5.1. Detection Formats 475 5.2. Food Quality and Safety Analysis 477 5.2.1. Pathogens 477 5.2.2. Toxins 479 5.2.3. Veterinary Drugs 479 5.2.4. Vitamins 480 5.2.5. Hormones 480 5.2.6. Diagnostic Antibodies 480 5.2.7. Allergens 481 5.2.8. Proteins 481 5.2.9. Chemical Contaminants 481 5.3. Medical Diagnostics 481 5.3.1. Cancer Markers 481 5.3.2. Antibodies against Viral Pathogens 482 5.3.3. Drugs and Drug-Induced Antibodies 483 5.3.4. Hormones 483 5.3.5. Allergy Markers 483 5.3.6. Heart Attack Markers 484 5.3.7. Other Molecular Biomarkers 484 5.4. Environmental Monitoring 484 5.4.1. Pesticides 484 5.4.2. 2,4,6-Trinitrotoluene (TNT) 485 5.4.3. Aromatic Hydrocarbons 485 5.4.4. Heavy Metals 485 5.4.5. Phenols 485 5.4.6. Polychlorinated Biphenyls 487 5.4.7. Dioxins 487 5.5. Summary 488 6. Conclusions 489 7. Abbreviations 489 8. Acknowledgment 489 9. References 489

Surface Plasmon Resonance Sensors for Detection of Chemical and Biological Species

A fast-Fourier-transform method of topography and interferometry is proposed. By computer processing of a noncontour type of fringe pattern, automatic discrimination is achieved between elevation and depression of the object or wave-front form, which has not been possible by the fringe-contour-generation techniques. The method has advantages over moire topography and conventional fringe-contour interferometry in both accuracy and sensitivity. Unlike fringe-scanning techniques, the method is easy to apply because it uses no moving components.

Fourier-transform method of fringe-pattern analysis for computer-based topography and interferometry

Macroscopic thin liquid films are entities that are important in biophysics, physics, and engineering, as well as in natural settings. They can be composed of common liquids such as water or oil, rheologically complex materials such as polymers solutions or melts, or complex mixtures of phases or components. When the films are subjected to the action of various mechanical, thermal, or structural factors, they display interesting dynamic phenomena such as wave propagation, wave steepening, and development of chaotic responses. Such films can display rupture phenomena creating holes, spreading of fronts, and the development of fingers. In this review a unified mathematical theory is presented that takes advantage of the disparity of the length scales and is based on the asymptotic procedure of reduction of the full set of governing equations and boundary conditions to a simplified, highly nonlinear, evolution equation or to a set of equations. As a result of this long-wave theory, a mathematical system is obtained that does not have the mathematical complexity of the original free-boundary problem but does preserve many of the important features of its physics. The basics of the long-wave theory are explained. If, in addition, the Reynolds number of the flow is not too large, the analogy with Reynolds's theory of lubrication can be drawn. A general nonlinear evolution equation or equations are then derived and various particular cases are considered. Each case contains a discussion of the linear stability properties of the base-state solutions and of the nonlinear spatiotemporal evolution of the interface (and other scalar variables, such as temperature or solute concentration). The cases reducing to a single highly nonlinear evolution equation are first examined. These include: (a) films with constant interfacial shear stress and constant surface tension, (b) films with constant surface tension and gravity only, (c) films with van der Waals (long-range molecular) forces and constant surface tension only, (d) films with thermocapillarity, surface tension, and body force only, (e) films with temperature-dependent physical properties, (f) evaporating/condensing films, (g) films on a thick substrate, (h) films on a horizontal cylinder, and (i) films on a rotating disc. The dynamics of the films with a spatial dependence of the base-state solution are then studied. These include the examples of nonuniform temperature or heat flux at liquid-solid boundaries. Problems which reduce to a set of nonlinear evolution equations are considered next. Those include (a) the dynamics of free liquid films, (b) bounded films with interfacial viscosity, and (c) dynamics of soluble and insoluble surfactants in bounded and free films. The spreading of drops on a solid surface and moving contact lines, including effects of heat and mass transport and van der Waals attractions, are then addressed. Several related topics such as falling films and sheets and Hele-Shaw flows are also briefly discussed. The results discussed give motivation for the development of careful experiments which can be used to test the theories and exhibit new phenomena.

Long-scale evolution of thin liquid films

Wetting phenomena are ubiquitous in nature and technology. A solid substrate exposed to the environment is almost invariably covered by a layer of fluid material. In this review, the surface forces that lead to wetting are considered, and the equilibrium surface coverage of a substrate in contact with a drop of liquid. Depending on the nature of the surface forces involved, different scenarios for wetting phase transitions are possible; recent progress allows us to relate the critical exponents directly to the nature of the surface forces which lead to the different wetting scenarios. Thermal fluctuation effects, which can be greatly enhanced for wetting of geometrically or chemically structured substrates, and are much stronger in colloidal suspensions, modify the adsorption singularities. Macroscopic descriptions and microscopic theories have been developed to understand and predict wetting behavior relevant to microfluidics and nanofluidics applications. Then the dynamics of wetting is examined. A drop, placed on a substrate which it wets, spreads out to form a film. Conversely, a nonwetted substrate previously covered by a film dewets upon an appropriate change of system parameters. The hydrodynamics of both wetting and dewetting is influenced by the presence of the three-phase contact line separating "wet" regions from those that are either dry or covered by a microscopic film only. Recent theoretical, experimental, and numerical progress in the description of moving contact line dynamics are reviewed, and its relation to the thermodynamics of wetting is explored. In addition, recent progress on rough surfaces is surveyed. The anchoring of contact lines and contact angle hysteresis are explored resulting from surface inhomogeneities. Further, new ways to mold wetting characteristics according to technological constraints are discussed, for example, the use of patterned surfaces, surfactants, or complex fluids.

/pdf/wetting-and-spreading-56ditqbfmj.pdf

Wetting and Spreading

An overview of the recent developments in the field of cylindrical vector beams is
provided. As one class of spatially variant polarization, cylindrical vector beams
are the axially symmetric beam solution to the full vector electromagnetic wave
equation. These beams can be generated via different active and passive methods.
Techniques for manipulating these beams while maintaining the polarization symmetry
have also been developed. Their special polarization symmetry gives rise to unique
high-numerical-aperture focusing properties that find important applications in
nanoscale optical imaging and manipulation. The prospects for cylindrical vector
beams and their applications in other fields are also briefly discussed.

Cylindrical vector beams: from mathematical concepts to applications

A method of analyzing an optical image of a scene to determine the spectral intensity of each pixel of the scene, which includes collecting incident light from the scene; (b) passing the light through an interferometer which outputs modulated light corresponding to a predetermined set of linear combinations of the spectral intensity of the light emitted from each pixel; focusing the light outputted from the interferometer on a detector array; and processing the output of the detector array to determine the spectral intensity of each pixel thereof. If the interferometer is of the moving type scanning in one dimension is required where the detector array is one dimensional, and no scanning when the detector array is two-dimensional. If the interferometer is of the non-moving type scanning is required in one dimension when the detector array is two-dimensional, and in two dimensions when the detector array is one-dimensional.

Method for simultaneously measuring the spectral intensity as a function of wavelength of all the pixels of a two dimensional scene

A Fourier transform multipixel spectroscopy system was set up and applied to fluorescence microscopy of single living cells. Continuous fluorescence spectra for all pixels of the cell image were recorded simultaneously by the system. Multiple frames of data were first acquired and stored as a set of interferograms for each pixel of the image; they were then Fourier transformed and used as a spatially organized set of fluorescence spectra. Practical spectral resolution of 5 nm was achieved, typically, for 104 pixels in a single cell. The net result was I(xy,λ), the fluorescence intensity (I) for each pixel of the image (xy), as function of wavelength (λ). The present study demonstrates that multipixel spectroscopy can reveal dynamic processes of the food-digestive cycle in the unicellular Paramecium vulgaris fed with algae. Spectral variability of fluorescence intensity at different cytoplasmic sites pinpointed the location of cellular deposits of chlorophyll (630 nm) and of pheophytin (695 nm), a digestive product of the chlorophyll. Localization of compartmental spectral changes was achieved using a ‘similarity mapping’ algorithm, followed by enhanced image construction. Similarity mapping based on the fluorescence spectrum of native chlorophyll revealed a highlighted image of the cell cytopharynx structure where algae were ingested. Phagolysosomes, migrating vacuoles and the cytoproct, each containing different ratios of pheophytin, were similarly imaged.

Fourier transform multipixel spectroscopy for quantitative cytology

We present a promising optical system and technique for detection, imaging, and visualization of minimal changes, of the order of 10−6 in refractive index, in the near field. The system is based on phase imaging of excited surface plasmons in a conducting layer in contact with a sample. This technique is shown here to be sensitive enough to image the flow of helium and argon gas in a nitrogen atmosphere. Its application to biological and chemical research is suggested.

Surface plasmon resonance phase imaging

Optical Physics: Frontmatter

A new optical technique for measuring and visualization of local changes of the order of 10−6 in refractive index in a field of view, based on non-linear phase amplification by surface plasmon resonance is presented. Its application to biological and chemical local bio-sensing and imaging is suggested.

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Method for simultaneously measuring the spectral intensity as a function of wavelength of all the pixels of a two dimensional scene

Fourier transform multipixel spectroscopy for quantitative cytology

Surface plasmon resonance phase imaging

Optical Physics: Frontmatter

Surface plasmon resonance phase imaging