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Controllable
Terms modified by Controllable Selected AbstractsSYSTEMS WITH NONEQUIDISTANT SAMPLING: CONTROLLABLE?ASIAN JOURNAL OF CONTROL, Issue 4 2005OBSERVABLE? ABSTRACT Some qualitative properties of systems with nonequidistant sampling are investigated. First, it is proved that the nonequidistant sampling pattern mentioned in [1] does not affect the controllability and observability of time-varying linear systems during discretization. The result is claimed to be true for linear systems with periodic behavior and time-varying sampling. Second, closed-loop stability conditions are established, respectively, for linear and nonlinear sampled-data systems consisting of continuous plants and linear digital feedback controllers. The stability results are extended to general systems consisting of nonlinear continuous plants and nonlinear digital controllers with time-varying sampling periods. [source] Interpenetrating Polymer Networks with Spatially Graded Morphology Controllable by UV-Radiation CuringMACROMOLECULAR SYMPOSIA, Issue 1 2006Hideyuki Nakanishi Abstract Interpenetrating Polymer Networks (IPNs) composed of polystyrene (PS) and poly(methyl methacrylate) (PMMA) were synthesized from a precursor mixture by using dissimilar photo-cross-link reactions. When the reation yields exceeded a certain threshold, the mixture was quenched from one-phase region into two-phase region, leading to phase separation. Upon irradiation with strong UV-light, an intensity gradient was formed along the propagating direction of the exciting light, generating a gradient of quench depth via the spatial inhomogeneity of the cross-link reactions. As a consequence, a gradient of the characteristic length scales was continuously generated from the top to the bottom of the mixture. The resulting three-dimensional (3-D) morphology was in-situ observed at different depths of the mixture by using a laser-scanning confocal microscope (LSCM). From this 3-D observation, it was found that phase separation was accelerated at the bottom of the mixture and proceeded in an autocatalytic fashion. The mechanism for the formation of the graded morphology was discussed in conjunction with the kinetics of the autocatalytic phase separation. [source] Retraction: Controllable Fabricate Intrinsic Fluorescent Polymer Nanoparticles Array by Atmospheric Pressure Plasma PolymerizationPLASMA PROCESSES AND POLYMERS, Issue 2 2010Ping Yang This article has been retracted: Controllable Fabricate Intrinsic Fluorescent Polymer Nanoparticles Array by Atmospheric Pressure Plasma Polymerization (Plasma Process. Polym. 2009, DOI: 10.1002/ppap.200950007) [source] A new family of generalized-, time integration algorithms without overshoot for structural dynamicsEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 12 2008Yu KaiPing Abstract A new family of generalized-, (G-,) algorithm without overshoot is presented by introducing seven free parameters into the single-step three-stage formulation for solution of structural dynamic problems. It is proved through finite difference analysis that these algorithms are unconditionally stable, second-order accurate and numerical dissipation controllable. The comparison of the new G-, algorithms with the commonly used G-, algorithms shows that the newly developed algorithms have the advantage of eliminating the overshooting characteristics exhibited by the commonly used algorithms while their excellent property of dissipation is preserved. The numerical simulation results obtained using a single-degree-of-freedom system and a two-degree-of-freedom system to represent the character of typical large systems coincide well with the results of theoretical analyses. Copyright © 2008 John Wiley & Sons, Ltd. [source] Spherical sliding isolation bearings with adaptive behavior: Experimental verificationEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 2 2008Daniel M. Fenz Abstract This paper describes an experimental program to examine the force,displacement behavior of a class of multi-spherical sliding bearings. The primary goal of the experiments is to test the validity of the theory developed in a companion paper that describes the behavior of these devices. Experimental work consisted of testing the three primary variations of these bearings in several configurations of different friction and displacement capacities. Most tests were carried out at slow speeds; however, some testing was also conducted at high speed (up to approximately 400,mm/s) to examine the behavior under dynamic conditions. The results of experimental testing were generally found to be in very good agreement with the analytical results. It is shown that the forces and displacements at which transitions in stiffness occur are predictable and therefore controllable in design. Furthermore, the underlying principles of operation were confirmed by the fact that starting and stopping of sliding on the different surfaces occurred as expected from theory. Copyright © 2007 John Wiley & Sons, Ltd. [source] Nano vanadyl-phthalocyanine crystals fabricated on KBr substrateELECTRICAL ENGINEERING IN JAPAN, Issue 2 2008Suguru Mototani Abstract Vanadyl-phthalocyanine (VOPc) thin films deposited on a KBr substrate by molecular beam epitaxy (MBE) consist of nano-VOPc crystals epitaxially grown. The nano-VOPc crystals acquire a square shape as a result of annealing at 150°C. The size of the nano-crystals is controllable by changing the conditions of MBE deposition and thermal treatment. The growth processes of nano-crystals on the KBr substrate are elucidated experimentally and are shown to be closely related to strong interaction between the VOPc molecules and the KBr substrate. Their mechanisms can be explained in terms of surface diffusion of the VOPc molecules on the KBr substrate. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 163(2): 41,48, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20645 [source] Dissociable neural activity to self- vs. externally administered thermal hyperalgesia: a parametric fMRI studyEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2008C. Mohr Abstract Little is known regarding how cognitive strategies help to modulate neural responses of the human brain in ongoing pain syndromes to alleviate pain. Under pathological pain conditions, any self-elicited contact with usually non-painful stimuli may become painful. We examined whether the human brain is capable of dissociating self-controlled from externally administered thermal hyperalgesia in the experimental capsaicin model. Using functional magnetic resonance imaging, 17 male subjects were investigated in a parametric design with heat stimuli at topically capsaicin-sensitized skin. In contrast to external stimulation, self-administered pain was controllable. For both conditions application trials without noticeable thermal stimulation were introduced and used as high-level baseline (HLB) to account for the capsaicin-induced ongoing pain and other covariables. Following subtraction of the HLB, the anterior insula and the anterior cingulate cortex (ACC) but not the somatosensory cortices maintained parametric neural responses to thermal hyperalgesia. A stronger pain-related activity increase during self-administered stimuli was observed in the posterior insula. In contrast, prefrontal cortex showed stronger increases to uncontrollable external heat stimuli. In the state of ongoing pain (capsaicin), pain-intensity-encoding regions (anterior insula, ACC) but not those with sensory discriminative functions (SI, SII) showed graded, pain-intensity-related neural responses in thermal hyperalgesia. Some areas were able to dissociate between self- and externally administered stimuli in thermal hyperalgesia, which might be related to differences in perceived controllability. Thus, neural mechanisms maintain the ability to dissociate external from self-generated states of injury in thermal hyperalgesia. This may help to understand how cognitive strategies potentially alleviate chronic pain syndromes. [source] Counterfactuals and roles: mock victims' and perpetrators' accounts of judicial casesEUROPEAN JOURNAL OF SOCIAL PSYCHOLOGY, Issue 3 2001Patrizia Catellani Three studies assessed the influence of differential perspective taking on counterfactual thinking. In Study 1 male and female subjects were asked to play the role of, respectively, perpetrator and victim in a rape case, and to give their own account of the event. Analysis of spontaneous counterfactuals showed a main tendency to focus on actions more than inactions and on controllable more than uncontrollable elements. However, this tendency was moderated by the subject's role and the counterfactual target. While victims focused on perpetrators' controllable actions more than on their own, perpetrators did not focus on victims' controllable actions more than on their own; they focused on victims' controllable inactions instead. In Study 2, where males and females were asked to reverse their roles, and where prompted as well as spontaneous counterfactuals were analysed, the same results were found. Further evidence for generality of these results was found in Study 3, where an assault case instead of a rape case was taken into account. These findings support the view that counterfactual mutability may be influenced by role-based motivations, as well as by role-based expectations regarding how active a party is supposed to have been in an event. Copyright © 2001 John Wiley & Sons, Ltd. [source] Magnetic forces and moving body induced voltages: applications to velocity sensing and DC,AC conversionEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 6 2010J. A. Brandão Faria Abstract This research and tutorial paper illustrates two interlinked phenomena of the greatest importance for power and energy systems engineers, i.e., magnetic forces and moving body induced voltages. A two-solenoid system with driving and sensing parts is analyzed taking into account that a moving ferromagnetic core can freely move along the system axial coordinate. At first-order approximation the frequency of the oscillating core movement is shown to be linearly controllable by the direct-current intensity injected in the driving solenoid. On the other hand the induced voltage on the sensing solenoid is shown to be a sinusoidal voltage with a frequency twice the one of the moving core. Copyright © 2009 John Wiley & Sons, Ltd. [source] Triplex Au,Ag,C Core,Shell Nanoparticles as a Novel Raman LabelADVANCED FUNCTIONAL MATERIALS, Issue 6 2010Aiguo Shen Abstract Monodispersed, readily-grafted, and biocompatible surface-enhanced Raman spectroscopic (SERS) tagging materials are developed; they are composed of bimetallic Au@Ag nanoparticles (NPs) for optical enhancement, a reporter molecule for spectroscopic signature, and a carbon shell for protection and bioconjugation. A controllable and convenient hydrothermal synthetic route is presented to synthesize the layer-by-layer triplex Au,Ag,C core,shell NPs, which can incorporate the Raman-active label 4-mercapto benzoic acid (4-MBA). The obtained gold seed,silver coated particles can be coated further with a thickness-controlled carbon shell to form colloidal carbon-encapsulated Aucore/Agshell spheres with a monodisperse size distribution. Furthermore, these SERS-active spheres demonstrated interesting properties as a novel Raman tag for quantitative immunoassays. The results suggest such SERS tags can be used for multiplex and ultrasensitive detection of biomolecules as well as nontoxic, in vivo molecular imaging of animal or plant tissues. [source] Orientation Control of Linear-Shaped Molecules in Vacuum-Deposited Organic Amorphous Films and Its Effect on Carrier MobilitiesADVANCED FUNCTIONAL MATERIALS, Issue 3 2010Daisuke Yokoyama Abstract The molecular orientation of linear-shaped molecules in organic amorphous films is demonstrated to be controllable by the substrate temperature. It is also shown that the molecular orientation affects the charge-transport characteristics of the films. Although linear-shaped 4,4,-bis[(N -carbazole)styryl]biphenyl molecules deposited on substrates at room temperature are horizontally oriented in amorphous films, their orientation when deposited on heated substrates with smooth surfaces becomes more random as the substrate temperature increases, even at temperatures under the glass transition temperature. Another factor dominating the orientation of the molecules deposited on heated substrates is the surface roughness of the substrate. Lower carrier mobilities are observed in films composed of randomly oriented molecules, demonstrating the significant effect of a horizontal molecular orientation on the charge-transport characteristics of organic amorphous films. [source] Spatial Patterning of the , -Phase in Poly(9,9-dioctylfluorene): A Metamaterials-Inspired Molecular Conformation Approach to the Fabrication of Polymer Semiconductor Optical StructuresADVANCED FUNCTIONAL MATERIALS, Issue 20 2009Gihan Ryu Abstract Materials in which sub-wavelength physical structures, rather than variations in chemical composition, are used to modify the nature of their interaction with electromagnetic radiation form the promising new class of metamaterials. For molecular materials one has an intriguing alternative, namely structuring the conformation or physical geometry of the molecule. In order for this to be an effective methodology one needs the change in conformation i) to engender a significant change in electromagnetic properties and ii) to be spatially controllable to allow patterning of practical structures. In this paper the potential of such an approach is demonstrated through spatial patterning, via masked solvent vapor exposure, of the , -phase conformation in poly(9,9-dioctylfluorene) (PFO). Significantly the conformation change approach preserves a planar film format and is found not to negatively impact on optical gain properties, both very attractive features for optoelectronic and photonic lightwave circuit applications. As a specific demonstration the ability to spatially control the lasing wavelength for samples in which a , -phase conformation is selectively patterned in a glassy PFO film spin coated atop a one-dimensional distributed-feedback grating etched into a spectrosil substrate is shown. [source] Self-Organized Single-Walled Carbon Nanotube Conducting Thin Films with Honeycomb Structures on Flexible Plastic FilmsADVANCED FUNCTIONAL MATERIALS, Issue 2 2009Nobuo Wakamatsu Abstract Complex 1, synthesized from anionic shortened single-walled carbon nanotubes and cationic ammonium lipid dissolved in organic solvents, is cast on pretreated transparent flexible poly(ethylene terephthalate) (PET) films under a higher relative humidity to form thin films with self-organized honeycomb structures. The cell sizes are controllable by changing the experimental conditions. The lipid, which is the cationic part of complex 1, is easily removed by a simple ion-exchange method, while maintaining the basic honeycomb structures. After the ion exchange, the nanotube honeycomb films on PET with thinner skeletons exhibit a dramatic decrease in the surface resistivity from insulating to conducting. Carbon nanotubes with honeycomb structures formed by the self-organization on flexible polymer films are useful in many areas of nanoscience and technology including nanomaterials, nanoelectronics, nanodevices, catalysts, sensors, and so on. [source] Explaining employee turnover in an Asian contextHUMAN RESOURCE MANAGEMENT JOURNAL, Issue 1 2001Naresh Khatri Employee turnover is giving sleepless nights to HR managers in many countries in Asia. A widely-held belief in these countries is that employees have developed ,bad' attitudes due to the labour shortage. Employees are believed to job-hop for no reason, or even for fun. Unfortunately, despite employee turnover being such a serious problem in Asia, there is a dearth of studies investigating it; in particular studies using a comprehensive set of variables are rare. This study examines three sets of antecedents of turnover intention in companies in Singapore: demographic, controllable and uncontrollable. Singapore companies provide an appropriate setting as their turnover rates are among the highest in Asia. Findings of the study suggest that organisational commitment, procedural justice and a job-hopping attitude were three main factors associated with turnover intention in Singapore companies. [source] Performance Measure Properties and Incentive System DesignINDUSTRIAL RELATIONS, Issue 2 2009MICHAEL J. GIBBS We analyze effects of performance measure properties (controllable and uncontrollable risk, distortion, and manipulation) on incentive plan design, using data from auto dealership manager incentive systems. Dealerships put the most weight on measures that are "better" with respect to these properties. Additional measures are more likely to be used for a second or third bonus if they can mitigate distortion or manipulation in the first performance measure. Implicit incentives are used to provide ex post evaluation, to motivate the employee to use controllable risk on behalf of the firm, and to deter manipulation of performance measures. Overall, our results indicate that firms use incentive systems of multiple performance measures, incentive instruments, and implicit evaluation and rewards as a response to weaknesses in available performance measures. [source] DNA Hybrid Nanomachines: Fullerene Attachment Enhances Performance of a DNA Nanomachine (Adv. Mater.ADVANCED MATERIALS, Issue 19 200919/2009) The image shows the developing biocompatible molecules with controllable, accurate, and reproducible molecular motor functions for mobile nanodevices. Seon Jeong Kim and co-workers show on page 1907 that the attachment of fullerene moieties to a single-strand DNA significantly improves the molecular switching and stability of this pH driven enthalpic molecular machine. Hydrophobic interactions between the terminal fullerenes in the folded i-motif conformation increased the machines power stroke and force generated. [source] Design spaces, measures and metrics for evaluating quality of time operators and consequences leading to improved algorithms by design,illustration to structural dynamicsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 14 2005X. Zhou Abstract For the first time, for time discretized operators, we describe and articulate the importance and notion of design spaces and algorithmic measures that not only can provide new avenues for improved algorithms by design, but also can distinguish in general, the quality of computational algorithms for time-dependent problems; the particular emphasis is on structural dynamics applications for the purpose of illustration and demonstration of the basic concepts (the underlying concepts can be extended to other disciplines as well). For further developments in time discretized operators and/or for evaluating existing methods, from the established measures for computational algorithms, the conclusion that the most effective (in the sense of convergence, namely, the stability and accuracy, and complexity, namely, the algorithmic formulation and algorithmic structure) computational algorithm should appear in a certain algorithmic structure of the design space amongst comparable algorithms is drawn. With this conclusion, and also with the notion of providing new avenues leading to improved algorithms by design, as an illustration, a novel computational algorithm which departs from the traditional paradigm (in the sense of LMS methods with which we are mostly familiar with and widely used in commercial software) is particularly designed into the perspective design space representation of comparable algorithms, and is termed here as the forward displacement non-linearly explicit L-stable (FDEL) algorithm which is unconditionally consistent and does not require non-linear iterations within each time step. From the established measures for comparable algorithms, simply for illustration purposes, the resulting design of the FDEL formulation is then compared with the commonly advocated explicit central difference method and the implicit Newmark average acceleration method (alternately, the same conclusion holds true against controllable numerically dissipative algorithms) which pertain to the class of linear multi-step (LMS) methods for assessing both linear and non-linear dynamic cases. The conclusions that the proposed new design of the FDEL algorithm which is a direct consequence of the present notion of design spaces and measures, is the most effective algorithm to-date to our knowledge in comparison to the class of second-order accurate algorithms pertaining to LMS methods for routine and general non-linear dynamic situations is finally drawn through rigorous numerical experiments. Copyright © 2005 John Wiley & Sons, Ltd. [source] The histological features of microwave coagulation therapy: an assessment of a new applicator designINTERNATIONAL JOURNAL OF EXPERIMENTAL PATHOLOGY, Issue 1 2003Benjamin Swift Abstract. Microwave ablation of tumours within the liver may become an adjunct or alternative to resection in patients with primary or secondary cancers. This technique combines the benefits of a large, localized coagulative effect with a single insertion of the applicator, in a significantly shorter time than comparable treatments. A new range of microwave applicators were developed and tested in animal models and both ex-vivo and in-vivo specimens of human liver at resection. At laparotomy, the applicator tip was inserted into normal liver parenchyma and tumours, with each specimen subjected to irradiation for 180 s or more and at varying power outputs. On sectioning an area of spherical blanching was observed around the applicator cavity. Microscopically a zone of coagulative necrosis was seen adjacent to the site of probe insertion. Damage to blood vessels and bile ducts occurred distal to the probe cavity suggesting the passage of heated fluid, a finding that was diminished by temporary occlusion of the hepatic vasculature (a Pringle manoeuvre). Ultra-structural damage was confirmed within the burn zone and selected liver enzymes were shown to be functioning beyond this region. We suggest this indicates the surrounding liver parenchyma is functioning normally and therefore the volume of microwave-induced damage is controllable. We are confident that the new applicator design will allow the effective treatment of larger tumours in a safe and controlled manner with a single application of energy. [source] Reduced-order impulsive control for a class of nonlinear systemsINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 8 2010Yan-Wu Wang Abstract Impulsive control of nonlinear systems is an attractive topic and a number of interesting results have been obtained in the recent years. However, most of the available results need to employ full information of the system states to achieve the desired objectives. In this paper, a reduced-order impulsive control strategy that needs only part of state components is studied for a general class of nonlinear system, which is feasible for the case when some of the system states are not available or controllable. Typical chaotic systems, such as Lorenz system, Chua's oscillator, and Chen's system, are taken as examples. A systematic design scheme is proposed to select the impulsive intervals. After some theoretical analysis, simulation results illustrate the effectiveness of the proposed control scheme. Copyright © 2009 John Wiley & Sons, Ltd. [source] A generalized homogeneous domination approach for global stabilization of inherently nonlinear systems via output feedbackINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 7 2007Jason Polendo Abstract In this paper, we introduce a generalized framework for global output feedback stabilization of a class of uncertain, inherently nonlinear systems of a particularly complex nature since their linearization around the equilibrium is not guaranteed to be either controllable or observable. Based on a new observer/controller construction and a homogeneous domination design, this framework not only unifies the existing output feedback stabilization results, but also leads to more general results which have been never achieved before, establishing this methodology as a universal tool for the global output feedback stabilization of inherently nonlinear systems. Copyright © 2006 John Wiley & Sons, Ltd. [source] Verbal and Nonverbal Impression Management Tactics in Behavior Description and Situational InterviewsINTERNATIONAL JOURNAL OF SELECTION AND ASSESSMENT, Issue 3 2006Helga Peeters This study investigated how structured interview formats, instructions to convey favorable impressions, and applicants' individual differences influenced the use and effectiveness of verbal and nonverbal impression management (IM). Results from 190 people who were screened for a training program demonstrated that interview format affected the kind of tactics used, which in turn positively influenced interviewer evaluations. Behavior description interviews triggered self-focused (and defensive) tactics, whereas situational interviews triggered other-focused tactics. Instructions to convey a desirable impression also enhanced the use of specific tactics (self-focused and other-focused verbal IM tactics) and moderated the effects of individual differences on IM use. IM instructions did not affect nonverbal IM tactics, indicating that nonverbal behavior might be less intentionally controllable in selection situations. [source] Observation of light-induced localized domain-inversion pattern formation in KNbO3JOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2 2009Yunlin Chen It is demonstrated that high-intensity illumination with an Ar-ion laser beam can generate domain-inversion patterning in KNbO3 crystals. With a special laser-assisted micro-manipulation platform, direct patterning of domain-inversion structures without applying any external electric field can be carried out. The domain-nucleation process has been observed, and the process is purely optical, localized, and potentially controllable both in size and in orientation. [source] A Multi-Method, Multi-Hazard Approach to Explore the Uniqueness of Terrorism Risk Perceptions and Worry,JOURNAL OF APPLIED SOCIAL PSYCHOLOGY, Issue 1 2010Jennifer E.C. Lee Developing ways to manage terrorism effectively requires a better understanding of how the public perceives this threat. In the present study, Canadians' perceptions of terrorism risk and 4 other hazards were assessed using a word-association technique and rating scales reflecting key cognitive dimensions of risk (threat, uncertainty, control) and worry reactions. Data were collected in a national telephone survey. Canadians perceived terrorism as posing a lower threat, as more uncertain, and as less controllable, compared to the other hazards. Positive associations of perceived threat and of perceived uncertainty with worry about terrorism were observed. However, perceived control was unexpectedly positively associated with worry about terrorism. The findings also suggest that additional social contextual factors should be examined in future research. [source] A Taxonomy of Equity FactorsJOURNAL OF APPLIED SOCIAL PSYCHOLOGY, Issue 1 2008Philip H. Siegel A perplexing problem with Adams' (1963) equity theory has been the difficulty associated with operationalizing requisite components, perceived employee inputs, and outcomes. This study, involving 352 respondents, produced empirically derived, two-dimensional taxonomies of inputs and outcomes, laying the foundation for identification of key variables. Specifically, the study summarizes a typology of 9 distinct employee inputs perceived as controllable by individuals, including effort, education, attendance, and cooperativeness. Conversely, the study summarizes a typology of 14 distinct outcomes along a continuum of 4 dimensions, including personalized vs. generalized and economic vs. noneconomic characteristics. These typologies and incumbent regression analysis provide insight into the complexities associated with inputs and outcomes in the context of equity theory. [source] Preparation and characterization of a customized cellulose acetate butyrate dispersion for controlled drug deliveryJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 6 2002Siva Vaithiyalingam Abstract The purpose of the present experiment was to prepare and characterize the aqueous-based pseudolatex system of cellulose acetate butyrate (CAB) for controlled drug delivery. Aqueous pseudolatex systems are advantageous over organic-based coating systems because these systems are devoid of criteria pollutants such as carbon monoxide, nitrogen oxides, nonmethane volatile organic compounds, and sulfur dioxide. Pseudolatex was prepared with CAB and polyvinyl alcohol (stabilizer) by a polymer emulsification technique. The stability of pseudolatex was evaluated. Particle size was measured and rheological experiments were conducted. The glass transition temperature, microscopic free volume, permeation coefficient, and mechanical properties of plasticized pseudolatex films were estimated. Surface roughness of coating on inert Nu-Pareil® beads (Ingredient Technology Corp., Mahwah, NJ) was measured as a function of coating weight gain. The CAB Pseudolatex was found to be stabilized by steric forces. From intrinsic viscosity, the thickness of the stabilization layer was estimated. An increase in polymeric particles proportionately decreased the thickness of the stabilization layer. All the essential properties of a coating membrane such as microscopic free-volume fraction, permeability coefficient, mechanical properties, and glass transition temperature were fairly controllable as a function of plasticizer concentration. The pseudolatex dispersion of CAB was stable with negligible sedimentation volume and a particle size of 300 nm. Because CAB is water insoluble and non-ionizable, this pseudolatex can be used for pH-independent coating. The films obtained were strong and flexible for controlled drug delivery applications. Coating with the CAB dispersion reduced the surface roughness of beads but it remained stable as a function of increase in coating weight gain. © 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 91:1512,1522, 2002 [source] Living cationic polymerization of azobenzene-containing vinyl ether and its photoresponsive behaviorJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 21 2005Tomohide Yoshida Abstract The living cationic polymerization of 4-[2-(vinyloxy)ethoxy]azobenzene (AzoVE) was achieved with various Lewis acids in the presence of an ester as an added base. When Et1.5AlCl1.5 was used as a catalyst, the living polymerization system was controllable by UV irradiation as a result of cis and trans isomerization of the azobenzene side groups. Furthermore, an initiating system consisting of SnCl4 and EtAlCl2 realized fast living polymerization of AzoVE. The polymerization rate of this system was 3 orders of magnitude faster than that obtained with Et1.5AlCl1.5. Poly(4-[2-(vinyloxy)ethoxy]azobenzene) was soluble in a diethyl ether/hexane mixture at 25 °C but became insoluble upon irradiation with UV light. This phase-transition behavior was sensitive and reversible upon irradiation with UV or visible light and reflected the change in polarity occurring with cis and trans isomerization of the azobenzene side groups in the polymers. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5138,5146, 2005 [source] Preparation of novel macromonomers and study of their polymerizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 15 2004Guohua Deng Abstract Novel macromonomers of polystyrene and poly(tert -butyl acrylate) containing a methacryloyl group as a polymerizable unit and two chains of the same length were prepared in two steps: the synthesis of the precursors through the atom transfer radical polymerization of styrene and tert -butyl acrylate initiated by 1-hydroxymethyl-1,1-di[(2-bromoisobutyryloxy)methyl] ethane and the esterification of the hydroxyl group in the precursors with methacryloyl chloride. The molecular weight and polydispersity of the macromonomers were controllable because of the living nature of the atom transfer radical polymerization. Gel permeation chromatography, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and hydrolysis confirmed the structure of the novel macromonomers. The homopolymerization and copolymerization of the macromonomers were investigated to prepare branched copolymers in which two chains were grafted from every repeating unit. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3887,3896, 2004 [source] A Raman spectroscopic and combined analytical approach to the restoration of severely damaged frescoes: the Palomino projectJOURNAL OF RAMAN SPECTROSCOPY, Issue 4 2008Howell G. M. Edwards Abstract The deterioration of art objects is normally relatively minor, controllable and attributable to environmental changes or bacterial invasion, and until now there has not been any recorded attempt to analyse an artwork that has been deliberately and significantly destroyed. The analytical problems are correspondingly larger but the potential reward from any information that can be forthcoming is thereby proportionately greater. The 17th Century Palomino frescoes on the vaulted ceiling of the Church of Sant Joan del Mercat in Valencia were largely destroyed by insurgents in the Spanish Civil War in 1936. The ensuing gunfire and a series of seven conflagrations inside the church had a devastating effect upon the artwork, and the surviving areas were also rendered unstable with respect to their detachment from the substrate. During the current restoration project being undertaken on these frescoes, an opportunity was provided for the application of several analytical techniques to secure information about the original pigment palette employed, the technology of application used by Palomino and the changes consequent upon the destruction process. Here, we report for the first time the use of analytical Raman spectroscopy, supported by scanning electron microscopy (SEM) and voltammetry of microparticles, for the combined identification of pigments, binders, substrate treatments and pigment alteration in an important, although badly damaged, wall painting for the informing of the ongoing conservation and restoration strategy. Copyright © 2008 John Wiley & Sons, Ltd. [source] Orientation-Control Synthesis of KTa0.25Nb0.75O3 NanorodsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2010Yong-Ming Hu Single-crystalline KTa0.25Nb0.75O3 (KTN) nanorods with an orthorhombic perovskite structure were synthesized via a polymer-assisted hydrothermal method. The preferred crystallographic orientation of the nanorods were found to be controllable by using different types of polymers in the process; that is, [001]-oriented KTN were obtained upon the use of polyvinyl alcohol (PVA) and [110]-oriented ones were formed with the use of a combination of polyacrylic acid and PVA. The two types of nanorods showed different properties. The [110]-oriented nanorods exhibited a better photocatalytic decolorization efficiency but very likely a lower thermal conductivity (as indicated by the Raman spectrum measurements) than the [001] nanorods. [source] Synthesis of Porous Silicon Nitride with Unidirectionally Aligned Channels Using Freeze-Drying ProcessJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2002Takayuki Fukasawa Porous silicon nitride with macroscopically aligned channels was synthesized using a freeze-drying process. Freezing of a water-based slurry of silicon nitride was done while unidirectionally controlling the growth direction of the ice. Pores were generated subsequently by sublimation of the columnar ice during freeze-drying. By sintering this green body, a porous silicon nitride with high porosity (over 50%) was obtained and its porosity was controllable by the slurry concentration. The porous Si3N4 had a unique microstructure, where macroscopically aligned open pores contained fibrous grains protruding from the internal walls of the Si3N4 matrix. It is hypothesized that vapor/solid phase reactions were important to the formation mechanism of the fibrous grains. [source] | ||||||||||||||||||||||||||||||||||||||||