Eradication of Barrett''s mucosa with argon plasma coagulation and acid suppression: immediate and mid term results

Microcapsules are used for the formulation of drug controlled release and drug targeting dosage forms. Encapsulated hydrophobic drugs are often applied as their solutions in plant oils. The uptake of the oils in the complex coacervate microcapsules can be improved by the addition of surfactants. In this study, soybean, olive and peanut oils were chosen as the representatives of plant oils. The well characterized complex coacervation of gelatin and acacia has been used to produce the microcapsules. The amount of encapsulated oil has been determined gravimetrically. The encapsulation of the oils was high (75-80%). When the surfactants with HLB values from 1.8 to 6.7 were used, the amount of encapsulated oil was high (65-85%). A significant decrease of the oil content in the microcapsules was found when Tween 61 with HLB = 9.6 had been added into the mixture. No oil was found inside the microcapsules from the coacervate emulsion mixture containing Tween 81 (HLB = 10) and Tween 80 (HLB = 15), respectively. The results of the experiment confirm the dependence of hydrophobic substance encapsulation on the HLB published recently for Squalan.     

Determination of tryptophan in feedstuffs: Comparison of two methods of hydrolysis prior to HPLC analysis

The tryptophan content of nine samples of commercial feed was determined using two procedures (I and II) differing mainly in the hydrolysis conditions used prior to analysis. With I, hydrolysis was performed with 4 M LiOH in the presence of maltodextrin with 5-methyltryptophan used as internal standard at 110°C for 24 h; with II. oxygen-free 1.3 M Ba(OH)₂ was used at 125°C for 16 h. The two procedures gave identical results for a given sample indicating that the corrections for the incomplete recovery of tryptophan 5-methyltryptophan quantitation were satisfactory.     

Raman microprobe analysis of preforms and optical fibers

The concentration profile of various dopants (germanium, phosphorus, and fluorine) in preforms and optical fibers has been obtained with a Raman microprobe. A 2-microm spatial resolution was achieved. In the case of germanium and phosphorus, the results agree quite well with those obtained with an electron microprobe. Raman spectroscopy easily detects fluorine. From measurements of various F-doped samples, diffusion of fluorine in undoped and doped silica is suggested.     

Quelques remarques sur la generation et la mesure des spheres de latex polystyrene

The main results obtained when dispersing spheres of polystyrene latex are given. The ratio of particles to latex suspension, under different conditions of generation, was evaluated by means of a condensation nucleus counter and a Royco spectrometer. The retention of spheres of latex by diffusion batteries and systems of channels is affected by the electric charge on the particles. Neutralisation of the charge and making the particles radioactive results in the formation of a number of parasitic particles.     

Identification of synchronous machines parameters using broadbandexcitations

This paper describes a newly developed measurement and identification technique for synchronous machine parameters. The first part presents a technique to generate periodic broadband power signals with a controllable amplitude spectrum using a classic rectifier bridge. These signals are well suited to measure the frequency response function of large power systems using the fast Fourier transform. The broadband measurements are compared with the classical mono frequency measurements. The second part presents a frequency domain identification method taking into account the uncertainty on all the current and voltage measurements, and giving a confidence interval on the estimated synchronous machine parameters. As an illustration the d- and q-axis model of a 1.905 kVA/220 V micro-machine is identified     

Surface strain measurements of fingertip skin under shearing

The temporal evolution of surface strain, resulting from a combination of normal and tangential loading forces on the fingerpad, was calculated from high-resolution images. A customized robotic device loaded the fingertip with varying normal force, tangential direction and tangential speed. We observed strain waves that propagated from the periphery to the centre of the contact area. Consequently, different regions of the contact area were subject to varying degrees of compression, stretch and shear. The spatial distribution of both the strains and the strain energy densities depended on the stimulus direction. Additionally, the strains varied with the normal force level and were substantial, e.g. peak strains of 50% with a normal force of 5 N, i.e. at force levels well within the range of common dexterous manipulation tasks. While these observations were consistent with some theoretical predictions from contact mechanics, we also observed substantial deviations as expected given the complex geometry and mechanics of fingertips. Specifically, from in-depth analyses, we conclude that some of these deviations depend on local fingerprint patterns. Our data provide useful information for models of tactile afferent responses and background for the design of novel haptic interfaces.     

Epitaxial growth of LaAlO3 on Si(0 0 1) using interface engineering

In this work, the potentiality of molecular beam epitaxy techniques to prepare epitaxial lanthanum aluminate (LaAlO₃) films on Si(0 0 1) is explored. We first demonstrate that the direct growth of LaAlO₃ on Si(0 0 1) is impossible : amorphous layers are obtained at temperatures below 600 °C whereas crystalline layers can be grown at higher temperatures but interfacial reactions leading to silicate formation occur. An interface engineering strategy is then developed to avoid these reactions. SrO and SrTiO₃ have been studied as buffer for the subsequent growth of LaAlO₃. Only partial LaAlO₃ epitaxy is obtained on SrO whereas high quality layers are achieved on SrTiO₃. However both SrO and SrTiO₃ appear to be unstable with respect of Si at the growth temperature of LaAlO₃ (700 °C). This leads to the formation of relatively thick amorphous interfacial layers. Despite their instability at high temperature, these processes could be used for the fabrication of twins-free LaAlO₃ templates on Si, and for the fabrication of complex oxide/Si heterostructures for various applications.     

A 0.4-μm gate-length AlGaAs/GaAs P-channel HIGFET with 127-mS/mmtransconductance at 77 K

WN-gate, p-channel AlGaAs-GaAs heterostructure insulated-gate field-effect transistors (HIGFETs) fabricated on a metalorganic vapor-phase epitaxy (MOVPE) wafer are discussed. A self-aligned Mg ion implantation (80 keV, 6×10¹³ cm^-2) annealed at 850°C in an arsine atmosphere and the control of the SiO₂ sidewall dimensions allow the fabrication of p-channel HIGFETs with a gate length smaller than 0.5 μm with low subthreshold current. P-channel HIGFETs with 0.4-μm gate lengths exhibit extrinsic transconductances as high as 127 mS/mm at 77 K and 54 mS/mm at 300 K     

Photoemission (XPS and XPD) study of epitaxial LaAlO3 film grown on SrTiO3(0 0 1)

This study investigates the tensile-strained growth of LaAlO₃ on SrTiO₃(0 0 1) substrate by molecular beam epitaxy (MBE). Growth was controlled in situ by reflection high energy electron diffraction (RHEED). The characterization was carried out ex situ by photoemission and atomic force microscopy (AFM). Photoelectron spectroscopy (XPS) reveals the development of a TiO_x-rich interface. Photoelectron diffraction (XPD) confirms that a 1.2-nm-thick pseudomorphic LaAlO₃ film has been grown on SrTiO₃(0 0 1) substrate with a perpendicular lattice parameter of 0.372±0.02 nm.     

Influence of stress state and strain rate on the behaviour of a rubber-particle reinforced polypropylene

This article presents an experimental investigation of a ductile rubber-modified polypropylene. The behaviour of the material is investigated by performing tension, shear and compression tests at quasi-static and dynamic strain rates. Subsequently, scanning electron microscopy is used to analyse the fracture surfaces of the tension test samples, and to relate the observed mechanical response to the evolution of the microstructure. The experimental study shows that the material is highly pressure and strain-rate sensitive. It also exhibits significant volume change, which is mainly ascribed to a cavitation process which appears during tensile deformation. Assuming matrix-particle debonding immediately after yielding, the rubber particles might play the role of initial cavities. It is further found that the flow stress level is highly dependent on the strain rate, and that the rate sensitivity seems to be slightly more pronounced in shear than in tension and compression. From the study of the fracture surfaces it appears that the fracture process is less ductile at high strain rates than under quasi-static conditions.