Production of meso- and giga-porous zirconia particles — An improved multi-step particle aggregation process

Macro- and giga-porous zirconia supports were prepared from a 20% colloidal sol of zirconia (ZrO₂) by a combination of a polymer-induced colloid aggregation (PICA) process and the oil emulsion (OE) method. The effect of the pH of the initial sol on the size of the PICA particles, and subsequently on the final product, made by oil-emulsion assisted aggregation of the PICA particles was thoroughly investigated. Both the PICA and the OE methods were further optimized for performance. Particle morphology and porosity of the resultant particles were characterized by scanning electron microscopy, mercury intrusion-extrusion porosimetry, and nitrogen adsorption-desorption sorptometry. The supports were comprised of stable aggregates of 50-250 μm in size. The pore and throat size distributions showed narrow bi-modal distributions over two distinct size scales: 10-100 nm and 600-3000 nm. In addition, different combinations of aggregation techniques and porous supports prepared in previous steps for use in a subsequent aggregation were evaluated. Optimal amounts of zirconia sol and 10-100 micron porous spherical particles produced by the OE method in an earlier step were combined in an additional OE process to yield stable giga-porous supports. Porous zirconia particles obtained after calcination and sintering had particle sizes of 0.15-3.5 mm and multimodal pore and throat distributions over a range of 50 nm-8 μm.     

Prediction of osteoconductive activity of modified potassium fluorrichterite glass-ceramics by immersion in simulated body fluid

Potassium fluorrichterite (KNaCaMg₅Si₈O₂₂F₂) glass-ceramics were modified by either increasing the concentration of calcium (GC5) or by the addition of P₂O₅ (GP2). The stoichiometric composition (GST), GC5 and GP2 were soaked in simulated body fluid (SBF) along with 45S5-type bioglass as a control. After immersion, surface analyses were performed using thin-film X-ray diffraction (TF-XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and Fourier-transform infrared (reflection) spectroscopy (FT-IR). All compositions showed the formation of a calcium phosphate rich surface layer in SBF; GST, GP2 and the bioglass control within 7 days of immersion and GC5 after 14 days. It was concluded that all compositions were likely to be osteoconductive in vivo, with GP2 providing the best performance in terms of the combination of rapid formation of the surface layer and superior mechanical properties. This glass-ceramic system has potential as a load bearing bioceramic for fabrication of medical devices intended for skeletal tissue repair.     

Bone-bonding properties of Ti metal subjected to acid and heat treatments

The effects of surface treatment on the bone-bonding properties of Ti metal were examined by both mechanical detaching test and histological observation after implantation into rabbit tibiae for various periods ranging from?4 to?26?weeks. The bone-bonding ability of Ti metal, which is extremely low as it is abraded, was hardly increased by simple heat treatment at 600?°C or treatment with H₂SO₄/HCl mixed acid alone, but was markedly increased by the heat treatment after the acid treatment. Even Ti metal that had been previously subjected to NaOH treatment showed considerably high bone-bonding ability after acid and heat treatments. Such high bonding abilities were attributed to their high apatite-forming ability in the body environment. Their high apatite-forming abilities were attributed to a high positive surface charge, and not to the type of crystalline phase or specific roughness of their surfaces. The present study has demonstrated that acid and subsequent heat treatments are effective for conferring stable fixation properties on Ti metal implants.     

Apatite-forming ability of titanium in terms of pH of the exposed solution

In order to elucidate the main factor governing the capacity for apatite formation of titanium (Ti), Ti was exposed to HCl or NaOH solutions with different pH values ranging from approximately 0 to 14 and then heat-treated at 600°C. Apatite formed on the metal surface in a simulated body fluid, when Ti was exposed to solutions with a pH less than 1.1 or higher than 13.6, while no apatite formed upon exposure to solutions with an intermediate pH value. The apatite formation on Ti exposed to strongly acidic or alkaline solutions is attributed to the magnitude of the positive or negative surface charge, respectively, while the absence of apatite formation at an intermediate pH is attributed to its neutral surface charge. The positive or negative surface charge was produced by the effect of either the acidic or alkaline ions on Ti, respectively. It is predicted from the present results that the bone bonding of Ti depends upon the pH of the solution to which it is exposed, i.e. Ti forms a bone-like apatite on its surface in the living body and bonds to living bone through the apatite layer upon heat treatment after exposure to a strongly acidic or alkaline solution.     

Comparative Proteomic Profiling of Secreted Extracellular Vesicles from Breast Fibroadenoma and Malignant Lesions: A Pilot Study

Extracellular vesicles (EVs) shuttle proteins, RNA, DNA, and lipids crucial for cell-to-cell communication. Recent findings have highlighted that EVs, by virtue of their cargo, may also contribute to breast cancer (BC) growth and metastatic dissemination. Indeed, EVs are gaining great interest as non-invasive cancer biomarkers. However, little is known about the biological and physical properties of EVs from malignant BC lesions, and even less is understood about EVs from non-malignant lesions, such as breast fibroadenoma (FAD), which are clinically managed using conservative approaches. Thus, for this pilot study, we attempted to purify and explore the proteomic profiles of EVs from benign breast lesions, HER2+ BCs, triple–negative BCs (TNBCs), and continuous BC cell lines (i.e., BT-549, MCF–10A, and MDA-MB-231), combining experimental and semi-quantitative approaches. Of note, proteome-wide analyses showed 49 common proteins across EVs harvested from FAD, HER2+ BCs, TNBCs, and model BC lines. This is the first feasibility study evaluating the physicochemical composition and proteome of EVs from benign breast cells and primary and immortalized BC cells. Our preliminary results hold promise for possible implications in precision medicine for BC.     

Structural,Electrical, and Optical Behavior of Strontium Bismuth Titanate Ceramic

In this report, we present the structural, electrical, and optical study of layer-structured SrBi₄Ti₄O₁₅ (SBT) ceramic prepared by solid-state reaction route. The X-ray diffraction and Rietveld refinement studies show a single-phase orthorhombic structure with space group A₂₁am. The scanning electron micrograph shows plate-like grains. The various Raman peaks originated due to the TiO₆ octahedron confirm the orthorhombic structure. The temperature-dependent dielectric study shows a normal ferroelectric phase transition with a transition temperature at 813 K (540 °C). Impedance studies show a non-Debye-type relaxation and relaxation frequency shift to higher side with increase in temperature. The Nyquist plot shows overlapping semicircles which results the existence of both for grain and grain boundary effect in SBT ceramic. The frequency-dependent AC conductivity at different temperatures indicates that the conduction process is thermally activated and the spectra follow the universal power law. The variation of DC conductivity confirms that the SBT ceramic exhibits negative temperature coefficient of resistance behavior. The Ferroelectric behavior is studied by hysteresis loop. The optical band gap is found to be 2.93 eV from the UV–Visible spectroscopy study. The room-temperature photoluminescence study shows a strong red emission.     

Interaction between monolithic, junction-isolated lateralinsulated-gate bipolar transistors

The static and dynamic interaction between monolithically integrated n- and p-channel, high-voltage lateral insulated-gate bipolar transistors (LGBTs) are studied. In the chosen system partition, three common-source, n-channel LIBGTs are monolithically integrated on one chip using junction isolation, while the p-channel counterparts are on a separate chip. Devices on lightly doped substrates, despite their higher forward drop and longer turn-off time than those on heavily doped substrates, exhibited a lesser degree of interaction with adjacent devices, and thus are preferable for power ICs. Even though the steady-state current that flows into the emitters of adjacent devices in the ON-state is small (<5%), there are substantial (as much as 40%) current surges during the turn-on and turn-off transients. Also, the emitter areas also act as minority-carrier injectors during the last phase of the turn-off process. Similar observations are made on LIGBTs with collector shorts and hybrid Schottky injection field-effect transistors (HSINFETs), despite their faster turn-off times