A room temperature 0.1 μm CMOS on SOI

An advanced 0.1 μm CMOS technology on SOI is presented. In order to minimize short channel effects, relatively thick nondepleted (0.15 μm) SOI film, highly nonuniform channel doping and source-drain extension-halo were used. Excellent short channel effects (SCE) down to channel lengths below 0.1 μm were obtained. It is shown that undepleted SOI results in better short channel effect when compared to ultrathin depleted SOI. Devices with little short channel effect all the way to below 500 Å effective channel length were obtained. Furthermore, utilization of source-drain extension-halo minimizes the bipolar effect inherent in the floating body. These devices were applied to a variety of circuits: Very high speeds were obtained: Unloaded delay was 20 ps, unloaded NAND (FI=FO=3) was 64 ps, and loaded NAND (FI=FO=3, C_L=0.3 pF) delay was 130 ps at supply of 1.8 V. This technology was applied to a self-resetting 512 K SRAM. Access times of 2.5 ns at 1.5 V and 3.5 ns at 1.0 V were obtained     

Semiconductor surface studies with SAW-oscillator structures

A new method is described whereby the surface charge against surface potential of an oxidised semiconductor sample can be obtained by measuring the frequency shift of a SAW delay-line oscillator. In this method a direct voltage is applied across the semiconductor with different configurations. The SAW delay line is made on LiNbO3 and is designed to oscillate (at 100 MHz) with a wideband amplifier in a feedback configuration.     

High-performance devices for a 0.15-μm CMOS technology

Devices have been designed and fabricated in a CMOS technology with a nominal channel length of 0.15 μm and minimum channel length below 0.1 μm. In order to minimize short-channel effects (SCEs) down to channel lengths below 0.1 μm, highly nonuniform channel dopings (obtained by indium and antimony channel implants) and shallow source-drain extensions/halo (by In and Sb preamorphization and low-energy As and BF₂ implant were used. Maximum high V _DS threshold rolloff was 250 mV at effective channel length of 0.06 μm. For the minimum channel length of 0.1 μm, the loaded (FI=FO=3, C=240 fF) and unloaded delays were 150 and 25 ps, respectively     

Existence of solutions for a class of nonlinear Volterra singular integral equations

In this paper we prove some results concerning the existence of solutions for a large class of nonlinear Volterra singular integral equations in the space C[0,1] consisting of real functions defined and continuous on the interval [0,1]. The main tool used in the proof is the concept of a measure of noncompactness. We also present some examples of nonlinear singular integral equations of Volterra type to show the efficiency of our results. Moreover, we compare our theory with the approach depending on the use of the theory of Volterra-Stieltjes integral equations. We also show that the results of the paper are applicable in the study of the so-called fractional integral equations which are recently intensively investigated and find numerous applications in describing some real world problems.     

Liquid–liquid extraction of toluene from its mixtures with aliphatic hydrocarbons using an ionic liquid as the solvent

The knowledge of liquid–liquid equilibria (LLE) of the ternary systems (alkane/toluene/ionic liquid) is essential to develop thermodynamic models for liquid–liquid extraction of aromatics such as toluene from its mixtures with aliphatic hydrocarbons. In this study, new experimental LLE data for the ternary systems (hexane and heptane/toluene/1-methyl-3-octylimidazolium tetraflouroborate) are measured at T = 298.15 K and atmospheric pressure. The capability of ionic liquid for extracting toluene from its azeotropic mixture with aliphatic hydrocarbons (hexane and heptane) has been evaluated by the selectivity and solute distribution coefficients. The Othmer–Tobias equation has been applied to check the consistency of the experimental tie-lines. Finally, the obtained experimental LLE data are satisfactorily correlated by the nonrandom two-liquid model.     

Directed Evolution of Hyaluronic Acid Synthase from Pasteurella multocida towards High‐Molecular‐Weight Hyaluronic Acid

Hyaluronic acid (HA), with diverse cosmetic and medical applications, is the natural glycosaminoglycan product of HA synthases. Although process and/or metabolic engineering are used for industrial HA production, the potential of protein engineering has barely been realised. Herein, knowledge‐gaining directed evolution (KnowVolution) was employed to generate an HA synthase variant from Pasteurella multocida (pmHAS) with improved chain‐length specificity and a twofold increase in mass‐based turnover number. Seven improved pmHAS variants out of 1392 generated by error‐prone PCR were identified; eight prospective positions were saturated and the most beneficial amino acid substitutions were recombined. After one round of KnowVolution, the longest HA polymer (<4.7 MDa), through an engineered pmHAS variant in a cell‐free system, was synthesised. Computational studies showed that substitutions from the best variant (T40L, V59M and T104A) are distant from the glycosyltransferase sites and increase the flexibility of the N‐terminal region of pmHAS. Taken together, these findings suggest that the N terminus may be involved in HA synthesis and demonstrate the potential of protein engineering towards improved HA synthase activity.     

High performance implementation of texture features extraction algorithms using FPGA architecture

The most popular second-order statistical texture features are derived from the co-occurrence matrix, which has been proposed by Haralick. However, the computation of both matrix and extracting texture features are very time consuming. In order to improve the performance of co-occurrence matrices and texture feature extraction algorithms, we propose an architecture on FPGA platform. In the proposed architecture, first, the co-occurrence matrix is computed then all thirteen texture features are calculated in parallel using computed co-occurrence matrix. We have implemented the proposed architecture on Virtex 5 fx130T-3 FPGA device. Our experimental results show that a speedup of 421[× yields over a software implementation on Intel Core i7 2.0 GHz processor. In order to improve much more performance on textures, we have reduced the computation of 13 texture features to 3 texture features using ranking of Haralick’s features. The performance improvement is 484×.     

Three-segment variable structure systems

The theory of variable structure systems is extended to three-segment variable structure systems. This is an effective means to insensitize a system to parameter variations and disturbances. The sliding mode region is extended and the response can start and stay on the sliding mode from the initial to final running time. Examples are given to illustrate the effectiveness of the proposed method. The simulation results show the superiority of the three-segment variable structure systems.     

Hijacking Chemical Reactions of P450 Enzymes for Altered Chemical Reactions and Asymmetric Synthesis

Cytochrome P450s are heme-containing enzymes capable of the oxidative transformation of a wide range of organic substrates. A protein scaffold that coordinates the heme iron, and the catalytic pocket residues, together, determine the reaction selectivity and regio- and stereo-selectivity of the P450 enzymes. Different substrates also affect the properties of P450s by binding to its catalytic pocket. Modulating the redox potential of the heme by substituting iron-coordinating residues changes the chemical reaction, the type of cofactor requirement, and the stereoselectivity of P450s. Around hundreds of P450s are experimentally characterized, therefore, a mechanistic understanding of the factors affecting their catalysis is increasingly vital in the age of synthetic biology and biotechnology. Engineering P450s can enable them to catalyze a variety of chemical reactions viz. oxygenation, peroxygenation, cyclopropanation, epoxidation, nitration, etc., to synthesize high-value chiral organic molecules with exceptionally high stereo- and regioselectivity and catalytic efficiency. This review will focus on recent studies of the mechanistic understandings of the modulation of heme redox potential in the engineered P450 variants, and the effect of small decoy molecules, dual function small molecules, and substrate mimetics on the type of chemical reaction and the catalytic cycle of the P450 enzymes.     

Investigating Pulsed Discharge Polarity Employing Solid-state Pulsed Power Electronics

The power electronics technique has become a key technology in solid-state pulsed power supplies. Since pulsed power applications have been matured and found their way into many industrial applications, moving toward energy efficiency is gaining much more interest. Therefore, finding an optimum operation condition plays an important role in maintaining the desired performance. Investigating the system parameters contributed to the generated pulses is an effective way in improving the system performance further ahead. One of these parameters is discharge polarity, which has received less attention. In this article, the effects of applied voltage polarity on plasma discharge have been investigated in different mediums at atmospheric pressure. The experiments have been conducted based on a high-voltage DC power supply and a high-voltage pulse generator for point-to-point and point-to-plane geometries. Furthermore, the influence of electric field distribution is analyzed using finite-element simulations for the employed geometries and mediums. The experimental and simulation results have verified the important role of the applied voltage polarity, employed geometry, and medium of the system on plasma generation.