C-BN single-walled nanotubes from hybrid connection of BN/C nanoribbons : prediction by ab initio density functional calculations

We demonstrated for the first time by ab initio density functional calculation and molecular dynamics simulation that C0.5(BN)0.5 armchair single-walled nanotubes (NT) are gapless semiconductors and can be spontaneously formed via the hybrid connection of graphene/BN Nanoribbons (GNR/BNNR) at room temperature. The direct synthesis of armchair C0.5(BN)0.5 via the hybrid connection of GNR/BNNR is predicted to be both thermodynamically and dynamically stable. Such novel armchair C0.5(BN)0.5 NTs possess enhanced conductance as that observed in GNRs. Additionally, the zigzag C0.5(BN)0.5 SWNTs are narrow band gap semiconductors, which may have potential application for light emission. In light of recent experimental progress and the enhanced degree of control in the synthesis of GNRs and BNNR, our results highlight an interesting avenue for synthesizing a novel specific type of C0.5(BN)0.5 nanotube (gapless or narrow direct gap semiconductor), with potentially important applications in BNC-based nanodevices.

High-pressure structural transitions of Sc2O3 by X-ray diffraction, raman spectra, and ab initio calculations

The high-pressure behavior of scandium oxide (Sc₂O₃) has been investigated by angle-dispersive synchrotron powder X-ray diffraction and Raman spectroscopy techniques in a diamond anvil cell up to 46.2 and 42 GPa, respectively. An irreversible structural transformation of Sc₂O₃ from the cubic phase to a monoclinic high-pressure phase was observed at 36 GPa. Subsequent ab initio calculations for Sc₂O₃ predicted the phase transition from the cubic to monoclinic phase but at a much lower pressure. The same calculations predicted a second phase transition at 77 GPa from the monoclinic to hexagonal phase.

Ab initio calculations, Raman and NMR investigation of the plastic crystal di-methyl pyrrolidinium iodide

Above 110 °C the symmetric di-methyl-pyrrolidinium iodide salt forms a plastic crystal phase of interest in the area of new electrolyte materials. In this study ab initio calculations of this material has been conducted in order to assign the vibrational spectra. Raman spectroscopy measurements on the solid salt as well as on the salt dissolved in different solvents has been performed and these have been compared to the theoretical spectra. Furthermore, Raman spectra as a function of temperature have been recorded to investigate possible changes in inter-ionic interaction and/or structure through the phase transition. 1H NMR linewidth measurements as a function of temperature showed a large decrease in linewidth above 100 °C, attributed here to an increase in mobility in agreement with a previously reported phase transition at ~110 °C.

Fluorination-induced magnetism in boron nitride nanotubes from ab initio calculations

Ab initio calculations were conducted to investigate the electronic structures and magnetic properties of fluorinated boron nitride nanotube (F-BNNT). It was found that the chemisorption of F atoms on the B atoms of BNNT can induce spontaneous magnetization, whereas no magnetism can be produced when the B and N atoms are equally fluorinated. This provides a different approach to tune the magnetic properties of BNNTs as well as a synthetic route toward metal-free magnetic materials.

Estimating relative disulfide energies : an accurate ab initio potential energy surface

Disulfide torsional energy, a good predictor of disulfide redox potential in proteins, may be estimated by interpolation on a potential energy surface (PES) describing the twisting of diethyl disulfide through its three central dihedral angles. Here we update PES calculations at the M05-2X level of theory with the 6-31G(d) basis set. Although the surface shows no qualitative differences from an earlier MP2(full) PES, energy differences greater than 1 kJ mol^–1 were seen for conformations with χ₂ between –60° and 30°, or with χ₃ below 60° or above 130°. This is particularly significant for highly strained disulfides that are likely to be spontaneously reduced by mechanical means. In benchmarking against the high-level G3X method, M05-2X showed significantly reduced root mean squared deviation compared with MP2(full) (1.0 versus 2.0 kJ mol^–1 respectively). Results are incorporated into a web application that calculates relative torsional energies from disulfide dihedral angles (http://www.sbinf.org/applications/pes.html).

Structure and phase stability of NiMnGa ferromagnetic shape memory alloys by experimental and ab-initio techniques

This paper summarizes some of our recent results on crystal structure, microstructure, orientation relationship between martensitic variants and crystallographic features of martensitic transformation in Ni-Mn-Ga FSMAs. It was shown that Ni53Mn25Ga22 has a tetragonal I4/mmm martensitic structure at room temperature. The neighboring martensitic variants in Ni53Mn25Ga22 have a compound twinning relationship with the twinning elements K1={112}, K2={11-2}, η1=<11-1>, η2=<111>, P={1-10} and s=0.379. The ratio of the relative amounts of twins within the same initial austenite grain is ~1.70. The main orientation relationship between austenite and martensite is Kurdjumov-Sachs (K-S) relationship. Based on the crystallographic phenomenological theory, the calculated habit plane is {0.690 -0.102 0.716}A (5.95° from {101}A), and the magnitude, direction and shear angle of the macroscopic transformation shear are 0.121, <-0.709 0.105 0.698>A (6.04° from <-101>A) and 6.88°, respectively.

Half metallicity in a zigzag double-walled nanotube nanodot : an ab initio prediction

Ab initio density functional calculations were performed to study finite-length zigzag (7, 0) @ (16, 0) double-walled carbon nanotubes (DWCNTs) with H-termination at the open ends. We find that such a DWCNT nanodot displays a very large magnetic moment at the zigzag edges and the ground state displays symmetric anti-ferromagnetic coupling. When an external electric field is applied along the direction of tube axis, a gap is opened for one spin channel, whereas another spin channel remains metallic, i.e. half metallicity occurs. Our results suggest an important new avenue for the development of CNT-based spintronic materials with enhanced properties. © 2008 Elsevier B.V. All rights reserved.

Electrochemical and quantum chemical assessment of two organic compounds from pyridine derivatives as corrosion inhibitors for mild steel in HCl solution under stagnant condition and hydrodynamic flow

 In this study, the inhibitive performance of two pyridine derivatives as corrosion inhibitors for mild steel was examined under stagnant condition and hydrodynamic flow in HCl solution at 25. °C. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques were employed. To explore the inhibitors adsorption mechanism, Langmuir isotherm and quantum chemical studies were used. The results of electrochemical measurements show that the inhibitor concentration has a positive effect on its efficiency while for hydrodynamic condition, it is vice versa. Corrosion attack morphologies were observed at stagnant and hydrodynamic conditions to verify qualitatively the results obtained by electrochemical methods. © 2013 Elsevier Ltd.

Studies on the mechanism of the peroxyoxalate chemiluminescence reaction Part 1. Confirmation of 1,2-dioxetanedione as an intermediate using 13C nuclear magnetic resonance spectroscopy

A simple model peroxyoxalate chemiluminescence system was monitored directly across a range of temperatures (from −80 to +20 °C) using ¹³C nuclear magnetic resonance spectroscopy. These experiments were made possible by the utilisation of ¹³C doubly labelled oxalyl chloride, which was reacted with anhydrous hydrogen peroxide in dry tetrahydrofuran. Ab initio quantum calculations were also performed to estimate the ¹³C nuclear magnetic resonance (NMR) shift of the most commonly postulated key intermediate 1,2-dioxetanedione and this data, in concert with the spectroscopic evidence, confirmed its presence during the reaction.

A method and its optimal parameters for the measurement of mass transfer coefficient in heat treatment furnaces

The mass transfer coefficient is an important kinetic factor to control the thermo-chemical treatment processes of metals and alloys. More importantly, the mass transfer coefficient is different at different surface positions of a metallic part treated, which depends on the dynamic characteristics of the atmosphere close to the treated surface. Understanding the local mass transfer coefficient would be significant to approach the expected physical and mechanical properties of treated surfaces. In this paper, a reverse method was proposed to measure the mass transfer coefficient at component surface and the diffusivity in metal during heat treatment. The methodology of the reverses method and the optimal parame-ters are discussed in some detail. This method was successfully used to determine the car-bon transfer coefficient at the surface of a part in a carburizing furnace and carbon diffusiv-ity from the carbon distribution within the diffusion layer.

Discrimination of origin of farmed trout by means of biometrical parameters, fillet chemical composition and flavour volatile compounds

To date it is well known that the quality of farmed trout is affected by diet composition, by feeding regime, by husbandry practices and by rearing conditions and environment. The trout processing industry and the large-scale retail trade, in consideration of the wide variability of trout quality and characteristics, have imposed, or will soon impose, quality criteria for the end product. Moreover, recent food scares and the malpractices of some food producers have increased public requests
for traceability. The aim of the present study was to evaluate the main chemical quality and the biometrical characteristics of rainbow trout produced in three different farms in Italy (two intensive farms, located one on mountain and one on plain, and an extensive farm in which fish fed only on naturally available nutrients) and to establish whether farmed trout
origins could be differentiated by these parameters. Trout farmed in the intensive mountain farm (IMF) showed the highest crude lipid content in the fillets and the fatty acids of their fillets were characterized by the highest percentage of MUFA. Trout farmed in the intensive plain farm (IPF) were characterized by low dressing percentage, and the lipid of their fillets
was rich in n-6 fatty acids. Trout stocked for the last year of their life in the extensive farm (EF) were leaner both in the carcass and in the fillets. The analysis of flavor volatile compounds showed some differences in the bouquet design, particularly differences in the amounts of n-3 and n-6 derivates volatile aldehydes and alcohols. All data significantly different
(P<0.05) were subjected to Linear Discriminant Analysis (LDA) and 8 variables were chosen to create two discriminant equations generating a strong prediction model for classification of farmed trout respective to their origins.

Creative arts practice, creative industries : method and process as cultural capital

The value of artistic research is related not only to the products of creative arts practices, but also to methodological, material and social processes through which they operate.

This paper argues that although creative arts research methods – the use of personally situated, interdisciplinary and emergent approaches – contradict what is usually expected of research, such approaches underpin the innovative capacity of studio enquiry and its implication for extending practice-led research pedagogy across all research disciplines.