Thermodynamics of flat thin liquid films

The two main themes of this study aim to resolve conflicting results in the literature regarding the thermodynamics of flat (uniform thickness) thin liquid films. One of the themes concerns the augmented Young equation, which is a condition for mechanical equilibrium. Two different expressions for the augmented Young equation have appeared in the literature. It is shown that under certain assumptions, the two expressions can be made equivalent. The second main theme addresses thermodynamic functions describing systems with non‐pressure‐volume (non‐PV) work. In thin liquid films, the non‐PV work is the film tension work. Two different expressions that relate the film's Gibbs energy to its internal energy have appeared in the literature. This ambiguity is resolved by showing that only one of the Gibbs energies can be used to determine the equilibrium state via energy minimization. The analysis can be readily generalized to systems with other types of non‐PV work. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3104–3115, 2015     

Evaluation of fly ash- and slag-based geopolymers for the improvement of a soft marine clay by deep soil mixing

The use of deep soil mixing (DSM) in ground-improvement projects, for structures subjected to low to medium loads, has increased over the past decade due to its convenient and practical implementation and its economic advantages. Traditionally, Portland cement and lime have been the most popular binders for DSM applications. However, the ground-improvement industry has been keen to explore environmentally friendly alternatives with low carbon dioxide emission. The aim of this research is to investigate the use of two stockpiled industrial waste by-products, namely, fly ash (FA) and slag (S), as alternative green binders in ground-improvement projects that would reduce the carbon footprint of these projects. In this research, combinations of FA and S, activated by a liquid alkaline activator (L), were evaluated for the ground improvement of a soft marine clay, namely, Coode Island Silt (CIS). The performance of the FA?+?S geopolymers was compared with that of traditional cement and lime control binders. The soil moisture content was set at 0.75, 1.0 and 1.25 of the liquid limit (LL) of the soil to replicate the field conditions. 10, 20 and 30% binders, by dry soil mass, were added to the soil, and the samples were cured for 7 and 28?days. Unconfined compression strength (UCS), flexural beam and scanning electron microscopy (SEM) imaging tests were conducted to evaluate the changes in the engineering behavior and the microstructure of the mixtures. The results indicated that the strength and stiffness of the soft clay were significantly increased by the use of these new FA?+?S binders, which substantiated them as alternatives to traditional cement or lime binders. The optimum binder content was found to be 20%, while CIS?+?5%FA?+?15%S was found to be the optimum mixture. Furthermore, correlations between the UCS and the modulus of elasticity (E₅₀) and between the UCS and the modulus of rupture (R) for the geopolymer mixtures were proposed. They will be valuable to both designers and practitioners of ground-improvement works.     

A constitutive approach for studying concentrated suspensions of rigid fibers in a non ‐ Newtonian Ellis fluid

Abstract

A constitutive model for a semi‐concentrated suspension of rigid fibers in a non‐Newtonian fluid is derived in the present study. This work is extended from a previous work by Dinh and Armstrong which counted rigid fibers suspended in a Newtonian fluid. To investigate the effect of the shear‐dependent suspending fluid on the shear viscosity of suspension, the Ellis fluid is assumed to model such a non‐linear matrix. It is shown that the present derivation, via a cell model, gives an analytic form to calculate the drag coefficient of fibers and to illustrate the influence of material parameters of matrix fluid. The resulting equation gives the bulk stress in terms of an integral over a fourth‐order orientation vector, e, similar to the expression of Doi and Edwards for dense macromolecular fluid. For the purpose of evaluation, the present model attempts to predict the rheological behavior in the inception of flow, steady simple shear flow and stress‐growth experiments.     

Envenoming by Chinese krait (Bungarus multicinctus) and banded krait (B. fasciatus) in Myanmar

A retrospective study of 8 cases of envenoming by Chinese krait (Bungarus multicinctus) and one banded krait (B. fasciatus) in southern Myanmar is reported. Chinese krait bite produced minimal local reactions, except in one person bitten on the lip which resulted in local swelling. Onset of neurotoxic symptoms occurred 2.5-6 h after the bite, and the interval between bite and death ranged from 12-30 h. Three deaths were due to respiratory failure. Four mildly envenomed cases recovered spontaneously without assisted ventilation. One severely envenomed patient recovered after 8 d intensive respiratory care. Cobra (Naja kaouthia) antivenom had no value in reversing neurotoxic symptoms. Anticholinesterase injection given to one patient failed to improve neurotoxic symptoms. The bite of banded krait (B. fasciatus) resulted in neurotoxic envenoming within 2 h after the bite, with minimal local reactions. The victim died of respiratory failure 14 h after the bite.     

Nonuniform Data-Dependent Noise Prediction in Magnetic Recording

In this paper, we report a method for nonuniform data-dependent noise prediction (DDNP), in which the noise predictive filters do not have an identical order (number of taps). To accommodate this new architecture, we implemented a partial decision feedback strategy for branch metric computations of the higher order predictive filters. Theoretical analysis and computer simulations show that our proposed DDNP can achieve a better tradeoff between detection performance and computational complexity compared with the previously reported DDNP     

Reduced serum IgG reactivities with bacteria from dental plaque in HIV-infected persons with periodontitis

Serum samples were obtained from 44 HIV-seropositive (HIV+) and 37 HIV-seronegative (HIV-) persons that were grouped according to periodontal status. Serum IgG and IgA reactivities towards Streptococcus mutans, Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis. Prevotella intermedia, Prevotella nigrescens and Fusobacterium nucleatum were measured by means of ELISA. HIV+ persons with chronic marginal periodontitis showed significantly lower IgG reactivities to the periodontal pathogens A. actinomycetemcomitans, P. gingivalis, P. intermedia and F. nucleatum as compared with their HIV- counterparts (p < 0.05). Specific serum IgA reactivities were similar in the two periodontitis groups, except for P. nigrescens where the HIV+ group with chronic marginal periodontitis had lower values than their systemically healthy counterparts (p < 0.05). The results indicate that HIV infection affects the humoral serum immune responses against bacteria in dental plaque; the depressed antibody responses may contribute to the increased susceptibility for periodontal infections in HIV-infected patients.