Surface silver-doping of biocompatible glasses to induce antibacterial properties. Part II: plasma sprayed glass-coatings

A 57% SiO₂, 3% Al₂O₃, 34% CaO and 6% Na₂O glass (SCNA) has been produced in form of powders and deposited by plasma spray on titanium alloy and stainless steel substrates. The obtained coatings have been subjected to a patented ion-exchange treatment to introduce silver ions in the surface inducing an antibacterial behavior. Silver surface-enriched samples have been characterized by means of X-ray diffraction, SEM observation, EDS analysis, in vitro bioactivity tests, leaching tests by GFAAS (graphite furnace atomic adsorption spectroscopy) analyses, cells adhesion and proliferation, and antibacterial tests using Staphylococcus Aureus strain. In vitro tests results showed that the modified samples acquired an antimicrobial action against tested bacteria maintaining unaffected the biocompatibility of the glass. Furthermore the ion-exchange treatment can be successfully applied to glass-coated samples without affecting the properties of the coatings; the simplicity and reproducibility of the method make it suitable for glass or glass-ceramic coatings of different composition in order to produce coated devices for bone healing and/or prostheses, able to reduce bacterial colonization and infections risks.     

Recent ground subsidence at Crown Road,Tauhara and its probable causes

A localised ground subsidence anomaly at Crown Road, Taupo, within the Tauhara field of the Wairakei–Tauhara geothermal system, has been subjected to intense scrutiny because of its relatively recent onset and proximity to urban areas. Over a period of 20 years a maximum of 0.63 m of subsidence has accumulated. Uncertainties regarding its cause remain, but the evidence now strongly favours a relatively shallow (about 50 m depth) origin, compared with other geothermal subsidence bowls at Wairakei, Tauhara and Ohaaki. Declining water levels in a shallow boiling aquifer are considered to be the principal driving mechanism at Crown Road. The source of the subsidence is an anomalously compressible formation of intensely altered ignimbrite found at the base of a buried hydrothermal eruption deposit. This formation is dominated by soft kaolinite and smectite-illite clays of high plasticity and water content, resulting from alteration of highly vesiculated pumice, and is capped by a thin hardpan of silicified pyroclastic material, characterised by vuggy macro-porosity, at about 33 m depth. During initiation of the subsidence event, this hardpan may have failed in shear mode around the edges of a buried eruption crater, allowing the overburden to fully load the underlying compressible clays.     

Combining Magnetic Resonance Imaging with Systemic Monocyte Evaluation for the Implementation of GBM Management

Magnetic resonance imaging (MRI) is the gold standard for glioblastoma (GBM) patient evaluation. Additional non-invasive diagnostic modalities are needed. GBM is heavily infiltrated with tumor-associated macrophages (TAMs) that can be found in peripheral blood. FKBP51s supports alternative-macrophage polarization. Herein, we assessed FKBP51s expression in circulating monocytes from 14 GBM patients. The M2 monocyte phenotype was investigated by qPCR and flow cytometry using antibodies against PD-L1, CD163, FKBP51s, and CD14. MRI assessed morphologic features of the tumors that were aligned to flow cytometry data. PD-L1 expression on circulating monocytes correlated with MRI tumor necrosis score. A wider expansion in circulating CD163/monocytes was measured. These monocytes resulted in a dramatic decrease in patients with an MRI diagnosis of complete but not partial surgical removal of the tumor. Importantly, in patients with residual tumor, most of the peripheral monocytes that in the preoperative stage were CD163/FKBP51s− had turned into CD163/FKBP51s+. After Stupp therapy, CD163/FKBP51s+ monocytes were almost absent in a case of pseudoprogression, while two patients with stable or true disease progression showed sustained levels in such circulating monocytes. Our work provides preliminary but meaningful and novel results that deserve to be confirmed in a larger patient cohort, in support of potential usefulness in GBM monitoring of CD163/FKBP51s/CD14 immunophenotype in adjunct to MRI.     

Ceramic-on-ceramic catastrophic liner failure in total hip arthroplasty: Morphological and compositional analysis of fractured ceramic components

Surface bearing of total hip arthroplasty (THA) still is a strong subject of study due to the relatively high rate of failures caused by a multiplicity of factors including surgical technique, patient's attitude, and type/characteristics of the materials used (metal, ceramics, polyethylene) with their specific risk factors. Fractures of the ceramic components are rare but catastrophic events, with many concerns among the orthopaedic surgeons. Such complication is usually evaluated from a clinical viewpoint; this study provides a materials scientist's complementary perspective and comprehensively evaluates the surface and the mechanism of rupture of the ceramic liner in two cases with different ceramics (Biolox Forte and Biolox Delta) after ceramic-on-ceramic THA. The morphological and compositional analyses of the ceramic components were performed by field-emission scanning electron microscopy (FESEM) and energy dispersive spectroscopy (EDS), along with macroscopic pictures. The SEM analysis of the ceramic liner showed many wear signs in all directions, while the EDS revealed the presence of titanium near to the fracture border, which might be interpreted as a consequence of the catastrophic contact between ceramic liner and metal back. Biolox Delta and Biolox Forte ceramic liners showed different patterns of fracture and surface modifications that are illustrated and discussed.     

Pores occlusion in MCM-41 spheres immersed in SBF and the effect on ibuprofen delivery kinetics: A quantitative model

MCM-41 silica particles have been synthesized with size in the low submicron range, loaded with ibuprofen and characterized by means of XRD, N₂ adsorption and scanning electron microscopy, coupled with EDS analysis both before and after contact with different volumes of simulated body fluid (SBF) at 37 °C up to 10 h.The particles do not show any change in morphology, composition and mesostructure as a consequence of soaking. MCM-41 spheres, though, are not inert towards SBF. Two processes take place, showing features independent from the soaking volume: (i) one within 1–2 h, bringing about dissolution of silica into the liquid phase up to a concentration of 2.2 mM and no change in the mesopore volume; (ii) the second, after an induction period of 1–2 h, bringing about a limited increase in the concentration of dissolved silica, but affecting severely the mesoporous volume, which decreases exponentially with time.Delivery curves differ significantly when varying the volume of SBF used. To account for release kinetics under the circumstances observed, a mathematical model is proposed, based on the standard Noyes–Whitney equation, taking into account both the SBF volume used and the mesopores occlusion, this latter through a time-dependent diffusion coefficient. A satisfactory agreement is observed, without the intervention of any adjustable parameter.     

Wire bonding characteristics of gold conductors for low temperature co-fired ceramic applications

Low temperature co-fired ceramic (LTCC) with gold conductors has been used for high reliability applications, such as satellite communications. When the gold metallization is co-fired with the LTCC tape, inorganic adhesion additives in the gold conductor interact with the LTCC glass. This interaction is essential to provide adequate adhesion for the gold metallization. However, this interaction can also reduce the softening point of the LTCC glass. The reaction product can migrate to the surface of the gold conductor and affect the wire bondability of the gold conductor.Effort has been made to develop surface gold conductors with optimized interaction with LTCC. The new gold conductor shows significant reduction of inorganic particles on the surface and improvement of wire bondability. A systematic wire bonding study has been performed on gold conductors under various wire bonding conditions. It is demonstrated that the wire bonding window can be improved significantly by reducing the interaction between LTCC and gold metallization. This paper reports the results of the wire bonding study.     

Flow cytometry analysis of drug transport mechanisms in Haemonchus contortus susceptible or resistant to anthelmintics

The role of membrane drug-transport mechanisms in resistance to anthelmintics was examined using a flow cytometry method. This method was adapted from assays developed for the study of similar mechanisms in tumor cells. Rhodamine 123, a P-glycoprotein transport probe, associated with the reversal agent verapamil gave a significantly higher level of green fluorescence in Haemonchus contortus-resistant eggs as compared with that of susceptible eggs. In the same way, verapamilbodipy, a new fluorescent probe for the detection of multidrug resistance in cells, showed a significantly higher degree of binding to resistant eggs. The results confirm those obtained with biological drug assays using both anthelmintics and verapamil and provide a quantitative and effective methodology for the functional study of multidrug resistance in nematodes.