Imaging through dynamic scattering media with stitched speckle patterns

Imaging through scattering media via speckle autocorrelation is a popular method based on the optical memory effect.However,it fails if the amount of valid information acquired is insufficient due to a limited sensor size.In this Letter,we reveal a relationship between the detector and object sizes for the minimum requirement to ensure image reconstruction by defining a sampling ratio R,and propose a method to enhance the image quality at a small R by capturing multiple frames of speckle patterns and piecing them together.This method will be helpful in expanding applications of speckle autocorrelation to remote sensing,underwater probing,and so on.

Seeing through dynamics scattering media:Suppressing diffused reflection based on decorrelation time difference

We observed a phenomenon that different scattering components have different decorrelation time.Based on decorrelation time difference,we proposed a method to image an object hidden behind a turbid medium in a reflection mode.In order to suppress the big disturbance calused by reflection and back scattering,two framnes of speckles are recorded in sequence,and their difference is used for image reconstruction.Our method is immune to both medium motions and object movements.

In situ nanobubble sizing by visualization particle tracking and image-based dynamic light scattering

A novel method combining visualization particle tracking with image-based dynamic light scattering was developed to achieve the in situ and real-time size measurement of nanobubbles(NBs).First,the in situ size distribution of NBs was visualized by dark-field microscopy.Then,real-time size during the preparation was measured using image-based dynamic light scattering,and the longitudinal size distribution of NBs in the sample cell was obtained in a steady state.Results show that this strategy can provide a detailed and accurate size of bubbles in the whole sample compared with the commercial ZetaSizer Nano equipment.Therefore,the developed method is a real-time and simple technology with excellent accuracy,providing new insights into the accurate measurement of the size distribution of NBs or nanoparticles in solution.

Thermal Transport in Methane Hydrate by Molecular Dynamics and Phonon Inelastic Scattering

The heat conduction and thermal conductivity for methane hydrate are simulated from equilibrium molecular dynamics. The thermal conductivity and temperature dependence trend agree well with the experimental results. The nonmonotonic temperature dependence is attributed to the phonon inelastic scattering at higher temperature and to the confinement of the optic phonon modes and low frequency phonons at low temperature. The thermal conductivity scales proportionally with the van der Waals interaction strength, The conversion of a crystal-like nature into an amorphous one oecurs at higher strength. Both the temperature dependence and interaction strength dependence are explained by phonon inelastic scattering.

Dynamic Behavior and Mass Transport in Polyacrylic Acid Gel by Dynamic Light Scattering

Dynamic behaviors on polyacrylic acid (PAA) gels and mass (small molecules) transports in the gels have been studied mainly by dynamic light scattering (DLS). The cross-linking degree (fc), monomer concentration (Cm) and temperature of the gels have significant influences on its dynamic behavior and mass transport in the gels. The increase of fc leads to decrease of the mesh sizes of the gels, thus the obstacle of the gels for mass transport is increased. As a result, small molecular diffusion Dk in the gels is decreased. So even if for small molecules, the Dk also is influenced.

DYNAMIC LIGHT SCATTERING STUDY ON TRANSLATION DIFFUSION OF 8-ARM STAR POLYSTYRENE IN GOOD AND THETA SOLVENTS

The technique of dynamic light scattering has been used to investigate the translation diffusion behavior of 8-arm star polystyrene (SPS)in a good solvent, tetrahydrofuran (THF) or benzene (BZ) and a theta solvent, cyclohexane (CH), by homodyne photon correlation spectroscopy .The intensityintensity autocorrelation function was analyzed by the method of cumulant. The translation diffusion coefficients have been obtained as a function of temperature and concentration. Under theta condition ,the non-concentration dependence of diffusion coefficient showed the unperturbed Gaussian state o the SPS molecular chain. The different hydrodynamic radii estimated from Stokes- Einstein equation reflected the stretch extent of the arm chain for regular star polymer. The data of diffusion activation energy of SPS in THF, BZ and CH were also obtained respectively.

EARLY CATARACT DETECTION BY DYNAMIC LIGHT SCATTERING WITH SPARSE BAYESIAN LEARNING

Dynamic light scattering(DLS)is a promising technique for early cataract detection and for studying cataractogenesis.A novel probabilistic analysis tool,the sparse Bayesian learning(SBL)algorithm,is described for reconstructing the most-probable size distribution ofα-crystallin and their aggregates in an ocular lens from the DLS data.The performance of the algorithm is evaluated by analyzing simulated correlation data from known distributions and DLS data from the ocular lenses of a fetal calf,a Rhesus monkey,and a man,so as to establish the required efficiency of the SBL algorithm for clinical studies.

Using Refined Theory to Studied Elastic Wave Scattering and Dynamic Stress Concentrations in Plates with Two Cutouts

In this paper, based on complex variables and conformal mapping methods, using the refined dynamic equation of plates, elastic wave scattering and dynamic stress concentrations in plates with two cutouts were studied. Applying the orthogonal function expansion method, the problem to be solved can be reduced into the solution of a set of infinite algebraic equations. According to free boundary conditions, numerical results of dynamic moment concentration factors in thick plates with two circular cutouts analyze that: there will be more complex interaction changes between two-cutout situation than single cutout situation. In the case of low frequency or high frequency and thin plate, the hole-spacing in the absence of coupling interactions was larger or smaller. The numerical results and method can be used to analyze the dynamics and strength of plate-like structures.

Dynamic stress concentrations in thick plates with two holes based on refined theory

Based on complex variables and conformal mapping, the elastic wave scat- tering and dynamic stress concentrations in the plates with two holes are studied by the refined dynamic equation of plate bending. The problem to be solved is changed to a set of infinite algebraic equations by an orthogonM function expansion method. As examples, under free boundary conditions, the numerical results of the dynamic moment concen- tration factors in the plates with two circular holes are computed. The results indicate that the parameters such as the incident wave number, the thickness of plates, and the spacing between holes have great effects on the dynamic stress distributions. The results are accurate because the refined equation is derived without any engineering hypothese.

Sparsity-based efficient simulation of cluster targets electromagnetic scattering

An efficient and real-time simulation method is proposed for the dynamic electromagnetic characteristics of cluster targets to meet the requirements of engineering practical applications.First,the coordinate transformation method is used to establish a geometric model of the observation scene,which is described by the azimuth angles and elevation angles of the radar in the target reference frame and the attitude angles of the target in the radar reference frame.Then,an approach for dynamic electromagnetic scattering simulation is proposed.Finally,a fast-computing method based on sparsity in the time domain,space domain,and frequency domain is proposed.The method analyzes the sparsity-based dynamic scattering characteristic of the typical cluster targets.The error between the sparsity-based method and the benchmark is small,proving the effectiveness of the proposed method.

Applying dynamic light scattering to investigate the self-assembly process of DNA nanostructures

Understanding the dynamic assembly process of DNA nanostructures is important for developing novel strategy to design and construct functional devices.In this work,temperature-controlled dynamic light scattering(DLS)strategy has been applied to study the global assembly process of DNA origami and DNA bricks.Through the temperature dependent size and intensity profiles,the self-assembly process of various DNA nanostructures with different morphologies have been well-studied and the temperature transition ranges could be observed.Taking advantage of the DLS information,rapid preparation of the DNA origami and the brick assembly has been realized through a constant temperature annealing.Our results demonstrate that the DLS-based strategy provides a convenient and robust tool to study the dynamic process of forming hieratical DNA structures,which will benefit understanding the mechanism of self-assembly of DNA nanostructures.

Polarized imaging dynamic light scattering for simultaneous measurement of nanoparticle size and morphology

The performance of nanoparticles is often affected by particle size and morphology.Currently,electron microscopy or atomic force microscopy is typically utilized to determine the size and morphology of nanoparticles.However,there are issues such as difficult sample preparation,long processing times,and challenges in quantitative characterization.Therefore,it is of great significance to develop a fast,accu-rate,and statistical method to measure the size and morphology of nanoparticles.In this study,a new method,called polarized imaging dynamic light scattering(PIDLS),is proposed.The nanoparticles are irradiated with a vertical linearly polarized laser beam,and a polarization camera collected the dynamic light scattering images of particles at four different polarization directions(0°,45°,90°,and 135°)at a scattering angle of 90°.The average particle size and distribution are obtained using the imaging dy-namic light scattering method at 0°polarization direction,and the morphology of the particles is ob-tained based on the depolarization patterns of the scattered light.The optical sphericityΦis defined based on the degree of linear polarization(DoLP).It is also implemented for the quantitative evaluation of the sphericity of the nanoparticles,including spherical,octahedral,nanoplate,nanorod,and linear ones.Together with the Poincarésphere parameterψ,the morphology of the nanoparticles can be roughly identified.In addition,PIDLS enables the measurement of particle size and morphology distributions simultaneously for evaluating the uniformity of particles.The effectiveness of PIDLS is verified by the measurement of five kinds of industrial titanium dioxide as well.

A regularization algorithm of dynamic light scattering for estimating the particle size distribution of dual-substance mixture in water

Dynamic light scattering(DLS)is a nondestructive,well-established technique for the size characterization of proteins,nanoparticles,polymers,and colloidal dispersions.However,current DLS techniques are only applied to particle groups of single composition due to the limitation of their inversion algorithm.In this study,we propose a particle size distribution inversion algorithm based on the Tikhnonov regularization method that can be applied to the dual-substance particle mixture.The algorithm retrieves the particle size distributions of two substances,respectively,by taking advantage of their refractive index differences.The simulation results reveal that the algorithm has excellent accuracy and stability when the scattering angle is 30°.Instead of the original identity matrix,the first-order difference matrix and second-order difference matrix are used as the regular matrix when utilizing the Tikhnonov algorithm,which obviously improves the anti-interference,accuracy,and stability of the algorithm.Furthermore,the inversion of particle size distribution is carried out at a 0.01%–1%noise level,which shows that the algorithm has an available antinoise ability.Finally,experimental particle size measurements for a mixture of polystyrene beads and toner particles demonstrate that the proposed algorithm is superior to the traditional Tikhnonov algorithm in applicability and accuracy.

Performance of branched-chain extended surfactant mixed with zwitterionic or cationic surfactant

2-Hexyl-1-decanol was used as the main material to prepare a block-polyether sulfonate extended surfactant(IC_(16)P_(6)E_(6)S).The solubility and surface active properties of IC_(16)P_(6)E_(6)S were evaluated,and then the IC_(16)P_(6)E_(6)S was mixed with a cationic surfactant hexadecyl trimethyl ammonium bromide(CTAB)and a zwitterionic betaine surfactant(HAB),respectively.The effects of mixing ratios of IC_(16)P_(6)E_(6)S∶HAB and IC_(16)P_(6)E_(6)S∶CTAB on the hydrodynamic diameter and interfacial properties were discussed.The emulsification,adsorption and laboratory core displacement experiments of the binary system were tested.The results showed that the critical micelle concentration(cmc)of IC_(16)P_(6)E_(6)S in distilled water was 0.1 mmol/L and the surface tension at cmc(γcmc)was 28.53 mN/m.IC_(16)P_(6)E_(6)S showed strong synergistic effects with HAB and CTAB,and the mixed systems could effectively reduce the interfacial tension compared with single surfactants.The mixed systems with n(IC_(16)P_(6)E_(6)S)∶n(HAB)of 1∶1 and n(IC_(16)P_(6)E_(6)S)∶n(CTAB)of 1∶3 could maintain ultra-low interfacial tension(in the order of magnitude of 10^(-3)mN/m)in the salinity range of 1%-7%NaCl and low interfacial tension(in the order of magnitude of 10^(-2)mN/m)in the salinity range of 3%-7%NaCl,respectively.With the increase of salinity,the emulsion formed by the mixed surfactant system underwent the phase transition process from WinsorⅠto WinsorⅢand then to WinsorⅡ.The emulsion of mixed IC_(16)P_(6)E_(6)S/HAB system had more middle-phase emulsion volume than that of the mixed IC_(16)P_(6)E_(6)S/CTAB system,and the former emulsion system was more stable.The mixed IC_(16)P_(6)E_(6)S/HAB system also had good solubilization effect,and the amount of oil solubilization was up to 43 mL/g.Meanwhile,it had good adsorption resistance.Compared with water flooding,the depressurization rate could reach 25.00%and the recovery could be enhanced by 11.75%,indicating that the IC_(16)P_(6)E_(6)S/HAB system was more conducive to the depressurization and injection enhancement for low-permeability reservoirs.

Study of asphaltene reaggregation in toluene/heptane mixture by dynamic and static light scattering

This paper presents the study of the effect of multiple ultrasonic impacts on submicron asphaltene aggregates in a toluene/heptane solution,conducted with dynamic light scattering technique.The objects of the study were four samples of asphaltenes obtained from four different oils.For all samples,the change in the average size of the asphaltene submicron aggregates with time was measured after the addition of a precipitant(heptane)to a solution of asphaltenes in toluene at an amount above the threshold concentration.Asphaltene aggregates formed in solution after the addition of the precipitant and were subjected to ultrasonic treatment,which led to the destruction of the asphaltene aggregates.Aggregation of destroyed asphaltenes was observed.The kinetics of this aggregation were similar to the kinetics of aggregation of asphaltenes after the addition of a precipitant.Multiple iterations of asphaltene aggregate destruction in the sample led to a significant change in the kinetics of aggregation:the growth of aggregates slowed and stabilized at a size of approximately 200 nm and 30 nm for the different studied samples.

Synthesis of Nanometer Cobalt Blue Pigment by Microemulsion Method and Control of Diameter of Particle

The nanometer cobalt blue pigments were prepared by microemulsion method. Using dynamic light scattering(DLS) test method, the influences of water content on the size of liquid drop of microemulsion and the liquid drop of microemulsion on the final diameter of nanometer particle were studied in the course of preparation. Accordingly, the method to control the diameter of nanometer particle by changing water content was established. The nanometer cobalt blue particles were confirmed by XRD and TEM. Color parameters of pigments were determined. The quantum size effect of the pigments was discussed.

Infrared Sensor with Liquid Crystal Chopper

An infrared sensor using the liquid crystal chopper is presented. The infrared sensor is designed to detect infrared rays with a pyroelectric element used as a liquid crystal chopper in such an infrared sensor or the like.

Synthesis of Silica Particles with Precisely Tailored Diameter

A modified seeded growth process of silica particles with a continuous addition of tetraethyl orthosilicate （TEOS） was presented to control the diameter of silica particles. The diameter of particles was monitored by dynamic light scattering to control the addition of TEOS. The increase in the diameter of the silica particles with time and the addition of TEOS was investigated. The diameter of silica seeds increased from 193 nm to 446 nm in 4 h. The final diameter of silica particles was tailored within the range of ±5 nm to the target diameter. Silica particles with diameter of 446 nm were synthesized and assembled into photonic crystals with a pseudo band gap centered at just 1000 nm. The feasibility and practicability of this modified seeded growth process was verified.

Electromagnetic scattering characteristics of coaxial helicopter based on dynamic transformation method

With the development of coaxial rotors and high-speed helicopters, the electromagnetic scattering characteristics of coaxial helicopters have gradually become a research hotspot. In order to deal with the Radar Cross-Section(RCS) of high-speed rotating rotors or coaxial main rotors, a Dynamic Scattering Method(DSM) based on dynamic process simulation and grid coordinate transformation is presented. Instantaneous electromagnetic scattering from rotors and helicopters is solved using Physical Optics(PO) and Physical Theory of Diffraction(PTD). Important factors are analyzed and discussed in detail, including individual rotor rotation, azimuth, elevation angle,fuselage, pitch angle, and roll angle. The results show that the electromagnetic scattering characteristics of rotor-type components are dynamic and periodic. The dynamic RCS period of a single rotor is related to the dynamic RCS period of the coaxial main rotor. Choosing different observation angles and attitude angles has a great impact on the static and dynamic RCS of the helicopter.The presented DSM is effective and efficient to analyze and determine the dynamic electromagnetic scattering characteristics of conventional helicopters or coaxial helicopters.

Spontaneous Vesicle Formation in Mixed Aqueous Solution of Poly-tailed Cationic and Anionic Surfactants

Spontaneous vesicles from the mixed aqueous solution of poly-tailed cationic surfactant PTA and anionic surfactant AOT are firstly obtained. Vesicle formation and characterizations are demonstrated by negative-staining TEM and dynamic light scattering. A monodisperse vesicle system is obtained with a polydispersity of 0.082. Ultrasonication can promote the vesicle formation. Mechanism of vesicle formation is discussed from the viewpoint of molecular interaction.