McGill University

About: McGill University is a education organization based out in Montreal, Quebec, Canada. It is known for research contribution in the topics: Population & Context (language use). The organization has 72688 authors who have published 162565 publications receiving 6966523 citations. The organization is also known as: Royal institution of advanced learning & University of McGill College.

Tough adhesives for diverse wet surfaces

Abstract: Adhesion to wet and dynamic surfaces, including biological tissues, is important in many fields but has proven to be extremely challenging. Existing adhesives are cytotoxic, adhere weakly to tissues, or cannot be used in wet environments. We report a bioinspired design for adhesives consisting of two layers: an adhesive surface and a dissipative matrix. The former adheres to the substrate by electrostatic interactions, covalent bonds, and physical interpenetration. The latter amplifies energy dissipation through hysteresis. The two layers synergistically lead to higher adhesion energies on wet surfaces as compared with those of existing adhesives. Adhesion occurs within minutes, independent of blood exposure and compatible with in vivo dynamic movements. This family of adhesives may be useful in many areas of application, including tissue adhesives, wound dressings, and tissue repair.

Photomobile polymer materials: towards light-driven plastic motors.

Abstract: As light is a good energy source that can be controlled remotely, instantly, and precisely, light-driven soft actuators could play an important role for novel applications in wideranging industrial and medical fields. Liquid-crystalline elastomers (LCEs) are unique materials having both properties of liquid crystals (LCs) and elastomers, and a large deformation can be generated in LCEs, such as reversible contraction and expansion, and even bending, by incorporating photochromic molecules, such as an azobenzene, with the aid of photochemical reactions of these chromophores. Herein we demonstrate new sophisticated motions of LCEs and their composite materials: a plastic motor driven only by light. If materials absorb light and change their shape or volume, they can convert light energy directly into mechanical work (the photomechanical effect) and could be very efficient as a single-step energy conversion. Furthermore, these photomobile materials would be widely applicable because they can be controlled remotely just by manipulating the irradiation conditions. LCEs show an anisotropic order of mesogens with a cooperative effect, which leads them to undergo an anisotropic contraction along the alignment direction of mesogens when heated above their LC-isotropic(I) phase transition temperatures (TLC-I) and an expansion by lowering the temperature below TLC-I. [1, 13–18] The expansion and contraction is due to the microscopic change in alignment of mesogens, followed by the significant macroscopic change in order through the cooperative movement of mesogens and polymer segments. It is well known that when azobenzene derivatives are incorporated into LCs, the LC-I phase transition can be induced isothermally by irradiation with UV light to cause trans–cis photoisomerization, and the I-LC reverse-phase transition by irradiation with visible light to cause cis–trans back-isomerization. This photoinduced phase transition (or photoinduced reduction of LC order) has led successfully to a reversible deformation of LCEs containing azobenzene chromophores just by changing the wavelength of actinic light. Although the photoinduced deformation of LCEs previously reported is large and interesting, it is limited to contraction/expansion and bending, preventing them from being used for actual applications. Herein we report potentially applicable rotational motions of azobenzene-containing LCEs and their composite materials, including a first lightdriven plastic motor with laminated films composed of an LCE film and a flexible polyethylene (PE) sheet. The LCE films were prepared by photopolymerization of a mixture of an LC monomer containing an azobenzene moiety (molecule 1 shown in Scheme 1) and an LC diacrylate with an azobenzene moiety (2 in Scheme 1) with a ratio of 20/ 80 mol/mol, containing 2 mol% of a photoinitiator in a glass cell coated with rubbed polyimide alignment layers. The photopolymerization was conducted at a temperature at which the mixture exhibited a smectic phase. The glasstransition temperature of the LCE films is at about room temperature, allowing the LCE films to work at room temperature in air, as the films are flexible enough at this temperature. We prepared a continuous ring of the LCE film by connecting both ends of the film. The azobenzene mesogens were aligned along the circular direction of the ring. Upon exposure to UV light from the downside right and visible light from the upside right simultaneously (Figure 1), the ring

Combining individual interviews and focus groups to enhance data richness

Abstract: Title. Combining individual interviews and focus groups to enhance data richness. Aim. This paper is a presentation of the critical reflection on the types of findings obtained from the combination of individual interviews and focus groups, and how such triangulation contributes to knowledge production and synthesis. Background. Increasingly, qualitative method triangulation is advocated as a strategy to achieve more comprehensive understandings of phenomena. Although ontological and epistemological issues pertaining to triangulation are a topic of debate, more practical discussions are needed on its potential contributions, such as enhanced data richness and depth of inquiry. Method. Data gathered through individual interviews and focus groups from a study on patterns of cancer information-seeking behaviour are used to exemplify the added-value but also the challenges of relying on methods combination. Findings. The integration of focus group and individual interview data made three main contributions: a productive iterative process whereby an initial model of the phenomenon guided the exploration of individual accounts and successive individual data further enriched the conceptualisation of the phenomenon; identification of the individual and contextual circumstances surrounding the phenomenon, which added to the interpretation of the structure of the phenomenon; and convergence of the central characteristics of the phenomenon across focus groups and individual interviews, which enhanced trustworthiness of findings. Conclusion. Although the use of triangulation is promising, more work is needed to identify the added-value or various outcomes pertaining to method combination and data integration.

Cyclic administration of pamidronate in children with severe osteogenesis imperfecta.

Abstract: Background Severe osteogenesis imperfecta is a disorder characterized by osteopenia, frequent fractures, progressive deformity, loss of mobility, and chronic bone pain. There is no effective therapy for the disorder. We assessed the effects of treatment with a bisphosphonate on bone resorption. Methods In an uncontrolled observational study involving 30 children who were 3 to 16 years old and had severe osteogenesis imperfecta, we administered pamidronate intravenously (mean [±SD] dose, 6.8±1.1 mg per kilogram of body weight per year) at 4-to-6-month intervals for 1.3 to 5.0 years. Clinical status, biochemical characteristics reflecting bone turnover, the bone mineral density of the lumbar spine, and radiologic changes were assessed regularly during treatment. Results Administration of pamidronate resulted in sustained reductions in serum alkaline phosphatase concentrations and in the urinary excretion of calcium and type I collagen N-telopeptide. There was a mean annualized increase of 41.9±29.0 percent ...