Synthesis and characterization of a titanium phosphate-tellurite glass for Faraday rotators

This work is focused on investigation of thermal, structural, optical, magnetic, and magneto-optical properties of novel titanium phosphate-tellurite glass applied as Faraday rotators. The glass belonging to the system 35Li₂O–10Al₂O₃–5TiO₂–45P₂O₅–5TeO₂ was prepared by a nonconventional wet route of raw materials processing, followed by melting-quenching-annealing steps. Some important physical properties of the investigated glass have been measured and calculated, providing knowledge related to glass compactness, electronic structure, glass forming capability, etc. XRD analysis evidenced an amorphous network structure of the investigated glass. The optical absorption in the Vis domain is mainly due to Ti³⁺ ions and Te₂ clusters formed during the glass melting process. A relatively low optical absorption is noticed over 600 nm that activates a significant Faraday magneto-optical effect. Photoluminescence bands in the blue, red, and infrared domains are observed, caused by Te₂ clusters formed during the glass melting process. The magnetization in dependency on applied magnetic field reveals a complex behavior of the glass, depending on temperature. Thus, it is found a ferromagnetic behavior up to 2000 Oe, a paramagnetic component up to 40 000 Oe, followed by a diamagnetic one over 40 000 Oe. Faraday rotation angle and Verdet constant values in the visible domain are correlated with the reduced TeO₂ content of the glass.     

Characterization of proteins and fibroblasts on thin inorganic films

The ability of biomaterial surfaces to regulate cell behavior requires control over surface chemistry and material microstructure. One of the goals in the development of silicon-based biomedical devices such as biosensors or drug delivery systems is improved biocompatibility which may be achieved through the deposition or adsorption of thin films. In this study, films of single crystal silicon, stoichiometric and low stress silicon nitride, doped and undoped polysilicon, as well as Arg-Gly-Asp (RGD) peptide adsorbed surfaces characterized in terms of protein adsorption or cellular adhesion for a period of four days. Protein adsorption studies using fibrinogen and albumin, two proteins implicated in cellular adhesion and surface activity, reveal that low stress silicon nitride surfaces have a 223%±2.50% greater protein adsorption compared to undoped polysilicon surfaces, followed by silicon nitride, unmodified silicon, and doped polysilicon surfaces, respectively. The thickness of the adsorbed albumin and fibrinogen layer on various thin films was measured by ellipsometry and compared to contact angle measurements. The greatest cellular adhesion was observed on undoped polysilicon, followed by unmodified (control) silicon, low stress silicon nitride, silicon nitride, and doped polysilicon surfaces. Cellular binding supports the differential protein adsorption found on modified and unmodified silicon surfaces. Understanding the biological response to thin films will allow us to design more appropriate interfaces for implantable diagnostic and therapeutic silicon-based microdevices.     

High performance size exclusion chromatography of fatty acids,mono-, di- and triglyceride mixtures

A high performance size exclusion chromatographic (HPSEC) method is described for the separation and quantitation of fatty acids, mono-, di- and triglyceride mixtures. The various lipid components were separated on two columns packed with 5 μm styrene/divinylbenzene copolymer and connected in series. Toluene was employed as eluant, and components were monitored by refractometry. A formula derived for calculation of total weighted correction factors (WCF) for the various lipid classes based on known values of correction factors of simple lipid components and the fatty acid composition of the sample allowed quantitation of lipid mixtures containing a variety of different molecules. The precision of the experiments is such that the relative standard deviation for each lipid component was 1–5%, and a component could be detected at 0.05% level.     

Eliciting the Sensory Modalities of Fat Reformulated Yoghurt Ice Cream Using Oligosaccharides

In the present work, fat reduction of Greek strained yoghurt ice cream (YIC) was carried out in three proportional milkfat levels i.e. 30, 50 and 70% using three types of oligosaccharides namely long-chain inulin, oligofructose and maltodextrin 12 DE. Greek strained yoghurt was blended with ice cream mixes in ratios of 1:3 and 1:1. The physico-chemical, textural and thermal characteristics of the YIC mixes and their obtained frozen end products were determined. The sensory modalities (olfactory, gustatory, tactile and oro-tactile) of the YIC were monitored following 2 and 16 weeks of quiescent frozen storage at ?25 °C. Milkfat reduction impaired significantly (p?<?0.05) the perceived creaminess and mouthcoating sensation stimuli, whist it intensified the oral tissue friction associated sense stimuli such as astringency, wateriness and coarseness. Long-chain inulin- and maltodextrin-based samples received the highest scores for creaminess, mouthcoating, gumminess, hardness and iciness. The increase of the yoghurt to ice cream mix ratio escalated the friction/recrystallization-associated sensations e.g. astringency, sourness, coarseness and wateriness. Notwithstanding yoghurt supplementation reinforced the pseudoplasticity and macroviscosity of the ice cream mixes, it suppressed their aeration capacity leading to heavy-bodied ice creams. However, no significant effects of yoghurt supplementation level on the colligative and meltdown rate of the YIC formulations were identified. Partial least squares coupled discriminant analysis (PLS-DA) revealed that fat reformulation of YICs using oligosaccharides results in a substantially diversified sensory profile. Generally, a 50% fat reduction of YICs using long-chain oligosaccharides appears to be a technologically tangible solution.     

Freeze-Dried Fennel Oleoresin Products Formed by Biopolymers: Storage Stability and Characterization

In this work, fennel oleoresin (FO) was encapsulated through freeze drying of the so produced emulsions within different edible biopolymeric carriers. Specifically, modified starch, maltodextrin, chitosan, and gum arabic were used as carriers both individually and in blends (binary and ternary ones). The freeze-dried FO products were characterized in terms of structure (X-ray diffraction (XRD) analysis), whereas their stability was studied by means of sorption isotherm analysis under various a _w. Moreover, the formation of complexes was evaluated through Fourier transform infrared spectroscopy (FTIR) technique and ζ-potential analysis. The verification of the encapsulation process was also conducted by applying FTIR technique. Results showed that the final products presented an amorphous character, whereas the sorption isotherms could be described adequately by the Guggenheim-Anderson-de Boer (GAB) model. FTIR technique proved to be effective to confirm both the formation of complexes and the presence of FO into the studied carriers, verifying thus the success of the process.     

Hazard analysis and critical control point of frying – safety assurance of fried foods

Deep frying can pose hazards due to oil deterioration (oxidation, polymerization, hydrolysis) and harmful components formation such as trans fatty acids, highly oxidized or polymerized constituents of fatty acids and acrylamide. An analysis of safety hazards of the production of the potato chips and french fries, was carried out from potato harvesting until final products packaging according to hazard analysis and critical control point approach focusing mainly on the first three principles. Since frying is considered a critical control point, the critical limits for the frying temperature and for the potential hazards must be controlled in order to ensure fried products safety.     

Spray Drying of Raisin Juice Concentrate

Raisin juice concentrate is a natural sweetener in syrup or paste form and it is produced from second-grade dry raisins by leaching them with water. Dried raisin juice, although is easier to handle and has more potential applications than the syrup, is not available in the market. In the present study, raisin juice powder was produced with a lab-scale spray dryer. The problem of stickiness in the drying chamber was overcome through the use of 21 DE, 12 DE, and 6 DE maltodextrins as drying aid agents. For each type of maltodextrin, the dryer operating conditions and the minimum concentration of maltodextrin in the feed, necessary for successful powder production, were determined. The maximum ratio of (raisin juice solids)/(maltodextrin solids) achieved was 67/33 and was made possible with the use of 6 DE maltodextrin. The inlet and outlet drying air temperatures were 110 and 77°C respectively, while the feed contained 40% w/w total solids. The physical and sensory properties of all powders produced were determined and found to be satisfactory, the only exception being their high hygroscopicity.     

A model process for the solvent recycling of polystyrene

A model solvent technique is presented according to which polystyrene (PS) foam scrap is recovered in the form of small grains. The process mainly comprises dissolution of the waste into benzene or toluene, filtering, dispersion of the solution into water, and subsequent distillation. The alternative solvent/non-solvent systems have been studied on the basis of solution rheology, operating conditions during the recycling procedure, and extents of recovery of PS and solvent. Eventually, the toluene/water system has been chosen for a larger scale experiment (LSE), the product of which was used for characterization work. No influence on critical properties was detected due to the solvent technique followed.