Type II muscle fibre properties are not associated with balance recovery following large perturbations during walking in young and older adults

Falls among older adults are often attributed to declining muscle strength with ageing. Associations between muscle strength and balance control have been reported, but the evidence for, and key mechanisms of resistance exercise in fall prevention are unclear. No studies have directly examined the relationship between muscle fibre characteristics and reactive balance control. Here, we address whether or not Type II muscle fibre characteristics associate with reactive balance during walking in young and older adults with varying muscle fibre type composition. We analyse muscle biopsy-derived fibre characteristics and stability during a treadmill-based walking perturbation (trip-like) task of healthy young adults, healthy, normally active older adults, trained older adults and physically impaired older adults. We find no significant associations between Type II muscle fibre properties and reactive balance during walking, indicating that practitioners and researchers should consider more than just the muscle tissue properties when assessing and intervening on fall risk.

Bar forces in pulp refiners

Refiners develop pulp properties by applying forces on fibres during bar crossings. The size of these forces is critical in developing fibre properties while avoiding fibre shortening. This study has shown that bar force calculated from Specific Edge load (SEL) gives the same result as vector-based derivations of average bar force. Predicted forces agree reasonably well with ones measured by a novel piezo-electric sensor in refiner bars and forces estimated from measurements of fibre shortening.

Influence of fibre properties and its proportion on filtration behaviour of thermo-bonded multilayer nonwoven

Purpose The purpose of this paper is to study the influence of fibre properties on filtration behavior. Air pollution is a major threat to human beings due to industrialization and urbanization. Among various particles in the atmospheric air, PM 2.5 causes various respiratory problems to human beings and also causes premature engine wear. The primary importance for the filters is higher filtration efficiency with lower pressure drop. Design/methodology/approach In this research, nonwoven filters were developed with different diameters of polyester fibres such as 0.8d, 1.2d and 6d fibres and different proportions of fibres were used. The Kuwabara cell model was used to derive certain parameters and its effects were analysed. The effect of basis length, solid volume fraction and porosity on filtration behavior was discussed in detail. Findings The filtration efficiency is higher for particle size from 1–3 µm, when different layers of polyester fibres are used with coarser fibres as the top layer and finer as the bottom layer. The filtration performance is better for layered nonwoven than unimodal nonwoven. The higher proportion of micro-denier fibres results in higher filtration efficiency with higher pressure drop. Research limitations/implications The proposed research is more suitable for the particle size of more than 1 µm because of the fibre diameters and its achievable porosity. The filtration efficiency can be increased further by increasing the mass per unit area, which also increases the pressure and is not recommended. Originality/value The effect of triple-layers with different diameters of fibres on filtration was analysed. Due to the variation in diameters of fibres in different layers, the filtration performance varies.

Fibre development in an intensified mechanical pulping process

Mechanical pulp for printing paper can be produced with a process that involve much less equipment and that require much lower specific energy compared to conventional processes. Even though common evaluation methods, e.g. handsheet testing, have shown that the pulp quality is similar for the simplified and the conventional processes, it is not known how fibre properties, at the microscopic level, is developed with the simplified process. In this mill scale study, the fibre properties attained with an “intensified” mechanical pulping process, consisting of single stage high consistency double disc refining followed by two stage low consistency refining and no reject treatment was investigated. The simplified process was compared to a process with a reject system. The simplified process rendered fibres with higher degree of fibrillation, higher share of axial splits, lower fibre wall thickness but slightly lower length than the conventional process. The fibrillar fines size distribution of the two processes was different. The conventional process generated more of small fibrillar fines which probably explains the higher tensile index at given density for that process. The results show that it is possible to simplify the production process for mechanical pulp and reduce the specific energy with over 700 kWh/adt.

High-Performance Fibres – A Review of Properties and IR-Spectra

High-performance fibres are fibre materials that exhibit at least one extraordinary property compared to con¬ventional fibre materials. That extraordinary property is frequently related to excellent fibre stability against certain influences such as fire, heat, chemicals or light. Also, a high mechanical strength is often a property of high-performance fibres. Nevertheless, it should be noted that high-performance fibres exhibit certain weak¬nesses in addition to their advantages. This review presents a broad overview of the most important high-per¬formance fibres, with a special emphasis on their chemical structure and related infrared spectra (IR-spectra). The categorization of the fibres according to chemical substance classes was performed to make it easy for the reader to find a fibre of interest. The main categories are polyethylene (PE) fibres, polyacrylonitrile (PAN) fibres, polyvinylalcohol (PVAL) fibres, polyester-based fibres, polyamide-based fibres, polyetheretherketone (PEEK) fibres, polyimide (PI) fibres, halogen-containing fibres, polyphenylene sulfide (PPS fibres), resin-based fibres and finally inorganic fibres. Competing materials are also discussed, and structural related materials can be easily identified. In addition to discussing fibre properties and selected applications, one of the main aims is to present a various number of IR-spectra as a tool for structural understanding and to help identify unknown fibres. Here, beside the IR-spectra of high-performance fibres, the reference IR-spectra of common fibres are presented for comparison.

DEVELOPMENT OF WOOD GRINDING 2. EFFECTS OF WOOD MOISTURE ON FIBRE PROPERTIES

"The wood grinding model recently published was based on an energy balance of the active grinding zone, i.e. the limited volumes of wood and grindstone that were heated by the grindstone generated compression and tension strains in the wood surface. Generally speaking, the data obtained in well controlled laboratory grindings complied with the derived model meaning that compression–tension power ratios presented as a function of the specific pulp production resulted in linears. However, the wood moisture contents varying from water-saturated to air-dried wood needed further elaboration for better understanding. Accordingly, the aim of this presentation was to find reasonable explanations for the grinding effects on the wood fibres by considering groundwood pulp and paper sheet properties, for example shives and fines contents, as well as tensile strength and light scattering of the paper sheet. The compression–tension power ratios provided by the model reflect simultaneously both compression and tension strain in wood, and accordingly, the resulting fibre properties would be dependent on both brittle and tough fractures. Evidently, the water contents played a role in this context, both as a stiffener of the water-saturated wood, and as a wood and fibre coolant. "