Thermal needle probe

Asher, G.B., Development of a Computerized Thermal Conductivity Measurement System Utilizing the Transient Needle Probe Technique An Application to Hydrates in Porous Media, Dissertation, Colorado School of Mines, Golden, CO (1987). 

Ross and Andersson (1982) suggested that this behavior, which was never before reported for crystalline organic materials, was associated with the properties of glassy solids. Waite et al. (2005) measured the temperature dependence of porous methane hydrate thermal conductivity. Early work on this anomalous property led to the development of a thermal conductivity needle probe (Asher et al., 1986) as a possible means of in situ discrimination of hydrates from ice in the permafrost. 

FIGURE 6.7 Schematic of the pressure vessel and needle probe system used to measure thermal conductivity. (Reproduced from Waite, W.F., deMartin, B.J., Kirby, S.H., Pinkston, J., Ruppel, C.D., Geophys. Res. Lett., 29, 2229 (2002). With permission from the American Geophysical Union.)... 

Asher, GB., Development of a Computerized Thermal Conductivity Measurement System Utilizing the Transient Needle Probe Technique An Application to Hydrates in Porous Media, Dissertation, Colorado School of Mines, Golden, CO (1987). Ashworth, T., Johnson, L.R., Lai, L.P., High Temperatures-HighPressures, 17,413 (1985). Avlonitis, D., Multiphase Equilibria in Oil-Water Hydrate Forming Systems, M.Sc. Thesis, Heriot-Watt University, Edinburgh, Scotland (1988). 

FIGURE 9.1 Principle of divided bar (left) and needle probe (right) technique for determination of thermal conductivity. 

Radiofrequency thermal ablation (RFTA) S. Rossi et al. (1990, 1993) were the first to introduce this procedure. Under analgosedation and local anaesthesia, an expandable, cooled-tip needle electrode is inserted per-cutaneously into the tumour with the help of US, CT or MR guidance. There are various types of probes with some differences. Due to high-frequency alternating current (480-500 kHz), the tumour tissue is gradually heated (up to max. 105 °C). A necrosis voume of 4(-5) cm in diameter can be achieved. An indication is given for 1-3 foci, each with a maximum size of 5 cm in diameter. This also applies to compromised liver func-... 

A field emission source uses a needle-like tungsten or carbon tip as the cathode, shown in Fig. 14.28. The tip is only nanometers wide, resulting in a very high electric field at the tip. Electrons can tunnel out of the tip with no input of thermal energy, resulting in an extremely narrow beam of electrons. Electron beams from heated filaments have a focal (cross-over) diameter of about 50 p,m while a field emission source has a crossover diameter of only about 10 nm. Field emission sources can serve as probes of surfaces at the nanometer scale (an Auger nanoprobe). 

Nevertheless, based on the principle of cauterization, the coagulative potential of the thermal ablation procedure itself makes the bleeding of a treated lesion quite unusual. To avoid needle track bleeding it is recommended to perform hot probe repositioning and removal (i.e. needle track ablation). Therefore, regarding the present literature bleeding in total is a rare, in most cases self-limiting, complication with a frequency of no more than 2%. 

CT guidance affords the best available visualization of needle and probe placement in the lesion nidus. Helical CT with low-dose and CT fluoroscopy makes for a quicker procedure and a lower patient dose (Silverman et al. 1999 Teeuwisse et al. 2001). Lesion size and the configuration of the thermal lesion in particular can he controlled directly during the procedure. Therapy strategy can he adjusted hy the operator during the procedure and provides an effective thermal ablation and therapy result. However, the complication rate is reduced... 

Insert the syringes into the thermal block, keeping the guide pins pointed away from the probe. Turn on the Null Detector switch (Note 6). Set the sensitivity control to sufficient gain so that a 1.0-12 shift in the Dekastat produces one major division shift of the meter needle. 

AFM is a scaiming probe technique, wherein a sharp needle mounted on a flexible cantilever scans across the substrate and probes interactions between the needle tip and the substrate (Figure 1(a)). These force interactions are the basis of all AFM-related modes that are used for the examination of surface stmcture and local physical properties. The interaction forces, regardless of their physical nature, are measured through deflection of the cantilever. These include van der Waals, Coulomb, magnetic, solvation, capillary, and indentation forces. Even thermal noise of a free cantilever can be detected. Due to the universal character of the tip-sample interactions, AFM found widespread applications in materials science. Yet, AFM pays a heavy price for this universality as it obscures the... 

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