Interferometric investigation of the opto-mechanical and structural properties of iPP/TiO2 nanocomposite fibers.

Fibers that missing specific features and functionalities could be innovated and functionalised via nano additives, in particular metal oxides. Titanium oxide (TiO2 ) nanoparticles have been added to isotactic polypropylene (iPP) to form iPP/TiO2 nanocomposite fibers. Three samples of iPP/TiO2 fibers were extruded at three extrusion speeds 25, 50, and 78 m/min were considered in this study. Mach-Zehnder interferometer was used to assess the changes in the opto-mechanical and geometrical parameters of iPP/TiO2 nanocomposite fibers along the fiber axis. The mechanical drawing device along with Mach-Zehnder interferometer was utilized to stretch the filaments to different draw ratios. The effect of mechanical cold drawing and extrusion speed on the optical and physical characteristics of iPP/TiO2 nanocomposite fibers were determined along the fiber axis. The optical and physical variation along the nanocomposite samples were characterized by measuring their refractive indices, birefringence, refractive index profile along the fiber axis. The diffraction of He-Ne laser beam was used to define the variation of the fiber diameter along the fiber axis through their cross-sectional area and shape. A sample of uniform diameter from neat iPP fibers was used as reference material for studying the variation of the iPP/TiO2 fiber diameter along the fiber axis. As result, the iPP/TiO2 nanocomposite fibers exhibited nonuniform diameters. The dispersion of TiO2 particles in nanocomposite fibers influences the properties' consistency along and across the fiber.

A novel dynamic opto-thermo-mechanical stress testing device 2: In situ stretching process of polymeric fibers.

In this article, we used the opto-mechanical stress testing-device to stretch a monofilament of isotactic Polypropylene, iPP, fibers. This device was used to obtain the mechanical behavior of these fibers by measuring the complete stress-strain curves at different stretching conditions. Using this device, the different regions of iPP fiber where the mechanical deformation takes place was characterized, including the necking region and fracture initiation process. The obtained mechanical behavior of iPP fibers was correlated to the variations of different optical parameters by attaching the device with the Pluta polarizing interference microscope. This microscope and the stress device allowed us to simultaneously measure the optical parameters and stress-strain data during stretching process at different stretching speeds. These data provide us with comprehensive information on the opto-mechanical behavior of polymeric fibers. Interferograms are included for illustration. The opto-mechanical stress testing-device was used to stretch a monofilament of, iPP, fibers. The mechanical deformation takes place was characterized, including the necking region and fracture initiation process at different stretching speeds.

Characterization of the 3Dimension optical, geometrical, and mechanical profiles of iPP fiber with necking deformation.

We present a method for evaluating the 3D refractive indices and 3D true stress and/or 3D true strain profiles of "isotactic polypropylene iPP" fibers during necking deformation. Observing the changes in geometrical shape during the deformation process is necessary to understand the mechanical performance of iPP fibers. 3D geometric shape profile and actual stress and strain profiles were measured for iPP fibers during the propagation of neck deformation. These measurements were performed with the aid of an in-situ opto- mechanical device to dynamically characterize different properties of fibers at different strain rates. A software image analysis program was used to calculate the 3D opto-mechanical properties of iPP fibers. The obtained results show that the used dynamic stretching device can be easily used to monitor the deformation process with high accuracy. The effective stress and strain can be determined from the filaments profile. For illustration microinterferograms are given.

A novel dynamic opto-thermo-mechanical stress testing device 1: Design of the device.

This article presents a dynamic opto-thermo-mechanical stress testing device to characterize fiber properties. The device has multi-modes and consists of many functions. These modes include stretching, bending, rotating, twisting, and heating processes. Every process can be controlled by micro-controller unit via software programs specially designed for this purpose. The micro-controller unit can execute two different processes at the same time. Such as, dynamic stretching process under the effect of thermal treatment, dynamic stretching process and relaxation, bending process under the effect of thermal treatment, and so forth. Software programs with their flow charts are designed for the application of these processes. The advantage of this device is that it can be done statically and dynamically to characterize all types of fibers (polymer and optical). The device is designed to be attached with two-beam polarizing interference microscope to investigate the dynamic opto-thermo-mechanical properties of the tested fiber under the effect of different applied stresses. Isotactic polypropylene, iPP, fiber is used for some applications of this device, as examples, in stretching, rotation, and twisting modes. Interferograms and graphs are given for illustration.

The effect of short heat treatment on different properties of PET fiber using double beam interference microscopy.

Pluta microscope used to throw light on the effect of heat treatment time on the different properties of poly (ethylene terephthalate) PET fibers. PET fibers were annealed at times ranged from 5 to 30 min at different temperatures (150, 170, 190, 210°C) using two different processes (fast cooling and slow cooling processes) in air. The refractive indices, the shrinkage, orientation factor and crystallinity of PET fibers were determined for different annealing temperature during the short time treatment. The shrinkage percentage and degree of crystallinity increased with increasing the temperature and time of annealing. Microinterferograms are given for illustration.

The effect of different thermal treatment on the physical properties of PGA/PCL copolymer suture material.

Samples of polyglycolic acid PGA/polycaprolactone PCL copolymer absorbable suture materials, which is called Poliglecaprone PGC copolymer suture, were thermally treated by two different processes. The first method is the direct heat exposure, from 20 to 38 °C, in the surrounding medium. Which is an environmental study. The other method is the annealing process at temperatures ranged from 65, 80, 100, 120, and 140 °C, for two different duration periods 60 and 120 min. This is an extensive technical study. The refractive indices of thermally treated PGA/PCL copolymer sutures were measured using multiple-beam Fizeau fringes. The birefringence profiles across the suture cross-sections were studied for different annealing conditions. The effect of heat on the polarizabilty per unit volume, dielectric properties, and suture diameter were investigated. The activation energy for the heating processes was calculated using Arrhenius equation. Microinterferograms are given for illustration.

A modified method for accurate correlation between the craze density and the optomechanical properties of fibers using Pluta microscope.

A modified method was suggested to improve the performance of the Pluta microscope in its nonduplicated mode in the calculation of the areal craze density especially, for relatively low draw ratio (low areal craze density). This method decreases the error that is resulted from the similarity between the formed crazes and the dark fringes of the interference pattern. Furthermore, an accurate method to calculate the birefringence and the orientation function of the drawn fibers via nonduplicated Pluta polarizing interference microscope for high areal craze density (high draw ratio) was suggested. The advantage of the suggested method is to relate the optomechanical properties of the tested fiber with the areal craze density, for the same region of the fiber material.

[One step surgery for severe African endocrine exophtalmia: clinical case]. / Chirurgie en un temps d'une exophtalmie basedowienne africaine sévère: présentation d'un cas clinique.

INTRODUCTION: The association hyperthyroidism-exophtalmia is pathognomonic of the Graves disease. Classically, the treatment is based on a pluridisciplinary step-by-step approach with a precise chronology. In some African places, these optimal conditions are not present. When confronted to such particular situations, it can be proposed to treat surgically at the same time the endocrine disease and the ophthalmologic complications. OBSERVATION: The authors report the case of a 42-year-old women suffering of a great thyreotoxic goiter with severe bilateral exophtalmia, treated by thyroidectomy and orbital decompression in the same session with a good result after 18 months. DISCUSSION: This non-conventional approach can be useful in particular situations when the medical environment is not optimal. It permits the radical treatment of their disease and improves the prognosis of patients with poor capacities for survey.

Measuring lymphocyte kinetics in tropical field settings.

Studies involving in-vivo labelling of lymphocyte DNA with 6,6-2H2-glucose to track T-cell turnover have contributed to understanding lymphocyte homeostasis in health and disease. Applying such studies in tropical settings (where diseases that affect T-cells are prevalent) requires protocol modifications including non-intravenous label administration, applicability in outpatient facilities, and T-cell sorting methods independent of a fluorescence activated cell sorter (FACS). Such protocols were validated in UK pilot studies and applied in The Gambia. Healthy adult subjects (n=12) were recruited from three Gambian villages. 6,6-2H2-glucose was administered orally in an outpatient clinic and T-cell subpopulations isolated from peripheral blood using plastic adherence, and Multisorttrade mark magnetic cell sorting (MACStrade mark) to obtain CD8+CD45R0+, CD8-CD45R0+, CD8+CD45R0- and CD8-CD45R0- subsets. To achieve high cell purity and yield, CD45R0- cells were reincubated with CD45R0 beads. T-cell proliferation and disappearance were quantified using gas chromatography mass spectrometry. Results were consistent with those of other studies showing higher turnover in memory (CD45R0+) than in naïve (CD45R0-) T-cell subsets, and an association between recent cell proliferation and susceptibility to cell death. Cell kinetics research is applicable in tropical settings, and can contribute to further understanding the regulation of adaptive immunity in response to infections and other insults.