participants measured elastic modulus and 0.2 % offset yield strength, YS(0.2 % offset), using an extensometer attached to the specimen. The repeatability and reproducibility of the yield strength measurement, expressed as coefficient of variations were cv(sub r)= 0.011 and cv(sub R)= 0.020 The reproducibility of the test across the laboratories was among the best that has been reported for uniaxial tests. The reported data indicated that using diametrically opposed extensometers, instead of a single extensometer doubled the precision of the test method. Laboratories that did not lubricate the ends of the specimen measured yield stresses and elastic moduli that were smaller than those measured in laboratories that lubricated the specimen ends. A finite element analysis of the test specimen deformation for frictionless and perfect friction could not explain the discrepancy, however. The modulus measured from stress-strain data were reanalyzed using a technique that finds the optimal fit range, and applies several quality checks to the data. The error in modulus measurements from stress-strain curves generally increased as the fit range decreased to less than 40 % of the stress range.

Bond-length fluctuations and the spin-state transition in LCoO3 (L=La, Pr, and Nd)

NASA Astrophysics Data System (ADS)

Yan, J.-Q.; Zhou, J.-S.; Goodenough, J. B.

2004-04-01

The temperature dependence of thermal conductivity, κ(T), and magnetic susceptibility, χ(T), have been measured on single crystals of LCoO3 (L=La, Pr, Nd) grown by the floating-zone method. The susceptibility measurement shows a progressive stabilization of the low-spin (LS) state of Co(III) with decreasing size of the L3+ ion, and the population of excited intermediate-spin (IS) or high-spin (HS) state Co(III) ions begins to increase at 200 K and 300 K for PrCoO3 and NdCoO3 compared with 35 K in LaCoO3. The low-temperature Curie-Weiss paramagnetic susceptibility of LCoO3 is an intrinsic property arising from surface cobalt and, possibly, a LS ground state bearing some IS character caused by the virtual excitation to the IS state. The transition from a LS to a IS/HS state introduces bond-length fluctuations that suppress the phonon contribution to κ(T) below 300 K. The suppressed κ(T) could be further reduced by dynamic Jahn-Teller distortions associated with the IS/HS species. A smooth transition in ρ(T) and α(T) and a nearly temperature independent α(T)≈20 μV/K above 600 K do not support a thermally induced, homogeneous Mott-Hubbard transition model for the high-temperature transition of LaCoO3 from an insulating to a conductive state. A two-phase process is proposed for the interval 300 Ke electrons that are stabilized by Jahn-Teller distortions that may be dynamic.

[In vitro study on shear bond strength of veneering ceramics to zirconia].

PubMed

Hu, Xiaoping; Zhu, Hongshui; Zeng, Liwei

2012-12-01

To investigate the shear bond strength between veneering ceramic and zirconia core in different all-ceramic systems. Twenty disk-shaped specimens with 8 mm in diameter and 3 mm in height for each zirconia system (Lava, Cercon, IPS e.max ZirCAD, Procera) were fabricated respectively and divided into four groups: Lava group, Cercon group, IPS e.max ZirCAD group, Procera group. For each group, 10 specimens were sintered with 1 mm corresponding veneering ceramic, while the other were sintered with 2 mm corresponding veneering ceramic respectively. The shear bond strength and fracture mode of specimens were observed and determined. The values of shear bond strength for Lava, Cercon, IPS e.max ZirCAD and Procera were (13.82 +/- 3.71), (13.24 +/- 2.09), (6.37 +/- 4.15), (5.19 +/- 5.31) MPa in the group of 1 mm thicked veneering ceramics, respectively, while the values in the group of 2mm thicked veneering ceramics were (38.77 +/- 1.69), (21.67 +/- 3.34), (12.70 +/- 4.24), (9.94 +/- 6.67) MPa. The values of Lava and Cercon groups were significantly higher than that of IPS e.max ZirCAD and Procera groups (P < 0.05). And the values of 2 mm thicked veneering ceramic group were significantly higher than that in 1 mm thicked groups (P < 0.05). Adhesive fracture between core and veneering ceramics were observed in the fracture modes of most specimens. The shear bond strength of veneering ceramic to the zirconia framework are different from the zirconia system we chose, and the thickness of veneering ceramic has a great impact on its shear bond strength.

P/M Processing of Rare Earth Modified High Strength Steels.

DTIC Science & Technology

1980-12-01

AA094 165 TRW INC CLEVELAND OH MATERIALS TECHNOLOGY F 6 P/N PROCESSING OF RARE EARTH MODIFIED HIGH STRENGTH STEELS DEC So A A SHEXM(ER NOOŕT76-C...LEVEL’ (7 PIM PROCESSING OF RARE EARTH MODIFIED HIGH STRENGTH STEELS By A. A. SHEINKER 00 TECHNICAL REPORT Prepared for Office of Naval Research...Processing of Rare Earth Modified High 1 Technical -’ 3t eC"Strength Steels * 1dc4,093Se~ 9PEFRIGOGNZTONAEADADDRESS 10. PROGRAM ELEMENT. PROJECT. TASK

E-Mobility and the Energy Transition.

PubMed

Schlögl, Robert

2017-09-04

Since the reduction of greenhouse gases is the top priority of the Energy Transition, primary electricity should be converted to material energy carriers. In this way electricity can be "stored" and made accessible for other applications. This Essay focuses on the integration of mobility in the Energy Transition and the development of sustainable alternatives to electricity-based transportation. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

47 CFR 5.87 - Frequencies for field strength surveys or equipment demonstrations.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 47 Telecommunication 1 2012-10-01 2012-10-01 false Frequencies for field strength surveys or... EXPERIMENTAL RADIO SERVICE (OTHER THAN BROADCAST) Applications and Licenses § 5.87 Frequencies for field strength surveys or equipment demonstrations. (a) Authorizations issued under §§ 5.3 (e) and (f) of this...

47 CFR 5.87 - Frequencies for field strength surveys or equipment demonstrations.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 1 2010-10-01 2010-10-01 false Frequencies for field strength surveys or... EXPERIMENTAL RADIO SERVICE (OTHER THAN BROADCAST) Applications and Licenses § 5.87 Frequencies for field strength surveys or equipment demonstrations. (a) Authorizations issued under §§ 5.3 (e) and (f) of this...

47 CFR 5.87 - Frequencies for field strength surveys or equipment demonstrations.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 1 2011-10-01 2011-10-01 false Frequencies for field strength surveys or... EXPERIMENTAL RADIO SERVICE (OTHER THAN BROADCAST) Applications and Licenses § 5.87 Frequencies for field strength surveys or equipment demonstrations. (a) Authorizations issued under §§ 5.3 (e) and (f) of this...

Effect of ACTN3 gene on strength and endurance in soccer players.

PubMed

Pimenta, Eduardo M; Coelho, Daniel B; Veneroso, Christiano E; Barros Coelho, Ering J; Cruz, Izinara R; Morandi, Rodrigo F; De A Pussieldi, Guilherme; Carvalho, Maria R S; Garcia, Emerson S; De Paz Fernández, José A

2013-12-01

Sports efficiency in activities in which strength and speed are the determining factors has been associated to the ACTN3 gene, which is responsible for the expression of α-actinin-3. Soccer is a mainly aerobic sport because of its long duration, but the acute actions that define the game demand a lot of strength and speed. The purpose of the present study was to compare the performance capacity of soccer players with different genotype groups of ACTN3 (XX, RX, and RR) in strength, speed, and endurance tests. Two hundred professional players of Brazilian soccer first division teams participated in this study. Speed, jump, and endurance test results were compared with the polymorphisms of the ACTN3 gene. It was noticed that RR individuals spent less time to run a 10-m path, compared with XX individuals (p < 0.05). The RR individuals also presented lower time rates at the 20- and 30-m path, compared with RX and XX individuals (p < 0.05). In jump tests, RR individuals presented higher rates, compared with RX and XX individuals (p < 0.05). As for aerobic tests, the XX individuals presented higher rates of V[Combining Dot Above]O2 max, compared with the RR group (p < 0.05), and did not differ from the RX group. The main conclusion of this study is that soccer players of genotype ACTN3/RR are the fastest in short distances and present higher jump potential. ACTN3/XX individuals presented the highest aerobic capacity. These findings can be used in training load adjustment and can influence the development of tactical schemes in soccer matches.

Multifunctional Beta Ti Alloy with Improved Specific Strength

NASA Astrophysics Data System (ADS)

Park, Chan Hee; Hong, Jae-Keun; Lee, Sang Won; Yeom, Jong-Taek

2017-12-01

Gum metals feature properties such as ultrahigh strength, ultralow elastic modulus, superelasticity, and superplasticity. They are composed of elements from Groups 4 and 5 of the periodic table and exist when the valance electron concentration (\\overline{e/a}) is 4.24; the bond order (\\overline{Bo}) is 2.87; and the "d" electron-orbital energy level (\\overline{Md}) is 2.45 eV. Typical compositions include Ti-23Nb-2Zr-0.7Ta-O and Ti-12Ta-9Nb-6Zr-3 V-O, which contain large amounts of heavy Group-5 elements such as Nb and Ta. In the present study, to improve the specific strength of a multifunctional beta Ti alloy, three alloys (Ti-20Nb-5Zr-1Fe-O, Ti-12Zr-10Mo-4Nb-O, and Ti-24Zr-9Cr-3Mo-O) were designed by satisfying the above three requirements while adding Fe, Mo, and Cr, which are not only lightweight but also have strong hardening effects. Microstructural and mechanical property analyses revealed that Ti-20Nb-5Zr-1Fe-O has a 25% higher specific strength than gum metal while maintaining an ultralow elastic modulus.