Ordered, two-dimensional cadmium selenide (CdSe) arrays have been fabricated on indium-doped tin oxide (ITO) electrodes using the pattern replication in nonwetting templates (PRINT) process. CdSe quantum dots (QDs) with an average diameter of 2.7 nm and a pyridine surface ligand were used for patterning. The PRINT technique utilizes a perfluoropolyether (PFPE) elastomeric mold that is tolerant of most organic solvents, thus allowing solutions of CdSe QDs in 4-picoline to be used for patterning without significant deformation of the mold. Nanometer-scale diffraction gratings have been successfully replicated with CdSe QDs.
[Show abstract][Hide abstract] ABSTRACT: Light-selective polymer films based on poly(ethylene-vinyl acetate) (PEVA) are of significant interest in emerging solar materials, including PV encapsulants and greenhouse plastic films. Quantum dots (QDs) have been shown to absorb UV light while transmitting light of higher wavelengths which potentially can be advantageous for enhancing PV efficiencies or in the case of greenhouse films, controlling plant growth. However, a simple procedure for integration of the QD nanocrystals into PEVA films with retention of the light selective properties has been elusive. In this work we report a simple procedure for loading QD nanocrystals into PEVA using a novel silane functionalized QD approach by simple melt-mixing in a twin-screw extruder. Both bare CdS and core-shell CdS-ZnS QDs were synthesized by colloidal chemistry using a facile single-molecular precursor method, and then functionalized with (3-mercaptopropyl)trimethoxysilane to improve their compatibility with PEVA. These nanocrystals were then melt-mixed into PEVA in a mini-compounder, with the resulting blends extruded and pressed into thin films using a Universal Film Maker and a Carver hydraulic press. Both experimental and commercial greenhouse films were analyzed by electron, confocal and atomic force microscopy, showing that the silane ligand enhanced dispersibility of QDs throughout the PEVA. The bare and core-shell QDs were studied at various loading levels from 0.1% to 0.5%, showing high light transmissions (90%) and decreased UV transmission with increased QD loading.
Solar Energy Materials and Solar Cells 04/2014; 123:30. DOI:10.1016/j.solmat.2013.12.007 · 5.34 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Microarray technology has been proved to be greatly helpful for biomedical and biological diagnosis. And the evaluation of its biological applications lies in the detection sensitivity, which requires high intensity and stability of the signal. Recently, several nanomaterials, especially semiconductor nanomaterials, due to their excellent fluorescence properties, have been widely used to construct microarrays for biosensors. Here, we presented an approach for constructing CdSe/ZnS quantum dot (QD) microarray in microfluidic channels on a glass slide by photolithography. The conditions for immobilizing stable and uniform QD microarray on the glass slide were optimized. Several types of QD microarrays with different emission wavelengths and modified groups were constructed using silanization and lithography technology. Based on the fluorescence quenching effect of Cu2+ on QDs, the microfluidic chip with QD microarray was applied for the determination of Cu2+. 1 nmol/L Cu2+ could be detected by this method.
[Show abstract][Hide abstract] ABSTRACT: Discrimination of stance and swing phases of the gait is required
for control of functional electrical stimulation (FES) used to assist
with ankle dorsiflexion in foot-drop problem. Simple thresholds applied
to a human whole nerve signal processed using a sophisticated digital
signal processing technique did not result in a safe and reliable
control method. In this preliminary study, the authors use the same
sensory signals to evaluate a gait event discriminator (GED), based on
Adaptive Logic Networks (ALNs). The evaluation was performed off-line
using neural signals for sensory feedback and a signal from a heel
switch as the output to the stimulator. The neural signal was recorded
using a cuff electrode implanted around the calcaneal nerve in the left
leg of a male subject and the heel switch was installed inside the shoe
of the same leg. Preliminary results suggest that ALNs can discriminate
precise timing of heel contact and heel lift during FES-assisted
walking. Restriction rules based on a priori knowledge were used to
verify decisions made by ALNs and to eliminate infrequent functional
errors providing maximum safety for the subject
Engineering in Medicine and Biology Society, 1996. Bridging Disciplines for Biomedicine. Proceedings of the 18th Annual International Conference of the IEEE; 12/1996
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