MRC Laboratory of Molecular Biology
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Fabrication of TiO<inf>2</inf>microspikes for highly efficient intracellular delivery by pulse laser-assisted photoporation
No full textThe introduction of foreign cargo into living cells with high delivery efficiency and cell viability is a challenge in cell biology and biomedical research. Here, we demonstrate a nanosecond pulse laser-activated photoporation for highly efficient intracellular delivery using titanium dioxide (TiO2) microspikes as a substratum. The TiO2microspikes were formed on titanium (Ti) substrate using an electrochemical anodization process. Cells were cultured on top of the TiO2microspikes as a monolayer, and the biomolecule was added. Due to pulse laser exposure of the TiO2microspike-cell membrane interface, the microspikes heat up and induce cavitation bubbles, which rapidly grow, coalesce and collapse to induce explosion, resulting in very strong fluid flow at the cell membrane surface. Thus, the cell plasma membrane disrupts and creates transient nanopores, allowing delivery of biomolecules into cells by a simple diffusion process. By this technique, we successfully delivered propidium iodide (PI) dye in HeLa cells with high delivery efficiency (93%) and high cell viability (98%) using 7 mJ pulse energy at 650 nm wavelength. Thus, our TiO2microspike-based platform is compact, easy to use, and potentially applicable for therapeutic and diagnostic purposes
Data-efficient neural network for track profile modelling in cold spray additive manufacturing
No full textCold spray is emerging as an additive manufacturing technique, particularly advantageous when high production rate and large build sizes are in demand. To further accelerate technology’s industrial maturity, the problem of geometric control must be improved, and a neural network model has emerged to predict additively manufactured geometry. However, limited data on the effect of deposition conditions on geometry growth is often problematic. Therefore, this study presents data-efficient neural network modelling of a single-track profile in cold spray additive manufacturing. Two modelling techniques harnessing prior knowledge or existing model were proposed, and both were found to be effective in achieving the data-efficient development of a neural network model. We also showed that the proposed data-efficient neural network model provided better predictive performance than the previously proposed Gaussian function model and purely data-driven neural network. The results indicate that a neural network model can outperform a widely used mathematical model with data-efficient modelling techniques and be better suited to improving geometric control in cold spray additive manufacturing
Electronic, structural and optical properties of cerium and zinc co-doped organic-inorganic halide perovskites for photovoltaic application
No full textOrganic-inorganic hybrid perovskites have been receiving considerable attention due to their excellent performances. However, the pollution of the lead element and the instability under strong light and high temperatures are still problems to be solved. In this work, we studied the structure and photoelectrical properties of Cs and Zn co-doped organic-inorganic hybrid perovskite by first-principles calculations. Results showed the synergy effects of A-site and B-site doping improved the lattice stability, reduced pollution via the decreased contents of lead elements and also induced an adjustable bandgap of 1.5–2.2 eV. The optical absorption of perovskites with different doping ratios was enhanced in the visible region. The hybridization among Zn 3d4s, Pb 6s6p, and I 5s5p states were observed, clarifying the origin of the enhancement. The Cs and Zn co-doped perovskites with adjustable band gaps are expected to be used in single-junction, multijunction, and tandem solar cells
True Origin of Gate Ringing in Superjunction MOSFETs: Device View
No full textAs superjunction devices are scaled down to smaller dimensions, the gate ringing becomes more prominent in dynamic switching. The exact origin of superjunction MOSFET's gate ringing has not been so far identified as the conventional three-terminal measurement method cannot capture the dynamic behavior of the device, in particular the redistribution of charge between the different internal capacitive components in the superjunction structure. In this article, it is found that the gate ringing is highly related to the input capacitance. Specifically, by employing a TCAD model with a split gate method, the gate-to-source (CGS) and gate-to-drain (CGD) current are investigated during the dynamic transitions. The gate ringing is highly dependent on sum of the input capacitances (CGS + CGD) for the turn-on. In the case of the turn-off, however, the gate ringing is affected by the ratio of the input capacitances (CGD/CGS) and a lower CGS is desirable for a low gate oscillation
Thermal management challenges for HEA – FUTPRINT 50
No full textElectric and Hybrid-Electric Aircraft (HEA) incorporate new systems, which demand an integration level higher than classical propulsion architectures systems do. High power electrical motors, converters, batteries or fuel cells, and distributed propulsion, all introduce new kinds of heat sources and dynamics that have to be accounted for and regulated. The latent opportunity to explore synergies among these systems requires the development of new models and their coupling with multi-disciplinary design optimization (MDO) toolchains. Also, an understanding of the implications into aircraft operations and trade-offs are critical to evaluate and validate gains at the aircraft level. This paper provides a definition of thermal management and functions of thermal management system (TMS) in aircraft, HEA thermal management challenges, main opportunities, conclusions and the way forward. A discussion of road ahead, regarding development of capabilities to support the design of TMS will be brought to the fore along the project, showcasing the open approach of FUTPRINT50 to be driven by open collaboration in order to accelerate the entry into service of this type of aircraft
Energy conscious management for smart metro traction power supply system with 4G communication loop
No full textThis paper proposes an intelligent traction power supply system for urban rail transits, employing the wireless 4G modules to establish a communication loop among the trains, the ground bidirectional converters and the top-level energy management system. On this basis, an energy-conscious management system is developed, which obtains the instantaneous power and position of each train, parameters of the traction power supply system, real-time status of the substations and bidirectional converters through the 4G based communication loop to realize the digital reconstruction of the real traction power system for facilitating the ensuing optimizations. As physical executors, the bidirectional converters acquire their optimal DC output voltages from the genetic algorithm and then coordinately achieve the power flow dispatching of the entire metro line, so as to make the metro traction power system have a better power supply quantity and a higher efficiency. The full power scale (6.4 Mega-Watt) experiments conducted in actual Ningbo Metro Line 4 verify that the proposed EMS system is effective in energy-saving
Reliability-Based Lifetime Fatigue Damage Assessment of Offshore Composite Wind Turbine Blades
No full textThis paper presents a method for stochastic deterioration modeling and fatigue damage assessment for composite wind turbine blades operating in offshore environments. The fatigue damage of the composite blades is analyzed and assessed based on the estimates for the applied loads along the blade span, stress analysis, fatigue crack evolution, and lifetime probability of fatigue failure. The complex stress states of the blade are mainly caused by the aerodynamic loads generated by corrected blade element momentum theory, gravity loads, and centrifugal loads. The fatigue of the wind turbine blade is then investigated on the basis of the actual fatigue damage propagation process. The stochastic gamma process is introduced to calculate the probability of fatigue failure of the blade for various critical limits, and these results together with lifecycle cost analysis are employed to determine the optimum maintenance strategy. Finally, a numerical example for a National Renewable Energy Laboratory 5-MW wind turbine blade is adopted to demonstrate the applicability of the proposed method. The numerical results show that the proposed approach can provide a reliable tool for estimating stress states, evaluating fatigue damage, analyzing lifetime fatigue failure probability, and optimizing repair time of the composite wind turbine blade
The Development of a Generic Working Fluid Approach for the Determination of Transonic Turbine Loss
No full textDue to the vast number of potential working fluids incorporated within heat recovery cycles, there is a degree of uncertainty around the aerodynamic design and performance of the required turbomachinery. This paper aims to explore the aerodynamic performance of transonic turbines in a generic manner so that the accurate prediction of turbine performance can be made for a wide variety of working fluids. Within this study, a thermodynamic approach to model a generic working fluid is presented based on the Peng-Robinson equation of state. This model is used in combination with Computational Fluid Dynamics to complete a systematic study into how various fluid parameters impact turbine aerodynamic performance. Therefore, this work presents a step towards a turbine loss model which is applicable to any transonic vapour turbine
Understanding non-commuting travel demand of car commuters – Insights from ANPR trip chain data in Cambridge
No full textThe paper investigates the non-commuting travel demand of car commuters using Automatic Number Plate Recognition (ANPR) trip chain data in Cambridge, UK. A novel rule-based algorithm is developed for identifying commuting vehicles and the associated non-commuting trips. Identification results are validated with external data. Non-commuting travel demand is investigated in terms of trip probability, average trip frequency, duration and demand elasticity. The study finds that, first, non-commuting trips represent a significant source of travel demand for car commuters – car commuters who engage in non-commuting activities in their daily trip chains would on average spend approximately 2.7hr on those activities including travel time on a typical workday in Cambridge. Second, longer working hours are associated with a lower probability of engaging in non-commuting trips, implying a substitution effect within the daily travel time budget. Last, in terms of travel demand elasticity, non-commuting trips starting in the early morning (6–9am) are less elastic than those starting in the morning (9–12am) and during the lunch break (12-3pm). The varying demand elasticities are likely to be attributed to the different travel constraints associated with certain trip purposes. Implications for post-pandemic traffic demand and management are drawn
HoloBlade: an open-hardware spatial light modulator driver platform for holographic displays
No full textSpatial light modulators (SLMs) are key research tools in several contemporary applied optics research domains. In this paper, we present the argument that an open platform for interacting with SLMs would dramatically increase their accessibility to researchers. We introduce HoloBlade, an open-hardware implementation of an SLM driver-stack, and provide a detailed exposition of HoloBlade’s architecture, key components, and detailed design. An optical verification rig is constructed to demonstrate that HoloBlade can provide Fourier imaging capability in a 4f system. Finally, we discuss HoloBlade’s future development roadmap and the opportunities that it presents as a research tool for applied optics