Field Microscopy Research Articles

Stacking Fault Segregation Imaging With Analytical Field Ion Microscopy.

Stacking faults (SFs) are important structural defects that play an essential role in the deformation of engineering alloys. However, direct observation of SFs at the atomic scale can be challenging. Here, we use the analytical field ion microscopy, including density functional theory-informed contrast estimation, to image local elemental segregation at SFs in a creep-deformed solid-solution single-crystal alloy of Ni-2 at% W. The segregated atoms are imaged brightly, and time-of-flight spectrometry allows for their identification as W. We also provide the first quantitative analysis of trajectory aberration, with a deviation of approximately 0.4 nm, explaining why atom probe tomography could not resolve these segregations. Atomistic simulations of substitutional W atoms at an edge dislocation in face-centered cubic Ni using an analytic bond-order potential indicate that the experimentally observed segregation is due to the energetic preference of W for the center of the SF, contrasting with, for example, Re segregating to partial dislocations. Solute segregation to SF can hinder dislocation motion, increasing the strength of Ni-based superalloys. Yet, direct substitution of Re by W, envisaged to lower the superalloys' costs, requires extra consideration in alloy design since these two solutes do not have comparable interactions with structural defects during deformation.

Eco-Conscious Approach to Synthesizing Aluminum Oxides Using Nonthermal Plasma Technology

AlO is a prevalent oxide compound composed of aluminum and oxygen, with the chemical formula Al2O3. This study aims to prepare aluminum oxide nanoparticles using aluminum nitrate nonahydrate Al(NO[Formula: see text] 9H2O through direct exposure to a plasma jet system using argon gas, as plasma is the fourth state of matter and a common effective method. The major study in the preparation of Al2O3 nanoparticles, which is a physical method, examines the effect of aluminum oxide nanoparticles against bacteria and fungi. Different methods were used for diagnosis. The X-ray diffraction examination showed an average particle size of 37.8 nm. It was also found through the UV-Vis examination that a surface plasmon resonance was formed at 300 nm with an energy gap value of 4.21 eV. The electron microscope field emission scanning (FE-SEM) was used to study the surface morphology. The results of biological testing showed that aluminum oxide nanoparticles have high antibacterial and antifungal activity.

Combining array-assisted SERS microfluidic chips and machine learning algorithms for clinical leukemia phenotyping

The disease progression and treatment options of leukemia between different subtypes vary considerably, emphasizing the importance of phenotyping. However, early typing of leukemia remains challenging due to the lack of highly sensitive and specific analytical tools. Herein, we propose a SERS-based platform for the classification of acute lymphoblastic T-cell leukemia (T-ALL) and chronic myeloid leukemia (CML) through the combination of machine learning and microfluidic chips. The ordered arrays in microfluidic channels reshape the microscopic flow field and contacting interfaces, facilitating the uniform and efficient capture of tumor cells. To enable phenotypic analysis, spectrally orthogonal SERS aptamer nanoprobes were applied, providing composite spectral signatures of individual cells in accordance with surface protein expression. Further, machine learning algorithms were employed to analyze the SERS signatures automatically, resulting in an accuracy of 98.6 % for 73 clinical blood samples. The results demonstrate that this platform holds promising potential for clinical leukemia diagnosis and precision medicine.

Vortex light field microscopy: 3D spectral single-molecule imaging with a twist

3D single-molecule imaging reveals nanoscale structures in cell volumes but is limited by the need for spectrally distinct fluorophores. We address this limitation with vortex light field microscopy (VLFM), a 3D spectral single-molecule localization technique with 25 nm spatial and 3 nm spectral precision over a 4 µm depth of field. By modifying our previous single-molecule light field microscope with an azimuthally oriented prism array, we generated spectral disparity orthogonal to axial disparity, enabling simultaneous spatial and spectral localization on a single detector. We demonstrate VLFM with four-color 3D single-particle tracking and two-color 3D dSTORM imaging in fixed cells, successfully identifying dyes with spectral peaks just 15 nm apart. This shows VLFM’s potential for enhancing spatial biology workflows requiring highly multiplexed imaging.

In Situ Diagnosis and Digital Cataloguing of Plant Pathogenic Fungi Through Mobile‐Based Foldscope Microscopy

ABSTRACTAgriculture confronts multifaceted challenges across the spectrum of crop production, with pest and disease management being a prominent concern. Timely diagnosis of crop diseases is imperative for mitigating production costs and curbing the adverse environmental impacts of chemical pesticides. In the present investigation, mobile phone‐based foldscope microscopy (MBFM) was used to diagnose various field samples infected with fungal diseases of field and horticultural crops, and the same was validated with the normal microscope pictures and field symptoms. The MBFM was also used to diagnose seed‐borne microflora associated with wheat and spores of commercial formulation of bioagents and validated. The MBFM utilises both symptoms and morphological structures of pathogen for in situ field diagnosis and hence advantages over the symptom‐based mobile Apps. This study underscores the utility of foldscope microscope as a potent technique for plant pathologists and extension workers to enable real‐time and in situ identification of diseases caused by fungal pathogens in various agricultural crops.

Statistical method accounts for microscopic electric field distortions around neurons when simulating activation thresholds.

Notwithstanding advances in computational models of neuromodulation, there are mismatches between simulated and experimental activation thresholds. Transcranial Magnetic Stimulation (TMS) of the primary motor cortex generates motor evoked potentials (MEPs). At the threshold of MEP generation, whole-head models predict macroscopic (at millimeter scale) electric fields (50-70 V/m) which are considerably below conventionally simulated cortical neuron thresholds (200-300 V/m). We hypothesize that this apparent contradiction is in part a consequence of electrical field warping by brain microstructure. Classical neuronal models ignore the physical presence of neighboring neurons and microstructure and assume that the macroscopic field directly acts on the neurons. In previous work, we performed advanced numerical calculations considering realistic microscopic compartments (e.g., cells, blood vessels), resulting in locally inhomogeneous (micrometer scale) electric field and altered neuronal activation thresholds. Here we combine detailed neural threshold simulations under homogeneous field assumptions with microscopic field calculations, leveraging a novel statistical approach. We show that, provided brain-region specific microstructure metrics, a single statistically derived scaling factor between microscopic and macroscopic electric fields can be applied in predicting neuronal thresholds. For the cortical sample considered, the statistical methods match TMS experimental thresholds. Our approach can be broadly applied to neuromodulation models, where fully coupled microstructure scale simulations may not be practical.

Was bone used in the glaze of the ancient Qiong kilns for the production of tang dynasty opaque glaze celadon?

Being an important source of primary celadon in ancient China, the Qiong kiln is one of the few kilns that can skillfully produce opaque glaze celadon, which is of great significance in the history of Chinese ceramics. In this study, the chemical composition, microstructure, and crystalline phase of sixteen pieces of opaque glaze celadon excavated from the site of Qiong kiln Shifangtang dated at the Tang Dynasty were investigated by using ultra depth of field microscopy, scanning electron microscopy, energy spectrometry, and micro confocal Raman spectrometry. The findings indicate that Fe is the predominant coloring element in the ceramic glaze, and Cu is sometimes a secondary coloring element. During porcelain firing, washed plant ash was used to increase the phosphorus content of the glaze, while some wares incorporated animal ashes as a flux to improve glaze emulsification.

Kilohertz volumetric imaging of in-vivo dynamics using squeezed light field microscopy.

Volumetric functional imaging of transient cellular signaling and motion dynamics poses a significant challenge to current microscopy techniques, primarily due to limitations in hardware bandwidth and the restricted photon budget within short exposure times. In response to this challenge, we present squeezed light field microscopy (SLIM), a computational imaging method that enables rapid detection of high-resolution three-dimensional (3D) light signals using only a single, low-format camera sensor area. SLIM pushes the boundaries of 3D optical microscopy, achieving over one thousand volumes per second across a large field of view of 550 μm in diameter and 300 μm in depth with a spatial resolution of 3.6 μm laterally and 6 μm axially. Using SLIM, we demonstrated blood cell velocimetry across the embryonic zebrafish brain and in a free-moving tail exhibiting high-frequency swinging motion. The millisecond temporal resolution also enables accurate voltage imaging of neural membrane potentials in the leech ganglion, and in the hippocampus of behaving mice. These results collectively establish SLIM as a versatile and robust imaging tool for high-speed microscopy applications.

Comparative Study of Gleason 7 (3+4) and (4+3) Prostatic Adenocarcinomas with Prog-nostic Criteria and Immunohistochemical Profiles of AMACR, PSA and Ki-67.

To compare Gleason 7 (3+4) and (4+3) prostatic adenocarcinoma (PC) with different prognostic criteria through immunohistochemical analysis with anti-PSA, anti-Ki 67 and anti-AMARC antibodies. We analyzed 221 surgical specimens from patients between 40 and 86 years-old (mean=63) with PC. The immunohistochemical study was performed with anti-PSA, anti-Ki 67 and anti-AMARC. The microscopic fields were photographed with an Olympus DP70 digital camera coupled to an Olympus BX51 microscope and archived in TIFF. Proportion and intensity criteria were used to quantify the anti-PSA antibody and for the anti-Ki 67 antibody, the quantification by similarity of this antibody in breast carcinomas. Anti-AMACR protein expression was based on four scores: negative, weak, moderate and strong. The statistical analysis was performed with the Graph Pad Prism 5 program. In the Gleason score 7 (3+4) we had 91.72% in pT2 and 8.27% in the pT3 group; 8.27% recurrences, of which 90.90% in the pT2 group. In the Gleason score 7 (4+3) we had 77.27% in the pT2 group and 22.72% in the pT3 group and 10.22% of relapses, of which 66.66% in the pT2 group and 33.33% in the pT3 group. In 6.81% of cases there was an increase in the anti-Ki 67 index and in 2.27% of the cases, there was an increase in the immunoexpression of anti-p53 when comparing Gleason score 7 (3+4) with Gleason score 7 (4+3). Our study confirmed differences in the Gleason score 7 (3+4) and Gleason score 7 (4+3) of PC when comparing prognostic criteria. Anti-Ki 67 and anti-PSA antibody immunostaining showed a positive correlation as the Gleason score 7 increased from (3+4) to (4+3).

Field Ion Microscopy of Tungsten Nano-Tips Coated with Thin Layer of Epoxy Resin

This paper presents an analysis of the field ion emission mechanism of tungsten–epoxy nanocomposite emitters and compares their performance with that of tungsten nano-field emitters. The emission mechanism is described using the theory of induced conductive channels. Tungsten emitters with a radius of 70 nm were fabricated using electrochemical polishing and coated with a 20 nm epoxy resin layer. Characterization of the emitters, both before and after coating, was performed using electron microscopy and energy-dispersive X-ray spectroscopy (EDS). The Tungsten nanocomposite emitter was tested using a field ion microscope (FIM) in the voltage range of 0–15 kV. The FIM analyses revealed differences in the emission ion density distributions between the uncoated and coated emitters. The uncoated tungsten tips exhibited the expected crystalline surface atomic distribution in the FIM images, whereas the coated emitters displayed randomly distributed emission spots, indicating the formation of induced conductive channels within the resin layer. The atom probe results are consistent with the FIM findings, suggesting that the formation of conductive channels is more likely to occur in areas where the resin surface is irregular and exhibits protrusions. These findings highlight the distinct emission mechanisms of both emitter types.

Mapping voltage activity in a live mouse brain in 3D using confocal light field microscopy.

Mapping voltage activity in a live mouse brain in 3D using confocal light field microscopy.

A cluster-based incremental potential approach for reduced order homogenization of bones.

We develop a cluster-based model order reduction (called C-pRBMOR) approach for efficient homogenization of bones, compatible with a large variety of generalized standard material (GSM) models. To this end, the pRBMOR approach based on a mixed incremental potential formulation is extended to a clustered version for a significantly improved computational efficiency. The microscopic modeling of bones falls into a mixed incremental class of the GSM framework, originating from two potentials. An offline phase of the C-pRBMOR approach includes both a clustering analysis spatially decomposing the micro-domain within an RVE and a space-time decomposition of the microscopic plastic strain fields. A comparative study on two different clustering approaches and two algorithms for mode identification is additionally conducted. For an online analysis, a cluster-enhanced version of evolution equations for the reduced variables is derived from an effective incremental variational formulation, rendering a very small set of nonlinear equations to be numerically solved. Several numerical examples show the effectiveness of the C-pRBMOR approach. A striking acceleration rate beyond 104 against conventional FE computations and that beyond 103 against the original pRBMOR approach are observed.

Truncated M13 phage for smart detection of E. coli under dark field

BackgroundThe urgent need for affordable and rapid detection methodologies for foodborne pathogens, particularly Escherichia coli (E. coli), highlights the importance of developing efficient and widely accessible diagnostic systems. Dark field microscopy, although effective, requires specific isolation of the target bacteria which can be hindered by the high cost of producing specialized antibodies. Alternatively, M13 bacteriophage, which naturally targets E. coli, offers a cost-efficient option with well-established techniques for its display and modification. Nevertheless, its filamentous structure with a large length-diameter ratio contributes to nonspecific binding and low separation efficiency, posing significant challenges. Consequently, refining M13 phage methodologies and their integration with advanced microscopy techniques stands as a critical pathway to improve detection specificity and efficiency in food safety diagnostics.MethodsWe employed a dual-plasmid strategy to generate a truncated M13 phage (tM13). This engineered tM13 incorporates two key genetic modifications: a partial mutation at the N-terminus of pIII and biotinylation at the hydrophobic end of pVIII. These alterations enable efficient attachment of tM13 to diverse E. coli strains, facilitating rapid magnetic separation. For detection, we additionally implemented a convolutional neural network (CNN)-based algorithm for precise identification and quantification of bacterial cells using dark field microscopy.ResultsThe results obtained from spike-in and clinical sample analyses demonstrated the accuracy, high sensitivity (with a detection limit of 10 CFU/μL), and time-saving nature (30 min) of our tM13-based immunomagnetic enrichment approach combined with AI-enabled analytics, thereby supporting its potential to facilitate the identification of diverse E. coli strains in complex samples.ConclusionThe study established a rapid and accurate detection strategy for E. coli utilizing truncated M13 phages as capture probes, along with a dark field microscopy detection platform that integrates an image processing model and convolutional neural network.Graphical

A-140 Reducing cell count bias with the GloCyte® Automated Cell Counter for CSF: an observational study at Loyola University Medical Center

Abstract Background Accurate STAT cerebrospinal fluid (CSF) cell counts are critical in supporting diagnoses of meningitis, malignancy, demyelinating disease, and hemorrhage. Limitations of automated analyzers to achieve acceptable linearity for the clinically relevant range has maintained manual CSF cell counting as the preferred method. Manual cell counting, performed with a hemocytometer and bright field microscope, is time-consuming, requires specialized skills and depends on human interpretation. This subjectivity inherently introduces the potential for non-random error in the enumeration of both total nucleated cells (TNC) and red blood cells in CSF by manual methods. The purpose of this study was to evaluate and compare the level of bias inherent in manual determination (TNC) in CSF as compared to the GloCyte Automated Cell Counter. Methods Result bias data for CSF specimens processed in the hematology lab at Loyola University Medical Center, a quaternary care 547-bed academic medical center in Maywood, IL, was analyzed for manual cell counting using a Neubauer-improved hemocytometer and GloCyte, an FDA-cleared cell counting device employing fluorescence technology to automate RBC and TNC counts in under 5 minutes, with linearity down to 0 cells/µL. Result bias was determined by defining the “expected result” for both GloCyte and hemocytometer as the initial cell count determined at a 1:5 dilution of a freshly-collected CSF sample and calculating the expected cell count for subsequent serial dilutions of 1:10, 1:20, 1:50, 1:100 for each method. The actual TNC count and the disparity of the actual result from the expected result was recorded as bias. Results Data are summarized below in the Table, and indicate a lower bias for GloCyte compared to manual counts across the range of dilutions. Conclusions This study demonstrates that GloCyte can be implemented as a means of effectively mitigating the reporting bias of CSF TNC counts performed with a Neubauer-improved hemocytometer.

Polyvinyl alcohol assisted citrate based reduction of gold(III) ions: Theoretical design and experimental study on green synthesis of spherical and biocompatible gold nanoparticles

In this study, we demonstrate the synthesis of small gold nanoparticles (typically 8-10 nm) through a green synthesis approach. This method involves utilizing chloroauric acid as the gold precursor, trisodium citrate as a mild reducing and co-capping agent, and polyvinyl alcohol (PVA), as a co-capping and shape-directing agent. This novel synthesis method stands alone as a protocol that involves just mixing the reagents at room temperature and allowing the reaction to proceed at ambient temperature without any disturbance. In the absence of PVA, spherical particles are not formed and the reaction mixture slowly turns black followed by precipitation.The synthesis process was meticulously tracked using time-resolved monitoring of the growth of the localized surface plasmon resonance (LSPR) by UV-vis spectroscopy and transmission electron microscopy. The as-prepared colloidal gold solution was bright red, attributed to the small size (≤ 10 nm) and spherical geometry of nanoparticles. This colloidal solution could be stored indefinitely at room temperature without precipitation or a change in its absorption profile. The nanoparticles remained stable in adverse conditions such as 100 mM NaCl solution, 1×PBS and cell culture medium. Additionally, they could be easily loaded with drugs like doxorubicin by adsorption. The particles were thoroughly characterized using a range of techniques, including UV-vis spectroscopy, attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), high-resolution transmission electron microscopy (HRTEM), hyperspectral-enhanced dark field microscopy (HEDFM), dynamic light scattering (DLS), and X-ray photoelectron spectroscopy (XPS). Cell viability tests conducted on 2D cell lines and 3D spheroids revealed negligible toxicity even at high concentrations. Furthermore, we demonstrate that an advanced version of conventional diffusion-limited aggregation (DLA) schemes, which allows individual clusters to move freely within a domain to form larger aggregates, can effectively replicate the intricate interactions between chloroauric acid, trisodium citrate, and PVA, the agents involved in the synthesis of gold nanoparticles.

Analytic structure of diffusive correlation functions

Diffusion is a dissipative transport phenomenon ubiquitously present in nature. Its details can now be analyzed with modern effective field theory (EFT) techniques that use the closed-time-path (or Schwinger-Keldysh) formalism. We discuss the structure of the diffusive effective action appropriate for the analysis of stochastic or thermal loop effects, responsible for the so-called long-time tails, to all orders. We also elucidate and prove a number of properties of the EFT and use the theory to establish the analytic structure of the n-loop contributions to diffusive retarded two-point functions. Our analysis confirms a previously proposed result by Delacrétaz that used microscopic conformal field theory arguments. Then, we analyze a number of implications of these loop corrections to the dispersion relations of the diffusive mode and new, gapped modes that appear when the EFT is treated as exact. Finally, we discuss certain features of an all-loop model of diffusion that only retains a special subset of n-loop “banana” diagrams. Published by the American Physical Society 2024

Morpho-Anatomical Variations in Sisymbrium irio L. Plants Raised from Seeds Treated with γ Radiation.

This study determines the effect of γ irradiation on seed germination, growth, and morpho-anatomical traits of the Sisymbrium irio L. (London rocket) plant. Seeds irradiated with 2.5, 5, 10, 15, and 20 kGy of γ radiation showed a reduced germination percentage (13.68-56.84%) with reference to the control, showing an inverse relationship with radiation dose. Observations recorded at preflowering, flowering, and postflowering stages of plant growth showed a significant (P < 0.05%) dose-dependent decline in many growth parameters, such as root length, shoot length, shoot dry weight, number of leaves, and pods per plant, due to the radiation effect. However, root dry weight, leaf length, leaf dry weight, number of branches, and number of flowers per plant increased at the lowest dose (2.5 kGy) and then declined steadily with the increasing level of radiation. Likewise, several anatomical features (length of fibers and vessel elements, diameter of vessel elements, proportion of cortex, and vasculature in the stem) showed a consistent decrease with increasing γ irradiation in treated plants compared with the control. However, the pith area and the number of vessels per microscopic field decreased significantly with the lowest radiation dose (2.5 kGy) and then increased gradually with higher doses at each ontogenetic stage. The vulnerability factor in the control as well as treated plants increased with increasing plant age. In treated plants, vulnerability was higher under the effect of low-level radiation than in the control, but it showed an inverse relationship with the increasing level of radiation, thus being the lowest at 20 kGy radiation dose. Mesomorphy also showed an almost similar variation pattern with reference to the radiation dose.

Frost Resistance and Microscopic Properties of Recycled Coarse Aggregate Concrete Containing Chemical Admixtures.

In order to increase the suitability of coarse recycled concrete aggregates and improve the frost resistance of recycled coarse aggregate concrete, this study aims to investigate the effects of an antifreeze-type water-reducing admixture, air-entraining admixture, and antifreeze admixture on the frost resistance of recycled coarse aggregate concrete. The effectiveness of these admixtures is gauged by the mass loss rate and the relative dynamic modulus of elasticity (RDM). Mercury-impressed porosimetry (MIP), super depth of field microscopy, and scanning electron microscopy (SEM) were employed to characterize the hydration products, microstructure, and pore structure of recycled coarse aggregate concrete, with a view to establishing a connection between the microstructural characteristics and the macro properties and analyzing the micro-mechanism of the improvement effect of frost resistance. The test results demonstrate that the admixtures have a significant impact on the frost resistance of recycled coarse aggregate concrete. In particular, the recycled coarse aggregate concrete with an antifreeze admixture (dosage of 1%) and a water-cement ratio of 0.41 exhibited a mass loss of only 1.23% after 200 freezing and thawing cycles, a relative dynamic modulus of elasticity of up to 93.97%; however, the control group had reached the stopping condition at 150 freeze-thaw cycles with more than 10% mass loss. The recycled coarse aggregate concrete with added antifreeze admixture had a tight connection between the aggregate and the paste and a more pronounced improvement in the pore structure, indicating excellent resistance to frost damage.

Microvascular effects of a mixed meal tolerance test: a model validation study

AbstractPurposeEndothelial dysfunction is a pathophysiological change preceding many cardiovascular events. Measuring improvements of endothelial function is challenging when function is already optimal, which may be remediated using a physiological challenge. This study aimed to determine whether imaging assessments can detect microvascular effects of a mixed meal tolerance test (MMTT).MethodsTwenty healthy volunteers (age ≥45 and ≤70 years) underwent two MMTTs at the beginning (Day 1) and end (Day 84) of a twelve‐week period. Imaging methods included laser speckle contrast imaging (LSCI) combined with post‐occlusive reactive hyperaemia (PORH) and local thermal hyperaemia (LTH) challenges, passive leg movement ultrasonography (PLM), and sidestream dark field microscopy (SDFM). Measurements were conducted pre‐MMTT and at 5 timepoints post‐MMTT for PLM and SDFM and 3 timepoints post‐MMTT for PORH and LTH.ResultsNo consistent effects of the MMTT were detected on LSCI LTH, PLM and SDFM endpoints. LSCI PORH maximum perfusion was significantly suppressed 46, 136, and 300 min post‐MMTT administration on Day 1, while residual perfusion decreased significantly 46 and 136 min post‐MMTT on Day 1. However, when repeated on Day 84, PORH endpoints were not significantly affected by the MMTT.ConclusionSDFM, PLM and LSCI LTH endpoints displayed high intra‐subject variability and did not detect consistent effects of MMTT. LSCI PORH endpoints displayed the lowest intra‐subject variability of all assessed endpoints and were affected by the MMTT on Day 1, but not on Day 84. Further standardization of methods or more robust challenges to affect vascular endpoints may be needed.

Scanning Tunneling Microscope‐Characterization of Chemical Vapor Deposition‐Graphene: Ripples and Twisted Bi‐layers at Multiple Scales

Despite numerous limitations, graphene characterization using scanning tunneling microscopy is an important aspect of graphene research. In the present study, an ambient, large effective field of view scanning tunneling microscope (A‐LEF‐STM) is used as a more practical extension of a standard STM for analyzing chemical vapor deposited (CVD)‐graphene: A rigid sample stage, which allows the tip to be relocated to any point over an area of 3.5 × 3.5 mm, is attached to the latter. This simple enhancement allows rough patches spanning hundreds of nanometers on any sample to be easily circumnavigated, almost always without damaging the tip. Ripples and multi‐layer regions including those with twisted bi‐layers, in a graphene sheet grown on a copper foil using CVD, are located using the augmented manoeuvrability, and imaged in high‐definition from micron to angström scales. Insights relating to the resolution with which surfaces of varying roughness can be imaged are developed using simulations and a careful analysis of the scanning process. The enhanced field of view is also utilized to verify the extent of graphene coverage over the entire sample area. The acquired images of single and multi‐layer depositions are carefully interpreted. The applicability of this end‐to‐end characterization process for other samples is also discussed. Overall, this study demonstrates the potential benefits of the A‐LEF‐STM as an eminent characterization tool, complementary to a Raman spectrometer, for CVD‐graphene and other two‐dimensional materials.