Theory for solvent, momentum, and energy transfer between a surfactant solution and a vapor atmosphere

We develop a complete set of equations governing the evolution of a sharp interface separating a volatile-solvent/nonvolatile-surfactant solution from a vapor atmosphere. In addition to a sorption isotherm equation and the conventional balances for mass, linear momentum, and energy, these equations include a counterpart of the Hertz???Knudsen???Langmuir equation familiar from conventional theories of evaporation-condensation. This additional equation arises from a consideration of configurational forces within a thermodynamical framework. While the notion of configurational forces is well-developed and understood for the description of materials, like crystalline solids, that possess natural reference configurations, very little has been done regarding their role in materials, such as viscous fluids, that do not possess preferred reference states. We therefore provide a comprehensive discussion of configurational forces, the balance of configurational momentum, and configurational thermodynamics that does not require a choice of reference configuration. The general evolution equations arising from our theory account for the thermodynamic structure of the solution and the interface and for sources of dissipation related to the transport of surfactant, momentum, and heat in the solution, the transport of surfactant and momentum within the interface, and the transport of solute, momentum, kinetic energy, and heat across the interface. Due to the complexity of these equations, we provide approximate equations which we compare to relations that appear in the literature.published or submitted for publicationis peer reviewe

Microscopic Investigation of Vortex Breakdown in a Dividing T-Junction Flow

3D-printed microfluidic devices offer new ways to study fluid dynamics. We present the first clear visualization of vortex breakdown in a dividing T-junction flow. By individual control of the inflow and two outflows, we decouple the effects of swirl and rate of vorticity decay. We show that even slight outflow imbalances can greatly alter the structure of vortex breakdown, by creating a net pressure difference across the junction. Our results are summarized in a dimensionless phase diagram, which will guide the use of vortex breakdown in T-junctions to achieve specific flow manipulation.Comment: 5 pages, 5 figure

Can Emerging Markets Offer Diversification Benefits to Canadian Investors During Credit Crisis?

This paper examines whether emerging markets offer benefits to a Canadian portfolio when it is needed most during a credit crisis. The study considers the relationship of the monthly data of ten emerging market indices (EM) and its weighted index with Toronto Stock Exchange Composite Index (TSX) through out 1998 to August 2007. We add S&P500 and MSCI EAFE to represent a diversified developed market portfolio. While the findings indicate most individual emerging market and its weighted index do not add values to a Canadian portfolio when credit risk is tight, China stands out differently. China adds significant diversification benefits to the developed market portfolio when credit risk is tight. When examining the subprime credit crunch in summer 2007, the results are consistent with the sample period, that is, Canadian investors benefit from diversifying in China during credit crisis

Optimized Immobilization of Biomolecules on Nonspherical Gold Nanostructures for Efficient Localized Surface Plasmon Resonance Biosensing

Plasmonic biosensing techniques employ metal nanostructures, commonly gold (Au), often with biomolecules attached to their surfaces either directly or via other linkers. Various surface chemistry methods based on dispersion and covalent interactions are used to attach biomolecules to Au. As a result, when immobilizing a molecule on a metal surface, quantitative estimates of binding efficiency and stability of these surface chemistry methods are needed. Most prior work to compare such methods deals with bulk/thin film configurations or spherical nanoparticles, and very little is known about immobilization of biomolecules on plasmonic nanostructures of different shapes. Besides, due to rapid advancement of modern nanofabrication techniques, there is a growing need to determine an efficient surface chemistry method for immobilization of biomolecules on nonspherical plasmonic nanostructures. Previous comparison of immobilization methods on spherical Au nanoparticles has shown that physical adsorption resulted in the highest concentration of immobilized antibodies. In our work, we conducted a similar study and compared four representative Au surface functionalization methods as well as estimated how efficient these methods are at attaching biomolecules to nonspherical plasmonic Au nanostructures. We estimated the concentration of immobilized antibody that is specific to human C-reactive protein (anti-hCRP) by measuring the localized surface plasmon resonance (LSPR) shifts after exposing the surface of Au nanostructures to the antibody. Our results differ from the previously reported ones since the highest concentration of anti-hCRP was immobilized using 11-mercaptoundecanoic acid (MUA) chemistry. We demonstrated that immobilized antibodies retained their stability and specificity toward hCRP throughout the immunoassay when diluted hCRP or hCRP-spiked human serum samples were used. These findings have important implications for the fields of biosensing and diagnostics that employ nonspherical plasmonic nanostructures since an overall performance of these devices depends on efficient biomolecule immobilization

Lutein and the Aging Eye

Lutein is a carotenoid highly concentrated in the macula of the retina. Lutein cannot be synthesized and must be supplied in the diet, for example, dark green leafy vegetable and egg yolk. Lutein is believed to absorb blue light, leading to the protection of retina from light-related damage. It can also protect the retina against oxidative stress and inflammation. In fact, dietary and supplementary lutein have been shown to be associated with possible reduced risk of age-related macular degeneration, a leading cause of elderly blindness, attributed largely to lutein’s antioxidant properties. Lutein is also beneficial as a nutritional supplement in preventing diabetic retinopathy. Moreover, lutein is very safe and widely used. In this chapter, we will discuss the basic chemistry of lutein; its uptake, transport, distribution, and functions in the normal eye. Lastly, the effects of lutein in age-related eye diseases will be summarized

Protecting the Aging Retina

Aging retina, notably the aging macula, is prone to develop degenerative diseases, such as age-related macular degeneration (AMD), the leading cause of visual loss in individuals aged 65 or above in developed countries. However, current treatments are very limited. Since degeneration, dysfunction, and death of retinal neurons are demonstrated in the pathogenesis of AMD, neuroprotective strategies could serve as a possible way to treat AMD. In this chapter, we will briefly introduce risk factors, pathophysiology, affected neurons, classification, clinical manifestation, and current treatments of AMD. Finally, neuroprotection in both AMD animal models and patients will be discussed

Detecting Escherichia coli Biofilm Development Stages on Gold and Titanium by Quartz Crystal Microbalance

Bacterial biofilms are responsible for persistent infections and biofouling, raising serious concerns in both medical and industrial processes. These motivations underpin the need to develop methodologies to study the complex biological structures of biofilms and prevent their formation on medical implants, tools, and industrial apparatuses. Here, we report the detailed comparison of Escherichia coli biofilm development stages (adhesion, maturation, and dispersion) on gold and titanium surfaces by monitoring the changes in both frequency and dissipation of a quartz crystal microbalance (QCM) device, a cheap and reliable microgravimetric sensor which allows the real-time and label-free characterization of various stages of biofilm development. Although gold is the most common electrode material used for QCM sensors, the titanium electrode is also readily available for QCM sensors; thus, QCM sensors with different metal electrodes serve as a simple platform to probe how pathogens interact with different metal substrates. The QCM outcomes are further confirmed by atomic force microscopy and crystal violet staining, thus validating the effectiveness of this surface sensitive sensor for microbial biofilm research. Moreover, because QCM technology can easily modify the substrate types and coatings, QCM sensors also provide well-controlled experimental conditions to study antimicrobial surface treatments and eradication procedures, even on mature biofilms

Air Plasma-Enhanced Covalent Functionalization of Poly(methyl methacrylate): High-Throughput Protein Immobilization for Miniaturized Bioassays

Miniaturized systems, such as integrated microarray and microfluidic devices, are constantly being developed to satisfy the growing demand for sensitive and high-throughput biochemical screening platforms. Owing to its recyclability, and robust mechanical and optical properties, poly(methyl methacrylate) (PMMA) has become the most sought after material for the large-scale fabrication of these platforms. However, the chemical inertness of PMMA entails the use of complex chemical surface treatments for covalent immobilization of proteins. In addition to being hazardous and incompatible for large-scale operations, conventional biofunctionalization strategies pose high risks of compromising the biomolecular conformations, as well as the stability of PMMA. By exploiting radio frequency (RF) air plasma and standard 1-ethyl-3-(3-(dimethylamino)propyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) chemistry in tandem, we demonstrate a simple yet scalable PMMA functionalization strategy for covalent immobilization (chemisorption) of proteins, such as green fluorescent protein (GFP), while preserving the structural integrities of the proteins and PMMA. The surface density of chemisorbed GFP is shown to be highly dependent on the air plasma energy, initial GFP concentration, and buffer pH, where a maximum GFP surface density of 4 × 10–7 mol/m2 is obtained, when chemisorbed on EDC–NHS-activated PMMA exposed to 27 kJ of air plasma, at pH 7.4. Furthermore, antibody-binding studies validate the preserved biofunctionality of the chemisorbed GFP molecules. Finally, the coupled air plasma and EDC–NHS PMMA biofunctionalization strategy is used to fabricate microfluidic antibody assay devices to detect clinically significant concentrations of Chlamydia trachomatis specific antibodies. By coupling our scalable and tailored air plasma-enhanced PMMA biofunctionalization strategy with microfluidics, we elucidate the potential of fabricating sensitive, reproducible, and sustainable high-throughput protein screening systems, without the need for harsh chemicals and complex instrumentation

Coarse-to-Fine Annotation Enrichment for Semantic Segmentation Learning

Rich high-quality annotated data is critical for semantic segmentation learning, yet acquiring dense and pixel-wise ground-truth is both labor- and time-consuming. Coarse annotations (e.g., scribbles, coarse polygons) offer an economical alternative, with which training phase could hardly generate satisfactory performance unfortunately. In order to generate high-quality annotated data with a low time cost for accurate segmentation, in this paper, we propose a novel annotation enrichment strategy, which expands existing coarse annotations of training data to a finer scale. Extensive experiments on the Cityscapes and PASCAL VOC 2012 benchmarks have shown that the neural networks trained with the enriched annotations from our framework yield a significant improvement over that trained with the original coarse labels. It is highly competitive to the performance obtained by using human annotated dense annotations. The proposed method also outperforms among other state-of-the-art weakly-supervised segmentation methods.Comment: CIKM 2018 International Conference on Information and Knowledge Managemen