13196701
A biomimetic mass-flow transducer utilizing all-optofluidic generation of self-digitized, pulse code-modulated optical pulse trains.
We present a new mass-flow transducer producing responses in the form of optical pulse trains that are encoded with information on the strength and position of the stimulus. We implemented the self-digitization and encoding capabilities all-optofluidically, without involving external electronics, by integrating one optical fiber cantilever with multiple polymer optical waveguides on a microfluidic platform. The transducer can also be configured to respond only to transitional stimuli. These features closely mimic the rate-coding, action potential labeling, and rapid adaptation processes observed in biological mechanoreceptors and allow multiple transducers to transmit signals over a single, shared channel. We fabricated the transducer using polymer-based soft-lithography techniques. Its characterization confirmed the stimulus strength-dependent generation of optical pulses and the feasibility of multiplexing 2(n-1) to 2(n) transducers using n waveguides.
44805350
Numerical investigation of quasi-coplanar plasmonic waveguide-based photonic components.
Using 3-dimensional numerical simulations, we investigated the characteristics and performance of essential photonic components based on the recently proposed quasi-coplanar waveguide (QCPW) including bends, couplers, and splitters. The results confirmed the QCPW's potential in high density photonic integration. We also explored the application of various RF-originated concepts and techniques to QCPW-based photonic components to enhance and enrich their functionalities.
35716654
Elastomeric microwire-based optical gas flowmeter with stretching-enabled tunability in measurement range.
We report the utilization of transparent poly(dimethylsiloxane) (PDMS) microwires as the transducer for optical gas flowmetry. The elasticity of the PDMS microwire was exploited not only to miniaturize and simplify the flowmeter but also to widen and tune the measurement range through mechanical stretching. Using a 9 mm long microwire, we achieved 2.8~9.8 dB/SLM sensitivity. A 500 μm stretching of the microwire also shifted the measurement range from 1 to 4 SLM. The experimental results agreed well with predictions based on the fluid dynamic/optical model.
37028101
Sucrose-based fabrication of 3D-networked, cylindrical microfluidic channels for rapid prototyping of lab-on-a-chip and vaso-mimetic devices.
We present a new fabrication scheme for 3D-networked, cylindrical microfluidic (MF) channels based on shaping, bonding, and assembly of sucrose fibers. It is a simple, cleanroom-free, and environment-friendly method, ideal for rapid prototyping of lab-on-a-chip devices. Despite its simplicity, it can realize complex 3D MF channel architectures such as cylindrical tapers, internal loops, end-to-side junctions, tapered junctions, and stenosis. The last two will be of special use for realizing vaso-mimetic MF structures. It also enables molding with polymers incompatible with high-temperature processing.
32196097
Exciton-plasmon interactions in molecular spring assemblies of nanowires and wavelength-based protein detection.
Electronic interactions at the nanoscale represent one of the fundamental problems of nanotechnology. Excitons and plasmons are the two most typical excited states of nanostructures, which have been shown to produce coupled electronic systems. Here, we explore these interactions for the case of nanowires with mobile excitons and nanoparticles with localized plasmons and describe the theoretical formalism, its experimental validation and the potential practical applications of such nanoscale systems. Theory predicts that emission of coupled excitations in nanowires with variable electronic confinement is stronger, shorter and blue-shifted. These predictions were confirmed with a high degree of accuracy in molecular spring assemblies of CdTe nanowires and Au nanoparticles, where we can reversibly change the distance between the exciton and the plasmon. The prepared systems were made protein-sensitive by incorporating antibodies in the molecular springs. Modulation of exciton-plasmon interactions can serve as a wavelength-based biodetection tool, which can resolve difficulties in the quantification of luminescence intensity for complex media and optical pathways.
9605549
Spectrum measurement of fast optical signal of neural activity in brain tissue and its theoretical origin
Functional brain imaging technologies have enabled recent advances in understanding human brain function. In particular, a noninvasive and fast optical technique will become one of the most promising tools for future studies. As a fundamental ex vivo study for the development of such a technique, this paper demonstrates the spectral measurement of fast optical changes associated with neural activity in bulk brain tissue. For this purpose, a high-speed confocal near-infrared spectrometer was built and used. The results verified that observed transient optical responses (tORs) are associated with neural activity by showing that the following: tORs were concurrent and correlated with local field potentials (LFPs); tORs disappeared following tetrodotoxin application; and tORs were reproducibly observed across preparations. In addition, the amplitude of tORs was statistically significantly larger in longer wavelengths (approximately 1200 nm). The time course of tORs, however, is quite different from that of LFPs. Since this difference implies that tORs may originate not directly from the electric potential variation but from other neurophysiological events accompanying excitation, this paper tested the hypothesis that tORs are attributed to transient cellular volume changes (tCVCs). With no previous dynamic equation to elucidate such different temporal dynamics of the optical responses, a novel mathematical neuron model to describe tCVCs was developed. This neuron model, along with finite-difference time-domain simulations, showed that tCVCs and tORs were similar in the temporal dynamics, order of magnitude, response direction, and detectability in the bulk tissue; thus supporting the hypothesis.
1652703
Ankylosing spondylitis in a patient with myelodysplastic syndrome: an association with HLA-B27 or coincidence?
The authors report an unusual case of myelodysplastic syndrome (MDS) associated with ankylosing spondylitis (AS). A 40-year-old-man with MDS presented with chronic low back pain for 6 years. Four years ago, MDS was diagnosed during routine blood analysis for the work-up of his articular complaints. His initial articular complaints were attributed to extramedullary manifestations of MDS. Persistent low back pain with increasing intensity finally led the patient to seek medical attention. Radiograph of the pelvis showed bilateral asymmetric sacroiliitis. A diagnosis of AS was established on the basis of modified New York criteria. Although various autoimmune phenomena associated with MDS have been described, this is the first report of AS in the setting of MDS. Causal relationship between these two disorders is currently unknown. Increased risk of hematological diseases as well as AS in individuals with a positive HLA-B27 provides a feasible explanation for this rare observation.
26221478
Unbiased global optimization of Lennard-Jones clusters for N < or =201 using the conformational space annealing method.
We apply the conformational space annealing method to the Lennard-Jones clusters and find all known lowest energy configurations up to 201 atoms, without using extra information of the problem such as the structures of the known global energy minima. In addition, the robustness of the algorithm with respect to the randomness of initial conditions of the problem is demonstrated by ten successful independent runs up to 183 atoms. Our results indicate that this method is a general and yet efficient global optimization algorithm applicable to many systems.
7778854
Target deconvolution techniques in modern phenotypic profiling.
The past decade has seen rapid growth in the use of diverse compound libraries in classical phenotypic screens to identify modulators of a given process. The subsequent process of identifying the molecular targets of active hits, also called 'target deconvolution', is an essential step for understanding compound mechanism of action and for using the identified hits as tools for further dissection of a given biological process. Recent advances in 'omics' technologies, coupled with in silico approaches and the reduced cost of whole genome sequencing, have greatly improved the workflow of target deconvolution and have contributed to a renaissance of 'modern' phenotypic profiling. In this review, we will outline how both new and old techniques are being used in the difficult process of target identification and validation as well as discuss some of the ongoing challenges remaining for phenotypic screening.