Parallel Adder Design with Reduced Circuit Complexity Using Resonant Tunneling Transistors and Threshold Logic

Quantum-effect devices utilizing resonant tunneling are promising candidates for future nano-scale integration. Originating from the technological progress of semiconductor technology, circuit architectures with reduced complexity are investigated by exploiting the negative-differential resistance of resonant tunneling devices. In this paper a resonant tunneling device threshold logic family based on the Monostable-Bistable Transition Logic Element (MOBILE) is proposed and applied to different parallel adder designs, such as ripple carry and binary carry lookahead adders. The basic device is a resonant tunneling transistor (RTT) composed of a resonant tunneling diode monolithically integrated on the drain contact layer of a heterostructure field effect transistor. On the circuit level the key components are a programmable NAND/NOR logic gate, threshold logic gates, and parallel counters. The special properties of MOBILE logic gates are considered by a bit-level pipelined circuit style. Experimental results are presented for the NAND/NOR logic gate.     

Improving surface quality in selective laser melting based tool making

In the last years, Additive Manufacturing, thanks to its capability of continuous improvements in performance and cost-efficiency, was able to partly replace and redefine well-established manufacturing processes. This research is based on the idea to achieve great cost and operational benefits especially in the field of tool making for injection molding by combining traditional and additive manufacturing in one process chain. Special attention is given to the surface quality in terms of surface roughness and its optimization directly in the Selective Laser Melting process. This article presents the possibility for a remelting process of the SLM parts as a way to optimize the surfaces of the produced parts. The influence of laser remelting on the surface roughness of the parts is analyzed while varying machine parameters like laser power and scan settings. Laser remelting with optimized parameter settings considerably improves the surface quality of SLM parts and is a great starting point for further post-processing techniques, which require a low initial value of surface roughness.

     

Mikrofiltration von Fermenterbrühen

Microfiltration of fermentation broths . Crossflow microfiltration is a modern process for the work-up of fermentation broths. In the case of intracellular components, the cells can be enriched by this technique prior to disintegration of the cells. Extracellular products can be separated from the cells by the microfiltration membrane, and also from solids originating from the nutrient. The approach adopted in isolation of dissolved products by crossflow microfiltration is illustrated for alkaline protease, particular attention being directed to the dependence of the flow of permeate and the retention of the membrane material, the mean pore size of the membrane, the operating conditions, the physical data of the fermentation broth, and the addition of solids, which are discussed and quantified.     

Drastic reduction of gate leakage in InAlAs/InGaAs HEMT's using apseudomorphic InAlAs hole barrier layer

Impact ionization in the channel of InAlAs/InGaAs HEMT's was shown to be a reason for excess gate leakage current. Hot electrons in the high field region of the channel under the gate generate electron-hole pairs. The generated holes can reach the gate (gate leakage) as well as the source, the electrons flow to the drain (kink effect). The number of holes reaching the gate strongly depends on the valence band discontinuity. In order to increase this valence band discontinuity a thin pseudomorphic InAlAs layer with high Al-content was inserted in the spacer of an InAlAs/InGaAs HEMT. The efficiency of this hole barrier was measured by photocurrent and DC measurements, while its influence on transport characteristics was measured by Hall and RF measurements. A reduction of gate leakage by a factor of 200 is demonstrated     

High fidelity transfer of nanometric random textures by UV embossing for thin film solar cells applications

We investigate the transfer of random nanostructures commonly used in thin film silicon solar cells onto inexpensive substrates, such as glass or flexible polyethylene sheets. Morphological and optical analyses of masters and replicas show the successful transfer of details with sizes much below 1 μm. These high-quality replicas are obtained by UV nano-imprinting, avoiding the use of PDMS as an intermediate mold, which has been identified as being responsible for the lack of resolution found in previous works.     

Nanogranular origins of the strength of bone

Here, we investigate the ultrastructural origins of the strength of bone, which is critical for proper physiological function. A combination of dual nanoindentation, three-dimensional elastic-plastic finite element analysis using a Mohr-Coulomb cohesive-frictional strength criterion, and angle of repose measurements was employed. Our results suggest that nanogranular friction between mineral particles is responsible for increased yield resistance in compression relative to tension and that cohesion originates from within the organic matrix itself, rather than organic-mineral bonding.     

Scalable Electrical Properties of Axial GaAs Nanowire <Emphasis Type="Italic">pn</Emphasis>-Diodes

In this letter the scalability of electrical properties of axial GaAs nanowire pn-diodes grown by Au-assisted metalorganic vapor-phase epitaxy is reported. The impact of the nanowire diameter on the forward current, the ideality factor, and the diode series resistance were investigated. Electrical measurements carried out on various single nanowires reveal the existence of a critical diameter for device functionality. Below that diameter the diode series resistance increases infinitely, which can be attributed to surface depletion. Above that diameter the forward current increases linearly with the junction area, while the series resistance demonstrates inverse proportionality. Hereby the ideality factor remains approximately constant at a value of 2. In addition, the analyzed axial GaAs nanowire pn-diodes offer very high rectification ratios ranging from 10⁴ to 10⁶ at ±2 V.     

Microporodynamics of Bones: Prediction of the “Frenkel–Biot” Slow Compressional Wave

Understanding of ultrasonic wave propagation in bones is essential for further development of related techniques in clinical practice. As any other saturated porous medium, bone is characterized by different forms of longitudinal wave propagation, either undrained waves or fast and (Frenkel–Biot) slow compressional waves. We here study the wave propagation in the framework of poromicromechanics. A continuum micromechanics model allows for the prediction of the anisotropic poroelastic properties, Biot’s coefficients, and moduli, from tissue-specific composition data, on the basis of tissue-independent (“universal”) elastic properties of the elementary components of all bones. These poroelastic properties enter the governing equations for wave propagation in anisotropic porous media. They allow for the prediction of undrained, fast and slow waves, as is verified by comparison of model results with experimental findings.     

Synthesis and Biological Evaluation of Pyrazoline and Pyrrolidine-2,5-dione Hybrids as Potential Antitumor Agents

In search of novel and effective antitumor agents, pyrazoline-substituted pyrrolidine-2,5-dione hybrids were designed, synthesized and evaluated in silico, in vitro and in vivo for anticancer efficacy. All the compounds exhibited remarkable cytotoxic effects in MCF7 and HT29 cells. The excellent antiproliferative activity toward MCF7 (IC₅₀=0.78±0.01 μM), HT29 (IC₅₀=0.92±0.15 μM) and K562 (IC₅₀=47.25±1.24 μM) cell lines, prompted us to further investigate the antitumor effects of the best compound S2 (1-(2-(3-(4-fluorophenyl)-5-(p-tolyl)-4,5-dihydro-1H-pyrazol-1-yl)-2-oxoethyl)pyrrolidine-2,5-dione). In cell-cycle analysis, S2 was found to disrupt the growth phases with increased cell population in G₁/G₀ phase and decreased cell population in G₂/M phase. The excellent in vitro effects were also supported by inhibition of anti-apoptotic protein Bcl-2. In vivo tumor regression studies of S2 in HT29 xenograft nude mice, exhibited equivalent and promising tumor regression with maximum TGI, 66 % (i. p. route) and 60 % (oral route) at 50 mg kg⁻¹ dose by both the routes, indicating oral bioavailability and antitumor efficacy. These findings advocate that hybridization of pyrazoline and pyrrolidine-2,5-dioes holds promise for the development of more potent and less toxic anticancer agents.     

Reaktionen beim Aufblasen von Kohlendioxid auf Fe-C-Cr-Schmelzen unter Vakuum

Abbrandverhalten der Begleitelemente. Entkohlungsgeschwindigkeit. Frischmittelausnutzung. Eindringtiefe eines Luftstrahls in Wasser. Chromverschlackung.