Production and characterization of boron nanoparticles synthesized with a thermal plasma system

A new method for the production of boron nanoparticles is described. Boron trichloride is dissociated through injection into thermal plasma followed by a nucleation process producing boron nanoparticles. The ambient oxidation of the as-produced nanoparticles is also investigated. The nanoparticles were characterized with scanning transmission electron microscopy, electron energy loss spectroscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy to investigate their purity and stability under ambient conditions.     

Variational base and solution strategies for non-linear force-based beam finite elements

This paper presents the variational bases for the non-linear force-based beam elements. The element state determination of these elements is obtained exactly from a two-field functional with independent stress and strain fields. The variational base of the non-linear force-based beam elements implemented in a general purpose displacement-based finite element program requires the inclusion of independent displacement field in the formulation. For this purpose, a three-field functional is considered with independent displacement, stress, and strain fields. Various local and global solution strategies come out from the mixed formulation of the beam element, and these are shown to yield the algorithms presented for non-linear force formulation beam elements in literature; thus removing any doubts on their variational bases. The presented numerical examples demonstrate the accuracy and robustness of the solution algorithms adapted for mixed formulation elements over popularly used displacement-based beam finite elements even for large structural systems.     

On homology of real algebraic varieties

Let be a commutative ring with unity and an -oriented compact nonsingular real algebraic variety of dimension . If is any nonsingular complexification of , then the kernel, which we will denote by , of the induced homomorphism is independent of the complexification. In this work, we study and give some of its applications.

     

Ab-initio calculation of band structure and linear optical properties of SbSI in para- and ferroelectric phases

An ab-initio pseudopotential calculation has been performed by using density functional methods within the local density approximation (LDA) to investigate the band structure and optical properties of the ferroelectric-semiconductor SbSI in the para- and ferroelectric phases. It has been shown that SbSI has an indirect gap in both phases (1.45 eV and 1.49 eV in the para- and ferroelectric phases respectively) and that the smallest direct gap is at the S point of the Brillouin zone (1.56 eV and 1.58 eV in the para- and ferroelectric phases respectively). Furthermore, it is shown that first-order phase transition, from the paraelectric phase to the ferroelectric phase (the transiton temperature is about 22 °C), does not change the nature of the band gap. Moreover, the linear frequency dependent dielectric function, including self-energy effects, has been calculated along the c-polar axis in the para- and ferroelectric phases.      

Poly(iminoborane)s: An Elusive Class of Main‐Group Polymers?

The significance of inorganic main‐group polymers is demonstrated most clearly by the commercial relevance of polysiloxanes (silicones). Organoboron‐based materials such as π‐conjugated organoborane polymers and BN‐doped polycyclic aromatic hydrocarbons are currently attracting considerable attention. Surprisingly, poly(iminoborane)s (PIBs; [BRNR′]_n), that is, the parent unsaturated BN polymers, which are formally isoelectronic to polyacetylene, have not been convincingly characterized thus far. Herein, we present the synthesis and comprehensive characterization of a linear oligo(iminoborane), which comprises a chain of 12–14 BN units on average. With our synthetic approach, unwanted side reactions that result in borazine formation are effectively suppressed. Supporting DFT and TD‐DFT calculations provide deeper insight into the microstructure and the electronic structure of the oligomer.     

Two-dimensional quantum-spin-1/2 XXZ magnet in zero magnetic field: Global thermodynamics from renormalisation group theory

Phase diagram, critical properties and thermodynamic functions of the two-dimensional field-free quantum-spin-1/2 XXZ model has been calculated globally using a numerical renormalisation group theory. The nearest-neighbour spin-spin correlations and entanglement properties, as well as internal energy and specific heat are calculated globally at all temperatures for the whole range of exchange interaction anisotropy, from XY limit to Ising limits, for both antiferromagnetic and ferromagnetic cases. We show that there exists long-range (quasi-long-range) order at low-temperatures, and the low-lying excitations are gapped (gapless) in the Ising-like easy-axis (XY-like easy-plane) regime. Besides, we identify quantum phase transitions at zero-temperature.     

Improvement of cyclability of silicon-containing carbon nanofiber anodes for lithium-ion batteries by employing succinic anhydride as an electrolyte additive

Si/C composite nanofibers were prepared by electrospinning and carbonization using polyacrylonitrile as the spinning medium and carbon precursor. The effect of electrolyte additive succinic anhydride (SA) on the electrochemical performance of Si/C composite nanofiber anodes was investigated. Results show that after 50 cycles, the discharge capacity of Si/C composite nanofiber anode with the SA-added electrolyte is 34 % higher than that with additive-free electrolyte. At 150th cycle, the capacity retention of Si/C composite nanofiber anode with SA-added electrolyte is 82 % under 70 % state-of-charge. It is demonstrated that adding additive SA in the electrolyte is an effective and economic way to improve the cyclability of high-capacity Si/C composite nanofibers for next-generation high-energy lithium-ion batteries.     

Skew normal measurement error models

In this paper we define a class of skew normal measurement error models, extending usual symmetric normal models in order to avoid data transformation. The likelihood function of the observed data is obtained, which can be maximized by using existing statistical software. Inference on the parameters of interest can be approached by using the observed information matrix, which can also be computed by using existing statistical software, such as the Ox program. Bayesian inference is also discussed for the family of asymmetric models in terms of invariance with respect to the symmetric normal distribution showing that early results obtained for the normal distribution also holds for the asymmetric family. Results of a simulation study and an analysis of a real data set analysis are provided.     

On Homotopy Groups of Real Algebraic Varieties and their Complexifications

Let X ₀ be a topological component of a nonsingular real algebraic variety and i:X → X _C is a nonsingular projective complexification of X. In this paper, we will study the homomorphism on homotopy groups induced by the inclusion map i:X ₀ → X _C and obtain several results using rational homotopy theory and other standard tools of homotopy theory.