Skeletal muscle fiber construction for tissue-engineered grafts requires assembly of unidirectionally aligned juxtaposed myotubes. To construct such a tissue, a polymer microchip with linearly aligned microgrooves was fabricated that could direct myoblast adaptation under stringent conditions. The closely spaced microgrooves fabricated by a modified replica molding process guided linear cellular alignment. Examination of the myoblasts by immunofluorescence microscopy demonstrated that the microgrooves with subcellular widths and appropriate height-to-width ratios were required for practically complete linear alignment of myoblasts. The topology-dependent cell alignment encouraged differentiation of myoblasts into multinucleate, myosin heavy chain positive myotubes. The monolayer of myotubes formed on the microstructured chips allowed attachment, growth and differentiation of subsequent layers of linearly arranged myoblasts, parallel to the primary monolayer of myotubes. The consequent deposition of additional myoblasts on the previous layer of myotubes resulted in three-dimensional multi-layered structures of myotubes, typical of differentiated skeletal muscle tissue. The findings demonstrate that the on-chip device holds promise for providing an efficient means for guided muscle tissue construction.

Doping effect of diamond nanoparticles on the superconducting properties of MgB 2 bulk material has been studied. It is found that the superconducting transition temperature T c of MgB 2 is suppressed by the diamond-doping, however, the irreversibility field H irr and the critical current density J c are systematically enhanced. Microstructural analysis shows that the diamond-doped MgB 2 superconductor consists of tightly-packed MgB 2 nano-grains (~50-100 nm) with highly-dispersed and uniformly-distributed diamond nanoparticles (~10-20 nm) inside the grains. High density of dislocations and diamond nanoparticles may take the responsibility for the enhanced flux pinning in the diamond-doped MgB 2 . *Corresponding author: email: c.cheng@unsw.edu.au 2 I IntroductionSince the discovery of superconductivity at 39 K in MgB 2 [1], significant progress has been made in improving the performance of MgB 2 materials [2][3][4][5][6][7]. MgB 2 offers the possibility of wide engineering applications in the temperature range 20-30 K, where conventional superconductors, such as Nb 3 Sn and Nb-Ti alloy, cannot play any roles due to their low T c .However, the realization of large-scale applications for MgB 2 -based superconductivity technology essentially relies on the improvement of the pinning behaviour of MgB 2 in high fields. As it has poor grain connection and a lack of pinning centres, MgB 2 often exhibits a rapid decrease in critical current density, J c , in high magnetic fields. Fortunately, through the formation of nanoparticle structures in bulk MgB 2 [3][4][5] and thin films [7], the problem of the poor grain connection can be solved, and the flux pinning force can also be significantly enhanced due to an increase of pinning centres served by grain boundaries. In order to improve further the performance of MgB 2 , it is necessary to introduce more pinning centres, especially those consisting of nano-sized second-phase inclusions which often provide strong pinning forces.Nano-diamond, prepared by the detonation technique, has been widely used as an additive to improve the performance of various materials [8]. However, nano-diamond-doping effect on the superconducting properties MgB 2 has never been reported although carbon with other forms has been used as dopants in MgB 2 [9][10][11]. The high dispersibility of the nanodiamond powder makes it possible to form a high density of nano-inclusions in MgB 2 matrix.In this article, we have investigated the doping effect of nano-diamond on the superconducting properties of MgB 2 . Our results show that the nano-diamond-doped MgB 2 consists of tightly-packed MgB 2 nano-grains (~50-100 nm) with diamond nanoparticles (~10-20 nm) wrapped within the grains. This unique microstructure provides the samples with a good grain connection for the MgB 2 phase and a high density of flux-pinning centres served 3 by the diamond nanoparticles. Compared to the MgB 2 bulk materials doped with other nanoparticles [3][4][5][6][7], the irreversibility line has been significantly improved and ...

Recognition of body posture and motion is an important physiological function that can keep the body in balance. Man-made motion sensors have also been widely applied for a broad array of biomedical applications including diagnosis of balance disorders and evaluation of energy expenditure. This paper reviews the state-of-the-art sensing components utilized for body motion measurement. The anatomy and working principles of a natural body motion sensor, the human vestibular system, are first described. Various man-made inertial sensors are then elaborated based on their distinctive sensing mechanisms. In particular, both the conventional solid-state motion sensors and the emerging non solid-state motion sensors are depicted. With their lower cost and increased intelligence, man-made motion sensors are expected to play an increasingly important role in biomedical systems for basic research as well as clinical diagnostics.

MgB 2 -diamond nanocomposite superconductors have been synthesized by addition of nano-diamond powder. Microstructural analysis shows that the nanocomposite superconductor consists of tightly-packed MgB 2 nano-grains (~50-100 nm) with highlydispersed and uniformly-distributed diamond nanoparticles (~10-20 nm) inside the grains. However, the realization of large-scale applications for MgB 2 -based superconductivity technology essentially relies on the improvement of the pinning behaviour of MgB 2 in high fields. As it has poor grain connection and a lack of pinning centres, MgB 2 often exhibits a rapid decrease in critical current density, J c , in high magnetic fields. Fortunately, through the formation of nanoparticle structures in bulk MgB 2 [2-4] and thin films [5], the problem of the poor grain connection can be solved, and the flux pinning force can also be significantly enhanced due to an increase of pinning centres served by grain boundaries. In order to improve further the performance of MgB 2 , it is necessary to introduce more pinning centres, especially those consisting of nano-sized second-phase inclusions, which often provide strong pinning forces.Nano-diamond, prepared by the detonation technique, has been widely used as an additive to improve the performance of various materials [6]. Yet, nano-diamond has never been used to increase the flux pinning force in MgB 2 superconductors until the present study.The high dispersibility of the nano-diamond powder makes it possible to form a high density of nano-inclusions in MgB 2 matrix. In this letter, we have successfully prepared the MgB 2 -diamond nanocomposite, which consists of tightly-packed MgB 2 nano-grains (~50-100 nm)with diamond nanoparticles (~10-20 nm) wrapped within the grains. This unique microstructure provides the composite with a good grain connection for the MgB 2 phase and a high density of flux-pinning centres served by the diamond nanoparticles. Compared to the MgB 2 bulk materials prepared with other techniques, the irreversibility line has been significantly improved and the J c in high magnetic fields has been largely increased in the MgB 2 -diamond nanocomposite.The MgB 2 -diamond nanocomposites with compositions of MgB 2-x C x (x=0, 5%, 8%, and 10%) were prepared by solid-state reaction at ambient pressure. Mg powder (99% purity, 325 meshes), amorphous B powder (99% purity, submicron-size), and nano-diamond powder (10-20 nm) were mixed and ground in air for 1 h. An extra 2% of Mg powder was added in the starting materials to compensate the loss of Mg caused by high temperature evaporation.The mixed powders were pressed into pellets with dimensions of 20x10x3 mm 3 under a pressure of 800 kg/cm 2 , sandwiched into two MgO plates, sintered in flowing Ar at 800 o C for 2 h, and then quenched to room-temperature in air. In order to compare the substitution effect of carbon in boron in MgB 2 with the additional effect of the nano-diamond in MgB 2 , a sample with an added 1.5 wt% of nano-diamond in MgB 2 was prepared. The sintering tem...