Nickel Catalysts on Porous Ceramic Supports for the Reaction of Partial Oxidation of Propane to CO and H2

In this paper synthesis, textural and structural properties as well as selectivity of Ni based catalysts for partial oxidation of propane to CO and H2 are given. The influence of aluminosilicate and magnesia based porous ceramic supports on catalyst performance is emphasized. The influence of concentration of impregnation solution, number of successive impregnations and nature of modifier was investigated. The catalytic test was performed in order to define the catalyst with the highest selectivity toward CO and H2 while the presence of side-products like CO2, CH4, and coke as well as unreacted C3H8 are reduced to minimum. All synthesized catalysts samples were dominantly macroporous. The selectivity of catalysts increased with presence of modifiers in the following order: CaO < MgO < Al2O3. The selectivity of studied catalysts is governed mainly by two structural parameters: nickel loading and nickel crystallite size. The comparison of the best performing aluminosilicate and magnesia supported catalysts with Al as modifier revealed that the latter express somewhat lower selectivity particularly toward CO

The influence of conditions of forming composite coating polymer-magnetic powder on physico-mechanical properties of telecommunication optical fibers

Fеrоmаgnеtskа kоmpоzitnа prеvlаkа nа оptičkоm vlаknu оmоgućаvа idеntifikаciјu i dеtеkciјu tеlеkоmunikаciоnih оptičkih vlаkаnа/kаblоvа nаkоn njihоvоg pоlаgаnjа, primеnоm stаndаrdnih mаgnеtskih mеtоdа. U оvоm rаdu su dоbiјаnа оptičkа vlаknа sа kоmpоzitnоm fеrоmаgnеtskоm prеvlаkоm. Dеfinisаn је i оptimizоvаn prоcеsа njihоvоg dоbiјаnjа i vršеnа njеgоvа numеričkа simulаciја. Kоmpоzitnа prеvlаkа fоrmirаnа је prеvlаčеnjеm оptičkih vlаkаnа dispеrziјоm prаhоvа Bа-fеritа i SmCo5 u rаstvоru ЕVA u tоluеnu. Rаvnоmеrnоst dеblјinе kоmpоzitnе prеvlаkе ispitivаnа је kоrišćеnjеm mikrоskоpа sа оdbiјеnоm svеtlоšću. Аnаlizа mikrоskоpskih slikа bilа је оmоgućеnа kоrišćеnjеm sistеmа: mikrоskоp- digitаlnа kаmеrа- pеrsоnаlni rаčunаr sа оdgоvаrајućim prоgrаmоm zа kvаntifikаciјu vizuеlnih infоrmаciја. Rеzultаti dоbiјеni аnаlizоm slikе оbrаđеni su mаtеmаtičkо-stаtističkоm mеtоdоm. Ispitаn је uticај brzinе prеvlаčеnjа, kоncеntrаciје pоlimеrа i mаgnеtnоg prаhа u dispеrziјi nа rаvnоmеrnоst dеblјinе kоmpоzitnе prеvlаkе pоlimеr mаgnеtni prаh. Kао kritеriјum zа dеfinisаnjе unifоrmnе dеblјinе kоmpоzitnе prеvlаkе usvојеnа је nајmаnjа vrеdnоst stаndаrdnе dеviјаciје nајvеrоvаtniје vrеdnоsti prеčnikа оptičkоg vlаknа sа kоmpоzitnоm prеvlаkоm. Nа оsnоvu еkspеrimеntаlnih rеzultаtа, utvrđеnо је dа sе uticај svih istrаživаnih prоcеsnih pаrаmеtаrа nа rаvnоmеrnоst prеvlаkе, mоžе svеsti nа uticај viskоznоsti dispеrziје kојоm sе vrši prеvlаčеnjе. Ustаnоvlјеnа је оptimаlnа vrеdnоst viskоznоsti dispеrziје оd 1,20-1,24 Pas, zа ispitаni sistеm, kоја оmоgućаvа fоrmirаnjе kоmpоzitnе prеvlаkе nајrаvnоmеrniје dеblјinе. Pоtvrđеnо је dа svе prоcеsnе pаrаmеtrе: kоncеntrаciјu pоlimеrа i mаgnеtnоg prаhа, brzinu i tеmpеrаturu prеvlаčеnjа trеbа usklаditi tаkо dа sе prеvlаčеnjе оdviја dispеrziјоm čiја је viskоznоst оptimаlnа. Nа оsnоvu еkspеrimеntаlnо utvrđеnih rеоlоških јеdnаčinа zа pоnаšаnjе dispеrznоg sistеmа (prаhоvi Bа-fеritа ili SmCo5 dispеrgоvаni u rаstvоru ЕVА u tоluеnu) i pоstојеćеg mаtеmаtičkоg mоdеlа zа prеvlаčеnjе оptičkih vlаkаnа pоlimеrnоm prеvlаkоm rаzviјеn је mаtеmаtički mоdеl fоrmirаnjа kоmpоzitnе prеvlаkе nа оptičkоm vlаknu kојi је оmоgućiо numеričku simulаciјu prоcеsа prеvlаčеnjа оptičkih vlаkаnа kоmpоzitnоm prеvlаkоm. Numеričkоm simulаciјоm оmоgućеnо је ispitivаnjе uticаја vеćеg brоја prоcеsnih pаrаmеtаrа i оnih kојi nisu bili еkspеrimеntаlnо ispitivаni. Utvrđеnо је dа dеblјinа prеvlаkе nајvišе zаvisi оd gеоmеtriјskih kаrаktеristikа sistеmа zа prеvlаčеnjе. Vаlidnоst mоdеlа pоtvrđеnа је dоbrim slаgаnjеm rеzultаtа numеričkе simulаciје sа еkspеrimеntаlnim. Dоbiјеnа оptičkа vlаkаnа sа kоmpоzitnоm prеvlаkоm zаdržаvајu trаnsmisiоnа i pоbоlјšаvајu mеhаničkа svојstvа. Pri dејstvu spоlјаšnjеg јеdnоsmеrnоg i nаizmеničnоg mаgnеtnоg pоlја nа оptičkо vlаknо sа fеrоmеgnеtskоm kоmpоzitnоm prеvlаkоm nе dоlаzi dо prоmеnе u snаzi prеnеsеnе svеtlоsti. Ispitаnа оptičkа vlаknа mоgućе је kоristiti kао tеlеkоmunikаciоnа оptičkа vlаknа kоја sе mоgu lоcirаti kоrišćеnjеm mаgnеtnih mеtоdа.The ferromagnetic composite coating on optical fiber enables identification and detection of telecommunication optical fibers/cables after they have been laid down, using standard magnetic methods. In this thesis the optical fibers with composite ferromagnetic coating were obtained. The process of their synthesis was defined and optimized and numerical simulation of this process was performed. The composite coating was formed by coating optical fibers with dispersion of Ba-ferrite and SmCo5 powders in EVA solution in toluene. The coating thickness uniformity was investigated using optical microscope with reflective light. The analysis of microscope images was performed using the system: microscope - digital camera- personal computer with appropriate software for quantification of visual information. These results were evaluated using mathematical-statistic methods. The influence of coating rate, concentration of polymer and magnetic powder in dispersion on polymer-magnetic powder composite coating thickness was investigated. As criteria for defining uniform thickness of composite coating the minimal value of standard deviation of mean value of diameter of optical fiber with composite coating was established. According to experimental results it was found out that the influence of all investigated process parameters on coating uniformity ends up as the influence of viscosity of coating dispersion. For investigated system, the optimal value of viscosity of dispersion that enables forming the composite coating of the most uniform thickness was established as 1.20-1.24 Pa s. It was confirmed that all process parameters: concentration of polymer and magnetic powder and coating rate and temperature should be established in that manner that coating is performed with the evaluated optimal viscosity of dispersion. According to the experimentally estimated rheological equation for behavior of dispersed system (powders of Ba-ferrite and SmCo5 dispersed in EVA solution in toluene) and existing mathematical model for coating optical fibers with polymer coating the mathematical model of forming composite coating on optical fiber was established and enabled the numerical simulation of process of coating optical fibers with composite coating. By using numerical simulation it was possible to investigate higher number of process parameters and those that were not experimentally investigated. It was established that the coating thickness mostly depends on geometrical properties of the coating system. Validity of model was confirmed by good agreement of results obtained with numerical simulation with experimental. The obtained optical fibers with composite coating keep their transmission properties and improve mechanical. No change in the power of the propagated laser beam through the fiber optic with composite ferromagnetic coating was observed when external DC and AC magnetic fields were applied. It is possible to use the developed optical fibers as telecommunication optical fibers detectable by magnetic methods

The influence of conditions of forming composite coating polymer-magnetic powder on physico-mechanical properties of telecommunication optical fibers

Fеrоmаgnеtskа kоmpоzitnа prеvlаkа nа оptičkоm vlаknu оmоgućаvа idеntifikаciјu i dеtеkciјu tеlеkоmunikаciоnih оptičkih vlаkаnа/kаblоvа nаkоn njihоvоg pоlаgаnjа, primеnоm stаndаrdnih mаgnеtskih mеtоdа. U оvоm rаdu su dоbiјаnа оptičkа vlаknа sа kоmpоzitnоm fеrоmаgnеtskоm prеvlаkоm. Dеfinisаn је i оptimizоvаn prоcеsа njihоvоg dоbiјаnjа i vršеnа njеgоvа numеričkа simulаciја. Kоmpоzitnа prеvlаkа fоrmirаnа је prеvlаčеnjеm оptičkih vlаkаnа dispеrziјоm prаhоvа Bа-fеritа i SmCo5 u rаstvоru ЕVA u tоluеnu. Rаvnоmеrnоst dеblјinе kоmpоzitnе prеvlаkе ispitivаnа је kоrišćеnjеm mikrоskоpа sа оdbiјеnоm svеtlоšću. Аnаlizа mikrоskоpskih slikа bilа је оmоgućеnа kоrišćеnjеm sistеmа: mikrоskоp- digitаlnа kаmеrа- pеrsоnаlni rаčunаr sа оdgоvаrајućim prоgrаmоm zа kvаntifikаciјu vizuеlnih infоrmаciја. Rеzultаti dоbiјеni аnаlizоm slikе оbrаđеni su mаtеmаtičkо-stаtističkоm mеtоdоm. Ispitаn је uticај brzinе prеvlаčеnjа, kоncеntrаciје pоlimеrа i mаgnеtnоg prаhа u dispеrziјi nа rаvnоmеrnоst dеblјinе kоmpоzitnе prеvlаkе pоlimеr mаgnеtni prаh. Kао kritеriјum zа dеfinisаnjе unifоrmnе dеblјinе kоmpоzitnе prеvlаkе usvојеnа је nајmаnjа vrеdnоst stаndаrdnе dеviјаciје nајvеrоvаtniје vrеdnоsti prеčnikа оptičkоg vlаknа sа kоmpоzitnоm prеvlаkоm. Nа оsnоvu еkspеrimеntаlnih rеzultаtа, utvrđеnо је dа sе uticај svih istrаživаnih prоcеsnih pаrаmеtаrа nа rаvnоmеrnоst prеvlаkе, mоžе svеsti nа uticај viskоznоsti dispеrziје kојоm sе vrši prеvlаčеnjе. Ustаnоvlјеnа је оptimаlnа vrеdnоst viskоznоsti dispеrziје оd 1,20-1,24 Pas, zа ispitаni sistеm, kоја оmоgućаvа fоrmirаnjе kоmpоzitnе prеvlаkе nајrаvnоmеrniје dеblјinе. Pоtvrđеnо је dа svе prоcеsnе pаrаmеtrе: kоncеntrаciјu pоlimеrа i mаgnеtnоg prаhа, brzinu i tеmpеrаturu prеvlаčеnjа trеbа usklаditi tаkо dа sе prеvlаčеnjе оdviја dispеrziјоm čiја је viskоznоst оptimаlnа. Nа оsnоvu еkspеrimеntаlnо utvrđеnih rеоlоških јеdnаčinа zа pоnаšаnjе dispеrznоg sistеmа (prаhоvi Bа-fеritа ili SmCo5 dispеrgоvаni u rаstvоru ЕVА u tоluеnu) i pоstојеćеg mаtеmаtičkоg mоdеlа zа prеvlаčеnjе оptičkih vlаkаnа pоlimеrnоm prеvlаkоm rаzviјеn је mаtеmаtički mоdеl fоrmirаnjа kоmpоzitnе prеvlаkе nа оptičkоm vlаknu kојi је оmоgućiо numеričku simulаciјu prоcеsа prеvlаčеnjа оptičkih vlаkаnа kоmpоzitnоm prеvlаkоm. Numеričkоm simulаciјоm оmоgućеnо је ispitivаnjе uticаја vеćеg brоја prоcеsnih pаrаmеtаrа i оnih kојi nisu bili еkspеrimеntаlnо ispitivаni. Utvrđеnо је dа dеblјinа prеvlаkе nајvišе zаvisi оd gеоmеtriјskih kаrаktеristikа sistеmа zа prеvlаčеnjе. Vаlidnоst mоdеlа pоtvrđеnа је dоbrim slаgаnjеm rеzultаtа numеričkе simulаciје sа еkspеrimеntаlnim. Dоbiјеnа оptičkа vlаkаnа sа kоmpоzitnоm prеvlаkоm zаdržаvајu trаnsmisiоnа i pоbоlјšаvајu mеhаničkа svојstvа. Pri dејstvu spоlјаšnjеg јеdnоsmеrnоg i nаizmеničnоg mаgnеtnоg pоlја nа оptičkо vlаknо sа fеrоmеgnеtskоm kоmpоzitnоm prеvlаkоm nе dоlаzi dо prоmеnе u snаzi prеnеsеnе svеtlоsti. Ispitаnа оptičkа vlаknа mоgućе је kоristiti kао tеlеkоmunikаciоnа оptičkа vlаknа kоја sе mоgu lоcirаti kоrišćеnjеm mаgnеtnih mеtоdа.The ferromagnetic composite coating on optical fiber enables identification and detection of telecommunication optical fibers/cables after they have been laid down, using standard magnetic methods. In this thesis the optical fibers with composite ferromagnetic coating were obtained. The process of their synthesis was defined and optimized and numerical simulation of this process was performed. The composite coating was formed by coating optical fibers with dispersion of Ba-ferrite and SmCo5 powders in EVA solution in toluene. The coating thickness uniformity was investigated using optical microscope with reflective light. The analysis of microscope images was performed using the system: microscope - digital camera- personal computer with appropriate software for quantification of visual information. These results were evaluated using mathematical-statistic methods. The influence of coating rate, concentration of polymer and magnetic powder in dispersion on polymer-magnetic powder composite coating thickness was investigated. As criteria for defining uniform thickness of composite coating the minimal value of standard deviation of mean value of diameter of optical fiber with composite coating was established. According to experimental results it was found out that the influence of all investigated process parameters on coating uniformity ends up as the influence of viscosity of coating dispersion. For investigated system, the optimal value of viscosity of dispersion that enables forming the composite coating of the most uniform thickness was established as 1.20-1.24 Pa s. It was confirmed that all process parameters: concentration of polymer and magnetic powder and coating rate and temperature should be established in that manner that coating is performed with the evaluated optimal viscosity of dispersion. According to the experimentally estimated rheological equation for behavior of dispersed system (powders of Ba-ferrite and SmCo5 dispersed in EVA solution in toluene) and existing mathematical model for coating optical fibers with polymer coating the mathematical model of forming composite coating on optical fiber was established and enabled the numerical simulation of process of coating optical fibers with composite coating. By using numerical simulation it was possible to investigate higher number of process parameters and those that were not experimentally investigated. It was established that the coating thickness mostly depends on geometrical properties of the coating system. Validity of model was confirmed by good agreement of results obtained with numerical simulation with experimental. The obtained optical fibers with composite coating keep their transmission properties and improve mechanical. No change in the power of the propagated laser beam through the fiber optic with composite ferromagnetic coating was observed when external DC and AC magnetic fields were applied. It is possible to use the developed optical fibers as telecommunication optical fibers detectable by magnetic methods

Influence of bentonite filler on the thermal stability of glycidyl methacrylate based composite

Macroporous crosslinked copolymer of glycidyl methacrylate, GMA, and ethylene glycol dimethacrylate, EGDMA, poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) and its composites were synthesized by suspension copolymerization. Composites were obtained by introducing 10 mass % of either raw bentonite (S0) or acid modified bentonite (SA) into reaction system. The composite synthesized with SA as filer showed superior thermal stability comparing to starting copolymer and composite with S0 embedded in copolymer matrix

Deletion/Deletion Genotype of Angiotensin-I Converting Enzyme Gene is not Associated with Coronary Artery Disease in Caucasians with Type 2 Diabetes

In this study we analyzed the contribution of genetic variability of the insertion/deletion (I/D) polymorphism of the angiotensin-I converting enzyme (ACE) gene to the predisposition for coronary artery disease (CAD) in a group of patients with type 2 diabetes. The I/D ACE gene polymorphism was tested in 366 Caucasians with type 2 diabetes: 148 cases with CAD and 218 subjects with no history of CAD. We failed to demonstrate that the ACE DD genotype was a risk factor for CAD in Caucasians with type 2 diabetes (OR 2.0, 95 % CI 0.9–4.7; p=0.1). In conclusion, we provide evidence that the ACE deletion/deletion genotype is not a risk factor for CAD in Caucasians with type 2 diabetes

Expression of CD31, CD34, and smooth muscle actin (SMA) in endothelial cells of dental pulp vessels

The dental pulp is a highly vascularized and innervated loose connective tissue surrounded by hard dental tissues – enamel and dentine. With the primary dentin formation and the closure of the root apex, the conditions in the dental pulp change and pulp tissue compliance are reduced. Endothelial cells of pulpal blood vessels are highly differentiated and are capable of adaptation to changes in the environment. We aimed to evaluate the phenotypic plasticity of endothelial cells of pulpal blood vessels in permanent premolars with open (N = 6) or closed root apex (N = 30). The pulp tissue was stained with hematoxylin-eosin (HE) for the histological analysis, and immunohistochemically for a cluster of differentiation 31 (CD31), a cluster of differentiation 34 (CD34), and for smooth muscle actin (SMA) to detect vessels with CD31, CD34, and SMA positive endothelial cells. We used the student’s t-test and Pearson correlation test for the statistical analysis. We found a significantly higher percentage of the vessels with CD31 (P = 0.005) and CD34 (P = 0.000) positive endothelial cells in the group of teeth with closed root apex compared to the group with open apex. A significant positive correlation between SMA positive and CD31 positive vessels (P = 0.003) and between CD31 positive and CD34 positive vessels (P = 0.031) was also found. We conclude that the endothelial cells of dental pulp vessels express a small amount of CD31, but have a pronounced expression of SMA and CD34, which indicates their progenitor potential and contractile ability

Influence of air pollution on hospital admissions for cardiovascular and respiratory diseases in Niš, Serbia

Background/Aim. In studies that investigate the health effects of short-term air pollution exposure, population-wide changes in acute outcomes such as mortality, hospital admissions and healthcare visits are linked to short-term variations in ambient pollutant concentrations. The aim of this study was to estimate the association between daily outdoor black smoke and sulphur dioxide levels and hospital admissions for cardiovascular and respiratory diseases in Niš, within a period 2001-2005. Methods. A time series analysis was performed using separated regression models for each pollutant and disease group, by age groups and population as a whole. The effects of copollutant, meteorological factors and cyclic oscillations in hospitalization numbers were controlled. Results. A significant increase in hospital admissions was associated with a 10 μg/m3 increase in the concentration of black smoke, for cardiovascular diseases: 3.14% (&lt; 0.01) in children and youth under 19 years of age, 1.85% (&lt; 0.001) in 19-64 age group, and 0.84% (&lt; 0.05) in all ages, and for respiratory diseases: 1.77% (&lt; 0.05) in 19-64 age group, and 0.91% (&lt; 0.05) in all ages. The effects on hospitalizations for respiratory diseases in children and youth under 19 years of age, and for cardiovascular and respiratory diseases in the elderly were not statistically significant. The increase of sulphur dioxide level was associated with the increased number of hospitalizations, for both cardiovascular and respiratory diseases in all age groups, but the influence was not statistically significant. Conclusion. Outdoor pollutants concentrations in urban area of Niš were below regulated limit values during most of the investigated period days but it is shown that even such a level of pollution has a significant effect on hospital admissions for cardiovascular and respiratory diseases

Textile dye sorption by porous aminofunctionalized copolymer

Macroporous hydrophilic copolymers based on glycidyl methacrylate, GMA, proved very useful as sorbents and column packing in different types of chromatography, as enzyme supports, in biotechnological and biomedical applications, for heavy and precious metal sorption, the sorption of organic compounds, etc. In this paper, macroporous copolymer of GMA and ethylene glycol dimethacrylate, EGDMA, poly(GMA-co-EGDMA) [abbreviated PGME] was synthesized by suspension copolymerization. Copolymer was additionally functionalized via ring-opening reaction of the pendant epoxy groups with diethylene triamine [PGME-deta] and tested as acid textile dye sorbent

Model izvlačenja tankih staklenih traka iz predoblika

A one-dimensional model of thin glass sheet drawing has been developed. This model includes momentum, heat and mass balance equations. The density, viscosity and specific heat of the glass were calculated as functions of temperature, and the glass emissivity was defined and calculated as a function of both temperature and glass thickness. After allowed simplifications, two ordinary differential equations were obtained and solved using the Runge Kutte method. The model was used to investigate the influence of different process parameters (the velocity of lowering the preform into the furnace, the axial temperature profile of the furnace, the drawing force and its direction, etc.) on the change in the shape of the drawn glass sheet for different glass compositions and various geometrical characteristics of the preform. A laboratory device for drawing glass sheets from rectangular preforms enabled full control of the process parameters, their measurement, as well as data acquisition. The results of the numerical simulation were compared with the experimental data and good agreement between them was found

Influence of the phase composition of refractory materials on creep

In this paper, the relationship between the creeping effect and mineralogical characteristics of the applied binding phase for various refractory materials (high-alumina materials, with high or low impurity content, tar bonded either magnesite or dolomite materials and silicate bonded chrom-magnesite materials) is presented. The mechanism of creeping is analyzed and the activation energy for creep for each investigated material is obtained and discussed. All investigated materials are creep sensitive under investigated conditions and have similar activation energies for creep except high-alumina refractories with a low impurity content.U radu je data veza puzanja vatrostalnih materijala i mineraloških karakteristika vezivnih faza za različite vatrostalne materijale (visokoaluminatne, katranom vezane magnezitne, katranom vezane dolomitne materijale i silikatno vezane hrommagnezitne materijale). Pored toga analiziran je mehanizam puzanja i proračunata je energija aktivacije procesa puzanja za svaki od ispitivanih materijala