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Ruthenium(II) polypyridyl complex [Ru(phen)2dppz-idzo]2+ as a colorimetric molecular “light switch” and powerful stabilizer for the RNA triplex poly(U)·poly(A)*poly(U)
摘要： The interaction of [Ru(phen)2dppz-idzo]2+ (phen = 1,10-phenanthroline, dppz-idzo = dppz-imidazolone) with triplex RNA poly(U)?poly(A)*poly(U) was carried out by using spectroscopic and viscometric techniques in this work. Luminescent titrations suggest that [Ru(phen)2dppz-idzo]2+ shows better selectivity for poly(U)?poly(A)*poly(U) compared with poly(U)?poly(A) and poly(U), this complex exhibits a “light switch” effect with an emission enhancement factor of about 123 in the presence of poly(U)?poly(A)*poly(U). Significantly, this “light switch” behavior could even be observed by the naked eye under irradiation with UV light. To our knowledge, [Ru(bpy)2dppz-idzo]2+ is the first small molecule able to serve as a colorimetric molecular “light switch” for the triplex poly(U)?poly(A)*poly(U). Combined with the spectral and viscometric results as well as [Ru(phen)2dppz-idzo]2+ stabilizing the template duplex poly(U)?poly(A), we speculate that [Ru(phen)2dppz-idzo]2+ prefers to bind with the Hoogsteen base-paired strand (the third strand) of the triplex, thus the intercalating [Ru(phen)2dppz-idzo]2+ stabilizing the third strand is more marked in comparison with the Watson-Crick base-paired duplex of the triplex. The results obtained here may be useful for understanding the interaction of triplex RNA poly(U)?poly(A)*poly(U) with small molecule, particularly ruthenium(II) complexes.
关键词： Ru(II) complexes,Stabilization,Triplex RNA,Colorimetic molecular light switch
更新于2025-09-23 15:23:52
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[IEEE 2018 9th International Conference on Information Technology in Medicine and Education (ITME) - Hangzhou, China (2018.10.19-2018.10.21)] 2018 9th International Conference on Information Technology in Medicine and Education (ITME) - Extracting Photoplethysmographic Waveform from Bulbar Conjunctiva Video
摘要： Recently the conjunctival vascularity measurement based on image analysis has shown great potential in physiological monitoring and biometrics. However, the motion artifacts in the conjunctiva videos cause both large displacement and distinct illumination variety. In this paper, a novel approach is proposed to extract photoplethysmographic waveform from conjunctiva video. Which consists of video stabilization and dual-channel extraction to eliminate the two facets of the motion artifacts respectively. The heart rate measuring results have shown a good agreement between our method and the fingertip oximeter.
关键词： conjunctiva vessel,pulse wave,video stabilization,illumination compensation
更新于2025-09-23 15:23:52
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A Novel Tilt Correction Technique for Irradiance Sensors and Spectrometers On-Board Unmanned Aerial Vehicles
摘要： In unstable atmospheric conditions, using on-board irradiance sensors is one of the only robust methods to convert unmanned aerial vehicle (UAV)-based optical remote sensing data to reflectance factors. Normally, such sensors experience significant errors due to tilting of the UAV, if not installed on a stabilizing gimbal. Unfortunately, such gimbals of sufficient accuracy are heavy, cumbersome, and cannot be installed on all UAV platforms. In this paper, we present the FGI Aerial Image Reference System (FGI AIRS) developed at the Finnish Geospatial Research Institute (FGI) and a novel method for optical and mathematical tilt correction of the irradiance measurements. The FGI AIRS is a sensor unit for UAVs that provides the irradiance spectrum, Real Time Kinematic (RTK)/Post Processed Kinematic (PPK) GNSS position, and orientation for the attached cameras. The FGI AIRS processes the reference data in real time for each acquired image and can send it to an on-board or on-cloud processing unit. The novel correction method is based on three RGB photodiodes that are tilted 10° in opposite directions. These photodiodes sample the irradiance readings at different sensor tilts, from which reading of a virtual horizontal irradiance sensor is calculated. The FGI AIRS was tested, and the method was shown to allow on-board measurement of irradiance at an accuracy better than ±0.8% at UAV tilts up to 10° and ±1.2% at tilts up to 15°. In addition, the accuracy of FGI AIRS to produce reflectance-factor-calibrated aerial images was compared against the traditional methods. In the unstable weather conditions of the experiment, both the FGI AIRS and the on-ground spectrometer were able to produce radiometrically accurate and visually pleasing orthomosaics, while the reflectance reference panels and the on-board irradiance sensor without stabilization or tilt correction both failed to do so. The authors recommend the implementation of the proposed tilt correction method in all future UAV irradiance sensors if they are not to be installed on a gimbal.
关键词： unmanned aerial vehicle,UAV,irradiance,reflectance factor,tilt stabilization,drone
更新于2025-09-23 15:23:52
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Assessing Physical Stability of Colloidal Dispersions Using Turbiscan Optical Analyzer
摘要： The physical stability of aqueous colloidal dispersions containing highly concentrated droplets of poorly water-soluble drugs has recently been identified as one of the main considerations in developing amorphous solid dispersions (ASDs). Turbiscan, an instrument based on multiple light scattering technology, was employed for the first time to assess colloidal dispersions with ritonavir as the model compound. The physical instability of ritonavir-rich droplets was monitored directly with and without the presence of candidate polymer additives at different drug concentrations and temperatures. The mechanism of the observed instability was confirmed to be coalescence of liquid droplets, based on the low glass transition temperature of water-saturated amorphous ritonavir determined using a newly developed experimental procedure. Temperature and solvent composition, within the range studied, have little influence on the kinetics of ritonavir coalescence. On the contrary, higher concentration of drug, i.e., more droplets per unit volume, greatly accelerates the coalescence process. In addition, polymers with varying degrees of hydrophobicity resulted in different levels of effectiveness in stabilization which is likely related to the strength of drug-polymer interactions and the corresponding differences in surface adsorption. This work demonstrates that the Turbiscan optical analyzer can be used as a rapid screening tool that provides a first-pass, high-throughput feasibility ranking of different excipients and additives to support the development of ASD formulations.
关键词： nanodroplets,coalescence,glass transition temperature,physical stability,stabilization,amorphous,ritonavir,colloidal dispersions,Turbiscan
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE International Conference on Consumer Electronics - Asia (ICCE-Asia) - Jeju (2018.6.24-2018.6.26)] 2018 IEEE International Conference on Consumer Electronics - Asia (ICCE-Asia) - Video Stabilization Using Feature-Based Classification
摘要： This paper proposed a video stabilization algorithm to cluster features before smoothing. Our method calculates the direction of movement from the features then estimate by directional statistics and K-mean to find out the global motion and motion of moving object. The motion will be smoothed by low pass Alpha-trimmed filter. The experimental show the effectiveness of our proposed method.
关键词： motion estimation,Video stabilization,clustering
更新于2025-09-23 15:22:29
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Invited Article: Tuning and stabilization of optomechanical crystal cavities through NEMS integration
摘要： Nanobeam optomechanical crystals, in which localized GHz frequency mechanical modes are coupled to wavelength-scale optical modes, are being employed in a variety of experiments across different material platforms. Here, we demonstrate the electrostatic tuning and stabilization of such devices, by integrating a Si3N4 slot-mode optomechanical crystal cavity with a nanoelectromechanical systems element, which controls the displacement of an additional 'tuning' beam within the optical near-field of the optomechanical cavity. Under DC operation, tuning of the optical cavity wavelength across several optical linewidths with little degradation of the optical quality factor (Q ≈ 105) is observed. The AC response of the tuning mechanism is measured, revealing actuator resonance frequencies in the 10 MHz–20 MHz range, consistent with the predictions from simulations. Feedback control of the optical mode resonance frequency is demonstrated, and alternative actuator geometries are presented.
关键词： optomechanics,tuning,NEMS,cavity optomechanics,stabilization
更新于2025-09-23 15:22:29
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The Growth Window of Ferroelectric Epitaxial Hf <sub/>0.5</sub> Zr <sub/>0.5</sub> O <sub/>2</sub> Thin Films
摘要： The metastable orthorhombic phase of hafnia is generally obtained in polycrystalline films, whereas in epitaxial films its formation has been much less investigated. We have grown Hf0.5Zr0.5O2 films by pulsed laser deposition and the growth window (temperature and oxygen pressure during deposition, and film thickness) for epitaxial stabilization of the ferroelectric phase is mapped. The remnant ferroelectric polarization, up to around 24 μC/cm2, depends on the amount of orthorhombic phase and strain, and increases with temperature and pressure for fixed film thickness. Leakage current decreases by increasing thickness and temperature, and particularly by reducing oxygen pressure. The coercive electric field (EC) depends on thickness (t) according the EC - t-2/3 scaling, which is observed by the first time in ferroelectric hafnia, and the scaling extends to thickness below 5 nm. The proven ability to tailor functional properties of high quality epitaxial ferroelectric Hf0.5Zr0.5O2 films paves the way towards progress in understanding their ferroelectric properties and prototyping devices.
关键词： Growth parameters,Pulsed laser deposition,Ferroelectric HfO2,Ferroelectric oxides,Epitaxial stabilization,Oxide thin films
更新于2025-09-23 15:22:29
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Generalized Content-Preserving Warp: Direct Photometric Alignment beyond Color Consistency
摘要： Motion estimation is vital in many computer vision applications. Most existing methods require high quality and large quantity of feature correspondence, and may fail for images with few textures. In this paper, a photometric alignment method is proposed to obtain better motion estimation result. Since the adopted photometric constraints are usually limited to required illumination or color consistency assumption, a new Generalized Content-Preserving Warp (GCPW) framework therefore is designed to perform photometric alignment beyond color consistency. Similar to conventional Content-Preserving Warp (CPW), GCPW is also a mesh-based framework, but it extends CPW by appending a local color transformation model for every mesh quad, which expresses the color transformation from a source image to a target image within the quad. Motion-related mesh vertexes and color-related mapping parameters are optimized jointly in GCPW to get more robust motion estimation result. Evaluation of tens of videos reveals that the proposed method achieves more accurate motion estimation results. More importantly, it is robust to significant color variation. Besides, this paper explores the performance of GCPW in two popular computer vision applications: image stitching and video stabilization. Experimental results demonstrate GCPW's effectiveness in dealing with typical challenging scenes for these two applications.
关键词： Color Difference,Video Stabilization,Photometric Constraint,Image Stitching,Motion Estimation
更新于2025-09-23 15:21:21
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Minimizing Defect States in Lead Halide Perovskite Solar Cell Materials
摘要： In order to reach the theoretical e?ciency limits of lead-based metal halide perovskite solar cells, the voltage should be enhanced because it su?ers from non-radiative recombination. Perovskite materials contain intrinsic defects that can act as Shockley–Read–Hall recombination centers. Several experimental and computational studies have characterized such defect states within the band gap. We give a systematic overview of compositional engineering by distinguishing the di?erent defect-reducing mechanisms. Doping e?ects are divided into in?uences on: (1) crystallization; (2) lattice properties. Incorporation of dopant in?uences the lattice properties by: (a) lattice strain relaxation; (b) chemical bonding enhancement; (c) band gap tuning. The intrinsic lattice strain in undoped perovskite was shown to induce vacancy formation. The incorporation of smaller ions, such as Cl, F and Cd, increases the energy for vacancy formation. Zn doping is reported to induce strain relaxation but also to enhance the chemical bonding. The combination of computational studies using (DFT) calculations quantifying and qualifying the defect-reducing propensities of di?erent dopants with experimental studies is essential for a deeper understanding and unraveling insights, such as the dynamics of iodine vacancies and the photochemistry of the iodine interstitials, and can eventually lead to a more rational approach in the search for optimal photovoltaic materials.
关键词： semiconductor,solar energy,photovoltaics,doping,thin ?lm materials,voltage loss,stabilization,optimization,charge generation,light harvesting
更新于2025-09-23 15:21:01
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A direct diode pumped Ti:sapphire laser with single-frequency operation for high resolution spectroscopy
摘要： A direct diode pumped continuous-wave Ti:sapphire laser (DDPTS) is presented. A bow-tie geometry with optical diode is chosen for unidirectional single-mode operation. Frequency selection is performed with a standard combination of birefringent filter and etalon. To accomplish mode-hop free frequency tuning the piezo-driven etalon is stabilized to one of the cavity modes via dither-locking method. To suppress environmental fluctuations the cavity-mode is additionally locked to an external optical cavity with low frequency drift. Feasibility of the setup for high-resolution spectroscopy is demonstrated by saturated absorption spectroscopy of the D2 line of Rubidium.
关键词： Rubidium,Stabilization,Hyperfine structure,Laser,Titanium:sapphire,Optical cavity,Beatnote
更新于2025-09-23 15:21:01