Absorption of water by graft copolymers of cotton with methyl methacrylate using high-resolution NMR

Graft cotton fibers containing poly(methyl methacrylate) were initiated by ultraviolet radiation. High-resolution NMR was used to study the nature of water absorption by these graft copolymers and also by mixtures of cotton fibers with the corresponding homopolymers. Results obtained help in investigating the structure of the copolymers and to differentiate, in a simple way, between true graft copolymers and mechanical mixtures or coated fibers.     

Significance of COD, BOD and TOC correlations in kinetic models of biological oxidation

The results of pilot scale studies on the activated-sludge process have been analysed to determine correlations between BOD, COD and TOC at various stages of treatment. The nature of the correlations observed suggests that the interchangeable use of these parameters in models of biological oxidation is not advisable.     

Transient failure analysis of liquid-filled shells Part I: Theory

In this paper, the governing equations which consider dynamic fluid-structure interaction, modal coupling in both axial and circumferential directions, and dynamic buckling are derived. The various pressure components acting on the shell wall due to a seismic event are also analyzed. The matrix equation of motion for liquid-filled shells is obtained through a Galerkin/Finite Element discretization procedure. The modal coupling among the various combinations of axial and circumferential modes are identified with a particular reference to the fluid-structure system under seismic excitation. Finally, the equations for the dynamic stability analysis of liquid-filled shells are presented.     

Subsensitivity to bronchoprotection against adenosine monophosphate challenge following regular once-daily formoterol

Questions about usual drinking play an important role in the construction of alcohol consumption measures. However, little is known about difficulties in answering these questions for respondents with variability in their drinking patterns. We investigated this in a community sample of 945 drinkers and in a clinical sample of 400 patients treated for alcohol and/or drug problems. Demographic variables were not consistently related to self-reported difficulty in answering, but a diagnosis of current DSM-IV alcohol dependence was significantly related in both samples. In modeling the relationship between alcohol consumption and DSM-IV alcohol dependence, the fit of the model to the data was significantly improved by the addition of a variable indicating respondents' difficulty answering the usual drinking questions. Using this information in the development of alcohol consumption questions may provide more precise estimates of the risk from alcohol consumption to outcomes such as alcohol dependence.     

Reliability and degradation of small molecule-based organiclight-emitting devices (OLEDs)

Studies of degradation mechanisms in small molecule-based organic light-emitting devices (OLEDs) are reviewed. A special emphasis is given to OLEDs based on tris (8-hydroxyquinoline) aluminum (AlQ₃), an emitter and electron transport material used in the majority of OLEDs emitting from the green to the red part of the spectrum. Different strategies used for increasing device stability are addressed and the models proposed to explain experimental observations related to OLED operational stability are discussed. Although none of the presently proposed models can explain all experimental observations, the largest body of experimental evidence appears to be consistent with a model based on the instability of cationic AlQ₃ species, produced by the injection of holes into the AlQ₃ electron transport and emitter layer. Other models may be of importance in explaining degradation behavior on different time scales. Models based on redistribution of space charge appear to be responsible for reversible short-term degradation, while a model based on indium migration may be important for degradation on very long time scales     

Parametric study of instantaneous heat transfer based on multidimensional model in direct-injection hydrogen-fueled engine

This paper presents a parametric study on instantaneous heat transfer of a direct-injection hydrogen-fueled engine using a multidimensional model. A simplified single-step mechanism was considered for estimating the reaction rate of hydrogen oxidation. The modified wall-function was used for resolving the near-wall transport. An arbitrary Lagrangian–Eulerian algorithm was adopted for solving the governing equations. Experimental measurements were implemented to verify the developed model. They show that the instantaneous heat-transfer model is sufficiently accurate. The influence of engine speed, equivalence ratio, and the start of injection timing were investigated. The flow fields appeared to have greater size vectors and coarser distribution with an increase of engine speed. A heterogeneous distribution was obtained for an ultra-lean mixture condition (φ ≤ 0.5), which decreased with an increase of equivalence ratio. There was no pronounced influence of the start of injection on the flow field pattern and mixture homogeneity. Thermal field analysis was used to demonstrate trends in the instantaneous heat transfer. It was observed that there was a crucial distinction between the lean and ultra-lean mixtures as well as the engine speed. Furthermore, a non-uniform behavior was found for the impact of the equivalence ratio on temperature distribution. It is clear that the developed models are powerful tools for estimating the heat transfer of the hydrogen-fueled engine. The developed predictive correlation is highly accurate in predicting the heat transfer of the hydrogen-fueled engine, focusing on the equivalence ratio as a governing variable.