Efficient solution of two-sided nonlinear space-fractional diffusion equations using fast Poisson preconditioners

We develop a fast Poisson preconditioner for the efficient numerical solution of a class of two-sided nonlinear space fractional diffusion equations in one and two dimensions using the method of lines. Using the shifted Gr¨unwald finite difference formulas to approximate the two-sided(i.e. the left and right Riemann-Liouville) fractional derivatives, the resulting semi-discrete nonlinear systems have dense Jacobian matrices owing to the non-local property of fractional derivatives. We employ a modern initial value problem solver utilising backward differentiation formulas and Jacobian-free Newton-Krylov methods to solve these systems. For efficient performance of the Jacobianfree Newton-Krylov method it is essential to apply an effective preconditioner to accelerate the convergence of the linear iterative solver. The key contribution of our work is to generalise the fast Poisson preconditioner, widely used for integer-order diffusion equations, so that it applies to the two-sided space fractional diffusion equation. A number of numerical experiments are presented to demonstrate the effectiveness of the preconditioner and the overall solution strategy.

A banded preconditioner for the two-sided, nonlinear space-fractional diffusion equation

The method of lines is a standard method for advancing the solution of partial differential equations (PDEs) in time. In one sense, the method applies equally well to space-fractional PDEs as it does to integer-order PDEs. However, there is a significant challenge when solving space-fractional PDEs in this way, owing to the non-local nature of the fractional derivatives. Each equation in the resulting semi-discrete system involves contributions from every spatial node in the domain. This has important consequences for the efficiency of the numerical solver, especially when the system is large. First, the Jacobian matrix of the system is dense, and hence methods that avoid the need to form and factorise this matrix are preferred. Second, since the cost of evaluating the discrete equations is high, it is essential to minimise the number of evaluations required to advance the solution in time. In this paper, we show how an effective preconditioner is essential for improving the efficiency of the method of lines for solving a quite general two-sided, nonlinear space-fractional diffusion equation. A key contribution is to show, how to construct suitable banded approximations to the system Jacobian for preconditioning purposes that permit high orders and large stepsizes to be used in the temporal integration, without requiring dense matrices to be formed. The results of numerical experiments are presented that demonstrate the effectiveness of this approach.

Flexural performance of an innovative Hybrid Composite Floor Plate System comprising Glass–fibre Reinforced Cement, Polyurethane and steel laminate

This study explored the flexural performance of an innovative Hybrid Composite Floor Plate System (HCFPS), comprised of Polyurethane (PU) core, outer layers of Glass-fibre Reinforced Cement (GRC) and steel laminates at tensile regions, using experimental testing and Finite Element (FE) modelling. Bending and cyclic loading tests for the HCFPS panels and a comprehensive material testing program for component materials were carried out. HCFPS test panel exhibited ductile behaviour and flexural failure with a deflection ductility index of 4. FE models of HCFPS were developed using the program ABAQUS and validated with experimental results. The governing criteria of stiffness and flexural performance of HCFPS can be improved by enhancing the properties of component materials. HCFPS is 50-70% lighter in weight when compared to conventional floor systems. This study shows that HCFPS can be used for floor structures in commercial and residential buildings as an alternative to conventional steel concrete composite systems.

Effect of the sterilization method on the properties of Bombyx mori silk fibroin films

We have compared the effects of different sterilization techniques on the properties of Bombyx mori silk fibroin thin films with the view to subsequent use for corneal tissue engineering. The transparency, tensile properties, corneal epithelial cell attachment and degradation of the films were used to evaluate the suitability of certain sterilization techniques including gamma-irradiation (in air or nitrogen), steam treatment and immersion in aqueous ethanol. The investigations showed that gamma-irradiation, performed either in air or in a nitrogen atmosphere, did not significantly alter the properties of films. The films sterilized by gamma-irradiation or by immersion in ethanol had a transparency greater than 98% and tensile properties comparable to human cornea and amniotic membrane, the materials of choice in the reconstruction of ocular surface. Although steam-sterilization produced stronger, stiffer films, they were less transparent, and cell attachment was affected by the variable topography of these films. It was concluded that gamma-irradiation should be considered to be the most suitable method for the sterilization of silk fibroin films, however, the treatment with ethanol is also an acceptable method.

Regulating for corporate human rights abuses : the emergence of corporate reporting on the ILO’s human rights standards within the global garment manufacturing and retail industry

Despite the ubiquitous nature of the discourse on human rights there is currently little research on the emergence of disclosure by multinational corporations on their human rights obligations or the regulatory dynamic that may lie behind this trend. In an attempt to begin to explore the extent to which, if any, the language of human rights has entered the discourse of corporate accountability, this paper investigates the adoption of the International Labour Organisation's (ILO) human rights standards by major multinational garment retail companies that source products from developing countries, as disclosed through their reporting media. The paper has three objectives. Firstly, to empirically explore the extent to which a group of multinational garment retailers invoke the language of human rights when disclosing their corporate responsibilities. The paper reviews corporate reporting media including social responsibility codes of conduct, annual reports and stand-alone social responsibility reports released by 18 major global clothing and retail companies during a period from 1990 to 2007. We find that the number of companies adopting and disclosing on the ILO's workplace human rights standards has significantly increased since 1998 – the year in which the ILO's standards were endorsed and accepted by the global community (ILO, 1998). Secondly, drawing on a combination of Responsive Regulation theory and neo-institutional theory, we tentatively seek to understand the regulatory space that may have influenced these large corporations to adopt the language of human rights obligations. In particular, we study the role that International Governmental Organisation's (IGO) such as ILO may have played in these disclosures. Finally, we provide some critical reflections on the power and potential within the corporate adoption of the language of human rights.

Paleomagnetic data support Early Permian age for the Abor Volcanics in the lower Siang Valley, NE India; significance for Gondwana-related break-up models

Confusion exists as to the age of the Abor Volcanics of NE India. Some consider the unit to have been emplaced in the Early Permian, others the Early Eocene, a difference of ∼230 million years. The divergence in opinion is significant because fundamentally different models explaining the geotectonic evolution of India depend on the age designation of the unit. Paleomagnetic data reported here from several exposures in the type locality of the formation in the lower Siang Valley indicate that steep dipping primary magnetizations (mean = 72.7 ± 6.2°, equating to a paleo-latitude of 58.1°) are recorded in the formation. These are only consistent with the unit being of Permian age, possibly Artinskian based on a magnetostratigraphic argument. Plate tectonic models for this time consistently show the NE corner of the sub-continent >50°S; in the Early Eocene it was just north of the equator, which would have resulted in the unit recording shallow directions. The mean declination is counter-clockwise rotated by ∼94°, around half of which can be related to the motion of the Indian block; the remainder is likely due local Himalayan-age thrusting in the Eastern Syntaxis. Several workers have correlated the Abor Volcanics with broadly coeval mafic volcanic suites in Oman, NE Pakistan–NW India and southern Tibet–Nepal, which developed in response to the Cimmerian block peeling-off eastern Gondwana in the Early-Middle Permian, but we believe there are problems with this model. Instead, we suggest that the Abor basalts relate to India–Antarctica/India–Australia extension that was happening at about the same time. Such an explanation best accommodates the relevant stratigraphical and structural data (present-day position within the Himalayan thrust stack), as well as the plate tectonic model for Permian eastern Gondwana.

The cultivation of human retinal pigment epithelial cells on Bombyx mori silk fibroin

We have presently evaluated membranes prepared from Bombyx mori silk fibroin (BMSF), for their potential use as a prosthetic Bruch’s membrane and carrier substrate for human retinal pigment epithelial (RPE) cell transplantation. Porous BMSF membranes measuring 3 μm in thickness were prepared from aqueous solutions (3% w/v) containing poly(ethylene oxide) (0.09%). The permeability coefficient for membranes was between 3 and 9 × 10-5 cm/s by using Allura red or 70 kDa FITC-dextran respectively. Average pore size (± sd) was 4.9 ± 2.3 µm and 2.9 ± 1.5 µm for upper and lower membrane surfaces respectively. Optimal attachment of ARPE-19 cells to BMSF membrane was achieved by pre-coating with vitronectin (1 µg/mL). ARPE-19 cultures maintained in low serum on BMSF membranes for approximately 8 weeks, developed a cobble-stoned morphology accompanied by a cortical distribution of F-actin and ZO-1. Similar results were obtained using primary cultures of human RPE cells, but cultures took noticeably longer to establish on BMSF compared with tissue culture plastic. These findings encourage further studies of BMSF as a substrate for RPE cell transplantation.

Optimisation of bio-oil extraction process from Beauty Leaf (Calophyllum inophyllum) oil seed as a second generation biodiesel source

The Beauty Leaf tree (Calophyllum inophyllum) is a potential source of non-edible vegetable oil for producing future generation biodiesel because of its ability to grow in a wide range of climate conditions, easy cultivation, high fruit production rate, and the high oil content in the seed. This plant naturally occurs in the coastal areas of Queensland and the Northern Territory in Australia, and is also widespread in south-east Asia, India and Sri Lanka. Although Beauty Leaf is traditionally used as a source of timber and orientation plant, its potential as a source of second generation biodiesel is yet to be exploited. In this study, the extraction process from the Beauty Leaf oil seed has been optimised in terms of seed preparation, moisture content and oil extraction methods. The two methods that have been considered to extract oil from the seed kernel are mechanical oil extraction using an electric powered screw press, and chemical oil extraction using n-hexane as an oil solvent. The study found that seed preparation has a significant impact on oil yields, especially in the screw press extraction method. Kernels prepared to 15% moisture content provided the highest oil yields for both extraction methods. Mechanical extraction using the screw press can produce oil from correctly prepared product at a low cost, however overall this method is ineffective with relatively low oil yields. Chemical extraction was found to be a very effective method for oil extraction for its consistence performance and high oil yield, but cost of production was relatively higher due to the high cost of solvent. However, a solvent recycle system can be implemented to reduce the production cost of Beauty Leaf biodiesel. The findings of this study are expected to serve as the basis from which industrial scale biodiesel production from Beauty Leaf can be made.

Raman spectroscopic study of the hydroxy-phosphate mineral plumbogummite PbAl3(PO4)2(OH,H2O)6

Plumbogummite PbAl3(PO4)2(OH,H2O)6 is a mineral of environmental significance and is a member of the alunite-jarosite supergroup. The molecular structure of the mineral has been investigated by Raman spectroscopy. The spectra of different plumbogummite specimens differ although there are many common features. The Raman spectra prove the spectral profile consisting of overlapping bands and shoulders. Raman bands and shoulders observed at 971, 980, 1002 and 1023 cm−1 (China sample) and 913, 981, 996 and 1026 cm−1 (Czech sample) are assigned to the ν1 symmetric stretching modes of the (PO4)3−, at 1002 and 1023 cm−1 (China) and 996 and 1026 cm−1 to the ν1 symmetric stretching vibrations of the (O3POH)2− units, and those at 1057, 1106 and 1182 (China) and at 1102, 1104 and 1179 cm−1 (Czech) to the ν3 (PO4)3− and ν3 (PO3) antisymmetric stretching vibrations. Raman bands and shoulders at 634, 613 and 579 cm−1 (China) and 611 and 596 cm−1 (Czech) are attributed to the ν4 (δ) (PO4)3− bending vibrations and those at 507, 494 and 464 cm−1 (China) and 505 and 464 cm−1 (Czech) to the ν2 (δ) (PO4)3− bending vibrations. The Raman spectrum of the OH stretching region is complex. Raman bands and shoulders are identified at 2824, 3121, 3249, 3372, 3479 and 3602 cm−1 for plumbogummite from China, and at 3077, 3227, 3362, 3480, 3518 and 3601 cm−1 for the Czech Republic sample. These bands are assigned to the ν OH stretching modes of water molecules and hydrogen ions. Approximate O–H⋯O hydrogen bond lengths inferred from the Raman spectra vary in the range >3.2–2.62 Å (China) and >3.2–2.67 Å (Czech). The minority presence of some carbonate ions in the plumbogummite (China sample) is connected with distinctive intensity increasing of the Raman band at 1106 cm−1, in which may participate the ν1 (CO3)2− symmetric stretching vibration overlapped with phosphate stretching vibrations.

Characterising nutrients wash-off for effective urban stormwater treatment design

This paper characterises nitrogen and phosphorus wash-off processes on urban road surfaces to create fundamental knowledge to strengthen stormwater treatment design. The study outcomes confirmed that the composition of initially available nutrients in terms of their physical association with solids and chemical speciation determines the wash-off characteristics. Nitrogen and phosphorus wash-off processes are independent of land use, but there are notable differences. Nitrogen wash-off is a “source limiting” process while phosphorus wash-off is “transport limiting”. Additionally, a clear separation between nitrogen and phosphorus wash-off processes based on dissolved and particulate forms confirmed that the common approach of replicating nutrients wash-off based on solids wash-off could lead to misleading outcomes particularly in the case of nitrogen. Nitrogen is present primarily in dissolved and organic form and readily removed even by low intensity rainfall events, which is an important consideration for nitrogen removal targeted treatment design. In the case of phosphorus, phosphate constitutes the primary species in wash-off for the particle size fraction <75 µm, while other species are predominant in particle size range >75 µm. This means that phosphorus removal targeted treatment design should consider both phosphorus speciation as well as particle size.

Vibrational spectroscopy of the borate mineral henmilite Ca2Cu[B(OH)4]2(OH)4

Henmilite is a triclinic mineral with the crystal structure consisting of isolated B(OH)4 tetrahedra, planar Cu(OH)4 groups and Ca(OH)3 polyhedra. The structure can also be viewed as having dimers of Ca polyhedra connected to each other through 2B(OH) tetrahedra to form chains parallel to the C axis. The structure of the mineral has been assessed by the combination of Raman and infrared spectra. Raman bands at 902, 922, 951, and 984 cm−1 and infrared bands at 912, 955 and 998 cm−1 are assigned to stretching vibrations of tetragonal boron. The Raman band at 758 cm−1 is assigned to the symmetric stretching mode of tetrahedral boron. The series of bands in the 400–600 cm−1 region are due to the out-of-plane bending modes of tetrahedral boron. Two very sharp Raman bands are observed at 3559 and 3609 cm−1. Two infrared bands are found at 3558 and 3607 cm−1. These bands are assigned to the OH stretching vibrations of the OH units in henmilite. A series of Raman bands are observed at 3195, 3269, 3328, 3396, 3424 and 3501 cm−1 are assigned to water stretching modes. Infrared spectroscopy also identified water and OH units in the henmilite structure. It is proposed that water is involved in the structure of henmilite. Hydrogen bond distances based upon the OH stretching vibrations using a Libowitzky equation were calculated. The number and variation of water hydrogen bond distances are important for the stability off the mineral.

Vibrational spectroscopy of the borate mineral kotoite Mg3(BO3)2

Vibrational spectroscopy has been used to assess the structure of kotoite a borate mineral of magnesium which is isostructural with jimboite. The mineral is orthorhombic with point group: 2/m 2/m 2/m. The mineral has the potential as a new memory insulator material. The mineral has been characterised by a combination of Raman and infrared spectroscopy. The Raman spectrum is dominated by a very intense band at 835 cm−1, assigned to the symmetric stretching mode of tetrahedral boron. Raman bands at 919, 985 and 1015 cm−1 are attributed to the antisymmetric stretching modes of tetrahedral boron. Kotoite is strictly an hydrous borate mineral. An intense Raman band observed at 3559 cm−1 is attributed to the stretching vibration of hydroxyl units, more likely to be associated with the borate mineral hydroxyborate. The lack of observation of water bending modes proves the absence of water in the kotoite structure.

A vibrational spectroscopic study of philipsbornite PbAl3(AsO4)2(OH)5⋅H2O-molecular structural implications and relationship to the crandallite subgroup arsenates

The presence of arsenic in the environment is a hazard. The accumulation of arsenate by a range of cations in the formation of minerals provides a mechanism for the remediation of arsenate contamination. The formation of the crandallite group of minerals provides a mechanism for arsenate accumulation. Among the crandallite minerals are philipsbornite, arsenocrandallite and arsenogoyazite. Raman spectroscopy complimented with infrared spectroscopy has enabled aspects of the structure of philipsbornite to be studied. The Raman spectrum of philipsbornite displays an intense band at around 840 cm−1 attributed to the overlap of the symmetric and antisymmetric stretching modes. Raman bands observed at 325, 336, 347, 357, 376 and 399 cm−1 are assigned to the ν2 (AsO4)3− symmetric bending vibration (E) and to the ν4 bending vibration (F2). The observation of multiple bending modes supports the concept of a reduction in symmetry of the arsenate anion in philipsbornite. Evidence for phosphate in the mineral is provided. By using an empirical formula, hydrogen bond distances for the OH units in philipsbornite of 2.8648 Å, 2.7864 Å, 2.6896 Å cm−1 and 2.6220 were calculated.

Vibrational spectroscopic characterization of the phosphate mineral ludlamite (Fe,Mn,Mg)3(PO4)2⋅4H2O – a mineral found in lithium bearing pegmatites

The objective of this work is to analyze ludlamite (Fe,Mn,Mg)3(PO4)2⋅4H2O from Boa Vista mine, Galiléia, Brazil and to assess the molecular structure of the mineral. The phosphate mineral ludlamite has been characterized by EMP-WDS, Raman and infrared spectroscopic measurements. The mineral is shown to be a ferrous phosphate with some minor substitution of Mg and Mn. Raman bands at 917 and 950 cm−1 are assigned to the symmetric stretching mode of and units. Raman bands at 548, 564, 599 and 634 cm−1 are assigned to the ν4 bending modes. Raman bands at 2605, 2730, 2896 and 3190 cm−1 and infrared bands at 2623, 2838, 3136 and 3185 cm−1 are attributed to water stretching vibrations. By using a Libowitzky empirical function, hydrogen bond distances are calculated from the OH stretching wavenumbers. Strong hydrogen bonds in the structure of ludlamite are observed as determined by their hydrogen bond distances. The application of infrared and Raman spectroscopy to the study of ludlamite enables the molecular structure of the pegmatite mineral ludlamite to be assessed.

A vibrational spectroscopic study of the phosphate mineral zanazziite - Ca2(MgFe2+)(MgFe2+Al)4Be4(PO4)6⋅6(H2O)

Zanazziite is the magnesium member of a complex beryllium calcium phosphate mineral group named roscherite. The studied samples were collected from the Ponte do Piauí mine, located in Itinga, Minas Gerais. The mineral was studied by electron microprobe, Raman and infrared spectroscopy. The chemical formula can be expressed as Ca2.00(Mg3.15,Fe0.78,Mn0.16,Zn0.01,Al0.26,Ca0.14)Be4.00(PO4)6.09(OH)4.00⋅5.69(H2O) and shows an intermediate member of the zanazziite–greinfeinstenite series, with predominance of zanazziite member. The molecular structure of the mineral zanazziite has been determined using a combination of Raman and infrared spectroscopy. A very intense Raman band at 970 cm−1 is assigned to the phosphate symmetric stretching mode whilst the Raman bands at 1007, 1047, 1064 and 1096 cm−1 are attributed to the phosphate antisymmetric stretching mode. The infrared spectrum is broad and the antisymmetric stretching bands are prominent. Raman bands at 559, 568, 589 cm−1 are assigned to the ν4 out of plane bending modes of the PO4 and HPO4 units. The observation of multiple bands supports the concept that the symmetry of the phosphate unit in the zanazziite structure is reduced in symmetry. Raman bands at 3437 and 3447 cm−1 are attributed to the OH stretching vibrations; Raman bands at 3098 and 3256 are attributed to water stretching vibrations. The width and complexity of the infrared spectral profile in contrast to the well resolved Raman spectra, proves that the pegmatitic phosphates are better studied with Raman spectroscopy.