MRC Laboratory of Molecular Biology
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Immersive 3D sketching tools: Implications for visual thinking and communication
No full textPaper-based (PB) sketching involves the challenge of representing three-dimensional (3D) shapes on two-dimensional (2D) surfaces. The recent generation of virtual reality (VR) sketching tools offer a way to overcome this challenge. These immersive 3D sketching environments permit the rapid construction of freehand stroke-based 3D models in 3D space while replicating the immediate experience of PB sketching. To explore the potential advantages of VR sketching in visual thinking and visual communication, we conducted investigations with sixteen architectural students engaged in PB and VR sketching tasks. We observed their visualization behavior during VR sketching and their behavior in transitioning between PB and VR sketching. The participants experiences of the two media were also recorded in semi-structured interviews and questionnaires. Our observations show that immersive 3D sketching is a unique form of visual representation that facilitates the rapid and flexible creation of large and detailed (but inaccurate) 3D computer models. It is a multimodal medium that supports visual thinking and communication behaviors associated with PB sketching, CAD modeling, physical model-making and gesturing, all within the same space. This unique combination enables users to engage in visual thinking and visual communication activities in ways that cannot presently be achieved with any other single representation technique
Design for Accelerated Testing of DC-Link Capacitors in Photovoltaic Inverters Based on Mission Profiles
No full textThe dc-link capacitor is considered as a weak component in photovoltaic (PV) inverter systems and its reliability needs to be evaluated and tested during the product development. Conventional reliability testing methods for capacitors are typically carried out under constant loading conditions, which do not reflect the real operating conditions (e.g., mission profile) of the dc-link capacitor in PV inverters. To address this issue, a new reliability testing concept for the dc-link capacitor in PV inverters is proposed in this article. In contrast to the conventional method, the proposed reliability testing method designs the test profile through the modification of the original mission profile (e.g., solar irradiance and ambient temperature) in order to maintain the test condition as close to the real application as possible. A certain acceleration factor is applied during the mission profile modification based on the lifetime model of the capacitor, in order to increase the thermal stress of the dc-link capacitor during test, and thereby effectively reduce the testing time
Direct-writing microporous polymer architectures-print, capture and release
No full textIn the nature-inspired breath figure method, rafts of condensed water droplets self-organise and imprint into a permanent microporous polymer structure. This could have exciting applications in drug delivery, tissue engineering and sensors but it is extremely difficult to control or functionalise the final structure. Here, we show direct-writing of droplets onto fluid surfaces by inkjet printing as a breakthrough to dial-in a required pattern, structure and function into the polymer film
Generating an aerosol of homogeneous, non-spherical particles and measuring their bipolar charge distribution
No full textThe Aerodynamic Aerosol Classifier (AAC) and Differential Mobility Analyzer (DMA) are aerosol classifiers commonly used to generate a monodispersed aerosol by selecting particles within a narrow range of relaxation times or electrical mobilities, respectively. However, generating an aerosol of homogeneous particles, which has narrow ranges of particle mass, mobility and relaxation time simultaneously, with either of these methods is challenging. Particles classified by the DMA are often not homogeneous (or monodispersed) due to multiply-charged particles. While the AAC overcomes this challenge for spherical particles, homogeneity is not achieved with non-spherical particles due to their effective density varying with particle size. This study demonstrates using an AAC and DMA in tandem to generate an aerosol of homogeneous, non-spherical particles. This approach is validated using scanning electron microscope (SEM) images and electrical mobility measurements of the tandem-classified particles to highlight their homogeneity. To limit the effects of multiple charging during DMA classification, only a subset of DMA and AAC setpoints are permitted. While this subset is not representative of “average” non-spherical particles from the same aerosol source, this subset of low-density particles deviates the most from spherical morphology, and thus, provides insights into the upper bound of other particle properties, such as charging. Using this approach to select homogeneous particles, the bipolar charge distribution of low-density soot aggregates is then measured using another DMA. This AAC-DMA-DMA approach is demonstrated to measure up to 17 individual charge states (i.e. −8 to +8) after neutralization (with 85Kr) of size-resolved, soot aggregates with mobility diameters between 80 and 433 nm. The low-density soot aggregates obtain higher charges than predicted by theory, which overestimates the uncharged fraction (by 0.042–0.069) and, to a lesser extent, the single charge fractions (by up to 0.037) of the low-density soot aggregates, while underestimating their proportion of multiple charging (by up to 0.135 cumulatively at one particle size or up to 0.039 at one multiple charge state and size). These charging discrepancies represent an upper bound of the bipolar charging of average aggregates from the same source of flame soot
An Abdominal Phantom with Tunable Stiffness Nodules and Force Sensing Capability for Palpation Training
No full textRobotic phantoms enable advanced physical examination training before using human patients. In this article, we present an abdominal phantom for palpation training with controllable stiffness liver nodules that can also sense palpation forces. The coupled sensing and actuation approach is achieved by pneumatic control of positive-granular jammed nodules for tunable stiffness. Soft sensing is done using the variation of internal pressure of the nodules under external forces. This article makes original contributions to extend the linear region of the neo-Hookean characteristic of the mechanical behavior of the nodules by 140% compared to no-jamming conditions and to propose a method using the organ level controllable nodules as sensors to estimate palpation position and force with a root-mean-square error of 4% and 6.5%, respectively. Compared to conventional soft sensors, the method allows the phantom to sense with no interference to the simulated physiological conditions when providing quantified feedback to trainees, and to enable training following current bare-hand examination protocols without the need to wear data gloves to collect data
A fork in the road: Which energy pathway offers the greatest energy efficiency and CO<inf>2</inf> reduction potential for low-carbon vehicles?
No full textA future energy system for road transport requires optimised energy use and primary energy decarbonisation to achieve global CO2 reduction goals. Simultaneously decarbonising transport with other sectors of the economy places additional demands on limited low-carbon energy sources, requiring efficient processes within a fuel pathway from energy source to -energy use. Battery electric vehicles (BEVs) and fuel-cell electric vehicles (FCEVs) are low-carbon options that reduce tailpipe emissions, but differ in overall efficiency, associated carbon intensity, and cost. Current commercialised technologies, as well as theoretical maximums, are aggregated in a stochastic analysis to quantify the energy efficiency and CO2 differences for BEV and FCEV energy systems. Carbon capture and storage improves source-to-wheels CO2 intensity for hydrogen produced from steam methane reformation (27 gCO2/km with carbon capture and store and 140 gCO2/km without for light-duty FCEVs). Light-duty BEVs have a lower CO2 intensity (11 gCO2/km) using decarbonised grid electricity and are 65% more efficient than light-duty FCEVs using grid energy. These effects translate to heavy-good vehicles but with added complexity. In a maximised trailer volume scenario, electric and fuel-cell heavy-good vehicles have similar projected carbon intensities from a natural gas primary energy source, but electric heavy-good vehicle using conventional battery systems or an electric road system are able to achieve a 55% and 67% carbon reduction (gCO2/m3 km) compared to fuel-cell heavy-goods vehicles, respectively
Ultrasound-guided targeted biopsies of CT-based radiomic tumour habitats: technical development and initial experience in metastatic ovarian cancer
No full textPurpose: To develop a precision tissue sampling technique that uses computed tomography (CT)–based radiomic tumour habitats for ultrasound (US)-guided targeted biopsies that can be integrated in the clinical workflow of patients with high-grade serous ovarian cancer (HGSOC). Methods: Six patients with suspected HGSOC scheduled for US-guided biopsy before starting neoadjuvant chemotherapy were included in this prospective study from September 2019 to February 2020. The tumour segmentation was performed manually on the pre-biopsy contrast-enhanced CT scan. Spatial radiomic maps were used to identify tumour areas with similar or distinct radiomic patterns, and tumour habitats were identified using the Gaussian mixture modelling. CT images with superimposed habitat maps were co-registered with US images by means of a landmark-based rigid registration method for US-guided targeted biopsies. The dice similarity coefficient (DSC) was used to assess the tumour-specific CT/US fusion accuracy. Results: We successfully co-registered CT-based radiomic tumour habitats with US images in all patients. The median time between CT scan and biopsy was 21 days (range 7–30 days). The median DSC for tumour-specific CT/US fusion accuracy was 0.53 (range 0.79 to 0.37). The CT/US fusion accuracy was high for the larger pelvic tumours (DSC: 0.76–0.79) while it was lower for the smaller omental metastases (DSC: 0.37–0.53). Conclusion: We developed a precision tissue sampling technique that uses radiomic habitats to guide in vivo biopsies using CT/US fusion and that can be seamlessly integrated in the clinical routine for patients with HGSOC. Key Points: • We developed a prevision tissue sampling technique that co-registers CT-based radiomics–based tumour habitats with US images. • The CT/US fusion accuracy was high for the larger pelvic tumours (DSC: 0.76–0.79) while it was lower for the smaller omental metastases (DSC: 0.37–0.53)
Precise protein conjugation technology for the construction of homogenous glycovaccines
No full textThe introduction of vaccines for the treatment and prevention of bacterial or viral diseases in the early 19th century marked a crucial turning point in medical history. Since then, extensive immunization campaigns have eradicated smallpox and drastically reduced the number of diphtheria, tetanus, pertussis and measles cases worldwide. Although a broad selection of vaccines is available, there remains a need to develop additional vaccine candidates against a range of dangerous infectious diseases, preferably based on precise syntheses that lead to homogenous formulations. Different strategies for the construction of this type of vaccine candidates are being pursued. Glycoconjugate vaccines are successful in the fight against bacterial and viral infectious diseases. However, their exact mechanism of action remains largely unknown and the large-scale production of chemically defined constructs is challenging. In particular, the conjugation of the carbohydrate antigen to the protein carrier has proved to be crucial for the properties of these vaccines. This review highlights some of the latest findings and developments in the construction of glycoconjugate vaccines by means of site-specific chemical reactions
Improved Method for the Seismic Design of Anchored Steel Sheet Pile Walls
No full textThis paper describes a new pseudostatic approach for an efficient seismic design of anchored steel sheet pile (ASSP) walls supported by shallow passive anchorages. As for other retaining structures, energy dissipation during strong earthquakes leading to reduced inertia forces can be achieved by allowing the activation of ductile plastic mechanisms. To this end, a robust method is required to identify all the possible yielding mechanisms and to guarantee the desired strength hierarchy. It is shown that dissipative mechanisms for ASSP walls correspond either to the local attainment of the soil shear strength in the supporting soil and around the anchor, or in the activation of a log-spiral global failure surface. A new limit equilibrium method is proposed to compute the critical acceleration of the system, corresponding to the actual mobilization of its strength, and the maximum internal forces in the structural members. Theoretical findings are validated against both existing dynamic centrifuge data and the results of original pseudostatic and fully dynamic numerical analyses
Reliable 4.8 T trapped magnetic fields in Gd-Ba-Cu-O bulk superconductors using pulsed field magnetization
No full textA robust and reliable in-situ magnetization method is essential for exploiting the outstanding magnetic flux trapping ability of bulk superconductors in practical applications. We report a 4.8 T peak trapped magnetic field, B T, achieved at 30 K in a 36 mm diameter GdBa2Cu3O7-δ -Ag bulk superconductor using pulsed field magnetization (PFM). To realize this, we have developed a reliable two-step multi-pulse PFM process based on understanding and exploiting the avalanche-like flux jump phenomenon observed in these materials. The magnitude of the applied pulsed magnetic field (B a) necessary to trap 4.8 T was merely 5.29 T, corresponding to a remarkable magnetization efficiency (B T/B a) of 90%