Sinteza, svojstva i primena umreženih makroporoznih kopolimera na bazi metakrilata

In this paper, the results obtained during extensive research on the synthesis, properties and application of cross linked copolymers, performed at the Faculty of Technology and Metallurgy (Department of Physical Chemistry and Electrochemistry) and at the IChTM (Center for Catalysis and Chemical Engineering and Center for Chemistry) are summarized. According to the obtained results, changes in the composition of the inert component and the content, type and amount of the crosslinking agent, as well as the type of copolymerization reaction, all strongly influence the porosity parameters of the synthesized macroporous copolymers. Also, it was shown that the synthesized copolymers of glycidyl methacrylate, GMA, and ethylene glycol dimethacrylate, EGDMA, modified with ethylene diamine can be used for the selective sorption of gold and platinum from mixed solutions containing copper, cobalt and nickel ions.U okviru ovoga rada prikazani su rezultati dobijeni u toku višegodišnjeg izučavanja sinteze, svojstava i primene makroporoznih umreženih kopolimera na bazi metakrilata, koja su obavljena pri Katedri za fizičku hemiju i elektrohemiju Tehnološko-metalurškog fakulteta u Beogradu, Centra za katalizu i hemijsko inženjerstvo i Centra za hemiju Instituta za hemiju, tehnologiju i metalurgiju u Beogradu. Pokazano je da se izmenom sastava i udela inertne komponente, vrste i udela umreživača, kao i načina izvođenja reakcije kopolimerizacije može bitno uticati na parametre porozne strukture sintetizovanih umreženih makroporoznih kopolimera i na taj način njihova svojstva prilagoditi različitim potrebama. Pokazano je takođe da se sintetizovani kopolimeri glicidilmetakrilata i etilenglikoldimetakrilata obrađeni sa etilendiaminom mogu uspešno koristiti za selektivno izdvajanje platine iz mešanih rastvora sa jonima bakra, kobalta i nikla

On the reproduction of yellow-necked field mouse (Apodemus flavicollis) and striped field mouse (A. agrarius) in laboratory conditions

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On the reproduction of yellow-necked field mouse (Apodemus flavicollis) and striped field mouse (A. agrarius) in laboratory conditions

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AGE STRUCTURE OF YELLOW-NECKED MOUSE (APODEMUS FLAVICOLLIS MELCHIOR, 1834) IN TWO SAMPLES OBTAINED FROM LIVE TRAPS AND OWL PELLETS

Abstract- The age structure of yellow-necked mouse (Apodemus flavicollis Melchior, 1834) has been analyzed in individuals obtained by two methods: trapping with Sherman live traps and obtainment of skulls from long-eared owl (Asio otus Linnaeus, 1758) pellets (predator diet analysis). One hundred and forty-four mice were analyzed for the degree of wear of the surface of molar crowns, and an additional 74 measurements were performed on captive-born Apodemus flavicollis individuals. We used a refined model of comparison that included seven classes of mouse age, rather than four classes, as suggested by other authors

Structure prediction, high pressure effect and properties investigation of superhard B6O

Ab initio data mining approach has been used in order to investigate B6O system and discover new possible modifications, besides experimentally known R-3m (alpha-B6O) structure and theoretically predicted Cmcm (beta-B6O) structure. DFT calculations were performed by two different functionals, LDA and PBE. In this work, we focus on the structure, mechanical, and electronic properties of the experimentally known alpha-B6O structure and newly predicted modifications with the B6O stoichiometry. Moreover, mechanical properties including elastic constants, bulk, shear and elastic moduli, Poisson's ratio, Pugh's criterion, and hardness are given for the investigated modifications of B6O. In particular, we have investigated the influence of the high pressure on the electronic and mechanical properties. Results of our study provide more insight in the B6O superhard material and open new possibilities for various device applications

Properties of activated alumina obtained by flash calcination of gibbsite

On exposing gibbsite, with granulation below 10 μm to flash calcination of 0.5 s in the regime of pneumatic transport and at temperatures above 883 K, a microcrystalline material with a high degree of amorphization was obtained, as established from data of XRD analysis. It was shown that at 883 K the mechanism of gibbsite dehydration changes with a decrease of the activation energy from 141 to 53 kJ/mol. The obtained activated alumina is characterized by a specific surface area of over 200 m2/g and a pore structure with micro- and mesopores developed in the inside of grains of the starting material

Metal sorption on macroporous poly(GMA-co-EGDMA) modified with ethylene diamine

Two samples of macroporous crosslinked poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate), poly(GMA-co-EGDMA), with different porosity parameters were synthesized by suspension copolymerization and modified by ring-opening reaction of the pendant epoxy groups with ethylene diamine (EDA). The samples were characterized by mercury porosimetry, FT-IR spectroscopy and elemental analysis. The sorption rate of the modified copolymer, poly(GMA-co-EGDMA)-en for Cu(II) ions determined under non-competitive conditions was relatively rapid, i.e. the maximum capacity was reached within 30 min. Batch sorption capacities for Cu(II), Fe(II), Mn(II), Cd(II), Zn(II), Pb(II), Cr(III) and Pt(IV) ions were determined under non-competitive conditions in the pH range 1.25-5.5 at room temperature. The maximum sorption capacities of poly(GMA-co-EGDMA)-en under non-competitive conditions were 1.30 mmol/g for Pt(IV) at pH 5.5, 1.10 mmol/g for Cu(II) at pH 5.5, 1.06 mmol/g for Pb(II) at pH 1.25 and 0.67 mmol/g for Cd(II) ions at pH 5.5. The selectivity of poly(GMA-co-EGDMA)-en towards Cu(II), Co(II), Ni(II), Pb(II) and Pt(IV) ions was investigated under competitive conditions. Poly(GMA-co-EGDMA)-en showed high selectivity for Pt(IV) over Cu(II), Co(II), Ni(II) and Pb(II) ions at pH 2.1. At pH 5.5, the metal sorption capacities of poly(GMA-co-EGDMA)-en decreased in the order: Cu(II) gt Co(II) gt Pt(IV) approximate to Ni(II) gt Pb(II). Regeneration of the Cu(II), Ni(H) and Pb(II) loaded poly(GMA-co-EGDMA)-en with 2 M HIS04 showed that the polymer can be reused in several sorption/desorption cycles

Estimation of the correlation between the retention of s-triazine derivatives and some molecular descriptors

In this study, 14 newly synthesized s-triazine derivatives were investigated by means of reversed-phase thin-layer chromatography (TLC) on C-18 stationary and two different mobile phases: acetonitrile-water and methanol-water. Quantitative structure-retention relationship (QSRR) was developed for a series of s-triazine compounds by the multiple linear regression (MLR) analysis. An MLR procedure was used to model the relation-ships between molecular descriptors and retention of s-triazine derivatives. Physico-chemical molecular descriptors were calculated from the optimized structures. Statistically significant and physically meaningful QSRRs were obtained

Validacija kratke međunarodne kognitivne procjene multiple skleroze u velikoj kohorti bolesnika s relapsno-remitentnom multiplom sklerozom

Cognitive impairment is one of the most frequently reported symptoms in persons with multiple sclerosis (MS). The Brief International Cognitive Assessment for Multiple Sclerosis (BICAMS) has been recommended as a standardized international screening and monitoring tool for brief cognitive assessment. The aim of our study was to assess the reliability and validity of the Serbian version of the BICAMS. A total of 500 relapsing-remitting MS (RRMS) patients and 69 age-, gender- and education- matched healthy control (HC) subjects were examined. All participants performed the BICAMS test battery, which includes the oral version of the Symbol Digit Modalities Test (SDMT), California Verbal Learning Test second edition (CVLT-II), and Brief Visuospatial Memory Test Revised (BVMTR). A randomly selected subset of patients were retested one to three weeks after baseline. Statistically significant differences between patients and HCs were evident on the SDMT and BVMTR (p<0.001). HCs had higher CVLT-II scores but this difference did not reach statistical significance (p=0.063). Cognitive impairment, defined as an abnormal test score on ≥1 subtest, was found in 62.9% of MS patients. There were statistically significant correlations between BICAMS scores and age, education, EDSS and disease duration in patient sample. Test-retest reliability was confirmed with Pearson correlation coefficient of 0.70 in all measures. This study supported the reliability and validity of the Serbian BICAMS, although the CVLT-II version tested here lacked sensitivity to detect MS compared to healthy volunteers.Kognitivno oštećenje je jedna od najčešće prijavljivanih manifestacija kod osoba s multiplom sklerozom (MS). Kratka međunarodna kognitivna procjena multiple skleroze (engl. Brief International Cognitive Assessment for Multiple Sclerosis, BICAMS) je baterija testova preporučena za brzu kognitivnu procjenu, koja je međunarodno standardizirana. Cilj našeg istraživanja bio je procijeniti pouzdanost i validnost srpske verzije BICAMS-a. Ispitano je ukupno 500 bolesnika s relapsnoremitentnom MS (RRMS) i 69 zdravih kontrolnih osoba (ZK) ujednačenih po uzrastu, spolu i razini obrazovanja. Svim sudionicima u studiji napravljen je BICAMS, koji uključuje usmenu verziju Testa analogije simbola i brojeva (SDMT), Kalifornijski test verbalnog učenja (CVLT-II), drugo izdanje i revidirani kratki test vizualne memorije (BVMTR). Nasumično odabrana podskupina bolesnika je ponovno testirana 1-3 tjedna nakon prvog testiranja. Statistički značajne razlike između bolesnika s MS i ZK zabilježene su za SDMT i BVMTR (p<0,001). ZK su imali viši zbroj CVLT-II, ali ova razlika nije dostigla statističku značajnost (p=0,063). Kognitivno oštećenje definirano kao nenormalni rezultat testa na ≥1 subtestu utvrđeno je kod 62,9% bolesnika s MS. Postojale su statistički značajne korelacije između rezultata testova BICAMS-a i dobi, razine obrazovanja, proširene ljestvice onesposobljenosti (EDSS) i dužine bolesti u skupini bolesnika s MS. Pouzdanost test-retest je potvrđena Pearsonovim koeficijentom korelacije od 0,70 u svim mjerenjima. Ova studija je pokazala pouzdanost i validnost srpskog BICAMS-a, iako verzija CVLT-II koja je ovdje testirana nije bila osjetljiva za otkrivanje kognitivnih poremećaja kod MS u usporedbi sa ZK

Strain differences in the humoral immune response to commensal bacterial antigens in rats

We have investigated the immune response to commensal bacterial species in the two inbred rat strains: Dark Agouti (DA) and Albino Oxford (AO). The predominant Gram-negative aerobe in our rats' intestinal bacterial flora was Escherichia coli, while Proteus mirabilis was isolated only from DA rat strain. We report that sera from both DA and AO rat strains contain specific IgG against predominant intestinal flora. Intramuscular administration of commensal bacterial antigens provoked only Th1-type antibody response in AO rats while DA rats developed mixed Th1- and Th2-type antibody response to E. coli and Th1-type response to P. mirabilis antigens. Weaker antibody production to own E. coli and higher serum levels of natural IgG and IgA P. mirabilis-specific antibodies combined with higher CD3+ cells proliferation was found in AO rats. Strain difference in the pattern of antibody production and differential regulation of immune response to commensal bacteria may contribute to the marked differences in the immune reactivity of AO and DA rats