Phase Contrast Research Articles

A hybrid simulation method towards the gamma ray phase contrast imaging for metallic material

A high efficiency simulation method for propagation-based phase-contrast imaging, called directional macro-wavefront (DMWF), is developed with the aim of simulating high-energy phase-contrast imaging. This method takes both Monte Carlo and wave optical propagation into consideration. Traditional wave-optics-based simulation methods for phase-contrast imaging encounter unacceptable computational complexity when high-energy radiation is used. In contrast, this method effectively addresses this issue by using macro-wavefront integration. Several simulation examples using typical parameters of inverse Compton scattering sources are presented to illustrate the excellent energy adaptability and efficiency of the DMWF method. This method provides a more efficient approach for phase-contrast imaging simulations, which will drive the advancement of high-energy phase-contrast imaging.

Probing microstructure evolution of Si/C anode for Li-ion batteries via synchrotron transmission X-ray tomographic microscopy

Holding great potentials as an excellent anode for Li-ion batteries, Si has received enormous attention, and its degradation theory has been enriched extensively based on various characterizations over time. To provide a more comprehensive diagnosis for current Si/C anodes, ex situ phase-contrast synchrotron transmission X-ray tomographic microscopy (TXTM) is applied to study a Si/C electrode sampled at representative cycling numbers. Through a series of data segmentations and identifications, three-dimensional Si/C electrodes are described in details with both global and localized structure features, which are rationally linked to the electrochemical characteristics as well as the previous discoveries. This successfully establishes an updated electrode-level failure process for common Si/C anodes where the electrode degradation is primarily initiated by the nonstop Si-phase pulverization with continually-expanded LixSi/electrolyte interface, and manifested as the internal void space expansion and the ever-growing electrode thickness. Bearing this in mind, multiple complementary and synergistic solutions towards limiting the intrinsic Si rupture and electrolyte decomposition should be developed to ensure a high-performance Si-based anode over long-term cycling for Li-ion battery in the near future.

Enhanced image transmission via four-wave mixing with assisted spiral phase contrast in hot atoms

Due to the diffusion motion of gas atoms, the object contour after frequency conversion becomes blurred, and the edge information of the image is always lost. Here, with assisted spiral phase contrast (SPC) imaging, we propose a scheme to preserve object edge information and enhance image recognition via four-wave mixing (FWM) process. The experimental results show that the algorithm can improve the structural similarity (SSIM) of object contour and the whole similarity of image. This work may contribute to the improvement of image quality via frequency conversion in atomic ensembles, and provides a possible implementation in all-optical image processing.

Structural and functional fetal cardiac imaging using low field (0.55 T) MRI.

This study aims to investigate the feasibility of using a commercially available clinical 0.55 T MRI scanner for comprehensive structural and functional fetal cardiac imaging. Balanced steady-state free precession (bSSFP) and phase contrast (PC) sequences were optimized by in utero studies consisting of 14 subjects for bSSFP optimization and 9 subjects for PC optimization. The signal-to-noise ratio (SNR) of the optimized sequences were investigated. Flow measurements were performed in three vessels, umbilical vein (UV), descending aorta (DAo), and superior vena cava (SVC) using the PC sequences and retrospective gating. The optimized bSSFP, PC and half-Fourier single shot turbo spin-echo (HASTE) sequences were acquired in a cohort of 21 late gestation-age fetuses (>36 weeks) to demonstrate the feasibility of a fetal cardiac exam at 0.55 T. The HASTE stacks were reconstructed to create an isotropic reconstruction of the fetal thorax, followed by automatic great vessel segmentations. The intra-abdominal UV blood flow measurements acquired with MRI were compared to ultrasound UV free-loop flow measurements. Using the parameters from 1.5 T as a starting point, the bSSFP sequences were optimized at 0.55 T, resulting in a 1.6-fold SNR increase and improved image contrast compared to starting parameters, as well as good visibility of most cardiac structures as rated by two experienced fetal cardiologists. The PC sequence resulted in increased SNR and reduced scan time, subsequent retrospective gating enabled successful blood flow measurements. The reconstructions and automatic great vessel segmentations showed good quality, with 18/21 segmentations requiring no or minor refinements. Blood flow measurements were within the expected range. A comparison of the UV measurements performed with ultrasound and MRI showed agreement between the two sets of measurements, with better correlation observed at lower flows. We demonstrated the feasibility of low-field (0.55 T) MRI for fetal cardiac imaging. The reduced SNR at low field strength can be effectively compensated for by strategically optimizing sequence parameters. Major fetal cardiac structures and vessels were consistently visualized, and flow measurements were successfully obtained. The late gestation study demonstrated the robustness and reproducibility at low field strength. MRI performed at 0.55 T is a viable option for fetal cardiac examination.

Analysis of laser beam welding with superimposed 445 and 1070 nm wavelength lasers on copper by in situ synchrotron diagnostics

In laser welding, precision and reproducibility are fundamentally dependent on temporal and spatial processes of energy input. Induced by the dynamics of the melt pool, pressure equilibria in the vapor capillary, and solidification behavior, different weld seam qualities are achieved. To obtain the lowest possible defect frequency, new tailored joining strategies need to be investigated using multibeam and multiwavelength approaches. To improve the quality by influencing the process dynamics, a dual-beam approach is investigated that superimposes a stationary laser beam with a wavelength of 445 nm with a spatially modulated laser beam with a wavelength of 1070 nm. The aim is to utilize ∼10 times higher absorption of a 445 nm diode laser on copper with the high focusability of a 1070 nm fiber laser. In this context, the influence of the relative positions of the two beams to each other on the weld seam quality is investigated, while one of the beams moves either in front, behind, or coaxial to the other beam following the path of a line weld. The main objective is to observe how the laser beams influence each other and how the capillary depth and porosity vary for different parameters. To visualize the process dynamics, the welding experiments on copper are performed at the Deutsches Elektronen-Synchrotron DESY by means of in situ phase contrast videography. Quality-determining weld properties like the distribution of pores or process fluctuations are then extracted automatically from the image sequences by means of a trained neuronal network.

Research on adaptive optics technology based on phase contrast Gerchberg Saxton algorithm

Abstract In wireless optical communication, the optical signal passes through the atmospheric turbulence, resulting in the simultaneous distortion of the amplitude and phase of the optical signal at the receiving end. This article applies the idea of phase contrast method to simultaneously compensate the amplitude and phase of the optical signal at the receiving end, derives the mapping relationship between the compensated phase and light intensity, and obtains the required compensated phase for full-field compensation. Numerical calculations show that when the difference between zero-frequency phase compensation and nonzero-frequency phase compensation is ±π, the maximum light intensity compensation is obtained. Based on the Gerchberg Saxton algorithm, a new method is proposed to invert the compensated phase with the maximum light intensity after full-field compensation and perform full-field correction through the adaptive optical system. The numerical calculation and experiment show that the phase contrast Gerchberg Saxton algorithm can effectively compensate the distorted optical signals under different turbulence, and thus the received signals of optical wireless communication can be corrected in full field.

Pyrolysis front detection in carbon phenolic composites using x-ray computed tomography

Carbon phenolic composites are used as thermal protection systems (TPS) materials on space capsules to protect them from the hot aerothermal environment. The phenolic resin in the composite material decomposes (pyrolyzes) at low temperatures resulting in a pyrolysis front within the material. The detection of the pyrolysis front after exposure to heat has historically been achieved by physically sectioning cross-sections of the material. We combine the phase contrast retrieval method to reconstruct x-ray computed tomography scans along with image convolution to identify the pyrolysis front in carbon phenolic composites. Unlike the standard filtered back projection method that captures only the carbon phase, the phase contrast retrieval method uses both the attenuation coefficients and refractive indices to illuminate all three phases (carbon, resin, and voids) of carbon phenolic composites. Image convolution is applied on scans reconstructed using the phase contrast retrieval method to develop a density map of the composite to locate the pyrolysis front. The analysis is performed on a sample of phenolic impregnated carbon ablator that was tested in an arc-jet facility. For the sample analyzed, the depth of the pyrolysis front from the surface of the sample is calculated to be 2.150 ± 0.148 mm. Although the proposed approach is applied to detect the pyrolysis front, the tools can be used to illuminate the structure of any carbon phenolic composite, and we propose the use of the phase contrast retrieval method as a methodological standard to analyze carbon phenolic composites used on space capsules.

Self-healing spiral phase contrast imaging

Spiral phase contrast imaging alleviates the information load by extracting the geometric features of objects and is one of the most representative branches of instant imaging processing. The self-healing capacity of edge detectors can enhance their robustness to obstacles in practical applications. Here, a self-healing spiral phase contrast imaging scheme is proposed and experimentally demonstrated by a liquid crystal edge detector combining a spiral phase, an axicon phase, and a lens phase. The spiral phase is encoded into a liquid crystal by photopatterning. Self-healing contrast imaging is characterized by a series of edge images of both high-contrast amplitude-type and low-contrast phase-type objects. This work extends the self-healing capacity of these detectors to instant imaging processing and paves the way for optical applications with self-healing features.

Averrhoa carambola Leaf Extract Induces Apoptosis-Like Death with Increased ROS Generation in Leishmania donovani.

The parasitic disease leishmaniasis is responsible for high mortality and morbidity rates worldwide. The visceral form is the most severe form of leishmaniasis (or leishmaniosis), which is caused predominantly by Leishmania donovani. Currently, clinically recommended antileishmanial drugs are not convenient because of several medical complications and resistance issues. Phytocompounds are the best candidates in this regard. The present study aimed to evaluate the antileishmanial activity of Averrhoa carambola leaf extract. The antipromastigote activity and cytotoxicity were assessed using the MTT assay. Morphological distortions were determined using phase contrast microscopy and scanning electron microscopy (SEM). Reactive oxygen species (ROS) production, nonprotein thiol depletion and apoptotic death in promastigotes were determined via flow cytometry. UV-visible spectroscopy and energy dispersive X-ray (EDX) spectroscopy was performed for elemental analysis. Fourier-transform infrared spectroscopy (FTIR) and liquid chromatography‒mass spectrometry (LCMS) were used to characterize the phytocomponent(s) present in the extract. The chloroform extract of Averrhoa carambola leaf (ACCEX) (IC50 = 50.76 ± 1.7µg/mL) exhibited the highest activity, followed by the ethyl acetate, hexane, and methanol extracts. ACCEX has also exhibited lower toxicity towards host macrophages. ACCEX also induced morphological distortions in promastigotes, with significant generation of ROS and the concomitant apoptosis initiation followed by a decrease in the nonprotein thiol level. The major phytometabolites present in ACCEX were identified from the National Institute of Standards and Technology (NIST) database and from a literature review. This study suggested that Averrhoa carambola leaf extracts are rich in some classes of biologically active phytocompounds and exhibit good antileishmanial activity.

BSSFP Phase Contrast (PC-SSFP) at 0.55 T Applied to Aortic Flow

BackgroundThere is a growing interest in the development and application of mid-field (0.55T) for cardiac MR, including flow imaging. However, aortic flow imaging at 0.55T has limited SNR, especially in diastolic phases where there is reduced inflow-driven contrast for spoiled gradient echo (GRE) sequences. The low SNR can limit the accuracy of flow and regurgitant fraction measurements. MethodsIn this work, we developed a 2D phase contrast (PC) acquisition with balanced steady state free precession (bSSFP), termed PC-SSFP, for flow imaging and quantification at 0.55T. This PC-SSFP approach precisely nulls the 0th and 1st gradient moments at both the TE and TR, except for the flow-encoded acquisition, for which the 1st gradient moment at the TE is determined by the VENC. Our proposed sequence was tested in both phantoms and in healthy volunteers (n=11), to measure aortic flow. In volunteers, both a breath-hold and a free-breathing protocol, with averaging to increase SNR, were obtained. Total flow, peak flow, cardiac output and SNR were compared for PC-SSFP and PC-GRE. Stroke volumes were also measured and compared to planimetry method. ResultsIn a phantom, SNR was significantly higher using PC-SSFP compared to PC-GRE (25.5±9.6 vs 8.2±2.9), and the velocity measurements agreed well (R = 1.00). In healthy subjects, for both breath-hold (bh) and free-breathing (fb) protocols, PC-SSFP measured accurate peak flow (fb: R = 0.99, bh: R = 0.96) and cardiac output (fb: R = 0.98, bh: R = 0.88), compared to PC-GRE, accurate stroke volume (fb: R = 0.94, bh: R = 0.97), compared to planimetry measurement, and offered constant high SNR (fb: 28±9 vs 18±6, bh: 24±7 vs 11±3) over the cardiac cycle in 11 subjects. ConclusionPC-SSFP is a more reliable evaluation tool for aortic flow quantification, when compared to the conventional PC-GRE method at 0.55T, providing higher SNR, and thus potentially more accurate flows.

Chinese Herbs for Inducing Rat Bone Marrow Mesenchymal Stem Cells Differentiated into Neuron-Like Cells

The purpose of this study was to observe the influence of two Chinese herbs of ligustrazine and Xuefuzhuyu injection on neuron-like cells differentiation from rat bone marrow mesenchymal stem cells (BMSCs) respectively. Most primarily cultured BMSCs adhered to the wall at 3 days after cultured, which proliferated faster after passaged, and the 5th passage of cells were mostly purified into BMSCs. In the present study, the 5th passage of BMSCs were (97.51±1.22) % CD44 positive, but negative for CD45, which were identified by immunocytochemical technique. Serum-free low-sugar Dulbecco’s modified Eagle’s medium (L-DMEM) contains 1.25 g/L ligustrazine and 3.0 g/L Xuefuzhuyu injection were used to induce the 5th passage of BMSCs respectively in vitro. Neuron-like cells with prominence and bifurcation could be detected after induction under an inverted phase contrast microscope. The immunocytochemical method showed that nestin and neuron-specific enolase (NSE) were positive in neuron-like cells, but without glial fibrillary acidic protein (GFAP) expression. Both ligustrazine and Xuefuzhuyu injection have the potential for inducing neuron-like cells differentiation from rat bone marrow mesenchymal stem cells respectively. Compared with Xuefuzhuyu injection-induced cells, neuron-like cells induced with ligustrazine might be better in the level of morphological changes, as well as nestin and NSE expression.

Abstract 24: Effects Of Intensive Blood Pressure Lowering on Brain Tissue Pulsatility in Hypertensive Patients

Recent studies have shown an association between blood pressure (BP), particularly pulse pressure (PP), in increasing brain tissue pulsatility. However, these studies were conducted in a phantom model or in healthy normotensive adults. Effects of intensive BP lowering on brain tissue pulsatility in hypertensive patients remain unknown. Accordingly, we performed a randomized clinical trial to compare effects of intensive BP lowering to target 24-h ambulatory BP <120/70 mmHg (n=26) vs. target of <130/80 mmHg in the control arm (n =19) in hypertensive patients aged 55-79 with normal cognitive function. The brain tissue pulsatility was assessed by the total tissue motion over one cardiac cycle, using CINE phase contrast MRI, with the velocity encoded in all three directions. In each cardiac cycle, the velocity of the tissue was measured at 16 time points. Brain tissue pulsatility was assessed at baseline and after 1 year of follow up. We found that 24-h ambulatory systolic BP (SBP) was reduced from 134.3±9.8 to 112.1±7.2 mmHg in the intensive arm and from 138.5±11.3 to 122.4±7.8 mmHg in the control arm (both p<0.01). The magnitude of 24-h SBP reduction from baseline was greater in the intensive arm than control arm (23.6 vs. 13.1 mmHg, p=0.052) while 24-h diastolic BP was reduced similarly in both groups (11.6 vs. 9.6 mmHg, p=0.8). Similarly, PP based on 24-h BP was reduced from 57.5±11.7 to 45.1±12.1 mmHg in the intensive BP arm and from 62.2±10.6 to 55.4±10.5 mmHg in the control arm (both p<0.01). The magnitude of PP reduction appeared greater in the intensive compared to control arm but was not statistically different (12.4 vs. 6.8 mmHg, p=0.08). We found that the overall gray-white matter tissue pulsatility per cardiac cycle remained unchanged after 12 months in the intensive arm (0.98±0.18 mm to 0.95±0.17 mm) while the brain pulsatility tended to increase in the control arm (0.85±0.17 mm to 0.92±0.16 mm, p=0.09 for treatment group, interaction-p=0.04). Similarly, the white matter (WM) tissue motion remained unchanged in the intensive arm (0.91±0.16 mm to 0.88±0.15 mm) while the WM pulsatility tended to increase in the control arm (from 0.77±0.14 mm to 0.84±0.15 mm, p=0.06 for group, interaction p=0.03). In conclusion, our data suggested a novel effect of intensive BP lowering in preventing the rise in brain tissue pulsatility in hypertensive patients, which may have an implication in the prevention of an accelerated brain injury related to hypertension.

Rapid flowing cells localization enabled by spatiotemporal manipulation of their holographic patterns.

Lab-on-a-Chip microfluidic devices present an innovative and cost-effective platform in the current trend of miniaturization and simplification of imaging flow cytometry; they are excellent candidates for high-throughput single-cell analysis. In such microfluidic platforms, cell tracking becomes a fundamental tool for investigating biophysical processes, from intracellular dynamics to the characterization of cell motility and migration. However, high-throughput and long-term cell tracking puts a high demand on the consumption of computing resources. Here, we propose a novel strategy to achieve rapid 3D cell localizations along the microfluidic channel. This method is based on the spatiotemporal manipulation of recorded holographic interference fringes, and it allows fast and precise localization of cells without performing complete holographic reconstruction. Conventional holographic tracking is typically based on the phase contrast obtained by decoupling the calculation of optical axial and transverse coordinates. Computing time and resource consumption may increase because all the frames need to be calculated in the Fourier domain. In our proposed method, the 2D transverse positions are directly located by morphological calculation based on the hologram. The complex-amplitude wavefronts are directly reconstructed by spatiotemporal phase shifting to calculate the axial position by the refocusing criterion. Only spatial calculation is considered in the proposed method. We demonstrate that the computational time of transverse tracking is only one-tenth of the conventional method, while the total computational time of the proposed method decreases up to 54% with respect to the conventional approach. The proposed approach can open the route for analyzing flow cytometry in quantitative phase microscopy assays.

Experimental review and accuracy of etchants used for phase analysis of SAF2507 Super Duplex Stainless Steel

The mechanical and corrosion properties of duplex stainless steels (DSS) depend on the distribution of ferrite and austenite as well as the presence of secondary phases. It is therefore necessary to accurately determine both the distribution of the phases and their morphology. The aim of this research is to define a standard method for the determination of the volume fraction of the phases present in a SAF2507 SDSS by analysing images acquired by light microscope. To do this, the material is heat-treated at 850 °C for 5 min, 15 min, 30 min, 1h, 5h to stimulate the formation of the σ-phase. The metallographic etchant capable of maximising phase contrast is then identified. Micrographic analyses are performed using different reagents at different holding times and temperatures, in order to find the best combination. A standard procedure is then defined for the image analysis. The data obtained were are processed to calculate the phase distribution. The results are compared with the quantitative analysis performed using X-ray diffraction as reference.The research evidence that Kalling's reagent is best etchant for fully solubilised materials, as it accurately estimates ferrite and austenite content. On the other hand, Marble's reagent should be preferred for the detection of σ-phase. For comprehensive analysis of all phases, Murakami's reagent is recommended.The approach defined in this paper not only improves the understanding of the microstructure of DSS, but also provides an important tool for industrial quality control and material characterisation.

Exploring Label-Free Imaging Techniques with Copper Sulfide Microspheres for Observing Breast Cancer Cells.

A single breast cancer is a prevalent form of cancer, affecting over 2.3 million women worldwide, as reported by the World Health Organization. Recently, researchers have extensively explored the utilization of biomaterials in breast cancer theranostics. One notable biomaterial being investigated is various structures of copper sulfide (CuS). In this work, a microsphere (MS) structure composed of CuS was employed for label-free imaging of MCF-7 breast cancer cells and normal Vero cells, respectively. Various label-free imaging techniques, such as bright field, dark field, phase contrast (PC), and differential interference contrast (DIC), were employed to capture images of CuS MSs, cell, and intact CuS MSs within a cell. The study compared the outcomes of each imaging technique and determined that DIC imaging provided the highest resolution for cells incubated with CuS MSs. Furthermore, the combination of PC and DIC techniques proved to be effective for imaging breast cancer cells in conjunction with CuS MSs. This research underscores the potential of CuS MSs for label-free cell detection and emphasizes the significance of selecting appropriate imaging techniques to attain high-quality images in the field of cell observation.

NeuroQuantify – An image analysis software for detection and quantification of neuron cells and neurite lengths using deep learning

BackgroundThe segmentation of cells and neurites in microscopy images of neuronal networks provides valuable quantitative information about neuron growth and neuronal differentiation, including the number of cells, neurites, neurite length and neurite orientation. This information is essential for assessing the development of neuronal networks in response to extracellular stimuli, which is useful for studying neuronal structures, for example, the study of neurodegenerative diseases and pharmaceuticals. New methodWe have developed NeuroQuantify, an open-source software that uses deep learning to efficiently and quickly segment cells and neurites in phase contrast microscopy images. ResultsNeuroQuantify offers several key features: (i) automatic detection of cells and neurites; (ii) post-processing of the images for the quantitative neurite length measurement based on segmentation of phase contrast microscopy images, and (iii) identification of neurite orientations. Comparison with existing methodsNeuroQuantify overcomes some of the limitations of existing methods in the automatic and accurate analysis of neuronal structures. It has been developed for phase contrast images rather than fluorescence images. In addition to typical functionality of cell counting, NeuroQuantify also detects and counts neurites, measures the neurite lengths, and produces the neurite orientation distribution. ConclusionsWe offer a valuable tool to assess network development rapidly and effectively. The user-friendly NeuroQuantify software can be installed and freely downloaded from GitHub at https://github.com/StanleyZ0528/neural-image-segmentation.

Self-Indicating Polymer Prodrug Nanoparticles for pH-Responsive Drug Delivery in Cancer Cells and Real-Time Monitoring of Drug Release.

Amphiphilic self-indicating and responsive polymer-based prodrugs have generated much interest as potential stimuli-responsive intelligent drug delivery systems (DDS) due to their ability to selectively deliver drugs to the cancer cells and to monitor real-time cellular uptake of the drug by imaging technique(s). In this direction, we have synthesized a new pH-responsive N-vinyl-2-pyrrolidone and coumarin-based fluorescent self-indicating polymeric prodrug (SIPD), poly(NVP)-b-poly(FPA.DOX-r-FPA-r-CA). This block copolymer prodrug self-assembled into stable micellar nanoparticles under physiological conditions that reduced undesirable drug leakage to normal cells but resulted in the release of the anticancer drug doxorubicin (DOX) in cancer cells because of acidic pH-induced cleavage of imine bonds between DOX and the copolymer. While the polymer was found to be highly biocompatible with both normal (HEK-293) cells and cancer (MCF-7) cells even at high concentrations by MTT assay, the polymer prodrug nanoparticles showed toxicity even higher than that of free DOX in cancer cells. Phase contrast microscopy also depicted the cytotoxic effects of the nanoparticles on cancer cells. The coumarin units present in the polymer served as a fluorescence resonance energy transfer (FRET) pair with the covalently attached DOX molecules, which was established by steady-state and time-resolved fluorescence spectroscopy. Furthermore, confocal microscopy results confirmed the FRET phenomenon, as the fluorescence intensity of coumarin in the micellar nanoparticles remained quenched initially in MCF-7 cells but recovered with time as the DOX molecules were released and gradually shifted toward the targeted nucleus. All of these studies implied that the synthesized prodrug nanoparticles may provide another viable option for delivering chemotherapeutic drugs into cancer cells with a capability of real-time monitoring of drug release.

Differential phase contrast from electrons that cause inner shell ionization

Differential Phase Contrast (DPC) imaging, in which deviations in the bright field beam are in proportion to the electric field, has been extensively studied in the context of pure elastic scattering. Here we discuss differential phase contrast formed from core-loss scattered electrons, i.e. those that have caused inner shell ionization of atoms in the specimen, using a transition potential approach for which we study the number of final states needed for a converged calculation. In the phase object approximation, we show formally that differential phase contrast formed from core-loss scattered electrons is mainly a result of preservation of elastic contrast. Through simulation we demonstrate that whether the inelastic DPC images show element selective contrast depends on the spatial range of the ionization interaction, and specifically that when the energy loss is low the delocalisation can lead to contributions to the contrast from atoms other than that ionized. We further show that inelastic DPC images remain robustly interpretable to larger thicknesses than is the case for elastic DPC images, owing to the incoherence of the inelastic wavefields, though subtleties due to channelling remain. Lastly, we show that while a very high dose will be needed for sufficient counting statistics to discern differential phase contrast from core-loss scattered electrons, there is some enhancement of the signal-to-noise ratio with thickness that makes inelastic DPC imaging more achievable for thicker samples.

Differential phase contrast STEM image calculation software – Magnifier

An innovative software with a user-friendly interface for calculation of differential phase contrast (DPC) scanning transmission electron microscopy images (integrated iDPC- and differentiated dDPC-STEM) is presented. The underlying algorithm is described and the program functionalities are demonstrated on the examples of Li5OsO6, α-Ga2O3, and LiCoO2. The software supports interpretation of DPC-STEM images, which is crucial for qualitative and quantitative analysis of crystal structures and defects.

Exploration of the thickness-depended dynamic properties of differential phase contrast (DPC) and integrated differential phase contrast (iDPC)

A study on DPC and iDPC images of crystals is achieved with simulation. It highlights the use of electron wave intensity distribution to visualize the dynamic effect on DPC and iDPC contrasts. Electron waves near heavy atoms exhibit significant oscillations and rapid intensity decay. This oscillation causes DPC and iDPC signal inversion. Bloch wave theory is used to derive DPC and iDPC intensity distributions, elucidating the impact of dynamic effect on the contrast.