Diffraction Intensity Patterns Research Articles

Biosynthesis of antimicrobial nanoparticle from Swertia spp. (Chirayita) against bacterial pathogens of poultry- A way forward to green nanotechnology and nano-medicines

The increasing prevalence of multidrug-resistant microorganisms in poultry has led to a rise in bacterial infections, causing significant economic loss. Green nanotechnology, such as silver nanoparticles (AgNPs), has the potential to address this issue by providing potent antifungal, antiviral, and antibacterial properties. This study explored the combined potential of AgNPs and the local herb Swertia chirayita against established poultry pathogens, employing a non-factorial Central Composite Design (CCD) to evaluate the factors affecting the production of nanoparticles induced by silver nitrate from the selected herb. The optimal values for temperature, wavelength, silver nitrate concentration, incubation duration, and pH were found to produce the highest nanoparticles. The functional groups in Swertia chirayita stimulated nanoparticles were confirmed using FTIR spectroscopy, and the stability of ScNPs was elucidated using zeta potential. The crystalline structure of ScNPs was confirmed using diffraction intensity patterns. Silver nanoparticles demonstrated antibacterial activity against Salmonella spp. and Escherichia coli (E.coli), both known as significant poultry pathogens, using the agar well diffusion method, with inhibition zones of 25.0 mm and 35.0 mm, respectively.This study explored the green manufacturing of silver nanoparticles by using plants and microorganisms, focusing on their antibacterial properties. The exact mechanism of synthesis and action in AgNPs is still poorly understood. Researchers should prioritize the use of accessible, easy-to-extract plants or bacteria, especially non-pathogenic and fast-growing microorganisms for safe handling. Analyzing biomolecules in plant extract, microbial biomass, or culture supernatants, including probiotic bacteria, is crucial for creating and stabilizing AgNPs, which could be effective synthetic agents. It is crucial to optimize conditions for rapid, stable, and large-scale synthesis. Based on this research, Sc-NPs may be proposed as nanomedicine for treating infections in poultry caused by E. coli and Salmonella spp.

Phase retrieval from a single diffraction intensity pattern by generating the support constraint using deep learning

Phase retrieval is an essential technique for imaging applications in many fields such as biology and materials science. The fundamental challenge lies in reconstructing objects from measured intensity patterns. A prevalent solution involves an iterative strategy that alternates projections between the object and detector planes. However, reconstructing objects from a single diffraction intensity pattern remains challenging due to the absence of constraints at the object plane. Here, we propose a learning-based approach that generates reliable object support in real time from its autocorrelation support. With the generated support as the constraint for the object plane, we show that the convergence of iterative phase retrieval algorithms can be markedly enhanced. Compared with the end-to-end learning-based methods, the proposed method has a unique character that the training features are binary supports, instead of the type and content of objects, so that our approach has better generalization. Furthermore, one of the advantages of our method is that it uses simulated data for training, eliminating the need for experimental data collection.

Ptychographic lensless coherent endomicroscopy through a flexible fiber bundle

Conventional fiber-bundle-based endoscopes allow minimally invasive imaging through flexible multi-core fiber (MCF) bundles by placing a miniature lens at the distal tip and using each core as an imaging pixel. In recent years, lensless imaging through MCFs was made possible by correcting the core-to-core phase distortions pre-measured in a calibration procedure. However, temporally varying wavefront distortions, for instance, due to dynamic fiber bending, pose a challenge for such approaches. Here, we demonstrate a coherent lensless imaging technique based on intensity-only measurements insensitive to core-to-core phase distortions. We leverage a ptychographic reconstruction algorithm to retrieve the phase and amplitude profiles of reflective objects placed at a distance from the fiber tip, using as input a set of diffracted intensity patterns reflected from the object when the illumination is scanned over the MCF cores. Our approach thus utilizes an acquisition process equivalent to confocal microendoscopy, only replacing the single detector with a camera.

Low-cost single-shot complex optical field imaging with a simplified aperture

We report a new computational imaging methodology for complex optical field based on a single-frame diffraction intensity pattern acquisition with a simplified aperture and an extremely low-cost industrial machine vision camera. The current design of the apertures for the recovery of complex optical field was suffering from specific coding associated with the use of spatial light modulator or digital micromirror device, where it is difficult to make the optical implementations compact and cost-effective. In this work, we demonstrate that a simplified aperture without any pattern-like coding is efficient to establish the physical constraint for computational reconstruction. The aperture attached to the object defines the imaging region of interest (ROI) with coherent trans-illumination, and only one snapshot of the diffraction intensity pattern is required for recovering the ROI's complex field. Proof-of-concept numerical simulations and optical experiments have been carried out to validate the feasibility, noise robustness, resolution, and potential biological imaging applications of the proposed computational method.

Demonstration of Helide formation for fusion structural materials as natural lattice sinks for helium

Fusion power holds promise as an ultimate energy source. However, achieving true sustainability in fusion energy requires addressing the embrittlement of polycrystalline materials in fusion reactors caused by helium, which leads to premature failure, often within a year. Here we experimentally demonstrate that nanodispersoids with constitutional vacancy-like atomic-scale free volume can securely store helium, not only at the matrix-dispersoid interface but also within their bulk lattices, which suggests their effectiveness in delaying critical helium damage of the polycrystalline matrix. The selected model nano-heterophase, fayalite Fe2SiO4, possesses moderately strong lattice sinks for helium while undergoing lattice distortions upon helium absorption. These distortions cause observable changes in peak intensities of X-ray diffraction (XRD) patterns, distinct from changes resulting from other factors like radiation damage. By comparing grazing incidence XRD patterns with ab initio computed patterns, we show that such nano-heterophases can store up to ∼10 at% helium within their bulk lattice, forming a “helide compound.” Incorporating just 1 vol% of Fe2SiO4 reduces helium bubble size and number density by >20 % and >50 %, respectively. These findings suggest that 1–2 vol% of appropriate nano-heterophases can accommodate a few thousand appm of bulk helium, expected to be generated over a 10-year operational period.

Microwave assisted synthesis of ZnIn2S4 nanoparticles: effect of power variation for photoresponse and optoelectronic applications.

The ternary ZnIn2S4 has recently gained significant attention due to its potential applications in various optoelectronics and photocatalysis sectors. In the current study, ZnIn2S4 nanoparticles were prepared using a simple microwave-assisted synthesis method with different irradiation powers varying from 180 W-720 W. Structural analysis confirmed their polycrystalline nature with the appearance of ZnIn2S4 and In2S3 phases. The variation in diffraction pattern intensity and Raman vibrational bands with irradiation power indicates structural rearrangements induced with power variation. Morphological studies confirmed the formation of agglomerate nanoparticles with size variation as induced by different microwave powers. Broad absorption across the visible and near-infrared regions and the increased band gap enhance their photocatalytic and sensing applications. An increased irradiation power in the ZnIn2S4 lattice reduced intermediate levels within the band gap, altering the optical responsiveness. The blue shift in absorption edges with microwave power increased the optical band gap by reducing disorder and defects. The refractive indices were estimated using different theoretical models and reduced with an increase in the band gap. Thermal analysis revealed endothermic peaks. These ZnIn2S4 nanoparticles displayed an enhanced photocurrent under white light, increasing tenfold with microwave power. The greater powered ZIS (ZIS-720 W) nanomaterial showed the best photoresponse and is well suited for optoelectronic application. All of their optical and electrical properties make them suitable for various optoelectronic devices, particularly in detection applications.

On the origin of diffuse intensities in fcc electron diffraction patterns.

Interpreting diffuse intensities in electron diffraction patterns can be challenging in samples with high atomic-level complexity, as often is the case with multi-principal element alloys. For example, diffuse intensities in electron diffraction patterns from simple face-centred cubic (fcc) and related alloys have been attributed to short-range order1, medium-range order2 or a variety of different {111} planar defects, including thin twins3, thin hexagonal close-packed layers4, relrod spiking5 and incomplete ABC stacking6. Here we demonstrate that many of these diffuse intensities, including [Formula: see text]{422} and [Formula: see text]{311} in ⟨111⟩ and ⟨112⟩ selected area diffraction patterns, respectively, are due to reflections from higher-order Laue zones. We show similar features along many different zone axes in a wide range of simple fcc materials, including CdTe, pure Ni and pure Al. Using electron diffraction theory, we explain these intensities and show that our calculated intensities of projected higher-order Laue zone reflections as a function of deviation from their Bragg conditions match well with the observed intensities, proving that these intensities are universal in these fcc materials. Finally, we provide a framework for determining the nature and location of diffuse intensities that could indicate the presence of short-range order or medium-range order.

Effect of Heat Treatment on Microstructure and Mechanical Properties of Medium-Carbon Steel Drawn Wire

<div>In this article, the effect of heat treatment on the microstructure and mechanical behavior of medium-carbon steel wire intended for the spring mattress is investigated using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), X-ray diffraction, Vickers hardness (Hv), and tensile strength. The results indicate that the microstructure elongation along the wire axis is observed with the bending and kinking lamellae at the deformation level of 57.81%, this change appears as a fracture in the microstructure and leads to an increase in hardness, tensile strength, and intensities of diffraction patterns. After heat treatment, we observed a redistribution in the grain, which is almost the same in the wire rod and drawn wires; indeed, this led to a decrease in hardness, tensile strength, and augmentation in intensities of peaks. The EBSD pole figures reveal the development of texture in the cementite slip plane (001).</div>

Detection of topological charge for composite perfect vortex beams in atmospheric turbulence

Aiming at the problem of detecting the orbital angular momentum (OAM) states of the composite perfect vortex beams (CPVBs) under atmospheric turbulence (AT) channels, we propose and investigate a joint scheme of combing an optical detection method and the Gerchberg-Saxton (GS) algorithm. We firstly used the GS algorithm to pre-compensate the distorted CPVBs, and then the optical intensity distribution, together with the far-field diffraction patterns of the CPVBs after they passing through an elliptical aperture which shields part of the azimuth angle (EA-shielded), can tell us the topological charges (TCs) carried by each sub beam. The results show that the tailing direction of the bright stripes in the CPVBs intensity distribution denotes the sign of the higerh-order TC, counterclockwise is positive, clockwise is negative. The difference between the TCs of the two beams is indicated by the number of stripes, that is, the number of stripes is equal to the absolute values of differences between the two beams. After passing through the EA-shielded, the far-field diffraction intensity patterns is related to the magnitude and sign of the lower-order TC. If the bright stripes are distributed above, the TC is positive, otherwise, the TC is negative, and the number of dark stripes is equal to the lower-order TC-1. The results provide a new method for detecting the TC information of the CPVBs after phase distortion.

Mapping Polar Distortions using Nanobeam Electron Diffraction and a Cepstral Approach.

Measuring local polar ordering is key to understanding ferroelectricity in thin films, especially for systems with small domains or significant disorder. Scanning nanobeam electron diffraction (NBED) provides an effective local probe of lattice parameters, local fields, polarization directions, and charge densities, which can be analyzed using a relatively low beam dose over large fields of view. However, quantitatively extracting the magnitudes and directions of polarization vectors from NBED remains challenging. Here, we use a cepstral approach, similar to a pair distribution function, to determine local polar displacements that drive ferroelectricity from NBED patterns. Because polar distortions generate asymmetry in the diffraction pattern intensity, we can efficiently recover the underlying displacements from the imaginary part of the cepstrum transform. We investigate the limits of this technique using analytical and simulated data and give experimental examples, achieving the order of 1.1 pm precision and mapping of polar displacements with nanometer resolution.

Visualization of molecular stacking using low-energy electron microscopy

The design of metal-organic interfaces with atomic precision enables the fabrication of highly efficient devices with tailored functionality. The possibility of fast and reliable analysis of molecular stacking order at the interface is of crucial importance, as the interfacial stacking order of molecules directly influences the quality and functionality of fabricated organic-based devices. Dark-field (DF) imaging using Low-Energy Electron Microscopy (LEEM) allows the visualization of areas with a specific structure or symmetry. However, distinguishing layers with different stacking orders featuring the same diffraction patterns becomes more complicated. Here we show that the top layer shift in organic molecular bilayers induces measurable differences in spot intensities of respective diffraction patterns that can be visualized in DF images. Scanning Tunneling Microscopy (STM) imaging of molecular bilayers allowed us to measure the shift directly and compare it with the diffraction data. We also provide a conceptual diffraction model based on the electron path differences, which qualitatively explains the observed phenomenon.

High-precision phase retrieval method for speckle suppression based on optimized modulation masks.

Traditional methods of coherent diffraction imaging using random masks result in an insufficient difference between the diffraction patterns, making it challenging to form a strong amplitude constraint, causing significant speckle noise in the measurement results. Hence, this study proposes an optimized mask design method combining random and Fresnel masks. Increasing the difference between diffraction intensity patterns enhances the amplitude constraint, suppresses the speckle noise effectively, and improves the phase recovery accuracy. The numerical distribution of the modulation masks is optimized by adjusting the combination ratio of the two mask modes. The simulation and physical experiments show that the reconstruction results of PSNR and SSIM using the proposed method are higher than those using random masks, and the speckle noises are effectively reduced.

Diffraction of a Laguerre-Gaussian beam in Raman interaction with a spatially periodic pump field

We studied Fresnel diffraction of a Laguerre-Gaussian beam ${\text{LG}}_{p,l}$ with arbitrary azimuthal $l$ and radial $p$ indices on a grating induced during its Raman interaction with a spatially periodic pump field in an atomic medium. The diffraction pattern turned out to be more complex than the classical Talbot effect observed when a plane wave illuminates a two-dimensional grating. The simulation results show that, under certain conditions, at distances corresponding to the classical Talbot planes (integer and fractional), periodic amplitude-phase distributions appear. The diffraction patterns are not a probe-field image in the induced grating plane, but a regular array of vortex annular-shaped microbeams with an inhomogeneous intensity distribution depending on the $l$ and $p$ indices and with a topological charge equal to that of the initial probe beam. The intensity and spatial distribution of diffraction patterns can be controlled by Raman amplification in the induced grating by varying the pump-field intensity or the Raman detuning.

Annular phase grating-assisted recording of an ultrahigh-order optical orbital angular momentum.

Ultrahigh-order optical orbital angular momentum (OAM) states of the identification over ±270 orders are implemented by annular phase grating (APG) and Gaussian beams with different wavelengths. Particularly, the far-field diffraction intensity patterns feature the spiral stripes instead of Hermitian-Gaussian (HG)-like fringes. It's worth noting that the spiral stripes present uniform distribution, thus the order of OAM states can be intuitively acquired. More specifically, the OAM states can be confirmed from the total amount and rotating direction of the spiral stripes. Compared with traditional methods, the propose scheme contributes to the perfect-distributed and sharper spiral stripes. Moreover, it also makes an easier observation of the patterns in the CCD camera with limited imaging targets. In our experimental setup, the optical filter is removed and the APG parameters are not strictly required. Therefore, the propose optical transmission system is equipped with the advantages of efficiency, robustness and low cost, which paves a promising way for the communication capacity enhancement.

The Effect of Lead Halide on Characterization of Methyl Ammonium Iodine MAI2 Perovskite

A hybrid method is proposed to synthesize methylammonium lead iodine, bromine and chlorine MAPbI3, MAPbBr2I and MAPbCl2I Perovskite by mixing two-step methods. The descriptions of perovskite samples included structural, morphological and optical properties. The intensity and orientation in X-ray diffraction (XRD) patterns appear clearly and squeaky. FESEM images of the perovskite films appeared as a rough surface due to iodine and more crystalline size using bromine and chlorine. Optical properties shifted towards low wavelengths (blue shift) and the value changed from 830 nm to 420 nm when the lead halide is changed from iodine to bromine and then to chlorine.

Mixed scale dense convolutional networks for x-ray phase contrast imaging

X-ray in-line phase contrast imaging relies on the measurement of Fresnel diffraction intensity patterns due to the phase shift and the attenuation induced by the object. The recovery of phase and attenuation from one or several diffraction patterns is a nonlinear ill-posed inverse problem. In this work, we propose supervised learning approaches using mixed scale dense (MS-D) convolutional neural networks to simultaneously retrieve the phase and the attenuation from x-ray phase contrast images. This network architecture uses dilated convolutions to capture features at different image scales and densely connects all feature maps. The long range information in images becomes quickly available, and greater receptive field size can be obtained without losing resolution. This network architecture seems to account for the effect of the Fresnel operator very efficiently. We train the networks using simulated data of objects consisting of either homogeneous components, characterized by a fixed ratio of the induced refractive phase shifts and attenuation, or heterogeneous components, consisting of various materials. We also train the networks in the image domain by applying a simple initial reconstruction using the adjoint of the Fréchet derivative. We compare the results obtained with the MS-D network to reconstructions using U-Net, another popular network architecture, as well as to reconstructions using the contrast transfer function method, a direct phase and attenuation retrieval method based on linearization of the direct problem. The networks are evaluated using simulated noisy data as well as images acquired at NanoMAX (MAX IV, Lund, Sweden). In all cases, large improvements of the reconstruction errors are obtained on simulated data compared to the linearized method. Moreover, on experimental data, the networks improve the reconstruction quantitatively, improving the low-frequency behavior and the resolution.

Investigation of Nonlinear Optical Properties of Quantum Dots Deposited onto a Sample Glass Using Time-Resolved Inline Digital Holography.

We report on the application of time-resolved inline digital holography in the study of the nonlinear optical properties of quantum dots deposited onto sample glass. The Fresnel diffraction patterns of the probe pulse due to noncollinear degenerate phase modulation induced by a femtosecond pump pulse were extracted from the set of inline digital holograms and analyzed. The absolute values of the nonlinear refractive index of both the sample glass substrate and the deposited layer of quantum dots were evaluated using the proposed technique. To characterize the inhomogeneous distribution of the samples’ nonlinear optical properties, we proposed plotting an optical nonlinearity map calculated as a local standard deviation of the diffraction pattern intensities induced by noncollinear degenerate phase modulation.

AutoDisk: Automated diffraction processing and strain mapping in 4D-STEM

Development in lattice strain mapping using four-dimensional scanning transmission electron microscopy (4D-STEM) method now offers improved precision and feasibility. However, automatic and accurate diffraction analysis is still challenging due to noise and the complexity of intensity in diffraction patterns. In this work, we demonstrate an approach, employing the blob detection on cross-correlated diffraction patterns followed by a lattice fitting algorithm, to automate the processing of four-dimensional data, including identifying and locating disks, and extracting local lattice parameters without prior knowledge about the material. The approach is both tested using simulated diffraction patterns and applied on experimental data acquired from a Pd@Pt core-shell nanoparticle. Our method shows robustness against various sample thicknesses and high noise, capability to handle complex patterns, and picometer-scale accuracy in strain measurement, making it a promising tool for high-throughput 4D-STEM data processing.

Inverse Multislice Ptychography by Layer-Wise Optimisation and Sparse Matrix Decomposition

We propose algorithms based on an optimisation method for inverse multislice ptychography in, e.g. electron microscopy. The multislice method is widely used to model the interaction between relativistic electrons and thick specimens. Since only the intensity of diffraction patterns can be recorded, the challenge in applying inverse multislice ptychography is to uniquely reconstruct the electrostatic potential in each slice up to some ambiguities. In this conceptual study, we show that a unique separation of atomic layers for simulated data is possible when considering a low acceleration voltage. We also introduce an adaptation for estimating the illuminating probe. For the sake of practical application, we finally present slice reconstructions using experimental 4D scanning transmission electron microscopy (STEM) data.

Synthesis and Characterization of Methyl Ammonium Lead Halide Perovskite MAPbI3 for Applications in Photodetector Devices

Methyl ammonium lead iodide (CH3NH3PbI3) Perovskite was synthesized by a mixing method in one and two steps. The ethanol solvent was also used to dissolve CH3NH3I that is compared with isopropanol solvent. The characterizations of synthesized perovskite samples include the structural properties, morphological characteristics, and optical properties. The intensity and orientation in X-ray diffraction patterns appear clearly in ethanol solvent. Additionally, the ethanol solvent increases the grain size of perovskite which is homogeneous of the surface morphology. It causes a decrease in the wavelength of absorbance edge in addition to an increase in the energy bandgap value. The photodetector parameters for MAPbI3 perovskites cover the PbS nanocrystal which was prepared on the FTO glass dissolved by Isopropanol and DMF where the responsivity Rλ= 0.0037 and the quantum efficiency QE=1.016% was under λ nm =650 nm and Vbias=0V. These values were decreased by using Ethanol solvent.