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Optimum Performance (optimum + performance)
Selected AbstractsEfficient low-power heteronuclear decoupling in 13C high-resolution solid-state NMR under fast magic angle spinningMAGNETIC RESONANCE IN CHEMISTRY, Issue S1 2007Mrignayani Kotecha Abstract The use of a low-power two-pulse phase modulation (TPPM) sequence is proposed for efficient 1H radio frequency (rf) decoupling in high-resolution 13C solid-state NMR (SSNMR) under fast MAS conditions. Decoupling efficiency for different low-power decoupling sequences such as continuous-wave (cw), TPPM, XiX, and ,-pulse (PIPS) train decoupling has been investigated at a spinning speed of 40 kHz for 13C CPMAS spectra of uniformly 13C - and 15N -labeled L -alanine. It was found that the TPPM decoupling sequence, which was originally designed for high-power decoupling, provides the best decoupling efficiency at low power among all the low-power decoupling sequences examined here. Optimum performance of the low-power TPPM sequence was found to be obtained at a decoupling field intensity (,1) of ,,R/4 with a pulse flip angle of ,, and a phase alternation between ± ,(, = ,20° ), where ,R/2, is the spinning speed. The sensitivity obtained for 13CO2,, 13CH, and 13CH3 in L -alanine under low-power TPPM at ,1/2, of 10 kHz was only 5,15% less than that under high-power TPPM at ,1/2, of 200 kHz, despite the fact that only 0.25% of the rf power was required in low-power TPPM. Analysis of the 13CH2 signals for uniformly 13C- and 15N-labeled L -isoleucine under various low-power decoupling sequences also confirmed superior performance of the low-power TPPM sequence, although the intensity obtained by low-power TPPM was 61% of that obtained by high-power TPPM. 13C CPMAS spectra of 13C -labeled ubiquitin micro crystals obtained by low-power TPPM demonstrates that the low-power TPPM sequence is a practical option that provides excellent resolution and sensitivity in 13C SSNMR for hydrated proteins. Copyright © 2007 John Wiley & Sons, Ltd. [source] Resource allocation with minimum rates for OFDM broadcast channels,EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 6 2007Carolin Huppert Downlink transmissions with minimum rate requirements over orthogonal frequency division multiplexing (OFDM) channels are commonly done by means of scheduling algorithms. However, regarding it from an information theoretical point of view, this is not optimal since broadcast techniques can achieve higher rates. The drawbacks of the optimum broadcast algorithm are that the signalling overhead is larger than for scheduling and also the computational complexity is much higher. In this paper we propose an algorithm which overcomes these points. This algorithm is a hybrid algorithm combining scheduling and broadcast approaches. Thus, it combines advantages of both methods. Furthermore, we present modifications to this algorithm to avoid irresolvable decoding dependencies. We show by means of simulation results that the proposed algorithm operates close to the optimum performance and that it outperforms a pure scheduling approach. Copyright © 2007 John Wiley & Sons, Ltd. [source] The Effect of Nanoparticle Shape on the Photocarrier Dynamics and Photovoltaic Device Performance of Poly(3-hexylthiophene):CdSe Nanoparticle Bulk Heterojunction Solar CellsADVANCED FUNCTIONAL MATERIALS, Issue 16 2010Smita Dayal Abstract The charge separation and transport dynamics in CdSe nanoparticle:poly(3-hexylthiophene) (P3HT) blends are reported as a function of the shape of the CdSe-nanoparticle electron acceptor (dot, rod, and tetrapod). For optimization of organic photovoltaic device performance it is crucial to understand the role of various nanostructures in the generation and transport of charge carriers. The sample processing conditions are carefully controlled to eliminate any processing-related effects on the carrier generation and on device performance with the aim of keeping the conjugated polymer phase constant and only varying the shape of the inorganic nanoparticle acceptor phase. The electrodeless, flash photolysis time-resolved microwave conductivity (FP-TRMC) technique is used and the results are compared to the efficiency of photovoltaic devices that incorporate the same active layer. It is observed that in nanorods and tetrapods blended with P3HT, the high aspect ratios provide a pathway for the electrons to move away from the dissociation site even in the absence of an applied electric field, resulting in enhanced carrier lifetimes that correlate to increased efficiencies in devices. The processing conditions that yield optimum performance in high aspect ratio CdSe nanoparticles blended with P3HT result in poorly performing quantum dot CdSe:P3HT devices, indicating that the latter devices are inherently limited by the absence of the dimensionality that allows for efficient, prolonged charge separation at the polymer:CdSe interface. [source] Nanobiomaterials and Nanoanalysis: Opportunities for Improving the Science to Benefit Biomedical Technologies,ADVANCED MATERIALS, Issue 5 2008W. Grainger Abstract Nanomaterials advocated for biomedical applications must exhibit well-controlled surface properties to achieve optimum performance in complex biological or physiological fluids. Dispersed materials with extremely high specific surface areas require as extensive characterization as their macroscale biomaterials analogues. However, current literature is replete with many examples of nanophase materials, most notably nanoparticles, with little emphasis placed on reporting rigorous surface analysis or characterization, or in formal implementation of surface property standards needed to validate structure-property relationships for biomedical applications. Correlations of nanophase surface properties with their stability, toxicity and biodistributions are essential for in vivo applications. Surface contamination is likely, given their processing conditions and interfacial energies. Leaching adventitious adsorbates from high surface area nanomaterials is a possible toxicity mechanism. Polydimethylsiloxane (PDMS), long known as a ubiquitous contaminant in clean room conditions, chemical synthesis and microfabrication, remains a likely culprit in nanosystems fabrication, especially in synthesis, soft lithography and contact molding methods. New standards and expectations for analyzing the interfacial properties of nanoparticles and nano-fabricated technologies are required. Surface science analytical rigor similar to that applied to biomedical devices, nanophases in microelectronics and heterogeneous catalysts should serve as a model for nanomaterials characterization in biomedical technologies. [source] Gain,bandwidth limitations of microwave transistorINTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 6 2002Filiz Güne Abstract This work enables one to obtain the potential gain (GT) characteristics with the associated source (ZS) and load (ZL) termination functions, depending upon the input mismatching (Vi), noise (F), and the device operation parameters, which are the configuration type (CT), bias conditions (VDS, IDS), and operation frequency (f). All these functions can straightforwardly provide the following main properties of the device for use in the design of microwave amplifiers with optimum performance: the extremum gain functions (GT max, GT min) and their associated ZS, ZL terminations for the Vi and F couple and the CT, VDS, IDS, and f operation parameters of the device point by point; all the compatible performance (F, voltage,standing wave ratio Vi, GT) triplets within the physical limits of the device, which are F , Fmin, Vi , 1, GT min , GT , GT max, together with their ZS, ZL termination functions; and the potential operation frequency bandwidth for a selected performance (F, Vi, GT) triplet. The selected performance triplet and termination functions can be realized together with their potential operation bandwidth using the novel amplifier design techniques. Many examples are presented for the potential gain characteristics of the chosen low-noise or ordinary types of transistor. © 2002 Wiley Periodicals, Inc. Int J RF and Microwave CAE 12, 483,495, 2002. Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mmce.10049 [source] Controlling western corn rootworm larvae with entomopathogenic nematodes: effect of application techniques on plant-scale efficacyJOURNAL OF APPLIED ENTOMOLOGY, Issue 5 2010S. Toepfer Abstract The three larval instars of western corn rootworm (Diabrotica virgifera virgifera LeConte, Coleoptera: Chrysomelidae) feed on the roots of maize, Zea mays (L.). The effects of six application techniques on the plant-scale efficacy of the entomopathogenic nematode species, Heterorhabditis bacteriophora Poinar (Rhabditida: Heterorhabditidae), in controlling D. v. virgifera populations were assessed in seven field plot experiments in southern Hungary between 2004 and 2007. Approximately 230 000 nematodes were applied per row metre using four different stream spray techniques; or, alternatively 400 000 nematodes per square metre using two different flat spray techniques. Nematode efficacy was assessed by comparing the number of emerging adult D. v. virgifera, and root damage between treatments and untreated controls. All tested nematode application techniques reduced D. v. virgifera density by at least 50% (on average across fields and years). The highest reduction in D. v. virgifera density was 68% and occurred when nematodes were applied into the soil together with maize sowing using a fluid solid stream. Rainfall, the day before application likely increased the control efficacy of H. bacteriophora. Using the 0.00,3.00 node injury damage rating scale, we estimated that potential root damage was prevented by 25,79% when H. bacteriophora was applied. Although, H. bacteriophora can effectively be applied with all of the techniques tested, for optimum performance and minimum costs, it is suggested that the nematodes be applied as follows: (i) as a stream requiring 8,10 times less volume of water than flat sprays, or as a granule requiring no water, and (ii) into the soil when sowing maize, requiring less water than soil surface sprays and avoiding the destruction of nematodes by UV radiation and additional machinery use. [source] Preparation of novel ZSM-5 zeolite-filled chitosan membranes for pervaporation separation of dimethyl carbonate/methanol mixturesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007Bingbing Liu Abstract Novel mixed matrix membranes were prepared by incorporating ZSM-5 zeolite into chitosan polymer for the pervaporative separation of dimethyl carbonate (DMC) from methanol. These membranes were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) to assess their morphology, intermolecular interactions, and crystallinity. Sorption studies indicated that the degree of swelling for zeolite-filled membranes increased with zeolite content in the membrane increasing and the separation selectivity of DMC/methanol was dominated by solubility selectivity rather than diffusivity selectivity. The characteristics of these membranes for separating DMC/methanol mixtures were investigated by varying zeolite content, feed composition, and operating temperature. The pervaporation separation index (PSI) showed that 5 wt % of ZSM-5 zeolite-filled membrane gave the optimum performance in the PV process. From the temperature-dependent permeation values, the Arrhenius activation parameters were estimated. The resulting lower activation energy values obtained for zeolite-filled membranes contribute to the framework of the zeolite. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source] Investigation of top gate electrode options for high-k gate dielectric MOS capacitorsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2008D. C. Moschou Abstract Capacitors with a high-k HfO2 film as gate dielectric were fabricated, using three different variations for the top gate electrode. This way it was possible to acquire important information on which kind of gate material should be used in combination with HfO2 as a gate insulator for optimum performance of possible low temperature applications, such as high-k TFTs. The variations of gate electrode were e-gun evaporated Al, sputtered W and CVD polysilicon followed by ion implantation and annealing. The capacitors were then characterized with capacitance-voltage measurements and current-voltage measurements. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Measurement of inhibin A: a modification to an enzyme-linked immunosorbent assayPRENATAL DIAGNOSIS, Issue 8 2001Prema P. Thirunavukarasu Abstract Inhibin A is a useful prenatal marker of Down syndrome. Currently, the available enzyme-linked immunosorbent assays (ELISAs) for inhibin A are based upon the same paired monoclonal antibodies. In the present study we have confirmed for one of those ELISAs that short-term sample storage as whole blood leads to a significant decline in detectable inhibin A and that this is most likely due to erythrocyte catalase interference with a critical oxidation step in the assay. While this interference can be eliminated by heating the samples pre-assay, this process is labour intensive. In the present study we have demonstrated that the addition of 3-amino-1,2,4-triazole (AT), a catalase ,suicide' inhibitor, also prevents the decline of inhibin A levels in samples stored as whole blood. We suggest that the addition of AT to samples prior to assay is a simple modification to the inhibin A ELISA that affords optimum performance. Copyright © 2001 John Wiley & Sons, Ltd. [source] An optimum method designed for 2-D DIGE analysis of human arterial intima and media layers isolated by laser microdissectionPROTEOMICS - CLINICAL APPLICATIONS, Issue 10 2009Fernando de la Cuesta Abstract The formation and progression of atherosclerotic lesions involve complex mechanisms which are still not fully understood. A variety of cell types from the distinct arterial layers are implicated in the whole process from lipid accumulation within the vascular wall to plaque development and final rupture. In the present work, we employ the combination of laser microdissection and pressure catapulting and 2-D DIGE saturation labeling to investigate the human intima and media sub-proteomes isolated from atherosclerotic (coronary and aorta) or non-atherosclerotic vessels (preatherosclerotic coronary arteries). Laser microdissection and pressure catapulting allows the specific isolation of regions of interest. In turn, DIGE saturation labeling overcomes the limitation of extensive microdissection times to recover the protein amount required to perform comparative 2-DE, particularly when dealing with tissue regions rich in myofilament proteins, which result in low protein recovery. The compatibility and optimum performance of both techniques were investigated in detail, paying special attention to tissue staining and protein solubilization. Since scarce amount of protein obtained from microdissected tissue made it impossible to directly perform protein identification from 2-DE spots by MS, we performed in-solution digestion followed by LC-MS/MS analysis of total protein extracts from intima and media in order to get an overall picture of protein composition. Proteins so identified confirm the nature of the isolated regions. Finally, similar spot resolution on 2-D DIGE gels was obtained for the different human artery types (coronary, aorta) and studied layers (intima, media), setting the basis for future clinical comparative studies. [source] Effects of varying dietary compositions using common feed ingredients on growth and feed efficiency of pond-raised channel catfish Ictalurus punctatus (Rafinesque)AQUACULTURE RESEARCH, Issue 8 2010Menghe H Li Abstract Two experiments were conducted to evaluate various ingredient combinations in a 28% or 32% protein diet for optimum performance of channel catfish Ictalurus punctatus. All diets contained soybean meal and corn, but with or without cottonseed meal, wheat middlings or fish meal (FM). Channel catfish fingerlings were stocked into 0.04 ha earthen ponds at 18 530 fish ha,1. Fish were fed one of eight diets once daily to apparent satiation for two growing seasons. Results demonstrated that the dietary ingredient composition used had significant effects on fish performance, but magnitude of differences was relatively small. Overall, diets containing FM resulted in greater weight gain (Experiments 1 and 2) and lower feed conversion ratio (Experiment 1) than fish fed all-plant diets. However, certain combinations of plant ingredients provided the similar fish growth as some diets containing FM. There were no significant differences in weight gain between fish fed soybean meal,corn or soybean meal,corn,wheat middlings-based diets with cottonseed meal or FM. The use of wheat middlings in the diet had no significant effects on fish production characteristics. [source] Impact of digestible energy levels at three different dietary amino acid levels on growth performance and protein accretion in Atlantic salmonAQUACULTURE RESEARCH, Issue 3 2010Adel El-Mowafi Abstract Nine experimental feeds were prepared, having two different digestible energy levels (DE, 19.5 and 21.5 MJ kg,1) and three different amino acid levels (90%, 100% and 110%), and formulated with two alternative strategies (protein and fat vary freely or only protein varies freely). The design was not balanced and thus the 110% amino acid profile was only studied at 19.5 MJ kg,1 DE. Atlantic salmon (Salmo salar) with a mean body weight of 449±19 g were distributed in 24 tanks and were fed each of the experimental diets for a period of 90 days. The fish were fed three times daily and uneaten feed was collected. Increasing the dietary DE energy from 19.5 to 21.5 MJ kg,1 and the amino acid level from 90% to 100% of the requirement increased the feed intake and growth performance in Atlantic salmon. Increasing the amino acid level from 90% to 100% had a positive effect on the feed intake, growth and protein accretion. Also, the mRNA levels of insulin-like growth factor I in muscle tissues pointed to this positive effect when the amino acid level increased. High probabilities were associated with a negative effect on the feed intake of reducing the amino acid level regardless of the DE level. It is recommended that the balanced amino acid level should not be adjusted by the same percentage rate as dietary energy, and possibly should not be reduced at all in order to maintain optimum performance and profitability. [source] An optimal maintenance policy based on generalized stochastic Petri nets and periodic inspectionASIAN JOURNAL OF CONTROL, Issue 3 2010Ching-Kao Chang Abstract Periodic maintenance of equipment is essential for its optimum performance, thereby enabling production efficiency. In the past, studies on preventive maintenance of automated manufacturing systems (AMS) determined the optimal preventive maintenance policy under different performance indexes. Generally, most hypotheses indicate that equipment reliability can be restored to 1.0 through preventive and corrective maintenance. However, in practical application, the implementation of preventive maintenance results in partial deterioration of equipment; moreover, the reliability of equipment cannot be restored to as-good-as-new. In addition, the greater the complexity of connections of the equipment, the greater is the difficulty in determining the timing for preventive maintenance. On account of these characteristics, generalized stochastic Petri nets (GSPN) are well-suited for the implementation of preventive maintenance. Therefore, this paper applies GSPN for deciding the optimal maintenance policy and constructing models for different levels of maintenance and renewal for an AMS with a serial-parallel layout. As a result of the application of GSPN, the following optimal maintenance policy for an AMS was obtained in this study: Preventive maintenance conducted at intervals of every 240 hours will reduce cost by 46% as opposed to the practice of replacing defective parts when necessary. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source] | ||||||||||||||||