Towards multiscale X-ray tomographic imaging in membrane science : A perspective

Tomographic X-ray imaging techniques offer novel opportunities for studying membranes and membrane processes in 3D on a spatial resolution not seen before. Traditional 2D imaging techniques used to characterise membranes have limitations that can be overcome by tomographic X-ray imaging. Tomographic X-ray imaging can provide information in 2D/3D or 4D (3D plus time) on membranes, membrane modules, and membrane processes on a scale ranging from micro- to nanometre. They offer the possibility to uncover many fundamental issues related to membrane science, including the detection and monitoring of macroscopic biofilm formation, scaling, and cake build-up. High-resolution nanotomographic X-ray imaging enables even microscopic characterisations such as pore size distribution or pore network analysis. This Perspective paper introduces the tomographic X-ray imaging techniques with the most potential for membrane science: microtomography, nanotomography, holotomography, and ptychotomography, and presents their applications in the literature regarding the field of membrane science. Based on these findings and our experiences opportunities, challenges, and limitations of tomographic X-ray imaging techniques are discussed. It is concluded that in the near future tomographic X-ray imaging techniques will become increasingly common analytical techniques for membrane manufacturers, scientists, and users

The successful use of a search strategy improves with visuospatial working memory in 2- to 4.5-year-olds

Using spatial cues such as shape, orientation, and pattern aids visuospatial working memory because it allows strategies that reduce the load on this cognitive resource. One such strategy, namely taking advantage of patterned spatial distributions, remains understudied to date. This strategy demands keeping track of already-searched locations and excluding them from further search and so correlates with visuospatial working memory. The use of such strategies should, in principle, develop in early childhood, but because most studies focus on chunking, the development of other strategies reducing the load on working memory is understudied in young children. Therefore, in this study we tested whether children aged 2 to 4.5 years (N = 97) could take advantage of spatial cues in their search and whether this ability correlated with their age, verbal ability, and visuospatial working memory. The results showed that the ability to use a patterned spatial distribution (searching a row of locations from one side to the other instead of a random search) significantly improved with visuospatial working memory but not with age or verbal ability. These results suggest that visuospatial abilities may rapidly develop from 2 to 4.5 years of age, and given their impact on later mathematic achievement, demand increased attention in cognitive developmental research and early childhood education

A novel approach to the investigation and quantification of the stop/start process for pedestrian traffic using motion capture devices

Characterising the stop/start walking process of individuals in a crowded and congested space is an important consideration in modelling pedestrian movement. However, the reaction of pedestrians to speed changes, especially to the person in front, has not been fully characterised nor quantified for full adoption in computer models. This study, therefore, explored the different phases of the stop/start process through a series of novel experiments conducted at University College Dublin (UCD) in which individual movements were captured precisely using motion capture equipment. The overall aim of the study was to develop a novel methodology (inspired from vehicle traffic flow) to break down and quantify the components of the stop/start walking process, i.e., the perception-reaction time, slow-down time, and start-up time of individuals walking in a single-file. These times, together with the total stopping distance and inter-person distances of each follower to their leader at the beginning and the end of each phase were quantified successfully and their inter-relationships were explored. The results showed the mean perception-reaction time, slow-down time, and start-up time delay were 0.48, 0.58, and 0.39 s, respectively. Where applicable, normal, lognormal, Weibull, gamma, and log-logistic probability distributions were fitted to the data to determine the best fit. The novel methodology developed in this study can be used in the future to investigate pedestrians’ behaviour in response to any changes in leaders’ speed, i.e. quantify the reaction of individuals in different phases. The results of this study can inform the representation of the stop/start process in microscopic pedestrian models

Association of polypharmacy with occurrence of loneliness and social isolation among older adults

BackgroundPolypharmacy is increasing. The longitudinal association of polypharmacy and social isolation has not been previously reported. The aim of this study was to explore longitudinal associations of polypharmacy with loneliness and social isolation among older adults.MethodsParticipants aged 60 years and above in southern Sweden were invited for participation. A total of 1526 and 2556 participants were included in the separate analyses for loneliness and social isolation. Polypharmacy was defined as taking five or more medications. Associations of polypharmacy with occurrence of loneliness and social isolation were estimated using logistic regression models.ResultsDuring follow-up, 409 and 414 participants developed loneliness and social isolation, respectively. The odds for loneliness occurrence were higher for participants with polypharmacy compared to participants without polypharmacy (OR, 1.37; 95% CI, 1.05–1.78; P = 0.020). For participants without polypharmacy, the probability of developing loneliness was 0.28 (95% CI, 0.25–0.31), while for those with polypharmacy this probability was 25% higher (0.35; 95% CI, 0.30–0.39). The odds for social isolation occurrence were higher for participants with polypharmacy compared to participants without polypharmacy (OR, 1.29; 95% CI, 1.02–1.64; P = 0.036). For participants without polypharmacy, the probability of developing social isolation was 0.16 (95% CI, 0.14–0.18), while for those with polypharmacy this probability was 18% higher (0.19; 95% CI, 0.17–0.22).ConclusionsPolypharmacy was associated with loneliness and social isolation occurrence among older adults. Consideration of loneliness and social isolation are warranted when caring for older adults taking multiple medications

Effects of ultra-high field MRI environment on cognitive performance in healthy participants

Introduction: Ultra-high field MRI (UHF MRI) is rapidly becoming an essential part of our toolbox within health care and research studies; therefore, we need to get a deeper understanding of the physiological effects of ultra-high field. This study aims to investigate the cognitive performance of healthy participants in a 7 T (T) MRI environment in connection with subjectively experienced effects. Methods: We measured cognitive performance before and after a 1-h 7T MRI scanning session using a Digit Symbol Substitution Test (DSST) in 42 subjects. Furthermore, a computer-based survey regarding the subjectively experienced effects in connection with the MRI examination was distributed. Similarly, two DSSTs were also performed by a control group of 40 participants. Results: Even though dizziness was the strongest sensory perception in connection to the MRI scanning, we did not find any correlation between dizziness and cognitive performance. Whilst the control group improved (p=<0.001) on their second DSST the MRI group showed no significant difference (p=0.741) in the DSST before and after MRI scanning. Conclusion: Transient effect on cognition after undergoing MRI scanning can't be ruled out as the expected learning effect on the DSST was not observed. Implications for practice: Increasing understanding of the possible adverse effects may guide operators in performing UHF MRI in a safe way and with person-centered care. Furthermore, it can guide researchers in setting up research protocols to minimize confounding factors in their fMRI studies due to the transient adverse effects of the UHF environment

Combustion of micron-sized Al-Mg alloy wires in hot H2O/O2/N2 flows

The use of aluminum-magnesium (Al-Mg) alloy particle as energetic additive in solid propellants was previously shown to have many advantages over pure Al particle, such as relatively low ignition temperature, high reaction rate and low particle agglomeration rate. In this paper, the combustion of Al-Mg alloy in hot H2O/O2/N2 flows was experimentally studied using wires with a diameter of 200 µm. The employment of wires instead of particles provided a unique opportunity to obtain fundamental insights into the combustion process due to the spatial stabilization and large size of the sample. High-speed imaging showed that the combustion of Al-Mg alloy wire could be divided into three stages, namely pre-heating, ignition, and combustion. Spectral measurements suggested that the chemiluminescence emissions from Mg, MgO and MgOH dominated the collected spectra, in spite of only 3% Mg (by weight) existed in the alloy. Additionally, it was observed that moderate gaseous reactions could occur well before the breakup of the passive oxide coating, generating obvious fine oxide smokes. Moreover, consumption rates of the wire in different hot oxidizers were obtained and compared. It was shown that O2 featured more significant promotion of the reaction than H2O. Nevertheless, without O2, much less metal-oxide particles were generated. Temperature measurements indicated that the ignition temperature lied within 2160 ∼ 2220 K, which was lower than the melting points of Al2O3 (2350 K) and MgO (3125 K). Large single burning Al-Mg alloy droplets (∼200 µm diameter) were generated after the micro-explosion inside the wire. It was found that the combustion of Al-Mg alloy in both H2O/O2/N2 and H2O/N2 atmospheres were diffusion-controlled with a stand-off distance around 150 µm (stand-off ratios at ∼ 1.3). Finally, SEM and EDS measurements revealed that Al, Mg and O elements coexisted on the surface of the burnt wires. Nevertheless, it was observed that the oxidization of Mg started before Al, and the reaction of alloy was more intense when O2 existed. This led to the generation of much thicker oxide layers and larger number of nanoparticles

Imagining circular carbon : A mitigation (deterrence) strategy for the petrochemical industry

Petrochemical producers both rely upon and generate some of the most problematic substances in the current age of socioecological crisis: fossil fuels and plastics. With mounting calls to cap fossil fuel extraction as well as plastics production, the industry appears to be caught between a rock and a hard place. Nonetheless, betting on continuously increasing global plastic demand, petrochemical production is expanding significantly. This predicament raises the question of how the industry attempts to square increasing petrochemical production with the need to address environmental issues. In recent years, leading actors in and around the industry have promoted notions of carbon circularity as a desirable mitigation strategy. In this paper, we examine this strategy, using discourse analysis to uncover what we refer to as the imaginary of circular carbon. We highlight how the circular carbon imaginary risks delaying climate mitigation by rendering alternative mitigation pathways undesirable. It does so by reconciling increased production, carbon neutrality, and circular economy in a vision of a circular carbon economy, framing the climate crisis as an issue of carbon management. In the circular carbon economy, carbon dioxide, petrochemicals, and plastics all fit as mere flows of carbon. The circular carbon imaginary thereby helps future-proof the petrochemical industry in legitimizing its carbon-intensive practises essential to the fossil world order and the plastic crisis

Ambient pressure operando catalytic characterization by combining PM-IRRAS with planar laser-induced fluorescence and surface optical reflectance imaging

We present a combination of optical operando techniques that allow us to bridge the pressure gap in heterogeneous catalysis. By combining Polarization Modulated - InfraRed Reflection Absorption Spectroscopy (PM-IRRAS) with two dimensional-Surface Optical Reflectance (2D-SOR) and Planar Laser Induced Fluorescence (PLIF), we can simultaneously measure the adsorbed species on the catalyst surface, monitor the surface oxide formation across the catalyst surface and image the gas phase right above the catalyst surface, respectively. In a single measurement, we are able to follow heterogeneous catalytic reactions temporally- and spatially resolved with all three optical techniques, which are additionally supported by Mass Spectrometry (MS). To validate the experimental setup, we perform two experiments studying CO oxidation on Pd(100) at 150 mbar and 910 mbar by ramping the sample temperature. PM-IRRAS and 2D-SOR reveal that the formation of well-defined ultrathin surface oxide coincides with the disappearance of CO adsorption on the surface. At the same time, PLIF and MS confirm the simultaneous transition into a mass-transfer-limited (MTL) regime. A difference between 150 and 910 mbar can be seen in the light-off temperature caused by different partial pressures of CO and in the spatial distribution of the gas cloud across the surface in space caused by gas diffusion. This emphasizes the need for spatially-resolved gas phase diagnostics in heterogeneous catalysis. The combination of all techniques aids our understanding of the gas-surface interaction