Search results for "strength"
showing 10 items of 2415 documents
Characterization of Food Packaging Films with Blackcurrant Fruit Waste as a Source of Antioxidant and Color Sensing Intelligent Material
2021
Chitosan and pectin films were enriched with blackcurrant pomace powder (10 and 20% (w/w)), as bio-based material, to minimize food production losses and to increase the functional properties of produced films aimed at food coatings and wrappers. Water vapor permeability of active films increased up to 25%, moisture content for 27% in pectin-based ones, but water solubility was not significantly modified. Mechanical properties (tensile strength, elongation at break and Young’s modulus) were mainly decreased due to the residual insoluble particles present in blackcurrant waste. FTIR analysis showed no significant changes between the film samples. The degradation temperatures, determined by D…
New Polylactic Acid Composites Reinforced with Artichoke Fibers
2015
In this work, artichoke fibers were used for the first time to prepare poly(lactic acid) (PLA)-based biocomposites. In particular, two PLA/artichoke composites with the same fiber loading (10% w/w) were prepared by the film-stacking method: the first one (UNID) reinforced with unidirectional long artichoke fibers, the second one (RANDOM) reinforced by randomly-oriented long artichoke fibers. Both composites were mechanically characterized in tensile mode by quasi-static and dynamic mechanical tests. The morphology of the fracture surfaces was analyzed through scanning electron microscopy (SEM). Moreover, a theoretical model, i.e., Hill's method, was used to fit the experimental Young's modu…
Strength of cellulosic fiber/starch acetate composites with variable fiber and plasticizer content
2014
In this experimental study, the performance of injection-molded short flax and hemp fibers in plasticized starch acetate were analyzed in terms of strength. Parameters involved in the analysis are a variable fiber and plasticizer content. The measured strength of the composites varies in the range of 12–51 MPa for flax fibers and 11–42 MPa for hemp fibers, which is significantly higher than the properties of the unreinforced starch acetate matrix. The micro-structural parameters used in modeling of composite strength were obtained from optical observations and indirect measurements. Some of these parameters were qualitatively verified by X-ray microtomography.
Creep Behavior of Poly(lactic acid) Based Biocomposites
2017
Polymer composites containing natural fibers are receiving growing attention as possible alternatives for composites containing synthetic fibers. The use of biodegradable matrices obtained from renewable sources in replacement for synthetic ones is also increasing. However, only limited information is available about the creep behavior of the obtained composites. In this work, the tensile creep behavior of PLA based composites, containing flax and jute twill weave woven fabrics, produced through compression molding, was investigated. Tensile creep tests were performed at different temperatures (i.e., 40 and 60 °C). The results showed that the creep behavior of the composites is strongly inf…
Protein transport through gold-coated, charged nanopores: Effects of applied voltage
2006
The flux of bovine serum albumin and bovine hemoglobin through charged nanopores inside polymeric membranes is analysed as a function of the applied voltage to the nanopore surface, the solution ionic strength and pH. The electrostatic interaction of the protein with the nanopore surface gives low transport rates except at the protein isoelectric point and the minimum of the effective, voltage-induced nanopore charge. This electrostatic sieving effect allows for the separation of proteins with similar molecular weights.
Densité et mobilité des poissons sous la glace, sur une zone de pêche à la senne de deux lacs finlandais, par écho-intégration.
2000
The density and movements of fish under ice were studied with single-beam mobile surveys and fixed location split-beam surveys, as well as exploratory fishing in winter-seining areas of two shallow Finnish lakes during winter 1999. Fish schooled near the bottom during the day but the schools dispersed and fish ascended at night. Single and split-beam target strength distributions corresponded fairly closely with the length distribution of seine catch samples. Estimated fish densities were greater at night than in daylight. The swimming speed of smelt (Osmerus eperlanus) was 0.18 m·s -1 in daylight and 0.36 m·s -1 at night. The corresponding figures for vendace (Coregonus albula) were 0.11-0…
In vitro control of adventitious bud differentiation by inorganic media components in leaves of matureJuniperus oxycedrus
1995
The effects of changes in the concentration of macronutrients on BA-induced caulogenesis from leaves of matureJuniperus oxycedrus cultured on modified Murashige and Skoog or Schenk and Hildebrandt media are reported. The bud-forming capacity of the explants depended mainly on the ratios among the levels of ammonium, nitrate, and potassium. The most favorable media formulations for differentiation of adventitious buds were those with nitrate:potassium, ammonium:potassium, and nitrate:ammonium ratios near 1, around 0.1, and between 9 and 15, respectively. The total ionic strength of the media limited bud induction, but only when a disequilibrium of these ratios was produced.
Life-history constraints and warning signal expression in an arctiid moth
2007
Summary 1 Traditionally, large pattern elements in conspicuous warning signals are assumed to be selected by predation because increasing signal strength enhances education and avoidance of predators. However, variation in the colour pattern of a warningly coloured species often exists even within a location, and many warning signals have relatively small pattern elements. This suggests that there must be opposing selection pressures that can constrain warning signal expression, resulting in variation in warning signals as well as suboptimal signals for predator education. 2 We quantified the variation in the warning signal of Parasemia plantaginis-moth larvae. With a full-sib rearing exper…
Effects of 24 weeks of single session combined strength and endurance training on body composition and fitness : examination of order effect
2013
Küüsmaa, Maria 2013. Effects of 24 weeks of single session combined strength and endurance training on body composition and fitness: examination of order effect. Department of Biology of Physical Activity, University of Jyväskylä. Master’s Thesis in Science of Sport Coaching and Fitness Testing. 82 pp. Endurance and strength training are often performed concurrently. The question of whether the order of exercise yields to different adaptations in body composition, when strength (S) and endurance training (E) are combined into the same training session, has received only limited scientific attention. In addition, neuromuscular and cardiorespiratory adaptations to single session combined trai…
Effect of Combining Impact-Aerobic and Strength Exercise, and Dietary Habits on Body Composition in Breast Cancer Survivors Treated with Aromatase In…
2023
This study examines both the effect of a twice-weekly combined exercise—1 h session of strength and 1 h session of impact-aerobic—on body composition and dietary habits after one year of treatment with aromatase inhibitors (AI) in breast cancer survivors. Overall, forty-three postmenopausal women with a BMI ≤ 35 kg/m2, breast cancer survivors treated with AI, were randomized into two groups: a control group (CG) (n = 22) and a training group (IG) (n = 21). Body composition, i.e., abdominal, visceral, and subcutaneous adipose tissue) was measured by magnetic resonance. In addition, some questionnaires were used to gather dietary data and to measure adherence to the Mediterranean diet. After …