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Full-Text Articles in Physical Sciences and Mathematics

Magnetocaloric Properties Of Co/Cr Superlattices, Tathagata Mukherjee, Sarbeswar Sahoo, David J. Sellmyer, Christian Binek Apr 2009

Magnetocaloric Properties Of Co/Cr Superlattices, Tathagata Mukherjee, Sarbeswar Sahoo, David J. Sellmyer, Christian Binek

Christian Binek Publications

Nanostructured materials for refrigeration applications are experimentally realized by molecular beam epitaxial growth of Co/Cr superlattices using mean-field theoretical concepts as guiding principles. Magnetocaloric properties are deduced from measurements of the temperature and field dependence of the magnetization of our samples. More generally, the potential of artificial antiferromagnets for near room-temperature refrigeration is explored. The effects of intraplane and interplane exchange interactions on the magnetic phase diagram in Ising-type model systems are revisited in mean-field considerations with special emphasis on tailoring magnetocaloric properties. The experimental results are discussed in light of our theoretical findings, and extrapolations for future improved nanostructures …


Electronic Properties Of Silicon Nanotubes With Distinct Bond Lengths, James M. Hill, J E. Bunder Jan 2009

Electronic Properties Of Silicon Nanotubes With Distinct Bond Lengths, James M. Hill, J E. Bunder

Faculty of Informatics - Papers (Archive)

We analyze the band structure of a silicon nanotube with sp^3 bonds and variable bond lengths. This nanotube has many similarities with a carbon nanotube including a band gap at half-filling and conducting behavior which is dependent on structure. We derive a simple formula which predicts when the nanotube is metallic. We discuss our results in the context of a nanotube subject to small applied strains as this provides a means of distorting bond lengths in a predictable way and may be tested experimentally. The affects of strain on nanotube conductance has important implications for sensor technology.


Synthesis And Ph-Responsive Properties Of Pseudo-Peptide Containing Hydrophobic Amino Acid Grafts, Rongjun Chen, Mark E. Eccleston, Zhilian Yue, Nighel K. H Slater Jan 2009

Synthesis And Ph-Responsive Properties Of Pseudo-Peptide Containing Hydrophobic Amino Acid Grafts, Rongjun Chen, Mark E. Eccleston, Zhilian Yue, Nighel K. H Slater

Faculty of Science - Papers (Archive)

Pseudo-peptidic polymers have been synthesised by grafting l-valine (PV), l-leucine (PL) and l-phenylalanine (PP) onto the pendant carboxylic acid moieties of a pH-responsive polyamide, poly(l-lysine isophthalamide). The pH-responsive aqueous solution properties of PV-75, PL-75 and PP-75 with a stoichiometric degree of substitution of 75 mol% have been compared with those of the parent poly(l-lysine isophthalamide) using UV-visible and fluorescence spectroscopy. At low concentrations (≤0.1 mg mL-1), the grafted polymers displayed pH-dependent conformation. The pH at the onset of hydrophobic association (pHh) and the pH range over which association occurred varied significantly between the different amino acid grafts. The pHh values …


The Effect Of Preparation Conditions And Biopolymer Dispersants On The Properties Of Swnt Buckypapers, Jenny Boge, Luke J. Sweetman, Marc In Het Panhuis, Stephen F. Ralph Jan 2009

The Effect Of Preparation Conditions And Biopolymer Dispersants On The Properties Of Swnt Buckypapers, Jenny Boge, Luke J. Sweetman, Marc In Het Panhuis, Stephen F. Ralph

Faculty of Science - Papers (Archive)

The effect of varying preparation conditions on the properties of buckypapers made using single-walled carbon nanotubes (SWNTs) was systematically investigated. Changing the sonication time, final dispersion volume or membrane filter used to prepare SWNT-Triton X-100 buckypapers all generally had only a small influence on the density, thickness, contact angle and electrical conductivity of the resulting material. More significant changes were noted when the effects of variations in the above preparation conditions on the mechanical properties and surface morphology of SWNT-Triton X-100 buckypapers were investigated. However, the largest changes in properties were found when various biopolymers (bovine serum albumin, lysozyme, gellan …


Room Temperature Multiferroic Properties Of Nd: Bifeo3/Bi2femno6 Bilayered Films, Hongyang Zhao, Hideo Kimura, Zhenxiang Cheng, Xiaolin Wang, Takashi Nishida Jan 2009

Room Temperature Multiferroic Properties Of Nd: Bifeo3/Bi2femno6 Bilayered Films, Hongyang Zhao, Hideo Kimura, Zhenxiang Cheng, Xiaolin Wang, Takashi Nishida

Australian Institute for Innovative Materials - Papers

Nd0.1Bi0.9FeO3 /Bi2FeMnO6 bilayered films were deposited on Pt/Ti/SiO2 / Si substrate by pulsed laser deposition method. BiFeO3 is antiferromagnet while BiMnO3 is ferromagnet, the ordering of –Mn–O–Fe–O–Mn– is expected, which will induce the ferromagnetic interation in the film. The film shows typical ferromagnetic properties with the transition temperature of Tc of 440 K. The room temperature (RT) ferroelectric polarization was also observed, suggesting that the film is a promising RT multiferroism.


Investigations Of Electrochemical And Spectroelectrochemical Properties (Uv-Vis, Epr) Of Thiophene Trimer Derivatives Substituted With Phenylvinyl Groups., Pawel W. Wagner, Agnieszka Stolarczyk, Mariola Bartoszek, Mieczyslaw Lapkowski, David L. Officer, Keith C. Gordon, M Jadamiec, Wieslaw W. Sulkowski Jan 2009

Investigations Of Electrochemical And Spectroelectrochemical Properties (Uv-Vis, Epr) Of Thiophene Trimer Derivatives Substituted With Phenylvinyl Groups., Pawel W. Wagner, Agnieszka Stolarczyk, Mariola Bartoszek, Mieczyslaw Lapkowski, David L. Officer, Keith C. Gordon, M Jadamiec, Wieslaw W. Sulkowski

Faculty of Science - Papers (Archive)

The results of investigations concerning electrochem. properties of two thiophene trimers derivs. substituted with phenylvinyl groups {3'[(E)-2-phenylethenyl]-2,2':5',2"-thiophene (monomer A) and 4,4"-didecyloxy-3'[(E)-2-phenylethenyl]-2,2':5',2"-thiophene (monomer B)} and the products of their oxidn. were discussed. Electropolymns. of A and B monomers were carried out with use of cyclic voltammetry and electrochem. measurements were coupled in-situ with spectroscopic methods (UV-Vis, EPR). It was found that A monomer oxidized to oligomers sol. in dichloromethane while monomer B showed ability to form stable conductive polymer layers showing low-energy forbidden band (1.6 eV).


The Major Toxin From The Australian Common Brown Snake Is A Hexamer With Unusual Gas-Phase Dissociation Properties, Andrew Aquilina Jan 2009

The Major Toxin From The Australian Common Brown Snake Is A Hexamer With Unusual Gas-Phase Dissociation Properties, Andrew Aquilina

Faculty of Science - Papers (Archive)

Asymmetric dissociation of multiply charged proteins assemblies has been frequently reported. This phenomenon, which relies on the dissociation of one or more highly charged monomers, has been shown to provide insights into the structure and organization of large monodisperse and polydisperse assemblies. Here, the process of asymmetric dissociation is investigated using the multi-subunit protein, textilotoxin, which has unusually high structural constraints on its monomers due to multiple disulfide linkages. Initially, it is shown that, contrary to previous reports, textilotoxin is made up of 6, rather than 5 subunits. Furthermore, the hexamer exists as two isoforms, one of which is substantially …


Fabrication And Superconducting Properties Of Highly Dense Mgb2 Bulk Using A Two-Step Sintering Method, Minoru Maeda, Yue Zhao, Yoshifumi Watanabe, Hiroaki Matsuoka, Y Kubota Jan 2009

Fabrication And Superconducting Properties Of Highly Dense Mgb2 Bulk Using A Two-Step Sintering Method, Minoru Maeda, Yue Zhao, Yoshifumi Watanabe, Hiroaki Matsuoka, Y Kubota

Australian Institute for Innovative Materials - Papers

We investigated on microstructure and superconducting properties of high-density MgB2superconductors synthesized by a heat-treatment method combining a short period of sintering at 1100°C with a following annealing at a low temperature. The two-step sintering method was found to achieve a coexistence of a high density and broadened XRD full width at half maximum (FWHM) of MgB2 peak in the samples. The onset of diamagnetism at 5 T was approximately 2 K higher than those of the samples heat-treated by single-step sintering at high or low temperatures. Different second-step annealing temperatures were examined in this work. …


Crystal Structure And Electronic And Thermal Properties Of Tbfeaso0.85, N Kaurav, Y.T Chung, Y.K Kuo, R S Liu, T S Chan, J.M Chen, J.F Lee, H.S Sheu, Xiaolin Wang, S X. Dou, Sung-Ik Lee, Y.G Shi, A.A Belik, K Yamaura, E Takayama-Muromachi Jan 2009

Crystal Structure And Electronic And Thermal Properties Of Tbfeaso0.85, N Kaurav, Y.T Chung, Y.K Kuo, R S Liu, T S Chan, J.M Chen, J.F Lee, H.S Sheu, Xiaolin Wang, S X. Dou, Sung-Ik Lee, Y.G Shi, A.A Belik, K Yamaura, E Takayama-Muromachi

Australian Institute for Innovative Materials - Papers

The crystal structure and the electronic and thermal properties of a high-quality polycrystalline TbFeAsO0.85 sample made by a high-pressure technique are investigated. The crystal structure, as determined by synchrotron X-ray powder diffraction, possesses a tetragonal unit cell (space group: P4/nmm) with lattice parameters of a=b=3.8851 Å and c =8.3630 Å. In order to elucidate the electronic structure and oxidation states of corresponding elements, X-ray absorption near-edge structure (XANES) spectra are presented. The XANES spectra confirm that the oxidation states of Fe, As, and Tb in the TbFeAsO0.85 sample are ~Fe2+, …


Problems Of Local Fractional Definite Integral Of The One-Variable Non-Differentiable Function, Yang Xiao-Jun Dec 2008

Problems Of Local Fractional Definite Integral Of The One-Variable Non-Differentiable Function, Yang Xiao-Jun

Xiao-Jun Yang

It is proposed that local fractional calculas introduced by Kolwankar and Gangal is extended by the concept of Jumarie’s fractional calculus and local fractional definite integral is redefined. The properties and the theorems of local fractional calculus are discussed in this paper.