CD73 and CD29 concurrently mediate the mechanically induced decrease of migratory capacity of mesenchymal stromal cells

The assumption that mesenchymal stromal cell (MSC)-based therapies are capable of augmenting physiological regeneration processes has fostered intensive basic and clinical research activities. However, to achieve sustained therapeutic success in vivo, not only the biological, but also the mechanical microenvironment of MSCs during these regeneration processes needs to be taken into account. This is especially important for e.g., bone fracture repair, since MSCs present at the fracture site undergo significant biomechanical stimulation. This study has therefore investigated cellular characteristics and the functional behaviour of MSCs in response to mechanical loading. Our results demonstrated a reduced expression of MSC surface markers CD73 (ecto-5’-nucleotidase) and CD29 (integrin β1) after loading. On the functional level, loading led to a reduced migration of MSCs. Both effects persisted for a week after the removal of the loading stimulus. Specifi c inhibition of CD73/CD29 demonstrated their substrate dependent involvement in MSC migration after loading. These results were supported by scanning electron microscopy images and phalloidin staining of actin fi laments displaying less cell spreading, lamellipodia formation and actin accumulations. Moreover, focal adhesion kinase and Src-family kinases were identified as candidate downstream targets of CD73/CD29 that might contribute to the mechanically induced decrease in MSC migration. These results suggest that MSC migration is controlled by CD73 CD29, which in turn are regulated by mechanical stimulation of cells. We therefore speculate that MSCs migrate into the fracture site, become mechanically entrapped, and thereby accumulate to fulfil their regenerative functions.

Seismic capacity of building constructed in slip formed load bearing wall panels

Constructing buildings using slip formed load bearing wall panels is becoming increasingly popular in Sri Lanka due to several advantages; low cost, environmental friendliness and rapid construction technique. These wall panels are already successfully implemented in many low rise buildings. However, the seismic capacities of these buildings have not been properly studied. Few seismic activities reported in Sri Lanka have not caused severe structural damage, but predictions can not be made as to whether this will continue to be the case in the future. This highlights the need to study the seismic capacity of buildings constructed in slip formed load bearing wall panels. This paper presents a study of the seismic capacity of the existing medium rise building.

Greener and leaner : unleashing capacity of railroad concrete ties via limit states concept

New knowledge has raised a concern about the cost-ineffective design methods and the true performance of railroad prestressed concrete ties. Because of previous knowledge deficiencies, railway civil and track engineers have been aware of the conservative design methods for structural components in any railway track that rely on allowable stresses and material strength reductions. In particular, railway sleeper (or railroad tie) is an important component of railway tracks and is commonly made of prestressed concrete. The existing code for designing such components makes use of the permissible stress design concept, whereas the fiber stresses over cross sections at initial and final stages are limited by some empirical values. It is believed that the concrete ties complying with the permissible stress concept possess unduly untapped fracture toughness, based on a number of proven experiments and field data. Collaborative research run by the Australian Cooperative Research Centre for Railway Engineering and Technologies (Rail CRC) was initiated to ascertain the reserved capacity of Australian railway prestressed concrete ties that were designed using the existing design code. The findings have led to the development of a new limit-states design concept. This paper highlights the conventional and the new limit-states design philosophies and their implication to both the railway community and the public. © 2011 American Society of Civil Engineers.

Ergodic capacity of the exponentially correlated slotted amplify and forward relay channel

In this paper we analyze the performance degradation of slotted amplify-and-forward protocol in wireless environments with high node density where the number of relays grows asymptotically large. Channel gains between source-destination pairs in such networks can no longer be independent. We analyze the degradation of performance in such wireless environments where channel gains are exponentially correlated by looking at the capacity per channel use. Theoretical results for eigenvalue distribution and the capacity are derived and compared with the simulation results. Both analytical and simulated results show that the capacity given by the asymptotic mutual information decreases with the network density.

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.

Teaching Teachers for the Future (TTF) : building the ICT in education capacity of the next generation of teachers in Australia

The Teaching Teachers for the Future (TTF) project is a unique nationally significant project funded by the Australian Government through the Department of Employment, Education and Workplace Relations (DEEWR, Au$8.8 million) and the Information and Communication Technology Innovation Fund (ICTIF). This 2011-2012 project has ambitiously attempted to build the ICT education (ICTE) capacity of the next generation of Australian teachers through its focus on pre-service teachers, teacher educators and the new Australian Curriculum. This paper will provide an overview of the project including a description of its genesis in a changing educational and political landscape, its structure and operations, its grounding in contemporary theory, the research opportunities it has engendered and its tangible outcomes.

Preparation, characterization and in vitro angiogenic capacity of cobalt substituted β-tricalcium phosphate ceramics

Divalent cobalt ions (Co2+) have been shown to possess the capacity to induce angiogenesis by activating hypoxia inducible factor-1α (HIF-1α) and subsequently inducing the production of vascular endothelial growth factor (VEGF). However, there are few reports about Co-containing biomaterials for inducing in vitro angiogenesis. The aim of the present work was to prepare Co-containing β-tricalcium phosphate (Co-TCP) ceramics with different contents of calcium substituted by cobalt (0, 2, 5 mol%) and to investigate the effect of Co substitution on their physicochemical and biological properties. Co-TCP powders were synthesized by a chemistry precipitation method and Co-TCP ceramics were prepared by sintering the powder compacts. The effect of Co substitution on phase transition and the sintering property of the β-TCP ceramics was investigated. The proliferation and VEGF expression of human bone marrow mesenchymal stem cells (HBMSCs) cultured with both powder extracts and ceramic discs of Co-TCP was further evaluated. The in vitro angiogenesis was evaluated by the tube-like structure formation of human umbilical vein endothelial cells (HUVECs) cultured on ECMatrix™ in the presence of powder extracts. The results showed that Co substitution suppressed the phase transition from β- to α-TCP. Both the powder extracts and ceramic discs of Co-TCP had generally good cytocompatibility to support HBMSC growth. Importantly, the incorporation of Co into β-TCP greatly stimulated VEGF expression of HBMSCs and Co-TCP showed a significant enhancement of network structure formation of HUVECs compared with pure TCP. Our results suggested that the incorporation of Co into bioceramics is a potential viable way to enhance angiogenic properties of biomaterials. Co-TCP bioceramics may be used for bone tissue regeneration with improved angiogenic capacity.

Ergodic capacity of the slotted amplify and forward relay channel with finite relays

Abstract—In this paper we investigate the capacity of a general class of the slotted amplify and forward (SAF) relaying protocol where multiple, though a finite number of relays may transmit in a given cooperative slot and the relay terminals being half-duplex have a finite slot memory capacity. We derive an expression for the capacity per channel use of this generalized SAF channel assuming all source to relay, relay to destination and source to destination channel gains are independent and modeled as complex Gaussian. We show through the analysis of eigenvalue distributions that the increase in limiting capacity per channel use is marginal with the increase of relay terminals.

High resolution imaging of boron carbide microstructures

Two samples of boron carbide have been examined using high resolution transmission electron microscopy (HRTEM). A hot pressed B13C2 sample shows a high density of variable width twins normal to (10-11). Subtle shifts or offsets of lattice fringes along the twin plane and normal to (10 5) were also observed. A B4C powder showed little evidence of stacking disorder in crystalline regions.

Analytical electron microscope investigation of boron carbide microstructures at elevated temperatures

The microstructures of hot-pressed B4C were monitored during in situ heating experiments from room temperature to 1000C by analytical electron microscopy (AEM). Variations in the microstructure of B4C were not observed. However, during heating, secondary phases formed in voids and on the surfaces of the specimen.

A bound on the maximum strong order of stochastic Runge-Kutta methods for stochastic ordinary differential equations

In Burrage and Burrage [1] it was shown that by introducing a very general formulation for stochastic Runge-Kutta methods, the previous strong order barrier of order one could be broken without having to use higher derivative terms. In particular, methods of strong order 1.5 were developed in which a Stratonovich integral of order one and one of order two were present in the formulation. In this present paper, general order results are proven about the maximum attainable strong order of these stochastic Runge-Kutta methods (SRKs) in terms of the order of the Stratonovich integrals appearing in the Runge-Kutta formulation. In particular, it will be shown that if an s-stage SRK contains Stratonovich integrals up to order p then the strong order of the SRK cannot exceed min{(p + 1)/2, (s - 1)/2), p greater than or equal to 2, s greater than or equal to 3 or 1 if p = 1.

Preparation and thermal energy storage properties of paraffin/calcined diatomite composites as form-stable phase change materials

A composite paraffin-based phase change material (PCM) was prepared by blending composite paraffin and calcined diatomite through the fusion adsorption method. In this study, raw diatomite was purified by thermal treatment in order to improve the adsorption capacity of diatomite, which acted as a carrier material to prepare shape-stabilized PCMs. Two forms of paraffin (paraffin waxes and liquid paraffin) with different melting points were blended together by the fusion method, and the optimum mixed proportion with a suitable phase-transition temperature was obtained through differential scanning calorimetry (DSC) analysis. Then the prepared composite paraffin was adsorbed in calcined diatomite. The prepared paraffin/calcined diatomite composites were characterized by the scanning electron microscope (SEM) and Fourier transformation infrared (FT-IR) analysis techniques. Thermal energy storage properties of the composite PCMs were determined by DSC method. DSC results showed that there was an optimum adsorption ratio between composite paraffin and calcined diatomite and the phase-transition temperature and the latent heat of the composite PCMs were 33.04 ◦C and 89.54 J/g, respectively. Thermal cycling test of composite PCMs showed that the prepared material is thermally reliable and chemically stable. The obtained paraffin/calcined diatomite composites have proper latent heat and melting temperatures, and show practical significance and good potential application value.

Application of profluorescent nitroxides for measurements of oxidative capacity of combustion generated particles

Oxidative stress caused by generation of free radicals and related reactive oxygen species (ROS) at the sites of deposition has been proposed as a mechanism for many of the adverse health outcomes associated with exposure to particulate matter (PM). Recently, a new profluorescent nitroxide molecular probe (BPEAnit) developed at QUT was applied in an entirely novel, rapid and non-cell based assay for assessing the oxidative potential of particles (i.e. potential of particles to induce oxidative stress). The technique was applied on particles produced by several combustion sources, namely cigarette smoke, diesel exhaust and wood smoke. One of the main findings from the initial studies undertaken at QUT was that the oxidative potential per PM mass significantly varies for different combustion sources as well as the type of fuel used and combustion conditions. However, possibly the most important finding from our studies was that there was a strong correlation between the organic fraction of particles and the oxidative potential measured by the PFN assay, which clearly highlights the importance of organic species in particle-induced toxicity.