Polymer based nanocomposites

Dispersions consisting of spherical CdS and α-Fe2O3 particles in the nanometer and sub-micron size range, as well as β-FeOOH nanorods with three different aspect ratios were prepared using colloidal chemistry methods. After incorporation of filler particles into polystyrene and poly(methyl methacrylate) matrices influence of filler particles on the thermal stability and the glass transition temperature of polymer matrices was studied in details. Significant influence of content, size and shape of filler particles on thermal properties of polymer matrices was found.Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200

Surface modification of TiO2 nanoparticles with catechol

Surface modification of nanocrystalline TiO2 particles with catechol was found to result in a red shift of the semiconductor absorption compared to unmodified nanocrystallites. The undercoordinated defect sites at TiO2 surface are the source of novel enhanced and selective reactivity of the nanoparticle toward bidentate ligand binding. Catechol, an enediol ligand, have the optimal geometry for chelating surface Ti atoms, resulting in a five-membered ring coordination complex and restoration of six-coordinated octahedral geometry of surface Ti atoms.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Thermal properties of nanocomposite film consisting of PVA and shaped Ag nanoparticles

Manipulation of the size and shape of metal nanoparticles has attracted a great deal of attention recently and opened-up possibility for their usage in various fields such as microelectronics and optics. Prismatic and plate-like silver nanoparticles synthesized in water by colloidal chemistry methods, were used as a precursor for preparation of transparent and colored Ag/PVA nanocomposite films. Due to structural anisotropy of prismatic and plate-like silver nanoparticles, confirmed by TEM measurements, in absorption spectrum were observed three surface plasmon resonance bands. In absorption spectrum of Ag/PVA nanocomposite film appears only one absorption band. Interaction between Ag nanoparticles and PVA matrix was followed using FTIR spectroscopy. The thermal properties of Ag/PVA nanocomposite film has been examined using TGA and DSC techniques. The thermal decomposition of the PVA matrix in the presence of shaped Ag nanoparticles is shifted towards higher temperatures for about 14o C in argon atmosphere. Slightly higher thermal stability was obtained during thermo-oxidative degradation process. DSC measurements revealed that shaped Ag nanoparticles incorporated in PVA matrix do not have significant influence on the crystallization temperature changes

Optical properties of Au nanorods/PVA nanocomposite films

Polymer based nanocomposites have emerged as a new class of materials and attracted considerable interest due to their new or much improved optical, electrical and thermal properties. Au nanorods are synthesized in water using seed-mediated growth method in the present of surfactant CTAB and silver ions. The size and shape of Au nanorods (length-width aspect ratio 4) were examined by TEM technique. Colloidal solution of Au nanorods was used as a precursor for synthesis of Au/PVA nanocomposite films. The optical properties of transparent and colored nanocomposite films were evaluated by UV/ViS absorption spectroscopy. The appearance of two surface plasmon resonance bands in absorption spectrum of Au nanorods colloidal solution is consequence of structural anisotropy. Different dielectric properties of PVA polymer compared to water environment induced position changing of the longitudinal and transversal plasmon resonance bands in absorption spectrum of Au nanorods/PVA nanocomposite films

Theoretical and experimental analysis of droplet-to-particle formation during aerosol processing of colloidal TiO2 nanoparticles

Theoretical and experimental investigation of the particle formation during processing of colloidal nanoparticles in aerosol laminar flow reactor is presented. Simple analytical model taking into consideration all important process parameters, such as physico-chemical properties of the colloidal solution, initial droplet size, residence time and temperature, is developed in order to predict the final particle morphology. The formation of spherical, hierarchically organized, ~450 nm sized TiO2 particles has been followed at 150°C starting from colloidal TiO2 nanoparticle (~4.5 nm) solution as precursor. It has been shown that the final particle morphology is formed in the evaporation/drying stage through the self assembly processes of colloidal nanoparticles collision and aggregation. The dimensionless numbers Re, Nu, Pr and Bi, were used in modeling to briefly describe the transport properties in dispersed system and heat and mass transport phenomena. The predicted particle size and morphology is confirmed by using scanning electron microscopy (SEM/FESEM) and laser diffraction particle size analyzer (LPS). Additionally, closer morphological investigation is performed with transmission electron microscopy (TEM) and nanotomography. Correspondingly, theoretical analysis under this study presents a simple procedure to predict the final morphology and mean particle size during aerosol processing

Epidemija pandemijskog gripa H1N1 u Vojnoj gimnaziji

Background/Aim. The first cases of the pandemic pH1N1 influenza virus infection was observed in the United States and Mexico in April 2009 and the first laboratory confirmed case in Serbia was registered in June 2009. The aim of this paper was to report on the investigation of the first confirmed outbreak of the 2009 pandemic H1N1 influenza in Serbia and to describe the clinical and epidemiologic findings from this investigation. Methods. Descriptive and analytical epidemiological methods were used. Data were collected from medical records of the Military School students and epidemiological questionnaire. Pandemic H1N1 infection was initially confirmed by the RT-PCR assay in nasopharyngeal and oropharyngeal swabs and subsequently by the complement fixation test in serum samples. Results. The attack rate of acute respiratory illness was 70.8% (204/288). Pandemic H1N1 virus infection was confirmed in 44 of 82 tested cases of acute respiratory illness (53.7%) The most common clinical manifestations of pandemic influenza H1N1 were fever (88.6%), cough (61.4%), malaise (38.6%), runny nose (36.4%), headache (29.6%), sore throat (20.5%) and muscle pain (15.9%). Conclusion. The findings from this investigation suggest that pandemic H1N1 influenza in a high military school was widespread but did not cause severe illness.Uvod/Cilj. Prvi slučajevi pandemijske infekcije virusom influence pH1N1 ustanovljeni su u Americi i Meksiku u aprilu 2009. a u Srbiji prvi laboratorijski potvrđen slučaj registrovan je u junu 2009. godine. Cilj rada bio je da se prikaže istraživanje prve dokazane epidemije pandemijske influence H1N1 u Srbiji i opišu klinički i epidemiološki nalazi iz ovog istraživanja. Metode. Primenjen je deskriptivni i analitički epidemiološki metod. Izvor podataka bila je medicinska dokumentacija učenika Vojne gimnazije i epidemiološki upitnik. Infekcija pandemijskim virusom H1N1 prvo je dokazana pomoću RT-PCR u nazofaringealnim i orofaringealnim brisevima, a zatim i reakcijom vezivanja komlementa u uzorcima seruma. Rezultati. Stopa javljanja akutnog respiratornog oboljenja iznosila je 70.8% (204/288). Infekcija pandemijskim H1N1 virusom potvrđena je kod 44 od 82 testiranih slučajeva akutnog respiratornog oboljenja (53,7%). Najčešće kliničke manifestacije pandemijske influence H1N1 bile su povišena temperatura (88,6%), kašalj (61,4%), malaksalost (38,6%), rinitis (36,4%), glavobolja (29,6%), gušobolja (20,5%) i bol u mišićima (15,9%). Zaključak. Rezultati ovog istraživanja ukazuju da je pandemijska influenca H1N1 bila raširena u Vojnoj gimnaziji, ali da nije izazvala teške forme oboljenja

Two-phase boundary synthesis and optical properties of silver/polyaniline nanocomposites

Nanocomposites containing metal nanoparticles, dispersed in electrically conducting polymers such as polyaniline, show enhanced sensing, electrical and catalytic properties as compared with those of neat polymer. These composites have generated increasing interest as advanced technological materials due to synergistic effects of both components. Here, we report silver/polyaniline (Ag/PANI) nanocomposites obtained through a two-phase water/toluene interfacial reaction. As prepared silver nanoparticles in toluene with oleylamine as a reducing and stabilizing agent, were used as nucleation centers for the polymerization of aniline. Once the polymerization occurs at the interface of the organic (containing the aniline and the silver nanoparticles) and aqueous (containing the oxidizing ammonium persulfate agent) phase, the polymer grows around the silver nanoparticles and forming the nanocomposite structure. The formation of Ag/PANI nanocomposite was characterized by UV–Vis and FTIR spectroscopy, and transmission electron microscopy. In contrast to pure PANI, the absorption spectrum of Ag/PANI nanocomposite showed additional strong band assigned to surface plasmon resonance absorption of the electrons in the conducting silver bands