Removing Products of Thermal Degradation from Edible Oils by Zeolite and by Clinoptilolite - Comparison of Results

When edible oils are heated above 150°C, they undergo thermo-oxidative changes depending on a variety of factors, such as temperature, heating time, type of oil, etc. These changes cause a series of chemical reactions (hydrolysis, oxidation, polymerization, etc.) resulting in the formation of free fatty acids, an increase in the peroxide number and the acid number, a change of color and a decrease in the iodine number. This study investigates changes of the content of free fatty acids, the acid number, and the peroxide number in edible sunflower oil when heating at the temperature range from 110°C to 190°C for 30 minutes, as well as after the adsorption by a natural and a synthetic adsorbent (clinoptilolite and zeolite 4A). The results of the research show that these adsorbents are effective in removing the products of chemical reactions occurring in thermal degradation, which is particularly evident after the adsorption of oil heated at 190°C. Somewhat better results were achieved after the adsorption using clinoptilolite, with a 72 % reduction in the content of free fatty acids, 83 % reduction in the acid number, and 43 % reduction in the peroxide number. After the adsorption by zeolite 4A, the content of free fatty acids was reduced by 65%, the acid number by 76 %, and the peroxide number by 39 %. The results obtained open the possibilities of further research aiming at discovering the adsorbents which would be most suitable for the regeneration of used edible oils, after which they could be applied safely for different purposes. Keywords: edible oil, free fatty acids, acid number, peroxide number, adsorben

Electrical Conductivity of Lignocellulose Composites Loaded with Electrodeposited Copper Powders. Part III. Influence of Particle Morphology on Appearance of Electrical Conductive Layers

The electrical conductivity of the system based on lignocellulose (LC) biopolymer matrix filled with electrodeposited copper powder has been studied. Galvanostatically produced copper powder, having highly porous, highly dendritic particles with high values of specific area was used as filler. Volume fraction of the electrodeposited copper powder was varied from 2.0-29.8 vol%. Analysis of the most significant properties of prepared composites and its components included measurements of electrical conductivity, impedance spectroscopy (IS) behavior, structural and morphological analysis. The composite preparation conditions allowed the formation of a random distribution of metallic particles in the polymer matrix volume. It was shown that percolation threshold depends on both particle shape and type of spatial distribution. IS measurements have shown that particle morphology having pronounced grain boundaries has great effect on appearance of electric conductive layers, i.e.. movement. of percolation threshold towards lower filler volume fractions. IS response of the composites showed existence of electrical conductive layers, each having different resistivity which increases towards interior of the composite

Biodegradable Polymers Based on Proteins and Carbohydrates

Biodegradable polymers have become an import focus of interest in recent years. They include polymers manufactured from feedstocks originating either from non-renewable petroleum resources or from renewable biological resources. This review presents a general overview of biodegradable polymers, with a special emphasis on the polymers based on proteins and carbohydrates. Most biodegradable polymers (e.g., starch, chitin, cellulose, collagen and other polypeptides) have been synthesised or are formed in the natural environment during the growth cycles of organisms. These complex forms of carbohydrate consisting of glycosidic bonds are usually one of the major constituents of animal and vegetable exoskeletons (cellulose, carrageenan, chitin). Scientists have already identified certain microorganisms and enzymes that can degrade such polymers. Certain polymers draw attention to their biodegradability property. Bacteria, plants and animals produce this type of polymer, which presents the possibility for very momentous renewable resources. Some of the main plant proteins that can be used as potential sources are soy protein, corn protein (zein) and wheat proteins (gluten). Casein, collagen protein or gelatin, and keratin are important animal proteins. Environmental effects and chemical structure are the main factors upon which biodegradability depends. Another feature that depends on these factors is mechanical behaviour. Some other factors that impact mechanical behaviour are: processing parameters, storage, etc

SINTEZA KALCIJUM FERITNIH PEROVSKITA MIKROVALNO-POTPOMOGNUTOM DEKOMPOZICIJOM RAZLIČITIH PREKURSORA

Sinteza kalcijum feritnih pudera tipa perovskita je izvršena u kratkom vremenskom periodu putem dekompozicije karbonatnih i oksidnih prekursora korištenjem mikrovalne iradijacije (2.45 GHz, snage do 250 W). Na temperaturnim i energetskim dijagramima je kontinuirano bilježena apsorbovana, reflektirana i primjenjena snaga te temperatura uzorka. Karbonatni i oksidni prekursori su uspješno transformisani u kalcijum ferit. Početni materijali i produkti su karakterizirani difrakcijom X-zraka (XRD). Sinteza iz kalcijum oksida i magnetita se gledano po kristaliziranosti finalnog produkta pokazala uspješnijom. U poređenju sa dobro poznatim tradicionalnim putevima sinteze predstavljena metoda mikrovalno - potpomognute dekompozicije prekursora je brza, čista i energetski efikasna. Uz korištenje na mikrovalnu iradijaciju osjetljivih prekursora ovdje predstavljeni sintetski put zagrijavanjem mikrovalnm zračenjem može biti preporučen za proizvodnju kalcijum feritnih i drugih materijala tipa perovskita

Recording blood pressure and eGFR in primary care after the Belgrade screening study

Background: In 2009, Belgrade nephrologists and general practitioners from thirteen health centers carried out screening for chronic kidney disease (CKD). Three years later, medical records of patients from four health centers participating in the screening study were retrospectively analyzed in order to check whether general practitioners had continued to control patients at risk for CKD in accordance with the recommendations provided. Methods: The study included 460 patients who visited their doctor at least once in the three-year period. Data on blood pressure, ACEI use, estimated glomerular filtration rate (eGFR) and comorbidities were taken from patients’ medical records. Results: Blood pressure was not recorded in any of the three years in 42.8% and eGFR in 36.7% of the patients, but blood pressure was registered every year in 7.8% and eGFR in 4.3% of them. Over the three years, the relative number of patients with recorded blood pressure decreased from 41.7% to 17.8%, and with recorded eGFR from 41.7% to 21.5%. Multivariate linear regression found that Health Center, systolic and diastolic blood pressure and presence of hypertension were negatively associated with number of years with recorded blood pressure. Health Center, systolic blood pressure and sum of years with recorded eGFR below 60 ml/min/1.73m2 were associated with number of years with recorded eGFR. Conclusions: Under-recording of blood pressure and eGFR in primary care health centers suggests lack of adherence to current guidelines and insufficient care of CKD patients. This implies the necessity for continuous education of physicians