Photoluminescence and electrical properties in Pr-modified (Ba1-xCax)TiO3 multifunctional ceramics

Mechanoluminescence materials, characterized with non-thermal light emission in response to mechanical stimuli, can have many applications in direct conversion of mechanical energy into light energy. The aim of this study was to develop wet chemistry approaches for the synthesis of the finest ceramic powders of barium calcium titanate for the use in the production of a mechanoluminescent detector. Wet chemistry route allows the control of the particle size of ceramic materials up to several nanometers. For the first time luminescence was recorded in Ba0.9Ca0.1TiO3 ceramics despite reports that light emission in BCT is possibly only over 23% of calcium content. The resulting ceramics showed high relative density, reasonable ferro and dielectric properties, and red light emission can be observed with the naked eye

Translucent zirconia polycrystals prepared from nanometric powders

The aim of the present study was investigation of synthesis and sinterability of nanometric zirconia solid solution powders containing 8 mol% and 3 mol% of Y2O3. The powders were prepared by the hydrothermal treatment of the co-precipitated gels, which resulted in very fine powders with particle sizes <10 nm. The main problem in application of such fine powders is their tendency to form hard agglomerates. To overcome this obstacle, the aqueous suspensions of the powders were subjected to the freeze drying. It resulted in the powders composed of very weak agglomerates which were broken under pressure as low as ∼1 MPa. The powder compacts were sintered in oxygen atmosphere to the state of closed porosity and then HIP-ed at 1300 °C to fully dense ceramics. The spectrophotometric investigations in the wave length range of 190–1100 nm indicated higher translucency of the 8 mol% Y2O3-ZrO2 than the 3 mol% Y2O3-ZrO2 ceramics. Most probably it should be related to the birefringence phenomenon which occurs in the latter case due to the tetragonal symmetry of this material. In the polycrystal containing 8 mol% of Y2O3 this phenomenon does not occur due to its cubic symmetry. The other two factors which lead to the decreased optical transparency of the material containing 3 mol% Y2O3 are its smaller grain sizes and the presence of some amount of the monoclinic phase

Hydroxyapatite of natural origin - zirconia composites, preparation and reactions within the system

The effect of 5 and 10 vol.% addition of zirconia (3Y-TOSOH) to hydroxyapatite of natural origin was investigated. The hydroxyapatite (HAp) material was extracted from the bovine bones by treatment under hydrothermal conditions with distilled water. The pure HAp and HAp-ZrO2 composites were manufactured by pressureless sintering and hot pressing. The reactions taking place in these systems were observed using the X-ray diffraction, infrared spectroscopy and dilatometric observations. It was confirmed that the extent of the reactions was essentially dependent on the heat treatment method. Under the hot pressing conditions dense samples containing high fraction of unreacted HAp could be prepared at 1200 °C. Mechanical properties of the pure HAp and HAp-ZrO2 composites were also investigated. Zirconia inclusions lead to the increased strength, hardness and fracture toughness of the composites compared to the pure HAp polycrystalline materials

Reference Electrodes with Polymer-Based Membranes—Comprehensive Performance Characteristics

Several types of liquid membrane and solid-state reference electrodes based on different plastics were fabricated. In the membranes studied, equitransferent organic (QB) and inorganic salts (KCl) are dispersed in polyvinyl chloride (PVC), polyurethane (PU), urea-formaldehyde resin (UF), polyvinyl acetate (PVA), as well as remelted KCl in order to show the matrix impact on the reference membranes&rsquo; behavior. The comparison of potentiometic performance was made using specially designed standardized testing protocols. A problem in the reference electrode research and literature has been a lack of standardized testing, which leads to difficulties in comparing different types, qualities, and properties of reference electrodes. Herein, several protocols were developed to test the electrodes&rsquo; performance with respect to stability over time, pH sensitivity, ionic strength, and various ionic species. All of the prepared reference electrodes performed well in at least some respect and would be suitable for certain applications as described in the text. Most of the reference types, however, demonstrated some weakness that had not been previously highlighted in the literature, due in large part to the lack of exhaustive and/or consistent testing protocols

Boron-Rich Boron Carbide Nanoparticles as a Carrier in Boron Neutron Capture Therapy: Their Influence on Tumor and Immune Phagocytic Cells

The aim of the work was to study the interaction between boron-rich boron carbide nanoparticles and selected tumor and immune phagocytic cells. Experiments were performed to investigate the feasibility of the application of boron carbide nanoparticles as a boron carrier in boron neutron capture therapy. Boron carbide powder was prepared by the direct reaction between boron and soot using the transport of reagents through the gas phase. The powder was ground, and a population of nanoparticles with an average particle size about 80 nm was selected by centrifugation. The aqueous suspension of the nanoparticles was functionalized with human immunoglobulins or FITC-labeled human immunoglobulins and was then added to the MC38 murine colon carcinoma and to the RAW 264.7 cell line of mouse macrophages. Flow cytometry analysis was used to determine interactions between the functionalized boron carbide nanoparticles and respective cells. It was shown that B4C–IgG nanoconjugates may bind to phagocytic cells to be internalized by them, at least partially, whereas such nanoconjugates can only slightly interact with molecules on the cancer cells’ surface