Search results for "Plastic"
showing 10 items of 7296 documents
Northward invasion of the parasitic deer ked ( Lipoptena cervi), is there geographical variation in pupal size and development duration?
2010
SUMMARYThe deer ked (Lipoptena cervi) is a common ectoparasite of cervids. During the last decades the species has rapidly invaded in northern Europe, especially in Finland, towards the north and increased its prevalence on the moose population. Consequently, during this rapid invasion the deer ked has faced more severe climatic conditions. We studied whether pupal size (measured as pupal weight) and pupal development duration of the deer ked varies along historical invasion zones and temperature zones towards north in Finland. Moreover, we explored possible size- and gender-dependent variation in pupal development duration. We divided wild-collected pupae in respect to their origin in two …
Rays hamper intrusive growth of vessel elements
2021
Key message In some circumstances vessel elements, both broad and narrow, enlarge only symplastically in tangential direction. Rays play a special role in regulating intrusive enlargement of vessel elements. Abstract The aim of this study was to analyse relations occurring between vessel elements and surrounding cells, i.e. susceptibility to separation of walls of cells occurring in the vicinity of vessel elements, with regard to their type—cells of the axial/radial system. On the basis of separation/lack of separation of cell walls, and thus change in cell contacts/lack of change in cell contacts, we have estimated the contribution of particular types of growth—intrusive and symplastic—in …
Lignin Inter-Diffusion Underlying Improved Mechanical Performance of Hot-Pressed Paper Webs
2021
Broader use of bio-based fibres in packaging becomes possible when the mechanical properties of fibre materials exceed those of conventional paperboard. Hot-pressing provides an efficient method to improve both the wet and dry strength of lignin-containing paper webs. Here we study varied pressing conditions for webs formed with thermomechanical pulp (TMP). The results are compared against similar data for a wide range of other fibre types. In addition to standard strength and structural measurements, we characterise the induced structural changes with X-ray microtomography and scanning electron microscopy. The wet strength generally increases monotonously up to a very high pressing tempera…
Mechanical properties of natural fiber composites produced using dynamic sheet former
2018
Composites formed from wood fibers and man-made cellulosic fibers in PLA (polylactic acid) matrix, manufactured using sheet forming technique and hot pressing, are studied. The composites have very low density (due to high porosity) and rather good elastic modulus and tensile strength. As expected, these properties for the four types of wood fiber composites studied here improve with increasing weight fraction of fibers, even if porosity is also increasing. On the contrary, for man-made cellulosic fiber composites with circular fiber cross-section, the increasing fiber weight fraction (accompanied by increasing void content) has detrimental effect on stiffness and strength. The differences …
Evaluating the presence of microplastics in striped dolphins (Stenella coeruleoalba) stranded in the Western Mediterranean Sea.
2020
Litter is a well-known problem for marine species; however, we still know little about the extent to which they're affected by microplastics. In this study, we analyse the presence of this type of debris in Western Mediterranean striped dolphins' intestinal contents over three decades. Results indicated that frequency was high, as 90.5% of dolphins contained microplastics. Of these microplastics, 73.6% were fibres, 23.87% were fragments and 2.53% were primary pellets. In spite of the high frequency of occurrence, microplastic amount per dolphin was relatively low and highly variable (mean ± SD = 14.9 ± 22.3; 95% CI: 9.58–23.4). Through FT-IR spectrometry, we found that polyacrylamide, typic…
From glacial refugia to hydrological microrefugia: Factors and processes driving the persistence of the climate relict tree Zelkova sicula
2021
Abstract With only two tiny populations, the climate relict Zelkova sicula (Sicily, Italy) is one of the rarest trees in the world. It also represents the most marginal member of genus Zelkova that was widespread in the broadleaved forests thriving in warm–temperate climates throughout Eurasia until the Last Glacial Age. Occurring at the westernmost range of the genus under typical Mediterranean climate, the micro‐topographic settings have always appeared crucial for the survival of this relict. However, the factors and processes actually involved in its persistence in the current refugia, as well as the response of similar relict trees in arid environments, are poorly understood worldwide.…
Ingestion of microplastics and occurrence of parasite association in Mediterranean anchovy and sardine
2020
10 pages, 6 figures, 1 table, supplementary data https://doi.org/10.1016/j.marpolbul.2020.111399
Carvacrol activated biopolymeric foam: An effective packaging system to control the development of spoilage and pathogenic bacteria on sliced pumpkin…
2021
Abstract A commercial biodegradable starch-based polymer (Mater-Bi) was activated with carvacrol to develop a biodegradable and compostable polymer to be used in food packaging. Based on previous tests, carvacrol was added at 20 % weight of foam. MB foams, with and without carvacrol, were tested for their morphological characteristics, mechanical tests and kinetics of carvacrol release under refrigerated storage conditions. Carvacrol slightly increased the porosity of the foams, induced a reduction of the compressive elastic modulus (Ecom) of foamed MB from 6 to ∼ 3.4 MPa and a decrease of the tensile elastic modulus from ∼70 MPa to ∼16.5 MPa. Carvacrol release from the foam at 4 °C was alm…
Fresh-cut storage of fruit and fresh-cuts affects the behaviour of minimally processed Big Bang nectarines ( Prunus persica L. Batsch) during shelf l…
2018
Abstract Nectarine can be minimally processed to successfully produce ready-to-eat fresh-cuts fruit. The aim of this work was to study the combined effect of the ripening stage of cold stored fruit before processing and the length of the storage period of fresh-cut slices after minimal processing, on the behaviour of minimally processed “Big Bang” nectarines during shelf life. ‘Big Bang’nectarine slices obtained from fruit stored at 1 ± 0.5 °C (RH = 90%) for 1 d, 10 d and 15 d were stored for 0, 3, 5, 7, 12 d. at 5 °C. At the end of each storage period, visual quality, color (L*, a* and b*), phenols and carothenoids content, TSS, TA were measured together with in-package CO2 and O2. Despite…
Thermoplastic starch and green tea blends with LLDPE films for active packaging of meat and oil-based products
2019
International audience; Thermoplastic starch (TPS) is an alternative biomaterial that can be used to produce bioplastics to replace petroleum-based food packaging. Active films were developed from acetylated cassava TPS and green tea using the blown extrusion process. Green tea (GT) and TPS from native starch (NS) and acetylated starch (AS) with different degrees of substitution (DS) were extruded with linear low-density polyethylene (LLDPE) at LLDPE/TPS-GT ratios of 70/30 and 60/40 prior to blown-film extrusion. Results indicated that a higher DS of AS enhanced melt flow index which altered processability and subsequently impacted film microstructures and physical and barrier properties. N…