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Generation-IV nuclear reactors employ sodium, lead and bismuth(Na, Pb and bismuth) as coolant materials. This technological application requires the knowledge of these metals' properties over a broad temperature span and pressure. Ideal tensile strength is an important characteristic parameter of substances in the metastable state. It can be determined using an appropriate equation of state. Being a characteristic property, the ideal tensile strength is substance-dependent. Hence, Na, Pb and Bi will have different values of the ideal tensile strength. However, the original van der Waals equation of state(vdWEoS), for all substances including Na, Pb and Bi gives the same value of 27 times the critical pressure for the ideal tensile strength. This is physically not reasonable. This points out the need for the generalization the vdWEoS to yield physically reasonable values of the thermodynamic properties of Na, Pb and Bi. To improve its predictive capability, the vdWEoS is generalized into a three-parameter and a four-parameter equations of states with modified attractive terms. The substance-specific parameters of the generalized van der Waals equation of state(gvdWEoS)for Na, Pb and Bi are determined through their vapour-liquid critical-point parameters. The gvdWEoS are employed for determining the ideal tensile strength of Na, Pb and Bi. These values of are found to be-2.6146GPa,-5.7299GPa and-4.3888GPa, respectively. That is, Na, Pb and Bi in the condensed state can withstand, without rupturing, a stretching tension of 2.6146GPa, 5.7299GPa and 4.3888GPa, respectively. [ABSTRACT FROM AUTHOR]

The change in the fine structure of graphite dispersed in a planetary mill for up to 2700 minutes has been studied by the method of X-ray diffraction analysis. The profiles of the asymmetric X-ray diffraction 002 peak of graphite samples were investigated using a code that allows one to isolate overlapping peaks with different gravity centers, intensities, and widths. Separation was carried out into the minimum number of components that adequately describe the experimentally observed asymmetric peak. It is shown that the asymmetric peak consists of a superposition of symmetric peaks of increasing width and corresponding to the values of interlayer distances d002 in the range from 3.37 to 3.55 / 3.68 Å. The observed dependence of the component composition on the duration of dispersion suggests that the process of the transition of graphite into a disordered carbon material, apparently, develops through a number of metastable states. [ABSTRACT FROM AUTHOR]

In the work, the structure, phase composition and mechanical properties of cemented steels were studied, the Fe-Mn-C steels being used as the binder phase. The manganese content in the binder phase varied from 4 to 18 wt %. The carbide phase content in the obtained cemented steels was 82 vol %, the average grain size of WC is 2.4 µm, while the porosity did not exceed 0.5%. It was shown that an increase in the manganese content in the binder phase of cemented steels leads to a change in the phase composition of the binder phase and to an increase in the lattice parameter of austenite. In cemented steels with a content of 4 wt % manganese in the binder phase, which is in a two-phase γ + α state, the maximum axial compression strength (σc = 4050 MPa) is observed. Moreover, in composites, the binder phase of which is in the metastable state of austenite, and the content of martensitic phases, is the maximum residual deformation is minimally observed. It was found that with an increase in the manganese content in the binder phase, a decrease in the compressive strength and permanent deformation to fracture is due to a decrease in the ability of the binder phase to relax stresses and transfer the load to carbide grains. [ABSTRACT FROM AUTHOR]

This manuscript reports spectroscopical effect caused by the incorporation of Tb3+ and Eu3+ ions in Dy3+ doped novel borotellurite glasses with chemical composition of (60–x)B2O3+20TeO2+15Bi2O3+5Al2O3+0.5Dy2O3+0.25X2O3 (where X= Euand Tb) in wt %. In this present case, Dy3+ ions act as sensitizer to both the Tb3+ and Eu3+ ions emissions which originates from the metastable states of Tb3+(5D4) and Eu3+ (5D0)ions through non-radiativeenergy transfer (ηET) with efficiency around 18%. In both the case decreasing emissions intensity of the Dy3+ ions with codopant (Tb3+ and Eu3+) indicates that the interaction between Dy3+ ion and X3+ ions. Luminescence intensity decay profile of 4F9/2 state of the Dy3+ ions estimated and the decreasing lifetime value of Dy3+ ions in codoped glasses confirms the energy transfer from Dy3+ ion to X3+ ions. The nature of interaction is analysed using IH model and the decay profile fitted with S=6 indicates the dipole−dipole type of interaction between sensitizer (Dy3+) and activator (Tb3+ and Eu3+) ions. The characteristic emission color of the prepared glasses were examined through CIE 1931 chromaticity coordinates and the corresponding correlated color temperature (CCT) values were estimated to confirm white light emission. [ABSTRACT FROM AUTHOR]

A molecular dynamics simulation of small PuO2 nanocrystals consisting of 105−174 ions at the temperature T = 1700 K was carried out. The structures of the vertices and the surface created during thermal disordering and subsequent relaxation of these nanocrystals were studied. The vertices formed by two adjacent plutonium cations, as well as truncated vertices of the regular octahedron that consisted of 4 plutonium cations lying in the same plane (100), were most frequently encountered. Sharp vertices of the regular octahedron ending in one cation usually corresponded to metastable states of the crystal lattice or to crystallites with an increased specific energy. According to the results, sequences of the “magic numbers” were proposed to specify the sizes of plutonium dioxide nanocrystals characterized by the most stable surface. [ABSTRACT FROM AUTHOR]

In experiments the free surface temperature during crystallization was Tsc1 = 71 °C and Tsc2 = 88 °C. The height of the aqueous LiBr salt solution decreased from the initial h0 = 3.2 mm to a height of 0.33–0.34 mm corresponding to the onset of crystallization. The displacement of the crystallization front increas significantly at a higher temperature on the free surface Ts of the salt solution. The salt solution passes from the state of unsaturation to the state of supersaturation S with a deeper metastable state. [ABSTRACT FROM AUTHOR]

The ability to identify the preparation process of seismic events using spectral analysis of microseismic noise was earlier shown in laboratory experiment in the form of reduction of natural frequency of oscillations during the transition of the system to a metastable state. Field studies of the Chilean subduction zone allowed us to identify large earthquakes with the same effects before them. In this paper investigation of the natural frequencies of block oscillations, which can be detected in the spectrum of seismic noise, was performed at a lower scale. Measurements were performed near Gubkin (Belgorod region, Russia), where the development of iron ore deposits and explosive works are carried out regularly. We used the data of the high-frequency accelerometer that was installed at the depth of 300 m from the surface. Spectral centroid reduction in the frequency range of 20–1200 Hz was identified before small seismic events with the amplitude of more than 10 mm/s². [ABSTRACT FROM AUTHOR]

In this work the existing SRH parametrizations for the FeGa defect are re-evaluated by a deliberately iron contaminated sample set of varied doping densities. The evolution of the cross-over point is analyzed for this aim, due to its characteristic dependency on the defect parameters of the metastable iron states. It can give insight into the defect parameter, whilst being independent of most factors usually limiting evaluations precision. The proposed parameter adjustment provides an improved description of the measurement data compared to the literature parametrizations. [ABSTRACT FROM AUTHOR]

A sharp fall in the configurational entropy Sc of the liquid is a typical characteristic of the phenomena of liquid-glass transition that occur in the supercooled state. In the present work we report a calculation of S c for a hard sphere fluid by extending the classical density functional theory (DFT) to describe metastable states. In DFT thermodynamic properties of the undercooled liquid is calculated by identifying a metastable state as one for which a suitable free energy reaches a local minimum with respect to an optimum density distribution. The corresponding minimum value of the free energy is calculated by treating inhomogeneous density as an order parameter for the strongly heterogeneous state. In this work, density distribution of the metastable state is described in terms of Gaussian profiles centered on a lattice of random structure which is determined in terms of a pair distribution function g(R((η/η0)1/3) where η0 is a structure dependent parameter. The extrapolated configurational entropy Sc vanishes at η ≈ ηk and ηk is in agreement with other calculations of configurational entropy. The dependence of ηk on the structural parameter η0 is obtained. [ABSTRACT FROM AUTHOR]

The electronic properties of the dication BeRb2+ have been studied using an ab initio approach based on the use of non-empirical pseudopotentials and parameterized l dependent polarization potentials. The potential energy curves and their spectroscopic constants for the ground and the low lying electronic states of 2Σ+ symmetry have been determined. Results show that the 1-22Σ+ and 4-52Σ+ states are repulsive, while the 32Σ+ and 6-92Σ+ are metastable states. Some avoided crossings between the 2Σ+ states have been localized and analysed. Furthermore, the transition dipole moments from the ground state to the higher states of 2Σ+ and 2Π symmetries have been computed. [ABSTRACT FROM AUTHOR]

The electronic properties of the dication BeRb2+ have been studied using an ab initio approach based on the use of non-empirical pseudopotentials and parameterized l dependent polarization potentials. The potential energy curves and their spectroscopic constants for the ground and the low lying electronic states of 2Σ+ symmetry have been determined. Results show that the 1-22Σ+ and 4-52Σ+ states are repulsive, while the 32Σ+ and 6-92Σ+ are metastable states. Some avoided crossings between the 2Σ+ states have been localized and analysed. Furthermore, the transition dipole moments from the ground state to the higher states of 2Σ+ and 2Π symmetries have been computed. [ABSTRACT FROM AUTHOR]

KISS project aims at finding an astrophysical condition for synthesizing r-process heavy element isotopes, which are characterized as the third peak in the solar abundance pattern. This is an experimental challenge in nuclear physics to measure ground and isomeric state properties of unknown nuclei around the region of N=126 isotones. So far we have constructed and developed new type of mass separation system, KISS (KEK Isotope Separation System) and performed measurements of lifetimes and hyperfine structures of some platinum and iridium neutron-rich radioactive isotopes by applying multi-nucleon transfer reactions and in-gas laser ionization and spectroscopy (IGLIS) methods. In this report, recent physics results, updated KISS performance, and future's research plan including a challenge of a systematic mass measurement with MRTOF (Multi-Reflection Time-Of-Flight mass spectrograph) are presented. [ABSTRACT FROM AUTHOR]

Fracture surface analysis is conducted by means of SEM for VT16 titanium alloy specimens solution-treated at temperatures ranging from 700 to 875 °C, water-quenched and subjected to tensile testing. A cup and cone shape failure and dimple microstructure of the fracture surface indicates the ductile behavior of the alloy. Dimple dimensions correlated with the β-grain size of the alloy in quenched condition. The fracture area (namely, the size; the cup and cone shape) depends on the volume fraction of the primary a-phase in the quenched sample. However, the fracture surface changes considerably when the strain-induced β-α"-transformation takes place during tensile testing, resulting in the increase of alloy ductility. [ABSTRACT FROM AUTHOR]

We discuss the physics of the rarest natural isotope 180Ta that has a lifetime of its isomeric state (77 keV) more than 1016 years due to the very large difference of quantum numbers with respect to the ground state. The mechanism of its excitation and subsequent deexcitation at relatively low energies can be explained by the doorway coupling of the isomeric band with the dense spectrum of rotational bands built on the normal deformation. [ABSTRACT FROM AUTHOR]

Presented are the results of laboratory experiments on studying the variation of fault shear stiffness during a seismic cycle. It is shown that the slip mode correlates well with the specific value of fault stiffness ks1 at the loading stage. As the fault goes over to a metastable state, its stiffness changes abruptly from ks1 to 0. This change can be detected in active monitoring, which consists in analyzing the frequency response of an oscillatory "block-fault" system. A periodic pulsed action on the "block-fault" system allowed us to reliably detect a relative decrease by 30% of the resonance frequency of its response when the system goes over to the metastable state. [ABSTRACT FROM AUTHOR]

We use the one-dimensional object-oriented particle-in-cell Monte Carlo collision code oopd1 to explore the spatiotemporal evolution of the electron heating mechanism in a capacitively coupled oxygen discharge in the pressure range 10 - 200 mTorr. The electron heating is most significant in the sheath vicinity during the sheath expansion phase. We explore how including and excluding detachment by the singlet metastable states O2(a¹Δg) and O2(b¹Σ g)+ influences the heating mechanism, the effective electron temperature and electronegativity, in the oxygen discharge. We demonstrate that the detachment processes have a significant influence on the discharge properties, in particular for the higher pressures. At 10 mTorr the time averaged electron heating shows mainly ohmic heating in the plasma bulk (the electronegative core) and at higher pressures there is no ohmic heating in the plasma bulk, that is electron heating in the sheath regions dominates. [ABSTRACT FROM AUTHOR]

Development of Equations of State (EOSs) for the description of highly porous materials exhibiting Hugoniot abnormality is of interest to physicists because of the need to understand shock compression of these materials within a high temperature range. The Mie-Grüneisen EOS is usually a basis of such new EOSs. The present work also follows the Mie-Grüneisen approximation, which is complemented with a two-phase consideration for the porous material analysed, while employing simple EOSs for each of the two phases. The Hugoniot abnormality has previously been analysed with a two-phase material model implemented in the CTH hydrocode. The analysis has shown that the inter-phase pressure and temperature equilibrium that is achieved under moderate shock waves, is the necessary condition for manifestation of the abnormality in highly porous materials, whereas under stronger waves the equilibrium achieved only by pressure connects metastable states in the high-pressure section of a Hugoniot manifesting normal behaviour. The present Hugoniot in analytical form consists of the two sections distinguished by equilibrium conditions and correlates well with the experimental data available in the literature. [ABSTRACT FROM AUTHOR]

Atomistic mechanisms underlying the reaction time and intermediate reaction products of detonating high explosives far from equilibrium have been elusive. This is because detonation is one of the hardest multiscale physics problems, in which diverse length and time scales play important roles. Here, large spatiotemporal-scale reactive molecular dynamics simulations validated by quantum molecular dynamics simulations reveal a two-stage reaction mechanism during the detonation of cyclotrimethylenetrinitramine cystal. Rapid production of N2 and H2O within ~10 ps is followed by delayed production of CO molecules beyond ns. We found that further decomposition towards the final products is inhibited by the formation of large metastable carbon- and oxygen-rich clusters with fractal geometry. In addition, we found distinct unimolecular and intermolecular reaction pathways, respectively, for the rapid N2 and H2O productions. [ABSTRACT FROM AUTHOR]

Absorption spectroscopy technique was used to measure the densities of sputtered atoms in the ground state and metastable state in pulse-modulated sputtering plasmas with compound Cu2ZnSnS4(CZTS) target. At a fixed discharge power, the absolute metastable densities of sputtered Cu, Zn, and Sn atoms increased with the argon pressure. This characteristic is believed due to the enhancement of plasma density with increasing argon pressure, which would increase the excitation rate of sputtered atoms. In addition, the metastable state densities of sputtered atoms are equal or higher than that of the ground state densities. Therefore, these experimental results reveal that the contribution of metastable atoms should be taken into account during the calculation and simulation of thin film growth via sputtering plasmas. [ABSTRACT FROM AUTHOR]

Absorption spectroscopy technique was used to measure the densities of sputtered atoms in the ground state and metastable state in pulse-modulated sputtering plasmas with compound Cu2ZnSnS4(CZTS) target. At a fixed discharge power, the absolute metastable densities of sputtered Cu, Zn, and Sn atoms increased with the argon pressure. This characteristic is believed due to the enhancement of plasma density with increasing argon pressure, which would increase the excitation rate of sputtered atoms. In addition, the metastable state densities of sputtered atoms are equal or higher than that of the ground state densities. Therefore, these experimental results reveal that the contribution of metastable atoms should be taken into account during the calculation and simulation of thin film growth via sputtering plasmas. [ABSTRACT FROM AUTHOR]

The process parameters of the frictional treatment (indenter material, medium, load) of the 12Kh18N10T chromium-nickel austenitic steel have been optimized for the criteria of strain hardening and the quality of the surface being treated. The paper studies effect of the multiplicity of the frictional action of a synthetic diamond indenter at room temperature in an argon medium and the loading temperature ranging between -196 °C and +250 °C on the hardening, phase composition and fine structure of the surface layer of the steel. It has been found that the completeness of the strain-induced γ→α' martensitic transformation in the surface layer of the steel is strongly dependent on the multiplicity and temperature of loading and that the level of hardening rises with the multiplicity of action, but shows little dependence on the temperature of frictional treatment. [ABSTRACT FROM AUTHOR]

The features of the structural-phase states and mechanical properties of metastable austenitic steel after thermomechanical treatments have been investigated. It is shown that low-temperature and subsequent deformation in the temperature range 300-773 K contributes to the direct (γ → α')-martensitic transformation. The combination of lowtemperature, subsequent warm deformation at 873 K and annealing at 1073 K leads to the direct (γ → α')- and reverse (α' → γ)-martensitic transformations. As a result of thermomechanical treatments submicrocrystalline two-phase structural states with high strength properties (σ0.1 ≈ 1160-1350 MPa) are formed. [ABSTRACT FROM AUTHOR]

An overview is presented of the progress in baryon spectroscopy from Jefferson Lab, and in particular from the CLAS experimental program. A range of photoproduction measurements have been carried out, which include the extraction of several polarization observables for different reaction channels. The results so far show that these data can be very useful in the search for evidence for new resonant states. A large amount of data is yet to be published from the program. [ABSTRACT FROM AUTHOR]

In the present paper, we study propagation of a soliton at an interface formed between special type of chalcogenide fibre and gallium in three different phases with the help of equivalent particle theory. Critical angle of incidence and critical power required for transmission and reflection of soliton beam have investigated. Here it is found that if the incident angle of the beam or initial velocity of the equivalent particle is insufficient to overcome the maximum increase in potential energy then the particle (light beam) is reflected by the interface and if this incident angle is greater than a critical angle then light beam will be transmitted by the interface. From an equation these critical angles for α-gallium, one of a metastable phase and liquid gallium are calculated and concluded that at large incident angles, the soliton is transmitted through the boundary, whereas at small incidence angles the soliton get reflected on keeping the power of incident beam constant. These results are explained by phase plane trajectories of the effective potential which are experimentally as well as theoretically proved. [ABSTRACT FROM AUTHOR]

The oxidation behavior of Ni-Fe-41.5Al alloy with different Fe/Ni ratio was investigated in air at 1000°C using in-situ high-temperature X-ray diffraction study by means of Synchrotron radiation. The oxidation mass gain of alloys decreased with increasing Fe content, particularly initial oxidation mass gain significantly decreased with increasing alloy Fe content. In-situ X-ray diffraction study indicated that the stable α-Al2O3 formed from beginning of oxidation on the alloy with higher Fe ratio, but metastable Al2O3 formed on the alloy with lower Fe ratio, and it remained longer when alloy Fe ratio was decreased. The effect of Fe on promoting a-Al2O3 formation is explained due to initial formation of α-Fe2O3, which has isomorphous structure with α-Al2O3. The additional effect of Fe on the growth rate of α- Al2O3 was also discussed. [ABSTRACT FROM AUTHOR]

This paper presents experimental investigation of the two-phase refrigerant flow through helical adiabatic capillary tube and non-adiabatic (diabatic) capillary tubes-suction tube heat exchanger. The experimental results indicate that mass flux ratio is main parameter that affects metastable flow through both type of adiabatic and non-adiabatic capillary tubes. Therefore, an increase of the mass flux ratio represents a decrease of the heat transfer rate between the capillary tube and suction line. The measured and saturated pressure distribution also proof that metastable flow in the non-adiabatic coiled capillary tube with 1.397 mm inner diameter, 30 mm coil diameter, 4360 mm length, exists when the rate of heat transfer between the coiled capillary tube and the suction line is weak with mass flux ratio Gc/Gs> 343. [ABSTRACT FROM AUTHOR]

Investigations of the fragmentation potential energy surface is realized in the frame of the macroscopicmicroscopic model in order to emphasize the importance of the shell effects in the synthesis and the stability of superheavy nuclei. The origin of several minima that are responsible for metastable states is discussed. [ABSTRACT FROM AUTHOR]

The time differential perturbed angular distribution (TDPAD) technique has been used to measure the quadrupole moments of the 7- and 23/2+ states in 128,129Ba w.r.t. 9/2- state in 129Ba following the 120Sn(12C, xn)128'129Ba on Tb metal foils. The observed values are at variance with the intraband nalysis. [ABSTRACT FROM AUTHOR]

Granular solid hydrodynamics (GSH) is employed to account for granular rheology, both the rate-controlled one, smoothly extending from the critical state to the Bagnold regime, and the stress-controlled one that is discontinuous and hysteretic. Employing GSH, it is shown that a quiescent state is stable below the smaller jamming stress and instable above the larger fluidization stress, with values in between being metastable; also, that the MiDi relation, appropriate for rigid grains, needs to be rectified, because real granular media, with a sound velocity one to three times that of air, are soft. [ABSTRACT FROM AUTHOR]

We reveal that the transition in the saturated flux for aeolian saltation is generically discontinuous by explicitly simulating particle motion in turbulent flow in two dimensions. The discontinuity is followed by a coexistence interval with two metastable solutions. We found also that the mere presence of mid-air collisions, surprisingly, enhances the saturated flux, which has a peak for an intermediate restitution coefficient of 0.65. [ABSTRACT FROM AUTHOR]

Shock waves in nickel were simulated by molecular dynamics using a new EAM potential. Three distinct regimes of shock propagation were observed, including a single elastic shock wave, two split elastic and plastic shock waves, and a single two-zone elastic-plastic shock wave, in order of increasing piston velocity. The single two-zone wave consists of a leading lower-pressure elastic zone, followed by a higher-pressure plastic wave, both moving with the same average speed. The elastic zone of this wave is compressed to a metastable state having an average pressure above the Hugoniot elastic limit. Similar metastable states appear in the elastic precursor during the early stage of split wave development. The mechanism for relaxation of the metastable elastic state is discussed. [ABSTRACT FROM AUTHOR]

Synchrotron based angle dispersive x-ray diffraction (ADXRD) studies were performed on metastable crystalline bismuth orthoborate (BiBO3) up to 14.5 GPa during compression and decompression cycle. These studies revealed that the BiBO3 is unstable and it converts to Bi4B2O9 phase at high pressure. Moreover the transformation is found to be irreversible. [ABSTRACT FROM AUTHOR]

Synchrotron based angle dispersive x-ray diffraction (ADXRD) studies were performed on metastable crystalline bismuth orthoborate (BiBO3) up to 14.5 GPa during compression and decompression cycle. These studies revealed that the BiBO3 is unstable and it converts to Bi4B2O9 phase at high pressure. Moreover the transformation is found to be irreversible. [ABSTRACT FROM AUTHOR]

We present a method of interpolation of thermodynamic functions calculated by means of a multiphase equation of state for metals. The method takes into account melting, evaporation and sublimation phase transitions. It can be also applied in metastable regions of phase diagram including those under negative pressures. The method allows one to unambiguously determine the phase state of a given point of phase diagram. Several applications of the tabular multiphase equations of state are considered: simulation of the initial stage of electrical explosion of metal wires, formation of striations, interaction of intense laser pulses with matter etc. Information about phase state in every point of the flux allows us to study phase transition waves, apply different destruction criteria and analyze processes in metastable regions. [ABSTRACT FROM AUTHOR]

We describe our recent work using atomic ensembles to store quantum states of light and control light propagation and its quantum properties. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

The α→β transformation characteristics in U-15wt.% Cr alloy have been investigated by dilatometry at slow heating rates (3-10 K min-1). The starting microstructure of U-15Cr alloy consists of a mixture of metastable βm-U(body centred tetroganal), α-U(orthorhombic) and elemental Cr(bcc) phases. Upon heating, the metastable βmU phase has progressively transformed to equilibrium α-U structure; before, finally undergoing equilibrium α→β transformation with further increase in temperature. The measured α→β transformation temperature, when extrapolated to 0 K min-1 heating rate has been found to be higher than the currently accepted equilibrium phase diagram estimate. This is due to the kinetic difficulty associated with Cr-diffusion in U-15Cr alloy. The kinetics of α→β transformation upon continuous heating has been modeled in terms of a suitable framework for diffusional transformations, and the effective activation energy for overall transformation has been estimated to be in the range 160-180 kJ mol-1. [ABSTRACT FROM AUTHOR]