Synchrotron X‐ray CT characterization of titanium parts fabricated by additive manufacturing. Part II. Defects

Synchrotron X‐ray tomography (SXRT) has been applied to the study of defects within three‐dimensional printed titanium parts. These parts were made using the Arcam EBM^® (electron beam melting) process which uses powdered titanium alloy, Ti64 (Ti alloy with approximately 6%Al and 4%V) as the feed and an electron beam for the sintering/welding. The experiment was conducted on the Imaging and Medical Beamline of the Australian Synchrotron. The samples represent a selection of complex shapes with a variety of internal morphologies. Inspection via SXRT has revealed a number of defects which may not otherwise have been seen. The location and nature of such defects combined with detailed knowledge of the process conditions can contribute to understanding the interplay between design and manufacturing strategy. This fundamental understanding may subsequently be incorporated into process modelling, prediction of properties and the development of robust methodologies for the production of defect‐free parts.     

Probiotics in Cosmetic and Personal Care Products: Trends and Challenges

Probiotics, defined as “live microorganisms that, when administered in adequate amounts, confer a health benefit on the host,” are becoming increasingly popular and marketable. However, too many of the products currently labelled as probiotics fail to comply with the defining characteristics. In recent years, the cosmetic industry has increased the number of products classified as probiotics. While there are several potential applications for probiotics in personal care products, specifically for oral, skin, and intimate care, proper regulation of the labelling and marketing standards is still required to guarantee that consumers are indeed purchasing a probiotic product. This review explores the current market, regulatory aspects, and potential applications of probiotics in the personal care industry.     

A Study of the Fracture of Pellets Fired Against a Target

Pellets of sintered Al₂O₃ of approximately 3 mm diameter and length were broken in the Brazilian mode and the distribution of strength obtained. It was found that there was also a distribution of Young's modulus E. Hertzian theory implies that the maximum impact force of a pellet fired against a rigid target would depend on E. However, since the pellets can strike in different geometries there is a distribution of impact force for a fixed E. Comparison of theory with data obtained with a force-time transducer as the target showed that the major variation of maximum recorded force could be assigned to the variation of E. The median of the maximum recorded force varied with velocity as v^6/5, implying that the pellets behaved approximately as impacting spheres. An attempt was made to predict the probability of breakage in one impact from convoluting the distribution of impact force with the strength distribution from the Brazilian test converted to the equivalent strength distribution expected for impacting spheres. This gave the correct order of magnitude but did not accurately predict the experimental values.     

Identification of individual tetra- and pentacyclic naphthenic acids in oil sands process water by comprehensive two-dimensional gas chromatography/mass spectrometry

The oils sands industry of Canada produces large volumes of process water (OSPW) which is stored in large lagoons. The OSPW contains complex mixtures of somewhat toxic, water-soluble, acid-extractable organic matter sometimes called 'naphthenic acids' (NA). Concerns have been raised over the possible environmental impacts of leakage of OSPW and a need has therefore arisen for better characterisation of the NA. Recently, we reported the first identification of numerous individual tricyclic NA in OSPW by comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GCxGC/ToF-MS) of the methyl esters. The acids were diamondoid adamantane acids, resulting, it was proposed, from biotransformation of the corresponding alkyladamantane hydrocarbons, which is a known process. Biotransformation of higher alkylated diamondoid hydrocarbons was, until now, unknown but here we describe the identification of numerous pentacyclic NA as diamantane and alkyldiamantane acids, using the same methods. Further, we suggest tentative structures for some of the tetracyclic acids formed, we propose, by ring-opening of alkyldiamantanes. We suggest that this is further evidence that some of the acid-extractable organic matter in the OSPW originates from extensive biodegradation of the oil, whether in-reservoir or environmental, although other oxidative routes (e.g. processing) may also be possible. The results may be important for helping to better focus reclamation and remediation strategies for NA and for facilitating the identification of the sources of NA in contaminated environmental samples.     

PRODUCTION OF PIGMENT NANOPARTICLES USING A WET STIRRED MILL WITH POLYMERIC MEDIA

Pigment nanoparticles with a size range of 10-100 nm were produced from large agglonmerates via a stirred media mill operating in the wet-batch mode and using polymeric media,The effects of several operating variables such as the surfactant concentration,polystyrene media loading.and media size on the pigment size distribution of the product were studied.The process dynamics was also investigated.Dynamic light scattering and electron microscopy were used as the characerization techniques.The polymeric grinding media are found to be effective for the production of pigment nanoparticles.The experimental results suggest the existence of an optimum media size and surfactant concentration,A population balance model of the process reveals a transition from first-order breakage kinetice for rela-large agglomerates split in a first-order kinetics,with a delay period,for the smaller particles.The model implies that large agglomerates split in a first-order fashion whereas the breakage of individual naoparticles may depend on induced fatigue of the particles.