Partial molar volumes of methoxybenzenes in carbon tetrachloride

The partial molar volumesV° for a number of methoxybenzenes in carbon tetrachloride at 25°C have been determined. Results are in reasonable aggreement withV° values calculated by the addition of group increments to a covolume factor of 11.61 cm³-mol^?1, and subtraction of fixed amounts for structural features known to involve intramolecular overcrowding.     

Partial molar volumes of amino acid derivatives in water

The partial molar volumes at infinite dilution for a number of hydrochlorides and sodium salts of N-methyl derivatives of , -aminocarboxylic acids in water at 25°C are measured and related to their van der Waals volumes. Results indicate that 4.96±0.48 water molecules hydrate a betaine hydrochloride. Volumes of proton ionization and interaction terms are evaluated. Group contributions to the partial molar volumes are also reported.     

DSC studies of aromatic hydrocarbon picrates

Melting temperatures, enthalpies and entropies of fusion of a number of crystalline, charge-transfer complexes of aromatic hydrocarbons with 2,4,6-trinitrophenol (picric acid) have been measured, together with the corresponding data for some aromatic hydrocarbons themselves and for picric acid. The data suggest that for this, and for other nitro-aromatic acceptor molecules, enthalpies of fusion of charge-transfer complexes reflect the complexing ability of the electron acceptor, although the contribution of the charge-transfer interaction to the measured enthalpy is small.     

Extraction and analysis of phenolics in food

Phenolics are ubiquitous compounds found in all plants as their secondary metabolites. These include simple phenols, hydroxybenzoic acid and cinnamic acid derivatives, flavonoids, coumarines and tannins, among others. The extraction of phenolics from source materials is the first step involved in their analysis. While chemical methods are used for determination of total content of phenolics, chromatographic and spectrometric analyses are employed for identification and quantification of individual compounds present. This paper provides a summary of background information and methodologies used for the analysis of phenolics in foods and nutraceuticals.     

Chickpeas from a Chilean Region Affected by a Climate-Related Catastrophe: Effects of Water Stress on Grain Yield and Flavonoid Composition

The Valparaiso region in Chile was decreed a zone affected by catastrophe in 2019 as a consequence of one of the driest seasons of the last 50 years. In this study, three varieties (‘Alfa-INIA’, ‘California-INIA’, and one landrace, ‘Local Navidad’) of kabuli-type chickpea seeds produced in 2018 (control) and 2019 (climate-related catastrophe, hereafter named water stress) were evaluated for their grain yield. Furthermore, the flavonoid profile of both free and esterified phenolic extracts was determined using liquid chromatography-mass spectrometry, and the concentration of the main flavonoid, biochanin A, was determined using liquid chromatography with diode array detection. The grain yield was decreased by up to 25 times in 2019. The concentration of biochanin A was up to 3.2 times higher in samples from the second season (water stress). This study demonstrates that water stress induces biosynthesis of biochanin A. However, positive changes in the biochanin A concentration are overshadowed by negative changes in the grain yield. Therefore, water stress, which may be worsened by climate change in the upcoming years, may jeopardize both the production of chickpeas and the supply of biochanin A, a bioactive compound that can be used to produce dietary supplements and/or nutraceuticals.     

Vitamin C and Phenolic Antioxidants of Jua (Ziziphus joazeiro M.) Pulp: A Rich Underexplored Brazilian Source of Ellagic Acid Recovered by Aqueous Ultrasound-Assisted Extraction

Jua (juá in Portuguese) is an underexplored fruit from Brazil’s northeast. This fruit is rich in antioxidant substances. However, there is a dearth of information about jua’s bioactive potential. The present study evaluated two extraction methods (continuous agitation and ultrasound-assisted extraction—UAE) and employed three different solvents (water, ethanol, and acetone) to efficiently recover soluble phenolic compounds. Aqueous extracts obtained by UAE showed the highest total phenolic content (TPC) and antiradical activity. Besides being an eco-friendly procedure, extraction and/or solubility in an aqueous medium is also important for food application. Ellagic acids were the predominant phenolics (80%) found in aqueous jua pulp extract obtained by UAE, as determined by HPLC, while its TPC was 405.8 gallic acid equivalent per gram of fruit. This extract also exhibited a higher scavenging activity towards peroxyl radicals when compared to that of several other fruits from the literature, including grape, strawberry, cranberry, and walnuts, which are known references in terms of antioxidants. This is the first report that demonstrates jua pulp’s potential as an alternative source of ellagic acid and other phenolic acids and flavonoids. Therefore, the outcome of this study provides new information that can be useful for functional food and nutraceutical industries.     

Partial molar volumes of organic compounds in water. VI. α,ω-diaminoalkane hydrochlorides

Measurements of the partial molar volumes in water at 25°C of the mono-and dihydrochlorides of the ,-diaminoalkanes, up to a chain length of 10 carbon atoms, are reported. Volumes of ionization have been determined and the electrostriction of the solvent calculated. Effects of the substituents are felt up to the -carbon atom, but thereafter are only very weak or nonexistent.     

Investigation of metal absorption and antibacterial activity on cotton fabric modified by low temperature plasma

In this work, the silver particle absorption and antibacterial activity of cotton fabric when modified by low temperature plasma were investigated. The modification consisted of plasma pre-functionalization followed by one-step wet treatment with silver nitrate solution. Oxygen and nitrogen were used as the working gases in the system, and the results were compared. The results showed that nitrogen plasma-treated samples can absorb more silver particles than oxygen-treated samples, and thus the antibacterial activity of the samples in this case, which was analyzed by the counting bacteria test, was increased considerably.     

Vibration analysis of nanorings using nonlocal continuum mechanics and shear deformable ring theory

In this article, we use shear deformable ring theory (SDRT) for the analysis of free in-plane vibration of nanorings based on nonlocal elasticity theory. The equations of motion of the nanoring are derived for the aforementioned problem by considering the small scale effect. Analytical solutions for the natural frequencies of the nanorings are presented. It is shown that the nonlocal effects play an important role in the vibration of nanorings and cannot be neglected. The effects of the small scale on the natural frequencies considering various parameters such as the radius of the nanoring, the thickness of the nanoring and mode numbers are investigated.