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Abstract  

The determination of uranium by a fluorimetric method using a conventional spectrophotometer has been elaborated. The quenching effect of the matrix was reduced by separation with liquid-liquid extraction and emulsion liquid membrane extraction methods using D2EHPA as a selective extraction reagent. The method was employed for uranium determination in radioactive waste solutions and proved to be very fast and easy to perform. It was found that it is possible to determinate as low as 0.2 ppm of uranium in a 10 ml sample.

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Abstract  

Poly(AN—co—St) (PAS) and poly(AN—St—MMA)(PASM) were synthetized by emulsion polymerisation. The glass transition temperatures (T g) of the copolymers and the relationship between T g and the components of the copolymers were investigated by differential scanning calorimetry. The results show that T g for the AN—St bipolymers has apeak value in the range 115–118°C at a content of 50 mass% St. When methyl methacrylate was added, the T g of the terpolymer was decreased by about 2–6°C.The thermostability and the activation energy E of degradation were determined by thermogravimetric analysis.

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Abstract  

The studies on the application of the emulsions of poly(vinyl acetate-co-allyl ether)s containing nonionic hydrophilic poly(oxyethylene) fragments as binders in the die pressing of alumina is presented. It was found that introduction of hydrophilic fragments into molecules of a typical water dispersible polymer led to better polymer affinity to the ceramic powders. It was also shown that low molecular mass of such copolymers should be relatively low ca 1500 g mol–1 to increase the density and thickening uniformity of the samples before and after sintering. The resultant sinters indicated exceptionally high mechanical strength (bending strength ca 500 MPa).

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In present study, water extract of cornelian cherry (Cornus mas L.) (WECM) was studied for antioxidant properties. The antioxidant properties of WECM were evaluated using different antioxidant tests, including reducing power, free radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, and metal chelating activities. These properties may be the major reason for the inhibition of lipid peroxidation. The concentration of 20, 40 and 60 µg ml-1 of WECM showed 75.8, 93.4 and 97.5% inhibition on peroxidation of linoleic acid emulsion, respectively. On the other hand, 60 µg ml-1 of standard antioxidants such as BHA, BHT and a-tocopherol exhibited 96.5, 99.2 and 61.1% inhibition on peroxidation of linoleic acid emulsion, respectively. In addition, the WECM had effective reducing power, free radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, and metal chelating activities at the same concentrations (20, 40, and 60 µg ml-1). Those various antioxidant activities were compared to reference antioxidants such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and a -tocopherol. In addition, total phenolic compounds in the WECM were determinedas gallic acid equivalent.

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Abstract  

An experimental method was conducted to evaluate the minimum bubble nucleation energy of freon-12 for application in the superheated-liquid-droplet (SLD) technique. The minimum energy needed for an incident particle to cause the bubble nucleation is based on the theoretical calculation ofW min/ηkr c value. The calculated value may mislead the result of measured intensity due to its under/overestimation ofW min/ηkr c values at various temperatures. Nevertheless, the experimental evaluation ofW min/ηkr c of freon-12 for causing the bubble nucleation is barely touched because the proper methodology has not developed fully. The minimum energy needed to produce the bubble nucleation, can be evaluated by mixing the alpha-emitting nuclides with the SLD. By direct hitting the SLD with alpha-particle, the energy deposited inside the SLD may cause the bubble nucleation if the deposited energy is larger than theW min/ηkr c of freon-12 droplet at that specific temperature. The experimental evaluated values in this study agree with the theoretical estimation in 78% for SLD emulsion temperature within 22–34°C. Tests suggest that to apply the SLD in measuring the alpha-emitting nuclides, the emulsion temperature should be maintained below 30°C to get a maximum efficiency and to avoid interference from beta or gamma event.

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The insecticide formulation BI 58 EC was tested for teratogenicity in chicken embryos, with particular reference to degradation of the active ingredient (dimethoate) after the treatment of embryonated eggs. The pesticide was diluted in water to a concentration level of 0.8%, and the emulsion was injected into the air space in a volume of 0.1 ml/egg, or hen’s eggs were treated by the immersion technique. Residues of dimethoate were measured in the samples on days 13, 15 and 19 of the incubation of chicken embryos, and morphological examinations were performed simultaneously. Analytical chemistry data indicated a slower degradation of dimethoate in embryos after the immersion of eggs, and cyllosis was remarkable in this group among the sporadic developmental anomalies. The liver tissues ofboth treated groups exhibited severe fatty infiltration.

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Abstract  

A methodology for the isotopic determination of lithium in enriched7LiOH.2H2O samples by SSMS is described. The photoplate emulsion calibration curve was not used. The accuracy of the results was checked against the analysis of LiOH.2H2O with natural isotopic composition, and it was found that the result obtained was accurate within 5% with respect to the published natural value. The accuracy was improved using an enriched in7Li reference sample. The technique was applied to the analysis of batches of7LiOH.2H2O to be used in a nuclear power reactor to control the pH in the water cooling system.

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The aim of the present study was to test the antioxidant activity of rosemary extract and its mixture with propylene glycol on the stability of fat in butter. Rosemary extract was added at a concentration of 0.02% (w/w) and mixture of rosemary extract with propylene glycol at a concentration of 0.25% (w/w) to the cream before churning. For comparison, control samples without added antioxidant were also prepared and tested. Samples were stored at 4 °C and at 20 °C for 27 days and their peroxide values were determined periodically. The measurement of peroxide values for butter at 60 and 98 °C was also performed. Activity of rosemary extracts was compared with synthetic antioxidant BHT. The rosemary extract and its mixture with propylene glycol exhibited strong antioxidant activity in butter when added to a cream before churning and in an aqueous emulsion system of β-carotene and linolenic acid.

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Journal of Thermal Analysis and Calorimetry
Authors: Eszter Csizmazia, Mária Budai-Szűcs, István Erős, Zsolt Makai, Piroska Szabó-Révész, Gábor Varju, and Erzsébet Csányi

Abstract  

Our aim was to develop potential dermal drug delivery systems (DDSs) with a good and lasting moisturizing effect. Lyotropic liquid crystals (LLCs), gel-emulsions and hydrogels were investigated by means of thermogravimetry, which can give information about the structure of these preparations, and we could study the water binding mechanisms indirectly in them. We found that the preparations with a complex structure and strong water bonds hydrate the skin well and lastingly by in vivo tests. Since the thermoanalytical results correlate with the in vivo test results, this method could be suited for predicting the moisturizing effect of the vehicles and provide the possibility to select the potential semisolid DDSs for in vivo tests cost and time effectively.

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Summary Emulsifiers are often used in the food industry to stabilize interfaces in emulsions and foams, for example. When added to an aqueous phase, emulsifiers form spontaneously self-assembly structures. Such structured fluids can be used for active ingredients encapsulation or as micro-reactors for flavour formation. In the present paper we describe the potentialities of DSC, mainly micro-DSC, to study phase transitions of emulsifiers alone and with addition of water. The main role of the calorimetric techniques will probably be to precisely determine melting and crystallization zones, to inform about polymorphism and hysteresis due to undercooling, and especially to follow the effects of guest molecules on the weak liquid crystal transitions. Micro-DSC, when compared to other techniques, generally allows measurements over an extended temperature range.

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