Stability Improvement of 60 GHz Narrowband Amplifier Using Microstrip Coupled Lines

We present an analysis of microstrip coupled lines (MCLs) used to improve the stability of a 60 GHz narrowband amplifier. The circuit has a 4‐stage structure implementing MCLs instead of metal‐insulator‐metal (MIM) capacitors for the unconditional stability of the amplifier and yield enhancement. The stability parameter, U, is used to compare the stability of MCLs with that of MIM capacitors. Experimental results show that MCLs are more stable than MIM capacitors with the same capacitances as MCLs because the parasitic parallel resistances of MCLs are lower than those of MIM capacitors. Moreover, the bandwidth of an amplifier using MCLs is narrower than one using MIM capacitors because the parasitic series inductances of MCLs are higher than those of MIM capacitors.     

Star-Shaped Poly(furfuryl glycidyl ether)-Block-Poly(glyceryl glycerol ether) as an Efficient Agent for the Enhancement of Nifuratel Solubility and for the Formation of Injectable and Self-Healable Hydrogel Platforms for the Gynaecological Therapies

In this paper, we present novel well-defined unimolecular micelles constructed a on poly(furfuryl glycidyl ether) core and highly hydrophilic poly(glyceryl glycerol ether) shell, PFGE-b-PGGE. The copolymer was synthesized via anionic ring-opening polymerization of furfuryl glycidyl ether and (1,2-isopropylidene glyceryl) glycidyl ether, respectively. MTT assay revealed that the copolymer is non-cytotoxic against human cervical cancer endothelial (HeLa) cells. The copolymer thanks to furan moieties in its core is capable of encapsulation of nifuratel, a hydrophobic nitrofuran derivative, which is a drug applied in the gynaecology therapies that shows a broad antimicroorganism spectrum. The study shows high loading capacity of the copolymer, i.e., 146 mg of nifuratel per 1 g of copolymer. The load unimolecular micelles were characterized using DLS and TEM microscopy and compared with the reference glyceryl glycerol ether homopolymer sample. The presence of numerous 1,2-diol moieties in the shell of PFGE-b-PGG macromolecules enabled the formation of reversible cross-links with 2-acrylamidephenylboronic acid-based polyacrylamide. The obtained hydrogels were both injectable and self-healable, which was confirmed with a rheological study.     

Numerical study of heat transfer and viscous flow in a dual rotating extendable disk system with a non‐Fourier heat flux model

Nonlinear, steady‐state, viscous flow, and heat transfer between two stretchable rotating disks spinning at dissimilar velocities are studied with a non‐Fourier heat flux model. A nondeformable porous medium is intercalated between the disks and the Darcy model is used to simulate matrix impedance. The conservation equations are formulated in a cylindrical coordinate system and via the von Karman transformations are rendered into a system of coupled, nonlinear ordinary differential equations. The emerging boundary value problem is controlled by number of dimensionless parameters, that is, Prandtl number, upper disk stretching, lower disk stretching, permeability, non‐Fourier thermal relaxation, and relative rotation rate parameters. A perturbation solution is developed and the impact of selected parameters on radial and tangential velocity components, temperature, pressure, lower disk radial, and tangential skin friction components and surface heat transfer rate are visualized graphically. Validation of solutions with the homotopy analysis method is included. Extensive interpretation of the results is presented which are relevant to rotating disk bioreactors in chemical engineering.     

Influence of variable viscosity and thermal conductivity,hydrodynamic, and thermal slips on magnetohydrodynamic micropolar flow: A numerical study

Thermophysical and wall‐slip effects arise in many areas of nuclear technology. Motivated by such applications, in this article, the collective influence of variable‐viscosity, thermal conductivity, velocity and thermal slip effects on a steady two‐dimensional magnetohydrodynamic micropolar fluid over a stretching sheet is analyzed numerically. The governing nonlinear partial differential equations have been converted into a system of nonlinear ordinary differential equations using suitable coordinate transformations. The numerical solutions of the problem are expressed in the form of nondimensional velocity and temperature profiles and discussed from their graphical representations. The Nachtsheim‐Swigert shooting iteration technique together with the sixth‐order Runge‐Kutta integration scheme has been applied for the numerical solution. A comparison with the existing results has been done, and an excellent agreement is found. Further validation with the Adomian decomposition method is included for the general model. Interesting features in the heat and momentum characteristics are explored. It is found that a greater thermal slip and thermal conductivity elevate thermal boundary layer thickness. Increasing Prandtl number enhances the Nusselt number at the wall but reduces wall couple stress (microrotation gradient). Temperatures are enhanced with both the magnetic field and viscosity parameter. Increasing momentum (hydrodynamic) slip is found to accelerate the flow and elevate temperatures.     

The adsorption kinetics of metal ions onto different microalgae and siliceous earth

In the present work the adsorption kinetics of the six metal ions aluminum, zinc, mercury, lead, copper, and cadmium onto living microalgae were measured. The freshwater green microalga Scenedesmus subspicatus, the brackish water diatom Cyclotella cryptica, the seawater diatom Phaeodactylum tricornutum, and the seawater red alga Porphyridium purpureum were the subject of investigation. In most cases the adsorption rate of the metals could be well described by using the equation of the Langmuir adsorption rate expression. Inverse parameter estimation allowed the determination of the rate constants of the adsorption process and the maximum metal content of the algae. The highest values for the rate constant were obtained for Porphyridium purpureum followed by Phaeodactylum tricornutum. High values for the maximum content were obtained for Cyclotella cryptica and Scenedesmus subspicatus. The maximum rate constant was 24.21 h-1 for the adsorption of Hg to Porphyridium purpureum whereas the maximum metal content (0.243 g g-1) was obtained for Zn on Cyclotella cryptica. A comparison of these values with those obtained for the mineral siliceous earth exhibiting low maximum content and high adsorption rates reveals that the mechanism of adsorption onto the algae is a mixture of adsorption and accumulation.     

CMOS blocks for on-chip RF test

In this paper we present two designs of CMOS blocks suitable for integration with RF frontend blocks for test purposes. Those are a programmable RF test attenuator and a reconfigurable low noise amplifier (LNA), optimized with respect to their function and location in the circuit. We discuss their performances in terms of the test- and normal operation mode. The presented application model aims at a transceiver under loopback test with enhanced controllability and detectability. The circuits are designed for 0.35μm CMOS process. Simulation results of the receiver frontend operating in 2.4 GHz band are presented showing tradeoffs between the performance and test functionality.     

Exact analytical theory of topology optimization with some pre-existing members or elements

This note deals with topological optimization of structures in which some members or elements of given cross-section exist prior to design and new members are to be added to the system. Existing members are costless, but new members and additions to the cross-section of existing members have a non-zero cost. The added weight is minimized for given behavioural constraints. The proposed analytical theory is illustrated with examples of least-weight (Michell) trusses having (a) stress or compliance constraints, (b) one loading condition and (c) some pre-existing members. Different permissible stresses in tension and compression are also considered. The proposed theory is also confirmed by finite element (FE)-based numerical solutions.     

Ligase detection reaction/hybridization assays using three-dimensional microfluidic networks for the detection of low-abundant DNA point mutations

We have fabricated a flow-through biochip assembly that consisted of two different microchips: (1) a polycarbonate (PC) chip for performing an allele-specific ligation detection reaction (LDR) and (2) a poly(methyl methacrylate) (PMMA) chip for the detection of the LDR products using an universal array platform. The operation of the device was demonstrated by detecting low-abundant DNA mutations in gene fragments (K-ras) that carry point mutations with high diagnostic value for colorectal cancers. The PC microchip was used for the LDR in a continuous-flow format, in which two primers (discriminating primer that carried the complement base to the mutation being interrogated and a common primer) that flanked the point mutation and were ligated only when the particular mutation was present in the genomic DNA. The miniaturized reactor architecture allowed enhanced reaction speed due to its high surface-to-volume ratio and efficient thermal management capabilities. A PMMA chip was employed as the microarray device, where zip code sequences (24-mers), which were complementary to sequences present on the target, were microprinted into fluidic channels embossed into the PMMA substrate. Microfluidic addressing of the array reduced the hybridization time significantly through enhanced mass transport to the surface-tethered zip code probes. The two microchips were assembled as a single integrated unit with a novel interconnect concept to produce the flow-through microfluidic biochip. A microgasket, fabricated from an elastomer poly(dimethylsiloxane) with a total volume of the interconnecting assembly of <200 nL, was used as the interconnect between the two chips to produce the three-dimensional microfluidic network. We successfully demonstrated the ability to detect one mutant DNA in 100 normal sequences with the biochip assembly. The LDR/hybridization assay using the assembly performed the entire assay at a relatively fast processing speed: 6.5 min for on-chip LDR, 10 min for washing, and 2.6 min for fluorescence scanning (total processing time 19.1 min) and could screen multiple mutations simultaneously.     

Forschungsperspektiven in der Energietechnik

6. Zusammenfassung  Effizienzsteigerungen und der übergang zu neuen Technologien in der Erzeugung und in der Endanwendung stellen Herausforderungen an die Energieforschung dar. Der übergang der Organisationsformen vom klassischen Energieversorger auf der Basis von Elektrizit?t zum Energiedienstleistungsunternehmen, das als Multi-Utility alle Arten der Versorgung und Endsorgung umfasst, ist vorgezeichnet. Die neue Energietechnik stellt Herausforderungen an die Forschung, um die langfristige Ressourcenbereitstellung, die Emissionsbegrenzungen, die Effizienzsteigerungen und die Automatisierung der Prozesse sicherzustellen. Kurzfassung eines Vortrags der 43. Fachtagung der ?sterreichischen Gesellschaft für Energietechnik (OGE) im OVE, die am 24. und 25. November 2005 in Innsbruck stattfindet.