Side Scattering Research Articles

Numerical model for linear stimulated Raman scattering in inhomogeneous plasmas

Numerical model for calculating convective gains and absolute thresholds of stimulated Raman scattering (SRS) in inhomogeneous plasmas is constructed based on the Fourier-space method. The model is valid for arbitrary density profiles and scattering geometries, including both backscattering and side scattering. It is shown that 90 deg side scatter has a lower absolute threshold than other scattering geometries. Backscatter, on the other hand, has a relatively large absolute threshold under conventional direct-drive ignition conditions. For a parabolic density profile, the absolute threshold of backscatter decreases dramatically at the peak of parabola, but is still much larger than that of side scatter. We also discuss the absolute thresholds of side scatter under different density profiles, showing not big differences with the linear density profile as well as the analytic formulas. Convective gains, however, are sensitive to the density profiles and collisional damping. The k-space numerical model is verified via analytic formulas and real-space envelope model, and it offers us new perspective on the scattering angles compared with previous models for SRS.

Clustering of spermatozoa examined through flow cytometry provides more information than the conventional assessment: a resilience to osmotic stress example.

Context Conventional sperm quality tests may not be sufficient to predict the fertilising ability of a given ejaculate; thus, rapid, reliable and sensitive tests are necessary to measure sperm function. Aims This study sought to address whether a cluster analysis approach based on flow cytometry variables could provide more information about sperm function. Methods Spermatozoa were exposed to either isotonic (300mOsm/kg) or hypotonic (180mOsm/kg) media for 5 and 20min, and were then stained with SYBR14 and propidium iodide (PI). Based on flow cytometry dot plots, spermatozoa were classified as either viable (SYBR14+ /PI- ) or with different degrees of plasma membrane alteration (SYBR14+ /PI+ and SYBR14- /PI+ ). Moreover, individual values of electronic volume (EV), side scattering (SS), green (FL1) and red (FL3) fluorescence were recorded and used to classify sperm cells through cluster analysis. Two strategies of this approach were run. The first one was based on EV and the FL3/FL1 quotient, and the second was based on EV, SS and the FL3/FL1 quotient. Key results The two strategies led to the identification of more than three sperm populations. In the first strategy, EV did not differ between membrane-intact and membrane-damaged sperm, but it was significantly (P P P Conclusions Cluster analysis based on flow cytometry variables provides more information about sperm function than conventional assessment does. Implications Combining flow cytometry with cluster analysis is a more robust approach for sperm evaluation.

BISTATIC SCATTERING CHARACTERISTICS OF A WIND PARK TURBINE DERIVED FROM AN UAV-MOUNTED RECEIVER RECORDING C-BAND WEATHER RADAR SIGNALS

Abstract. As a result of increasing use of wind energy as a sustainable source of electricity, large Wind Parks with numerous Wind Turbines have been constructed. Wind turbines are extremely tall objects consisting of stationary and moving parts. The presence of wind turbines in the vicinity of weather radar systems can significantly impact their performance, leading to false alarms and errors in radar measurements. Accurate weather forecasting is challenging in this circumstance. Large Radar Cross Section (RCS) of wind turbines results in interference, also known asWind Turbine Clutter (WTC) orWind Turbine Interference (WTI), within and beyond the radar main beam, Multipath Interference (MPI), and phenomena referred to as ”shadowing effects” behind the wind turbines. These effects vary significantly in both time and space as a result of various wind turbine operations and meteorological conditions. It can often be difficult to distinguish wind turbine returns from weather-like signals. For the assessment of WTC or WTI, it is essential to understand the scattering properties of these wind turbines. In this paper, the bistatic scattering characteristics of a wind park turbine using a Unmanned Aerial Vehicle (UAV)-mounted receiver recording C-band weather radar signals were investigated by determining the average received power (PRxAvg (θs)) and RCS of wind turbine as a function of the scattering angle. For this purpose, the measurements and data provided by the German Meteorological Service (DWD, DeutscherWetterdienst) were utilised. The average received power as a function of scattering angle (θs) was calculated by using I-Q (In-phase and Quadrature) signals. Forward, back and side scattering of the calculated average received power were analysed separately. Moreover, Front-to-Back ratio, Front-to-Right side ratio and Front-to-Left side ratio were calculated and compared using forward, back and side scatter values. RCS values were also calculated depending on the scattering angle (θs) of the wind turbine.

Evaluating the importance of Raman and Brillouin side scattering at ignition conditions

A complete linear model for Raman and Brillouin side scattering is analyzed with infinite and finite boundary conditions. Analytic formulas of absolute thresholds and convective gains for side scatterings are derived when infinite boundary is assumed. Finite beam width introduces finite boundary conditions to the side scattering, which could influence both absolute thresholds and convective gains. Using these formulas and models, we have evaluated the importance of stimulated Raman side scattering and stimulated Brillouin side scattering at ignition conditions, including both direct drive and indirect drive. It shows that side scattering could be a possible way of scattering other than backscattering in several ignition situations.

Identification of stimulated Raman side scattering in near-spherical coronal plasmas on OMEGA EP

Recent spherical-target laser–plasma interaction experiments, performed on the OMEGA EP laser, have been analyzed for stimulated Raman scattering (SRS). This has been motivated by results obtained on the National Ignition Facility (NIF) that have demonstrated the importance of SRS, and in particular SRS side scatter, for directly driven inertial confinement fusion (ICF) conditions [Rosenberg et al. Phys. Rev. Lett. 120, 055001 (2018); Michel et al. Phys. Rev. E 99, 033203 (2019)]. The analysis, based on a generalized ray tracing approach, is described and is shown to explain the observed scattered light spectra: it identifies SRS convective scattering, from portions of each incident beam where the scattered electromagnetic wave is generated in the direction parallel to contours of constant density, as the dominant contribution. This result is novel, as SRS is mostly associated with plasmas of higher electron temperature (Te≳3−4 keV) and longer density scale length (≳600 μm) than those considered here (Te∼1−3 keV, Ln∼150 μm) for the relevant overlapped irradiation intensities I≲1015 W/cm2. A combination of the high single-beam intensity on OMEGA EP and the side-scattering geometry, that has been identified, is responsible for this result. It is further suggested that the OMEGA EP platform could provide a good surrogate in which to develop SRS mitigation strategies.

Quantitative Estimation of Cell-Associated Silver Nanoparticles using the Normalized Side Scattering Intensities of Flow Cytometry.

Quantification of cellular nanoparticles (NPs) is one of the most important steps in studying NP–cell interactions. Here, a simple method for the estimation of cell-associated silver (Ag) NPs in lung cancer cells (A549) is proposed based on their side scattering (SSC) intensities measured by flow cytometry (FCM). To estimate cellular Ag NPs associated with A549 cells over a broad range of experimental conditions, we measured the normalized SSC intensities (nSSC) of A549 cells treated with Ag NPs with five different core sizes (i.e., 40–200 nm, positively charged) under various exposure conditions that reflect different situations of agglomeration, diffusion, and sedimentation in cell culture media, such as upright and inverted configurations with different media heights. Then, we correlated these nSSC values with the numbers of cellular Ag NPs determined by inductively coupled plasma mass spectrometry (ICPMS) as a well-established cross-validation method. The different core sizes of Ag NPs and the various exposure conditions tested in this study confirmed that the FCM-SSC intensities are highly correlated with their core sizes as well as the amount of cellular Ag NPs over a linear range up to ~80,000 Ag NPs/cell and ~23 nSSC, which is significantly broader than those of previous studies.

浑浊介质中激光侧向散射实验与仿真研究

浑浊介质中激光侧向散射实验与仿真研究

浑浊介质中激光侧向散射实验与仿真研究

浑浊介质中激光侧向散射实验与仿真研究

Unique Calibrators Derived from Fluorescence-Activated Nanoparticle Sorting for Flow Cytometric Size Estimation of Artificial Vesicles: Possibilities and Limitations.

The use of high-throughput flow cytometry to characterize nanoparticles has received increased interest in recent years. However, to fully realize the potential of flow cytometry for the characterization of nanometer-sized objects, suitable calibrators for size estimation must be developed and the sensitivity of conventional flow cytometers has to be advanced. Based on the scattered signal, silica and plastic beads have often been used as flow cytometric size calibrators to evaluate the size of extracellular vesicles and artificial vesicles (liposomes). However, several studies have shown that these beads are unable to accurately correlate scatter intensity to vesicle size. In this work, we present a novel method to estimate the size of individual liposomes in flow cytometry based on liposomal size calibrators prepared by fluorescence-activated cell sorting (FACS), here coined fluorescence-activated nanoparticle sorting (FANS). These calibration liposomes exhibit sizes, structures, and refractive indexes identical to the particles being studied and thus can serve as unique calibrators. First, a sample of polydisperse fluorophore-labeled unilamellar liposomes was prepared and analyzed by flow cytometry. Next, different fractions of the polydisperse liposomes were FANS-sorted according to their fluorescence intensity. Thereafter, we employed nanoparticle tracking analysis (NTA) to evaluate the liposome sizes of the FANS-sorted liposome fractions. Finally, we correlated the flow cytometric readouts (side scatter and fluorescence intensity) of the FANS-sorted liposome fractions with their corresponding size obtained by NTA. This procedure enabled us to translate the liposome fluorescence intensity to the liposome size in nanometers for all detected individual liposomes. We validated the size distribution of our polydisperse liposome sample obtained from flow cytometry in combination with our FANS-calibrators against standard methods for sizing nanoparticles, including NTA and cryo-transmission electron microscopy. This work also highlights the limitation of using the flow cytometric side scattering readout to determine the size of small (30-300 nm) artificial vesicles. © 2019 International Society for Advancement of Cytometry.

Automatic Classification of Label-Free Cells from Small Cell Lung Cancer and Poorly Differentiated Lung Adenocarcinoma with 2D Light Scattering Static Cytometry and Machine Learning.

Small cell lung cancer (SCLC) needs to be classified from poorly differentiated lung adenocarcinoma (PDLAC) for appropriate treatment of lung cancer patients. Currently, the classification is achieved by experienced clinicians, radiologists and pathologists based on subjective and qualitative analysis of imaging, cytological and immunohistochemical (IHC) features. Label-free classification of lung cancer cell lines is developed here by using two-dimensional (2D) light scattering static cytometric technique. Measurements of scattered light at forward scattering (FSC) and side scattering (SSC) by using conventional cytometry show that SCLC cells are overlapped with PDLAC cells. However, our 2D light scattering static cytometer reveals remarkable differences between the 2D light scattering patterns of SCLC cell lines (H209 and H69) and PDLAC cell line (SK-LU-1). By adopting support vector machine (SVM) classifier with leave-one-out cross-validation (LOO-CV), SCLC and PDLAC cells are automatically classified with an accuracy of 99.87%. Our label-free 2D light scattering static cytometer may serve as a new, accurate, and easy-to-use method for the automatic classification of SCLC and PDLAC cells. © 2018 International Society for Advancement of Cytometry.

Light-Scattering Sizing of Single Submicron Particles by High-Sensitivity Flow Cytometry.

Rapid and reliable size measurement of single submicron particles (100-1000 nm) is important for quality control of particulate matter, biomedical research, environmental study, and drug delivery system development. Though direct measurement of the elastically scattered light from individual submicron particles represents the simplest method for particle size measurement, the inadequate instrument sensitivity and complicated relationship between scattering intensity and particle size render it a great challenge. Combining the superior sensitivity of a laboratory-built high-sensitivity flow cytometer (HSFCM) in the side scattering (SSC) detection of single nanoparticles and the great efforts in synthesizing 38 highly monodisperse silica spheres ranging from 180 to 880 nm with small size intervals, here we report the first comprehensive comparison between the experimentally measured and Mie theory calculated intensities of light scattered by single submicron particles. Good agreements were observed for both the silica spheres and polystyrene beads at both the perpendicular and the parallel polarizations of the incident laser beam. Compared with perpendicular polarization, parallel polarization can resolve differently sized beads better due to the continuously increased scattering intensity with particle size. The predictive capability of the simple numerical model constructed in present work can be exploited to allow us to foresee scattering behavior on flow cytometers. More importantly, the linear correlation between the measured and the calculated scattering intensities enables us to develop a method that can measure the particle size of submicron particles with the precision and accuracy of Mie theory rather than a calibration curve fitted by several sparsely separated size reference standards. Comparable sizing resolution and accuracy to those of electron microscopy were demonstrated for Gram-positive bacteria Staphylococcus aureus. The as-developed method shows great potential in guiding the accurate size measurement of submicron particles.

Flow Cytometric Analysis of Protein Aggregates.

Misfolding of proteins often leads to aggregation. Accumulation of diverse protein aggregates in various cells, tissue and organs is the hallmark of many diseases, such as Alzheimer's disease and Parkinson's disease. The main objective of this study was to present a novel method of characterization of protein aggregates, associated with differential toxicity with different size and composition in vitro using flow cytometry. A Beckman Coulter Epics XL flow cytometer with argon ion laser operating at 488 nm was used for flow cytometry analysis. The voltage and the gain settings for individual channels were set at high voltage and gain for the detections of autofluorescence, fluorescence of adsorbed Congo red, forward scattering (FSC) and side scattering (SSC) intensities from the aggregates of proteins and nanoparticles. Each sample was analyzed to characterize and quantify the number of aggregates with a limit of maximum 20,000 events. The flow cytometry data were analyzed using Flowing software version 2.5.1 and Origin 8.0. Autofluorescence and scattering intensities could distinguish between amyloid and nonamyloid aggregates. Dot plots of both side scattering (SSC) and forward scattering (FSC) intensities also showed characteristic fingerprint of both the types of aggregates when compared with those of well known nanoparticles of oxides of Fe and Cu. This work reports a novel, simple and robust flow cytometric method of characterization of protein aggregates of different size and composition which would find wider application in characterization of biomolecular aggregates, in general.

Flow Cytometry-Based Quantification of Cellular Au Nanoparticles.

There has been a great deal of research regarding the cellular association of nanoparticles (NPs), although there are only a few methods available yet for the quantitative measurements of cellular NPs. In this study, we propose a simple and quantitative method to estimate the cellular uptake of Au NPs into cervical cancer cells (HeLa) based on their side scattering (SSC) intensities measured by flow cytometry (FCM). We have compared SSC intensities of HeLa cells exposed to eight different types of Au NPs (40-100 nm size, with positive or negative surface charge) with the amount of cellular Au NPs measured by inductively coupled plasma mass spectrometry (ICPMS). On the basis of these comparisons, we have found linear correlations between the cellular Au NPs and the SSC intensities and used them to estimate the amount of Au NPs associated with HeLa cells. Once the correlations were found for specific cell lines and types of nanoparticles, this approach is useful for simple and quantitative estimation of the cellular Au NPs, without performing labor-intensive and complicated sample preparation procedures required for the ICPMS approach.

A liposome‐based size calibration method for measuring microvesicles by flow cytometry

ESSENTIALS: A gold standard to determine the sizes of microvesicles by flow cytometry is needed. We used fluorescently labeled liposomes to estimate the size of microvesicles with flow cytometry. We suggest that liposomes are more accurate size calibrators than the commonly used polystyrene beads. The liposome-based size calibrators improve the size assessment of microvesicle made with flow cytometry. During the past years, the need for a gold standard to determine the sizes of extracellular vesicles including microvesicles by flow cytometry has been emphasized. This work suggests that artificial vesicles can be used as calibrators to estimate the size of microvesicles from the side scattering (SSC) measured with flow cytometry. We prepared fluorescently labeled liposomes with different maximum sizes defined by the pore size (200, 400, 800, and 1000 nm) of the membrane used for the extrusion. The fluorescence strengths from the largest liposomes pertaining to each pore size enabled us to verify the correlation between the SSC from a liposome and the corresponding size. This study indicates that artificial vesicles are more accurate size calibrators compared to the commonly used polystyrene calibrator beads illustrated by the SSC from 110 nm polystyrene beads corresponds to the scattering from ~400 nm vesicle-like particles. We also show that this method of size assessment based on SSC has a low resolution that is roughly estimated to be between 60 and 200 nm, dependent on the vesicle size.

Optical side scattering radiometry for high resolution, wide dynamic range longitudinal assessment of optical fibers.

Current optical reflectometric techniques used to characterize optical fibers have to trade-off longitudinal range with spatial resolution and therefore struggle to provide simultaneously wide dynamic range (>20dB) and high resolution (<10cm). In this work, we develop and present a technique we refer to as Optical Side Scattering Radiometry (OSSR) capable of resolving discrete and distributed scattering properties of fibers along their length with up to 60dB dynamic range and 5cm spatial resolution. Our setup is first validated on a standard single mode telecoms fiber. Then we apply it to a record-length 11km hollow core photonic band-gap fiber (HC-PBGF) the characterization requirements of which lie far beyond the capability of standard optical reflectometric instruments. We next demonstrate use of the technique to investigate and explain the unusually high loss observed in another HC-PBGF and finally demonstrate its flexibility by measuring a HC-PBGF operating at a wavelength of 2µm. In all of these examples, good agreement between the OSSR measurements and other well-established (but more limited) characterization methods, i.e. cutback loss and OTDR, was obtained.

Unidirectional Side Scattering of Light by a Single-Element Nanoantenna

Unidirectional side scattering of light by a single-element plasmonic nanoantenna is demonstrated using full-field simulations and back focal plane measurements. We show that the phase and amplitude matching that occurs at the Fano interference between two localized surface plasmon modes in a V-shaped nanoparticle lies at the origin of this effect. A detailed analysis of the V-antenna modeled as a system of two coherent point-dipole sources elucidates the mechanisms that give rise to a tunable experimental directivity as large as 15 dB. The understanding of Fano-based directional scattering opens a way to develop new directional optical antennas for subwavelength color routing and self-referenced directional sensing. In addition, the directionality of these nanoantennas can increase the detection efficiency of fluorescence and surface enhanced Raman scattering.

Novel Label-Free Cells Structure Detection Method Study Based on Mie Scattering Principle

Cell health situation relates to its inter structures closely. Cell scattering measurement can be a non-invasive measurement method to obtain cells structure information. But normal scattering detection by original scattering spectrum can not identify cells inner structure changing, such as nucleus radii difference. Traditional scattering spectrum analysis method for identifying cells is to plot the forward scattering (FS) light intensity against side scattering (SS) light intensity. Overlapping phenomenon always occurs which leads to serious error or even mistakes in cells identification results. The Novel even scattering angle superposition algorithm and even incident angle superposition algorithm are put forward herein. In this way, the same kind of cells with different inner structures can be effectively distinguished. The rapid, convenient and label-free cells assorting and detecting can be therefore well accomplished, and these novel methods could be a kind of important diagnostic tool in cancer or other malignant cells diagnosis.

Characterization of functionally distinct mitochondrial subpopulations

Mitochondrial stress results in changes in mitochondrial function, morphology and homeostasis (biogenesis, fission/fusion, mitophagy) and may lead to changes in mitochondrial subpopulations. While flow cytometric techniques have been developed to quantify features of individual mitochondria related to volume, Ca(2+) concentration, mtDNA content, respiratory capacity and oxidative damage, less information is available concerning the identification and characterization of mitochondrial subpopulations, particularly in epithelial cells. Mitochondria from rabbit kidneys were stained with molecular probes for cardiolipin content (nonyl acridine orange, NAO) and membrane potential (tetramethylrhodamine, TMRM) and analyzed using flow cytometry. We validated that side scatter was a better indicator of volume and that as side scatter (SSC) decreased mitochondrial volume increased. Furthermore, those mitochondria with the highest NAO content had greater side scattering and were most highly charged. Mitochondria with average NAO content were of average side scattering and maintained an intermediate charge. Those mitochondria with low NAO content had minimal side scattering and exhibited minimal charge. Upon titration with the uncoupler carbonylcyanide-4-(trifluoromethoxy)-phenylhydrazone (FCCP), it was found that the high NAO content subpopulations were more resistant to uncoupling than lower NAO content populations. Ca(2+)-induced swelling of mitochondria was evaluated using probability binning (PB) analyses of SSC. Interestingly, only 30% of the mitochondria showed changes in response to Ca(2+), which was blocked by cyclosporine A. In addition, the small, high NAO content mitochondria swelled differentially in response to Ca(2+) over time. Our results demonstrate that flow cytometry can be used to identify mitochondrial subpopulations based on high, mid and low NAO content and/or volume/complexity. These subpopulations showed differences in membrane potential, volume, and responses to uncoupling and Ca(2+)-induced swelling.

Correlating light scattering with internal cellular structures.

The origins of side scattering from a fibroblast and cervical cell line were determined by comparing side-scatter images with images stained for lysosomes, nuclei, and mitochondria on a cell by cell basis. Lysosomes or nuclei are the most efficient type of scatterer depending on the cell type and incident light polarization. The relative scattering efficiencies of lysosomes and mitochondria were the same for both cell lines, while the scattering efficiencies of the nuclei differed. The percent of 90° scattering from the nucleus, mitochondria, and lysosomes as well as the group of other internal cellular objects was estimated. The nucleus was the largest contributor to side scatter in the cervical carcinoma cells. The contributions of lysosomes, mitochondria, the nucleus, and particles unstained by either Hoechst, LysoSensor or MitoTracker ranges from ∼20% to ∼30% in fibroblast cells. The contribution of lysosomes to side scatter was much stronger when the incident light was polarized perpendicular to the scattering plane than when the polarization of the side scatter laser was parallel to the scattering plane. This dependence on side scatter polarization indicates that lysosomes contain scattering structures that are much smaller than the wavelength of light used in the measurements (785 nm). In conclusion, mitochondria were not found to be either the most efficient scatterer or to have the largest contribution to scattering in either cell line, in contrast to previous reports. Rather lysosomes, nuclei and unknown particles all have significant contributions to 90° scattering and the contributions of some of these particles can be modulated by changing the polarization of the incident light.

Increasing productivity of hybridoma cell lines by sorting by side scattering light

The side scattering light of a mammalian cell is caused, among other things, by the membranes of cell organelles. We suggest that cells with a high side scatter contain a large amount of mitochondria and a large endoplasmatic reticulum. In a simple approach we separate cells with a high side scatter via fluorescence activated cell sorting (FACS) to create sub populations with a higher productivity. We obtain cells with a high amount of mitochondria and a large endoplasmatic reticulum which could cause strong energy metabolism and high protein productivity. The advantage of this technique is that no staining dye or complex procedure is needed to reach the goal of increasing the productivity of a cell line.