Effects of composition and phase relations on mechanical properties and crystallisation of silicate glasses

Crystallization, mechanical properties and workability are all important for commercialization and optimization of silicate glass compositions. However, the inter-relations of these properties as a function of glass composition have received little investigation. Soda-lime-silica glasses with Na2O-MgO-CaO-Al2O3-SiO2 compositions relevant to commercial glass manufacture were experimentally studied and multiple liquidus temperature and viscosity models were used to complement the experimental results. Liquidus temperatures of the fabricated glasses were measured by the temperature gradient technique, and Rietveld refinements were applied to X-Ray powder diffraction (XRD) data for devitrified glasses, enabling quantitative determination of the crystalline and amorphous fractions and the nature of the crystals. Structural properties were investigated by Raman spectroscopy. Acoustic echography, micro-Vicker’s indentation and single-edge notched bend testing methods were used to measure Young’s moduli, hardness and fracture toughness, respectively. It is shown that it is possible to design lower-melting soda-lime-silica glass compositions without compromising their mechanical and crystallization properties. Unlike Young’s modulus, brittleness is highly responsive to the composition in soda-lime-silica glasses, and notably low brittleness values can be obtained in glasses with compositions in the wollastonite primary phase field: an effect that is more pronounced in the silica primary phase field. The measured bulk crystal fractions of the glasses subjected to devitrification at the lowest possible industrial conditioning temperatures, indicate that soda-lime-silica glass melts can be conditioned close to their liquidus temperatures within the compositional ranges of the primary phase fields of cristobalite, wollastonite or their combinations

Assessment of web crippling design provisions for application to proprietary soldier beams

Structures used for temporary works are lightweight so that they are easy to transport, erect and dismantle. Particular care should be taken in their design as local instabilities could arise due to their thin-walled nature. This article presents 12 tests on proprietary soldier beams subjected to two concentrate opposing loads applied simultaneously. The geometry of the proprietary beams feature cold-formed C-shaped sections with web holes connected back to back with internal spacers. In the absence of design rules for application to such members, the experimental results are used in the present investigation to assess the suitability of the provisions for the web crippling design of coldformed steel members as well as existing design methods from the literature, which account for the effect of perforations in the web. Experimental and predicted resistances are compared and design recommendations are provided.Leada Acro

Intravesical device-assisted therapies for non-muscle-invasive bladder cancer

Non-muscle-invasive bladder cancer (NMIBC), the most prevalent type of bladder cancer, accounts for ~75% of bladder cancer diagnoses. This disease has a 50% risk of recurrence and 20% risk of progression within 5 years, despite the use of intravesical adjuvant treatments (such as BCG or mitomycin C) that are recommended by clinical guidelines. Intravesical device-assisted therapies, such as radiofrequency-induced thermochemotherapeutic effect (RITE), conductive hyperthermic chemotherapy, and electromotive drug administration (EMDA), have shown promising efficacy. These device-assisted treatments are an attractive alternative to BCG, as issues with supply have been a problem in some countries. RITE might be an effective treatment option for some patients who have experienced BCG failure and are not candidates for radical cystectomy. Data from trials using EMDA suggest that it is effective in high-risk disease but requires further validation, and results of randomized trials are eagerly awaited for conductive hyperthermic chemotherapy. Considerable heterogeneity in patient cohorts, treatment sessions, use of maintenance regimens, and single-arm study design makes it difficult to draw solid conclusions, although randomized controlled trials have been reported for RITE and EMDA

Particulate Matter in the Hospital Environment

Investigations of particle concentration levels and size distribution were conducted in the complex hospital system of the Royal Children’s and the Royal Brisbane Hospitals. The aim of the measurements was to provide an indication of particulate sources in the hospital environment and relate particle characteristics to the operating parameters of the hospitals. The measurements were performed using the most advanced instrumentation for size classification in the submicrometer and supermicrometer levels. The conclusions from the investigation were (i) that indoor concentration levels of particle numbers are closely related to outdoor concentration levels, indicating that outdoor particulates were the main contributor to the indoor particulates in the hospitals under investigations and (ii) that the performance of filtration/ventilation systems is the most critical parameter in reducing general particulate concentration levels in those hospital units where medical procedures can result in generation of potentially hazardous organic aerosols