Chondrocyte redifferentiation and construct mechanical property development in single-component photocrosslinkable hydrogels

Hydrogels are promising materials for cartilage repair, but the properties required for optimal functional outcomes are not yet known. In this study, we functionalized four materials that are commonly used in cartilage tissue engineering and evaluated them using in vitro cultures. Gelatin, hyaluronic acid, polyethylene glycol, and alginate were functionalized with methacrylic anhydride to make them photocrosslinkable. We found that the responses of encapsulated human chondrocytes were highly dependent on hydrogel type. Gelatin hydrogels supported cell proliferation and the deposition of a glycosaminoglycan rich matrix with significant mechanical functionality. However, cells had a dedifferentiated phenotype, with high expression of collagen type I. Chondrocytes showed the best redifferentiation in hyaluronic acid hydrogels, but the newly formed matrix was highly localized to the pericellular regions, and these gels degraded rapidly. Polyethylene glycol hydrogels, as a bioinert control, did not promote any strong responses. Alginate hydrogels did not support the deposition of new matrix, and the stiffness decreased during culture. The markedly different response of chondrocytes to these four photocrosslinkable hydrogels demonstrates the importance of material properties for chondrogenesis and extracellular matrix production, which are critical for effective cartilage repair.

Cathodic corrosion of Cu substrates as a route to nanostructured Cu/M (M = Ag, Au, Pd) surfaces

The electrochemical formation of nanostructured materials is generally achieved by reduction of a metal salt onto a substrate that does not influence the composition of the deposit. In this work we report that Ag, Au and Pd electrodeposited onto Cu under conditions where galvanic replacement is not viable and hydrogen gas is evolved results in the formation of nanostructured surfaces that unexpectedly incorporate a high concentration of Cu in the final material. Under cathodic polarization conditions the electrodissolution/corrosion of Cu occurs which provides a source of ionic copper that is reduced at the surface-electrolyte interface. The nanostructured Cu/M (M = Ag, Au and Pd) surfaces are investigated for their catalytic activity for the reduction of 4 nitrophenol by NaBH4 where Cu/Ag was found to be extremely active. This work indicates that a substrate electrode can be utilized in an interesting manner t make bimetallic nanostructures with enhanced catalytic activity.

Activation of the canonical Wnt signaling pathway induces cementum regeneration

Canonical Wnt signaling is important in tooth development but it is unclear whether it can induce cementogenesis and promote the regeneration of periodontal tissues lost due to disease. Therefore, the aim of this study is to investigate the influence of canonical Wnt signaling enhancers on human periodontal ligament cell (hPDLCs) cementogenic differentiation in vitro and cementum repair in a rat periodontal defect model. Canonical Wnt signaling was induced by (i) local injection of lithium chloride; (ii) local injection of sclerostin antibody; and (iii) local injection of a lentiviral construct overexpressing β-catenin. The results showed that the local activation of canonical Wnt signaling resulted in significant new cellular cementum deposition and the formation of well-organized periodontal ligament fibers, which was absent in the control group. In vitro experiments using hPDLCs showed that the Wnt signaling pathway activators significantly increased mineralization, alkaline phosphatase (ALP) activity, and gene and protein expression of the bone and cementum markers osteocalcin (OCN), osteopontin (OPN), cementum protein 1 (CEMP1), and cementum attachment protein (CAP). Our results show that the activation of the canonical Wnt signaling pathway can induce in vivo cementum regeneration and in vitro cementogenic differentiation of hPDLCs.

Project-based civil engineering courses

Problem solving is an essential element of civil engineering education. It has been observed that students are best able to understand civil engineering theory when there is a practical application of it. Teaching theory alone has led to lower levels of comprehension and motivation and a correspondingly higher rate of failure and “drop-out”. This paper analyses the effectiveness of introducing practical design projects at an early stage within a civil engineering undergraduate program at Queensland University of Technology. In two of the essential basic subjects, Engineering Mechanics and Steel Structures, model projects which simulate realistic engineering exercises were introduced. Students were required to work in small groups to analyse, design and build the lightest / most efficient model bridges made of specific materials such as spaghetti, drinking straw, paddle pop sticks and balsa wood and steel columns for a given design loading/target capacity. The paper traces the success of the teaching strategy at each stage from its introduction through to the final student and staff evaluation.

Towards coordinated multirobot missions for lunar sample collection in an unknown environment

In this paper, the recent results of the space project IMPERA are presented. The goal of IMPERA is the development of a multirobot planning and plan execution architecture with a focus on a lunar sample collection scenario in an unknown environment. We describe the implementation and verification of different modules that are integrated into a distributed system architecture. The modules include a mission planning approach for a multirobot system and modules for task and skill execution within a lunar use-case scenario. The skills needed for the test scenario include cooperative exploration and mapping strategies for an unknown environment, the localization and classification of sample containers using a novel approach of semantic perception, and the skill of transporting sample containers to a collection point using a mobile manipulation robot. Additionally, we present our approach of a reliable communication framework that can deal with communication loss during the mission. Several modules are tested within several experiments in the domain of planning and plan execution, communication, coordinated exploration, perception, and object transportation. An overall system integration is tested on a mission scenario experiment using three robots.

Indicator Bats Program: A System for the Global Acoustic Monitoring of Bats

Bats are an important component of mammalian biodiversity and fill such a wide array of ecological niches that they may offer an important multisensory bioindicator role in assessing ecosystem health. There is a need to monitor population trends of bats for their own sake because many populations face numerous environmental threats related to climate change, habitat loss, fragmentation, hunting, and emerging diseases. To be able to establish bat ultrasonic biodiversity trends as a reliable indicator, it is important to standardize monitoring protocols, data management, and analyses. This chapter discusses the main issues to be considered in developing a bat ultrasonic indicator. It focuses on the results from indicator bats program (iBats), a system for the global acoustic monitoring of bats, in Eastern Europe. Finally, the chapter reviews the strengths and weaknesses of the Program and considers the opportunities and threats that it may face in the future.

Inhaled corticosteroids for sub-acute cough in children (Protocol)

This is the protocol for a review and there is no abstract. The objectives are as follows: To evaluate the efficacy of inhaled corticosteroids in reducing the severity of cough in children with sub-acute cough (defined as cough duration of two to four weeks).

Microparticle-mediated gene delivery for the enhanced expression of a 19-KDa fragment of merozoite surface protein 1 of Plasmodium falciparum

The 19 kDa carboxyl-terminal fragment of merozoite surface protein 1 (MSP119) is a major component of the invasion-inhibitory response in individual immunity to malaria. A novel ultrasonic atomization approach for the formulation of biodegradable poly(lactic-co-glycolic acid) (PLGA) microparticles of malaria DNA vaccines encoding MSP119 is presented here. After condensing the plasmid DNA (pDNA) molecules with a cationic polymer polyethylenimine (PEI), a 40 kHz ultrasonic atomization frequency was used to formulate PLGA microparticles at a flow rate of 18 mL h1. High levels of gene expression and moderate cytotoxicity in COS-7 cells were achieved with the condensed pDNA at a nitrogen to phosphate (N/P) ratio of 20, thus demonstrating enhanced cellular uptake and expression of the transgene. The ability of the microparticles to convey pDNA was examined by characterizing the formulated microparticles. The microparticles displayed Z-average hydrodynamic diameters of 1.50-2.10 lm and zeta potentials of 17.8-23.2 mV. The encapsulation efficiencies were between 78 and 83%, and 76 and 85% of the embedded malaria pDNA molecules were released under physiological conditions in vitro. These results indicate that PLGA-mediated microparticles can be employed as potential gene delivery systems to antigen-presenting cells in the prevention of malaria.