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In this research, polyoxyethylene with alkyne end groups and two disulfide bonds in the polymer chain was synthesized through two consecutive esterification reactions from polyethylene glycol (PEG). A new PEG-based hydrogel with exceptional structural features was prepared from the polycycloaddition reaction of this macro-dialkyne with a triazidohydrin obtained from trimethylolpropane triglycidyl ether. The network structure of the hydrogel was investigated by FT-IR spectroscopy, elemental analysis, field emission-scanning electron microscopy (FE-SEM) and energy dispersive X-ray (EDX) spectroscopy. The swelling behavior of the prepared hydrogel in water was studied by drawing the graph of water uptake percentage versus time. It was found that the hydrogel has the ability to absorb water more than five times its dry weight within 12 h. The water uptake rate of the prepared hydrogel was compared with several other hydrogels with similar structure. In addition to water, the swelling behavior was also checked in a number of organic solvents with different dipole moments. The prepared hydrogel showed significant solvent uptake (slightly more than twice the dry weight) in methanol and N,N-dimethylformamide solvents. [ABSTRACT FROM AUTHOR]

Biopolymers such as chitosan (CHT) or alginate (ALG) are among the most prominent for health-related applications due to their broad bioactivity. Their combination for the preparation of membranes is hereby proposed as an application for wound healing with the incorporation of lavender essential oil (LEO), widely known for its antioxidant and antimicrobial properties. The preparation of CHT, CHT + LEO, ALG, ALG + LEO, and CHT/ALG + LEO membranes was accomplished, and its composition was analyzed using Fourier Transform Infrared Spectroscopy (FTIR). The water absorption capacity and oil release profile of the membranes revealed higher water uptake capacity when a lower LEO release was obtained. The combined CHT/ALG + LEO film showed a water uptake percentage of 638% after 48 h and a maximum LEO release concentration of 42 mg/L. Cytotoxicity and biocompatibility of the prepared membranes were studied using a HaCaT cell line, with an assessment of cell viability regarding film leachables, DNA quantification, and DAPI-phalloidin staining. The results revealed that the indirect contact of the prepared membranes via its leachables does not compromise cell viability, and upon direct contact, cells do not adhere or proliferate on the surface of the membranes. Moreover, the CHT/ALG + LEO membrane increases cell proliferation, making it suitable for applications in wound healing. [ABSTRACT FROM AUTHOR]

Intranasal route, ensuring suitable bioavailability of medicines under circumvention of the gastrointestinal degradation and hepatic first-pass elimination, has been a popular choice for drug delivery. Among nasal dosage forms, mucoadhesive solid inserts have been shown to resist mucociliary clearance and provide a prolonged nasal residence time. Hence, the purpose of this study was the preparation and characterization of nasal inserts composing of polyelectrolyte complexes (PECs) based on k-carrageenan (k-CA) and chitosan (CS) to boost therapeutic efficacy of sumatriptan succinate in the treatment of migraine headache. k-CA/CS PECs were developed in different molar ratios, subjected to lyophilization in small inserts in the presence of sumatriptan succinate, and finally investigated for water uptake ability, mucoadhesive potential, and drug release profile. The formation of PEC between the two polymers was affirmed by Fourier transform infrared spectroscopy (FTIR). Based on the results, it was revealed that the polyanion/polycation molar ratio plays a critical role in modulating the characteristics of the inserts, and among all the formulations, the one comprising k-CA/CS PEC with molar ratio of (4:1), (k-CA/CS(4:1)), demonstrated the highest water uptake ability and mucoadhesive potential and provided a more controlled release of sumatriptan succinate. This study illustrates the potential of the lyophilized inserts based on the k-CA/CS PECs, especially k-CA/CS(4:1), for efficient delivery of sumatriptan succinate via the nasal route of administration and suggests a potential therapeutic approach for the termination of migraine attacks. [ABSTRACT FROM AUTHOR]

In order to enhance rice productivity under water-deficient conditions, it is essential to improve nitrogen (N) uptake ability or its use efficiency. The objectives of the present study were to examine the genotypic variation in N uptake ability and physiological N use efficiency (PNUE) among 70 rice cultivars, and to clarify its association with biomass production and water uptake ability. Plants were grown under three soil moisture regimes: flooded and two non-flooded (−0.10 and −0.52 MPa soil water potential) conditions. A substantial genotypic variation in the amount of aboveground N uptake was observed, and the amount bore a positive correlation with aboveground biomass production regardless of soil moisture regime, whereas PNUE showed a negative if any correlation with biomass production depending on soil moisture regime. A significant interactive effect on the amount of aboveground N uptake between cultivars and soil moisture regimes was observed; there existed cultivars that exhibited superior N uptake only under non-flooded conditions. N uptake ability was closely correlated with water uptake ability, while a substantial genotypic variation in N uptake per unit water uptake was found in the two non-flooded regimes. These results indicate that a substantial genotypic variation in N uptake ability under water deficient conditions exists among diverse rice genetic resources, and that the variation is associated with water uptake ability and biomass production under the water-limited conditions at the early growth stage.

Genetic improvement in water uptake ability and/or water use efficiency (WUE) of rice cultivars is one option to enhance productivity under water-limited conditions. We examined the genotypic variation in biomass production among 70 rice cultivars (69 cultivars of NIAS global rice core collection and Azucena) under different soil moisture conditions, and to identify whether water uptake ability or WUE is responsible for the variation, if any. Two-week-old seedlings were transplanted into pots and grown for three weeks in an environmentally-regulated growth chamber under three soil moisture regimes: flooded (−0.02 MPa soil water potential) and two unflooded (−0.10 and −0.52 MPa) conditions. Substantial genotypic variations in total dry weight (TDW) were observed under all three regimes. Among all the cultivars tested, TDW was significantly correlated with water uptake ability, but not with WUE. However, several cultivars exhibited comparably higher WUE while showing superior biomass production under the −0.52 MPa regime. The amount of water uptake was significantly correlated with root dry weight among cultivars regardless of moisture regimes, while substantial genotypic difference in the amount of water uptake per unit root dry weight was observed. These results indicate that a marked genotypic difference exists in biomass production at the early vegetative growth under water-deficient conditions, and that this difference appears to be ascribed primarily to greater water uptake capacity, and additionally to higher WUE in drought-tolerant cultivars.

Agro-hydrological models are considered an economic and simple tool for quantifying crop water requirements. In the last two decades, agro-hydrological physically based models have been developed to simulate mass and energy exchange processes in the soil-plant-atmosphere system. Although very reliable, because of the high number of required variables, simplified models have been proposed to quantify crop water consumes. The main aim of this paper is to propose an amendment of the Food and Agricultural Organization (FAO) of the United Nations FAO-56 spreadsheet program to introduce a more realistic shape of the stress function, valid for mature olive orchards ( Olea europaea L.). The modified model is successively validated by means of the comparison between measured and simulated soil water contents and actual transpiration fluxes. These outputs are finally compared with those obtained with the original version of the model. Experiments also allowed assessing the ability of simulated crop water stress coefficients to explain the actual water stress conditions evaluated on the basis of measured relative transpirations and midday stem water potentials. The results show that the modified model significantly improves the estimation of actual crop transpiration fluxes and soil water contents under soil water deficit conditions, according to the RMSEs associated with the revised model, resulting in significantly higher than the corresponding values obtained with the original version. [ABSTRACT FROM AUTHOR]