Synthesis of thermoset plastics by Lewis acid initiated copolymerization of fish oil ethyl esters and alkenes

The Lewis acid initiated cationic homopolymerization of Norway fish oil ethyl ester (NFO) or the corresponding conjugated fish oil (CFO) and their copolymerization with various alkene comonomers is investigated. Among the Lewis acids employed, boron trifluoride diethyl etherate (BFE, BF₃ · OEt₂) is found to be the most effective initiator for cationic polymerization of the NFO and CFO systems. The BFE‐initiated homopolymerization of NFO generally results in low molecular weight viscous oils, while that of CFO leads to a solid elastic gel with a gel time of more than 72 h at room temperature. Copolymerization of the NFO or CFO with some alkene comonomers significantly facilitates gelation. The gel times are largely dependent upon the stoichiometry, the type of fish oil, and the alkene comonomer. After postcuring at elevated temperatures, the cationic copolymerization affords polymers ranging from soft rubbery materials to rigid plastics. These NFO and CFO polymers are composed of highly crosslinked materials and a certain amount of free oils and are found to be fully cured thermosets. Generally, CFO polymers appear to be harder than the corresponding NFO polymers. However, the thermal properties of the bulk polymers are similar to each other, and their insoluble extracts exhibit much higher thermal stability than the bulk thermosets. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2001–2012, 2001     

A 90-nm CMOS Low-Power GSM/EDGE Multimedia-Enhanced Baseband Processor With 380-MHz ARM926 Core and Mixed-Signal Extensions

To meet the widely varying speed and power requirements of multifunctional mobile devices, an appropriate combination of technology features, circuit-level low-power techniques, and system architecture is implemented in a GSM/Edge baseband processor with multimedia and mixed-signal extensions. Power reduction techniques and performance requirements are derived from an analysis of relevant use cases and applications. The 44 mm² baseband processor is fabricated in a 90-nm low-power CMOS technology with triple-well option and dual-gate oxide core devices. The ARM926 core achieves a maximum clock frequency of 380 MHz at 1.4-V supply due to the usage of thin oxide (1.6 nm) devices. Power dissipation can be adapted to the performance requirements by means of combined voltage and frequency scaling to reduce active power consumption in medium-performance mode by 68%. To reduce leakage currents during standby mode, large SRAM blocks, nFET sleep transistors, and circuit components with relaxed performance requirements are implemented using devices with 2.2-nm gate oxide thickness     

Guidewire knot formation during insertion of a central venous catheter

A knot was formed on the guidewire during the procedure of inserting a central venous catheter through the right subclavian vein. The diameter of the knot was 3 mm after it had been pulled as tight as possible. Fortunately, there was no sign of severe haemothorax, though the knot must have caused considerable damage to the vessel.     

Molecular diversity of Staphylococcus aureus and the role of milking equipment adherences or biofilm as a source for bulk tank milk contamination

Staphylococcus aureus is one of the most frequent pathogens causing intramammary infections in dairy herds. Consequently, virulence factors, pathobiology, and epidemiology of Staphylococcus aureus strains have been widely assessed through the years. Nevertheless, not much has been described about the epidemiology of Staph. aureus strains from bulk tank milk (BTM) and adherences on milking equipment (AMES), even when these strains may play a role in the quality of milk that is intended for human consumption. The objective of this study was to assess the strain diversity of 166 Staph. aureus isolates collected from 3 consecutive BTM samples, and from AMES in contact with milk from 23 Chilean dairy farms. Isolates were analyzed and typed using pulsed-field gel electrophoresis. Diversity of strains, both within and among farms, was assessed using Simpson's index of diversity (SID). On farms where Staph. aureus was isolated from both AMES and BTM (n = 8), pulsotypes were further analyzed to evaluate the role of AMES as a potential source of Staph. aureus strains in BTM. Among all Staph. aureus analyzed by pulsed-field gel electrophoresis, a total of 42 pulsotypes (19 main pulsotypes and 23 subtypes) were identified. Among dairy farms, strain diversity was highly heterogeneous (SID = 0.99). Within dairy farms, Staph. aureus strain diversity was variable (SID = 0 to 1), and 18 dairy operations (81.8%) had one pulsotype that was shared between at least 2 successive BTM samples. In those farms where Staph. aureus was isolated in both AMES and BTM (n = 8), 7 (87.5%) showed a clonal distribution of Staph. aureus strains between these 2 types of samples. The overlapping of certain Staph. aureus strains among dairy farms may point out common sources of Staph. aureus among otherwise epidemiologically unrelated farms. Indistinguishable Staph. aureus strains between AMES and BTM across dairy farms suggest that Staph. aureus–containing AMES may represent a source for BTM contamination, thus affecting milk quality. Our study highlights the role of viable Staph. aureus in AMES as a source for BTM contamination on dairy farms, and also describes the overlapping and presence of specific BTM and AMES pulsotypes among farms.     

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.     

Aspects of systems and circuits for nanoelectronics

A large number of devices, a limitation of wiring, and very low power dissipation density are design constraints of future nanoelectronic circuits composed of quantum-effect devices. Furthermore, functional integration, which is the possibility of exploiting quantum effects to obtain a function specific behavior, becomes a core design principle. This paper analyzes the effect of this technological progress on the design of nanoelectronic circuits and describes computational paradigms revealing novel features such as distributed storage, fault tolerance, self-organization, and local processing. In particular, linear threshold networks, the associative matrix, self-organizing feature maps, and cellular arrays are investigated from the viewpoint of their potential significance for nanoelectronics. Although these concepts have already been implemented using present technologies, the intention of this paper is to give an impression of their usefulness to system implementations with quantum-effect devices     

Efficiency of body biasing in 90-nm CMOS for low-power digital circuits

The efficiency of body biasing for leakage reduction and performance improvement in a 90-nm CMOS low-power technology with triple-well option is evaluated. Static measurements of single devices and dynamic measurements of ring oscillators and 32-b parallel prefix adders are presented. Whereas forward biasing still provides a significant performance improvement of up to 37% for low-leakage devices with 2.2-nm gate oxide thickness, the application of reverse biasing to reduce subthreshold leakage currents is inefficient due to additional leakage currents such as gate leakage and gate-induced drain leakage. Experimental results confirm that, in 90-nm CMOS circuits, the efficiency of body biasing strongly depends on the device type and operating temperature. Moreover, the impact of the zero-temperature coefficient point on static device and dynamic circuit performance is investigated.     

Determination of SDZ ICM 567 in blood and muscle microdialysis samples by microbore liquid chromatography with ultraviolet and fluorescence detection

Fast, simple and accurate methods for the determination of SDZ ICM 567, the 7-methoxy derivative of tropisetron, in microdialysates have been developed. Sampling by microdialysis from freely moving rats in the portal and jugular vein offers a new technology for pharmacokinetic studies by direct and continuous measurement of unbound drug concentrations with time. SDZ ICM 567 can be identified in small sample volumes of dialysates on a microbore high-performance liquid chromatography column-switching system with ultraviolet detection. In addition, determination of SDZ ICM 567 by fluorimetric detection has been developed for muscle microdialysates from rats. [14C]SDZ ICM 567 was used as reference substance for the estimation of the amount of substance transferred through the dialysis membrane. The radioactive measurement (RA) gave the recovery information, whereas the liquid chromatographic method detected the sum of [14C]SDZ ICM 567 and dialyzed SDZ ICM 567.     

Dynamic state-retention flip-flop for fine-grained power gating with small design and power overhead

Fine-grained power gating is the rigorous application of sleep transistor scheme to reduce stand-by power consumption in idle circuit blocks. Small circuit blocks are suspended for a short time while they are temporarily not needed. A sense-amplifier-based state retention flip-flop is proposed, that preserves the logical state of the circuit during these short idle periods. This dynamic state retention flip-flop requires neither additional control signals nor an additional power supply for its state retention functionality. An integration into a standard design flow is possible without any modifications. The tradeoff between propagation delay and retention time is derived analytically. Retention times in the range of milliseconds can be achieved with D-to-Q delays of 100 ps to 200 ps.     

Threshold logic circuit design of parallel adders using resonanttunneling devices

Resonant tunneling devices and circuit architectures based on monostable-bistable transition logic elements (MOBILEs) are promising candidates for future nanoscale integration. In this paper, the design of clocked MOBILE-type threshold logic gates and their application to arithmetic circuit components is investigated. The gates are composed of monolithically integrated resonant tunneling diodes and heterostructure field-effect transistors. Experimental results are presented for a programmable NAND/NOR gate. Design related aspects such as the impact of lateral device scaling on the circuit performance and a bit-level pipelined operation using a four phase clocking scheme are discussed. The increased computational functionality of threshold logic gates is exploited in two full adder designs having a minimal logic depth of two circuit stages. Due to the self-latching behavior the adder designs are ideally suited for an application in a bit-level pipelined ripple carry adder. To improve the speed a novel pipelined carry lookahead addition scheme for this logic family is proposed