337 research outputs found
Measurement of collagen synthesis by cells grown under different mechanical stimuli
INTRODUCTION: The use of scaffolds in tissue engineering is essential to provide cells with a matrix for cell proliferation and differentiation resulting in tissue regeneration. Normally this process involves seeding cells onto an artificial biodegradable scaffold providing mechanical support for cells until there is sufficient extracellular matrix deposition (ECM) to replace the artificial scaffold. Collagen is the bulk protein found in the ECM and measurement of its synthesis is the most direct, absolute indicator of ECM production
Nanofibers-based piezoelectric energy harvester for self-powered wearable technologies
The demands for wearable technologies continue to grow and novel approaches for powering these devices are being enabled by the advent of new energy materials and novel manufacturing strategies. In addition, decreasing the energy consumption of portable electronic devices has created a huge demand for the development of cost-effective and environment friendly alternate energy sources. Energy harvesting materials including piezoelectric polymer with its special properties make this demand possible. Herein, we develop a flexible and lightweight nanogenerator package based on polyvinyledene fluoride (PVDF)/LiCl electrospun nanofibers. The piezoelectric performance of the developed nanogenator is investigated to evaluate effect of the thickness of the as-spun mat on the output voltage using a vibration and impact test. It is found that the output voltage increases from 1.3 V to 5 V by adding LiCl as additive into the spinning solution compared with pure PVDF. The prepared PVDF/LiCl nanogenerator is able to generate voltage and current output of 3 V and 0.5 ”A with a power density output of 0.3 ”W cmâ2 at the frequency of 200 Hz. It is found also that the developed nanogenerator can be utilized as a sensor to measure temperature changes from 30âŠC to 90âŠC under static pressure. The developed electrospun temperature sensor showed sensitivity of 0.16%/âŠC under 100 Pa pressure and 0.06%/âŠC under 220 Pa pressure. The obtained results suggested the developed energy harvesting textiles have promising applications for various wearable self-powered electrical devices and systems
International tourists' spending on traveling inside a destination : does local happiness matter?
This paper investigates the travel spending behaviour of international tourists inside happier destinations. The empirical model is tested for 58 developed and developing countries. Applying various estimation methods and two different measures of nationsâ happiness, the results show that tourists spend more on travelling inside a destination where local people are happier. In addition, we find that foreign touristsâ expenditures on travelling are higher in countries with a higher quality of travel infrastructure and larger numbers of World Heritage sites. Our results provide some implications for tourism planners and authorities
Dynamic mechanical and creep behaviour of meltspun pvdf nanocomposite fibers
Piezoelectric fibers have an important role in wearable technology as energy generators and sensors. A series of hybrid nanocomposite piezoelectric fibers of polyinylidene fluoride (PVDF) loaded with bariumâtitanium oxide (BT) and reduced graphene oxide (rGO) were prepared via the melt spinning method. Our previous studies show that high-performance fibers with 84% of the electroactive ÎČ-phase in the PVDF generated a peak output voltage up to 1.3 V and a power density of 3 W kgâ1. Herein, the dynamic mechanical and creep behavior of these fibers were investigated to evaluate their durability and piezoelectric performance. Dynamic mechanical analysis (DMA) was used to provide phenomenological information regarding the viscoelastic properties of the fibers in the longitudinal direction. DSC and SEM were employed to characterize the crystalline structure of the samples. The storage modulus and the loss tangent increased by increasing the frequency over the temperature range (â50 to 150 °C) for all of the fibers. The storage modulus of the PVDF/rGO nanocomposite fibers had a higher value (7.5 GPa) in comparison with other fibers. The creep and creep recovery behavior of the PVDF/nanofillers in the nanocomposite fibers have been explored in the linear viscoelastic region at three different temperatures (10â130 °C). In the PVDF/rGO nanocomposite fibers, strong sheet/matrix interfacial interaction restricted the mobility of the polymer chains, which led to a higher modulus at temperatures 60 and 130 °C
Tactile sensors for robot handling
First and second generation robots have been used cost effectively in highâvolume âfixedâ or âhardâ automated manufacturing/assembly systems. They are âlimitedâabilityâ devices using simple logic elements or primitive sensory feedback. However, in the unstructured environment of most manufacturing plants it is often necessary to locate, identify, orientate and position randomly presented components.
Visual systems have been researched and developed to provide a coarse resolution outline of objects. More detailed and precise definition of parts is usually obtained by high resolution tactile sensing arrays. This paper reviews and discusses the current state of the art in tactile sensing
The impact of board and hotel characteristics on biodiversity reporting: Market diversification as a moderator
Purpose: This study aims to explain how board and hotel characteristics affect biodiversity reporting and to test the moderating effect of market diversification. Design/methodology/approach: The annual reports of 105 hotels were examined for the period between 2016 and 2017 to analyse these hotelsâ biodiversity reporting using content analysis. The partial least squares technique was used to test the proposed relationships. Findings: The results show that the number of board members who are also on the corporate social responsibility committee, number of board members who are in environmental organizations, the star rating of the hotel, hotel size and hotel location have significant positive effects on the extent of biodiversity reporting. In addition, market diversification moderates positively the effects of number of board members with environmental experience and number of board members from environmental organizations on the extent of biodiversity reporting. Practical implications: The results of this study will be useful in enabling hotel manager and investors to become knowledgeable about these aspects of boards, which lead to higher biodiversity reporting. This study can also inform policymakers about the types of hotels that are less likely to disclose biodiversity reports and to develop effective enforcement of regulations. Originality/value: These findings extend the literature on biodiversity reporting by exploring the importance of board and hotel characteristics on the extent of biodiversity reporting and testing the moderating effect of market diversification
THE EFFECT OF PROGRESSIVE RESISTANCE TRAINING ON BIOMECHANICS OF ARTHRITIC GAIT: A SINGLE-BLIND RANDOMIZED CONTROL TRIAL
INTRODUCTION: Osteoarthritis (OA) is prevalent in elderly and is associated with muscle weakness. OA progression is related to biomechanical characteristics of gait such as knee adduction moment (KAM). Progressive resistance training (PRT) improves muscle strength in this population, but PRT effects on biomechanics of gait related to OA progression are unknown. We hypothesized that PRT would reduce KAM, mediated by improvements in the strength of all lower limb muscle groups
THE EFFECT OF PROGRESSIVE RESISTANCE TRAINING ON BIOMECHANICS OF ARTHRITIC GAIT: A SINGLE-BLIND RANDOMIZED CONTROL TRIAL
INTRODUCTION: Osteoarthritis (OA) is prevalent in elderly and is associated with muscle weakness. OA progression is related to biomechanical characteristics of gait such as knee adduction moment (KAM). Progressive resistance training (PRT) improves muscle strength in this population, but PRT effects on biomechanics of gait related to OA progression are unknown. We hypothesized that PRT would reduce KAM, mediated by improvements in the strength of all lower limb muscle groups
- âŠ