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The response of the polymer solution to % strain is critical since the polymer solution is drawn by the electrical field during electrospinning process. To date, all studies relating electrospinning to rheological parameters have been conducted in the linear region where small strain values are applied to the polymer solutions. This is the first study attempting to correlate the behavior of the solutions in the nonlinear region with smooth nanofiber formation. For this aim, fiber forming solutions were prepared with pectin at different concentrations (3%, 4%, 5%, and 6%) and PEO with different molecular weights (600, 1000, and 2000 kDa). Deformation was applied in the range of 0.05% and 500% and normalized Lissajous curves were obtained. Both elastic and viscous curves confirmed one another, suggesting a profound contribution of PEO 2000 to the elasticity of the polymer solution at all pectin concentrations even at large strain values. This finding might explain why smooth fibers can only be achieved with PEO 2000 while only beaded fibers were formed with PEO 600 and PEO 1000. The results suggest that LAOS measurements might be used as a promising tool to predict whether a polymer solution can be electrospun into smooth nanofibers. [ABSTRACT FROM AUTHOR]

Salinity is one of the most important factors restricting vegetative production, especially in arid and semi-arid regions. In this study, the effects of the exogenous plant growth-promoting rhizobacteria (PGPR: Bacillus pumilus UG-41, Bacillus cereus UG-50) application on seedling growth, concentration of plant nutrient elements, antioxidant activity and chlorophyll, proline, sugar, hydrogen peroxide (H2O2), malondialdehyde (MDA), hormone contents of pepper seedlings under salinity stress conditions (100 mM NaCl) were investigated. Our results showed that gibberellic acid (GA), salicylic acid (SA), indole acetic acid (IAA), leaf relative water content (LRWC) and the concentration of all plant tissue nutrients investigated except for Na were decreased by salt stress. On the other hand, PGPR treatment increased the plant growth parameters by increasing the proline, sucrose, hormone and chlorophyll contents; altering the mineral uptake and increasing the antioxidant enzyme activity in pepper seedlings under salt stress. In conclusion, PGPR treatment may be used as an effective technique to protect the plants against salinity stress since the bacteria positively impact the ability of the plant to cope with the stress by particularly increasing the antioxidant enzyme activity, hormone level and mineral uptake. [ABSTRACT FROM AUTHOR]

Walnuts (Juglans regia L.) are a good source of dietary minerals and contain significant amounts of potassium, phosphorus, magnesium and iron. In Turkey, walnut orchards are found in the Çoruh Valley and are generally composed of local varieties. Since chemical and physical properties of walnuts are very important in determining their quality, in this study, nut and kernel characteristics, fatty acid composition and phenolic composition were determined for 26 walnut genotypes collected from the valley. Total fat content was found to be between 53.75% and 71.43%, while the crude protein amount ranged from 10.21% to 20.71%. Total carbohydrates were calculated between 14.31-27.52% and ash content was found to be between 1.64% and 3.32%. The oleic acid content and linoleic acid content ranged from 18.34 to 25.58% and 37.09% to 87.51%, respectively. The linolenic acid content was determined between 5.52% and 11.03%. Our study showed that, differences in phenolic component, crude protein and fatty acid content of walnuts were caused by different growing conditions. Genotypes have a rich and stable structure in terms of fruit quality parameters, minerals, organic acids, phenolic composition, antioxidant and fatty acids amounts and amino acids. In other words, these characteristics did not show much variation in genotypes grown in the Valley. However, there was a great variation in hormone levels among genotypes. In terms of the parameters examined, GN2, GN10, GN15, GN24, GN25 and GN26 genotypes were determined as rich and stable genotypes. [ABSTRACT FROM AUTHOR]

Characterizing the parameters critical to the prediction of a successful electrospinning process from solution properties is essential, yet, not easy in the case of biopolymers. In this study, we attempted to present a broad perspective by simultaneously evaluating the effect of eight different parameters, namely zero shear viscosity, tip viscosity, elastic modulus, phase angle, cohesive energy, pH, conductivity, and surface tension, on the formation of smooth pectin nanofibers. Our results showed that (1) the viscosity of the solution is not an indication of jet formation, but once the jet is formed, high zero shear viscosity and high tip viscosity are required to maintain a dominant whipping instability for smooth nanofiber formation and (2) while evaluating the elasticity of the spinning solutions, comparing only the elastic modulus values would be misleading, since low phase angle values are also necessary for pectin solutions to be electrospun into nonbeaded fibers. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48294. [ABSTRACT FROM AUTHOR]

Plant biostimulants are microorganisms (PGPR) and/or products obtained from different organic substances that positively affect plant growth and efficiency and reduce the negative effects of abiotic challenges. Effects of biostimulants on the plant growth, yield, mineral content, antioxidant enzyme activity, H2O2, malondialdehyde (MDA), sucrose, and proline contents of cherry tomato (Solanum lycopersicum var. cerasiforme L.) grown in soils with two different characteristics were investigated during a pot study under greenhouse conditions. Soil I was a fertile routinely vegetable-cultivated soil. Soil II had high salinity, high CaCO3 content, and low organic matter content. Commercial biostimulant products Powhumus® (PH), Huminbio Microsense Seed® (SC), Huminbio Microsense Bio® (RE), and Fulvagra® (FU) were used as seed coatings and/or drench solutions. All biostimulant treatments improved the plant growth and yield compared with the control in both soils. All biostimulant applications were more effective in soil II than in soil I. RE was the most effective application for mineral content in soil I, whereas FU was the most effective in soil II. Antioxidant activity, H2O2, MDA, and proline contents were decreased in both soils when biostimulants were used compared with the control. Peroxide (POD) activity was greater with SC1 in soil II. The RE treatment increased the sucrose content in soil II. In conclusion, single and combined use of high-purity fulvic acid and PGPR had positive effects on the growth of cherry tomato in fertile soil and under stressed conditions. [ABSTRACT FROM AUTHOR]