The current research discusses the efforts to achieve a Poly(lactide-co-glycolide)(PLGA) nanofiber yarn using two differently charged nozzles with potential application as surgery suture. First, electrospinning parameters such as solution concentration, applied voltage, feed rate were optimized to produce yarn with smooth nanofibers. In order to improve the properties of produced suture, heat setting setup was developed. Two heat setting techniques, including hot water and dry heat were applied, and the influence of the heat setting process on the mechanical properties of yarn was studied. The results showed that heat setting with boiling water was the best method. At first strength, E-modulus and extension of prepared suture were 36.6 MPa, 0.9 GPa and 68.8 % respectively. After improvement with heat setting, strength and E-modulus increased to 63.7 MPa, 2.7 GPa respectively and extension decreased to 29.7 %. Finally, in order to analyze knot performance, two types of surgical knot (square and surgeon) were used, and mechanical properties were investigated. The presence of knot lessens mechanical properties for each two type. Square knot showed better mechanical properties than surgeon’s knot. With square knot strength, E-modulus and extension were 62.1 MPa, 2.1 GPa, 28.6 %, respectively. In vitro study of nanofiber yarn degradation behavior showed that the mechanical properties were decreased. This could be due to greater surface area of nanofibers exposed to surrounding environment. 相似文献
This paper explores the salt-tolerance response of Melilotus species, a forage legume, based on tolerance/susceptibility indices, leaf water relations, leaf/root ion concentrations and multivariate (factor and function discriminate) analyses. In a greenhouse experiment, salinity-susceptibility of 12 accessions of Melilotus (M. albus, M. indicus, M. officinalis) in addition, two controls (alfalfa and Persian clover) were evaluated at 0 mM, 100 mM, 200 mM, and 300 mM of sodium chloride (NaCl). The experiment was conducted in a split plot design with two replications. Stress tolerance score (STS) was calculated based on tolerance/susceptibility indices. Salt-tolerant accessions were identified. An extracted bi-plot based on factor analysis confirmed the results of tolerance/susceptibility indices. There were significant correlations between STS and multivariate statistics. Root potassium cation (K+) concentration was higher in Melilotus species than the control species in all the salinity treatments. STS, root K+ concentration, leaf turgidity, and leaf succulence characteristics can be used for screening salinity-tolerance in Melilotus accessions. In all treatments, M. officinalis, M. indicus, and M. albus were salinity-tolerant species in descending order.
Abbreviations: Total biomass yield under control (Yp) and stress (Ys) mediums, geometric mean productivity (GMP), leaf area (LA), leaf tissue density (LTD), linear regression coefficient (b), mean productivity (MP), relative water content (RWC%), Succulence (S), specific leaf area (SLA), stress susceptibility index (SSI), stress tolerance index (STI), tolerance (TOL), water content at saturation (WCS), water saturation deficit (WSD), sodium chloride (NaCl), potassium cation (K+), sodium cation (Na+), analysis of variance (ANOVA), least significant difference (LSD), alfalfa control accession (CHA), Persian clover control accession (CHC), coefficient of variation (CV), statistics of factor (F) and discriminate function (D) 相似文献
Polyglycolic acid-poly lactic glycolic acid (PGA-PLGA) electrospun nanofibers containing silver nanoparticles have been produced and twisted into the nanofibrous yarn. The morphology of nanofibers and produced yarns, as well as the mechanical properties of the yarns, were investigated. Furthermore, in vitro antibacterial properties and in vitro degradation behavior of yarns containing various silver nanoparticles were studied. SEM images confirmed that the addition of the silver nanoparticles into the polymer solution increases the fiber diameters. The result of the mechanical test of the yarns alone and used in two different forms of the knots was measured and results showed that the strength of the yarns without the knot was significantly more than that of others. The biodegradability test showed that the mechanical properties and the weight of the yarns were quickly reduced after subjecting to in vitro condition. The result of the antibacterial test indicated that the nanofiber yarns containing %3 silver nanoparticles were the most appropriate sample with a considerably antibacterial activity against both gram-positive bacterium Staphylococcus aureus and gram-negative bacterium Escherichia Coli with inhibition zones of 8.1 and 9.5 mm, respectively; which demonstrated that silver nanoparticles retained their effectiveness after the electrospinning process. Therefore the nanofibrous yarns containing silver nanoparticles could be successfully produced by the electrospinning process with the proper antibacterial property as a candidate for the surgical sutures. 相似文献
When an accidentally introduced pest establishes in the invaded area, native natural enemies may adapt to the new host. A decade after the accidental introduction of the brown marmorated stink bug, Halyomorpha halys, in Europe, two generalist native egg parasitoids, the eupelmid Anastatus bifasciatus and the encyrtid Ooencyrtus telenomicida, have been recorded from this invasive agricultural pest in the field. Both species are able to complete development to the adult stage within the new host. Trissolcus basalis (Platygastridae = Scelionidae), which is not associated with H. halys in the field, was reared from freeze-killed sentinel eggs placed on soybean plants in central Italy. We tested in a Y-tube olfactometer the behavioural responses of these egg parasitoids to volatiles from H. halys adults and from Vicia faba plants attacked by H. halys. Both A. bifasciatus and O. telenomicida positively responded to adult H. halys male volatiles and to H. halys-induced plant volatiles, indicating ability to exploit cues associated with the new host for egg location, whereas T. basalis only reacted to female volatiles. A. bifasciatus and O. telenomicida are generalist egg parasitoids, showing a much wider host range when compared to T. basalis. On the other hand, platygastrid egg parasitoids from the native area of H. halys, considered for classical biological control, may be too risky due to the possibility of attacking non-target species, including predaceous stink bugs. Therefore, indigenous A. bifasciatus and O. telenomicida are presently under evaluation for augmentative biological control of H. halys in Europe. 相似文献
This paper reports an improved version of the numerical method used in a previous study on the dynamic simulation of purse
seine gear in three dimensions. The improvement is achieved by refining the mass–spring model to take into account both the
drag coefficient as a function of the attack angle and Reynolds number as applied to the setting operation of the purse seine
gear. The validity of the numerical simulation is assessed by comparing the measured and calculated values for the sinking
depth of the net. The numerical simulation is used to examine the sinking performance of the different designs in which large
meshed-panels and netting materials are used together in the main body section of the netting. The results indicate that,
compared to the prototype net, nets bearing larger mesh panels require more sinking depth with much more pronounced operational
depth at corresponding times of the fishing operation when heavier netting material is used. Moreover, in the new net designs,
lower tensile forces are exerted on both ends of the pure wire during pursing. The new net constructions with regard to the
operational depth represent alternatives that may reduce the potential problem of frequent failed setting of the tuna purse
seine gear. 相似文献
In this research, poly(vinyl alcohol) (PVA)/chitosan electrospun nanofibrous membrane (ENM) was prepared by electrospinning method in order to investigate its dye removal ability from colored wastewater. The morphology and average fiber diameter of the membranes were investigated by scanning electron microscopy (SEM), image analysis and atomic force microscopy (AFM). The chemical characterization was studied by Fourier transform infrared spectroscopy (FTIR). The permeability of the membranes was evaluated by measuring pure water flux (PWF). In order to investigate the performance of the prepared membranes they were used in the batch adsorption and membrane separation for dye removal from colored wastewater. The effect of pH, number of membranes and dye concentration on the dye removal ability of the ENM was investigated. Response surface methodology (RSM) was used to achieve multi-objective optimization and equations of adsorption capacity and breakthrough time regarding operating conditions. The results demonstrated the potential of using PVA/chitosan nanofiber membrane as a microfiltration (MF) membrane for dye removal. Moreover, the recoverability property of prepared membranes was noticeable. 相似文献
Bay essential oil (BEO) at 0.5 and 1 g/100 g was added to surimi gels fortified with omega (ω)-3 rich oils. Although the fortification resulted in increased (P < 0.05) susceptibility of surimi to lipid oxidation, 0.5 g/100 g BEO significantly reduced TBARS (P < 0.05). Addition of ω-3 rich oil or BEO improved the texture. Color values of the surimi seafood were improved particularly when BEO was added. Sensory properties, water activity, and pH values were generally within the acceptable range. These results suggest that the incorporation of BEO may allow food manufacturers to nutritionally enhance surimi seafood with beneficial ω-3 rich oils. 相似文献