High-energy-density pentazolate salts: CaN_(10) and BaN_(10)

The search for high energy density materials(HEDMs)in polymeric nitrogen compounds has gained considerable attention.Previous theoretical predictions and experiments have revealed that metal ions can be used to stabilize the pentazolate(N-5)anion.In this work,by employing a machine learning-accelerated crystal structure searching method and first-principles calculations,we found that the new pentazolate salts,CaN(10)and BaN(10),are energetically favorable at high pressures.Phonon dispersion calculations reveal that they are quenchable at ambient pressure.Ab initio molecular dynamics simulations verify their dynamic stability at finite temperature.Bader charge and electron localization function illustrates that alkaline earth atoms serve as electron donors,contributing to the stability of N5 rings.Bonding calculations reveal covalent bonds between nitrogen atoms and weak interactions between N5 rings.Similar to other pentazolate salts,these polymeric nitrides have high energy densities of approximately 2.35 kJ/g for CaN(10)and 1.32 kJ/g for BaN(10).The predictions of CaN(10)and BaN(10)structures indicate that these salts are potential candidates for green nitrogen-rich HEDMs.     

Flipped SO(10)

We constract an N = 1 supersymmetric SO(10) GUT broken down to SU(3)_c×SU(2)_L×U(1)_Y with an intermediate flipped SU(5)×U(1)_X gauge symmetry. A solution to the triplet-doublet mass-splitting problem is proposed in terms of a non-minimal missing-partner mechanism.     

SO(10) v ×SO(10) H grand unified-extended technicolour models

We discuss a recently proposedSO(10) _v ×SO(10) _H grand unified-extended technicolour model. Because proton decay is probably too fast in this model, we study the other possible models based onSO(10) _v ×SO(10) _H . As a result of this analysis only a few of these models could possibly be realistic, they would be slight modifications of that previously proposed. None of them predicts the expected value forΛ _TC, it must be adjusted by introducing another mass scale. In these models ordinary fermion masses tend to be too small.     

Light lepto-quarks inSO(10)

It is shown that a particular chain of symmetry breaking inSO(10) theory which leads to a standard picture of low energy phenomena, allows the scale ofSU (4) _c quark-lepton symmetry breaking to be as low as 10⁵–10⁶ GeV. This, among other predictions, gives rise to rare kaon decays with \(B(K_L \to \bar \mu e) \cong 10^{ - 9} - 10^{ - 13} \) and proton lifetime in the range 10³¹–10³⁴ years. Also, there exist the second neutral gauge boson and right-handed neutrinos with masses in the range: few hundred-10⁵ GeV.     

Preons and SO(10)

Two composite models based on SO(10) are explored, the first containing a fermion and a scalar each in the 16 rep, the second containing two fermion reps 10 + 16. The second model contains a massless composite fermion in the confined picture with a Higgs picture interpretation.     

Dynamic mechanical relaxation and thermal creep of high-entropy La_(30)Ce_(30)Ni_(10)Al_(20)Co_(10) bulk metallic glass

Dynamic mechanical relaxation is a fundamental tool to understand the mechanical and physical properties of viscoelastic materials like glasses. Mechanical spectroscopy shows that the high-entropy bulk metallic glass(La_(30)Ce_(30)Ni_(10)Al_(20)Co_(10)) exhibits a distinct β-relaxation feature. In the present research, dynamic mechanical analysis and thermal creep were performed using this bulk metallic glass material at a temperature domain around the β relaxation. The components of total strain, including ideal elastic strain, anelastic strain, and viscous-plastic strain, were analyzed based on the model of shear transformation zones(STZs).The stochastic activation of STZ contributes to the anelastic strain. When the temperature or external stress is high enough or the timescale is long enough, the interaction between STZs induces viscous-plastic strain. When all the spectrum of STZs is activated, the quasi-steady-state creep is achieved.     

Nuclear Algebraic Geometry and SO(10)

In this contribution nuclear representations of the Dirac ring, developed over many years, are shown to be a particular case of a theorem in algebraic geometry which at the same time associates them with a Hodge decomposition of a Kaehler manifold. This yields a shape that in some cases is independent of any appeal to a symmetry group. However, because the nuclear representations are in the infinitesimal ring of SO(4) and the internal space of each representation is in a Kaehler (even Calabi-Yau) manifold K; the group SO(10) = SO(4) × K can give additional information. This paper develops the very fruitful symbiosis between algebra and irreducible representations of SO(10) and covers some aspects of string theory.     

The neutrino see-saw in SO(10)

When a predictive and apparently realistic model for the quark mass matrices is extended to the leptons by using an SO(10) framework, it is found that the mass matrix of heavy “right-handed” neutrinos is likely to be close to a singular one. This may result in a variety of interesting patterns for the neutrino masses which are analyzed and compared with experiment.     

Spontaneous symmetry breaking in O(10)

We consider the most general renormalizable O(10) invariant potential for a $\text{45 + 16 +}\text{16}$ representation of Higgs fields. We show that O(10) can be spontaneously broken down to SU(5), SU(4) × U(1) or SU(3) × SU(2) × U(1), this last case being, of course, the most appealing.     

An SO(10) model with 54 + 126 + 10 higgs

We find an absolute minimum of an SO(10) symmetric potential with SU(3) × U(1) invariance. By fixing the higher scales M_R(〈126〉) ? M_x(〈54〉), the model is consistent with the experimental knowledge about matter stability and the value of sin²θ_w. We determine the spectrum of scalar particles and show that their tree-diagram contributions to nucleon decay amplitudes are proportional to 1/M_x².     

Weak carrier localization on the (10\bar 10) tellurium surface

A theory of weak localization responsible for the negative magnetoresistance effect is developed for quantum wells at the tellurium surface, which retains, in contrast to the surface considered earlier, a trigonal spectrum distortion with opposite signs near the M and P extrema, with the latter playing the part of states with opposite spins. It is shown that as a result of the motion in momentum and spin spaces being correlated the spin relaxation due to this distortion is smaller than that for the (0001) surface. Fiz. Tverd. Tela (St. Petersburg) 39, 1659–1664 (September 1997)     

Evidence for changing of cosmic ray composition between 10(17) and 10(18) eV from multicomponent measurements

The average mass composition of cosmic rays with primary energies between 10(17) and 10(18) eV has been studied using a hybrid detector consisting of the High Resolution Fly's Eye (HiRes) prototype and the MIA muon array. Measurements have been made of the change in the depth of shower maximum and the muon density as a function of energy. The results show that the composition is changing from a heavy to lighter mix as the energy increases.     

Coadsorption of silicon and chalcogen (S, O) atoms on heated Re(10\bar 10) substrate

The coadsorption of silicon and Group VI elements on the Re $(10\bar 10)$ surface is investigated by the 1 high-resolution Auger spectroscopy. It is demonstrated that, upon deposition of silicon on the surface oxide or surface sulfide, a part of silicon atoms deposited interacts with chalcogen atoms to be desorbed in the form of SiO or SiS molecules. The rest of silicon atoms occupy the becoming free adsorption sites, thus forming surface silicide. The silicon atoms incorporated into the surface silicide loose their reactivity and coexist on the surface together with adsorbed chalcogen atoms.