Plasma polymer coated surfaces for serum-free culture of limbal epithelium for ocular surface disease

The potential use of plasma polymer coatings as substrates for serum-free expansion of limbal epithelial cells was investigated. Preliminary studies using a human corneal epithelial cell line showed that acrylic acid-coated surfaces performed better than allyl amine and allyl alcohol coated surfaces in terms of cell metabolic activity and confluence as assessed using the MTT assay. Subsequently, the proliferation and maturity of primary human limbal epithelial cells in co-culture with growth arrested 3T3 fibroblasts on a range of acrylic acid plasma coated surfaces, octadiene plasma coated surfaces and tissue culture plastic was investigated using MTT and cytokeratin 3 immunostaining. The cells performed better in the presence of serum on all surfaces. However, the acrylic acid coated surfaces successfully sustained a serum-free fibroblast/epithelial cell co-culture. The metabolic activity of the epithelial cells was superior on the acrylic acid coated surfaces than on tissue culture plastic in serum-free conditions and their levels of differentiation were not significantly higher than in the presence of serum. These results suggest that these surfaces can be used successfully for the serum-free expansion of human limbal epithelial cells.     

Closed-loop, multiobjective optimization of two-dimensional gas chromatography/mass spectrometry for serum metabolomics

Metabolomics seeks to measure potentially all the metabolites in a biological sample, and consequently, we need to develop and optimize methods to increase significantly the number of metabolites we can detect. We extended the closed-loop (iterative, automated) optimization system that we had previously developed for one-dimensional GC-TOF-MS (O'Hagan, S.; Dunn, W. B.; Brown, M.; Knowles, J. D.; Kell, D. B. Anal. Chem. 2005, 77, 290-303) to comprehensive two-dimensional (GCxGC) chromatography. The heuristic approach used was a multiobjective version of the efficient global optimization algorithm. In just 300 automated runs, we improved the number of metabolites observable relative to those in 1D GC by some 3-fold. The optimized conditions allowed for the detection of over 4000 raw peaks, of which some 1800 were considered to be real metabolite peaks and not impurities or peaks with a signal/noise ratio of less than 5. A variety of computational methods served to explain the basis for the improvement. This closed-loop optimization strategy is a generic and powerful approach for the optimization of any analytical instrumentation.     

Illumination system for wire bonding inspection

A novel lighting system was devised for 3D defect inspection in the wire bonding process. Gold wires of 20 microm in diameter were bonded to connect the integrated circuit (IC) chip with the substrate. Bonding wire defects can be classified as 2D type and 3D type. The 2D-type defects include missed, shifted, or shorted wires. These defects can be inspected from a 2D top-view image of the wire. The 3D-type bonding wire defects are sagging wires, and are difficult to inspect from a 2D top-view image. A structured lighting system was designed and developed to facilitate all 2D-type and 3D-type defect inspection. The devised lighting system can be programmed to turn the structured LEDs on or off independently. Experiments show that the devised illumination system is effective for wire bonding inspection and will be valuable for further applications.     

Adaptive beam shaping by controlled thermal lensing in optical elements

We describe an adaptive optical system for use as a tunable focusing element. The system provides adaptive beam shaping via controlled thermal lensing in the optical elements. The system is agile, remotely controllable, touch free, and vacuum compatible; it offers a wide dynamic range, aberration-free focal length tuning, and can provide both positive and negative lensing effects. Focusing is obtained through dynamic heating of an optical element by an external pump beam. The system is especially suitable for use in interferometric gravitational wave interferometers employing high laser power, allowing for in situ control of the laser modal properties and compensation for thermal lensing of the primary laser. Using CO(2) laser heating of fused-silica substrates, we demonstrate a focal length variable from infinity to 4.0 m, with a slope of 0.082 diopter/W of absorbed heat. For on-axis operation, no higher-order modes are introduced by the adaptive optical element. Theoretical modeling of the induced optical path change and predicted thermal lens agrees well with measurement.     

Ultrasonic extraction and field-portable anodic stripping voltammetric measurement of lead in dust wipe samples

Dust wipe samples were subjected to ultrasonic extraction (UE) in diluted nitric acid, and then analyzed for lead content using field-portable anodic stripping voltammetry (ASV). Recoveries of lead were determined from wipe materials which were spiked with certified reference materials (CRMs) containing known quantities of lead. Four different wipe materials and four different CRMs were tested, with and without filtration of aliquots of sample extract through 0.45 microm hydrophilic polytetrafluoroethylene filters. The CRMs consisted of paint, soil, particulate, and dust matrices. Wipe materials were chosen from those which have been found to meet the performance aspects of an ASTM standard specification. UE/ASV experiments were carried out in accordance with newly published ASTM procedures for on-site extraction and electroanalysis. Recoveries were found to vary for different wipe materials and CRMs. For several CRMs, quantitative (80--120%) recoveries for UE/ASV were observed for one wipe material whether filtration was used or not, while other wipe materials required filtration for quantitative recovery. In the case of one wipe material which contained detergents, quantitative recoveries could not be achieved whether filtration was used or not. The total analysis time for a sample set of 6--12 samples was 60--90 min, including extraction time and sample manipulation. The results of this work have provided information on the choice of wipe materials that can be used for quantitative lead measurements by UE/ASV in materials that are representative of sources of lead in surface dust.     

Temperature-dependent optical constants of water ice in the near infrared: new results and critical review of the available measurements

The optical constants of water ice have been determined in the near infrared from 4000 to 7000 cm(-1). Polycrystalline ice films with thickness as great as ~1164 mum were formed by condensation of water vapor on a cold silicon substrate at temperatures of 166, 176, 186, and 196 K. The transmission of light through the ice films was measured during their growth from 0 to 1164 mum over the frequency range of approximately 500-7000 cm(-1). The optical constants were extracted by means of simultaneously fitting the calculated transmission spectra of films of varying thickness to their respective measured transmission spectra with an iterative Kramers-Kronig technique. Equations are presented to account for reflection losses at the interfaces when the sample is held in a cell. These equations are used to reanalyze the transmission spectrum of water ice (358-mum sample at 247 K) recorded by Ockman in 1957 [Philos. Mag. Suppl. 7, 199 (1958)]. Our imaginary indices for water ice are compared with those of Gosse et al. [Appl. Opt. 34, 6582 (1995)], Kou et al. [Appl. Opt. 32, 3531 (1993)], Grundy and Schmitt [J. Geophys. Res. 103, 25809 (1998)], and Warren [Appl. Opt. 23, 1206 (1984)], and with the new indices from Ockman's spectrum. The temperature dependence in the imaginary index of refraction observed by us between 166 and 196 K and that between our data at 196 K and the data of Gosse et al. at 250 K are compared with that predicted by the model of Grundy and Schmitt. On the basis of this comparison a linear interpolation of the imaginary indices of refraction between 196 and 250 K is proposed. We believe that the accuracy of this interpolation is better than 20%.     

Bayesian recognition of local 3-d shape by approximating image intensity functions with quadric polynomials

The recognition in image data of viewed patches of spheres, cylinders, and planes in the 3-D world is discussed as a first step to complex object recognition or complex object location and orientation estimation. Accordingly, an image is partitioned into small square windows, each of which is a view of a piece of a sphere, or of a cylinder, or of a plane. Windows are processed in parallel for recognition of content. New concepts and techniques include approximations of the image within a window by 2-D quadric polynomials where each approximation is constrained by one of the hypotheses that the 3-D surface shape seen is either planar, cylindrical, or spherical; a recognizer based upon these approximations to determine whether the object patch viewed is a piece of a sphere, or a piece of a cylinder, or a piece of a plane; lowpass filtering of the image by the approximation. The shape recognition is computationally simple, and for large windows is approximately Bayesian minimum-probability-of-error recognition. These classifications are useful for many purposes. One such purpose is to enable a following processor to use an appropriate estimator to estimate shape, and orientation and location parameters for the 3-D surface seen within a window.     

Evaluating Multimembership Classifiers: A Methodology and Application to the MEDAS Diagnostic System

Performance evaluation measures for multimembership classifiers are presented and applied in a retrospective study on the diagnostic performance of the MEDAS (Medical Emergency Decision Assistance System) system. Admission and discharge diagnoses for 122 patients with one or more of 26 distinct disorders in five major disorder categories were gathered. The average number of disorders per patient was 2 with 36 (29.5 percent) patients having 3 or more disorders simultaneously. The features (symptoms, signs, and laboratory data) available at admission were entered into a multimembership Bayesian pattern recognition algorithm which permits for diagnosis of multiple disorders. When the top five computer-ranked diagnoses were considered, all of the correct diagnoses for 86.1 percent of the patients were displayed by the fifth position. In 71.6 percent of these cases, no false diagnosis preceded any correct diagnosis. In ten cases a discharge diagnosis which was suggested by the available findings was omitted by the admitting physician. In six of these ten cases, the overlooked diagnoses appeared at the computer ranked list above all false diagnoses. Considering the urgency of diagnosis in the Emergency Department, the high uncertainty involved due to the limited availability of data, and the high frequency with which multiple disorders coexist, this limited study encourages our confidence in the MEDAS knowledge base and algorithm as a useful diagnostic support tool.     

Effect of handle height on lower-back loading in cart pushing and pulling

This paper presents results of a study conducted to estimate lower back loadings in cart pushing and pulling. Experiments were conducted in the laboratory using a cart. Six subjects with different weights (ranging from 50 to 80 kg) were tested for three different pushing and pulling forces (98, 196 and 294 newtons), three different heights of exertion (660, 1090 and 1520 mm high) and two different moving speeds (1.8 and 3.6 km/h). It was found that, in general, pushing a cart results in lesser lower-back loading than pulling. Subject body weight affected the lower-back loadings more significantly in pulling (50% increase as body weight increased from 50 kg to 80 kg) than in pushing (25% increase). Handle height of 1090 mm was found to be better than other handle heights in pushing while 1520 mm handle height was better for pulling in reducing lower-back loadings.