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Abstract  

Composites of poly(vinyl pyrrolidone)/hydroxyapatite (PVP/HA), at variable proportions (100/0; 80/20; 50/50; 20/80 wt%) were prepared and characterized by Fourier transformer-infrared spectroscopy (FT-IR), wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), and thermogravimetry/differential thermogravimetry (TG/DTG). PVP carbonyl stretching was slightly shifted to lower frequency in composites indicating the formation of hydrogen bonding with HA hydroxyl groups. At the first cycle of heating, the calorimetric curves revealed a broad peak the intensity of which was reduced insofar as the amount of PVP decreased in the composites. This peak was attributed to the PVP enthalpy relaxation. According to the TG/DTG curves, PVP degraded into two steps sharply perceivable in the composites. The first decay was ascribed to the release of the pyrrolidone pendant groups and the following one concerned the burning of the hydrocarbon chains. The HA molecules seem to exert a catalytic action on the PVP degradation.

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Acta Alimentaria
Authors: J.M. Garcia, S. M. Castro, R. Casquete, J. Silva, R. Queirós, J.A. Saraiva, and P. Teixeira

pressure on growth and bacteriocin production of Pediococcus acidilactici HA-6111-2 . High Pressure Res., , 35 , 405 – 418 . Dicks , L.M. , Mellett

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Abstract  

Effects of pH, Eu(III) concentration, ionic strength, temperature and humic acid (HA) on Eu(III) sorption to iron oxides were investigated in detail. The sorption of Eu(III) to iron oxides was significantly dependent on pH and weakly dependent on ionic strength, and higher temperature was gainful to Eu(III) sorption. In the presence of HA, Eu(III) sorption was enhanced significantly at low pH; whilst obvious negative effect was observed in higher pH range. Below 12 mg/L HA, HA could obviously enhanced Eu(III) sorption to iron oxides, nevertheless Eu(III) sorption decreased steeply with increasing HA while HA exceeded 12 mg/L. The results were helpful for understanding radionuclides behaviors in natural environment.

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Abstract  

Radiolytic depolymerization of hyaluronic acid (HA, a heteropolysaccharide) in aqueous solutions under a variety of conditions demonstrates that the damaging effect of radiolytic radical species is in the following order
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$OH \cdot > e_{\bar aq} > O_2^{\bar .}$$ \end{document}
. Cysteine, penicillamine and dithiothreitol have been found to protect against primary radiolytic species. Our results point out that the enzyme superoxide dismutase (SOD) and the above three thiols do not protect against the radiolytic species generated by the
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anion and hyaluronic acid is faster than the reaction between
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and hyaluronic acid and that
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anions are not scavenged by superoxide dismutase. The results further suggest that t-butanol radicals interact with hyaluronic acid and reduce the viscosity of HA solutions. Preliminary pulse radiolysis experiments do demonstrate a reaction between
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dical and hyaluronic acid.
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Abstract  

The complexation of technetium with humic acid is usually done by a reduction of pertechnetate by Sn2+ ions. A Tc-HA complex can be scavenged in a Sn-HA complex, if tin is present as reductant. The main aim of the study was a preparation of the Tc-HA complex without impurities of Sn ions or other metal reductant, which was performed by a ligand exchange with hexakis(thiourea-S)technetium(III) under nitrogen atmosphere at pH 5.5. The [Tc(tu)6]3+ complex was prepared from TcO4 - in acidic solution with thiourea as a reductant. Presence of the Tc-HA complex and other technetium species was determined by gel chromatography, paper chromatography and dialysis. Yield of Tc-HA complex was about 80% and reaction mixture contains about 20% of technetium dioxide, which is a side product of ligand-exchange.

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Ha elvész a bizalom

When Trust Is Lost: Student Distrust and Academic Failure

Educatio
Author: Gabriella Pusztai

Absztrakt:

A hallgatói bizalom nemcsak az individuumszintű hallgatói jóllét egyik erős tartópillére, hanem – mivel a bizalom és a megbízható magatartás szoros összefüggésben áll egymással – jelentős társadalmi tény, s egyben előrejelzés a következő felnőtt állampolgári generáció társadalmi magatartására vonatkozólag. Tanulmányunkban egyrészt azt vizsgáljuk, hogy milyen törésvonalak mentén rendeződik el a bizalom napjaink hallgatótársadalmában, milyen hatással van a felsőoktatási hallgatók teljesítményére, milyen forrásból ered, valamint arra keressük a választ, hogy a lemorzsolódásban milyen szerepe lehet a bizalomvesztésnek. Három adatbázis adatait elemeztük Magyar Ifjúság 2016, A hallgatói eredményességre gyakorolt intézményi hatás (IESA 2015) és a Lemorzsolódottak (Depart 2018). Az elemzés során azt tapasztaltuk, hogy az országos hallgatói adatok szerint a közintézményekbe vetett bizalom szintje a szülői iskolázottsággal meghatározott státus mentén jelentős eltéréseket mutat, az egyenlőtlenségeket tovább színezik a vallásosság szerinti különbségek. A kelet-magyarországi intézmények hallgatói között azonban egyenletesen magas a bizalmatlanok aránya. A felsőoktatási tanulmányi kudarcot szenvedők bizalomszintje alacsony, a lemorzsolódottak a bizalom megroppanásával magyarázzák tanulmányaik félbehagyását. Noha a nevelési-oktatási hatékonyság alapfeltétele lenne a szereppartnerek közötti bizalomteljes kapcsolat, a tömegessé, majd üzletiessé vált felsőoktatásban a hallgatók domináns élménye az oktatói odafigyelés nélkülözése és a személytelenség.

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Abstract  

The sorption of Eu(III) on calcareous soil as a function of pH, humic acid (HA), temperature and foreign ions was investigated under ambient conditions. Eu(III) sorption on soil was strongly pH dependent in the observed pH range. The effect of ionic strength was significant at pH < 7, and not obvious at pH > 8. The type of salt cation used had no visible influence on Eu(III) uptake on soil, however at low pH values, the influence of anions was following the order: Cl ≈ NO3  > ClO4 . In the presence of HA, the sorption edge obviously shifted about two pH units to the lower pH, whilst in range of pH 6–7, the sorption of Eu(III) decreased with increasing pH because a considerable amount of Eu(III) was present as humate complexes in aqueous phase, then increased again at pH > 11. The results indicated that the sorption of Eu(III) on soil mainly formed outer-sphere complexes and/or ion exchange below pH ~7; whereas inner-sphere complexes and precipitation of Eu(OH)3(s) may play main role above pH ~8.

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Several plant-originated natural compounds were shown to exhibit chemopreventive effect in carcinogenesis. In our studies, we have investigated CoD™ extract, a complex plant extract made from several tropical plants with possible cancer preventive effect in animal experiments. c-myc, p53 and Ha-ras gene expressions were investigated 24, 48 and 72 h after CoD™ extract and dimethylbenz(a)-anthracene (DMBA) treatment in CBA/Ca(H-2 K ) mice. CoD™ extract administered together with DMBA diminished c-myc, p53 and Ha-ras gene expressions both in the 24 and 48 h experiments, but not in the 72 h experiments. Further in vivo and human studies are needed to clarify the possible role of CoD™ extract in the prevention of tumour formation after carcinogenic exposures.

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„Hiszen én, ha azt mondom tej...”, avagy barkácsolás az oktatásban

After All, If I Say Milk... or Gadgeteering in Education

Educatio
Author: Ildikó Csikai
Open access

Comparison of the Ukrainians and Russians, comparison of their scale of values is one of the main motives, which comes up again and again in the Ukrainian literary pieces of 19th century. Comparison of two nations reflects the extremely complicated his-torical, political and economical situation of their coexistence and is made on political, economical, national, cultural, psychological and linguistical levels. Sly Moscal is usually depicted from the point of view of disposed and decent Ukrainian peasant, who is compelled to struggle for his history, tradition, culture and language, compelled to prove sovereignty of the Ukrainian nation. Moscal in G. Kvitka-Osnovjanenko's comedy "Svatannja na Gonča-rivcy" is represented, on one hand, in general, and, on the other hand, in the character of Osip Skorik, the discharged soldier.

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