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Selected AbstractsElectrochemical Properties of Ordered Mesoporous Carbon Film Adsorbed onto a Self-Assembled Alkanethiol Monolayer on Gold ElectrodeELECTROANALYSIS, Issue 2 2009Dan Zheng Abstract A stable ordered mesoporous carbon (OMC) film electrode was successfully constructed by adsorbing OMC onto a self-assembled monolayer (SAM) of C18H37SH chemisorbed on the Au electrode. Transmission electron microscopy (TEM), atomic force microscopy (AFM), and electrochemical methods were used to characterize the properties of the OMC film electrode. The adsorbed OMC can restore the heterogeneous electron transfer almost totally blocked by the alkanethiol monolayer. Nyquist plots show a sharply decrease of the charge transfer resistance (Rct) of the Fe(CN) couple at the OMC film electrode. Furthermore, the OMC film electrode is found to possess a significantly reduced interfacial capacitance and largely enhanced current response of hydrogen peroxide. This novel approach to the fabrication of stable OMC film electrode with excellent electrochemical properties is believed to be very attractive for electrochemical studies and electroanalytical applications. [source] Incorporation of Disposable Screen-Printed Electrodes for Use in Capillary Electrophoresis End-Column Amperometric Detection SystemELECTROANALYSIS, Issue 21 2005Dong-Mung Tsai Abstract The development and performance of an end-column amperometric detection system integrated with disposable screen-printed electrodes for capillary electrophoresis is presented. In this system, the electrode and capillary can be easily replaced and the capillary/electrode alignment procedure is straightforward. The use of easily replaceable screen-printed electrodes offers a tremendous benefit for capillary electrophoresis applications requiring frequent replacement of the working electrode due to fouling. This simple and convenient system is very attractive for routine analyses by capillary electrophoresis with electrochemical detection. The separation and determination of uric acid in human urine is presented. [source] Electrochemical Nitric Oxide Sensors for Biological Samples , Principle, Selected Examples and ApplicationsELECTROANALYSIS, Issue 1 2003Fethi Bedioui Abstract The discoveries made in the 1980s that NO could be synthesized by mammalian cells and could act as physiological messenger and cytotoxic agent had elevated the importance of its detection. The numerous properties of NO, that enable it to carry out its diverse functions, also present considerable problems when attempting its detection and quantification in biological systems. Indeed, its total free concentration in physiological conditions has been established to be in nanomolar range. Thus, detection of nitric oxide remains a challenge, pointing out the difficult dual requirements for specificity and sensitivity. Exception made for the electrochemical techniques, most of the approaches (namely UV-visible spectroscopy, fluorescence, electron paramagnetic resonance spectroscopy) use indirect methods for estimating endogenous NO, relying on measurements of secondary species such as nitrite and nitrate or NO-adducts. They also suffer from allowing only ex situ measurements. So, the only strategies that allow a direct and in vivo detection of NO are those based on the use of ultramicroelectrodes. The reality is that surface electrode modification is needed to make the ultramicroelectrode material selective for NO. Therefore, the design of modified electrode surfaces using organized layers is very attractive and provides the ideal strategy. This review addresses a global description of the various approaches that have involved chemically modified microelectrodes specially designed for the electrochemical detection of NO in biological media. Selected significant examples of applications in biological tissues are also reported in order to highlight the importance of this approach in having new insights into the modulatory role of NO in physiology and pathophysiology. [source] Synthesis of Cobalt/Polymer Multilayer Nanotubes,ADVANCED ENGINEERING MATERIALS, Issue 4 2005K. Nielsch Cobalt/polymer multilayer nanotubes (see Figure) are formed by wetting of alumina and silicon membranes by polystyrene containing a metallo,organic precursor, followed by a thermal decomposition process. This article describes the fabrication and magnetic properties of high quality, thin-walled ferromagnetic nanotubes. They might be very attractive for a broad range of potential applications ranging from biotechnology to magnetic storage devices. [source] Evaluation of drugs in pediatrics using K-PD models: perspectivesFUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 6 2008M. Tod Abstract Some pharmacodynamic (PD) models, called K-PD models, have been developed for the description of drug action kinetics in the absence of drug concentration measurements. Because blood samples for drug measurements are not needed, these models may be very useful in pediatric studies, by reducing their invasiveness. In addition, a number of PD measurements are also non-invasive and specific devices exist for measures in children. Therefore, the kinetics of drug action may be characterized with minimal invasiveness. A brief description of the key features of these models is given, and a number of examples of application are presented. K-PD models are expected to be most useful when the drug kinetics is simple (i.e. when the one-compartment model is a reasonable description), or when the response kinetics is slow compared with drug kinetics. K-PD models have already demonstrated their usefulness in animal and adult studies. They are very attractive for pediatric studies and they should facilitate the assessment of drug efficacy and safety. [source] Oral Vaccination Against Helicobacter pylori with Recombinant Cholera Toxin B-SubunitHELICOBACTER, Issue 4 2005Eiji Kubota ABSTRACT Background., The innocuous pure recombinant cholera toxin B-subunit (rCTB) is very attractive as a strong adjuvant for host immunization, but little is known about rCTB's gastric mucosal immunoadjuvanticity against Helicobacter pylori. The immunoadjuvanticity of rCTB against H. pylori was tested. Material and methods., Mice were immunized with sonicated H. pylori and rCTB orally or intranasally and sacrificed on day 42 after immunization. Passive cutaneous anaphylaxis (PCA) test was performed to evaluate IgE-mediated anaphylaxis with serum from mice to which H. pylori -antigen with rCTB had been administered. Immunoglobulin titer specific to H. pylori in serum, lavation of the gastrointestinal tracts and feces were examined. Gastritis in vaccinated mice after a challenge was assessed with the scoring defined from grading of gastric inflammation. H. pylori proliferation after immunization was investigated by counting colony forming units (CFU) per gram of stomach tissue. Results., PCA test exhibited no reactions against the serum from mice immunized with H. pylori -antigen with rCTB administered orally and intranasally. Oral and nasal coadministrations of rCTB significantly raised systemic and mucosal immunities against H. pylori and suppressed proliferation of H. pylori in gastric mucosa. The score of gastritis in mice immunized orally was significantly higher than that of mice immunized nasally due to postimmunization gastritis. Only oral administration of rCTB suppressed H. pylori proliferation as compared with intranasal administration and without rCTB. Conclusions., The present study indicated that rCTB has systemic and mucosal immunoadjuvanticities against H. pylori and that oral vaccination with rCTB might additively support antibiotic eradication. [source] Stimuli-Responsive Porous Hydrogels at Interfaces for Molecular Filtration, Separation, Controlled Release, and Gating in Capsules and MembranesADVANCED MATERIALS, Issue 31 2010Ihor Tokarev Abstract A continuously growing area of controlled and tunable transport and separation of biomolecules and drugs has recently attracted attention to the structures which can be referred to as stimuli-responsive porous hydrogel thin films. Because of spatial constraints, swelling/shrinking of the hydrogel films results in closing/opening (or vice versa) of the film's pores. Such responsive systems can be used in the configuration of plane films or capsules. The combination of a low thickness (translating into a low hydrodynamic flow resistance and rapid response) with well-defined size and shape of pores (translating into better control of transport and separation), which can be closed, opened, or tuned by an external signal (allowing a large amplitude of changes in diffusivity of solutes in the thin film and a precise control of the pore size), makes these materials very attractive for a range of applications, such as molecular filtration, separation, drug delivery, sensors, and actuators. [source] Progress in the Field of Electrospinning for Tissue Engineering ApplicationsADVANCED MATERIALS, Issue 32-33 2009Seema Agarwal Abstract Electrospinning is an extremely promising method for the preparation of tissue engineering (TE) scaffolds. This technique provides nonwovens resembling in their fibrillar structures those of the extracellular matrix (ECM), and offering large surface areas, ease of functionalization for various purposes, and controllable mechanical properties. The recent developments toward large-scale productions combined with the simplicity of the process render this technique very attractive. Progress concerning the use of electrospinning for TE applications has advanced impressively. Different groups have tackled the problem of electrospinning for TE applications from different angles. Nowadays, electrospinning of the majority of biodegradable and biocompatible polymers, either synthetic or natural, for TE applications is straightforward. Different issues, such as cell penetration, incorporation of growth and differentiating factors, toxicity of solvents used, productivity, functional gradient, etc. are main points of current considerations. The progress in the use of electrospinning for TE applications is highlighted in this article with focus on major problems encountered and on various solutions available until now. [source] A new damage model based on non-local displacementsINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 5 2005Antonio Rodríguez-Ferran Abstract A new non-local damage model is presented. Non-locality (of integral or gradient type) is incorporated into the model by means of non-local displacements. This contrasts with existing damage models, where a non-local strain or strain-related state variable is used. The new model is very attractive from a computational viewpoint, especially regarding the computation of the consistent tangent matrix needed to achieve quadratic convergence in Newton iterations. At the same time, its physical response is very similar to that of the standard models, including its regularization capabilities. All these aspects are discussed in detail and illustrated by means of numerical examples. Copyright © 2005 John Wiley & Sons, Ltd. [source] High Aspect-Ratio Cylindrical Nanopore Arrays and Their Use for Templating Titania Nanoposts,ADVANCED MATERIALS, Issue 4 2008O.-H. Park Well-defined arrays of titania nanoposts are generated by using high aspect-ratio cylindrical nanopore templates. The simple and controllable fabrication scheme of the nanoporous templates makes them very attractive for creating well-defined nanostructures out of a variety of functional materials. The arrays of titania nanoposts can find a variety of applications such as photonic crystals, photocatalysts, and photovoltaics. [source] Bandwidth-efficient turbo coding over Rayleigh fading channelsINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 7 2002Stéphane Y. Le Goff Abstract Introduced in 1993, turbo codes can achieve high coding gains close to the Shannon limit. In order to design power and bandwidth-efficient coding schemes, several approaches have been introduced to combine high coding rate turbo codes with multilevel modulations. The coding systems thus obtained have been shown to display near-capacity performance over additive white Gaussian noise (AWGN) channels. For communications over fading channels requiring large coding gain and high bandwidth efficiency, it is also interesting to study bit error rate (BER) performance of turbo codes combined with high order rectangular QAM modulations. To this end, we investigate, in this paper, error performance of several bandwidth-efficient schemes designed using the bit-interleaved coded modulation approach that has proven potentially very attractive when powerful codes, such as turbo codes, are employed. The structure of these coding schemes, termed ,bit-interleaved turbo-coded modulations' (BITCMs), is presented in a detailed manner and their BER performance is investigated for spectral efficiencies ranging from 2 to 7 bit/s/Hz. Computer simulation results indicate that BITCMs can achieve near-capacity performance over Rayleigh fading channels, for all spectral efficiencies considered throughout the paper. It is also shown that the combination of turbo coding and rectangular QAM modulation with Gray mapping constitutes inherently a very powerful association, since coding and modulation functions are both optimized for operation in the same signal-to-noise ratio region. This means that no BER improvement is obtainable by employing any other signal constellation in place of the rectangular ones. Finally, the actual influence of the interleaving and mapping functions on error performance of BITCM schemes is discussed. Copyright © 2002 John Wiley & Sons, Ltd. [source] Elastomeric Molds with Tunable Microtopography,ADVANCED MATERIALS, Issue 23-24 2004M. Hoffman Elastomeric "microtunable" molds (,TMs) whose microtopography can be tuned post-fabrication at certain pre-defined locations have been devised. Their features make them very attractive for the molding of complex microstructures. The Figure shows a scanning electron microscopy image of poly(dimethylsiloxane) double- replicas of a ,TM whose membrane contains a 1.18,mm spiral. [source] Fluorescence spectra of Pr3+ ions in phosphate materials calculated by the DVME methodINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 12 2009Y. Kowada Abstract Recently, fluorescence spectra of rare-earth ions in oxide materials are very attractive for the applications of the optical amplification in optical fiber communications, white LED, etc. However, it has been difficult to calculate the fluorescence spectra of rare-earth ions by the first principle method. In this study, we used the relativistic discrete-variational multielectron (DVME) method, which is a configuration-interaction (CI) calculation program using the molecular orbitals obtained by the relativistic DV-X, method. We applied this method for the calculation of the fluorescence spectrum of the Pr3+ ions in phosphate materials. The transition probability of the fluorescence was calculated in the same manner of the absorption. The obtained theoretical fluorescence spectrum was in good agreement with the experimental one, though the intensity of each peak was deeply dependent on the configuration of the surrounding structural units. The results suggested that the DVME method was useful for the calculation of not only absorption but also fluorescence spectra of rare-earth ions in oxide materials. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 [source] Magnetic resonance microscopy at 17.6-Tesla on chicken embryos in vitroJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 1 2001Bianca Hogers PhD Abstract The non-destructive nature and the rapid acquisition of a three-dimensional image makes magnetic resonance microscopy (MRM) very attractive and suitable for functional imaging investigations. We explored the use of an ultra high magnetic field for MRM to increase image quality per image acquisition time. Improved image quality was characterized by a better signal-to-noise ratio (SNR), better image contrast, and higher resolution compared to images obtained at lower magnetic field strengths. Fixed chicken embryos at several stages of development were imaged at 7.0-T (300 MHz) and at 17.6-T (750 MHz). Maximum intensity projection resulted in three-dimensional vascular images with ample detail of the embryonic vasculature. We showed that at 750 MHz frequency, an image with approximately three times better SNR can be obtained by T1 -weighting using a standard gadolinium contrast agent, compared to the same measurement at 300 MHz. The image contrast improved by around 20 percent and the contrast-to-noise ratio improved by almost a factor of 3.5. Smaller blood vessels of the vascular system were identified at the high field, which indicates a better image resolution. Thus, ultra high field is beneficial for MRM and opens new areas for functional imaging research, in particular when SNR, resolution, and contrast are limited by acquisition time. J. Magn. Reson. Imaging 2001;14:83,86. © 2001 Wiley-Liss, Inc. [source] Recent advancement on polybenzoxazine,A newly developed high performance thermosetJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 21 2009Yusuf Yagci Abstract Polybenzoxazine is a newly developed addition polymerized phenolic system, having a wide range of interesting features and the capability to overcome several shortcomings of conventional novolac and resole type phenolic resins. They exhibit (i) near zero volumetric change upon curing, (ii) low water absorption, (iii) for some polybenzoxazines Tg much higher than cure temperature, (iv) high char yield, (v) no strong acid catalysts required for curing, (vi) release of no byproduct during curing and also possess thermal and flame retarding properties of phenolics along with the mechanical performance. Though benzoxazine based materials possess several advantages, they have not yet became very attractive to the industries. To improve the mechanical properties and processibility several strategies have been reported including (i) synthesis of benzoxazine monomers with additional functionality, (ii) incorporation of benzoxazine in polymer chain, and (iii) benzoxazine based composites or alloys. In this article, we have discussed about the recent development of benzoxazine chemistry. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5565,5576, 2009 [source] Usefulness of a program of hospital-supervised physical training in patients with cystic fibrosisPEDIATRIC PULMONOLOGY, Issue 2 2004Attilio Turchetta MD Abstract Exercise is an important part of normal childhood, but the ability to exercise may be impaired in chronic lung diseases such as cystic fibrosis (CF). Improving exercise performance by training is very attractive. The aim of the present study was the evaluation of the effects of a physical aerobic training program, performed in the Children's Hospital and Research Institute "Bambino Gesù" (Rome, Italy) in outpatient CF children, supervised by a physician. Twelve patients (mean forced expiratory flow in 1 sec (FEV1), 71%), age range 12,24 years (16.7 ± 4.4 years), were enrolled. They performed a maximal exercise stress test on the treadmill (modified Bruce protocol) with breath-by-breath determination of oxygen consumption (VO2) to maximum at end-exercise; we measured time of exercise (TE), maximal heart rate (Hrmax) in beats per minute (bpm), and maximal systolic blood pressure (SBPm) in mmHg. The program consisted of 12 weeks of training twice a week. Each training session consisted of walking or running on the treadmill for 30 min at the speed that allowed the child to attain 60% of the maximal heart rate obtained during a baseline stress test for 4 weeks, 70% in the following 4 weeks, and 80% in the last 4 weeks, under strict medical supervision. HR was continously monitored. There was no change in FEV1 and forced vital capacity after the treatment period. Hrmax and SBPm also remained the same (P,=,0.37 and P,=,0.25, respectively). There was a significant increase in TE (P,<,0.002), VO2, VO2/kg, and pulmonary ventilation (VE) (P,<,0.0001, P,<,0.001, and P,<,0.001, respectively). This pilot study showed that a simple training program improves short-term cardiopulmonary fitness in children with CF. Further studies with a larger sample and for a more prolonged time are necessary to assess if sport can have a long-term effect on lung function or survival in CF patients. Pediatr Pulmonol. 2004; 38:115,118. © 2004 Wiley-Liss, Inc. [source] Remarkable improvement in output power for an InAlGaN based ultraviolet LED by improving the crystalline quality of AlN/AlGaN templatesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2008T. Takano Abstract The use of quaternary InAlGaN is very attractive for the realization of commercially-available low-cost and high-power ultraviolet light-emitting diodes (UV-LEDs), because highly-efficient UV emission can be obtained from this material due to In-segregation effects. We achieved remarkable improvements in output power from 340 nm-band quaternary InAlGaN-based UV-LEDs and demonstrated high UV-output power by using high-quality AlN buffer templates on sapphire substrates. Threading dislocation densities (TDDs) for screw and edge-type dislocations were 1×108cm,2 and 1×109cm,2, as observed from cross-sectional transmission electron microscope (TEM) images. The output power of a 340 nm-band UV-LED was increased by approximately 7 times by reducing the full-width-at-half-maximum (FWHM) of the (10-12) X-ray ,-scan rocking curve (XRC) from around 800 arcsec to 510 arcsec. As a result, we achieved a maximum output power of 7.1 mW under room-temperature (RT) and continuous-wave (CW) operation. From these results, we confirmed that the crystalline quality of AlN/AlGaN templates strongly affects the output power of UV-LEDs. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] PE-CVD of Acid/Base Coatings from Acrylic Acid and Allylamine VapoursPLASMA PROCESSES AND POLYMERS, Issue S1 2007Eloisa Sardella Abstract Different plasma processes were investigated to obtain coatings characterized by N and O functional groups at their surface. From the literature, big efforts are evident devoted to designing new surfaces with chemical composition and chemical,physical properties tightly controlled. This paper demonstrates how it is possible to obtain coatings with acid and basic properties at different extent, by simply adjusting the acrylic acid/allylamine chemical composition of the gas feed in a plasma deposition process. The deposited films exhibit tuneable acid,base properties, very attractive to manufacture sensors, and biomaterials, and for applications in tissue engineering field. [source] Synthesis of azobenzene-functionalized two-arm, three-arm and four-arm telomers using polyfunctional chain transfer agentsPOLYMER INTERNATIONAL, Issue 11 2009Md Zahangir Alam Abstract BACKGROUND: Star-shaped polymers are very attractive because of their interesting properties such as reduced viscosity, good solubility, low glass transition temperature and fast response to external stimuli. The incorporation of azobenzene moieties in star-shaped polymers could significantly widen their potential applications in various optical devices. One of the most important properties of the azobenzene chromophore is its reversible trans,cis photoisomerization induced by UV or visible light. Photoisomerization induces conformational changes in azopolymer chains, which in turn lead to macroscopic variations in chemical and physical properties of the surroundings and media. RESULTS: This study reports the synthesis of azobenzene-functionalized two-, three- and four-arm telomers via free radical telomerization using the di-, tri- and tetrafunctional chain transfer agents 1,2- and 1,4-benzenedimethanethiol, trimethylolpropane-tris(2-mercaptoacetate) and pentaerythritol-tetrakis(3-mercaptopropionate), respectively, in the presence of azobisisobutyronitrile. Azotelomers were characterized using gel permeation chromatography and 1H NMR and Fourier transform infrared spectroscopy. Thermal phase transition behaviors were investigated using differential scanning calorimetry and polarized optical microscopy. Azotelomers synthesized in this study showed reversible photoisomerization and a fast generation of birefringence. CONCLUSION: Considering the photoisomerization behavior and birefringence of the two-, three- and four-arm azotelomers, it can be concluded that they could be potential candidates for use in various optical devices. Copyright © 2009 Society of Chemical Industry [source] Model-free feedback design for a mixed cancer therapyBIOTECHNOLOGY PROGRESS, Issue 3 2009S. Chareyron Abstract In this article, a model-free feedback control design is proposed for the drug administration in mixed cancer therapy. This strategy is very attractive because of the important issue of parameter uncertainties unavoidable when dealing with biological models. The proposed feedback scheme use past measurements to update an on-line simplified model. The control design is then based on model predictive control in which a suitable switching is performed between two different cost functions. The effectiveness of the proposed model-free control strategy is validated using a recently developed model (unknown to the controller) governing the cancer growth on a cells population level under combined immune and chemotherapy and using real human data. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] Performance Characteristics of Nanoporous Carbon Membranes for Protein UltrafiltrationBIOTECHNOLOGY PROGRESS, Issue 5 2007Tapan N. Shah Nanoporous carbon membranes could be very attractive for applications of ultrafiltration in the biotechnology industry because of their greater mechanical strength and longer membrane life. The objective of this study was to obtain quantitative data on the performance characteristics of nanoporous carbon membranes formed within a stainless steel support that was first modified by deposition of silica particles within the macroporous support. The nanoporous carbon membrane effectively removed small solutes from a protein solution using diafiltration, with performance comparable to that of commercial polymeric membranes. Protein fouling was evident, although the nanoporous carbon membranes were easily regenerated; cleaning with 0.5 N NaOH at 50 °C completely restored the water permeability for multiple cycles. The nanoporous carbon membranes were also compatible with steam sterilization. Significant increases in process flux could be obtained using periodic back-pulsing, with no evidence of any structural alterations in the membrane. These results clearly demonstrate the potential benefits and opportunities for using nanoporous carbon membranes for protein ultrafiltration. [source] Women's Views of Pregnancy Ultrasound: A Systematic ReviewBIRTH, Issue 4 2002Jo Garcia MSc ABSTRACT: Background: Ultrasound has become a routine part of care for pregnant women in most countries with developed health services. It is one of a range of techniques used in screening and diagnosis, but it differs from most others because of the direct access that it gives parents to images of the fetus. A review of women's views of ultrasound was commissioned as part of a larger study of the clinical and economic aspects of routine antenatal ultrasound use. Methods: Studies of women's views about antenatal screening and diagnosis were searched for on electronic databases. Studies about pregnancy ultrasound were then identified from this material. Further studies were found by contacting researchers, hand searches, and following up references. The searches were not intentionally limited by date or language. Studies that reported direct data from women about pregnancy ultrasound were then included in a structured review. Studies were not excluded on the basis of methodological quality unless they were impossible to understand. They were read by one author and tabulated. The review then addressed a series of questions in a nonquantitative way. Results: The structured review included 74 primary studies represented by 98 reports. Studies from 18 countries were included, and they employed methods ranging from qualitative interviewing to psychometric testing. The review included studies from the very early period of ultrasound use up to reports of research on contemporary practice. Ultrasound is very attractive to women and families. Women's early concerns about the safety of ultrasound were rarely reported in more recent research. Women often lack information about the purposes for which an ultrasound scan is being done and the technical limitations of the procedure. The strong appeal of diagnostic ultrasound use may contribute to the fact that pregnant women are often unprepared for adverse findings. Conclusions: Despite the highly varied study designs and contexts for the research included, this review provided useful information about women's views of pregnancy ultrasound. One key finding for clinicians was the need for all staff, women, and partners to be well informed about the specific purposes of ultrasound scans and what they can and cannot achieve. (BIRTH 29:4 December 2002) [source] Ion-Exchange Plasma Membranes for Fuel Cells on a Micrometer Scale,CHEMICAL VAPOR DEPOSITION, Issue 6-7 2007S. Roualdès Abstract Recent advances in,miniaturization technology make polymer electrolyte membrane fuel cells very attractive as power sources for portable devices. Ion-exchange membranes for microscale fuel cells are synthesized by plasma polymerization (using a precursor containing ion-exchange groups) and intensively characterized. Ion-exchange plasma membranes are thin, amorphous, and dense materials with no defects. Spectroscopic analyses reveal a polymer-type matrix containing a rather high concentration of ion-exchange groups. Under the best synthesis conditions, membranes show a satisfying ionic conduction level and a high compatibility with other active layers of fuel cells, making them suitable for insertion in such power-supply devices. [source] Biaryls Made Easy: PEPPSI and the Kumada,Tamao,Corriu ReactionCHEMISTRY - A EUROPEAN JOURNAL, Issue 1 2007Michael G. Organ Prof. Abstract An easily employed, highly versatile Kumada,Tamao,Corriu (KTC) protocol utilizing the PEPPSI (Pyridine, Enhanced, Precatalyst, Preparation, Stabilization and Initiation) precatalysts 1 and 2 is detailed. The ease-of-use of these catalysts and the synthesis of a wide range of hindered biaryls, large coupling partners and drug-like heterocycles, in high yield, makes the PEPPSI-KTC protocol very attractive. The high reactivity of the PEPPSI system allowed a tetra- ortho -substituted heterocycle, 11 to be synthesized at room temperature for the first time using any protocol. The PEPPSI protocols also tolerated the Boc protecting group and phenols required no protection in modified conditions. A relatively large scale (10 g) reaction was also performed with no loss in performance. Furthermore, PEPPSI-IPr, 1, was compared to previously reported highly active phosphine ligands 42, 43, and 44 and was shown to result in significantly better yields under identical conditions. Finally, we demonstrated that the PEPPSI catalyst system is very adept at performing sequential KTC coupling reactions, analogous to multicomponent reactions, which allow complex polyaryl and polyheteroaryl architectures to be produced in one single operation. [source] An Asian community's perspective on facial profile attractivenessCOMMUNITY DENTISTRY AND ORAL EPIDEMIOLOGY, Issue 1 2007Jen Soh Abstract,,, Objectives:, To assess the facial profile preferences of laypersons in an Asian community and the influence of age, ethnic and gender on profile selection. Methods:, A sample of 149 laypersons (65.1% Chinese, 21.5% Malays and 13.4% Indians), comprising of 112 females (75.2%) participated in the study. The mean age was 24.6 years (SD 4.4). A facial profile photograph and a lateral cephalometric radiograph of a Chinese male and female adult with a normal profile and a class I incisor and skeletal relationship were digitized to create a baseline template. Computerized digital photographic image modification was carried out on the template to obtain seven facial profiles [bimaxillary protrusion, protrusive mandible, retrusive mandible, normal profile (incisor and skeletal class I pattern), retrusive maxilla, protrusive maxilla and bimaxillary retrusion] for each gender. The laypersons were asked to rank the profiles of each gender on a scale of 1 (very attractive) to 7 (least attractive). Results:, Orthognathic Chinese male and female profiles were perceived to be the most attractive. A male orthognathic profile with normative Chinese cephalometric values was perceived to be more attractive than a ,flatter' bimaxillary retrusive profile. Bimaxillary retrusion and normal Chinese female profiles were perceived to be the most attractive. A male or female profile with a protrusive mandible was judged to be the least attractive. Age, gender and ethnicity were nonsignificant predictors for the most attractive female profile. Conclusions:, Orthognathic Chinese male and female profiles were judged to be the most attractive by Asian adult laypersons. Male and female profiles with mandibular protrusion were judged to be the least attractive. [source] | |||||||||||||||||||||||||||||||