A novel one-dimensional photonic crystal fishbone (FB) with surface wave is proposed. Via designing high quality FB nanocavity, high sensitivity for optical sensing and strong optical force for ...optical trapping in fluidics can be obtained.
In this report, we propose a square lattice photonic crystal hetero-slab-edge microcavity design. In numerical simulations, three surface modes in this microcavity are investigated and optimized by ...tuning the slab-edge termination τ and gradual mirror layer. High simulated quality (Q) factor of 2.3 × 10(5) and small mode volume of 0.105 μm(3) are obtained from microcavity with τ = 0.80. In experiments, we obtain and identify different surface modes lasing. The surface mode in the second photonic band gap shows a very-low threshold of 140 μW and high Q factor of 5,500, which could be an avenue to low-threshold optical lasers and highly sensitive sensor applications with efficient light-matter interactions.
We propose a point-shifted nanocavity based on square lattice photonic crystal, which sustains a lowest-order whispering-gallery (WG) mode. In simulation, the optimized WG mode (quality (Q) factor ...approximately 14,000) in point-shifted nanocavity can be with smaller mode volume (approximately 5.5(lambda/2n)(3)) but larger nano-post tolerance than those in single-defect cavity design. From well-fabricated device, single WG mode lasing with measured Q factor of 4,100 and low threshold of 160 microW is obtained. Besides, we also observe the changed polarization of WG mode due to modal symmetry breaking caused by the presence of a nearby dielectric nano-particle, which would be useful in sensing molecule binding or attaching for bio-chemical applications.
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Parkinson’s Disease (PD), a major neurodegenerative disorder, is characterized by chronic and progressive loss of dopaminergic neurons ultimately leading to death. Leucine‐rich repeat ...kinase 2 (LRRK2) is one of the greatest known genetic contributors to PD. LRRK2 is a large multi‐domain protein that contains a kinase domain as well as a Ras/GTPase (ROC) domain, followed by a COR domain. LRRK2 also acts as scaffold for the assembly of signaling complexes with its armadillo, ankyrin, leucine‐rich and WD40 domains at the N‐ and C‐termini. Studies have shown that most of the common familial mutations resulted in the formation of fibrous structures docked on microtubules in cells. However, how the fibrous structure is associated with LRRK2 activation is still unclear. Little is known about how LRRK2 activity is regulated, as well as the pathogenic mechanisms that drive PD. In this study, we use hydrogen‐deuterium exchange mass spectrometry (HDX‐MS) to measure the solvent exposed regions of LRRK2. Purified truncated LRRK2 (RCKW), which includes ROC, COR, kinase and WD40 domain, was used to map conformational changes associated with ATP, GTP and kinase inhibitor binding. Mutations in the kinase domain, including two familial mutations (G2019S and I2020T), are characterized as well. This information will help us to understand the protein interfaces within and between LRRK2 oligomers involved in LRRK2 activity. Also, it will help to understand the conformation that drives the activation of LRRK2 and pathological docking onto microtubules.
Tunable nanolasers via 1D nanoblocks embedded within polydimethylsiloxane are demonstrated, which show large wavelength tunability of 7.65nm per 1% stretching and high reliability under repeating ...stretching/relaxing tests. Wide tuning range over 80nm is achieved. As a stretching sensor, minimum detectable stretching of 0.072% is obtained.
We propose and demonstrate an improved method for transfer printing that allows for the accurate docking of a photonic crystal nanobeam (NB) laser onto a SiN x waveguide. Our proposed method enables ...achieving much smaller transfer printing misalignments compared to the conventional approach based on visual alignment in experiments. We tested our method by docking a modified NB laser design with a theoretical unidirectional coupling efficiency of 64% to the SiN x waveguide. The results show a mean rotational misalignment of only 0.08° and a mean displacement misalignment of 26 nm for 48 NB lasers docked at the SiN x waveguides, demonstrating the high accuracy and excellent transfer printing reproducibility of our proposed method. Additionally, measurements indicated that over 97% of these highly accurate docked NB lasers exhibited uniform unidirectional coupling to specific waveguide output facets. We believe that the improved transfer printing steps presented in this study, along with the corresponding hybrid integration of docking NB lasers at the SiN x waveguide, provide a highly promising method for accurately integrating nanowire-based light sources into silicon-based photonic integrated circuits.
Small interfering RNAs (siRNAs) have become the most powerful and widely used gene silencing reagents for reverse functional genomics and molecular therapeutics. The key challenge for achieving ...effective gene silencing in particular for the purpose of the therapeutics is primarily dependent on the effectiveness and specificity of the RNAi targeting sequence. However, only a limited number of siRNAs is capable of inducing highly effective and sequence-specific gene silencing by RNA interference (RNAi) mechanism. In addition, the efficacy of siRNA-induced gene silencing can only be experimentally measured based on inhibition of the target gene expression. Therefore, it is important to establish a fully robust and comparative validating system for determining the efficacy of designed siRNAs. In this study, we have developed a reliable and quantitative reporter-based siRNA validation system that consists of a short synthetic DNA fragment containing an RNAi targeting sequence of interest and two expression vectors for targeting reporter and triggering siRNA expression. The efficacy of the siRNAs is measured by their abilities to inhibit expression of the targeting reporter gene with easily quantified readouts including enhanced green fluorescence protein (EGFP) and firefly luciferase. Using fully analyzed siRNAs against human hepatitis B virus (HBV) surface antigen (HBsAg) and tumor suppressor protein p53, we have demonstrated that this system could effectively and faithfully report the efficacy of the corresponding siRNAs. In addition, we have further applied this system for screening and identification of the highly effective siRNAs that could specifically inhibit expression of mouse matrix metalloproteinase-7 (MMP-7), Epstein–Barr virus (EBV) latent membrane protein 1 (LMP1), and human serine/threonine kinase AKT1. Since only a readily available short synthetic DNA fragment is needed for constructing this novel reporter-based siRNA validation system, this system not only provides a powerful strategy for screening highly effective siRNAs but also implicates in the use of RNAi for studying novel gene function in mammals.
In this report, we investigate a photonic crystal circular-shaped microcavity (removing seven air holes) sustaining whispering-gallery mode (WGM) by shifting the 12 nearest air holes according to the ...concept of cavity-shaping in micro-disk and micro-gear lasers. The WGM modal characteristics are investigated by three-dimensional (3D) finite-difference time-domain (FDTD) simulations. From well-fabricated devices and simulated results, we obtain and identify WGM single-mode lasing with low threshold and high measured quality factor. By inserting additional waveguides, we also investigate its uniform coupling behaviors in different waveguide-cavity-waveguide geometries in both FDTD simulations and experiments.
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