Microwave preparation of polyoxoniobates and -tantalates afford a more rapid alternative to conventional hydrothermal methods of synthesis, in addition to allowing for the use of anhydrous niobium pentoxide in lieu of niobic acid, albeit with diminished yields. Limitations associated with the pH at which different oxides can be activated and how this affects the accessibility of different products

Based on extensive experimental investigations on many different oxide nanoparticles, it is now a well-established view that the counter-ions exhibit ion specific effects due to their high charge density and strong interaction with oppositively charged surfaces. On the other hand, studies regarding co-ion effects are scarcely reported in the literature. In this study we have measured the surface c

This paper presents a systematic investigation of the influence of streamturbulence on the pressure forces on a single tube. Grids were used to producedifferent turbulent flow fields with longitudinal integral scale (eddy size)ranging from 0.1 to 0.5 tube diameters and turbulence intensities ranging from0.1 to 3-2 %. The measurements were carried out at two Reynolds numbers, 2.7 - 10 and U.1-104 ,

Calculations of two-dimensional unsteady flow around a quadratic two-dimensional cylinder at zero angle of attack are performed. The Reynolds numbers are low (Re = 45 - 250) so that the flow presumably is laminar. At Re > 50 a von Karman vortex street with a well-defined shedding frequency is predicted. An incompressible SIMPLEC finite volume code employing non-staggered grid arrangement is used.

Introduction Trauma accounts for nearly 10% of the global burden of disease. Several trauma life support programmes aim to improve trauma outcomes. There is no evidence from controlled trials to show the effect of these programmes on patient outcomes. We describe the protocol of a pilot study that aims to assess the feasibility of conducting a cluster randomised controlled trial comparing advanced

Large Eddy Simulations (LESs) of flow around a square cylinder at Re = 22 × 103 are performed employing a dynamic one-equation subgrid model. An implicit fractional step method finite-volume code with second-order accuracy in space and time is used. By using a periodic boundary condition, the spanwise dimension is four times the side length of the cylinder. Some global quantities, such as the domi

2D and 3D unsteady flow past a rigid prism of a squarecross-section with one side facing the oncoming flow is numerically simulated for Reynolds numbers between 200 to 500. An incompressible code is used employing an implicit fractional step method finite-volume with second-order accuracy in space and time. For 2D flow, it is found that, for Re >300, the time-mean flow patterns are not perfectly s

Ruddlesden-Popper perovskites (RPPs) have been demonstrated as a very promising approach for tuning the emission color of perovskite light-emitting diodes (PeLEDs). However, achieving high-performance red PeLEDs with recommendation 2020 color coordinates is still challenging due to the lack of reasonable control over the properties of RPP films. Here, we demonstrate that the judicious selection of

Defect management strategies are vital for enhancing the performance of perovskite-based optoelectronic devices, such as perovskite-based light-emitting diodes (PeLEDs). As additives can fucntion both as acrystallization modifier and/or defect passivator, a thorough study on the roles of additives is essential, especially for blue emissive Pe-LEDs, where the emission is strictly controlled by the

Harvesting the excess energy from absorbed above bandgap photons is a promising approach to overcome the detailed balance limit for higher solar cell efficiencies. However, this remains very challenging for 2D layered halide perovskites as the fast excess energy loss competes effectively with charge extraction. Herein, the authors engineer the energy cascade manifold of quantum well (QW) states in

Perovskite light-emitting diodes (PeLEDs) have recently shown significant progress with external quantum efficiencies (EQEs) exceeding 20%. However, PeLEDs with pure-red (620−660 nm) light emission, an essential part for full-color displays, remain a great challenge. Herein, a general approach of spacer cation alloying is employed in Ruddlesden–Popper perovskites (RPPs) for efficient red PeLEDs wi

Excitonic effects underpin the fascinating optoelectronic properties of 2D perovskites that are highly favorable for photovoltaics and light-emitting devices. Analogous to switching in transistors, manipulating these excitonic properties in 2D perovskites using coherent phonons could unlock new applications. Presently, a detailed understanding of this underlying mechanism remains modest. Herein, t

Two-dimensional (2D) lead halide Ruddlesden-Popper perovskites (RPP) have recently emerged as a prospective material system for optoelectronic applications. Their self-assembled multi quantum-well structure gives rise to the novel interwell energy funnelling phenomenon, which is of broad interests for photovoltaics, light-emission applications, and emerging technologies (e.g., spintronics). Herein

The outstanding optoelectronic performance of lead halide perovskites lies in their exceptional carrier diffusion properties. As the perovskite material dimensionality is reduced to exploit the quantum confinement effects, the disruption to the perovskite lattice, often with insulating organic ligands, raises new questions on the charge diffusion properties. Herein, we report direct imaging of >1

Amongst the many spectacular properties of hybrid lead halide perovskites, their defect tolerance is regarded as the key enabler for a spectrum of high-performance optoelectronic devices that propel perovskites to prominence. However, the plateauing efficiency enhancement of perovskite devices calls into question the extent of this defect tolerance in perovskite systems; an opportunity for perovsk