Benzodithiophene Copolymer—A Low‐Temperature,Solution‐Processed High‐Performance Semiconductor for Thin‐Film Transistors

Poly(4,8‐didodecyl‐2,6‐bis‐(3‐methylthiophen‐2‐yl)‐benzo[1,2‐b:4,5‐b′]dithiophene) self‐assembled on appropriate substrates from solution and formed highly structured thin films at low temperatures. As an as‐prepared thin‐film semiconductor without thermal annealing, it exhibited excellent field‐effect transistor properties with mobility of ～ 0.15 cm² V^–1 s^–1 in thin‐film transistors.     

Fusion of digital television,broadband Internet and mobile communications—Part II: Future service scenarios

This is the second part of the tutorial paper following the previous tutorial paper describing enabling technologies in digital video broadcasting (DVB) system. The paper presents the current and future operational scenarios for DVB via satellite (DVB‐S) system. Review of the current state‐of‐the‐art technologies consisting of integration of broadband Internet and mobile communications and integration of broadband Internet and DVB are given. The future operational scenarios emphasize the fusion of DVB systems with other technologies in terms of network fusion and terminal fusion. For satellite service scenarios, it also takes into consideration mobility management and standard quality‐of‐service mechanism issues, such as integrated services and differentiated services. Several research directions for providing seamless services regardless of network, access technology and terminal in the fusion network are also highlighted in this paper. Copyright © 2007 John Wiley & Sons, Ltd.     

Analytical evaluation of aircraft operational risks from runway rutting

Runway surface distortions such as rutting allow water to accumulate on the runway surface which may cause aircraft operational risks related to hydroplaning and loss of friction. This may increase the runway excursion risk during wet weather conditions. Several standards relating to airfield pavement maintenance have documented that rutting can cause safety hazards to aircrafts due to hydroplaning risk. This paper proposes an analytical approach to evaluate the hydroplaning potential for aircrafts due to the flooded ruts of a runway pavement and evaluate the operational risk. A finite element model is developed to simulate aircraft tyre hydroplaning under given set of operating conditions. By performing this evaluation for different rut depths, an assessment of the relative severity levels of different rut depths with respect to hydroplaning can be made. A numerical example is presented to illustrate the application of the procedure to evaluate operational risks to aircraft from runway rutting.     

Measurements of thermal diffusivity of boron-silicon film-on-glass structure using phase detection method of photothermal deflection spectroscopy

The phase detection method of photothermal deflection spectroscopy in the transverse configuration was used to measure the overall thermal diffusivity of silicon-boron (Si-B) alloy film on Corning 7059 glass substrate. Results were attained by observing the phase of deflection of the probe beam when it scanned above the film surface relative to the pump beam. Measurements were repeated for different modulation frequencies of the pump beam. Furthermore, both bouncing and skimming configurations were used. The effect of varying the distance between the probe beam and film surface was investigated.     

A class of discrete distributions arising from difference of two random variables

This paper considers a class of distributions arising from the difference of two discrete random variables belonging to the Panjer family of distributions. Some distributional properties and computation of probabilities are discussed. Goodness of fit and tests of hypotheses involving the likelihood ratio, score and Wald tests have been considered. As an illustration, an application to paired count data is given.     

苯乙烯-丁二烯乳液与硅灰共掺混凝土的耐久性研究

采用雾室养护和自然养护两种方式,研究了苯乙烯-丁二烯乳液(SB-latex)与硅灰(silicon fume)共掺时,其掺量对混凝土抗水渗透、抗氯离子渗透、抗碳化和抗硫酸腐蚀性能的影响。试验结果表明苯乙烯-丁二烯乳液和硅灰的共掺可显著地改善混凝土的渗透性,不过SB-latex和硅灰掺量较大时,会分别对混凝土的抗硫酸腐蚀和抗碳化性能产生一定的不利影响。     

Interactive graphic cad for tension structures

This paper reviews the development and application of an interactive CAD system for the form-finding, load analysis and patterning of tensile coated fabric membrane structures. Particular emphasis is given to the integration of all design aspects ranging from form visualization to the production of fabrication patterns within the single CAD system.     

Microscopic Visualization Technique to Predict the Permeation of Organic Solvents through PVC Pipes in Water Distribution Systems

Organic contaminants may permeate through plastic pipes in water distribution systems and adversely affect the quality of drinking water. In this study, we developed a microscopic visualization technique to investigate the permeation of common organic contaminants (benzene, toluene, ethylbenzene, xylene, and trichloroethene) through polyvinyl chloride (PVC) pipes. By observing the propagation of organic moving fronts in the pipe materials with a light microscope, the technique was able to predict the permeation breakthrough times through PVC pipes that were determined in the pipe-bottle test. The advance of an organic moving front was found to be linearly dependent on the square-root of time and the propagation rate increased with an increase in the external organic chemical activity. Permeation of organic mixtures into PVC pipes was found to be additive in proportion to the permeation rates and volume percents of each component. In combination with a 2-year pipe-bottle test for PVC pipes exposed to premium gasoline, mathematical extrapolations based on the microscopic visualization tests predicted that PVC pipe are likely to resist permeation by commercial gasoline for the service life of the pipe.     

Bone cell attachment and growth on well‐characterized chitosan films

Chitosan has been widely researched for bone tissue and implant applications. While initial results are promising, there are inconsistent reports regarding the biological responses. This may be due to inadequate evaluation of chitosan material properties. This study evaluated normal human osteoblast precursor cell attachment and proliferation on a series of well‐characterized chitosan films. The chitosan films exhibited a range of properties: 76–96% degree of de‐acetylation (DDA), 2400–8200 kDa viscosity‐average molecular weight, 62–90° contact angle, 0.24–2.46% residual ash, 5.3–287 µg cm^?2 residual protein and 23–40% crystallinity. There was no trend or correlation between DDA, crystallinity, contact angle, molecular weight, residual ash or protein content and the attachment or growth of bone cells on chitosan films. All films supported higher levels of bone cell proliferation than tissue culture plastic, which supports the general hypothesis that chitosans are osteocompatible. The 78 and 92% DDA chitosan films supported the most cell proliferation, approximately 16 times that of tissue culture plastic controls, but no chitosan physiochemical property correlated with the increased cell growth. The lack of correlation is hindered since more than one physiochemical property changed for each chitosan material. Data do indicate that there may be much variability in chitosan materials, and this variability may make understanding and comparing biological performance of chitosan materials difficult. These results highlight the need for systematic characterizations of chitosan materials for predictable biomedical applications. Copyright © 2006 Society of Chemical Industry