Habitat-Specific Morphological Variation among Threespine Sticklebacks (Gasterosteus aculeatus) within a Drainage Basin

Habitat-specific morphological variation, often corresponding to resource specialization, is well documented in freshwater fishes. In this study we used landmark based morphometric analyses to investigate morphological variation among threespine sticklebacks (Gasterosteus aculeatus L.) from four interconnected habitat types within a single lowland drainage basin in eastern England. These included the upper and lower reaches of the river, the estuary, a connected ditch network and a coastal salt marsh. We found significant habitat-specific differences in morphology, with three axes of variation describing differences in orbit diameter, body depth, caudal peduncle shape and pectoral fin positioning as well as variation in relative dorsal and pelvic spine size. Interestingly, the ditch system, an artificial and heavily managed habitat, is populated by sticklebacks with a characteristic morphology, suggesting that human management of habitats can in some circumstances lead to morphological variation among the animals that inhabit them. We discuss the mechanisms that conceivably underlie the observed morphological variation and the further work necessary to identify them. Finally, we consider the implications of habitat-specific body shape variation for the behavioural ecology of this ecologically generalist species

Polystyrene cellulose fiber composites: effect of the processing conditions on mechanical and dynamic mechanical properties

ABSTRACT The usage of natural fibers on the composites development has grown rapidly in the recent years due to the fibers plentiful availability, renewable source, low density and biodegradability. However, there are some drawbacks, for instance, the fiber dispersion on a polyolefin matrix. In this work, the influence of processing speed on the mechanical and dynamic mechanical properties of polystyrene (PS) filled with cellulose fiber composites was investigated. The composites were processed on a twin-screw co-rotating extruder, using screw speeds of 200 rpm, 400 rpm and 600 rpm. The dynamic mechanical properties and the mechanical properties were investigated as a function of fiber content. The composites processed on a screw speed of 400 rpm had presented an increase on flexural and impact strength, compared to the composites processed at 200 rpm. The flexural and storage modulus had increased when increasing the fiber content, as well as increasing the processing speed. The greater fiber dispersion obtained at a screw speed of 400 rpm hinders the agglomeration arrangement and distributes the fibers more equally on the matrix. The increase on processing speed probably generates a fiber size reduction, increasing the fiber superficial area and generating a greater contact with the matrix as well. Therefore, the efforts transference of matrix to fibers is improved, originating an increase on the evaluated properties

Elastic, crosslinked poly(acrylic acid) filaments

Hybrid monofilaments of poly(acrylic acid) (PAA) and 1,6-hexanediol diglycidyl ether (16DGE), compounded with nanofibrillated cellulose (NFC) and graphene, were thermally crosslinked and subsequently spun from aqueous solution. Crosslinking, in the form of ester linkage formation, between PAA and 16DGE was successfully achieved via thermal induction. The monofilaments were elastic and flexible in nature, displaying remarkable elongation and work-to-break values (up to nine times higher than pure PAA-16DGE filaments). This unique behaviour derives from a synergy between the fillers; namely the reinforcing ability of cellulose nanofibrils and the lubricating effect of graphene.Peer reviewe

Histomorphometric characteristics of immune cells in small intestine of pigs perorally immunized with vaccine candidate F18ac+ nonenterotoxigenic E. coli strain

Colidiarrhea and colienterotoxemia caused by F4+ and/or F18+ enterotoxigenic E. coli (ETEC) strains are the most prevalent infections of suckling and weaned pigs. Here we tested the immunogenicity and protective effectiveness of attenuated F18ac+ non-ETEC vaccine candidate strain against challenge infection with F4ac+ ETEC strain by quantitative phenotypic analysis of small intestinal leukocyte subsets in weaned pigs. We also evaluated levamisole as an immune response modifier (IRM) and its adjuvanticity when given in the combination with the experimental vaccine. The pigs were parenterally immunized with either levamisole (at days -2, -1 and 0) or with levamisole and perorally given F18ac+ non-ETEC strain (at day 0), and challenged with F4ac+ ETEC strain 7 days later. At day 13 the pigs were euthanatized and sampled for immunohistological/histomorphometrical analyses. Lymphoid CD3+, CD45RA+, CD45RC+, CD21+, IgA+ and myeloid SWC3+ cell subsets were identified in jejunal and ileal epithelium, lamina propria and Peyer’s patches using the avidin-biotin complex method, and their numbers were determined by computer-assisted histomorphometry. Quantitative immunophenotypic analyses showed that levamisole treated pigs had highly increased numbers of jejunal CD3+, CD45RC+ and SWC3+ cells (p<0.05) as compared to those recorded in nontreated control pigs. In the ileum of these pigs we have recorded that only CD21+ cells were significantly increased (p<0.01). The pigs that were treated with levamisole adjuvanted experimental vaccine had significantly increased numbers of all tested cell subsets in both segments of the small intestine. It was concluded that levamisole adjuvanted F18ac+ non-ETEC vaccine was a requirement for the elicitation of protective gut immunity in this model; nonspecific immunization with levamisole was less effective, but confirmed its potential as an IRM

Tailor-made hemicellulose-based hydrogels reinforced with nanofibrillated cellulose

Extracted and purified hemicelluloses from different plant sources were reported to be suitable crosslinkers in the synthesis of polymeric networks, such as hydrogels. These hydrogels were reported to have a possible medical application or to be part of water purification set-ups. To make these different applications possible, the produced hydrogels need to have specific chemical and physical properties. One way to tailor the final characteristics of the hydrogels is the defined modification of the hemicelluloses in order to generate highly effective hemicellulose-based crosslinkers. In this work, the synthesis of Omicron-acetyl galactoglucomannan derivatives bearing methacrylic functional groups were studied and the produced crosslinkers were applied in the synthesis of various hydrogels with various swelling degrees. In order to improve the mechanical strength of the hydrogels, the application of softwood or hardwood nanofibrillated cellulose (NFC) as a reinforcement material in the cationic hydrogels was studied. Fourier Transform Infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), and scanning electron microscopy (SEM) and static compression measurements were applied to characterize the GGM derivatives and the GGM-based hydrogels. The GGM-based hydrogels were tested in respect to their capacity to remove chromate ions from aqueous solutions and the obtained results underline the high potential of such biocomposites

Enzymatically fibrillated cellulose pulp-based monofilaments spun from water; enhancement of mechanical properties and water stability

Water-based spinning dopes composed of enzymatically fibrillated pulp (EFP), poly(vinyl alcohol) and glutaraldehyde crosslinker were successfully spun into monofilaments. Specimens containing EFP concentrations of 50 and 60 wt% were obtained utilising a customised spinning system based on a syringe pump. Monofilaments exhibited high stiffness, good strength and low strain; maximum tensile values were obtained at a cellulose concentration of 60 wt%. Reduced graphene oxide was incorporated into the monofilaments as a lubricant, enhancing elongation while also providing a slight reinforcing effect. Mechanical behaviour was dictated by a synergy of competing interaction-types and mechanisms. Selected monofilaments were coated with cellulose acetate propionate, resulting in enhanced water strength and stability. The stability of the monofilaments was demonstrated in their ability to be tied into a knot, and to be used to prepare two- and three-dimensional structures