The corrosion resistance of titanium and its alloys is a desirable property for many applications in materials science. In this report, the properties of the passive oxide film (TiO2) were examined by scanning electrochemical microscopy (SECM). A homemade closed-loop scanning electrochemical microscope was used to study these properties at the micrometer scale using ferrocenemethanol (Fc) as the redox mediator. The experimental results showed that the passive properties of a well-polished ASTM Grade-2 titanium (Ti-2) sample differed from region to region as indicated by the different current responses of the ultramicroelectrode (UME) on the SECM images. Selected spots with high feedback tip current were examined more closely by additional scanning. It was concluded that active spots with high positive feedback current were indicative of reactive structures located along crystalline grain boundaries, especially at the triple points. This observation is confirmed by comparing SECM results with optical micrographs reported in the literature. Previous metallographic investigations show these are the sites where the impurity iron content of the alloy congregates. This is confirmed by our experiments on scanning electron microscopy and energy dispersive X-ray analysis. For the first time, grain microstructure maps have been constructed on the SECM images, based on the above active sites. The properties of TiO2 films on Ti-2 were also assessed at various applied potentials. The reactivity of the oxide-covered Ti-2 surface increased and more active spots appeared when the Ti-2 bias potential was made more negative. This was attributed to oxide reduction (Ti(IV) to Ti(III)) and the onset of the absorption of hydrogen. The potential at which this change occurred varied at different sites on the scale of the grain structure (20−100 μm). These results demonstrate that SECM is a noninvasive analytical methodology that can provide insights into the structures and reactivities of Ti-2.

With the proposed Canadian July 2018 legalization of marijuana through the Cannabis Act, a thorough critical analysis of the current trials on the efficacy of medicinal marijuana (MM) as a treatment option is necessary. This review is particularly important for primary care physicians whose patients may be interested in using MM as an alternative therapy. In response to increased interest in MM, Health Canada released a document in 2013 for general practitioners (GPs) as an educational tool on the efficacy of MM in treating some chronic and acute conditions. Although additional studies have filled in some of the gaps since the release of the Health Canada document, conflicting and inconclusive results continue to pose a challenge for physicians. This review aims to supplement the Health Canada document by providing physicians with a critical yet concise update on the recent advancements made regarding the efficacy of MM as a potential therapeutic option. An update to the literature of 2013 is important given the upcoming changes in legislation on the use of marijuana. Also, we briefly highlight the current recommendations provided by Canadian medical colleges on the parameters that need to be considered prior to authorizing MM use, routes of administration as well as a general overview of the endocannabinoid system as it pertains to cannabis. Lastly, we outline the appropriate medical conditions for which the authorization of MM may present as a practical alternative option in improving patient outcomes as well as individual considerations of which GPs should be mindful. The purpose of this paper is to offer physicians an educational tool that provides a necessary, evidence-based analysis of the therapeutic potential of MM and to ensure physicians are making decisions on the therapeutic use of MM in good faith.

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Hydrogen absorption by Zircaloy-2 has been studied in neutral sodium sulfate solutions using steady-state polarization measurements, electrochemical impedance spectroscopy (EIS), and scanning electrochemical microscopy (SECM). For applied potentials < −1 V (vs. saturated calomel electrode, SCE), water reduction occurs in faults in the passive oxide covering the alloy. For potentials ≤−1.3 V SCE , SECM detects a distribution of reactive locations on the electrode surface. Matched SECM and SEM images of the same electrode surface show more reactive sites to be located in the β-phase grain boundaries than on the α-grains. The reactivity of surface locations was determined using SECM probe approach curves. Secondary phase particles incorporating impurities such as Fe, Ni, and Cr as Zr(Fe, Cr) 2 and Zr 2 (Fe, Ni) are particularly reactive spots, which may act as "windows" for hydrogen absorption into the alloy. This claim is supported by the observation that the surface of the α-grains remains passive even at potentials as low as −2.0 V SCE . The need to include a Warburg impedance element in modeling EIS recorded at potentials ≥−1.3 V SCE suggests that H 2 O reduction is confined to tight flaws in the oxide at grain boundary locations.