Numerical electrodynamic analysis of the far-field patterns of the external Sestroretskii cube

Far-field patterns of the external Sestroretskii cube with the edge size of 1 mm for the frequencies of 1, 150, and 300 GHz are presented. The paradox of the external Sestroretskii cube and its relation to the paradox of the external Huygens cube are revealed.     

Investigation of the degradation mechanisms of InP/InGaAs DHBT under bias stress conditions to achieve electrical aging model for circuit design

The reliability of InP/InGaAs DHBT under high collector current densities and low junction temperatures is analyzed and modeled. From the Gummel characteristics, we observe several types of device degradation, resulting from the long term changes of base and collector current in both lower and higher base–emitter voltage ranges which impacts the reduction of DC current gain. In this paper, we investigate the underlying physical mechanism of base and collector current degradation with the help of TCAD device simulation. We chose the HICUM model level2 for the modeling purpose to evaluate the drift of model parameters according to stress time. The evolution of the model parameters is described with suitable equations to achieve a physics based compact electrical aging model. The aging laws and the parameter evolution equations with stress time are implemented in compact electrical aging model which allows us to simulate the impact of device failure mechanisms on the circuit in operating conditions.     

Protein function microarrays based on self-immobilizing and self-labeling fusion proteins

Protein microarrays are an attractive approach for the high-throughput analysis of protein function, but their impact on proteomics has been limited by the technical difficulties associated with their generation. Here we demonstrate that fusion proteins of O6-alkylguanine-DNA alkyltransferase (AGT) can be used for the simple and reliable generation of protein microarrays for the analysis of protein function. Important features of the approach are the selectivity of the covalent immobilization; this allows for direct immobilization of proteins out of cell extracts, and the option both to label and to immobilize AGT fusion proteins, which allows for direct screening for protein-protein interactions between different AGT fusion proteins. In addition to the identification of protein-protein interactions, AGT-based protein microarrays can be used for the characterization of small molecule-protein interactions or post-translational modifications. The potential of the approach was demonstrated by investigating the post-translational modification of acyl carrier protein (ACP) from E. coli by different phosphopantetheine transferases (PPTases), yielding insights into the role of selected ACP amino acids in the ACP-PPTase interaction.     

Analysis of two models of (3D) Fresnel collectors operating in the fixed-aperture mode with a tracking absorber

In this paper, we study the reflection behavior of (3D) Fresnel collectors operating in the fixed-aperture mode with a tracking absorber. The aim of the study is to investigate the possibility of the use of this type of installation for applications in medium temperature processes (200–300°C). Two models of (3D) Fresnel concentrator are developed for this purpose. One is based on the approximation of the optical behavior of a parabolic concentrator, and the other on that of a spherical one. Via a computer simulation which includes ray-tracing, we evaluate the sensitivity of the geometric concentration ratio to concentrator design parameters, and the option of using curved versus flat elementary mirrors. The numerical results show that there is no large difference between the two models of Fresnel concentrator. For the spherical model, which seems to be slightly more suitable for this type of application, we propose a simple solution for the receiver displacement, which consists of a single-sided absorber moving tangentially to a sphere centered in the concentrator’s center.     

Preliminary results of storage accelerated aging test on InP/InGaAs DHBT

We report on the reliability of InP HBT technology which has applications in very high-speed ICs. This work presents the storage accelerated aging tests results performed on InP/InGaAs HBT at stress temperatures of 180, 210 and 240 °C up to 3000 h. We have performed aging tests for two generations of InP HBT which differ from the collector doping level and from material used for planarization. From the Gummel plots, we note that the major degradation mechanism is located at the base–emitter junction periphery. Investigations on the physical origin of the observed failure mechanism has been performed using TCAD simulations.