No abstract

Beetroot (Beta vulgaris L.) represents a very rich source of bioactive compounds such as phenolic compounds and carotenoids, among which the most important being betalains, mainly betacyanins and betaxanthins. The beetroot matrix was used in a fresh or dried form or as lyophilized powder. A 1012 CFU/g inoculum of Lactobacillus plantarum MIUG BL3 culture was sprayed on the vegetal tissue. The lactic acid bacteria (LAB) viability for all the products was evaluated over 21 days, by microbiological culture methods. The antioxidant activity of the obtained food products was correlated to the betalains content and the viability of LAB. The content of polyphenolic compounds varied between 225.7 and 1314.7 mg L−1, hence revealing a high content of bioactive compounds. Through the confocal laser scanning microscopy analysis, a large number of viable probiotic cells were observed in all the variants but especially in the fresh red beet cubes. After 21 days of refrigeration, the high content of Lb. plantarum (CFU per gram) of the food products was attributed to the biocompounds and the nutrients of the vegetal matrix that somehow protected the bacterial cells, and thus maintained their viability. The obtained food products enriched with probiotic LAB can be regarded as new functional food products due to the beneficial properties they possessed throughout the undertaken experiments.

The aim of this study was to improve the bovine colostrum biological function through fermentation with kefir grains enhanced with selected yeasts, for developing new nutraceutical and cosmeceutical products. It was found that fermentations with coculture of 2.5 g% artisanal kefir grains and selected yeast strains (10 6 CFU/100 mL) increased the functional quality of the fermented products compared to the product obtained only with kefir grains. Fresh fermented products obtained with a consortium based on kefir grains and Candida lipolytica MIUG D67 demonstrated an increased antioxidant activity of 2.69 mM Trolox Equivalent/g, after 48 h of fermentation. Instead, peptide fractions with MW<10 kDa isolated by membrane filtration from lyophilized fermented products, based on colostrum fermentation with kefir grains enhanced with Candida lipolytica MIUG D99 starter, presented markedly increase in vitro of ABTS radical scavenging activity, similar to a concentration of 2 nM captopril. These results indicated their possible application in enhance of the quality of the fermented products in order to increase the postbiotic composition with functional impact in vivo.

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This paper investigates in situ remineralization of the acid-etched natural enamel surface, by incubation in a phosphate solution with neutral pH, at 37 �C for 4-10 days, without using any enamel matrix derivative (EMD). We investigated the morphology, crystallinity, chemical composition and structure of the newly grown layer onto the natural enamel surface stored in contact with artificial saliva (AS) having a composition similar to natural oral environment. The crystalline phases, crystallite size and orientation, as well as the chemical and phase composition of the remineralized dental enamel samples were studied by scanning electron microscopy coupled with energy dispersive X-ray spectrometry, Fourier transform infrared spectroscopy and X-ray diffraction. The experimental results showed that the enamel crystals grown on the demineralized enamel surface are mainly Ca-deficient apatite hexagonal structure. Fluoridated hydroxyapatite and sylvite-type KCl crystallites, which amount considerable increased in the case of sample stored in AS for 10 days, were also identified.

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Dry sliding friction and wear behavior of single-wall (SW) and multi-wall (MW) carbon nanotubes (CNTs)/ vinylester composite have been investigated, under several loads and sliding speeds. Three different contents (0.1, 0.15 and 0.2 wt. %) of SWCNT and MWCNTs have been dispersed into the vinylester resin in order to obtain polymer nanocomposites. The present study discusses the coefficient of friction, specific wear rate and friction stability of vinylester composites with different CNTs content, using a pin-on-disc test. The friction and wear experiments were carried out following 3 loads�3 speeds, as test parameters. The best combination of friction and wear properties was found with the nanocomposite containing 0.2 wt.% MWCNT.

The Instrumented Indentation Technique (IIT) is used to measure the local mechanical properties of different materials. The mechanical parameters (indentation hardness and modulus) of multi-walled carbon nanotubes filled polypropylene (PP/MWCNTs) nanocomposites derived from the load-displacement indentation curve are investigated by sharp indentation. The effect of the visco-elastic-plastic deformations on the mechanical properties is studied considering a 5-step indentation test. The mechanical properties calculated based on the traditional Oliver and Pharr method are compared with those extracted from the new indentation methodology. During the 5-step indentation test, the viscoelastic deformations during the reloading-holding phases are reduced due to the decrease in the indentation displacement with the increase in the concentration.