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81.
82.
The effect of clay content, homogenization RPM, and pH on the mechanical and barrier properties of fish gelatin/nanoclay composite films was investigated. The addition of 5% nanoclay (w/w) increased the tensile strength from 30.31 ± 2.37 MPa to 40.71 ± 3.30 MPa. The 9 g clay/100 g gelatin film exhibited the largest improvements in oxygen and water barrier properties. Oxygen permeability decreased from 402.8 × 10−6 ± 0.7 × 10−6 g m/m2 day atm to 114.4 × 10−6 ± 16.2 × 10−6 g m/m2 day atm and the water vapor permeability decreased from 31.2 × 10−3 ± 1.6 × 10−3 ng m/m2 s Pa to 8.1 × 10−3 ± 0.1 × 10−3 ng m/m2 s Pa. The XRD and TEM observation suggested that the ultrasonication treatment (30 min at 40% output) resulted in exfoliation of the silicates. 相似文献
83.
We investigate an extension of predictive control, PID controllers, and Smith predictors to some classes of linear delay systems which are most encountered in practice. The predictive part is provided by extending flatness-based predictive control. Generalized PI regulators lead to a 'PID and Smith predictor'-like scheme which permits us to easily handle (deadtime-dominant) unstable systems. Numerous examples with thorough simulations demonstrate the performance of the proposed control strategy. 相似文献
84.
85.
An important issue concerning the use of soft contact lenses is comfort, which, among other factors, has been related to the
level of friction between the anterior side of the lens and the inner eyelid. Although several studies have been carried out
to investigate the frictional properties of contact lenses, these have not taken the physiological environment of the eye
into account. In use, lenses are in contact with proteins present in tears, with corneal cells and with the palpebral conjunctiva
(clear membrane on inner eyelid). The focus of this study was to establish a biologically relevant measurement protocol for
the investigation of friction of contact lenses that would mimic the eye’s physiological environment. By optimizing parameters
such as the composition of the friction counter surface, the lubricant solution, the normal load and the velocity, an ideal
protocol and setup for microtribological testing could be established and used to perform a comparative study of various commercially
available soft contact lenses. 相似文献
86.
R. C. Nelson D. A. Sergatskov R. V. Duncan 《Journal of Low Temperature Physics》2002,126(1-2):649-654
Measurements of the magnetic sensitivity of thin sputtered films of PdMn alloy demonstrate the viability of this material for high resolution thermometry. The thinnest films (thickness 1.0 m) show significant domain scale noise below the Curie Temperature, Tc, while thicker films (thickness 10 m) show reliable non-hysteretic behavior throughout the temperature range of interest. The thin films show the effects of demagnetization with the field perpendicular to the surface, but a fine screen in this orientation shows good response with no evidence of saturation and a manageable degree of demagnetization. 相似文献
87.
Fairweather JK Faijes M Driguez H Planas A 《Chembiochem : a European journal of chemical biology》2002,3(9):866-873
Bacillus 1,3-1,4-beta-glucanases hydrolyze 1,3-1,4-beta-gluco-oligosaccharides with a retaining mechanism. The binding-site cleft of these endoglycosidases is composed of six subsites (-4 to +2) of which subsite -3 makes the largest contribution to transition state stabilization. The specificity of this subsite is here analyzed for both glycosidase and glycosynthase activities in the wild-type and the nucleophile-less E134A mutant Bacillus licheniformis enzymes. A D-galactosyl residue on the nonreducing end of a trisaccharide substrate is accepted by the enzyme and binds at subsite -3 in the productive enzyme-substrate complex. The wild-type enzyme catalyzes the hydrolysis of the substrate Glcbeta4Glcbeta3GlcbetaMU (Glc=glucosyl, MU=4-methylumbelliferyl) with a k(cat)/K(M) value only 1.3-fold higher than for the Galbeta4Glcbeta3GlcbetaMU (Gal=galactosyl) substrate. The corresponding alpha-fluorides act as good donors for the glycosynthase condensation reaction with mono- and disaccharide acceptors catalyzed by the E134A mutant. Whereas self-condensation and elongation products are also obtained as minor compounds with the Glcbeta4Glcbeta3GlcalphaF donor, nearly quantitative yields of single condensation products are obtained with the Galbeta4Glcbeta3GlcalphaF donor, in which the axial configuration of the 4-OH group on the nonreducing end prevents self-condensation and elongation reactions. 相似文献
88.
G. Stanley Hall influenced several social movements that had great implications for child wellbeing: the Child Study, Parent Education, and Child Welfare Movements. However, while Hall laid much of the foundation for the field of scientific child study and policy-relevant research, his legacy is virtually nonexistent. The current article reviews the life and contributions of G. Stanley Hall, and the dual role Hall played in history as a revered leader of the Child Study Movement and a controversial figure in the landscape of early child psychology. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
89.
90.
Shape is an important consideration in green building design due to its significant impact on energy performance and construction costs. This paper presents a methodology to optimize building shapes in plan using the genetic algorithm. The building footprint is represented by a multi-sided polygon. Different geometrical representations for a polygon are considered and evaluated in terms of their potential problems such as epistasis, which occurs when one gene pair masks or modifies the expression of other gene pairs, and encoding isomorphism, which occurs when chromosomes with different binary strings map to the same solution in the design space. Two alternative representations are compared in terms of their impact on computational effectiveness and efficiency. An optimization model is established considering the shape-related variables and several other envelope-related design variables such as window ratios and overhangs. Life-cycle cost and life-cycle environmental impact are the two objective functions used to evaluate the performance of a green building design. A case study is presented where the shape of a typical floor of an office building defined by a pentagon is optimized with a multi-objective genetic algorithm. 相似文献