Improvement of toughness for the hyaluronic acid and adipic acid dihydrazide hydrogel by PEG

New applications call for many new requirements. In order to improve the toughness of aldehyde hyaluronic acid (A-HA) and adipic acid dihydrazide (ADH) hydrogel, the poly(ethylene glycol) (PEG) was added. PEG content and molecular weight have little effect on the gelation time, and the composite hydrogels can form in situ within 20 seconds at room temperature. The press test showed that the hydrogels containing PEG possessed a better compression resistance, after pressed more than five times, the composite hydrogels could restore. Rheological properties were measured to evaluate the working ability and the effect of PEG on hydrogels. By analyzing the shear viscosity (η _γ=0.01), yield stress (σ ₀) and threshold shear stress (σ _c ), the addition of PEG can make the structure of composite hydrogels get loose and improve the shear resistance. Especially, PEG800 can enhance the antishear ability obviously. The amplitude sweep tests showed a broad linear viscoelastic region, indicating a wide processing range. In the meanwhile, we also found that PEG can improve the optical transmittance of xerogel evidently.     

Synthesis and Characterization of Superabsorbent Polymer Based on Carboxymethyl Cellulose-<Emphasis Type="Italic">graft</Emphasis>-Itaconic Acid

Superabsorbent polymers of carboxymethyl cellulose-graft-itaconic acid were synthesized using potassium persulfate as a free radical initiator in the presence of N,N′-methylene bisacrylamide as a crosslinker using solution polymerization technique. The structures of the grafted copolymers were characterized by FT-IR spectroscopy and thermogravimetric analysis. The effect of reaction variables such as concentration of carboxymethyl cellulose, itaconic acid, initiator, crosslinker, and neutralizing agent were optimized to achieve a hydrogel with high swelling capacity of 74 g/g (DI water) and 18 g/g (0.9 wt% NaCl solution). The swelling kinetics of the prepared SAP were analyzed by applying the Fickian diffusion model and the Schott’s pseudo second order kinetics model. The diffusion exponents in the Fickian model, n, showed values of 0.73-0.93, indicating that chain relaxation behavior during absorption had a large effect on total absorbency.     

Removal of some cationic dyes from aqueous solution by acrylamide- or 2-hydroxyethyl methacrylate-based copolymeric hydrogels

In this study, anionic hydrogels were prepared using a crosslinker (N,N′-methylenebisacrylamide) through a free radical addition reaction in aqueous solutions of neutral acrylamide or 2-hydroxyethyl methacrylate monomer and anionic monomers, mesaconic acid or aconitic acid. Cationic dyes along with safranine (azine-), nile blue (oxazine-) and methylene blue (thiazine-) were selected as models of pollutants, and adsorption of these dyes onto the hydrogels was investigated. To examine the effect of concentration on adsorption, dye solutions prepared with a concentration range of 5–50 mg l^?1 and 0.1 g hydrogel at 25 °C were exposed to the hydrogels until equilibrium was established. Dye adsorption onto the hydrogels was found to be an L type Giles adsorption isotherm. Monolayer sorption capacity and adsorption constant values were calculated from the Langmuir plots. To calculate R_L values, a non-dimensional analysis was used and they were always found to be 0<R<1. In other words, the hydrogels were favorable for adsorption of these dyes. Aqueous solutions of dyes were observed to interact with hydrogels in the following order: oxazine > azine > thiazine. Furthermore, the higher the number of carboxyl groups in the hydrogel composition, the higher the adsorbed amount of substance.     

Fabrication of silver nanoparticle/polyvinyl alcohol/polycaprolactone hybrid nanofibers nonwovens by two-nozzle electrospinning for wound dressing

In this study, two biodegradable polymers, polycaprolactone (PCL) and polyvinyl alcohol (PVA) were used to fabricate nanofiber nonwovens (NFNs). Also, the silver nanoparticles (AgNPs) successfully reduced by using tea polyphenols (TP) and incorporated in the NFNs via electrospinning. The morphologies of the NFNs and AgNPs were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), respectively. The PCL nanofibers and PVA nanofibers interweaved each other, and AgNPs with average diameter 1.53±0.15 nm were embedded in the PVA nanofibers. The properties of electrospun NFNs were characterized by pore property, swelling/weight loss, water contact angle, mechanical property, and antibacterial activity. The nanofibers cross-linked to each other forming the 3Dnetwork porous structure with diameter about 1-1.5 μm. Although the hydrophobic PCL was added in the hybrid NFNs, the NFNs still showed hydrophilic propriety, high swelling degree (i.e. swelling degree is 330 % for 48 h), and low weight loss (i.e. weight loss is 22.4 % for 48 h). Also, the hybrid PCL/PVA/AgNPs NFNs exhibited a suitable mechanical property for wound dressings (i.e. tensile strength is 4.27 MPa, and breaking elongation is 88 %). Moreover, the hybrid NFNs effectively inhibited growth of Escherichia coli and Staphylococcus aureus. In summary, this PCL/PVA/AgNPs NFNs may provide a promising candidate for accelerating wound healing.     

Dyeability and Antibacterial Finishing of Hemp Fabric Using Natural Bioactive Neem Extract

Two functional compounds were successfully extracted from neem (Azadiracta indica): a tannin-rich natural dye and an antibacterial agent. The dye was extracted from the bark using water, and the antibacterial from the leaf using methanol. These were used to dye hemp fabrics. Higher color strength values (K/S) were found when dyeing was conducted at a higher dye concentration, elevated temperature, and longer dyeing time. Optimal results were achieved when using 5 %w/v of extracted powder at 100 °C for 60 min. The resulting fabrics appeared reddish-brown, and were rated as good to excellent for color fastness against washing, water, sea water, and perspiration. The antibacterial agent from the neem leaf was extracted by Soxhlet apparatus at 65 °C with methanol as solvent. The dyed and antibacterial-finished hemp fabrics were tested against Staphylococcus aureus, following the percentage reduction test of AATCC 100. The treated fabrics demonstrated a 99.99 % reduction in Staphylococcus aureus.     

<Emphasis Type="Italic">Limoniastrum monopetalum</Emphasis> stems as a new source of natural colorant for dyeing wool fabrics

In the present study, an attempt has been made to dye the wool fabric with Limoniastrum monopetalum stems, as a source of natural dye, which has not been exploited so far. Optimization of extraction parameters was done. Optimum results of extraction process were obtained with a dye concentration of 60 g/l, a temperature of 90 °C during 100 min. The study of different factors effecting dyeability of wool fabrics by aqueous L. monopetalum stems extract showed that the pH of dye bath and dyeing temperature and time affected considerably the color yield. The best results were obtained at the following conditions; pH 2, 100 °C, and 60 min. Metal mordants, when used in conjunction with L. monopetalum dye, allowed to obtain various shades. The determination of phenolic contents of aqueous L. monopetalum stems extract showed a high amount of phenolic components. Based on RP-HPLC, the coloring extract of L. monopetalum stems contains tannins and polyphenols. The major identified phenolic compounds were procatechuic, Trans-cinnamic and gallic acids. Hence, aqueous L. monopetalum stems extract could be successfully exploited for dyeing wool fabrics with high color yield (K/S).     

Extraction,Dyeing, and Antibacterial Properties of <Emphasis Type="Italic">Crataegus Elbursensis</Emphasis> Fruit Natural Dye on Wool Yarn

Fruits obtained from shrubs of the Crataegus elbursensis (C. elbursensis) plant demonstrate significant antioxidant and antibacterial properties. In this study, natural dye was sono-extracted from fresh and dried fruits and applied in dyeing and antibacterial finishing of wool. The maximum sono-extraction yield was obtained when optimal conditions of ethanol/ water (4/1 v/v) as extracting solvent, time 30 min, pH 4, temperature 50 oC, and C. elbursensis concentration 10 g/l were used. When wool yarns were dyed with the extracted natural dye, the maximum dye uptake was achieved using dye concentration 75 % owf, and dyeing condition of 100 oC, 60 min, pH 4, and LR 100:1. Different metal salts like aluminum sulfate, copper sulfate, and tin chloride were applied on wool by pre-mordanting method and their effects on dye uptake, color variation, and color fastness were examined. Results showed that the natural dye itself had relatively high uptake and good color fastness on un-mordanted wool. Further, each mordant had different effect on dye uptake, color variation, and color fastness properties depending on its coordination ability with dye molecules and wool chains. Moreover, dyed yarns showed good antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria.     

Direct dye removal by using UV/hydrogen peroxide/multiwalled carbon nanotubes

In this study, decoloration of Direct Blue 71 (DB71) and Direct Red 23 (DR23) has been discussed by using Multiwalled Carbon Nanotubes (MWCNTs) and Hydrogen peroxide under UV radiation. The purpose of this study is removal of organic compounds by using carbon nanotubes that are effective adsorbents for different types of pollutants, due to their porous nature and large surface area. It also causes catalytic decomposition of hydrogen peroxide. Adsorption rate was investigated under various parameters (initial dye concentration, salt, temperature and pH). The main objective of this study is to appraise the synergic effect between H₂O₂ and MWCNTs under UV radiation. The dye adsorption results of spectrophotometer, showed that by decreasing the dye concentration from 0.2 g/l to 0.05 g/l with the optimal value of MWCNTs 0.2 g/l and hydrogen peroxide 2 g/l at pH=4 and 6 cm distance from the UV lamp, the dye removal increased.     

Application of MCT-βCD to Modify Cellulose/Wool Blended Fabrics for Upgrading Their Reactive Printability and Antibacterial Functionality

Pre-loading of monochlorotriazinyl β-Cyclodextrin (MCT-βCD) onto/within viscose/wool (V/W) and cotton/wool (C/W) blended fabrics provide hosting cavities that can form host-guest inclusion complexes with reactive dyes in postprinting as well as with triclosan derivative or silver nanoparticles/hyperbranched polyamide-amine (AgNPs/HBPAA) composite in subsequent final antibacterial finishing step. Coloration properties, antibacterial activity against (S. aureus) and (E. coli) pathogenic bacteria, durability of the obtained products, according to the above mentioned route, to wash, surface morphology and composition of selected samples were investigated. Results obtained signify that premodification of the nominated substrates with MCT-βCD (10 g/l), followed by reactive printing with mono-or bifunctional reactive dye (20 g/l), and subsequent post-finishing with triclosan derivative or AgNPs/HBPAA composite (15 g/l each) is an efficient treatments sequence for attaining reactive prints with significant antibacterial efficacy and noticeable durability to wash. Surface depositions of selected active ingredients were also confirmed using SEM and EDX analysis.     

Effects of willow hybridisation and simulated browsing on the development and survival of the leaf beetle <Emphasis Type="Italic">Phratora vitellinae</Emphasis>

Background

Interspecific hybridisation is common between many plant species and causes rapid changes in a variety of plant characters. This may pose problems for herbivores because changes in recognition characters may be poorly correlated with changes in quality characters. Many studies have examined different systems of hybrids and herbivores in attempts to understand the role of hybridisation in the evolution of plant resistance. The results from different systems are variable. Studies of hybrids between Salix caprea (L., Salicaceae) and S. repens show that they are intermediate between the two parental species in most resistence characters. However, a plants herbivore resistence depends also on its biotic and abiotic environment. Important biotic factors that may influence plant growth and plant chemistry include the interactions between different herbivores that occur through their exploitation of common host plants. Although the effects on plants of previous herbivory are likely to be strongly affected by environmental conditions, they are also species-specific. Damage may therefore have different effects on hybrids than on their parental species, and this could influence the performance of herbivores on pure and hybrid species of plants. To evaluate the effects of hybridisation on insect performance, the development and survival rates of Phratora vitellinae (L. 1758, Coleoptera: Chrysomelidae) larvae on pure S. repens, pure S. caprea and Fl hybrids of the two species was monitored. Further, to examine the effect of herbivorous mammals on the performance of the larvae, plants were damaged to simulate winter foraging by voles or spring leaf stripping by moose.

Results

The results show that development rates were highest on S. repens and equally low on S. caprea and the Fl hybrid. In addition, development of the plants treated to simulate mammalian herbivore damage was slower than that of corresponding controls.

Conclusions

The results of this experiment suggest that P. vitellinae has a higher development rate, and thus probably higher performance, on species with high concentrations of phenolic glucosides. Therefore, it would be of adaptive benefit for P. vitellinae females to have an ovipositional preference for S. repens, compared to S. caprea and intermediate preference for Fl hybrids. The faster development observed on S. repens supports the hypothesis that P. vitellinae obtains additional adaptive benefits from phenolic glucosides beyond protection against predators. Therefore, it is important to consider further factors, such as damage caused by other herbivores, when studying this hybrid complex.

     

Preparation and characterization of electrospun polyvinyl alcoholstyrylpyridinium/<Emphasis Type="Italic">β</Emphasis>-cyclodextrin composite nanofibers: Release behavior and potential use for wound dressing

Biocompatible polyvinyl alcohol (PVA)-styrylpyridinium (SbQ)/β-cyclodextrin (β-CD) composite nanofibers were obtained by electrospinning in this study. PVA-SbQ was used as the foundation polymer as well as crosslinking agent, β-CD was incorporated to achieve expected properties such as improved mechanical properties and thermal stability. The Fourier transform infrared spectroscopy (FTIR) spectra confirmed the existence of β-CD, and the morphologies and average fiber diameters of the electrospun composite nanofibers were also analyzed by SEM. X-ray diffraction patterns (XRD) of PVA-SbQ/β-CD composite nanofibers revealed that the inclusion of β-CD in the nanofibers affected the ordered phase of PVA. Besides, the thermal analyses revealed the improvement in the thermal properties for PVA-SbQ/β-CD composite nanofibers. It was found that the crosslinked composite nanofibers showed a clear higher tensile strength (TS) as well as a greater elongation at break (EB). Eventually, antifungal drug griseofulvin (GSV) has been loaded into the composite nanofibers by formation of its inclusion complex with β-CD in aqueous solution, ultraviolet light (UV-Vis) spectral analysis showed that the drug-loading nanofibers had certain sustained release effect.     

Bioactive and multifunctional textile using plant-based madder dye: Characterization of UV protection ability and antibacterial activity

In the present work the natural madder dye (Rubia tinctorum L.) was applied to the simultaneous dyeing and functionalization of polyester (PET) fabric. In the first part of the study the color performance and the durability were revealed for exhaustion dyed fabric. The dyed fabric was then characterized with respect to ultraviolet (UV) protection ability and antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). CIELab color coordinates, namely the positive a* and b* values, confirmed a yellow/orange color of the dyed fabric. From durability tests, the color showed a moderate to good light fastness and good to excellent fastness to washing and rubbing. The madder dye improved both the UV protective performance and the antibacterial activity of the fabric. With 3 % on weight of fiber (owf) the UV protection factor increased up to 106, and the antibacterial activity up to 86 % against both types of bacteria tested.     

<Emphasis Type="Italic">OsLAP6/OsPKS1</Emphasis>, an orthologue of <Emphasis Type="Italic">Arabidopsis PKSA/LAP6</Emphasis>, is critical for proper pollen exine formation

Background

Male fertility is crucial for rice yield, and the improvement of rice yield requires hybrid production that depends on male sterile lines. Although recent studies have revealed several important genes in male reproductive development, our understanding of the mechanisms of rice pollen development remains unclear.

Results

We identified a rice mutant oslap6 with complete male sterile phenotype caused by defects in pollen exine formation. By using the MutMap method, we found that a single nucleotide polymorphism (SNP) variation located in the second exon of OsLAP6/OsPKS1 was responsible for the mutant phenotype. OsLAP6/OsPKS1 is an orthologous gene of Arabidopsis PKSA/LAP6, which functions in sporopollenin metabolism. Several other loss-of-function mutants of OsLAP6/OsPKS1 generated by the CRISPR/Cas9 genomic editing tool also exhibited the same phenotype of male sterility. Our cellular analysis suggested that OsLAP6/OsPKS1 might regulate pollen exine formation by affecting bacula elongation. Expression examination indicated that OsLAP6/OsPKS1 is specifically expressed in tapetum, and its product is localized to the endoplasmic reticulum (ER). Protein sequence analysis indicated that OsLAP6/OsPKS1 is conserved in land plants.

Conclusions

OsLAP6/OsPKS1 is a critical molecular switch for rice male fertility by participating in a conserved sporopollenin precursor biosynthetic pathway in land plants. Manipulation of OsLAP6/OsPKS1 has potential for application in hybrid rice breeding.

     

Fabrication,Characterization and Antimicrobial property of natural TTOLs/CS composite sponges

The essential oil liposomes, a kind of ecological friendly natural antibacterial agents, have good bactericidal effect. In the present study, tea tree oil liposomes (TTOLs) were prepared by the thin-membrane hydration method with sonication, and then were blended with chitosan (CS) to successfully fabricate novel TTOLs/CS composite sponges by freeze-dried method. Through the scanning electron microscope (SEM), fourier transform infrared spectroscopy (FTIR) and performance tests, it was found that the material had good water absorption, water retention and water vapor permeability due to the high porosity. Furthermore, the incorporation of TTOLs in the CS-based sponges significantly improved the microbicidel effect of the sponges against Staphylococcus aureus (S. aureus), Escherichia coli (E. coli) and Candida albicans (C. albicans). Killing log values of TTOLs/CS composite sponges against bacteria and fungi reached over 3. According to the microbial clearance test, propidium iodide (PI) fluorescence test and transmission electron microscope (TEM) observation, the results indicated on one hand that TTOLs/CS composite sponges adsorbed and intercepted microbial cells through the internal pore and surface charge, and on the other hand that they could destroy bacterial intercellular substance, disperse cell colony and damage the integrity of cell membrane, finally leading to the death of microbial cells. In summary, TTOLs/CS composite sponges had great potential to be used as antimicrobial materials in the field of food, cosmetics, medicine, biomedical and biochemical engineering.     

Mechanical properties of fragrant screwpine fiber reinforced unsaturated polyester composite: Effect of fiber length,fiber treatment and water absorption

Fragrant screwpine fiber reinforced unsaturated polyester composites (FSFRUPC) were subjected to water immersion tests in order to examine the effect of water absorption on the mechanical properties. FSFRUP composite specimen containing 30 % fiber volume fraction with fiber length of 3 mm and 9 mm was considered in this study. Water absorption test was performed by immersing specimen in sea, distilled and well water at room temperature under different time durations (24, 48, 72, 96, 120, 144, 168, 192, 216, 240 hours). The tensile, flexural and impact properties of the water absorption specimen were appraised and compared with those of the dry composite specimen as per the ASTM standard. The tensile, flexural and impact properties of FSFRUPC specimen were found to decrease with the increase in the percentage of moisture uptake. The percentage of moisture uptake of composite was reduced after alkali treatment with 3 % NaoH for 3 hours. In moisture absorption test, the lowest diffusion coefficient, D (6.62513×10^-13 m²/s) and swelling rate parameter, K _sr (6.341×10^-3 h^-1) were obtained through the specimen immersed in sea water. The chemical composition, elemental composition of fiber and surface morphology of the FSFRUPC were analysed by using Fourier transform infrared spectroscopy (FTIR), Energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM) respectively.     

Experimental Study on Antimicrobial Activity of Silk Fabric Treated with Natural Dye Extract from Neem (<Emphasis Type="Italic">Azadirachta indica</Emphasis>) Leaves

In the present study, a novel eco-friendly production of silk fabrics dyed with different natural dye bath concentrations (40, 80, 120, 160, 200 and 240 g/l) extracted from neem (Azadirachta indica) leaves was developed. The surface morphology of the fabrics was examined by scanning electron microscopy (SEM) and Fourier-transform infrared (FTIR) spectroscopy to characterize the chemical structure of the fabrics. The SEM images of the undyed fabric show that the fabric was tightly woven with little porosity between the fibres with dozens of silk threads in orthogonal directions. By increasing the neem concentration, a scale of fine particles grew on the surface of the silk fabrics with little macroscopical defects was demonstrated. The fiber diameters and tightness between filaments were significantly increased. The FTIR displayed that, neem dye does not change the characteristic peaks of the silk fabrics. Also, the evaluation of the antimicrobial activity of the undyed and neem dyed silk fabrics was monitored for Gram positive and Gram negative bacteria in addition to yeasts and fungi by using the agar diffusion method. The comparison between the different dye bath concentrations was based on the inhibition zones obtained after incubation. The antimicrobial activity in leaf extract of neem was estimated in Staphylococcus aureus, Bacillus subtilis and Lactobacillus cereus (Gram positive bacteria); Escherichia coli (Gram negative bacteria); Candida albicans and Candida tropicalis (yeasts); and Aspergillus niger and Fusarium solani (fungi). The results emphasized that, the highest neem dye bath concentration (240 g/l) was found to display good inhibitory effect against the Gram positive and reasonable activity against the Gram negative bacteria. Furthermore, the different dye bath concentrations possess no activities against yeast and fungi. In conclusion, the data reveal that the increase of neem dye concentration does not damage the silk fabric; however, it improves its antimicrobial activity by incorporating with antimicrobial agent. The current study highlighted that using neem leaves had beneficial effect in controlling the pathogenic microbial organisms.     

Dissecting combining ability effect in a rice NCII-III population provides insights into heterosis in <Emphasis Type="Italic">indica-japonica</Emphasis> cross

Background

Combining ability is a measure for selecting elite parents that make the highest contributions to hybrid performance. However, the genetic bases of combining ability and how they contributed to heterosis is seldomly known.

Results

We constructed a both NCII and NCIII population derived from an indica-japonica cross to study the relationship among parental performance, combining ability and hybrid performance of 11 agronomic traits. Among them, specific combining ability is more important to grain yield than parental performance and general combining ability. We performed linkage analyses to phenotypic values and combining ability of all 11 traits in Doubled haploid lines and its two backcross populations and identified 108 QTLs in total. Among these QTLs, four known loci, Sd1, Ghd7, Ghd8 and DEP1 contribute a lot to GCA effects of agronomic traits except grain yield and seed setting rate. Three QTLs, Ghd8, S5 and qS12, contribute a lot to SCA effects of grain yield and present overdominace.

Conclusions

Our study provides insights into the genetic bases of combining ability and heterosis and will promote the improvements of indica-japonica hybrid breeding.

     

Prevalence of the pathogenic chytrid fungus, Batrachochytrium dendrobatidis, in an endangered population of northern leopard frogs, Rana pipiens

Background

Emerging infectious diseases threaten naïve host populations with extinction. Chytridiomycosis, an emerging infectious disease of amphibians, is caused by the pathogenic fungus Batrachochytrium dendrobatidis (Bd) and has been linked to global declines in amphibians.

Results

We monitored the prevalence of Bd for four years in the Northern leopard frog, Rana pipiens, which is critically imperiled in British Columbia (BC), Canada. The prevalence of Bd initially increased and then remained constant over the last three years of the study. Young of the year emerging from breeding ponds in summer were rarely infected with Bd. Some individuals cleared their Bd infections and the return rate between infected and uninfected individuals was not significantly different.

Conclusions

The BC population of R. pipiens appears to have evolved a level of resistance that allows it to co-exist with Bd. However, this small population of R. pipiens remains vulnerable to extinction.