Two step sintering of the ZnTiO3 nanopowder

Metastabile nanopowder ZnTiO3 pressed into cylindrical compacts at 200 MPa was submitted to conventional heating with isothermal holding at 931oC for 10 minutes, 25 minutes and 40 minutes. Same compacts were heated with two-step sintering schedule with maximal 912oC and isothermal holding at 896oC, for approximately the same holding times as with isothermal. Shrinkage during heating was monitored with dilatometric device, while microstructure was determined with atomic force microscopy. XRD patterns were collected for the most prominent samples. Sintered specimens microstructure showed differences introduced during last sintering stage by two heating schedules

Nano Design of Biphasic ciumphosphate/Poly-Dl-Lactide- Co-Glycolide, as Composite Biomaterials for Hard Tissue Reconstruction

Poster presented at the The Seventh Yugoslav Materials Research Society Conference - YUCOMAT 2005, Herceg Novi, Montenegro, September 12-16, 2005

Obtaining nano calcium phosphate/poly(dl-lactide-coglycolide) composite biomaterial by sonochemical deagglomeration

Nanoparticles have several advantages over the microparticles in interactions of thebiomaterial with the organism. The response of the organism depends on the interaction of thebiomaterial with the surrounding tissue and its adhesion to cells. Besides composition andmorphology, the size and size distribution of the composite particles plays a key role in thesephenomena.This paper shows possibilities of synthesizing composite biomaterials calciumphosphate/poly-(dl-lactide-co-glycolide) (CP/DLPLG) formed as nanoparticles (NPs) powders.Each CP nanoparticle was coated with amorphous DLPLG polymer. In dispersion, particles canbe deagglomerated by ultrasound treatment.The size distribution of calcium phosphate coated with poly-(dl-lactide-co-glycolide)(CP/DLPLG) was obtained by dynamic light scattering (DLS). Agglomerate of CP/DLPLG wasinvestigated by atomic force microscopy (AFM) before and after ultrasound treatment.Results obtained at different time of ultrasound treatment showed a significantinfluence of ultrasound treatment on deagglomeration of powder CP/DLPLG. Fine particlefractions were found to increase time of ultrasound treatment from 30 to 120 minutes

Two step sintering of the ZnTiO3 nanopowder

Metastabile nanopowder ZnTiO3 pressed into cylindrical compacts at 200 MPa was submitted to conventional heating with isothermal holding at 931oC for 10 minutes, 25 minutes and 40 minutes. Same compacts were heated with two-step sintering schedule with maximal 912oC and isothermal holding at 896oC, for approximately the same holding times as with isothermal. Shrinkage during heating was monitored with dilatometric device, while microstructure was determined with atomic force microscopy. XRD patterns were collected for the most prominent samples. Sintered specimens microstructure showed differences introduced during last sintering stage by two heating schedules

Two step sintering of the ZnTiO3 nanopowder

Metastabile nanopowder ZnTiO3 pressed into cylindrical compacts at 200 MPa was submitted to conventional heating with isothermal holding at 931oC for 10 minutes, 25 minutes and 40 minutes. Same compacts were heated with two-step sintering schedule with maximal 912oC and isothermal holding at 896oC, for approximately the same holding times as with isothermal. Shrinkage during heating was monitored with dilatometric device, while microstructure was determined with atomic force microscopy. XRD patterns were collected for the most prominent samples. Sintered specimens microstructure showed differences introduced during last sintering stage by two heating schedules

Detection of target substances using affinitz based MEMS/NEMS sensors: a problem of selectivity

Affinity-based micro/nanosensors intended for detection of various chemical or biological agents in a liquid or gaseous environment have a great potential for both civilian and military applications. Selective detection of a target substance is based on highly specific binding of its particles to the functionalized surface of the sensing element. However, samples taken from the environment often contain substances other than the target, which can also bind with a certain affinity to the same functionalizing layer or binding sites, thus affecting the sensor's response. In this paper we analyze the influence of limited selectivity of a sensor on its time response. The results show that binding of a non-target substance can cause a significant change in both the equilibrium value and the rate of the sensor's response. The presented analysis enables improvement of accuracy of determination of the target substance concentration in detection methods based on time domain measurements of the sensor's output signal. It is also useful for development of methods for simultaneous detection of multiple substances

Monolayer Gas Adsorption on Graphene-Based Materials: Surface Density of Adsorption Sites and Adsorption Capacity

Surface density of adsorption sites on an adsorbent (including affinity-based sensors) is one of the basic input parameters in modeling of process kinetics in adsorption based devices. Yet, there is no simple expression suitable for fast calculations in current multiscale models. The published experimental data are often application-specific and related to the equilibrium surface density of adsorbate molecules. Based on the known density of adsorbed gas molecules and the surface coverage, both of these in equilibrium, we obtained an equation for the surface density of adsorption sites. We applied our analysis to the case of pristine graphene and thus estimated molecular dynamics of adsorption on it. The monolayer coverage was determined for various pressures and temperatures. The results are verified by comparison with literature data. The results may be applicable to modeling of the surface density of adsorption sites for gas adsorption on other homogeneous crystallographic surfaces. In addition to it, the obtained analytical expressions are suitable for training artificial neural networks determining the surface density of adsorption sites on a graphene surface based on the known binding energy, temperature, mass of adsorbate molecules and their affinity towards graphene. The latter is of interest for multiscale modelling

ZnTiO3 Ceramic Nanopowder Microstructure Changes During Compaction

ZnTiO3 nanopowder as a constitutive component in compact production was primarily characterised. Scanning electron micrographs of as received powder were recorded. Mercury porosimetry and nitrogen adsorption were also performed on loose powder. Particle size distribution in a water powder suspension was determined with a laser particle size analyser. Compaction was performed on different pressures in a range from 100 to 400 MPa using the uniaxial double sided compaction technique without binder and lubricant. Micrographs of compacted specimens were obtained using scanning electron microscopy and atomic force microscopy. Pore size distribution was also determined by mercury porosimetry and nitrogen adsorption. Results revealed that with increasing pressure during compaction interagglomerate pores diminish in size until they reach some critical diameter related to the intra-agglomerate pore size

Supplementary material for: "Visible light promoted photoredox C(sp3)-H bond functionalization of tetrahydroisoquinolines in flow"

Full characterization data for all compounds.The supplementary material for: Filipović, A., Džambaski, Z., Vasiljević-Radović, D. G.,& Bondžić, B. P. (2021). Visible light promoted photoredox C(sp3)-H bond functionalization of tetrahydroisoquinolines in flow. Organic and Biomolecular Chemistry, Royal Society of Chemistry., 19(12), 2668-2675. [https://doi.org/10.1039/d0ob02582h]The published version of the article: [https://cer.ihtm.bg.ac.rs/handle/123456789/4494

Improved Oxygen Reduction on GC-Supported Large-Sized Pt Nanoparticles by the Addition of Pd

PdPt bimetallic nanoparticles on carbon-based supports functioning as advanced electrode materials have attracted attention due to their low content of noble metals and high catalytic activity for fuel cell reactions. Glassy carbon (GC)-supported Pt and PdPt nanoparticles, as promising catalysts for the oxygen reduction reaction (ORR), were prepared by the electrochemical deposition of Pt and the subsequent spontaneous deposition of Pd. The obtained electrodes were examined using X-ray Photoelectron Spectroscopy (XPS), Atomic Force Microscopy (AFM), and electroanalytical techniques. An XPS analysis of the PdPt/GC with the highest ORR performance revealed that the stoichiometric ratio of Pd: Pt was 1:2, and that both Pt and Pd were partially oxidized. AFM images of PdPt2/GC showed the full coverage of GC with PdPt nanoparticles with sizes from 100–300 nm. The ORR activity of PdPt2/GC in an acid solution approached that of polycrystalline Pt (E1/2 = 0.825 V vs. RHE), while exceeding it in an alkaline solution (E1/2 = 0.841 V vs. RHE). The origin of the improved ORR on PdPt2/GC in an alkaline solution is ascribed to the presence of a higher amount of adsorbed OH species originating from both PtOH and PdOH that facilitated the 4e-reaction pathway