High Energy Region Research Articles

Bis-(Fluorene)-Embedded Hexaphyrins.

The polyaromatic hydrocarbon containing expanded porphyrins, bis-(fluorene)-embedded hexaphyrins, were synthesized by condensing fluorene-based tripyrrane with pentafluorobenzaldehyde in CH2Cl2 in the presence of 1 equiv of BF3·OEt2 under an inert atmosphere followed by oxidation with DDQ in open air at room temperature. The reaction worked only when 1 equiv of BF3·OEt2 was added to the reaction mixture under concentrated reaction conditions. The bis-(fluorene)-embedded macrocycles were characterized and studied by high-resolution mass spectrometry (HRMS), nuclear magnetic resonance (NMR), absorption, electrochemical, and density functional theory (DFT)/time-dependent (TD)-DFT techniques. In 1H NMR, the hexaphyrins showed a few broad unresolved resonances at room temperature, but the NMR spectra were well-resolved at lower temperatures, indicating that the hexaphyrins were very flexible. The DFT-optimized structures indicated that the two fluorene units at the crossing point of the figure-eight loop makes an angle of ∼79.73° with each other, the fluorene moieties maintained their own planarity, and one of the fluorene moieties was not involved in conjugation with the rest of the macrocycle. The absorption spectra of hexaphyrins showed one intense sharp band in the higher energy region and a broad band in the lower energy region. The electrochemical studies indicated that expanded hexaphyrins are relatively electron-rich and showed three easier oxidations and one reduction. The DFT/TD-DFT studies are in agreement with the experimental observations.

Cross-track error estimation of wide-swath altimeters based on reference topography data

ABSTRACT Wide-swath altimeters, which can provide unprecedented fine-scale data for marine research, are an important development direction in the new generation of satellite altimeters. However, the cross-track error, one of the main error sources for wide-swath altimeters, must be fully estimated and corrected. Error estimation based on reference topography data (RTD) is effective. Since the sea surface is dynamic, the time difference between the RTD and the measured topography will cause the cross-track error to be misidentified. Limited by the temporal or spatial resolution, averaging the gridded RTD can improve its overall performance but will weaken the instantaneous characteristics. Therefore, it is necessary to select RTD with an effective time interval according to the changes in the surface topography within the target area. This paper uses gridded mean sea surface data and daily sea level anomaly data to construct input data sets and generate output data with errors in different experimental areas through the SWOT Simulator. Two RTD methods with different time spans are used to estimate and correct the cross-track error, and the effective time is calculated by the root mean square error of the residual part. The results show that the effective time is approximately 3 days in high-energy regions but can be extended to more than 10 days in low-energy regions.

"Spine Surgery" of Perylene Diimides with Covalent B-N Bonds toward Electron-Deficient BN-Embedded Polycyclic Aromatic Hydrocarbons.

BN-embedded polycyclic aromatic hydrocarbons (PAHs) with unique optoelectronic properties are underdeveloped relative to their carbonaceous counterparts due to the lack of suitable and facile synthetic methods. Moreover, the dearth of electron-deficient BN-embedded PAHs further hinders their application in organic electronics. Here we present the first facile synthesis of novel perylene diimide derivatives (B2N2-PDIs) featuring n-type B-N covalent bonds. The structures of these compounds are fully confirmed through the detailed characterizations with NMR, MS, and X-ray crystallography. Further investigation shows that the introduction of BN units significantly modifies the photophysical and electronic properties of these B2N2-PDIs and is further understood with the aid of theoretical calculations. Compared with the parent perylene diimides (PDIs), B2N2-PDIs exhibit deeper highest occupied molecular orbital energy levels, new absorption peaks in the high-energy region, hypsochromic shift of absorption and emission maxima, and decrement of photoluminescent quantum yields. Single-crystal field-effect transistors based on B2N2-PDIs showcase an electron mobility up to 0.35 cm2 V-1 s-1, demonstrating their potential application in optoelectronic materials.

Fourier transform infrared and Raman spectra of the complex cation diethyldithiocarbamate Cr(III) Di-hydrate, [Cr(DDTC)2(OH2)2]+. UV-Vis spectrum, DFT:B3LYP/6-311G(d, p) structural determination, vibrational and natural bond orbital analysis

Diethyldithiocarbamate Cr(III) di-hydrate, [Cr(DDTC)2(OH2)2]+ was synthesized and the analysis of its structure was performed. The calculations as well as its infrared and Raman spectra interpretation were based on the DFT/B3LYP method. The vibrational spectra show a blue shift of the bands in the high energy region (C-H stretching of the -CH3 and -CH2 groups), a result corroborated by the calculated spectra. Besides, the blue shift of the C-H bands of the CH3 and CH2 groups of the complex was interpreted by means of the intermediate hybridization between the sp3 and sp2 orbitals of the carbon atoms whose bonds increased the force constants, shifting the position of the CH bands to the blue. The geometry of the complex produced wave numbers with excellent agreement with the experimental ones, thus indicating that the proposed geometry is correct. Electronic transitions spin allowed (ν1, ν2 and ν3) according to the time-dependent process using the B3LYP functional with basis 6-311G(d,p), and according to the TS diagram they were assigned as: ν12T1g(G)←4A2g (Bu), ν24T2g(F)←4A2g(Ag). ν34T1g(F)←4A2g(Ag). The agreement between the two procedures that led to the assignment was excellent. Natural bond orbital analysis was also carried out as a way to find the hybridization of the carbon atoms of the –CH3 and –CH2 groups. Koopmans’ energy (eV), Mulliken population analysis and assignment for the frontier orbitals of [Cr(DDTC)2 (OH2)2]+, with the B3LYP method, were also performed.

Bromine K-Edge X-Ray Absorption Near-Edge Structure Analysis on Hydrobromide-Salt Crystals and the Solid Dispersion of Active Pharmaceutical Ingredients.

Bromine K-edge X-ray absorption near-edge structure (XANES) spectroscopy analyses were used to evaluate the crystals of the active pharmaceutical ingredients, eletriptan hydrobromide, dextromethorphan hydrobromide and scopolamine hydrobromide salts and the solid dispersion of eletriptan hydrobromide. The crystals and the solid dispersion of the active pharmaceutical ingredient (API) salts could be discriminated based on the shape of the XANES spectra. The differences in the shape of XANES spectra was ascribable to the differences in the interatomic interactions of the bromine ions based on the crystal structures. Ratio of the eletriptan hydrobromide α-form crystal in mixed powders of α-form and monohydrate crystals could be quantified by the linear-combination fitting using their XANES spectra. These results indicated that the XANES spectroscopy are a potent method for evaluating the APIs of pharmaceutical formulations even at the higher energy region around the bromine K-edge of 13470 eV.

Search for sterile neutrinos by shower events at a future neutrino telescope

Abstract It is pointed out that searching for sterile neutrinos in high energy regions at a future IceCube-like facility has advantages compared with reactor or short baseline accelerator neutrino experiments, in which the size of the detector and energy resolution make it difficult to gain good sensitivity for a large mass-squared difference. In this study we show that it is possible to improve constraints on sterile neutrino mixing θ14 for 1 eV$^2 \lesssim \Delta m_{41}^2\lesssim$ 100 eV2 by looking for a dip in the shower events at an IceCube-like neutrino telescope whose volume is at least 10 times as large as that of IceCube and whose duration is 10 years. We also give an analytic expression for the oscillation probabilities in two cases where the condition of one mass scale dominance is satisfied.

Assessment of secondary neutrons in particle therapy by Monte Carlo simulations

Objective. The purpose of this study is to estimate the energy and angular distribution of secondary neutrons inside a phantom in hadron therapy, which will support decisions on detector choice and experimental setup design for in-phantom secondary neutron measurements. Approach. Dedicated Monte Carlo simulations were implemented, considering clinically relevant energies of protons, helium and carbon ions. Since scored quantities can vary from different radiation transport models, the codes FLUKA, TOPAS and MCNP were used. The geometry of an active scanning beam delivery system for heavy ion treatment was implemented, and simulations of pristine and spread-out Bragg peaks were carried out. Previous studies, focused on specific ion types or single energies, are qualitatively in agreement with the obtained results. Main results. The secondary neutrons energy distributions present a continuous spectrum with two peaks, one centred on the thermal/epithermal region, and one on the high-energy region, with the most probable energy ranging from 19 up to 240 MeV, depending on the ion type and its initial energy. The simulations show that the secondary neutron energies may exceed 400 MeV and, therefore, suitable neutron detectors for this energy range shall be needed. Additionally, the angular distribution of the low energy neutrons is quite isotropic, whereas the fast/relativistic neutrons are mainly scattered in the down-stream direction. Significance. It would be possible to minimize the influence of the heavy ions when measuring the neutron-generated recoil protons by selecting appropriate measurement positions within the phantom. Although there are discrepancies among the three Monte Carlo codes, the results agree qualitatively and in order of magnitude, being sufficient to support further investigations with the ultimate goal of mapping the secondary neutron doses both in- and out-of-field in hadrontherapy. The obtained secondary neutron spectra are available as supplementary material.

Crystallization induced room-temperature phosphorescence and chiral photoluminescence properties of phosphoramides.

We report the design and synthesis of a series of room temperature phosphorescent phosphoramides TPTZPO, TPTZPS, and TPTZPSe with a donor (phenothiazine)–acceptor (P = X, X = O, S, and Se) architecture. All the compounds show structureless fluorescence with a nanosecond lifetime in dilute solutions. However, these compounds show dual fluorescence and room temperature phosphorescence (RTP) in the solid state. Both the intensity and energy of luminescence depend on the heteroatom attached to the phosphorus center. For example, compound TPTZPO with the P Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> O unit exhibits fluorescence at a higher energy region than TPTZPS and TPTZPSe with the PS and PSe groups, respectively. Crystalline samples of TPTZPO, TPTZPS, and TPTZPSe show stronger RTP than the amorphous powder of respective compounds. Detailed steady-state, time-resolved photoluminescence and computational studies established that the 3n–π* state dominated by the phenothiazine moiety is the emissive state of these compounds. Although TPTZPS and TPTZPSe crystallized in the chiral space group, only TPTZPSe showed chiroptical properties in the solid state. The luminescence dissymmetry factor (glum) value of TPTZPS is small and below the detection limit, and a CPL spectrum could not be observed for this compound.

Effects of local exchange field in different directions on spin transport of stanene

Topological insulator is a new quantum state of matter in which spin-orbit coupling gives rise to topologically protected gapless edge or surface states. The nondissipation transport properties of the edge or surface state make the topological device a promising candidate for ultra-low-power consumption electronics. Stanene is a type of two-dimensional topological insulator consisting of Sn atoms arranged similarly to graphene and silicene in a hexagonal structure. In this paper, the effects of various combinations of local exchange fields on the spin transport of stanene nanoribbons are studied theoretically by using the non-equilibrium Green's function method. The results show that the spin-dependent conductance, edge states, and bulk bands of stanene are significantly dependent on the direction and strength of the exchange field in different regions. Under the joint action of the exchange fields in [I: <inline-formula><tex-math id="M12">\begin{document}$ \pm Y $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M12.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M12.png"/></alternatives></inline-formula>, II: <inline-formula><tex-math id="M13">\begin{document}$ +Z $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M13.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M13.png"/></alternatives></inline-formula>, III: <inline-formula><tex-math id="M14">\begin{document}$ \pm Y $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M14.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M14.png"/></alternatives></inline-formula>] direction, the edge states form a band-gap under the influence of the <i>Y</i>-direction exchange field. The band-gap width is directly proportional to the exchange field strength <i>M</i>, and the conductance is zero in an energy range of <inline-formula><tex-math id="M15">\begin{document}$ -M<E<M $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M15.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M15.png"/></alternatives></inline-formula>. When the exchange fields in the direction of <inline-formula><tex-math id="M16">\begin{document}$ +Z $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M16.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M16.png"/></alternatives></inline-formula> or <inline-formula><tex-math id="M17">\begin{document}$ -Z $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M17.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M17.png"/></alternatives></inline-formula> are applied, respectively, to the upper edge region and the lower edge region at the same time, the spin-up energy band and the spin-down energy band move to a high energy region in opposite directions, and strong spin splitting occurs in the edge state and bulk bands. Increasing the strength of the exchange field, the range of spin polarization of conductance spreads from the high energy region to the low energy region. When the directions of the exchange field are [I: <inline-formula><tex-math id="M18">\begin{document}$ \mp Z $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M18.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M18.png"/></alternatives></inline-formula>, II: <inline-formula><tex-math id="M19">\begin{document}$ \pm Y $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M19.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M19.png"/></alternatives></inline-formula>, III: <inline-formula><tex-math id="M20">\begin{document}$ \pm Z $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M20.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M20.png"/></alternatives></inline-formula>], the edge states are spin degenerate, but the weak spin splitting occurs in the bulk bands. Under the condition of different exchange field strengths, the spin-dependent conductance maintains a conductance platform of <inline-formula><tex-math id="M21">\begin{document}$ G_\sigma=e^2/h $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M21.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M21.png"/></alternatives></inline-formula> in the same energy range of <inline-formula><tex-math id="M22">\begin{document}$ -\lambda_{\rm so} <E<\lambda_{\rm so} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M22.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20220277_M22.png"/></alternatives></inline-formula>.

Electronic spectroscopy of cationic adamantane clusters and dehydrogenated adamantane in helium droplets.

We report the first helium-tagged electronic spectra of cationic adamantane clusters, along with its singly, doubly, and triply dehydrogenated analogues embedded in helium droplets. Absorption spectra were measured by recording the evaporation of helium atoms as a function of laser wavelength in the range of 300-2150 nm. Experimental spectra are coupled with simulated spectra obtained from quantum chemical calculations. The spectrum of cationic adamantane agrees with the electronic photodissociation spectrum measured previously, with an additional low-energy absorption at around 1000 nm. The spectra of the dehydrogenated molecules present broad absorptions exclusively in the high-energy region (300-600 nm). For the higher order adamantane dimer and trimer ions, strong absorptions are observed in the low-energy region (900-2150 nm), rationalised by transitions delocalised over two adamantane units.

Correlation and decomposition concepts for identifying and disentangling flow structures: Framework and insights into turbulence organization

Turbulence and its organization, long conceptualized in terms of “coherent structures,” has resisted clear description. A significant limitation has been the lack of tools to identify instantaneous, spatially finite structures, while unraveling their superposition. We present a framework of generalized correlations, which can be used to readily define a variety of correlation measures, aimed at identifying field patterns. Coupled with Helmholtz-decomposition, this provides a paradigm to identify and disentangle structures. We demonstrate the correlations using vortex-based canonical flows and then apply them to incompressible, homogeneous, isotropic turbulence. We find that high turbulence kinetic energy (Ek) regions form compact velocity-jets that are spatially exclusive from high enstrophy (ω2) regions that form vorticity-jets surrounded by swirling velocity. The correlation fields reveal that the energetic structures in turbulence, being invariably jets, are distinct from those in vortex-based canonical flows, where they can be jet-like as well as swirling. A full Biot–Savart decomposition of the velocity field shows that the velocity-jets are neither self-induced, nor induced by the interaction of swirling, strong vorticity regions, and are almost entirely induced, non-locally, by the permeating intermediate range (rms level) vorticity. Velocity-swirls, instead, are a superposition of self-induced and background-induced velocity. Interestingly, it is the mild intermediate vorticity that dominantly induces the velocity-field everywhere. This suggests that turbulence organization could result from non-local and non-linear field interactions, leading to an emergent description unlike the notion of a strict structural hierarchy. Our correlation-decomposition framework lends itself readily to the study of generic vector and scalar fields associated with diverse phenomena.

W L-shell X-ray emission induced by C<sup>6+</sup>ions in the energy range of several hundred MeV/u

The L-shell X-ray emissions of tungsten has been investigated under the bombardment of C<sup>6+</sup> ions in the high energy region of 154 - 424 MeV/u. Compared to the atomic data, the energy of the X-ray is enlarged, and the relative intensity ratios of Lı, Lβ<sub>1, 3, 4</sub> and Lβ<sub>2, 15</sub> to Lα<sub>1, 2</sub> X-rays are enhanced. The L-subshell and the total X-ray production cross sections were calculated by a well corrected thick target formula and compared with the theoretical estimation of BEA, PWBA and ECPSSR. On the whole, the experimental cross sections are all smaller than the prediction of PWBA and ECPSSR, but in agreement roughly with that of BEA. It is indicated that the inner-shell ionization of W can be considered to be a binary process between the high energy C<sup>6+</sup> ions acting as a point charge and the independent target electrons. With the L-shell ionization, the outer-shells are multiply ionized. The multi-ionization degree is regard to be almost constant in the present work. This results in the X-ray energy blue shift and the enhancement of the relative intensity ratios of Lı and Lβ to Lα X-ray. Using the atomic parameters corrected by multi-ionization, the X-ray production cross section can be estimated by the BEA model.

Study of Alpha Particle Impact Double Ionization Cross Sections of Cu Atom

Semi-classical binary encounter approximation has been used for the study of ionization cross sections of Cu atom at ground state. Projectile, alpha particle, with energy varying from threshold to 360 keV/amu are considered for direct double ionizations cross section. Out of the two path ways of ionization we have ruled out the indirect process (like excitation-auto ionization, Auger effect) of double ionization. We considered direct - ionization of outer shells of Cu atom. Vriens accurate expression of cross section for energy transfer ΔE(σΔE ) and Hertree-Fock velosity distribution function for the target electrons are used. The theoretical value of double ionization cross sections at impact energy 300 keV/amu is 0.98 x 10-16 cm2 which is same as experimental values at that impact energy. Above energy of 300 keV/amu, the calculated results underestimates the experimental data and at 360 keV/amu their magnitude are 0.77 x 10-16 and 1.0 x 10-16 respectively. Above impact energy of 75keV/amu, all the theoretical results have ratio factor within 2. Out of the total number of theoretical data 75% are under valid range of ratio factor 2 and among the valid range 41% have ratio factor below 1.325 and hence calculated results of double ionization cross section lie in the acceptable range. The linear correlation coefficient (R square) and standard deviation (SD) of linear fit are 0.6984 and 0.7883 respectively. In low energy range the theoretical results are more apart from corresponding experimental values and possess relatively more error compared to intermediate and higher energy region. Calculated results are in satisfactory agreement with experiment in intermediate and high energy range.

EFFECT OF THE COULOMB INTERACTION TO THE PROCESSES OF INELASTIC DEUTERON SCATTERING ON NUCLEI AND THE STRUCTURE OF DEUTERON

The available experimental data on the interaction of polarized and unpolarized deuterons with a large deuteron momentum transfer require their theoretical description and interpretation. At the same time, further experimental studies require theoretical predictions in turn. In particular, there is a need to develop a theoretical model that makes it possible to smoothly connect available experimental data obtained at low-energy region, at which the nucleon-meson structure of the deuteron appears, with data obtained at high-energy region. The latter are related to the structure of the deuteron at small distances. Approaches based on the quark description of the deuteron structure are more adequate for their interpretation. The creation of such a model is an urgent task of modern nuclear physics, since it will allow one to reliably compare the asymptotic predictions of perturbative quantum chromodynamics and other quark approaches with the available experimental data. This will also make it possible to develop the theoretical approaches necessary for planning future experimental studies of elastic and inelastic deuteron scattering at high energies. In the framework of the Glauber–Sitenko model, the contribution of the Coulomb interaction to the reaction cross section A(d,p) at high energies and zero proton angle is calculated. The effect of taking into account the Coulomb interaction for the cross section in a wide inter-nuclear region is evaluated. The present calculations are compared with experiment. One fines that the Coulomb interaction gives a sizable contribution in the observables only at a peak, where the proton momentum is near half of the deuteron momentum in the lab. frame. But it does not change the results in the high momentum region, where quark effects should be taken into account.

Evidence of auger heating in hot carrier cooling of CsPbBr3 nanocrystals

Hot Carrier (HC) Dynamics in Lead halide perovskites shows a unique hindered hot carrier cooling. In the present study, we use femtosecond transient absorption technique to interrogate CsPbBr3 to study the role of different carrier cooling mechanisms in HC cooling process. This is accomplished here by considering fitting of the high-energy region of photoinduced bleach with a Fermi-Dirac distribution instead of Maxwell-Boltzmann Distribution. This approach reveals important time dependent parameters like quasi fermi level, apart from carrier temperature. Under low carrier densities with N < <1, the dynamics revealed bleach recovery in time scales > 1 ns revealing dynamics is governed by electron-hole radiative recombination. The HC cooling dynamics under low carrier density (2 *1017/cm3) revealed the cooling is predominantly dominated by short lifetime component of ~0.26 ps. This time is significantly elongated as compared to lifetime of longitudinal optic (LO) phonon lifetime in perovskites, clearly indicative of Froehlich interaction in play along with large polaron formation. However, under higher carrier densities > 1018/cm3, additional lifetime component contributes to HC cooling with a time constant of ~17 ps. This time constant could be assigned to Auger heating. The role of LO phonon filling and Auger heating was ascertained also on the basis energy loss rate vs carrier temperature fitting with these individual cooling models. To ascertain the role of Auger heating we also used different sized samples which showed the scaling of Auger heating times in agreement with size dependent Auger recombination times as reported in the literature. Such long HC cooling opens avenues to possibly extract hot carriers before cooling leading to development of HC photovoltaics.

Different mechanisms for the seasonal variations of the mesoscale eddy energy in the South China Sea

Using a recently developed functional analysis tool, Multiscale Window Transform (MWT) and the MWT-based theory of canonical transfer, this study investigates the dynamical processes responsible for the seasonal variability of the mesoscale eddies in the South China Sea (SCS). A three-scale energetics framework is employed, in which the original fields are decomposed into subfields on a nonstationary background flow window, a mesoscale eddy window and a high-frequency synoptic eddy window. Three local regions of high mesoscale eddy kinetic energy (EKE) levels, namely, the southwest of Taiwan Island (SWT), the southeast of Vietnam (SEV) and the northeast of the Natuna Island (NEN), are identified. The seasonal cycles of the mesoscale EKE in the three regions are not in phase, with peaks occurring around January, October and December, respectively. By diagnosing the canonical transfers between the background flow and the mesoscale eddies, we find that the seasonal cycle of the eddy variability in the SWT region is due to a mixed instability (baroclinic and barotropic instabilities), while barotropic instability plays a dominant role in determining the EKE seasonality in the SEV and NEN regions. This is quite different from the previous argument that baroclinic instability dominates the seasonal EKE in the SCS. The three-scale framework further reveals that high-frequency synoptic motions act to dissipate the lower-frequency mesoscale eddies through forward energy cascades. Besides the internal processes, external wind forcing is also found to influence the seasonal eddy variability, but is only limited to the NEN region. Our results highlight different mechanisms controlling the seasonal modulations of the mesoscale eddies in different regions of the SCS.

Theoretical Insights into Electronic Nematic Order, Bond-Charge Orders, and Plasmons in Cuprate Superconductors

In this article, we focus on the charge degree of freedom in cuprate superconductors and review theoretical insights into the electronic nematic order, bond-charge orders, and plasmons. The low-energy charge dynamics is controlled by the spin-spin interaction J, which generates various bond-charge ordering tendencies including the electronic nematic order. The nematic order is driven by a d-wave Pomeranchuk instability and is pronounced in the underdoped region as well as around van Hove filling in the hole-doped case; the nematic tendency is weak in the electron-doped region. Nematicity consistent with the d-wave Pomeranchuk instability was reported for hole-doped cuprates in various experiments. Although the t-J and Hubbard models correctly predicted the proximity to the nematic instability in cuprates far before the experimental indications were obtained, full understanding of the charge ordering tendencies in hole-doped cuprates still requires further theoretical studies. In electron-doped cuprates, on the other hand, the d-wave bond-charge excitations around momentum q=(0.5pi,0) explain the resonant x-ray scattering data very well. Plasmon excitations are also present and the agreement between the large-N theory of the t-J model and resonant inelastic x-ray scattering measurements is nearly quantitative in both hole- and electron-doped cuprates. Theoretically the charge dynamics in cuprates is summarized as a dual structure in energy space: the low-energy region scaled by J, where the nematic and various bond-charge orders are relevant, and the high-energy region typically larger than J, where plasmons are predominant.

Pressure induced structural, electronic and optical properties of wurtzite beryllium monoxide (w-BeO) from first-principle calculations

All-electron density functional calculations of structural, electronic and optical properties of wutrzite beryllium oxide (w-BeO) are carried out at different applied hydrostatic pressure. Calculated lattice constants decrease (a, c), while bulk modulus increases with increasing pressure. Direct fundamental band-gap (Eg) of w-BeO increases with increasing pressure and vice versa and the variation provides first and second order pressure coefficient of band-gap. The calculated volume deformation potential of band-gap of w-BeO is −11.5972 eV. Optical properties of w-BeO at zero and high pressures have been studied in terms of dielectric function ε(ω) and related ancillary optical parameters. Each optical parameter is marginally anisotropic. Calculated components of refractive index at each pressure signify uniaxial characteristics of the w-BeO. Calculated components of static dielectric constant, refractive index and reflectivity decreases, while critical point energy in the spectra of each component of ε2(ω), k(ω), σ(ω) and α(ω) increases with increasing pressure and vice versa. Calculated optical energy-gap (Eopt) of w-BeO increases like Eg with increasing pressure and vice versa. The transmission cutoff energy (ECutoff) is shifted towards the higher energy region with increasing pressure.

Stopping power and CSDA range calculations of electrons and positrons over the 20 eV–1 GeV energy range in some water equivalent polymer gel dosimeters

In this study, the stopping power, CSDA range and radiation yield calculations of electrons and positrons over the 20 eV–1 GeV energy range in some water equivalent polymer gel dosimeters were performed. For collision stopping power calculations of electrons and positrons the effective charge concept proposed by Sugiyama were considered. Here, both the effective charge of incident electrons and positrons (z*) and the effective charge (Z*) and the effective mean excitation energy (I*) of the target material were calculated. For the density effect correction the Fano model was selected. For the radiative stopping power analytical model based on the ratio between the collision and the radiative stopping power discribed by Attix was considered. For CSDA range and radition yield the continuous slowing down approximation (CSDA) was considered and the calculations were performed using numerical integral methods. Because of their water equivalent and 3D dose distribution properties, MAGIC and MAGAS polymer gels were selected as a target materials. The calculations were performed by programming all the equations discribed in this study as a computational code. The results of the stopping power, range and radiation yield were compared with those of ESTAR program and PENELOPE Monte Carlo modelling. Some deviations in low and high energy region between the calculated and reference data were observed. However, the similarity between calculated and reference data is remarkable. For the collision stopping power and CSDA range a good agreement between the calculated and reference data was observed for energies >1 keV. Whereas, for the radiative stopping power a good agreement was observed for energies >100 keV.

Neutrinos and their interactions

We present a short overview of the importance of the study of neutrino interactions in the intermediate- and high-energy region, with an introduction to the neutrinos and a very brief description of the collection of invited articles.