Mechanically activated ceria

The reduction of comercial and mechanically activatedCeO2 powder at 1200 °C in an argon atmosphere was examined by XRD. Mechanical activation of oxide powder was performed by milling in a vibratory mill for different lengths of time. During 30 min of milling it came to the greatest change in crystallite size, as well as of lattice distortion of CeO2 while after 60 min of activation effect of milling on the CeO2 properties was negligible. Fired CeO2 was partly reduced but firing of 60 min milled CeO2 produced only CeO2-x with lattice parameter a = 0,550 nm.Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

Synthesis of apatite-type Ce4.67(SiO4)3O via glycinenitrate combustion

The pure Ce4.67(SiO4)3O with the apatite-type of structure was obtained for the first time from cerium nitrate, glycine and tetraethyl orthosilicate (TEOS) through the self-combustion of the gel. The solution of the reactants with the molar ratio of TEOS to water 1: 42 and glycine to NO3 ¯ 1: 3 was transformed into gel. During combustion of the gel the ash containing nanostructured CeO2 and noncrystalline SiO2 was formed. The phase identification and the measurement of the crystallite size was done by XRD diffraction. Ce4.67(SiO4)3O was synthesized from the ash subsequently fired in argon at 1200 °C.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Reactions responsible for mass loss during pressure less sintering of Si3N4 ceramics with LiYO2 additive

The reactions were investigated with emphasis on the mass loss during pressureless sintering of Si3N4 ceramics without powder bad. A Si3N4 powder compacts with LiYO2 additive were heat-treated at different temperatures under the pressure of N2 of 0.1 MPa.. The mass loss increased with increasing temperature as well as with increasing additive content. It is expected that the major mass loss should be caused by volatilisation of lithia due to its high vapour pressure. However, the results of the chemical analysis of the samples are in contradiction with this assumption.Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

Focal laryngeal dystonia: diagnostics, therapeutics and novelties in neurophysiologic research

Aim of study: To present and discuss diagnostic procedures, therapeutic options and novelties in neurophysiological research of laryngeal dystonia (LD), a rare movement disorder with an unknown cause affecting the intrinsic muscles of the larynx. Material and methods: 1) Literature overview of the on the standard guidelines in the diagnostics and treatment of LD; 2) The use of transcranial magnetic stimulation (TMS) in the neurophysiologic research of LD by investigation of cortical silent period (cSP) reflecting the intracortical inhibitory process mediated by GABAA and GABAB receptors; 3) The use of navigated TMS in mapping the laryngeal motor cortex by investigating the duration of cortical silent period in two LD cases, abductor and adductor LD type. Results: The study presents standard diagnostic, treatment of LD disorder, and results of investigation by groups from School of Medicine, University of Minnesota, Minneapolis, MN, USA and School of Medicine, University of Split, Croatia on the duration of cSP in vocal and cricothyroid muscles in LD patients and healthy control subjects. The research groups presented norms for cSP duration in vocal and cricothyroid muscle in healthy subjects and pointed to the altered (shortened) duration of the cSP in LD patients (adductor type). Conclusion: The cSP measure might be useful neurophysiologic biomarker for understanding the LD disorder. In LD, the cortical activation during phonation may not be efficiently or effectively associated with inhibitory processes, leading to muscular dysfunction. Promising techniques such as TMS might bring new light to the diagnosis and treatment of LD disorder

Focal laryngeal dystonia: diagnostics, therapeutics and novelties in neurophysiologic research

Aim of study: To present and discuss diagnostic procedures, therapeutic options and novelties in neurophysiological research of laryngeal dystonia (LD), a rare movement disorder with an unknown cause affecting the intrinsic muscles of the larynx. Material and methods: 1) Literature overview of the on the standard guidelines in the diagnostics and treatment of LD; 2) The use of transcranial magnetic stimulation (TMS) in the neurophysiologic research of LD by investigation of cortical silent period (cSP) reflecting the intracortical inhibitory process mediated by GABAA and GABAB receptors; 3) The use of navigated TMS in mapping the laryngeal motor cortex by investigating the duration of cortical silent period in two LD cases, abductor and adductor LD type. Results: The study presents standard diagnostic, treatment of LD disorder, and results of investigation by groups from School of Medicine, University of Minnesota, Minneapolis, MN, USA and School of Medicine, University of Split, Croatia on the duration of cSP in vocal and cricothyroid muscles in LD patients and healthy control subjects. The research groups presented norms for cSP duration in vocal and cricothyroid muscle in healthy subjects and pointed to the altered (shortened) duration of the cSP in LD patients (adductor type). Conclusion: The cSP measure might be useful neurophysiologic biomarker for understanding the LD disorder. In LD, the cortical activation during phonation may not be efficiently or effectively associated with inhibitory processes, leading to muscular dysfunction. Promising techniques such as TMS might bring new light to the diagnosis and treatment of LD disorder

Phase evolution of Si3N4 with Mg-exchanged zeolite additive

This paper deals with the chemical reactions and phase evolution during pressureless sintering of Si3N4 with Mg-exchanged zeolite as sintering additive. The XRD data show that the first MgO-rich liquid forms at as low as 1250 °C, which as a consequence results in a significant reduction of sintering temperature. At 1300 °C the β−Si3N4 phase had disappeared indicating its dissolution into the liquid phase. At 1500 °C the secondary phase had been completely converted into a glassy phase, however, no phase transformation from α−Si3N4 to β−Si3N4 had taken place. Thus the composition of this material consists of α−Si3N4 embedded in magnesium silicon oxynitride glassy phase.Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200

Crystal structure analysis of Nd-doped ceria solid solutions

This paper deals with Nd-doped ceria solid solutions: Ce1-xNdxO2-d with "x" ranging from 0 to 0.25. Six different powders were synthesized by applying the method based on selfpropagating room temperature reaction (SPRT) between metallic nitrates and sodium hydroxide. The method is known to assure very precise stoichiometry of the final product in comparison with a tailored composition. Rietveld refinement was employed to get structural information on the synthesized powder. An increase of Nd ion concentration increases the unit cell parameters and average bond distances. We have shown that all obtained powders were solid solutions with a fluorite-type crystal structure and all powder particles were of nanometric size (about 3 nm)

Djelovanje mono-kvaternernih i bis-kvaternernih piridinijumskih oksima na akutnu toksičnost i antiholinesterazno djelovanje karbarila, dioksakarba i karbofurana

The acute toxicities of insecticidal carbamates (Dioxacarb, Carbaryl and Carbofuran) were determined in mice by s. c. or i. p. injection, both in the absence and in the presence of atropine and several pyridinium oximes. Atropine had a beneficial effect on the toxicity of all the three carbamates, while the oximes varied in their effects. In the case of Carbaryl all oximes used increased its toxicity, while in Dioxacarb and Carbofuran poisoning some of them were effective. It was found that the oximes do not influence the action of carbamates on the activity of serum cholinesterase in vitro, in a way which could explain their effect on the toxicity of these compounds. It is concluded, that the use of oximes is contraindicated in cases of intoxication with Carbaryl, Dioxacarb and Carbofuran.Ispitana je akutna toksičnost karbamatnih insekticida dioksarba, karbarila i karbofurana (LD-50) s. c. ili i. p., sa simultanom primjenom atropina ili bez nje i nekoliko piridinijumskih oksima. Atropin je pokazao povoljan efekat u trovanjima sa sva tri karbamata, dok je djelovanje oksima bilo različito. U trovanjima karbarilom i karbofuranom gotovo svi oksimi su potencirali njihovo toksično djelovanje, dok su u trovanju dioksakarbom neki bili djelotvorni. Oksimi ne utiču na inhibiciju holinesteraze in vitro ovim karbamatima na način kojim bi se moglo rastumačiti njihovo in vivo djelovanje. Na temelju eksperimenata je zaključena da je upotreba oksima u trovanju karbarilom, dioksakarbom i karbofuranom kontraindikovana

Protective effects of some cholinolytics in armine poisoning

Ispitan je zaštitni efekat 9 holinolitika i jednog inhibitora holinacetilaze na miševima trovanim arminom. Zaštitni efekat kod 1 LD50 armina dobiven je s hidroksizinom, disipalorn i ponalidom. Antrenil i atropin metilnitrat u kombinaciji sa piridin aldoksim methloridom (PAM-2 CI) spasili su 50% tretiranih životinja od 4 LD50 armina, aturban i PAM-2 CI od 8 LD50 otrova.Nine cholinolytics and one choline aoetylase inhiihitor (Morin) have been examined as potential protecting agents against armine poisoning. Only Hydroxyzine, Disipal and Ponalid were found to protect mice against one LD50 of armine. In combination with pyridine 2-aldoxime methchloride (PAM-2-Cl) the best effect was found with Aturban, which protected 50 per cent of mice against 4 mg/kg of armine (X LD50). The quaternary cholinolytics Antrenyl and atropine, combined with PAM-2-Cl, protected about 50 per cent of animals against 4 X LD50 of armine, similarly to a combination of central cholinolytics. Tropenzylium and Hydroxyzine. Other cholinolytics showed weaker protective properties