Release of Nanoparticles in the Environment and Catalytic Converters Ageing

A Three-Way Catalyst (TWC) contains a cordierite ceramic monolith coated with a layer of Al2O3, CexZr1−xO2 and platinoids mixture. Under standard operation, the platinoid concentration decreases, exposing the remaining washcoat structure. After that particle release stage, the sintering process follows where the crystalline CexZr1−xO2 solution is broken and begins to separate into ZrO2 and CeO2 phases. ZrO2 is released to the environment as micro and nanoparticles, while a small amount of CeO2 generates a new AlxCe1−xO2 composite. The main effect of Ce capture is the growth in the size of the polycrystal structure from 86.13 ± 16.58 nm to 225.35 ± 69.51 nm. Moreover, a transformation of cordierite to mullite was identified by XRD analysis. Raman spectra showed that the oxygen vacancies (Vö) concentration decreased as CexZr1−xO2 phases separation occurred. The SEM-EDS revealed the incorporation of new spurious elements and microfractures favouring the detachment of the TWC support structure. The release of ultrafine particles is a consequence of catalytic devices overusing. The emission of refractory micro to nanocrystals to the atmosphere may represent an emerging public health issue underlining the importance of implementing strict worldwide regulations on regular TWCs replacement.

Method to determine particle release during long-term loading for assessment of coating durability of cardiovascular stents

Many catheters and vascular implants are coated to increase biocompatibility or to reduce friction during catheter based implantation. Several regulations require assessment of coating durability over the implant’s life time. An in vitro method for stent testing is presented to measure released particulate matter at defined inspection intervals. The method was validated using polystyrene microspheres with a size of 10, 25 and 50 μm to check for particle recovery (n=6). Two cleaning steps followed. Particle counting was performed by light obscuration method. The recovery rate was 103±5% (10μm), 94±4% (25 μm) and 78±12% (50 μm), respectively, meeting the requirements of FDA guidance documents (i.e. FDA 1545). Less than 3% of the particles were found in the cleaning solutions. The method using a fixed volume during stent loading can be adapted to all durability testers where tubes are used to fix the stents (radial pulsatile, bending, axial compression, torsion).

Lower temperature influences Cauliflower mosaic virus systemic infection

Lower temperatures delayed development of systemic symptoms by Cauliflower mosaic virus (CaMV) in two different plant hosts. However, lower temperature exposure increased CaMV nucleic acid levels in leaves of systemically-infected turnips. Furthermore, lower temperature altered the formation of aggregates formed by the CaMV major inclusion body (IB) protein, P6. Finally, lower temperature altered the architecture of the actin cytoskeleton. These data may suggest that lower temperatures alter the actin cytoskeleton, facilitating the formation of larger IBs that hold on to their internal virions more strongly than small ones, impairing virus particle release and causing a delay in systemic infection.

High particle variability across siliconized and oil-free syringes and needles from the same lots

Previous studies have reported silicone oil (SO) applied to needles and syringes in the vitreous of patients after intravitreal injections. We evaluated four syringes (SR 1-mL insulin, Saldanha-Rodrigues; BD 1-mL Tuberculin Slip Tip, Becton–Dickinson; BD Ultra-Fine 0.3 mL, HSW Norm-Ject Tuberculin, Henke Sass Wolf) and 10 needles (BD PrecisionGlide 27- and 30-gauge (G); BD Eclipse and JBP Nanoneedle 27-, 30-, 33- and 34-G; TSK Invisible Needle and 27 and 30-G Steriject Control Hub). The protein-free buffer samples injected into the syringes and needles under study were collected in an Eppendorf tube and taken to Flow imaging microscopy, that characterized the concentration and morphology of the microsized particles. The number of particles was analyzed. The coefficients of variation (CV) were the primary outcome. The Feltz and Miller test compared the CVs. The significance level was 5%. Numerous particles and high CVs were associated with both devices, needles and syringes; the comparisons among them did not reach significance. The BD Ultrafine 0.3 mL syringe (149.7%) had the highest CV and the SO-free HSW Norm-Ject (66.4%) syringe the lowest, and the TSK Invisible needle (149.5%) had the highest and the BD Precision Glide 30G needle (35.9%) needle the lowest. In conclusion, particle release, including those with SO morphology, varied greatly among instruments, even from the same lots, which is relevant considering that fewer particles are injected into some eyes compared with others.