Percutaneous radiofrequency thermal lumbar sympathectomy and its clinical use

Percutaneous radiofrequency thermolesion techniques are commonly used in the treatment of chronic pain in different pain syndromes. There are many reports describing techniques of percutaneous radiofrequency thermolesion for denervation of central & spinal nerves (Mullan 1963), 1965, 1971; Rosomoff, 1966, Sweet 1974, Uematsu, 1974). Apart from the report by Pernak (1985) no other clinical studies concerning the use of the radiofrequency electrocoagulation technique for denervation of sympathetic nerves have been reported in the literature. For sympathetic denervation, neurolytic agents or surgical sympathectomy are still commonly performed and these techniques may provide prolonged pain relief (Swerdlow, 1978). Poor results occur when technical difficulties result in an incomplete sympathectomy. Neurolytic sympathectomy, using phenol or alcohol, offers the advantage of short hospitalisation and avoids the risk of surgery and need for anesthesia. Nevertheless, following both surgical and chemical sympathectomy the possibility of complications is always present (Swerdlow, 1978; Rutherford, 1977). Taking this into consideration, we have performed and developed the technique of radiofrequency thermal sympathectomy from 1982 to date. The first presentation of this technique took place at the 1st International Symposium 'The Pain Clinic' (Delft, 1984) and is described in the Proceedings of that symposium (Pernak and v.d. Berg, 1985). Slight modifications to this technique have since been made which will be outlined in this report. Knowledge of the course of the sympathetic innervation provided the idea to perform thermal radiofrequency sympathectomy at the 4th lumbar level only. However, in different pain syndromes radiofrequency sympathectomy can be performed at every level of the spine. Thermal sympathectomy can be used in those pain syndromes where hyperactivity of the sympathetic nerves is obvious. To date, more than 500 percutaneous radiofrequency thermal sympathectomies have been performed in patients with varying pain syndromes. In this study, 210 patients with different pain syndromes were selected and one criterion for selection was that all patients had obvious sympathetic hyperactivity. Percutaneous radiofrequency thermal lumbar sympathectomy (PRTLS) was performed in all these patients. This technique is described and its clinical use in the combined pain treatment of these patients in the Pain Clinic of the Reinier de Graaf Gasthuis in Delft during the period 1983-1986 is discussed. The results and conclusions are presented

Solvent-free ionic liquids as in situ probes for assessing the effect of ion size on the performance of electrical double layer capacitors

The authors thank Norit for kindly supplying the activated carbon adsorbent. COA thanks MEC, Spain, for the financial support (EX2004-0612). Poznań University of Technology is also acknowledged (Project DS 32/007/2005). The help of Dr. Parra with the Modelling Software and of Dr. Khomenko in the conductivity measurements is acknowledged.Peer reviewe

Stratified and Buoyancy-Induced Flow in Closed Compressor Rotors

The radial growth of compressor discs is strongly influenced by conjugate heat transfer between conduction in the co-rotating discs and buoyancy-driven convection in the rotating fluid core between the discs. An accurate prediction of metal temperatures of these discs is an important issue in thermo-mechanical design, where blade-tip clearances must be controlled carefully to ensure safety and efficiency under all operating conditions. This paper presents an experimental study of the fluid dynamics and heat transfer in a closed rotating cavity, comparing results with theoretical models and introducing a new compressibility parameter X. At large values of X, where compressibility effects are significant, the air temperature approaches that of the shroud; such conditions suppress buoyancy effects and the flow in the rotating cavity becomes stratified, with convection replaced by conduction inside the fluid core. There are important practical consequences of stratification with significant differences in temperature distributions and stresses inside compressor discs. The influence of X is also shown on the radial temperature distributions for the discs and on the shroud heat transfer correlations, which are compared qualitatively with previously published data collected where the effects of compressibility are relatively small. The experiments reveal that there is a critical value of X where the convective heat flux to the shroud is zero. The radial distribution of disc temperature was that expected from pure conduction in a cylinder. A new heat transfer correlation based on measured shroud heat flux and the theoretical core temperature is presented. The unsteady flow characteristics in the cavity were also investigated, identifying coherent rotating structures across a range of experimental conditions. These cyclonic/anticyclonic vortex pairs generate the nondimensional circumferential pressure difference necessary for the radial outflow (of cold fluid) and inflow (of hot fluid) through the rotating core. The experiments show that the magnitude of these pressure variations can be correlated against Grashof number and at high values of X the structures do not exist. The combined experimental and theoretical results will be of practical interest to engine designers and for the validation of computational models.</p

Synthesis and Biocidal Activity of Some Naphthalene-Based Cationic Surfactants

In this study, different cationic surfactants were prepared by reacting dodecyl bromide with tertiary amines to produce a series of quaternary ammonium salts that were converted subsequently to stannous and cobalt cationic complexes via complexing them with stannous (II) or cobalt (II) ions. Surface properties such as surface- and interfacial-tension, and the emulsifying power of these surfactants were investigated. The surface parameters including critical micelle concentration, maximum surface excess, minimum surface area, tension lowering efficiency and effectiveness were studied. The free energy of micellization and adsorption were calculated. Antimicrobial activity was determined via the inhibition zone diameter of the prepared compounds, which was measured against six strains of a representative group of microorganisms. The antimicrobial activity of some of the prepared surfactants against sulfate reducing bacteria was determined by the dilution method. FTIR spectra, elemental analysis and a H1 NMR spectrum were examined to confirm compound structure and purity. The results obtained indicate that these compounds have good surface properties and good biocidal effect on broad spectrum of micro organisms

Alkyltributylphosphonium chloride ionic liquids: synthesis, physicochemical properties and crystal structure

[EN] A series of alkyltributylphosphonium chloride ionic liquids, prepared from tributylphosphine and the respective 1-chloroalkane, CnH2n+1Cl (where n = 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12 or 14), is reported. This work is a continuation of an extended series of tetraalkylphosphonium ionic liquids, where the focus is on the variability of n and its impact on the physical properties, such as melting points/glass transitions, thermal stability, density and viscosity. Experimental density and viscosity data were interpreted using QPSR and group contribution methods and the crystal structure of propyl(tributyl) phosphonium chloride is detailed.This work was funded by Cytec Canada, Inc. G.A. would like to thank Dr Douglas Harris (Cytec) for fruitful comments and advice at the beginning of this work; Prof. Chris Strauss, Dr Markus Fanselow and Dr Giulia Fiorani for microwave assistance and helpful guidance, and Prof. P.R. Raithby for the X-ray diffraction data collection. L.P.N.R. thanks Fundacao para a Ciencia e Tecnologia, Portugal, for support under grants PTDC/QUI-QUI/101794/2008 and PTDC/QUI/71331/2006.Adamova, G.; Gardas, RL.; Nieuwenhuyzen, M.; Vaca Puga, A.; Rebelo, LPN.; Robertson, AJ.; Seddon, KR. (2012). Alkyltributylphosphonium chloride ionic liquids: synthesis, physicochemical properties and crystal structure. Dalton Transactions. 41(27):8316-8332. doi:10.1039/c1dt10466gS83168332412

Thermal and mechanical properties of chitosan nanocomposites with cellulose modified in ionic liquids

In this paper, ionic liquid treatment was applied to produce nanometric cellulose particles of two polymorphic forms. A complex characterization of nanofillers including wide-angle X-ray scattering, Fourier transform infrared spectroscopy, and particle size determination was performed. The evaluated ionic liquid treatment was effective in terms of nanocrystalline cellulose production, leaving chemical and supermolecular structure of the materials intact. However, nanocrystalline cellulose II was found to be more prone to ionic liquid hydrolysis leading to formation larger amount of small particles. Each nanocrystalline cellulose was subsequently mixed with a solution of chitosan, so that composite films containing 1, 3, and 5% mass/mass of nanometric filler were obtained. Reference samples of chitosan and chitosan with micrometric celluloses were also solvent casted. Thermal, mechanical, and morphological properties of films were tested and correlated with properties of filler used. The results of both, tensile tests and thermogravimetric analysis showed a significant discrepancy between composites filled with nanocrystalline cellulose I and nanocrystalline cellulose II