Electroporation, the transient increase in the permeability of cell membranes when exposed to a high electric field, is an established in vitro technique and is used to introduce DNA or other molecules into cells. When the trans-membrane voltage induced by an external electric field exceeds a certain threshold (normally 0.2-1 V), a rearrangement of the molecular structure of the membrane occurs, leading to pore formation in the membrane and a considerable increase in the cell membrane permeability to ions, molecules and even macromolecules. This phenomenon is, potentially, the basis for many in vivo applications such as electrochemotherapy and gene therapy, but still lacks a comprehensive theoretical basis. This article reviews the state of current electroporation theories and briefly considers current and potential applications in biology and medicine.

Micron sized, lipid stabilized bubbles of gas are of interest as contrast agents for ultra-sound (US) imaging and increasingly as delivery vehicles for targeted, triggered, therapeutic delivery. Microfluidics provides a reproducible means for microbubble production and surface functionalisation. In this study, microbubbles are generated on chip using flow-focussing microfluidic devices that combine streams of gas and liquid through a nozzle a few microns wide and then subjecting the two phases to a downstream pressure drop. While microfluidics has successfully demonstrated the generation of monodisperse bubble populations, these approaches inherently produce low bubble counts. We introduce a new micro-spray flow regime that generates consistently high bubble concentrations that are more clinically relevant compared to traditional monodisperse bubble populations. Final bubble concentrations produced by the micro-spray regime were up to 10(10) bubbles mL(-1). The technique is shown to be highly reproducible and by using multiplexed chip arrays, the time taken to produce one millilitre of sample containing 10(10) bubbles mL(-1) was ∼10 min. Further, we also demonstrate that it is possible to attach liposomes, loaded with quantum dots (QDs) or fluorescein, in a single step during MBs formation.

A number of general conclusions are evident: (1) small field OR(det) are very sensitive to the simulated source parameters, and therefore, rigorous Monte Carlo linac model commissioning, with respect to measurement, must be pursued prior to use, (2) backscattered dose to the monitor chamber should be included in simulated OR(det) calculations, (3) the corrections required for diode detectors are design dependent and therefore detailed detector modeling is required, and (4) the reported detector specific correction factors may be applied to experimental small field OR(det) consistent with those presented here.

The studies used different methodologies with no standardized measurement techniques. Measurements were taken by observers from different medical disciplines of varying grade and levels of training. Standard training and formal quality assurance of ultrasound measurements are important components of an effective AAA screening programme.

7This paper reviews the published data on the performance and use of domestic refrigerators 8 throughout the world in the last 30 years. While there is considerable legislation defining 9 maximum temperatures during the production, distribution and retailing of chilled food, as 10 soon as the consumer purchases the food, it is outside of any of these legislative 11 requirements. Inadequate domestic refrigeration or cooling is frequently cited as a possible 12 factor in food poisoning incidents. It is clear from the many published surveys that many 13 refrigerators throughout the world are running at higher than recommended temperatures. 14 Since even these recommended temperatures are higher than the 0 to 1°C that is usually the 15 recommended temperature range for storing fish and seafood, meat and many chilled 16 products the current situation is even more detrimental to maintaining the high quality life of 17 chilled foods. Despite numerous surveys around the world, how refrigerator temperatures 18 and cleanliness impacts on consumer health remains to be fully assessed. 19

Measurements of the attenuation and velocity of ultrasound from 0.3 to 0.8 MHz have been performed on a number of bovine cancellous bone samples. The influence of bone mineral content has been isolated by measuring the acoustic properties of the samples at various stages of demineralization resulting from controlled nitric acid attack. The correlation coefficient r, between the attenuation at different frequencies and bone density was found to be in the range 0.68-0.97. Broadband ultrasonic attenuation (BUA) was also calculated and produced r values between 0.84 and 0.99. The velocity measurements indicated a correlation greater than 0.97 in all cases. Thus velocity is the parameter most sensitive to changes in bone mineral density alone. Attenuation and BUA are less well correlated presumably because of a sensitivity to minor structural change.

Octopamine synthesized in vitro from tyramine by Limulus lateral and ventral eyes was located by light microscopic and electron microscopic autoradiography in efferent fibers which innervate ventral photoreceptors and lateral eye ommatidia. Newly synthesized octopamine was released from efferent fibers in response to depolarization in high concentrations of potassium. We propose that octopamine is a neurotransmitter of efferent fibers that may modulate basic retinal processes such as photoreceptor sensitivity, photomechanical movements, and photoreceptive membrane turnover.

The measurement of attenuation and velocity of ultrasound in cancellous bovine femora has been studied. The dependence of both attenuation between 0.2 and 0.8 MHZ and velocity on the bone density has been measured. The results show a correlation coefficient of around 0.5 for attenuation and density, and a value of roughly 0.85 for velocity and density. The clinical consequences for the use of low frequency ultrasound as a diagnostic tool in bone disease are discussed.