The CO2 huff-n-puff process offers dual benefits by enhancing bitumen recovery while contributing to carbon capture, utilization, and storage. This study investigates the evolution and stability of CO2 gas bubbles during the puff stage and their contribution to the volumetric expansion of foamy bitumen under reservoir-relevant temperatures. Experiments were conducted in a high-pressure vessel, where pure CO2 was injected into bitumen samples and allowed to dissolve under controlled conditions during the huff stage. Upon reaching quasi-dynamic equilibrium, the system was rapidly depressurized to atmospheric pressure to initiate the puff stage. Bubble evolution was recorded and analyzed using image-based techniques. Four key parameters of bubbles: half-life, size, number, and circularity, that characterize bubble evolution and stability, were quantified and compared across all conditions. The results reveal two distinct temperature-dependent regimes: a low-temperature regime (25 and 35 °C) and a high-temperature regime (45 and 55 °C). Lower temperatures and higher pressures generally produced smaller, more uniform, and longer-lived bubbles, leading to enhanced foam stability and higher expansion factors. In contrast, higher temperatures produced larger, short-lived bubbles and reduced foam stability. Among all parameters, bubble half-life and bubble size (particularly median bubble size) emerge as the most reliable indicators of bubble stability and foam expansion, whereas bubble number and circularity provide supplementary information on bubble dynamics and morphology. These findings provide new insight into CO2–bitumen interactions during the puff stage and clarify the role of bubble stability in governing foamy bitumen behavior under non-thermal conditions.
The transition to non-platinum group metal (PGM) electrocatalysts for the oxygen reduction reaction (ORR) in polymer electrolyte fuel cells (PEFCs) is central to achieving sustainable and cost-effective energy conversion. However, the continued widespread use of platinum counter electrodes in electrochemical testing introduces a critical artefact, namely, platinum dissolution, migration through the electrolyte and redeposition onto the working electrode. This potentially skews performance metrics and undermines claims of ‘platinum-free’ sustained ORR activity. This study systematically investigates this issue using a model nitrogen-doped carbon electrocatalyst with inherently low catalytic activity, allowing facile observation of small performance improvements that may be difficult to separate in high-performance catalysts. Platinum wire and graphite rod counter electrodes are compared under load cycling and start-stop conditions in both acidic and alkaline media over 60,000 potential cycles. We demonstrate that platinum contamination from the counter electrode significantly enhances ORR activity and slows performance degradation, effects which are absent when a graphite counter electrode is used. Transmission electron microscopy (TEM) confirms platinum electrodeposition on the working electrode. These findings challenge prevailing experimental protocols and establish the graphite counter electrode as essential for accurate benchmarking of non-PGM catalysts. The work delivers a clear methodological clarification with broad implications for electrocatalyst development and validation.
The transition to non-platinum group metal (PGM) electrocatalysts for the oxygen reduction reaction (ORR) in polymer electrolyte fuel cells (PEFCs) is central to achieving sustainable and cost-effective energy conversion. However, the continued widespread use of platinum counter electrodes in electrochemical testing introduces a critical artefact, namely, platinum dissolution, migration through the electrolyte and redeposition onto the working electrode. This potentially skews performance metrics and undermines claims of 'platinum-free' sustained ORR activity. This study systematically investigates this issue using a model nitrogen-doped carbon electrocatalyst with inherently low catalytic activity, allowing facile observation of small performance improvements that may be difficult to separate in highperformance catalysts. Platinum wire and graphite rod counter electrodes are compared under load cycling and start-stop conditions in both acidic and alkaline media over 60,000 potential cycles. We demonstrate that platinum contamination from the counter electrode significantly enhances ORR activity and slows performance degradation, effects which are absent when a graphite counter electrode is used. Transmission electron microscopy (TEM) confirms platinum electrodeposition on the working electrode. These findings challenge prevailing experimental protocols and establish the graphite counter electrode as essential for accurate benchmarking of non-PGM catalysts. The work delivers a clear methodological clarification with broad implications for electrocatalyst development and validation.
Food-derived peptides are gaining increasing attention for their brain-beneficial potential in alleviating central nervous system diseases. Although accumulating evidence indicates neuroprotective and cognitive-enhancing properties of peptides, the precise mechanisms of action remain insufficiently understood, creating challenges for their screening, identification, and application. A major limitation is the blood-brain barrier (BBB) system, which restricts the bioavailability of peptides to the brain. In this review, current advances on food-derived peptides with brain-beneficial effects are discussed, focusing on their roles in neurotransmitter modulation, neuroprotection, anti-inflammation, anti-amyloid-beta activity, and regulation of the gut-brain axis. We also discuss the peptides with brain-beneficial effects that are capable of crossing the BBB, as well as the experimental approaches used to assess their BBB permeability. Understanding both the functional actions and transport mechanisms of food-derived peptides will provide valuable insights for their application as nutraceuticals or therapeutic candidates for neurodegenerative diseases such as Alzheimer's disease.
