Microbial Decontamination by Pulsed Electric Fields (PEF) in Winemaking

Pulsed Electric Fields (PEF) is a non-thermal technique that causes electroporation of cell membranes by applying very short pulses (μs) of a high-intensity electric field (kV/cm). Irreversible electroporation leads to the formation of permanent conductive channels in the cytoplasmic membrane of cells, resulting in the loss of cell viability. This effect is achieved with low energy requirements and minimal deterioration of quality. This chapter reviews the studies hitherto conducted to evaluate the potential of PEF as a technology for microbial decontamination in the winemaking process for reducing or replacing the use of SO2, for guaranteeing reproducible fermentations or for wine stabilization.

The Influence of Laser Drilling Process on the Microstructural Changes of Nickel Based Superalloy

Nimonic 263 is an alloy with superior mechanical strength and creep resistance at high temperatures and pressure, good formability, and corrosion and oxidation resistance. Due to their high beam density and very short pulses which reduces the heat affected zone (HAZ) Nd:YAG lasers are very suitable for materials drilling. In this paper, the Nimonic 263 sheets, thickness of 2 mm, are laser drilled with various parameters. The influence of laser drilling process on microstructural changes along with the geometrical characteristics are analysed and discussed.

Investigations of Fracture Zones in Crystalline Rock by Borehole Radar

A borehole pulse radar system has been developed as part of the International Stripa Project with the objective to identify and characterize fracture zones at a considerable distance from boreholes. The radar uses very short pulses, which are transmitted and received by dipole antennas inserted into the boreholes. The pulses are extremely broadband with center frequencies of 25–60 MHz corresponding to wavelengths of a few meters in the rock. At 25 MHz the attenuation in the Stripa granite is 28 dB/100 m and the pulse velocity is approximately 128 000 km/s. Reflection measurements have been used to identify fracture zones and determine their position and orientation. The zones often cause strong and well-defined reflections. Improvements in the pulse form and numerical filtering of the data have consequently made the radar a very efficient instrument for locating fracture zones. During measurements in Stripa reflections from fracture zones have been observed more than 100 m from the borehole.

Interplay of Soret vs. Normal Impurity Diffusion During Laser or E-Beam Induced Heat Flow Transients in Metals

ABSTRACTIn the growing amount of the experimental data on the diffu sion processes of implanted impurities in a metal sample irradiated by highly energetic and very short pulses, some order may be introduced by the knowledge of the structure of induced thermal transient. The differences in such a structure due to two different energy sources (laser and electron beam) are de scribed with reference to the conditions under which Soret diffusion may be experimentally observed as distinct from nor mal diffusion. Laser induced transient seem to offer this possibility.Some previously reported diffusion processes in laser irra diated systems are reinterpreted on this basis, showing the importance of the Soret effect.