Raman spectroscopic study of the mineral shattuckite Cu5(SiO3)4(OH)2

Shattuckite Cu5(SiO3)4(OH)2 is a copper hydroxy silicate and is commonly known as a ‘healing’ mineral. Three shattuckite mineral samples from three different origins were analysed by Raman spectroscopy. Some Raman bands are common in the spectra of the minerals. Raman bands at around 890, 1058 and 1102 are described as the ν3 –SiO3 antisymmetric stretching vibrations. The Raman band at 670 cm-1 is assigned to the ν4 bending modes of the -SiO3 units and the band at around 785 cm-1is due to Si-O-Si chain stretching mode. Raman (and infrared) spectroscopy proves that water is in the molecular structure of shattuckite; thus the formula is better written as Cu5(SiO3)4(OH)2•xH2O.

Effective shear modulus approach for two dimensional solids and plate bending problems by meshless point collocation method

For the analysis of material nonlinearity, an effective shear modulus approach based on the strain control method is proposed in this paper by using point collocation method. Hencky’s total deformation theory is used to evaluate the effective shear modulus, Young’s modulus and Poisson’s ratio, which are treated as spatial field variables. These effective properties are obtained by the strain controlled projection method in an iterative manner. To evaluate the second order derivatives of shape function at the field point, the radial basis function (RBF) in the local support domain is used. Several numerical examples are presented to demonstrate the efficiency and accuracy of the proposed method and comparisons have been made with analytical solutions and the finite element method (ABAQUS).

Central Queensland Mining Supplies Pty Ltd v Columbia Steel Casting Co Ltd

In Central Queensland Mining Supplies Pty Ltd v Columbia Steel Casting Co Ltd [2011] QSC 183 Applegarth J considered complaints made by the defendant about the approach the plaintiff had taken in its endeavour to comply with its disclosure obligation under r 211 of the Uniform Civil Procedure Rules 1999 (Qld). The judgment also provides an indication of the direction the court is taking in relation to disclosure and document management in matters involving large numbers of documents.

Plastic bending behaviour and section moment capacities of mono-symmetric LiteSteel Beams with web openings

Recently developed cold-formed LiteSteel beam (LSB) sections have found increasing popularity in residential, industrial and commercial buildings due to their light weight and cost-effectiveness. Currently, there is significant interest in the use of LSB sections as flexural members in floor joist systems, although they can be used as flexural and compression members in a range of building systems. The plastic bending behaviour and section moment capacity of LSB sections with web holes can be assumed to differ from those without, but have yet to be investigated. Hence, no appropriate design rules for determining the section moment capacity of LSB sections with web holes are yet available. This paper presents the results of an investigation of the plastic bending behaviour and section moment capacity of LSB sections with circular web holes. LSB sections with varying circular hole diameters and degrees of spacing were considered. The paper also describes the simplified finite element (FE) modelling technique employed in this study, which incorporates all of the significant behavioural effects that influence the plastic bending behaviour and section moment capacity of these sections. The numerical and experimental test results and associated findings are also presented.

Inelastic bending capacity of LiteSteel Beams

Australian manufacturers recently developed a new mono-symmetric cold-formed steel hollow flange channel section known as LiteSteel Beam. The innovative LSB sections with rectangular flanges are currently being used as floor joists and bearers in buildings. In order to assess their behaviour and section moment capacity including the presence of any inelastic reserve bending capacity, 20 section moment capacity tests were conducted in this study. Test results were compared with the section moment capacities predicted by the steel design codes. Although the current cold-formed steel design rules generally limit the section moment capacities to their first yield moments, test results showed that inelastic reserve bending capacity was present in the compact and non-compact LSB sections. The results have shown that suitable modifications to the current design rules are needed to allow the inclusion of available inelastic bending capacities of LSBs in design.

A vibrational spectroscopic study of the phosphate mineral Wardite NaAl3(PO4)2(OH)4•2(H2O)

Three wardite mineral samples from different origins have been analysed by vibrational spectroscopy. The mineral is unusual in that it belongs to a unique symmetry class, namely the tetragonal-trapezohedral group. The structure of wardite contains layers of corner-linked –OH bridged MO6 octahedra stacked along the tetragonal C-axis in a four-layer sequence and linked by PO4 groups. Consequentially not all phosphate units are identical. Thus, two intense Raman bands observed at 995 and 1051 cm-1 are assigned to the ν1 PO43- symmetric stretching mode. Intense Raman bands are observed at 605 and 618 cm-1 with shoulders at 578 and 589 cm-1 are assigned to the ν4 out of plane bending modes of the PO43-. The observation of multiple bands supports the concept of non-equivalent phosphate units in the structure. Sharp infrared bands are observed at 3544 and 3611 cm-1 are attributed to the OH stretching vibrations of the hydroxyl units. Vibrational spectroscopy enables subtle details of the molecular structure of wardite to be determined.

Is the mineral borickyite (Ca,Mg)(Fe3+,Al)4(PO4,SO4,CO3)(OH)8•3-7.5H2O the same as delvauxite CaFe3+4(PO4,SO4)2(OH)8•4-6H2O?

The two minerals borickyite and delvauxite CaFe3+4(PO4,SO4)2(OH)8•4-6H2O have the same formula. Are the minerals identical or different? The minerals borickyite and delvauxite have been characterised by Raman spectroscopy. The minerals are related to the minerals diadochite and destinezite. Both minerals are amorphous. Delvauxite appears to vary in crystallinity from amorphous to semi-crystalline. The minerals are often X-ray non-diffracting. The minerals are found in soils and may be described as ‘colloidal’ minerals. Vibrational spectroscopy enables an assessment of the molecular structure of borickyite and delvauxite. Bands are assigned to phosphate and sulphate stretching and bending modes. Multiple water bending and stretching modes imply that non-equivalent water molecules in the structure exist with different hydrogen bond strengths. The two minerals show differing spectra and must be considered as different minerals.

Modified beam theories for bending properties of nanowires considering surface/intrinsic effects and axial extension effect

Several studies of the surface effect on bending properties of a nanowire (NW) have been conducted. However, these analyses are mainly based on theoretical predictions, and there is seldom integration study in combination between theoretical predictions and simulation results. Thus, based on the molecular dynamics (MD) simulation and different modified beam theories, a comprehensive theoretical and numerical study for bending properties of nanowires considering surface/intrinsic stress effects and axial extension effect is conducted in this work. The discussion begins from the Euler-Bernoulli beam theory and Timoshenko beam theory augmented with surface effect. It is found that when the NW possesses a relatively small cross-sectional size, these two theories cannot accurately interpret the true surface effect. The incorporation of axial extension effect into Euler-Bernoulli beam theory provides a nonlinear solution that agrees with the nonlinear-elastic experimental and MD results. However, it is still found inaccurate when the NW cross-sectional size is relatively small. Such inaccuracy is also observed for the Euler-Bernoulli beam theory augmented with both contributions from surface effect and axial extension effect. A comprehensive model for completely considering influences from surface stress, intrinsic stress, and axial extension is then proposed, which leads to good agreement with MD simulation results. It is thus concluded that, for NWs with a relatively small cross-sectional size, a simple consideration of surface stress effect is inappropriate, and a comprehensive consideration of the intrinsic stress effect is required.

Influence of plate bending stiffness on mechanical properties of healing fracture, mouse femora

Mechanically well-defined stabilization systems have only recently become available, providing standardized conditions for studying the role of the mechanical environment on mouse bone fracture healing. The aim of this study was to characterize the time course of strength recovery and callus development of mouse femoral osteotomies stabilized with either low or high flexibility (in bending and torsion) internal fixation plates. Animals were euthanized and femora excised at 14, 21, and 28 days post-osteotomy for microCT analysis and torsional strength testing. While a larger mineralized callus was observed in osteotomies under more flexible conditions at all time points, the earlier bridging of the mineralized callus under less flexible conditions by 1 week resulted in an earlier recovery of torsional strength in mice stabilized with low flexibility fixation. Ultimate torque values for these bones were significantly higher at 14 and 21 days post-osteotomy compared to bones with the more flexible stabilization. Our study confirms the high reproducibility of the results that are achieved with this new implant system, therefore making it ideal for studying the influence of the mechanical environment on murine fracture healing under highly standardized conditions.

Coupling of energy from quantum emitters to the plasmonic mode of V groove waveguides: A numerical study

This work is a theoretical investigation into the coupling of a single excited quantum emitter to the plasmon mode of a V groove waveguide. The V groove waveguide consists of a triangular channel milled in gold and the emitter is modeled as a dipole emitter, and could represent a quantum dot, nitrogen vacancy in diamond, or similar. In this work the dependence of coupling efficiency of emitter to plasmon mode is determined for various geometrical parameters of the emitter-waveguide system. Using the finite element method, the effect on coupling efficiency of the emitter position and orientation, groove angle, groove depth, and tip radius, is studied in detail. We demonstrate that all parameters, with the exception of groove depth, have a significant impact on the attainable coupling efficiency. Understanding the effect of various geometrical parameters on the coupling between emitters and the plasmonic mode of the waveguide is essential for the design and optimization of quantum dot–V groove devices.

Raman spectroscopic study of the minerals apophyllite-(KF) KCa4Si8O20F.8H2O and apophyllite-(KOH) KCa4Si8O20(F,OH).8H2O

Raman spectroscopy complimented with infrared spectroscopy has been used to study the variation in molecular structure of two minerals of the apophyllite mineral group, namely apophyllite-(KF)KCa4Si8O20F.8H2O and apophyllite-(KOH) KCa4Si8O20(F,OH).8H2O. apophyllite-(KF) and apophyllite-(KOH) are different minerals only because of the difference in the percentage of fluorine to hydroxyl ions. The Raman spectra are dominated by a very intense sharp peak at 1059 cm -1. A band at around 846 cm -1 is assigned to the water librational mode. It is proposed that the difference between apophyllite-(KF) and apophyllite-(KOH) is the observation of two Raman bands in the OH stretching region at around 3563 and 3625 cm -1. Multiple water stretching and bending modes are observed showing that there is much variation in hydrogen bonding between water and the silicate surfaces.

Tests of LiteSteel Beams subject to combined shear and bending actions

This paper presents the details of an experimental study of a cold-formed steel beam known as LiteSteel Beam (LSB) subject to combined shear and bending actions. The LSBs have the beneficial characteristics of torsionally rigid rectangular hollow flanges combined with economical fabrication processes from a single strip of high strength steel. They combine the stability of hot-rolled steel sections with the high strength to weight ratio of conventional cold-formed steel sections. The LSB sections are commonly used as flexural members in residential, industrial and commercial buildings. In order to ensure safe and efficient designs of LSBs, many research studies have been undertaken on the flexural and shear strengths of LSBs. To date, however, no investigation has been conducted into the strength of LSB sections under combined shear and bending actions. Hence a detailed experimental study involving 18 tests was undertaken to investigate the behaviour and strength of LSBs under combined shear and bending actions. Test results showed that AS/NZS 4600 design rules for unstiffened webs grossly underestimated the capacity of LSBs. Therefore improved design equations were proposed for the combined shear and bending capacities of LSBs based on experimental results.

Behaviour of LiteSteel beams subject to combined shear and bending actions

This paper presents the details of a numerical study of a cold-formed steel beam known as LiteSteel Beam (LSB) subject to combined shear and bending actions. The LSB sections are produced by a patented manufacturing process involving simultaneous cold-forming and electric resistance welding. They have a unique shape of a channel beam with two rectangular hollow flanges. To date, however, no investigation has been conducted into the strength of LSB sections under combined shear and bending actions. Hence a numerical study was undertaken to investigate the behaviour and strength of LSBs subject to combined shear and bending actions. In this research, finite element models of LSBs were developed to simulate the combined shear and bending behaviour and strength of LSBs. They were then validated by comparing their results with test results and used in a parametric study. Both experimental and finite element analysis results showed that the current design equations are not suitable for combined shear and bending capacities of LSBs. Hence improved design equations are proposed for the capacities of LSBs subject to combined shear and bending actions.