•HRTEM images revealed that the size of the nanoparticles are 100 nm and smaller.•Nanocrystalline Al2SiO5 particles can be partially amorphized under temperature.•The “triple point” in the DTA ...spectra is observed at 850 K.•At the cooling process the evaluated And – Sil transition stopped in small quantities.
DTA, TGA, and DTG methods were applied at different heating rates to comparative study of thermal parameters of nanocrystalline Al2SiO5particles. Hydroxyl groups on the surface of the nanoparticles and the process of their release under the influence of temperature were explained by the corresponding DSC spectra. Simultaneously, the size and composition of the nanoparticles were measured by HRTEM imaging and EDX analysis. Possible andalusite − sillimanitetransitionofAl2SiO5modifications, andamorphization processes under the influence of temperaturewere investigated by the DTA approach. Around 850 K “triple point” of Al2SiO5modifications was analyzed by the DSC spectroscopy.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
Thermal properties of nanocrystalline silicon carbide (3C-SiC) particles were performed depending on the thermal processing rate. The kinetical parameters (heat flux, oxidation reaction rate and ...activation energy) of thermal effects occurring in the silicon carbide nanoparticles with 99.5 +% purity have been determined by 5, 10, 15 and 20 K/min heating rate in the temperature range of 300–1270 K. Activation energies of nanocrystalline 3C-SiC particles were calculated by Arrhenius approximation at different thermal processing rates.
Full text
Available for:
DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Several thermal parameters were analyzed for nanocrystalline silicon carbide (3C-SiC) particles at the performed depending on the thermal processing rate. The hydroxyl groups on the surface of ...nanocrystalline 3C-SiC particles have been investigated as a function of temperature and heating rate. Specific heat capacity and Gibbs energy of silicon carbide nanoparticles have been determined in the temperature range of 300–1270 K at various heating rates. The enthalpy and the entropy were calculated at different thermal processing rates (theoretical calculations are confirmed based on experimental results). Experimental results obtained for all thermophysical parameters were comparatively studied at different thermal processing rates.
Full text
Available for:
DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Nanocrystalline silicon carbide (3C–SiC) particles were irradiated by neutron flux up to 5 h at the TRIGA Mark II type research reactor. DSC (Differential Scanning Calorimetry), DTA (Differential ...Thermic Analysis), TGA (Thermogravimetric Analysis) and DTG (Differential Thermogravimetric Analysis) analyzes (in cooling and heating processes) of nanocrystalline silicon carbide (3C–SiC) particles were carried out before and after neutron irradiation. It was revealed that the neutron irradiation causes a change in the numerical value of heat flux. Moreover, it has been shown that the oxidation process is relatively slow due to the influence of the neutrons. It was determine that the numerical value of specific heat capacity is characteristic (500 ÷ 750 J kg−1K−1) for 3C–SiC nanocrystals.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
Heat flux and mass change of AlN nanoparticles at the different heating rates were considered as a function of temperature. The Gibbs energy of the AlN nanoparticles system was determined in the ...temperature range of 300 ÷ 1400K, at the heating rates as 5, 10, 15 and 20 K/min. Experiments in heating and cooling processes were carried out separately and the results were analyzed. The surface oxidation process under the influence of temperature is formed AlxNyOz compound, which is explained by phonon oscillations on the Raman spectrum. The hydroxide effect on crystallization and properties of the material is clear on the Raman spectrum. Simultaneously, on the surface of nanoparticles Al(OH)3 or AlOOH are formed as a result of the hydration, and phonon oscillations are observed. Moreover, as a result of the temperature effect, VN and VAl3−−3×ON+ defect complexes can be formed in the sample. Space symmetry of AlN nanoparticles and preserving the crystalline structure at the nanoscale were investigated by the XRD method. The size and surface imaging of nanoparticles were studied using HRTEM analyses.
•It was found that the oxidation process starts in AlN nanoparticles at temperatures above 600K.•Impurities start to escape from the surface of nanoparticles in parallel, which causes a decrease in mass up to the temperature of 1200K.•The equilibrium state at 1200K was determined using Gibbs energy, entropy, and enthalpy curves.•VN and VAl3−−3×ON+ defect complexes formed in the sample with energy depths of Ec-0.8 eV and Ev+2.53 eV, respectively.•AlN nanoparticles have a hexagonal space symmetry and preserve the crystalline structure at nanoscale.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
Paramagnetic centers and their character in the nanocrystalline h-BN particles were investigated before and after neutron irradiation. Color changing in a neutron irradiated h-BN nanoparticles was ...analyzed by new formed EPR signal. Electron Paramagnetic Resonance (EPR) analysis was performed at room temperature in the range of 500÷5500 G with 3300 G central line. The 0.3270–0.3370 T region, where more paramagnetic centers are observed, was additionally considered. New paramagnetic centers formed by the neutron flux in h-BN nanoparticles have been explained by EPR spectra.
•After neutron irradiation light-pink color-changing of BN nanoparticles is symmetrically observed EPR signal.•Stable signals were detected in accordance with the parameters gX = 2.003252, ΔBX ∼22G and gY = 2.003252, ΔBY ∼110G.•The transition from B2N4 to B3N3 structure is pssible with thermal processing.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
Paramagnetic centers in the nanocrystalline boron nitride (h-BN) particles were comparatively studied before and after neutron irradiation. Electron Paramagnetic Resonance (EPR) spectroscopic ...analyzes were performed in the broad range of magnetic field from 0.05 to 0.55 T (500–5500 Gauss). The range of 0.3270–0.3370 T was additionally sweeped, where more paramagnetic centers were observed. The nature of the new paramagnetic centers formed as a result of neutron transmutation in the BN nanoparticles were examined by EPR spectra. Formation mechanism of VB and VN vacancies has been studied in detail by neutron transmutations.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
This retrospective study compares the perioperative outcomes of laparoscopic simple nephrectomy (LSN) in patients with urinary stone disease (USD) in comparison with LSNs performed for other ...etiological factors.
115 LSNs were identified from the two teaching hospitals' database. Depending on the etiological factors, patients were stratified in 2 groups. Group 1 consisted of 63 (mean age 44.8±1.7 21-71 years) patients; where the cause of non-functioning kidney was USD. Meanwhile, Group 2 included 52 (mean age was 43.6±2.0 19-78 years) patients; who underwent LSN because of other benign diseases. In both groups, a standardized transabdominal or retroperitoneal approach was used according to the discretion of the attending surgeon. Two groups were compared statistically in terms of perioperative parameters and standardized surgical complications.
The use of transperitoneal approach was higher in Group 1 (69.8% vs. 30.2%) compared to Group 2 (51.9% vs. 48.1%). Elective open conversion was needed in 3 and 2 patients in Groups 1 and 2, respectively. The results for mean operative time (108.9±4.0 min vs. 106.7±5.0), estimated blood loss (92.5±8.2 vs. 86.8±10.1 mL) and length of hospital stay (4.1±0.33 vs. 3.85±0.42 days) were similar between the groups. Despite intraoperative complications were similar between the groups, overall post-operative complications were significantly higher (17.5% vs. 3.8%) in Group 1. However, the rate of significant complications (Clavien 3-5) was similar between the groups.
The present study revealed that perioperative outcomes of patients undergoing LSN for USD are similar to those seen in patients undergoing LSN for other etiological factors.
PDF