We identify usability challenges facing consumers adopting Virtual Reality (VR) head-mounted displays (HMDs) in a survey of 108 VR HMD users. Users reported significant issues in interacting with, and being aware of their real-world context when using a HMD. Building upon existing work on blending real and virtual environments, we performed three design studies to address these usability concerns. In a typing study, we show that augmenting VR with a view of reality significantly corrected the performance impairment of typing in VR. We then investigated how much reality should be incorporated and when, so as to preserve users' sense of presence in VR. For interaction with objects and peripherals, we found that selectively presenting reality as users engaged with it was optimal in terms of performance and users' sense of presence. Finally, we investigated how this selective, engagement-dependent approach could be applied in social environments, to support the user's awareness of the proximity and presence of others.

While it has been demonstrated that large scale liquid exfoliation of graphene is possible using high-shear exfoliation, it has not yet been shown to be applicable to a broader range of layered materials. In addition, it would be useful to determine whether the mechanisms reported for shear exfoliation of graphene also apply to other 2D materials. In this work we show that previous models describing high-shear exfoliation of graphene apply to MoS2 and WS2. However, we find the minimum shear rate required to exfoliate MoS2 and WS2 to be ~310 4 s-1 , somewhat higher than the value for graphene. We also demonstrate the scalability of shear exfoliation of WS2. By measuring and then optimising the scaling parameters, shear exfoliation of WS2 is shown to be capable of reaching concentrations of 1.82 g/L in 6 hours and demonstrating a maximum production rate of 0.95 g/hour.

We describe an approach to improving the design and development of Brain-Computer Interface (BCI) applications by simulating the error-prone characteristics and subjective feel of electroencephalogram (EEG), motor-imagery based BCIs. BCIs have the potential to enhance the quality of life of people who are severely disabled, but it is often timeconsuming to test and develop the systems. Simulation of BCI characteristics allows developers to rapidly test design options, and gain both subjective and quantitative insight into expected behaviour without using an EEG cap. A further motivation for the use of simulation is that 'impairing' a person without motor disabilities in a game with a disabled BCI user can create a level playing field and help carers empathise with BCI users. We demonstrate a use of the simulator in controlling a game of Brain Pong.

Virtual reality users are torn between the real and virtual worlds. Determining how, and when, to show elements of reality in a virtual view is key to providing usable VR experiences.

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