Design and kinematic optimization of a novel underactuated robotic hand exoskeleton

This study presents the design and the kinematic optimization of a novel, underactuated, linkage-based robotic hand exoskeleton to assist users performing grasping tasks. The device has been designed to apply only normal forces to the finger phalanges during flexion/extension of the fingers, while providing automatic adaptability for different finger sizes. Thus, the easiness of the attachment to the user’s fingers and better comfort have been ensured. The analyses of the device kinematic pose, statics and stability of grasp have been performed. These analyses have been used to optimize the link lengths of the mechanism, ensuring that a reasonable range of motion is satisfied while maximizing the force transmission on the finger joints. Finally, the usability of a prototype with multiple fingers has been tested during grasping tasks with different objects.     

Enhanced molecular fluorescence near thick Ag island film of large pseudotabular nanoparticles

A highly reflective thick Ag island film (TAIF) sputter-grown on mica, consisting of unique large pseudotabular nanoislands, 60-200 nm across and 30-60 nm thick, produced an unusually strong surface enhanced fluorescence (SEF) for rhodamine dyes situated very close to (only approximately 10 A away from) the metal surface. A significantly greater part of the enhanced fluorescence was emitted into the back half space through TAIF and the mica substrate. The detailed fluorescence angular distribution was very similar to that of the light scattering by TAIF, suggesting that the enhanced emission originated from some large induced dipoles in TAIF. For reference, we also present a quantitative analysis of the fluorescent behavior of the same dye but directly coated on a reference glass surface. TAIF showed no distinct dipolar surface plasmon-like bands for excitation at normal incidence, and the light absorption by dye-coated TAIF could be described by simple superposition of the contribution of TAIF and that of the surface-bound dyes. However, the net dye absorptance was increased by 4-5 times due to the strong interactions of the dye transition dipoles with the TAIF-scattered fields. The estimated SEF quantum yield in the low dye coverage limit suggests a markedly high radiative yield of the induced dipole in TAIF around approximately 0.5.     

Adsorption properties of CO on low-index Pt3Sn surfaces

The adsorption properties of CO on Pt₃Sn were investigated by utilizing quantum mechanical calculations. The (1 1 1), (1 1 0) and (0 0 1) surfaces of Pt₃Sn were generated with all possible bulk terminations, and on these terminations all types of active sites were determined. The adsorption energies and the geometries of the CO molecule at those sites were found. Those results were compared with the results obtained from the adsorption of CO on similar sites of Pt(1 1 1), Pt(1 1 0) and Pt(0 0 1) surfaces. The comparison reveals that adsorption of CO is stronger on Pt surfaces; this may be the reason why catalysts with Pt₃Sn phase do not suffer from CO posioning in experimental works. Aiming to understand the interactions between CO and the metal adsorption sites in detail, the local density of states (LDOS) profiles were produced for atop-Pt adsorption, both for the carbon end of CO for its adsorbed and free states, and for the Pt atom of the binding site. LDOS profiles of C of free and adsorbed CO and Pt for corresponding pure Pt surfaces, Pt(1 1 1), Pt(1 1 0) and Pt(0 0 1) were also obtained. The comparison of the LDOS profiles of Pt atoms of atop adsorption sites on the same faces of bare Pt₃Sn and Pt surfaces showed the effect of alloying with Sn on the electronic properties of Pt atoms. Comparison of LDOS profiles of the C end of CO in its free and atop adsorbed states on Pt₃Sn and LDOS of Pt on bare and CO adsorbed Pt₃Sn surface were used to clear out the electronic changes occurred on CO and Pt upon adsorption. The study showed that (i) inclusion of a Sn atom at the adsorption site structure causes dramatic decrease in stability which limits the number of possible CO adsorption sites on Pt₃Sn surface, (ii) the presence of Sn causes angles different from 180° for M-C-O orientation, (iii) the presence of Sn in the neighborhood of Pt on which CO is adsorbed causes superposition of the 5σ/1π derived-state peaks at the carbon end of CO and changes in adsorption energy of CO, (iv) Sn present beneath the adsorption site strengthens the CO adsorption, whereas neighboring Sn on the surface weakens it for all Pt₃Sn surfaces tested and (v) the most stable site for CO adsorption is the atop-Pt site of the mixed atom termination of Pt₃Sn(1 1 0).     

Use of Magnetic Nanoparticles and a Microplate Reader with Fluorescence Detection to Detect C‐reactive Protein

Two approaches based on magnetic nanoparticles (MNPs) have been compared to analyze C‐reactive protein (CRP). Both the non‐eluted and eluted MNP‐1°Ab‐CRP‐2°Ab/FITC bioconjugates were measured by a microplate reader with fluorescence detection. The linear ranges for the non‐elution and elution methods were 10‐200 and 0.1‐2.0 μg/mL, respectively. The concentration limits of detection for the nonelution and elution methods were 2.91 and 0.04 μg/mL, respectively. The non‐ elution method gave better precision and recovery than the elution method, and also showed comparable results to that of ELISA assay. The non‐elution method is simple and only needs minute volumes of sample and buffer. There is no need to dissociate the fluorescence probes from the bioconjugates, and the fluorescence signals can be directly measured on the MNP‐1°Ab‐CRP‐2°Ab/FITC bioconjugates. Meanwhile, samples with high CRP concentrations are not necessarily to be diluted before analysis.     

Convergent synthesis of near-infrared absorbing, "push-pull", bisthiophene-substituted, zinc(II) phthalocyanines and their application in dye-sensitized solar cells

Zinc(II) phthalocyanine dyes that contain triarylamine-terminated bisthiophene and hexylbisthiophene groups have been synthesized by a convergent approach by using carboxytriiodo-ZnPc as a precursor. Further transformation of the iodo groups by a Pd-catalyzed reaction allowed easy preparation of further extended π-conjugated carboxy-ZnPcs. These dyes have been used as sensitizers in dye-sensitized solar cells, which exhibit a panchromatic response and moderate overall efficiencies.     

Novel lasing action in dye-doped polymer films coated on large pseudotabular Ag islands

An approximately 15 microm thick polymer film doped (approximately 5 mM) with a laser dye, when coated on large pseudotabular Ag islands and pumped by a nanosecond laser, generated a single sharp stimulated emission with a bandwidth down to 2.5 nm. We attribute this novel, low-threshold (approximately 1 mJ/cm(2)) lasing action to the surface-enhanced fluorescence of the dyes very near the Ag islands. This highly surface-sensitive lasing concept was supported by the fact that the lasing action was almost completely eliminated by separating the Ag islands and the dye-doped polymer film with a molecularly thin (approximately 14 A) spacer.     

Carbon nanotubes/alizarin red S–poly(vinylferrocene) modified glassy carbon electrode for selective determination of dopamine in the presence of ascorbic acid

A modified electrode was fabricated by electrochemical formation of poly(vinylferrocene) on the multi-wall carbon nanotube-alizarin red S matrix covered glassy carbon electrode. A higher electrochemical activity was obtained to the electrocatalytic oxidation of dopamine. The electrode surface was characterized electrochemically and spectroscopically. Poly(vinylferrocene) (PVF) in electrode was used as an electron transfer mediator in the electrochemical oxidation of compounds due to its perfect reversible redox properties. Multi-wall carbon nanotubes (MWCNTs) / alizarin red S (ARS)–PVF electrode was used to the determination of dopamine in the presence of ascorbic acid in 0.1 M sulphate buffer solution at pH 7. The performance of the MWCNTs/ARS–PVF electrode was evaluated by DPV and amperometry.     

Detection of formaldehyde using mid-infrared difference-frequency generation

3 (PPLN) is reported. Minimum detectable concentration of 30 ppb was achieved with a compact, portable room-temperature gas sensor configured for formaldehyde (H₂CO) detection. This sensitivity, coupled with high selectivity and long term stability, is sufficient for various environmental applications. Received: 29 September 1997     

Dispersion of mass by two-dimensional homogeneous and incompressible Çinlar flows

We consider the dispersion of passive tracers in stationary, homogeneous and incompressible Çinlar flows on the plane. The associated velocity field is generated by the superposition of eddies of various size, arrival time and location which form a Poisson point process. Our focus is on the dispersion of a tracer cloud, which is measured through the variance of its centroid and the mean of the dispersion tensor. We also study single particle dispersion and particle pair separations in conjunction with dispersion. Monte Carlo simulations of all these measures first establish the relation of the dispersion to the parameters of the flow model. Second, the physical predictions on the behavior of these measures with respect to time as well as their relationship to each other are confirmed.