Atomic resolution three-dimensional electron diffraction microscopy

We report the development of a novel form of diffraction-based 3D microscopy to overcome resolution barriers inherent in high-resolution electron microscopy and tomography. By combining coherent electron diffraction with the oversampling phasing method, we show that the 3D structure of a nanocrystal can be determined ab initio at a resolution of 1 A from 29 simulated noisy diffraction patterns. This new form of microscopy can be used to image the 3D structures of nanocrystals and noncrystalline samples, with resolution limited only by the quality of sample diffraction.     

Magnetic resonance imaging in a model of atherosclerosis: use of a collar around the rabbit carotid artery

Transverse cardiac-cycle gated high resolution magnetic resonance images have been obtained from the neck of the New Zealand white rabbit both in normal animals and from those in which a collar had been earlier positioned around one carotid artery. The study included animals fed on normal and on high cholesterol diets with the surgical modification having been demonstrated previously to cause a rapid and reproducible lesion resembling early atherosclerosis. The aim of the work was to investigate the attainable spatial resolution and sensitivity at a field strength of 2 T using a large radiofrequency transmitter system and a surface coil receiver with which spin-echo images have been obtained. Visualization was enhanced using a three-dimensional interpolation technique. An image resolution of 200 microns was readily obtained but was shown to be insufficient for delineating pathological features within the artery wall such as intimal layer thickening. The results have been compared with histopathological findings which confirmed that any morphological changes were within the pixel resolution of the image. Extensions to the methodology are proposed which should be able to detect atherosclerotic changes with a resolution of 50 microns within a feasible imaging time. In addition, the MRI study of how the surgical intervention alters the artery shape and curvature was carried out and the MRI demonstrated that collar implantation in general does not occlude the artery and causes only a slight and gradual degree of curvature to the vessel.     

The systematics of nuclear single-particle states (II). the region A < 35

The energies of single-particle states in nuclei with A < 35 are obtained as eigenvalues of a local Saxon-Woods potential with depth depending linearly on A and on the nuclear symmetry parameter.     

Acoustic radiation from the elastic impact of a sphere with a slab

The transient sound radiation from the impact of a spherical object with a slab is analysed theoretically and compared with experimental results. It is shown that the major source of sound radiation when a sphere impinges on a massive plate is due to the sudden change of velocity of the sphere. By using the method of images, an analytical expression predicting the sound pressure waveform is obtained. Experimental results confirm the theoretical analysis and provide further explanation of this rigid body type of acoustic radiation.     

In beam measurements of the F colouring curves for NaCl at and above room temperature

In beam measurements have been made of the F colouring curves in NaCl between 20 and 300°C. The first colouring stage has been empirically fitted by up to three exponential components which become smaller and faster with increasing temperature. A model is presented which gives physical significance to the fitting parameters.     

Substituted aziridines by lithiation-electrophile trapping of terminal aziridines

[reaction: see text] Regio- and stereoselective deprotonation of N-Bus (Bus = tert-butylsulfonyl)-protected terminal aziridines with lithium 2,2,6,6-tetramethylpiperidide generates a nonstabilized (H-substituted) aziridinyl anion that undergoes in situ or external electrophile trapping under experimentally straightforward conditions to give trans-disubstituted aziridines in good to excellent yields.     

The use of acoustoelectrochemistry to investigate rectified diffusion

This paper describes the approach to bubble related phenomena using a novel 'acoustoelectrochemical' technique designed to investigate the physical and chemical effects of the acoustically induced motion of the bubble wall. In particular it describes the behaviour of a suspended gas bubble irradiated with sound of an appropriate frequency and pressure to induce bubble wall oscillation. The first electrochemical measurement of the growth of a bubble through rectified diffusion is demonstrated. The technique employed relies on the sensitivity of a scanning electrochemical microscope (SECM) deployed close to the gas/liquid interface of a bubble. The growth rate of the bubble (<0.1 microms(-1)) is reported. It will be also demonstrated that gas exchange across the phase boundary at the bubble wall, can be successfully probed when the bubble is stationary.