The definition of antioxidants, given in 1995 by Halliwell and Gutteridge, stated that an antioxidant is “any substance that, when present at low concentrations compared with that of an oxidizable substrate, significantly delays or inhibits oxidation of that substrate” [1]. In 2007, Halliwell gave a more specific definition, stating that an antioxidant is “any substance that delays, prevents or removes oxidative damage to a target molecule” [2]. Oxidation reactions produce free radicals that can start multiple chain reactions that eventually cause damage or death to the cell. Antioxidants remove these free-radical intermediates by being oxidized themselves, and inhibit other oxidation reactions, thus stopping the harmful chain reactions. Such oxidative processes are dangerous for all living cells, especially those in proximity to sites where active oxygen is released by photosynthesis. Spontaneous oxidation causes food rancidity and spoilage of medicines. Furthermore, oxidative stress is an important part of many human diseases that can occur, inter alia, due to a lack of appropriate nutrition and exercise, air pollution, smoking, and more, leading to lethal diseases, such as cancer. Therefore, it is imperative to include antioxidants in our diets. Due to the fact that synthetically produced antioxidants are currently used in the food and pharmaceutical industries in order to prolong product shelf life, there is currently a strong trend to search for large, available, and efficient natural sources of antioxidants to replace the synthetic ones, thus minimizing damage to our cells

No abstract

No abstract

The main goal of this study is to functionalize SrO with carbon dots (C-dots) and to explore the composite as a catalyst for fatty acid methyl esters (FAME) production using Chlorella vulgaris as feedstock. C-dots are synthesized by sonicating polyethylene glycol followed by sonochemical modification of Sr­(NO3)2 (precursor for SrO) with C-dots. Sonication facilitates the adhesion of C-dots to the surface of Sr­(NO3)2. The resulting material is calcined in an inert environment to form a SrO–C-dot composite. The effect of functionalizing SrO with C-dots on the transesterification of the lipids in the alga with methanol is studied. The optimization of a one-stage process of conversion of the lipid fraction of microalga Chlorella vulgaris into FAME using direct transesterification under microwave irradiation is illustrated. A lipid conversion value of 45.5 wt % is achieved using the SrO–C-dot catalyst after 2.5 min of microwave (MW) irradiation. The catalyst displayed better activity than commercial SrO. Microwave irradiation accelerates the disruption of the microalgal cells and facilitates the release of lipid content into the reaction medium. The catalyst is characterized by a variety of physicochemical techniques. The FAME product obtained from the alga is quantified using 1H NMR spectroscopy. The new catalyst, namely, SrO–C-dot nanoparticles (NPs), yielded 97 wt % FAME from Chlorella vulgaris in 2.5 min of MW irradiation.

The Ten-a gene of Drosophila melanogaster encodes several alternative variants of a full length member of the Odz/Tenm protein family. A number of Ten-a mutants created by inexact excisions of a resident P-element insertion are embryonic lethal, but show no pair-rule phenotype. In contrast, these mutants, and deficiencies removing Ten-a, do enhance the segmentation phenotype of a weak allele of the paralog gene odz (or Ten-m) to the odz amorphic phenotype. Germ line clone derived Ten-a(-) embryos display a pair-rule phenotype which phenocopies that of odz. Post segmentation eye patterning phenotypes of Ten-a mutants establish it as a pleiotropic patterning co-partner of odz.