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[Methods in Molecular Biology] BCL-2 Family Proteins Volume 1877 (Methods and Protocols) || Quantification of the Interactions Between BCL-2 Proteins by Fluorescence Correlation Spectroscopy
摘要： The proteins of the Bcl-2 family regulate apoptosis by forming a complex interaction network whose output determines whether mitochondrial outer membrane permeabilization is executed. Quanti?cation of complex formation between Bcl-2 proteins in solution and in membranes is therefore key to understand how the hierarchy of interactions controls cell death induction. Fluorescence correlation spectroscopy (FCS) is a noninvasive, nondestructive method to investigate the mobility and the association of ?uorescently labeled biomolecules that has provided useful insight into the binding af?nity of the Bcl-2 interactome. FCS is based on the detection of ?uorescence ?uctuations caused by the diffusion of individual molecules through a very tiny observation volume of the detection system. Scanning FCS (SFCS) solves some of the practical challenges of acquiring FCS in membranes and expands the application scope of the method. In this chapter, we explain the principle of FCS and describe protocols how it can be used to quantify interactions between Bcl-2 proteins in solution and in model membrane systems.
关键词： FCCS,Scanning FCCS,Bcl-xL,cBid,Bcl-2,Fluorescence correlation spectroscopy,FCS,Bax
更新于2025-11-21 11:08:18
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Diffusion Behavior of Differently Charged Molecules in Self-Assembled Organic Nanotubes Studied Using Imaging Fluorescence Correlation Spectroscopy
摘要： The diffusion behavior of fluorescent molecules within bolaamphiphile-based organic nanotubes (ONTs) was systematically investigated using imaging fluorescence correlation spectroscopy (imaging FCS). Anionic sulforhodamine B (SRB), zwitterionic/cationic rhodamine B (RB) or cationic rhodamine 123 (R123) was loaded into ONTs having cylindrical hollow structures (ca. 10 nm in inner diameter) with amine and glucose groups on the inner and outer surfaces, respectively. Wide-field fluorescence video microscopy was used to acquire imaging FCS data for dye-doped ONTs in aqueous solutions of different ionic strengths (1 – 500 mM) at different pH (3.4 – 8.4). The diffusion behavior of these dyes was discussed on the basis of their apparent diffusion coefficients (D) that were determined by autocorrelating the time transient of fluorescence intensity at each pixel on an ONT. Molecular diffusion in the ONTs was significantly slowed by molecule-nanotube interactions, as shown by the very small D (10-1 – 10-2 μm2/s). The pH-dependence of D revealed that dye diffusion was basically controlled by electrostatic interactions associated with the protonation of the amine groups on the ONT inner surface. The pH-dependent change in D was observed over a wide pH range, possibly due to electrostatically induced variations in the pKa of the densely packed ammonium ions on the ONT inner surface. On the other hand, the influence of ionic strength on D was relatively unclear, suggesting the involvement of non-coulombic interactions with the ONTs in molecular diffusion. Importantly, individual ONTs of different lengths (1 – 5 μm) afforded similar diffusion coefficients for each type of dye at each solution condition, implying that the properties of ONTs were uniform in terms of solute loading and release. These results highlight the characteristics of molecular diffusion behavior within the ONTs, and will help in the design of organic nanotubes better suited for use as drug vehicles and contaminant adsorbents.
关键词： Electrostatic Interactions,Diffusion Behavior,Ionic Strength,pH-dependence,Imaging Fluorescence Correlation Spectroscopy,Organic Nanotubes
更新于2025-11-19 16:56:42
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Plastic anisotropy of laser melting deposited Ti–5Al–5Mo–5V–1Cr–1Fe titanium alloy
摘要： Tensile tests of laser melting deposited Ti–5Al–5Mo–5V–1Cr–1Fe titanium alloy specimens in different orientations were conducted, which indicates significant plastic anisotropy of this material. Digital image correlation method added in-situ-tensile tests were carried out to investigate mechanical properties with respect to specified material structures. The results indicate that the plasticity properties of the thick columnar grain and that of other grains are significant different. Under the same stress level, the thick columnar grain yield firstly and bear the main plastic deformation of the whole specimen. The elasto-plastic Poisson's ratio of the thick columnar grains and that of other grains are also different. Tests on layer bands indicate that the coarser microstructures of the layer bands lead a stronger resistance to tensile plastic deformation, but a weaker resistance to shear plastic deformation. In addition, the direction of primary α laths on both sides of the layer bands may be different, and this has an obviously effect on the tensile plastic deformation of the specimen.
关键词： Digital image correlation method,Plastic anisotropy,Laser melting deposited,Titanium alloy,Mechanical properties
更新于2025-10-24 16:40:20
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Performance Limits of FSO Based SAC-OCDMA System Under Weather Conditions
摘要： In this paper, the Spectral Amplitude Coding Optical Code Division Multiple Access (SAC-OCDMA) is investigated in Free Space Optics (FSO) using Zero Cross Correlation (ZCC) codes to evaluate its performance limits in terms of link range. The system is analyzed under clear, haze, moderate fog and dense fog weather conditions. This system has been evaluated numerically and by simulation analysis by maintaining the transmitted power at 10 dBm, for safety reason, according to International Telecommunication Union (ITU) and minimum acceptable BER of 10–9. The simulation results shown that the present system can transmit 622 Mbps/1 Gbps up to maximum link range of 1450 m/1100 m and 61 m/54 m under clear and dense fog conditions, respectively.
关键词： fog,haze,free space optic (FSO),spectral amplitude coding optical code division multiple access (SAC-OCDMA),zero cross-correlation (ZCC)
更新于2025-09-23 15:23:52
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Linear complex susceptibility of long-range interacting dipoles with thermal agitation and weak external ac fields
摘要： An analytical formula for the linear complex susceptibility of dipolar assemblies subjected to thermal agitation, long-range interactions, and an externally applied uniform sinusoidal field of weak amplitude is derived using the forced rotational diffusion equation of Cugliandolo et al. [Phys. Rev. E 91, 032139 (2015)] in the virial approximation. If the Kirkwood correlation factor of the dipolar assembly gK exceeds unity, a thermally activated process arising from the interaction-specific component arises, while for gK < 1 the susceptibility spectrum normalized by its static value is practically unaltered with respect to that of the ideal gas phase.
关键词： long-range interactions,thermally activated process,dipolar assemblies,thermal agitation,Kirkwood correlation factor,linear complex susceptibility
更新于2025-09-23 15:23:52
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[IEEE 2017 International Conference on Current Trends in Computer, Electrical, Electronics and Communication (CTCEEC) - Mysore, India (2017.9.8-2017.9.9)] 2017 International Conference on Current Trends in Computer, Electrical, Electronics and Communication (CTCEEC) - An Approach of Abnormality Detection for Diabetic Retinopathy using ANN SVM
摘要： Glaucoma is the diagnosis given to a group of ocular conditions that contribute to the loss of retinal nerve fibers with a corresponding loss of vision. Glaucoma is the major cause of blindness in people above the age of 40. The Intra Ocular Pressure (IOP) increases because of the malfunction of the drainage structure of the eyes leading to Glaucoma. In this paper three methods-Gray Level Difference Method using ANN classifier, Stochastic watershed method using SVM classifier and Pearson R Correlation Method are proposed, which automatically detect Glaucoma disease in the human eye from the fundus database images. The three strategies utilized for retinal abnormality identification are looked at in light of the execution measurements- exactness and blunder rate. The SVM classifier gives more precise outcomes contrasted with other two procedures.
关键词： Stochastic Watershed,GLDM feature extraction,Pearson R Correlation
更新于2025-09-23 15:23:52
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Real-time detection of moving cast shadows using foreground luminance statistics
摘要： This paper presents a robust real-time method for detection of moving cast shadows which employs the assumption of higher interdependence of luminance values for the shadow pixels in larger regions compared to the object pixels. First, a fast modified image differencing technique is used to separate foreground pixels from the background. Next, for a moving window of fixed width scanning the foreground regions, a new measure called Modified Correlation is introduced. The new measure is determined by first computing the correlation between the luminance values of the moving window and luminance values of its neighbouring windows; this correlation is then divided by a robust-to-noise range measured based on the luminance values of the moving window. The modified correlation exhibits abrupt rising transitions as it enters the shadow region from the object region, transitions which can be used to separate object pixels from shadow pixels. Thus, the new method is very effective at suppressing moving cast shadows, while avoiding limiting structures, unrealistic assumptions, the need for a-priori knowledge, and manual selection of critical parameters. An average shadow detection rate of 85.4% and an average shadow discrimination rate of 99.5% over multiple different sequences, higher than those of available methods in the literature, confirm the efficacy of the method. The robustness of the method is examined under different lighting conditions, different target-environment combinations, and sequences with object-shadow occlusion. The proposed method is computationally efficient and suitable for real-time situations.
关键词： Moving cast shadow,Image difference,Correlation,Sliding window,Foreground mask,Real-time detection
更新于2025-09-23 15:23:52
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Nonclassical properties of two-mode squeezing-enhanced vacuum state
摘要： We present a new kind of two-mode squeezed vacuum state with two squeezing parameters. Different from the normal univariate two-mode squeezed vacuum state, this new state shows stronger squeezing effect, anti-bunching and entanglement. It is shown that the new squeezing parameter plays an important role in this state.
关键词： fidelity,entanglement,cross-correlation function,squeezing,antibunching effect
更新于2025-09-23 15:23:52
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An omnidirectional DIC system for dynamic strain measurements on soft biological parts to An omnidirectional DIC system for dynamic strain measurement on soft biological tissues and organs
摘要： A limitation to the potential use of inverse methods in identifying the spatially varying properties of biological tissues consists in obtaining the required set of experimental data. In fact, whereas on the numerical side there are almost no limits to complexity in terms of geometry and material behavior of the model, on the experimental side, the collection of full-field displacement and strain data over the full surface of complex 3D geometries still represents a challenge. To address this issue, this work proposes an omnidirectional-DIC method capable of obtaining full-field information over the entire surface of native intact biological parts undergoing large deformation. This is made possible by the use of a concave conical mirror that enlarges the field of view of a conventional binocular stereo-DIC system up to 360° × 320°. The pair of highly distorted panoramic scenes reflected by the conical mirror are then matched by using a novel iterative image deformation scheme. In particular, first, a robust feature-based algorithm is used to calculate the gross disparity between images, then, an iterative NURBS-based intensity interpolation scheme refines the correlation through a hybrid local-global DIC approach. The accuracy of the developed image matching scheme was evaluated on synthetically generated images simulating a large and heterogeneous deformation field. Then, the potential of the proposed omnidirectional-DIC method was tested with rubber analogs reproducing the most representative geometries and loading states involved in biological materials characterization. Finally, as an illustrative example of application, full-field DIC shape and deformation measurements was performed over a whole porcine eye tested in-vitro under reproduced physiological load.
关键词： Eye,Omnidirectional measurement,Finite deformation,Digital image correlation,Inflation test
更新于2025-09-23 15:23:52
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Study on sliding-window length based on Rayleigh backscattering spectrum correlation in distributed optical-fiber strain measurement
摘要： A theoretical model is established for estimating the strain measurement error based on the Rayleigh backscattering spectrum correlation in distributed optical fiber strain measurements. Assuming the signal is much larger than the noise, the theoretical model predicts the strain measurement error using noise variance and the defined quality factor Q of the Rayleigh backscattering spectrum. Furthermore, an algorithm based on the quality factor Q is proposed to select an optimized sliding-window. The sliding-window length can be obtained by calculating the threshold value of the quality factor using a theoretical model corresponding to the required strain measurement accuracy. Compared with the traditional method where the sliding-window length is defined by the user based on spatial resolution requirements or an empirical definition, the sliding-window length determined by the algorithm is more reasonable and can be automatically defined, alleviating the requirement for user inputs. To verify the correctness of the theoretical model, two experiments are set up: a self-correlation experiment, that analyzes the effect of the quality factor on the strain measurement accuracy, and a virtual experiment of the noise influence, which analyzes the effect of different noise variances. The experimental results are in good agreement with those of the model.
关键词： Distributed optical fiber strain measurement,Rayleigh backscattering spectrum correlation,Optical frequency domain reflectometer
更新于2025-09-23 15:23:52