High-throughput nanohole array based system to monitor multiple binding events in real time

We have developed an integrated label-free, real-time sensing system that is able to monitor multiple biomolecular binding events based on the changes in the intensity of extraordinary optical transmission (EOT) through nanohole arrays. The core of the system is a sensing chip containing multiple nanohole arrays embedded within an optically thick gold film, where each array functions as an independent sensor. Each array is a square array containing 10 x 10 nanoholes (150 nm in diameter), occupying a total area of 3.3 mum x 3.3 mum. The integrated system includes a laser light source, a temperature-regulated flow cell encasing the sensing chip, motorized optics, and a charge-coupled detector (CCD) camera. For demonstration purposes, sensing chips containing 25 nanohole arrays were studied for their use in multiplexed detection, although the sensing chip could be easily populated to contain up to 20 164 nanohole arrays within its 0.64 cm2 sensing area. Using this system, we successfully recorded 25 separate binding curves between glutathione S-transferase (GST) and anti-GST simultaneously in real time with good sensitivity. The system responds to binding events in a concentration-dependent manner, showing a sharp linear response to anti-GST at concentrations ranging from 13 to 290 nM. The EOT intensity-based approach also enables the system to monitor multiple bindings simultaneously and continuously, offering a temporal resolution on milliseconds scale that is decided only by the camera speed and exposure time. The small footprint of the sensing arrays combined with the EOT intensity-based approach enables the system to resolve binding events that occurred on nanohole sensing arrays spaced 96 mum apart, with a reasonable prediction of resolving binding events spaced 56 mum apart. This work represents a new direction that implements nanohole arrays and EOT intensity to meet high-throughput, spatial and temporal resolution, and sensitivity requirements in drug discovery and proteomics studies.     

Fluorescent resonance energy transfer based detection of biological contaminants through hybrid quantum dot-quencher interactions

A nanoscale sensor employing fluorescent resonance energy transfer interactions between fluorescent quantum dots (QDs) and organic quencher molecules can be used for the multiplexed detection of biological antigens in solution. Detection occurs when the antigens to be detected displace quencher-labelled inactivated (or dead) antigens of the same type attached to QD-antibody complexes through equilibrium reactions. This unquenches the QDs, allowing detection to take place through the observation of photoluminescence in solution or through the fluorescence imaging of unquenched QD complexes trapped on filter surfaces. Multiplexing can be accomplished by using several different sizes of QDs, with each size QD labelled with an antibody for a different antigen, providing the ability to detect several types of antigens or biological contaminants simultaneously in near real-time with high specificity and sensitivity.     

A multiresolution representation for massive meshes

We present a new external memory multiresolution surface representation for massive polygonal meshes. Previous methods for building such data structures have relied on resampled surface data or employed memory intensive construction algorithms that do not scale well. Our proposed representation combines efficient access to sampled surface data with access to the original surface. The construction algorithm for the surface representation exhibits memory requirements that are insensitive to the size of the input mesh, allowing it to process meshes containing hundreds of millions of polygons. The multiresolution nature of the surface representation has allowed us to develop efficient algorithms for view-dependent rendering, approximate collision detection, and adaptive simplification of massive meshes. The empirical performance of these algorithms demonstrates that the underlying data structure is a powerful and flexible tool for operating on massive geometric data.     

Relation of effort-performance expectancy to performance in goal-setting experiments.

Explored the relationship between effort–performance expectancy and task performance in goal-setting research. A review indicates that the literature in this area is highly inadequate, failing to distinguish between the expectancy–performance relation within as compared to between assigned goal conditions. Data from 2 recent experiments by the present author (see PA, Vols 68:360 and 69:11929) were reanalyzed through hierarchical multiple regression of performance on both goal level and expectancy, measured as a subjective probability of success. Ss in each experiment (86 and 58 undergraduates, respectively) performed repeated trials of a creativity task under different assigned goals. The reanalyses suggest that both goal levels and expectancy made independent contributions to variance in performance. Potential strategies for increasing performance by raising both goal levels and expectancies simultaneously are briefly discussed. New ways of conceptualizing expectancy and valence in goal-setting research are presented. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Analysis of experimental constraints and variables for time resolved detection of Fourier transform electrochemical impedance spectra

By using the Fourier transform (FT) technique, it is possible to perform electrochemical impedance spectroscopy in real time during the occurrence of DC voltage controlled surface reactions. The data obtained in this approach, a series of Nyquist plots as functions of DC control variables, can provide a wealth of time resolved information about surface kinetics. We discuss in detail the theoretical and experimental considerations for such time resolved experiments. We focus primarily on the constraints and criteria of measurements in the context of new data acquisition electronics that became available during the last few years. We also present sample experimental results for a gold electrode.     

New Ethylene Copolymers for Automotive Carpet Backing

The backsizing resin most commonly used in automotive carpet today is powdered, low-density polyethylene. Its primary function is to stiffen the carpet, but it also provides other very important properties. It allows the carpet to be thermoformable and also acts as an adhesive, holding the carpet together and bonding the jute underpad to the carpet as the carpet is reheated and molded.     

Calibration of dielectric constant measurements to improve the detection of cloud and clear points in solution crystallization

Metastable zone width, which can be approximated as the gap between the loci of cloud and clear points is an important control parameter for successful operations of solution crystallization processes. This study attempts to improve the accuracy of cloud point determination in paracetamol-ethanol solution using dielectric constant measurements and a special calibration technique. A suitable calibration model based on logarithm-polynomial expansion is developed using adjusted R² and Akaike Information Criterion as model selection guides. The model, which decouples the effects of temperature and solute concentration on solution dielectric constant, is utilized to transform the dielectric constant profile into a solute concentration profile. The results show that the cloud points determined from the solute concentration profile are more accurate than those determined directly from the dielectric constant profile. The former are shown to be in good agreement with those obtained from the turbidity measurements, which are used as benchmarks in this study. Consequently, a more accurate metastable zone width could also be obtained using this calibration technique.     

Impact of Time in Prison and Security Level on Inmates' Sexual Attitude, Behavior, and Identity.

The aim of the present study was to develop an understanding of changes in inmates' sexual identity and the role these changes play in inmates' sexual attitudes and behaviors while incarcerated. Participants in this study consisted of 185 inmates from minimum and maximum security correctional facilities in a midwestern state. Results revealed that the higher the security level was and the longer inmates spent in a correctional facility, the greater was the probability that inmates would begin to endorse some preference for same-sex sexual behavior. This is in contrast to the finding that inmates less readily changed their sexual identity from heterosexual to homosexual regardless of the security level or the length of time spent in prison. Furthermore, inmates generally reported engaging in consensual same-sex sexual activities for reasons that are consistent with those of nonincarcerated persons (love and pleasure). Implications and future studies are also discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Biofouling affinity of membrane surfaces under quiescent conditions

Biofouling affinity of four thin film membranes was evaluated under quiescent conditions by exposing the membrane to the effluent from a membrane bioreactor. Coupons of the thin film membranes were left for 5 days in the bioreactor effluent which was filtered through a 0.2 micron filter. The surface morphologies of the membranes before and after the exposure were evaluated by atomic force microscopy (AFM). All membranes showed significant amounts of deposits after the exposure. The easily disturbed nature of the deposits on the polyamide membrane indicated that these deposits were either entrapped within the surface crevices or loosely attached on the membrane. The extent of surface coverage and uniform appearance of the deposits on the polysulfone membrane were indicative of molecular adhesion by functional groups on the membrane surface. Based on the wetting angle measurements, all clean membranes exhibited hydrophilic characteristics. After exposure to the bioreactor effluent, the membranes exhibited complete wetting characteristics. The use of AFM image analysis technique provided insight for the morphological changes and substrate accumulation patterns on membrane surfaces.