Simulations of the Behaviour of Steel Ferromagnetic Fibres Commonly Used in Concrete in a Magnetic Field

The efficiency of fibre reinforcement in concrete can be drastically increased by orienting the fibres using a magnetic field. This orientation occurs immediately after pouring fresh concrete when the fibres can still move. The technique is most relevant for manufacturing prefabricated elements such as beams or columns. However, the parameters of such a field are not immediately apparent, as they depend on the specific fibre reaction to the magnetic field. In this study, a numerical model was created in ANSYS Maxwell to examine the mechanical torque acting on fibres placed in a magnetic field with varying parameters. The model consists of a single fibre placed between two Helmholtz coils. The simulations were verified with an experimental setup as well as theoretical relationships. Ten different fibre types, both straight and hook-ended, were examined. The developed model can be successfully used to study the behaviour of fibres in a magnetic field. The fibre size plays the most important role together with the magnetic saturation of the fibre material. Multiple fibres show significant interactions.

Supercritical Carbon Dioxide Isolation of Cellulose Nanofibre and Enhancement Properties in Biopolymer Composites

The physical properties, such as the fibre dimension and crystallinity, of cellulose nanofibre (CNF) are significant to its functional reinforcement ability in composites. This study used supercritical carbon dioxide as a fibre bundle defibrillation pretreatment for the isolation of CNF from bamboo, in order to enhance its physical properties. The isolated CNF was characterised through zeta potential, TEM, XRD, and FT-IR analysis. Commercial CNF was used as a reference to evaluate the effectiveness of the method. The physical, mechanical, thermal, and wettability properties of the bamboo and commercial CNF-reinforced PLA/chitin were also analysed. The TEM and FT-IR results showed the successful isolation of CNF from bamboo using this method, with good colloidal stability shown by the zeta potential results. The properties of the isolated bamboo CNF were similar to the commercial type. However, the fibre diameter distribution and the crystallinity index significantly differed between the bamboo and the commercial CNF. The bamboo CNF had a smaller fibre size and a higher crystallinity index than the commercial CNF. The results from the CNF-reinforced biocomposite showed that the physical, mechanical, thermal, and wettability properties were significantly different due to the variations in their fibre sizes and crystallinity indices. The properties of bamboo CNF biocomposites were significantly better than those of commercial CNF biocomposites. This indicates that the physical properties (fibre size and crystallinity) of an isolated CNF significantly affect its reinforcement ability in biocomposites. The physical properties of isolated CNFs are partly dependent on their source and production method, among other factors. These composites can be used for various industrial applications, including packaging.

Application of Taguchi Robust Design for optimizing tensile strength response of Ukam-plant fibre reinforced cashew nut shell liquid (CNSL) composite by the effects of control parameters

This paper focuses on the application of Taguchi Robust Design to determine the optimum tensile strength of Ukam-Plant Fibre Reinforced CNSL Composite using indigenous or locally sourced vegetable or plant based natural fibres (Ukam-plant fibres) that are Lignocellulose as potential raw material. Tensile tests were conducted on the replicated samples of Ukam-Plant Fibre Reinforced CNSL Composite to obtain the optimum properties. Hounsfield Mosanto Tensometer, a universal testing machine was used to conduct tensile tests to determine the control factor levels quality characteristics considered necessary to optimize the mechanical property being investigated. Methodology of traditional and experimental design approach of Taguchi was used for the larger the better to obtain the highest signal to noise ratio (SN ratio) for the quality characteristic being investigated and also to correlate the control factors (fibre condition i.e. untreated, silane treated and alkaline treated, volume fraction and fibre size). Minitab 16 software was used for statistical analysis to fine-tune conclusions and produce quantitative estimates. The optimum settings were as follows: alkaline treatment, volume fraction of 50%, and 50mm of fibre size which resulted in 18.69MPa optimum tensile strength. The experimental results obtained agreed satisfactorily with the Minitab 16 software predictions. The mechanical property studied revealed that composite depends significantly on the reinforcement combination of control parameters.

Tensile Properties of Natural Fibre Reinforced Polymer Composite Foams: A Systematic Review

Biodegradable foam packaging was chosen as an alternative food packaging material due to non-toxic and produced from renewable sources. Researchers has turned to incorporate natural fibre to enhance the mechanical properties of polymer composite foam. In this study, the objective is to identify the studies which investigated on the tensile properties of natural fiber incorporated polymer composite foam and analyzed the effect of natural fibre content and size on tensile properties. Further correlation between the natural fibre content and size on tensile properties of composite polymer foam was conducted. The studies on the natural fibre incorporated polymer composite was identify via PRISMA method. The effect of natural fibre content and natural fibre size on tensile properties of polymer composite foam were analyzed in terms of qualitative analysis via systematic review. This study employs systematic review method on the existing literature. This study has utilized supplementary databases such as SAGE Journals, ScienceDirect, Taylor & Francis, Emerald Insight, ERIC ProQuest, SpringerLink and IEEE Xplore to cater all the possible relevant literature for a comprehensive review. The systematic review method comprised of the steps that explain on the review process in the sequence of the (identification, screening, eligibility), data analysis and data abstraction. From the article used in this systematic review, most of the result shown the increased tensile properties on natural fibre reinforced polymer composite foams. The study by Texteira et al. (2014) shows that the softwood fibre with 33% of PLA loading has the highest elongation at break, and highest natural fibre size (2470 µm). While the study by Long et al. (2019) has the highest tensile strength with 30% of ABF fibre content. The composition of 20 wt% BF with 80 wt% PLA composites were concluded to have the optimum tensile properties

Older adults are not more susceptible to acute muscle atrophy after immobilisation compared to younger adults: a systematic review

Purpose To identify if older adults are more susceptible to acute muscle atrophy compared to younger adults. Methods All studies whose design involved a period of enforced immobilisation and a comparison between an older (> 40) and a younger cohort (< 40) were included. Outcome of interest was change in muscle mass, measured by radiological techniques or histological analysis of fibre size. Medline, Embase and Cochrane databases were systematically searched and records screened by two independent reviewers. Studies selected for inclusion were critically appraised and individually assessed for risk of bias. GRADE framework guided the assessment of quality of studies. Results Eight articles were included (193 participants). 14 (7.3%) were female and 102 (52.8%) were in older groups. Mean age for older adults was 66.3 years and for younger adults 23.3 years. Immobilisation periods spanned 4–14 days as simulated by bed rest, limb brace or limb cast. Studies measured muscle mass by DXA, CT, MRI or fibre cross-sectional area, or a combination of each. Muscles studied included quadriceps, adductor pollicis, vastus lateralis or combined lean leg mass. Of the radiological measures, three studies (74 participants) reported greater atrophy in the older group, three studies (76 participants) reported greater atrophy in the younger group. Reduction in muscle mass varied in older adults between 0.19 and 0.76% per day, and for younger adults between 0.06 and 0.70% per day. Due to substantial heterogeneity, a meta-analysis was not performed. Five studies reported fibre size. Change in fibre size varied considerably between each study, with no convincing overall trend for either older or younger groups. Conclusion The current literature suggests that there is no difference in the rate of muscle atrophy after immobilisation in older people compared to younger people, and therefore that older people are not more susceptible to atrophy in the acute setting. However, the findings are inconsistent and provide statistically significant but opposing results. There is a lack of high-quality research available on the topic, and there is a paucity of literature regarding atrophy rates in women.

Generation of Core–Sheath Polymer Nanofibers by Pressurised Gyration

The ability to generate core–sheath bicomponent polymer nanofibers in a single-step with scale-up possibilities is demonstrated using pressurised gyration manufacturing. This is the first time that nanofiber containing more than one polymer having a core–sheath configuration has been generated in this way. Water-soluble polymers polyethylene oxide (PEO) and polyvinyl pyrrolidone (PVP) are used as the core and sheath layers, respectively. Core–sheath nanofibers with a diameter in the range of 331 to 998 nm were spun using 15 wt % PEO and 15 wt % PVP polymer solutions. The forming parameters, working pressure and rotating speed, had a significant influence on the size, size distribution and the surface morphology of the nanofibers generated. Overall, fibre size decreased with increasing working pressure and rotating speed. The fibre size was normally distributed in all cases, with 0.2 MPa working pressure in particular showing narrower distribution. The fibre size distributions for 0.1 and 0.3 MPa working pressure were broader and a mean fibre size of 331 nm was obtained in the latter case. The fibre size was evenly distributed and narrower for rotating speeds of 2000 and 4000 RPMs. The distribution was broader for rotating speed of 6000 RPM with a mean value obtained at 430 nm. Continuous, smooth and bead-free fibre morphologies were obtained in each case. The fibre cross-section analysis using a focused ion beam machine showed a solid core surrounded by a sheath layer. Our findings demonstrate that the pressurised gyration could be used to produce core–sheath polymer nanofibers reliably and cost-effectively with scale-up possibilities (~4 kg h−1).

Strength training as a supplemental therapy for androgen deficiency of the aging male (ADAM): study protocol for a three-arm clinical trial

IntroductionAndrogen deficiency of the ageing male is a clinical syndrome resulting from the low production of androgens (testosterone levels <6.9 nmol/L) with symptoms including decline in lean mass, muscle strength, increases in body mass and overall fat mass. The aim of the study is to examine the effect of a 12 week strength training intervention on body composition, physical function, muscle cellular and molecular and selected biochemical markers of metabolic health in hypogonadal patients.Methods and analysisThe study is three-group controlled 12-week experiment to assess the effect of strength training on hypogonadal patients with testosterone replacement therapy and newly diagnosed males without testosterone replacement therapy. Age matched healthy eugonadal males are also engaged in strength training. Lean mass is used to determine sample size indicating, that 22 subjects per group will be sufficient to detect intervention related changes at the power of 0.90. All outcomes are collected before the intervention (pre-intervention assessments) and after the intervention (post-intervention assessments). Clinical outcomes are body composition (lean mass, fat mass and total body mass) measured by dual-energy X-ray absorptiometry, physical functioning assessed by physical tests and psychosocial functioning. The most important haematological and biochemical parameters included are glucose, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, testosterone, luteinizing hormone, follicle-stimulating hormone, sexhormone-binding globulin, insulin and prostate-specific antigen. Muscle cellular and molecular outcomes are muscle fibre size and regulators of muscle fibre size. Muscle cellular outcomes are measured from muscle biopsies obtained from musculus vastus lateralis.Ethics and disseminationThis trial is approved by Ethics Committee of the University Hospital in Bratislava, Slovakia, (ref. trial number: 127/2017) and all subjects will be fully informed on the rationale, risks and benefits of the study and sign the written informed consent prior to entering the study. Results will be published in peer-reviewed journals and presented in scientific conferences.Trial registration numberNCT03282682