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Independent Control (independent + control)
Selected AbstractsBiodegradable Polymer Crosslinker: Independent Control of Stiffness, Toughness, and Hydrogel Degradation RateADVANCED FUNCTIONAL MATERIALS, Issue 19 2009Chaenyung Cha Abstract Hydrogels are being increasingly studied for use in various biomedical applications including drug delivery and tissue engineering. The successful use of a hydrogel in these applications greatly relies on a refined control of the mechanical properties including stiffness, toughness, and the degradation rate. However, it is still challenging to control the hydrogel properties in an independent manner due to the interdependency between hydrogel properties. Here it is hypothesized that a biodegradable polymeric crosslinker would allow for decoupling of the dependency between the properties of various hydrogel materials. This hypothesis is examined using oxidized methacrylic alginate (OMA). The OMA is synthesized by partially oxidizing alginate to generate hydrolytically labile units and conjugating methacrylic groups. It is used to crosslink poly(ethylene glycol) methacrylate and poly(N -hydroxymethyl acrylamide) to form three-dimensional hydrogel systems. OMA significantly improves rigidity and toughness of both hydrogels as compared with a small molecule crosslinker, and also controls the degradation rate of hydrogels depending on the oxidation degree, without altering their initial mechanical properties. The protein-release rate from a hydrogel and subsequent angiogenesis in vivo are thus regulated with the chemical structure of OMA. Overall, the results of this study suggests that the use of OMA as a crosslinker will allow the implantation of a hydrogel in tissue subject to an external mechanical loading with a desired protein-release profile. The OMA synthesized in this study will be, therefore, highly useful to independently control the mechanical properties and degradation rate of a wide array of hydrogels. [source] Independent control of positive- and negative-sequence current components in a doubly fed machineEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 3 2005J. Bendl Abstract This paper analyses the operation of a power unit with a doubly fed machine. A novel vector control method is presented which enables independent control of both positive- and negative-sequence components of stator currents. Also, operation of the system under the condition of unbalanced voltage supply applied to the stator is discussed. Copyright © 2005 John Wiley & Sons, Ltd. [source] Functionalized, Swellable Hydrogel Layers as a Platform for Cell StudiesADVANCED FUNCTIONAL MATERIALS, Issue 8 2009Núria Marí-Buyé Abstract This paper reports the design, synthesis and characterization of thin films as a platform for studying the separate influences of physical and chemical cues of a matrix on the adhesion, growth and final phenotype of cells. Independent control of the physical and chemical properties of functionalized, swellable hydrogel thin films is achieved using initiated chemical vapor deposition (iCVD). The systematic variation in crosslink density is demonstrated to control the swelling ability of the iCVD hydrogel films based on 2-hydroxyethyl methacrylate (HEMA). At the same time, the incorporation of controllable concentrations of the active ester pentafluorophenyl methacrylate (PFM) allows easy immobilization of aminated bioactive motifs, such as bioactive peptides. Initial cell culture results with human umbilical vein endothelial cells (HUVEC) indicate that the strategy of using PFM to immobilize a cell-adhesion peptide motif onto the hydrogel layers promotes proper HUVEC growth and enhances their phenotype. [source] Experimental study of a doubly-fed rotary frequency converterELECTRICAL ENGINEERING IN JAPAN, Issue 4 2010Yasutoshi Takemoto Abstract Wind power generation using an unlimited, natural energy has been getting attention regarding environmental issues in recent years, and the installed capacity of wind power generation system is increasing at a rapid pace, resulting in deterioration of power quality especially in frequency and voltage. This fact will be a big problem in restricting large capacity of wind farms. This paper proposes a new frequency converter: rotary frequency converter (RFC) to moderate the electric output from wind generation, which is to be installed between a set of wind generators and a grid, providing a smoothed electric output, promoting the wind power generation introduction. This mainly consists of a synchronous machine and the adjustable-speed machine. Independent controls of input/output voltage, active power, and reactive power offer electrical separation between the two networks. Experimental study of a prototype model and its characteristics, especially dynamic control, is discussed in this paper. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 170(4): 26,34, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20922 [source] CEC-ESI ion trap MS of multiple drugs of abuseELECTROPHORESIS, Issue 7 2010Zeineb Aturki Abstract This article describes a method for the separation and determination of nine drugs of abuse in human urine, including amphetamines, cocaine, codeine, heroin and morphine. This method was based on SPE on a strong cation exchange cartridge followed by CEC-MS. The CEC experiments were performed in fused silica capillaries (100,,m×30,cm) packed with a 3,,m cyano derivatized silica stationary phase. A laboratory-made liquid junction interface was used for CEC-MS coupling. The outlet capillary column was connected with an emitter tip that was positioned in front of the MS orifice. A stable electrospray was produced at nanoliter per minute flow rates applying a hydrostatic pressure (few kPa) to the interface. The coupling of packed CEC columns with mass spectrometer as detector, using a liquid junction interface, provided several advantages such as better sensitivity, low dead volume and independent control of the conditions used for CEC separation and ESI analysis. For this purpose, preliminary experiments were carried out in CEC-UV to optimize the proper mobile phase for CEC analysis. Good separation efficiency was achieved for almost all compounds, using a mixture containing ACN and 25,mM ammonium formate buffer at pH 3 (30:70, v/v), as mobile phase and applying a voltage of 12,kV. ESI ion-trap MS detection was performed in the positive ionization mode. A spray liquid, composed by methanol,water (80:20, v/v) and 1% formic acid, was delivered at a nano-flow rate of ,200,nL/min. Under optimized CEC-ESI-MS conditions, separation of the investigated drugs was performed within 13,min. CEC-MS and CEC-MS2 spectra were obtained by providing the unambiguous confirmation of these drugs in urine samples. Method precision was determined with RSDs values ,3.3% for retention times and ,16.3% for peak areas in both intra-day and day-to-day experiments. LODs were established between 0.78 and 3.12,ng/mL for all compounds. Linearity was satisfactory in the concentration range of interest for all compounds (r2,0.995). The developed CEC-MS method was then applied to the analysis of drugs of abuse in spiked urine samples, obtaining recovery data in the range 80,95%. [source] Structural and functional differences between the promoters of independently expressed killer cell Ig-like receptorsEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 7 2005Bergen, Jeroen van Abstract Killer Ig-like receptors (KIR) are important for the recognition and elimination of diseased cells by human NK cells. Myeloid leukemia patients given a hematopoietic stem cell transplantation, for example, benefit from KIR-mediated NK alloreactivity directed against the leukemia cells. To establish an effective NK cell repertoire, most KIR genes are expressed stochastically, independently of the others. However, the sequences upstream of the coding regions of these KIR genes are highly homologous to the recently identified KIR3DL1 promoter (91.1,99.6% sequence identity), suggesting that they are regulated by similar if not identical mechanisms of transcriptional activation. We investigated the effects of small sequence differences between the KIR3DL1 promoter and other KIR promoters on transcription factor binding and promoter activity. Surprisingly, electrophoretic mobility shift assays and promoter-reporter assays revealed significant structural and functional differences in the cis-acting elements of these highly homologous KIR promoters, suggesting a key role for transcription factors in independent control of expression of specific KIR loci. Thus, the KIR repertoire may be shaped by a combination of both gene-specific and stochastic mechanisms. [source] Independent on-line control of the two hands during bimanual reachingEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2004Jörn Diedrichsen Abstract Many studies on bimanual coordination have shown that people exhibit a preference for mirror-symmetric movements. We demonstrate that this constraint is absent when bimanual reaching movements are made to visual targets. We investigated the ability of humans to make on-line adjustments during such movements when one or both targets were displaced during the initial phase of the movements. Adjustments were as efficient during bimanual as unimanual movements, even when two adjustments had to be made simultaneously. When one target was displaced in the bimanual condition, the hand reaching to that target adjusted efficiently to the displacement. However, a small transient perturbation in the trajectory of the other hand was also observed. This perturbation was in the same direction as the displacement, rather than in mirror-symmetric direction. A control experiment demonstrated that these perturbations could be elicited by visual information alone, but that they were also influenced by whether an adjustment was required in the trajectory of the other hand. Our results demonstrate near independent control of the two arms during visually guided reaching. The subtle interference observed between the arms reflects interactions between target-related representations in visual coordinates rather than between movement-related representations in joint- or muscle-coordinates. [source] Independent control of positive- and negative-sequence current components in a doubly fed machineEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 3 2005J. Bendl Abstract This paper analyses the operation of a power unit with a doubly fed machine. A novel vector control method is presented which enables independent control of both positive- and negative-sequence components of stator currents. Also, operation of the system under the condition of unbalanced voltage supply applied to the stator is discussed. Copyright © 2005 John Wiley & Sons, Ltd. [source] Programmable Drug Delivery: Core-Sheath Nanofibers Containing Colloidal Arrays in the Core for Programmable Multi-Agent Delivery (Adv. Mater.ADVANCED MATERIALS, Issue 9 20099/2009) Eun Chul Cho, Unyong Jeong, and co-workers demonstrate on p. 968 the programmable release of multiple agents by using polymeric core-sheath nanofibers consisting of arrays of colloids in the core and polymeric sheath. The fibers were produced by one-step single nozzle electrospinning. Loading different species of active agents in each colloid can provide independent control over the release of each agent. [source] CMOS digitally programmable quadrature oscillatorsINTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 8 2008Hussain A. Alzaher Abstract CMOS digitally programmable quadrature oscillators based on digitally controlled current followers and voltage followers are proposed. The proposed designs provide the advantage of programmability similar to the operational transconductance amplifier-based oscillators while offering improved linearity. In mixed analog/digital systems, the digital tuning feature allows direct interfacing with the digital signal processing part. Novel realizations that provide both voltage-mode and current-mode quadrature sinusoidal signals are presented. Employing only grounded capacitors the designs achieve independent control of the frequency and condition of oscillation that can be tuned digitally. Experimental results obtained from a 0.35,µm CMOS chip fabricated using standard CMOS process are given. Copyright © 2008 John Wiley & Sons, Ltd. [source] Experimental study on sulfur trioxide decomposition in a volumetric solar receiver,reactorINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 9 2009Adam Noglik Abstract Process conditions for the direct solar decomposition of sulfur trioxide have been investigated and optimized by using a receiver,reactor in a solar furnace. This decomposition reaction is a key step to couple concentrated solar radiation or solar high-temperature heat into promising sulfur-based thermochemical cycles for solar production of hydrogen from water. After proof-of-principle a modified design of the reactor was applied. A separated chamber for the evaporation of the sulfuric acid, which is the precursor of sulfur trioxide in the mentioned thermochemical cycles, a higher mass flow of reactants, an independent control and optimization of the decomposition reactor were possible. Higher mass flows of the reactants improve the reactor efficiency because energy losses are almost independent of the mass flow due to the predominant contribution of re-radiation losses. The influence of absorber temperature, mass flow, reactant initial concentration, acid concentration, and residence time on sulfur trioxide conversion and reactor efficiency has been investigated systematically. The experimental investigation was accompanied by energy balancing of the reactor for typical operational points. The absorber temperature turned out to be the most important parameter with respect to both conversion and efficiency. When the reactor was applied for solar sulfur trioxide decomposition only, reactor efficiencies of up to 40% were achieved at average absorber temperature well below 1000°C. High conversions almost up to the maximum achievable conversion determined by thermodynamic equilibrium were achieved. As the re-radiation of the absorber is the main contribution to energy losses of the reactor, a cavity design is predicted to be the preferable way to further raise the efficiency. Copyright © 2009 John Wiley & Sons, Ltd. [source] Modeling of partial oxidation in gas,solids downer reactorsAICHE JOURNAL, Issue 8 2010S. Vaishali Abstract Selective partial oxidations represent an important class of reactions in the process industry. Of particular interest is the partial oxidation of n-butane to maleic anhydride (MAN), which is arguably the largest commercialized alkane partial oxidation process. Partial oxidation of n-butane, which uses vanadium phosphorous oxide (VPO) as a heterogeneous catalyst, is believed to operate through a unique mechanism in which lattice oxygen oxidizes n-butane selectively to MAN. Past work has shown that performing partial oxidation reactions in gas,solids riser configuration is realizable and commercially viable, which has lead to commercialization of this technology in the last decade. Though the riser configuration allows optimal and independent control of the oxidation and reduction steps, the riser unit suffers from solid backmixing at walls, which in turn result into lower conversion, nonoptimal selectivity and diminished overall yield of desired product. In recent years, there has been growing interest in downers involving cocurrent downflow of both solids and gas phases, hence offering relatively uniform flow characteristics. In this contribution, we explore through modeling the implications of effecting partial oxidation reactions in a downer (gas,solids cocurrent downflow) compared to that in a conventional riser reactor (gas,solids cocurrent up flow) operated under equivalent operating conditions. Further, we explore the operational space of downers for these reactions, suggesting ways for improving the productivity of downer for partial oxidation applications. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] New MRI method with contrast based on the macromolecular characteristics of tissuesMAGNETIC RESONANCE IN MEDICINE, Issue 2 2003Arnon Neufeld Abstract A new MRI method with a contrast that is derived from the macromolecular composition and spin dynamics in the tissue is described and demonstrated on excised mouse brain and rat spinal cord. In the method, magnetization is selectively excited in the macromolecules by using a double quantum filter and subsequently transferred to water. The new imaging method differs from previous methods that rely on magnetization transfer contrast (MTC) in that it enables a separate and independent control of the effect of the macromolecule characteristics, chemical exchange, and water-related parameters on the images. Magn Reson Med 50:229,234, 2003. © 2003 Wiley-Liss, Inc. [source] Metamaterial transmission lines with tunable phase and characteristic impedance based on complementary split ring resonatorsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 8 2009Adolfo Vélez Abstract In this article, resonant-type tunable metamaterial transmission lines with independent control over the electrical parameters of the line, that is, the electrical length and characteristic impedance, are presented for the first time. Tuning is achieved by loading a host microstrip line with varactor-loaded complementary split ring resonators (VLCSRRs) and varactor diodes. By locating the varactor diodes in series configuration with the line, outside the region occupied by the VLCSRRs, it is possible to control the characteristic impedance and the electrical length (phase shift), over a wide band. As an illustrative example, a tunable 35 ,/90° line functional between 0.4 and 0.8 GHz (which represents more than 65% tuning range), is presented and applied to the design of a transmission line power divider. The device is small and it exhibits reasonable performance. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1966,1970, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24480 [source] Pharmacologic transgene control systems for gene therapyTHE JOURNAL OF GENE MEDICINE, Issue 5 2006Wilfried Weber Abstract Pharmacologic transgene-expression dosing is considered essential for future gene therapy scenarios. Genetic interventions require precise transcription or translation fine-tuning of therapeutic transgenes to enable their titration into the therapeutic window, to adapt them to daily changing dosing regimes of the patient, to integrate them seamlessly into the patient's transcriptome orchestra, and to terminate their expression after successful therapy. In recent years, decisive progress has been achieved in designing high-precision trigger-inducible mammalian transgene control modalities responsive to clinically licensed and inert heterologous molecules or to endogenous physiologic signals. Availability of a portfolio of compatible transcription control systems has enabled assembly of higher-order control circuitries providing simultaneous or independent control of several transgenes and the design of (semi-)synthetic gene networks, which emulate digital expression switches, regulatory transcription cascades, epigenetic expression imprinting, and cellular transcription memories. This review provides an overview of cutting-edge developments in transgene control systems, of the design of synthetic gene networks, and of the delivery of such systems for the prototype treatment of prominent human disease phenotypes. Copyright © 2006 John Wiley & Sons, Ltd. [source] Stabilization of an underactuated bottom-heavy airship via interconnection and damping assignmentINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 18 2007Zili Cai Abstract This paper focuses on feedback stabilization of a neutrally buoyant and bottom-heavy airship actuated by only five independent controls (with the rolling motion underactuated). The airship is modelled as an eudipleural submerged rigid body whose dynamics is formulated as a Hamiltonian system with respect to a Lie,Poisson structure. By exploiting the geometrical structure and using the so-called interconnection and damping assignment (IDA) passivity-based methodology for port-controlled Hamiltonian systems, state feedback control laws asymptotically stabilizing two typical motions are designed via La Salle invariance principle and Chetaev instability theorem. Simulation results verify the control laws. Copyright © 2007 John Wiley & Sons, Ltd. [source] Ancient DNA and Family Relationships in a Pompeian HouseANNALS OF HUMAN GENETICS, Issue 4 2009Giovanni Di Bernardo Summary Archaeological, anthropological and pathological data suggest that thirteen skeletons found in a house at the Pompeii archaeological site, dated to 79 A.D., belong to one family. To verify this and to identify the relationships between these individuals, we analyzed DNA extracted from bone specimens. Specifically, hypervariable segment 1 (HVS1) of the human mitochondrial DNA (mtDNA) control region was amplified in two overlapping polymerase chain reactions and the sequences were compared to the revised Cambridge Reference Sequence. As independent controls, other polymorphic sites in HVS1, HVS2 and in the coding region were analyzed. We also amplified some short tandem repeats of the thirteen specimens. This study revealed that six of the thirteen individuals are indeed closely related. [source] | |||||||||||||||||||