Enhancement of the dielectric permittivity and magnetic properties of Dy substituted strontium titanate ceramics

Structural, dielectric and magnetic properties of dense Dy-substituted strontium titanate ceramics are investigated. In the Sr_1-1.5xDy_xTiO₃ system, incorporation of Dy onto the Sr site is confirmed by a linear decrease of the lattice parameter up to x = 0.05. Dielectric spectroscopy analysis of Sr_1-1.5xDy_xTiO₃ ceramics reveals four relaxations. Two relaxations observed below 55 K are attributed to dipoles formed by off-centre displacement of Dy³⁺ ions on the Sr sites. Other two dielectric relaxations found at higher temperatures are attributed to the oxygen vacancy related mechanisms. As result, very high dielectric permittivity of ～33500 at 28 K and of ～9600 around room temperature at moderate dissipation factor of ～0.02 are obtained for Sr_0.985Dy_0.01TiO₃ ceramics, making it a promising material for capacitor electronic applications. Paramagnetic behaviour observed for Sr_1-1.5xDy_xTiO₃ as well as for Sr_1-xDy_2xTi_1-xO₃ ceramics indicates impossibility to induce a magnetic order and hence magnetoelectric coupling in strontium titanate by Dy substitution.     

Influence of Process Conditions on the Mass Transfer Kinetics of Pulsed Vacuum Osmotically Dehydrated Mango Slices

The pulsed vacuum osmotic dehydration of mango slices was studied using a 2^5–1 fractional factorial design. The process responses were water loss, solids gain, water activity, and the effective diffusivities of the water or solids. Statistical analyses revealed that temperature and solution concentration were significant for all the responses studied. Vacuum time was significant for solids gain and the effective diffusivity of water. Diffusion coefficients were determined using an analytical solution of Fick's unidirectional diffusion equation for flat plates, showing a good fit to the experimental data. Osmotic recirculation and vacuum pressure had no effect on any of the responses studied.     

How to Stop Engineers from Becoming “Bush Lawyers”: The Art of Teaching Law to Engineering and Construction Students

Law forms a core part of most engineering and construction programs. The way that law subjects are taught varies dramatically, and too often focuses on trying to teach students complex aspects of the law, such as contract, tort, and trade practices. This paper suggests that the aim of including law subjects in construction and engineering degrees needs to be clearly understood as this determines the content of the law subject. It is argued that the reason for including a law subject should be not to teach students the law, but rather to train them to recognize when legal issues arise in their work, and how to respond to such issues. With this aim in mind, a model curriculum is proposed and insight given into how to most effectively implement such a course.     

Highly porous and interconnected starch-based scaffolds: Production,characterization and surface modification

A convenient and straightforward process for preparation of highly porous and interconnected fiber mesh scaffolds with 50 wt.% content of starch is described. The proposed methodology avoids some of the previous encountered problems associated with the processing of starch-based materials such as thermal degradation, starch entrapment in the material bulk and inability to control/minimise the thickness of the fibers obtained by melt spinning, or low porosity and lack of interconnectivity for the scaffolds obtained by extrusion or injection moulding with blowing agent. Topographical characterisation of the obtained fibers revealed rough surface commonly related with increased cell attachment and growth. The in vitro tests with osteoblast cell line confirmed this trend and we observed higher cell number with increasing of the culture time. These results were also associated with protein adsorption from a complex solution where predominant adsorption of vitronectin over fibronectin was detected. Finally, a model modification by plasma was also carried out in order to confirm the versatility of these scaffolds by the possibility to further upgrade them via surface functionalisation. The in vitro tests confirmed that osteoblast-like cells proliferate faster on the modified scaffolds, which allows shortening the time needed for culturing prior to implantation.     

Proteins and proteolysis in pre-term and term human milk and possible implications for infant formulae

Understanding the differences between the protein system of human milk and bovine milk is critical in the development of infant formulae. In this study, the proteins of bovine milk and a bovine-based whey-dominant infant formula were compared with those of human milk for infants born prematurely (pre-term) or at full term (term). The protein distribution of infant formula differed significantly from that of either type of human milk. A proteomic comparison between pre-term and term human milk showed a reduction of levels of β-casein and α_s-casein and appearance of additional products, corresponding to low molecular weight hydrolysis products of the caseins, in pre-term milk. Pre-term milk samples also had higher total nitrogen concentration and plasmin activity, consistent with the proteomic data. These results suggest the operation of a physiological mechanism that may adjust enzyme and/or protein expression to modify protein digestibility, and may facilitate design of infant formulae, closer to maternal milk, particularly for premature infants.     

Interpersonal predictors of depression trajectories in women with HIV.

This article tests an interpersonal model of depression symptom trajectories tailored to the experiences of women with HIV. Specifically, the authors examined how bereavement, maternal role difficulty, HIV-related social isolation, and partner conflict predicted change in depressive symptoms over 5 years in 761 women with HIV, controlling for sociodemographic and clinical health factors. Of these interpersonal characteristics, partner conflict emerged as a robust predictor of change in depressive symptoms in growth curve and cross-lag models. Results highlight the need for interventions focusing on interpersonal issues, particularly intimate relationships, in women with HIV. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Solar air conditioning and its role in alleviating the energy crisis of the Mediterranean hotels

The Intergovernmental Panel on Climate Change has estimated that the Mediterranean region could experience an increase in annual mean temperatures up to 7.1°C by the end of the century. Within the same time frame, the fossil fuel stocks are predicted to diminish, resulting in ever increasing fuel prices. Furthermore, there is continuous political pressure to impose greenhouse gas levies and quotas for industries and services alike, thus adding into their operational expenditures should they exceed their carbon quotas. The hotel industry, in particular, is predicted to suffer from the direct and indirect effects of climate change and increasing fuel prices. Not only are their operating costs bound to increase but in addition, they may suffer from reduced tourist flows if and when the airline industry is forced to increase travel prices. It is in this context of a predicted ‘energy crisis’ within the hotel industry that this study was undertaken in order to evaluate the extent to which hotels can future-proof their operations.

Integration of renewable energy sources into hotel operations is perceived as the most promising form of crisis mitigation. In the Mediterranean region, the availability of solar irradiation is abundant and free from microclimatic limitations associated with wind energy in comparison. Therefore, solar-assisted air conditioning was identified as a key strategy because its operational principal dictates that the greatest availability of energy coincides with the peak demands.

The aim of this article is to review the currently available solar air-conditioning technologies, their energy saving potential and technical limitations. The study is based on a literature review supplemented with information available from equipment vendors. Subsequently, the objective of this article is to set solar air-conditioning equipment selection criteria that could assist hotels of various service classes in their energy planning and equipment upgrades.     

The meaning of molluscs: Leonce Reynaud and the Cuvier-Geoffroy Debate of 1830, Paris

In Paris, in 1830, a fierce debate broke out in the Academie Royale des Sciences between zoologists Georges Cuvier and Etienne Geoffroy Saint-Hilaire over the anatomy of molluscs. At the same time, a heated controversy arose in the Academie des Beaux-Arts between Quatremere de Quincy and Henri Labrouste over the morphology of built form. Among Labrouste's supporters was architect Leonce Reynaud who, along with his brother Jean Reynaud, a prominent editor and philosopher, also supported Geoffroy's side in the debate. These men saw the slow growth of the mollusc as a metaphor for human history, and they viewed its malleable body as a model for social reform. The architectural challenge was to accept the lower classes as the very future of urban society. In Paris, even as the July Revolution of 1830 raised the political stakes once again, this was the meaning of molluscs.     

Preparation and Characterization of the Novels Terpolymers of Poly-{trans-[RuCl2(vpy)4]-styrene-divinylbenzene} and Styrene-divinylbenzene-vinylpiridine impregnated with Silver Nanoparticles

This paper reports the preparation and characterization of poly-{trans-[RuCl₂(vpy)₄-styrene-divinylbenzene} and styrene-divinylbenzene-vinylpiridine filled with nanosilver. Theses materials were synthesized by non aqueous polymerization through a chemical reaction using benzoyl peroxide as the initiator. The nanosilver was obtained from chemical reduction using NaBH₄ as reducing agent and sodium citrate as stabilizer. The nanometric dimension of nanosilver was monitored by UV-visible and confirmed through TEM. The morphology was characterized by SEM and the thermal properties were done by TGA and DSC. The antimicrobial action of the polymers impregnated with nanosilver was evaluated using both microorganisms, Staphylococcus aureus and Escherichia coli. The antimicrobial activity of the poly-{trans-[RuCl₂(vpy)₄]-styrene-divinylbenzene} filled with nanosilver was confirmed by the presence of an inhibition halo of the bacterial growth in seeded culture media, but was not confirmed to the styrene-divinylbenzene-vinylpiridine. The present work suggest that trans - [RuCl₂(vpy)₄] complex facilitate the release of silver ion from the media.