Analyse et modélisation de la permittivité effective statique de la ligne microruban suspendue

New numerical quasi-static model for the computer aided design (CAD) and analysis of suspended microstrip lines is reported. This model is applicable up to ε_r = 20 and over the range 0.001 ≤ u ≤ 1000, where u = w/h ₁ is the structure’s variable (w is the width of the strip and h ₁ is the air gap’s thickness). The practical cases are limited to a thickness h ₁ of the same order of h ₂ which is the dielectric’s thickness. This yields to choose 0.5 ≤ m ≤ 1.5. The parameter m is dependent on the structure’s variable u. This model is conceived to corroborate the results of the variational approach in any point of its ranges of validity, with a raised error with 1.2%. Although the variational approach allows accurate values of the effective permittivity, but the computing time is relatively high which quickly becomes prohibitory if the Finished Coupled Elementary Lines method is used. The present model is an improvement over the previous variational method as it not only takes lower computing time but it also valid up to high values of ε_r and over the range 0.001 ≤ u ≤ 1000. This work is important by the fact that it seeks to visualise the formal model of the effective permittivity, generally masked in a direct variational treatment.     

Synchronous thermal wave IR video imaging for nondestructive evaluation

We describe a system for real-time processing of infrared video images in synchronism with the time-dependence of the target object's temperature. The system can either be used either with periodic or pulsed heating of the target. With periodic heating, the system operates as if it were a collection of lock-in amplifiers, one for each of the quarter of the million pixels of the image. With pulsed heating, it operates as if it consisted of a similar number of box-car averagers. In both cases, the signal-to-noise ratio and temperature sensitivity of the infrared camera are improved. The technique lends itself to a wide spectrum of NDE applications.     

Re-examination of a proposed model for nonisothermal crystallization kinetics

This communication is a theoretical re-examination of the model proposed by Choe and Lee for the nonisothermal crystallization kinetics of semicrystalline polymers.     

Oestradiol-17 beta modulates PAF-evoked phospholipase D activity but not inositide-lipid hydrolysis in human endometrial cell line, HEC-1B

The skeleton of a middle-aged adult male, found in the Late Epigravettian necropolis of Arene Candide cave (Italy) and dated to the XII millennium B.C., exhibits abnormal changes, including bowing deformities, stunted growth, enthesopathies, and increased bone density. The pattern of the observed changes is less consistent with diagnoses of metaphyseal chondrodysplasias, hypophosphatasia, dietary rickets, or diffuse idiopathic skeletal hyperostosis (DISH) than with X-linked hypophosphatemic rickets, which is the most likely etiological factor. This diagnosis may explain other abnormalities (exceptional elongation of the skull and bilateral absence of the lesser trochanter) displayed by other individuals from the same site.     

Synthesis of poly(methylmethacrylate)/montmorillonite nanocomposites via in situ intercalative suspension and emulsion polymerization

Summary Na-montmorillonite (MMT) with cation exchange capacity (CEC) of 90 mEq/100g was converted to MMT-CTAB and MMT-CPC forms by the intercalation of Cetyltrimethylammonium bromide (CTAB) and Cetylpyridinium chloride (CPC), respectively. The intercalation of these surfactants onto the basal space of the montmorillonite was evidenced by fourier transform infrared spectroscopy (FTIR) and x-ray diffraction (XRD). The intercalation of the CPC expanded the basal space from 12.19 A^o to 21.47 A^o while in case of CTAB it was expanded to 19.35 A^o only. The (MMT-CPC) was subsequently used as a host for the preparation of PMMA nanocomposites via intercalative suspension and emulsion polymerization of methylmethacrylate (MMA) using benzoyl peroxide (BPO) and potassium persulphate (PPS) individually and simultaneously. The use of BPO and PPS together invoked better exfoliation but the yield did not change appreciably in comparison with using either of the initiators alone. Different structures were obtained with the variation of the preparation conditions; exfoliated and intercalated nanocomposites which were characterized by XRD, transmission electron microscope (TEM), thermal gravimetric analysis (TGA), and differential scanning calorimeter (DSC). The resultant nanocomposites exhibited improved thermal stability relative to the equivalent macrocomposites. No glass transition temperature (Tg) could be detected for the prepared nanocomposites which was assumed to result from the restricted molecular motion of the polymer chains.     

Comparison of the performance of selected powder and masterbatch pigments on mechanical properties of mass coloured polypropylene filaments

No suitable method for the coloration of unmodified polypropylene using aqueous dye solution has yet been found. Currently, the only viable method is the incorporation of pigments during the extrusion of filaments. In this study, two different commercially available forms of pigment (powder and masterbatch) were incorporated into polypropylene before extruding into filaments to examine their effects on the mechanical behaviour of the filaments. It was found that increasing the pigment content generally reduces tensile strength and Young's modulus in both masterbatch-pigmented filaments and powder-pigmented filaments. However, the extent of reduction is also markedly dependent on the type of pigment incorporated. In addition, elongation to peak is much higher for masterbatch-pigmented filaments than for powder-pigmented filaments.     

Triple therapy in duodenal ulcer healing--a follow up study

Thirty-nine Helicobacter pylori (HP) positive chronic duodenal ulcer patients completed the 4 weeks treatment of triple therapy (Denol, Metronidazole and Amoxil). Of these 29 showed healed duodenal ulcer and negative CLO test at 8 weeks (eradication). They were followed at 3,6 and 12 months and at each follow-up, endoscopy and CLO testing were repeated. At 12 weeks, 54% showed a healed ulcer and negative CLO and these figures reached to 69 and 66% at 6 and 12 months respectively. Thirty percent relapsed within 1 year. The present study indicates a prolonged remission of duodenal ulcer following HP eradication.     

Non-intubated pyeloplasty for pelviureteric junction obstruction in children

Sixty-one consecutive patients undergoing pyeloplasty (5 bilateral) were reviewed retrospectively; 54 pyeloplasties were non-intubated (NIP) and 12 were intubated. NIPs were managed by an extrarenal wound drain, which was removed after 2-4 days in 44 repairs with minimal or no urinary leakage and after 6-8 days in 10 with significant leakage. Fifty-two were successful after the primary procedure. One patient who developed a urinoma after drain removal required a percutaneous nephrostomy followed by a revision pyeloplasty. A second revision pyeloplasty was necessary for persistent postoperative obstruction. The results of NIP compared favorably with series where intubation was used routinely and were superior to alternative methods of management such as endopyelotomy.     

Testing of highly loaded horizontal axis wind turbines designed for optimum performance

The realization of a wind turbine as a source of clean, non-polluting and renewable energy may depend on the optimum design of turbine blades that can operate efficiently under extreme variations in wind conditions. In this paper we provide results of an experimental investigation to examine the effectiveness of a highly loaded theory for the design of a horizontal axis wind turbine for optimum power production over a wide range of advance ratios. We find the theory, which can be used to set up design curves easily and requires only hand held calculator for calculation, offers a rational basis for the design of propeller wind turbines for peak performance.