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161.
Carter SM Lee J Hixson CA Powell DR Wheeler RA Shaw MJ Richter-Addo GB 《Dalton transactions (Cambridge, England : 2003)》2006,(10):1338-1346
We have examined the redox behavior of the osmium and ruthenium compounds (OEP)M(NO)(OEt) and (OEP)M(NO)(SEt) (OEP = octaethylporphyrinato dianion; M = Os, Ru) by cyclic voltammetry and infrared spectroelectrochemistry. The compound (OEP)Os(NO)(OEt) undergoes a single reversible oxidation process in dichloromethane. In contrast, the thiolate compound (OEP)Os(NO)(SEt) undergoes a net irreversible oxidation resulting in formal loss of the SEt ligand. Extended Hückel calculations on crystal structures of these two compounds provide insight into the nature of their HOMOs. In the case of the alkoxide compound, the HOMO is largely metal centered, with 70% of the charge located in the metal's orbital and approximately 25% on the porphyrin ring. However, the HOMO of the thiolate compound consists of a pi bonding interaction between the metal dxz orbital and the px orbital on the sulfur, and a pi antibonding interaction between the metal d orbital and a pi* orbital on NO. The redox behavior of the Ru analogues have been determined, and are compared with those of the Os compounds. 相似文献
162.
V. Dinca A. Palla-Papavlu M. Dinescu J. Shaw?Stewart T. K. Lippert F. Di Pietrantonio D. Cannata M. Benetti E. Verona 《Applied Physics A: Materials Science & Processing》2010,101(3):559-565
This paper presents polymer pixel printing for applications in chemoselective sensors where nanosecond laser direct transfer methods, with a triazene polymer (TP) acting as a Dynamic Release Layer (DRL), are used. A systematic study of laser fluence, donor film morphology and both single- and multiple-pixel deposition were optimized with the final goal to obtain continuous pixels of sensitive polymers, polyethylenimine (PEI) and polyisobutylene (PIB), on SAW surfaces. Morphology characterization after the laser transfer has been performed by Optical Microscopy and Scanning Electron Microscopy (SEM). The responses of the coated transducers were measured after deposition with different laser fluences and it was found that a fluence under 625 mJ/cm2 was required in order to prevent damage of the interdigital transducers (IDT) of the sensor devices. The sensitivity of the polymer coated devices to acetone concentrations gives an indication that LIFT can be used for printing sensitive polymer pixels onto transducer devices. 相似文献
163.
Andrés F. Lasagni Peng Shao Charles M. Shaw Suman Das 《Applied Surface Science》2010,256(6):1708-9305
A simple optical interference method for the fabrication of simply periodic and periodic with a substructure on poly(3,4-ethylene dioxythiophene)-poly(styrene sulfonate) using femtosecond laser interference patterns is demonstrated. The femtosecond laser pulse was split by a diffractive beam splitter and overlapped with two lenses. Homogeneous periodic arrays could be fabricated even using a single laser pulse. In addition, multipulse irradiation resulted in reproducible sub-wavelength ripples oriented perpendicularly to the laser polarization with spatial period from 170 to 220 nm (around one-fourth of the laser wavelength). In addition, the observed size of the spatial period was not affected by the number of incident laser pulses or accumulated energy density. Using high energy pulses it was possible to completely remove the PEDOT:PSS layer without inducing damage to the underneath substrate. 相似文献
164.
Zwanziger JW Shaw JL Werner-Zwanziger U Aitken BG 《The journal of physical chemistry. B》2006,110(41):20123-20128
Germanophosphate (GeO2-P2O5) glasses were studied with neutron diffraction, phosphorus, and oxygen nuclear magnetic resonance, calorimetry, viscosity measurements, and first-principles calculations. These data sets were combined to propose a structural model of GeO2-P2O5 glasses, which includes tetrahedrally coordinated phosphorus, formation of octahedrally coordinated germanium as P2O5 content increases, an absence of trigonally coordinated oxygen, and hence an absence of rutile-like GeO2 domains. The structural model was then used to propose explanations for both the observed composition dependence of the glass transition temperature and the fragility of the GeO2-P2O5 liquids. 相似文献
165.
Jeong YG Ramalingam S Archer J Hsu SL Paul CW 《The journal of physical chemistry. B》2006,110(6):2541-2548
The influence of copolymer configuration on the phase behavior of various ternary polymer blends containing a crystallizable polyester, a noncrystallizable polyether, and an acrylic random copolymer of different chain configuration was investigated. In these ternary blends, the acrylic random copolymer is typically added to control rheological properties at elevated temperatures. In fact, the acrylic random copolymers composed of various compositions of MMA and nBMA were found to have different miscibility with polyester as well as polyether, leading to substantially different phase behavior of ternary blends. Remarkable temperature dependence was also found. The mean-field Flory-Huggins theory for the free energy of mixing, extended to ternary polymer blends, was adopted for predicting phase diagrams where the exact spinodal and binodal boundaries could be calculated. Phase diagrams of ternary blends, predicted by the Flory-Huggins formulations and related calculations, were in good agreement with experimental phase diagrams. The differences observed in the rheological processes of various ternary blends with different acrylic copolymers were directly related to changes in miscibility, associated phase behavior, and chain configuration. 相似文献
166.
ABSTRACTBayfol (PC-PBT blend ?lm) is a class of polymeric solid-state nuclear track detector which has a lot of applications in several radiation detection ?elds. It is a bisphenol-A polycarbonate PC blended with polybutylene terephthalate PBT. Bayfol/Palladium (PC-PBT/Pd) nanocomposite films have been deposited using the molding technique. It is worth mentioning that this report is almost the first one dealing with the topic of the changes of physical properties of Bayfol/Pd nanocomposite due to laser exposure. Samples from PC-PBT/Pd (5?wt%) nanocomposite were exposed to IR-pulsed laser of 5-W power, capable of producing 2000 pulses per second with pulse duration of 200?ns at 904?nm. The laser fluences were in the range 2–25?J/cm2. The resultant modi?cations in the exposed nanocomposite samples have been studied as a function of fluence using different characterization techniques such as X-ray diffraction (XRD), UV spectroscopy and color difference studies. The results indicate the proper dispersion of Pd nanoparticles in the PC-PBT matrix that causes a strong intermolecular interaction between Pd and PC-PBT, resulted in an increase in refractive index and the amorphous phase. Also, it is found that the laser exposure reduces the optical energy gap that could be attributed to the increase in structural disorder of the exposed PC-PBT/Pd nanocomposites due to crosslinking. Further, the color intensity ΔE, which is the color difference between the exposed samples and the non-exposed one, was increased with increasing the laser fluence, convoyed by a significant increase in the green and yellow color components. 相似文献
167.
J. S. Sanghera L. B. Shaw L. E. Busse V. Q. Nguyen P. C. Pureza B. C. Cole B. B. Harrison I. D. Aggarwal R. Mossadegh F. Kung D. Talley D. Roselle R. Miklos 《Fiber and Integrated Optics》2013,32(3):251-274
Chalcogenide glass fibers based on sulphide, selenide, telluride, and their rare earth doped compositions are being actively pursued both at the Naval Research Laboratory in Washington, D.C. (NRL) and worldwide. Great strides have been made in reducing optical losses using improved chem ical purification techniques, but further improvements are needed in both purification and fiberization technology to attain the theoretical optical losses. Despite this, current singlemode and multimode chalcogenide glass fibers are enabling numerous applications. Some of these applications include laser power delivery, chemical sensing, imaging, scanning near field microscopy spectroscopy, fiber infrared (IR) sources lasers, amplifiers, and optical switches. The authors assert that the research and development of chalcogenide glasses will grow in the foreseeable future, especially with respect to improvements the optical quality of the fibers and the performance of the fibers in existing future applications. 相似文献
168.
169.
Earthquakes, hurricanes, flooding and terrorist attacks continue to threaten our society and, when the worst happens, lives depend on different agencies to manage the response. The literature shows that there is significant potential for operational research (OR) to aid disaster management and that, whilst some of this potential has been delivered, there is more that OR can contribute. In particular, OR can provide detailed support to analysing the complexity of information processing – an essential topic as failure could cause response agencies to act on low quality information or act too slowly – putting responders and victims at risk. However, there is a gap in methods for analysing information processing whilst delivering rapid response. This paper explores how OR can fill this gap through taking a Viable System Model (VSM) approach to analyse information processing. It contributes to the OR literature by showing how VSM can support the analysis of information processing as well as how the OR modelling technique can be further strengthened to facilitate the task. 相似文献
170.
Kuan‐Lin Chen Cheng‐Yu Yeh Shaw‐Hwa Hwang Long‐Jhe Yan 《Mathematical Methods in the Applied Sciences》2013,36(14):1851-1861
This work presents a study of Mandarin speech focusing on consistency analysis of the spectrum and prosody within syllables. Identified as a result of inspection of the human pronunciation process, this consistency can be interpreted as a high correlation between the warping curves of the spectrum and the prosody intra a syllable. The consistency analysis consisted of three steps. First, the hidden Markov model algorithm was used to decode the hidden Markov model‐state sequences within a syllable, while at the same time dividing them into three segments. Second, based on a designated syllable, the vector quantization (VQ) with the Linde–Buzo–Gray algorithm was employed to train the VQ codebooks of the prosodic vector of each segment. Third, the prosodic vector of each segment was encoded as an index using the VQ codebooks, and then, to analyze the consistency, the probability of each possible path was evaluated as a prerequisite. Finally, two syllables were used as examples to verify the consistency property found in the experiments. It is demonstrated experimentally that there is definitely consistency in the case where the syllable is located in exactly the same word. These results offer a research direction in that the warping process between the spectrum and the prosody intra a syllable must be considered in text‐to‐speech systems to improve the synthesized speech quality. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献