A. Zehe

Chemical CdS Thin‐Film Deposition Influenced by External Electric and Magnetic Fields

Cadmium sulfide polycrystalline thin films were grown on glass substrates by the chemical-bath deposition technique (CBD) under application of both a pulsating direct electric and a dc magnetic field acting on the Cd- and S-ions during growth in an aqueous solution which contains CdCl 2 and thiourea as source material for the cadmium and sulfur components, respectively. The field orientation in each case of deposition was chosen perpendicular as well as parallel to the growing CdS-film interface. Two different values of the magnetic field strength were applied. Various properties of the films were studied, such as optical transmission and reflection, surface morphology, X-ray diffraction, and dark electrical resistivity, as a function of the applied field configurations, which reveal a clear effect of the field presence during growth.

Mathematical modeling of electro-rotation spectra of small particles in liquid solutions: Application to human erythrocyte aggregates

Electro-rotation can be used to determine the dielectric properties of cells, as well as to observe dynamic changes in both dielectric and morphological properties. Suspended biological cells and particles respond to alternating-field polarization by moving, deforming or rotating. While in linearly polarized alternating fields the particles are oriented along their axis of highest polarizability, in circularly polarized fields the axis of lowest polarizability aligns perpendicular to the plane of field rotation. Ellipsoidal models for cells are frequently applied, which include, beside sphere-shaped cells, also the limiting cases of rods and disks. Human erythrocyte cells, due to their particular shape, hardly resemble an ellipsoid. The additional effect of rouleaux formation with different numbers of aggregations suggests a model of circular cylinders of variable length. In the present study, the induced dipole moment of short cylinders was calculated and applied to rouleaux of human erythrocytes, which move freely in a suspending conductive medium under the effect of a rotating external field. Electro-rotation torque spectra are calculated for such aggregations of different length. Both the maximum rotation speeds and the peak frequencies of the torque are found to depend clearly on the size of the rouleaux. While the rotation speed grows with rouleaux length, the field frequency nu(p) is lowest for the largest cell aggregations where the torque shows a maximum.

Formation of CdS thin films in a chemical bath environment under the action of an external magnetic field

External magnetic fields were applied during thin film preparation of CdS on glass substrates by the chemical bath deposition technique (CBD). Some physical properties of the polycrystalline films, like layer thickness, grain size and optical quality depend in a characteristic manner on the strength and orientation of the external field during the growth process. The characterization of the samples includes atomic force microscopy (AFM), optical absorption, and dark conductivity measurements. The data interpretation follows a line based on the specific interaction of cadmium and sulfur ions with acting magnetic fields within the chemical bath

Options for the Development of Noninvasive Glucose Monitoring: Is Nanotechnology an Option to Break the Boundaries?

Nowadays nanotechnology has many applications in products used in various areas of daily life; however, this technology has also an option in modern medicine and pharmacy. Therefore, this technology is also an attractive option for the field of diagnosis and treatment of diabetes. Many people with diabetes measure their blood glucose levels regularly to determine the insulin dose. Ideally glucose values would be measured noninvasively (NI). However, none of all the NI approaches studied in the past decades enabled reliable NI measurements under all daily life conditions. Particularly an unfavorable signal-to-noise ratio turned out to be problematic. Based on the known physical possibilities for NI glucose monitoring the focus of this review is on nanotechnology approaches. Functional prototypes exist for some of these that showed promising results under defined laboratory conditions, indicating a good sensitivity and selectivity for glucose. On the second hand is to optimize the technological process of manufacturing. In view of the rapid progress in micro- and nanoelectronics hopefully NI glucose monitoring systems can be developed in the near future.

Dependence of dielectrophoretic force on the size of linear erythrocyte aggregates in suspension

For modeling of erythrocyte rouleaux (linear cell aggregates) we develop an approximation procedure for the dipole moment in short cylinders, which contains the case of ellipsoidal bodies as a first approximation, but allows corrections for short cylinders, more representative for such particles. In dependence on the number of erythrocytes in an aggregation, i.e., on different but discrete rouleaux lengths, the dielectrophoretic force is calculated and represented against the frequency of the applied AC field. Predictions are made for frequency regions in the 107–108 Hz range where the magnitude and the direction of dielectrophoretic forces is different for different rouleaux sizes. This property can be used for the detection and spatial separation of rouleaux populations of different length in a microelectronic array.

Novel Algorithms for Estimating Motion Characteristics within a Limited Sequence of Images

Abstract. Two novel algorithms for estimating the motion characteristics of the object in dynamic scene by processing a limited sequence of images are presented in this paper. The first algorithm is based on computation of space-temporal gradients of consecutive frames of video stream, another one has been designed for fast detection of motion by processing of principal corners of objects in real time applications. For quantitative estimation of motion characteristics, the novel segment and neighbours matching technique has been proposed. The method uses the concept of fuzzy sets and membership functions, which permits high-speed recognition and efficient interpretation of the patterns with significant level of noise and distortions. The introduced algorithms have been tested in order to evaluate their velocity, utility and efficiency.

Nanotechnological Approach to the Treatment of Diabetes

Nanotechnology in diabetes research has facilitated the evolution of novel glucose measurement and insulin delivery systems. As type 1 diabetes mellitus needs treatment with insulin from the very beginning on, the objective of any kind of diabetes therapy is to reach nearly physiological glucose levels. The current view points toward a continuous insulin infusion by means of an insulin pump. It is desirable then, that a glucose sensor would automatically control the insulin supply, given that an insulin pump works only manually. Worldwide diabetes research activities at its interface with nanotechnology have created devices at the micro- or nanoscale by which the experimental approach toward an artificial pancreas is already put in practice. The article discusses some aspects of conventional glucose sensors, as well as basic concepts and developments in the field of nanotechnology and their application in the field of diabetes research. Some types of nanoscale sensors and functionalized nanostructures as insulin-delivery systems are looked at, that could act as an artificial pancreas.

Novel algorithm for motion prediction invariant to rotation and occlusion

A novel algorithm for motion estimation and prediction of objects in dynamic scenes by processing a limited sequence of images is presented in this paper. The proposed hybrid algorithm is based on computing differences between consecutive frames of video streams for fast detection of objects in motion by processing of their time-varying edges in real time applications. For quantitative prediction of motion and computing of its characteristics, the interpolation technique has been used in combination with the motion stabilization technique useful for analysis of irregular displacement of objects. The principal goal of the proposed algorithm is the design of simple but efficient facilities for motion prediction when the possible routes may be quickly computed even with occlusions and rotation. The introduced algorithm has been tested in order to evaluate its utility and performance.

Electromigration of Aluminium through Quasi Bamboo-Like Grain Blocked Silicide Interconnects

MoSi 2 interconneets between electrical aluminium contact pads were exposed to a high direct current density of 1 MA cm -2 during 2000 hours. Thermal annealing of the interconnects prior to the experiment generated grains of almost the width of the line, providing for bamboo-like grain blocked polycrystalline clusters along the line acting as migration stopping sites. Aluminium migration out of the cathode contact pad is observed with pronounced precipitations on the interconnect side walls. SEM and EDX are applied to identify sites and nature of the electromigration product.

Single Crystalline GexSi1-x Compound Formation by Energetic Ge+-Ion Implantation into Silicon Wafers

Single crystalline Si(111) samples were alloyedby a bombardment of both 60 and 200 keV energetic Ge+ ions. The implantation dose was variedbetween 1014 and 1017 cm-2. Rutherford backscattering and channeling analysis was applied in order to study the formation of a single crystalline Si–Ge alloy layer, both prior and after a thermal treatment at a temperature of 900 Ĉ. Thethickness and the depth of the implanted layer, as well as their composition and crystalline quality was determined, and it was found that a single crystalline Si–Ge alloy layer was created, with both depth and composition depending on the ion energy and the ion dose.