High-resolution Electron Microscopy Images Research Articles

Deep Bayesian local crystallography

The advent of high-resolution electron and scanning probe microscopy imaging has opened the floodgates for acquiring atomically resolved images of bulk materials, 2D materials, and surfaces. This plethora of data contains an immense volume of information on materials structures, structural distortions, and physical functionalities. Harnessing this knowledge regarding local physical phenomena necessitates the development of the mathematical frameworks for extraction of relevant information. However, the analysis of atomically resolved images is often based on the adaptation of concepts from macroscopic physics, notably translational and point group symmetries and symmetry lowering phenomena. Here, we explore the bottom-up definition of structural units and symmetry in atomically resolved data using a Bayesian framework. We demonstrate the need for a Bayesian definition of symmetry using a simple toy model and demonstrate how this definition can be extended to the experimental data using deep learning networks in a Bayesian setting, namely rotationally invariant variational autoencoders.

Synthesis and characterisation of Li-modified g-C3N4

Graphitic carbon nitride (g-C3N4) is of great interest in photolysis. However, g-C3N4 suffers from a fast recombination rate of photogenerated electron and hole (e−/h+) pairs. It is hypothesised that surface modification of g-C3N4 with alkali metals is able to suppress the recombination rate of photogenerated e−/h+ pairs. Hence, in the present research, a series of lithium modified g-C3N4 (xLi/g-C3N4 (x = 2.7, 5.0 and 9.0 wt%)) nanocomposites were synthesised by impregnating g-C3N4 with LiOH. The synthesised nanocomposites were characterised using x-ray powder diffraction (XRD), inductive coupled plasma mass spectroscopy (ICP-MS), scanning electron microscopy (SEM), uv–vis diffuse reflectance spectroscopy (DRS UV–Vis), high resolution electron microscopy (HRTEM), photoluminescence (PL), Fourier transform infrared (FT-IR) and thermogravimetric (TGA) analyses. The TGA analysis showed that the thermal stability of the Li/g-C3N4 decreased compared to g-C3N4 due to the enlarged interlayer distance over g-C3N4. The XRD analysis indicates that a larger distance of the in-planar structure motif of g-C3N4 downshifted the (002) diffraction line of the g-C3N4 from 27.60° to 26.83° and weakened its intensity after doping. Increasing the Li+ concentration transformed the Li/g-C3N4 into a disordered graphite nanocomposite. The IR peak intensity at 2174 cm−1 associated with the defect terminal –C≡N increased when the Li+ concentration was increased, indicating that the incorporation of Li+ reduced the degree of melamine condensation and formed g-C3N4 with more defect sites. The HRTEM images showed that the g-C3N4 thin nanosheet structure became uneven and wrinkled after doping. Rock-like particles were observed when the Li+ concentration exceeds 5 wt% Li/g-C3N4. Similar rock-like and plate-like particles with voids were observable in the nanocomposites’ SEM images. The UV–Vis analysis indicates that Li+ doping reduced visible light sensitivity of the Li/g-C3N4 nanocomposites compared to g-C3N4, possibly due to the distortion of the g-C3N4 planar structure. The PL analysis indicates that the photogenerated recombination rate e−/h+ pairs were suppressed even though the sensitivity towards visible light decreased.

Hybrid nanostructures of Ag/Au-ZnO synthesized by pulsed laser ablation/irradiation in liquid

In this study, properties of zinc oxide (ZnO) are tuned by forming hybrid nanomaterials via pulsed laser ablation and irradiation in liquid. Ag/Au bimetallic nanocolloids synthesized by pulsed laser ablation in water are mixed with ZnO powder followed by laser irradiation to form Ag/Au-ZnO nanohybrids. The optical absorption spectra of the hybrid nanomaterials show the presence of plasmonic peaks of Ag/Au. The morphological studies of the nanohybrids reveal the changes in mixed non-uniform morphology to spherical ones. From the structural analysis, the stability of crystalline structure of ZnO is evidenced in all samples, and the high-resolution transmission electron microscopic images showed atomic fringes that correspond to ZnO and Ag/Au. Elemental analysis revealed the compositions from Zn, O, Ag, and Au and their chemical states are confirmed by X-ray photoelectron spectroscopy. Thin films of Ag/Au-ZnO hybrid nanomaterials were fabricated by doctor blade method and annealing effects on morphology, homogeneity of composition and optical properties promoted the visible-light photocatalytic activity. Samples with bimetallic nanoparticles of higher ablation duration showed better photocatalytic performance. Results of this study show the effectiveness of laser ablation and irradiation in liquid technique as a unique green synthesis for obtention of plasmonic hybrid nanomaterials.

Plasma Discharge across Metal Nanoparticle Surfaces and Plasma-Driven CO2 Reduction to CO and Higher Order Hydrocarbons

: By discharging nanosecond high voltage pulses (up to 25kV) across an insulating substrate coated with metal nanoparticles (Au or Pt), significantly enhanced plasma generation is observed through local field enhancement on the surface of the nanoparticles. The structural integrity of metal nanoparticles can be maintained due to the low-temperature nature of this transient plasma. Electrostatic simulations based on high-resolution transmission electron microscope (HETEM) image of the nanoparticles demonstrate a 3-fold enhancement of the electric field near the nanoparticle surfaces. Since field emission of electrons, which initiates plasma generation, depends exponentially on electric field, this 3-fold increase in the local electric field can significantly enhance plasma generation at a given applied external voltage. Similar enhancement was also observed by discharging in a methane environment, revealing a 50X enhancement in methane upconversion to C2 and higher order hydrocarbons, presenting the exciting possibility of converting a notorious greenhouse gas into an energy dense hydrocarbon fuel. Under laser irradiation, we observe a 200-fold enhancement in the plasma emission intensity, indicating the important role that hot electrons play in the electron emission process. In addition to gas phase plasma discharge, we also demonstrate CO2 reduction to CO and higher order hydrocarbons by discharging nanosecond high votlage pulses in CO2-saturated water, as revealed by C2 Swan band emission, cryogenic NMR spectroscopy and liquid ion chromatography, which indicate clear peaks corresponding to formic acid, methanol, and acetic acid.

Increased Disorder at Graphite Particle Edges Revealed by Multi-length Scale Characterization of Anodes from Fast-Charged Lithium-Ion Cells

Fast charging of lithium-ion cells increases voltage polarization of the electrodes and creates conditions that are favorable for Li-deposition at the graphite anode. Repeated fast charging induces changes in the capacity-voltage profiles and increases the probability of lithium-plating on the electrode. This higher probability results from structural, morphological and chemical modifications that are revealed by multi-length scale characterization of graphite anodes extracted from discharged lithium-ion cells, previously charged at rates up to 6 C. The distinct differences between anodes with lithium-plating and as-prepared electrodes are clearly seen in analytical electron microscopy data. Scanning electrode microscopy (SEM) images show that the fast-charged anode is significantly thicker, apparently because of the electrolyte reduction/hydrolysis products that accumulate in electrode pores. High resolution electron microscopy (HREM) images reveal wavy graphite fringes near the particle edges. Analysis of scanning electron nanodiffraction (SEND) data reveal higher d-spacings and greater lattice rotations, indicating disorder in the graphite near the particle edges that extend about 20 nm into the bulk. The extent of this disorder is greater near larger internal pores, highlighting nanoscale heterogeneities within particles. As graphite lithiation occurs primarily through edge planes, this permanent disorder would hinder Li+ intercalation kinetics and favor Li0 plating during repeated cycling.

Breaking Isolation to Form New Networks: pH-Triggered Changes in Connectivity inside Lipid Nanoparticles.

There is a growing demand to develop smart nanomaterials that are structure-responsive as they have the potential to offer enhanced dose, temporal and spatial control of compounds and chemical processes. The naturally occurring pH gradients found throughout the body make pH an attractive stimulus for guiding the response of a nanocarrier to specific locations or (sub)cellular compartments in the body. Here we have engineered highly sensitive lyotropic liquid crystalline nanoparticles that reversibly respond to changes in pH by altering the connectivity within their structure at physiological temperatures. At pH 7.4, the nanoparticles have an internal structure consisting of discontinuous inverse micellar "aqueous pockets" based on space group Fd3m. When the pH is ≤6, the nanoparticles change from a compartmentalized to an accessible porous internal structure based on a 2D inverse hexagonal phase (plane group p6mm). We validate the internal symmetry of the nanoparticles using small-angle X-ray scattering and cryogenic transmission electron microscopy. The high-resolution electron microscopy images obtained have allowed us for the first time to directly visualize the internal structure of the Fd3m nanoparticles and resolve the two different-sized inverse micelles that make up the structural motif within the Fd3m unit cell, which upon structural analysis reveal excellent agreement with theoretical geometrical models.

Tin sulfide nanoparticles as photocatalysts for the degradation of organic dyes

Tin sulfide (SnS) nanoparticles were prepared from tin(II) dithiocarbamate single source precursors. Powder X-ray diffraction patterns of the SnS nanoparticles confirmed orthorhombic herzenbergite phase of tin sulfide. High-resolution transmission electron microscope images show spherically shaped tin sulfide with particles size in the range 1.0–2.8 nm. The bandgap energy obtained from Tauc plots is in the range 2.95–3.32 eV. The as-prepared SnS nanoparticles were used as nano photocatalysts for the degradation of brilliant green (BG), crystal violet (CV), methylene blue (MB) and methyl red (MR) under visible light irradiation. The degradation efficiency of BG by the SnS nanoparticles after 180 min irradiation are 76%, 81% and 70% by SnS-1, SnS-2 and SnS-3. Degradation efficiency of 66%, 90% and 75% were obtained for SnS-1, SnS-2 and SnS-3, respectively, against CV dye. While the efficiency of 79%, 97% and 93% were obtained for SnS-1, SnS-2 and SnS-3, respectively, against MB dye. The results showed that the as-prepared SnS nanoparticles are efficient photocatalyst for the degradation of BG, CV, MB and MR dyes. Liquid chromatography-mass spectrometry was used to investigate the degradation pathway of the organic dyes. The effects of irradiation time, scavengers and photostability on the photocatalysis process were also evaluated.

Multicolor and white light upconversion luminescence in α-NiMoO4:Yb3+/Ln3+ (Ln = Tm, Ho, Tm/Ho) nanoparticles

In this study, α-NiMoO4:Yb3+ (15 mol%)/Ln3+ (Ln = Tm, Ho, Tm/Ho) phosphors with different doping concentrations of Tm3+ and Ho3+ (0.25, 0.50, 0.75, and 1.00 mol%) were successfully synthesized using a microwave hydrothermal method. Nanorods and attachment of nanoparticles (pebble and sphere) in nanorods were observed in host and doped samples, respectively. According to high-resolution transmittance electron microscopy (HRTEM) images, the interplanar spacings of the samples of 0.22 nm (040), 0.27 nm (−222), 0.35 nm (−112), and 0.61 (110) were well matched with the planes of X-ray diffraction (XRD) patterns. X-ray photoelectron spectroscopy (XPS) and TEM elemental mapping confirmed the incorporation of dopant ions and the uniform distribution of the elements in the samples. By changing the dopant species and concentration, multicolor (blue, green, and red) and white emissions could be achieved in the α-NiMoO4:Yb3+/Ln3+ (Ln = Tm, Ho, Tm/Ho) phosphors under 980 nm laser diode (LD) excitation. The generation of various colors and white light was further confirmed by the CIE color coordinates. The photon process and energy transfer mechanism from Yb3+ to Tm3+ and Ho3+ are also described. Finally, MTT (3-[4,5-dimethylthiazole-2-yl]−2,5-diphenyltetrazolium bromide) assay revealed the non-cytotoxic nature of the samples at low concentrations (below 0.125 mg/mL) in bovine skeletal muscle cells. These findings open the potential application of α-NiMoO4:Yb3+/Ln3+ (Ln = Tm, Ho, Tm/Ho) phosphors for multicolor bio-imaging, color displays, and white light sources.

Quaternary equatorial Atlantic deep-sea ostracodes: evidence for a distinct tropical fauna in the deep sea

AbstractLow-latitude, deep-sea faunas remain poorly understood and described. Here, we systematically describe Quaternary deep-sea ostracodes from the Ocean Drilling Program (ODP) Site 925 (Ceara Rise; 4°12.2'N, 43°29.3′W; 3040 m water depth) in the equatorial Atlantic Ocean. Twenty-six genera and 52 species were examined and illustrated with high-resolution scanning electron microscopy images. Six new species are described herein:Pseudocythere spinae,Hemiparacytheridea zarikiani,Pedicythere canis,Xylocythere denticulata,Paracytherois obtusa, andPoseidonamicus sculptus. The results show that deep-sea ostracodes have a tropical faunal element that is distinctive from higher latitude ostracodes, and that is globally distributed in low latitudes. This tropical faunal component is possibly a Tethyan legacy of a fauna that was widely distributed in tropical and extratropical latitudes in deep waters during greenhouse conditions in the Cretaceous and early Cenozoic. Global cooling thereafter shrank its distribution, limiting it to tropical latitudes, perhaps with the relatively warm uppermost bathyal area acting as the source or refuge of this faunal component. Because similar present-day biogeographic patterns (i.e., presence and wide distribution of tropical deep-sea fauna) are known in other deep-sea benthic groups, this scenario might be applicable to the deep-sea benthos more broadly.UUID:http://zoobank.org/552d4cb2-c0db-463a-ae3f-b2efcc0985df.

Confined Ir single sites with triggered lattice oxygen redox: Toward boosted and sustained water oxidation catalysis

Confined Ir single sites with triggered lattice oxygen redox: Toward boosted and sustained water oxidation catalysis

Anti-coking freeze-dried NiMgAl catalysts for dry and steam reforming of methane

Finding supported nickel catalysts with high activity and stability is yet a challenging aim for industrial applications. In this work, we synthesized a surface defect-promoted Ni catalyst supported on Mg/Al hydrotalcite via a freeze-dried method instead of calcination. This approach leads to the increase in oxygen vacancies, which is attributed to the high dispersion of active sites after adding samarium. X-ray diffraction (XRD) measurements demonstrate a homogeneous layered double hydroxide (LDH) structure without the formation of any oxides. High-resolution transmission electron microscopy (HR-TEM) and field emission scanning electron microscopy images (FE-SEM) illustrated that the samarium-promoted NiMgAl catalyst possesses a scaffold structure with surface defects and oxygen vacancies compared to the unpromoted NiMgAl catalyst which confirmed by X-ray photoelectron spectroscopy (XPS). Moreover, the impact of the samarium incorporation on the physicochemical features of NiMgAl catalysts was investigated for catalytic activity in dry and steam reforming of methane at 700 °C. NiMgAl-Sm catalyst showed the highest conversion of CH4 (72%) and stability without any carbon formation during 20 h of time on stream in dry reforming process. because the strong metal–support interaction inhibits the sintering of nanocatalysts at 700 °C and the scaffold structure increases the mass transportation of feedstock and products.

Bismuth mobile promoter and cobalt-bismuth nanoparticles in carbon nanotube supported Fischer-Tropsch catalysts with enhanced stability

Metal nanoparticles on the surface of porous supports have found numerous applications in different areas of science. Fischer-Tropsch synthesis, which proceeds on the surface of cobalt metal nanoparticles, is an efficient way to convert renewables and fossil feedstocks into alternative fuels. The stability of cobalt catalysts is an essential and even crucial parameter and can be significantly improved by promotion.In this paper, a combination of operando Quick-XAS, NAP-XPS, high resolution electron microscopy imaging, DFT modeling alongside with Fischer-Tropsch catalytic experiments has provided deep insights into the evolution of bismuth promoter and structure of cobalt-bismuth nanoparticles in the catalysts supported by carbon nanotubes. We uncovered noticeable migration of metallic bismuth occurring during the reduction step, which leads to bismuth redispersion over the surface of cobalt nanoparticles. Cobalt reduction is facilitated in the presence of bismuth. The working Fischer-Tropsch catalyst contains cobalt-bismuth bimetallic nanoparticles, with bismuth located in the nanoparticle shell. The promotion with bismuth has resulted in a noticeable increase in catalyst stability. Characterization and DFT modeling suggest preferential localization of bismuth mobile promoter at the steps and edges of cobalt nanoparticles, which hinders cobalt sintering and carbon deposition and improves the catalyst stability.

Irradiation-Driven Restructuring of UO2 Thin Films: Amorphization and Crystallization

Combustion synthesis in uranyl nitrate-acetylacetone-2-methoxyethanol solutions was used to deposit thin UO2 films on aluminum substrates to investigate the irradiation-induced restructuring processes. Thermal analysis revealed that the combustion reactions in these solutions are initiated at ∼160 °C. The heat released during the process and the subsequent brief annealing at 400 °C allow the deposition of polycrystalline films with 5-10 nm UO2 grains. The use of multiple deposition cycles enables tuning of the film thicknesses in the 35-260 nm range. Irradiation with Ar2+ ions (1.7 MeV energy and a fluence of up to 1 × 1017 ions/cm2) is utilized to generate a uniform distribution of atomic displacements within the films. X-ray fluorescence (XRF) and alpha-particle emission spectroscopy showed that the films were stable under irradiation and did not undergo sputtering degradation. X-ray photoelectron spectroscopy (XPS) showed that the stoichiometry and uranium ionic concentrations remain stable during irradiation. The high-resolution electron microscopy imaging and electron diffraction analysis demonstrated that at the early stages of irradiation (below 1 × 1016 ion/cm2) UO2 films show complete amorphization and beam-induced densification (sintering), resulting in a pore-free disordered film. Prolonged irradiation (5 × 1016 ion/cm2) is shown to trigger a crystallization process at the surface of the films that moves toward the UO2/Al interface, converting the entire amorphous material into a highly crystalline film. This work reports on an entirely different radiation-induced restructuring of the nanoscale UO2 compared to the coarse-grained counterpart. The preparation of thin UO2 films deposited on Al substrates fills an area of national need within the stockpile stewardship program of the National Nuclear Security Administration and fundamental research with actinides. The method reported in this work produces pure, robust, and uniform thin-film actinide targets for nuclear science measurements.

Water and oxygen environment induced surface cracks healing in solution processed gallium oxide thin films

Solution based low temperature gallium oxide (Ga2O3) films with high quality is present need for large area deposition, cracks and other parameters resist the use of these films in applications. We have tried to develop good quality crack free films of Ga2O3. Deposition of Ga2O3 thin films by spin coating method and investigation of removal of surface cracks by adding secondary solvent (water) under oxygen environment. The as-synthesized film (without water and oxygen) shows cracks all over the surface. Deionized (DI) water and oxygen atmosphere act as efficient medium that alter surface energy of thin films while undergoing heat treatment. During the heat treatment of the thin films, addition of water forms interparticulate system between the molecules, yielding better evaporation balance and the oxygen environment helps to seize the rate of molecule evaporation which improves the surface uniformity of the thin film. A significant variation in the surface morphology of the films is observed using high-resolution scanning electron microscopy (SEM) and atomic force microscopy (AFM) images. X-ray diffraction (XRD) and Raman spectroscopy are used for the structural confirmation of the thin films. Increase in surface roughness is observed (from 0.28 nm to 0.98 nm) with increase in annealing temperature. Improvement in the crystalline feature results into augmented current density value. The developed crack-free films can be utilized for various electronics and optoelectronics application.

High-Resolution Insights Into the in vitro Developing Blood-Brain Barrier: Novel Morphological Features of Endothelial Nanotube Function.

High-resolution electron microscopy (HREM) imaging of the in vitro blood-brain barrier (BBB), is a promising modality for investigating the dynamic morphological interplay underpinning BBB development. The successful establishment of BBB integrity is grounded in the brain endothelial cells (BEC’s) ability to occlude its paracellular spaces of brain capillaries through the expression of the intercellular tight junction (TJ) proteins. The impermeability of these paracellular spaces are crucial in the regulation of transcellular transport systems to achieve homeostasis of the central nervous system. To-date research describing morphologically, the dynamics by which TJ interaction is orchestrated to successfully construct a specialized barrier remains undescribed. In this study, the application of HREM illuminates the novel, dynamic and highly restrictive BEC paracellular pathway which is founded based on lateral membrane alignment which is the functional imperative for the mechanical juxtapositioning of TJ zones that underpin molecular bonding and sealing of the paracellular space. For the first time, we report on the secretion of a basement membrane in vitro, which allow BECs to orientate themselves into distinct basolateral and apicolateral domains and establish a 3-dimensional BEC construct. We report for the first time, on the expression of nanovesicles bound to the plasma membrane surfaces of the BECs. These membrane-bound vesicles are reported to possess an array of DNA/RNA constituents and chemotaxic properties affecting the formation of nanotubes that span the paracellular space between BECs, facilitating BBB construction, alluding to a functional role in mediating cell-to-cell communication. This study suggests that novel, ultrathin nanotubular (NT) structures are involved in functional roles in bringing into alignment the paracellular space of BECs. Immortalized mouse BECs (b.End3, b.End5) and primary rat cardiac microvascular ECs were used to further validate the in vitro BBB model by profiling variances in peripheral EC monolayer development. These cardiac capillary ECs presented with an opposite topographical profile: large fenestra and intercellular spaces, devoid of morphological ultrastructures. This comparative study alludes to the role of NT facilitation in TJ-induced hemifusion of apicolateral BEC membranes, as a structural event forming the basis for establishing a polarized BBB.

Effect of structural deformations on the transport properties of half-doped manganite nanowires: An insight through high resolution image simulation

Study of structural deformations in manganite nanowires (NWs) are strongly required as in one dimensional (1D) NWs the structural deformations contribute hugely in controlling the electronic properties of the NWs. High resolution image simulation technique has been applied to resolve the atomic structure of a complex layered crystal, (La1−xCaxMnO3; x = 0.3 and 0.5), which comprises a high density of distorted lattice interfaces. This technique allows us to study lattice imperfections, like stacking disorder, twinning and layer undulations, with atomic scale resolution. Aberration corrected High Resolution Electron Microscopy (HREM) images directly reveals the projected crystal structure. Here it is obtained by exploring the strong suppression of image delocalization and using certain spherical-aberration coefficient (Cs) imaging conditions. It has been explained and correlated that the disordered system formation in NWs is due to the defects (termination of sites) in atomic column.

Controlling the performance of one-dimensional homojunction UV detectors based on ZnO nanoneedles array

In this paper, we report on the solution-based synthesis of the n- and p-doped zinc oxide (ZnO) nanoneedle arrays (NNAs) to fabricate p-n homojunction ultraviolet (UV) detectors. Gallium (Ga), copper (Cu), and silver (Ag) were successfully incorporated into the ZnO NNAs lattice by the chemical bath deposition technique. Field emission scanning electron microscope (FESEM) images clearly illustrate the nanoneedles shape for both doped and undoped samples. The growth mechanism of NNAs, together with their structural, morphological, and optical properties, are systematically investigated. Changes of the interplanar spaces in the high-resolution transmission electron microscope (HRTEM) images, peak shifts in the X-ray diffraction (XRD) patterns, and high-resolution X-ray photoelectron spectroscopy (HRXPS) curves all together confirm the successful incorporation of the dopant elements into the ZnO lattice structure. Photocurrent-voltage (I-V) measurements of the one-dimensional p-n homojunction reveal a rectifying diode behavior. Incorporating the Ga donor into the ZnO NNAs decreases the threshold voltage by three times. I-V curves show that the diode with Ag acceptor and Ga donor has the lowest threshold voltage of 0.2 V. These results also manifest that the introduction of Ga donor reduces the rectifying ratio (RR) by five times compared to undoped-ZnO in the diode n-side. The maximum RR of 12.7 is recorded at ±1.5 V for the diode composed of undoped and Cu-doped ZnO. Furthermore, the same diode depicts the UV light highest sensitivity with more than 50 % current enhancement under the UV illumination.

A Singular Molecule-to-Molecule Transformation on Video: The Bottom-Up Synthesis of Fullerene C60 from Truxene Derivative C60H30.

Singular reaction events of small molecules and their dynamics remain a hardly understood territory in chemical sciences since spectroscopy relies on ensemble-averaged data, and microscopic scanning probe techniques show snapshots of frozen scenes. Herein, we report on continuous high-resolution transmission electron microscopic video imaging of the electron-beam-induced bottom-up synthesis of fullerene C60 through cyclodehydrogenation of tailor-made truxene derivative 1 (C60H30), which was deposited on graphene as substrate. During the reaction, C60H30 transformed in a multistep process to fullerene C60. Hereby, the precursor, metastable intermediates, and the product were identified by correlations with electron dose-corrected molecular simulations and single-molecule statistical analysis, which were substantiated with extensive density functional theory calculations. Our observations revealed that the initial cyclodehydrogenation pathway leads to thermodynamically favored intermediates through seemingly classical organic reaction mechanisms. However, dynamic interactions of the intermediates with the substrate render graphene as a non-innocent participant in the dehydrogenation process, which leads to a deviation from the classical reaction pathway. Our precise visual comprehension of the dynamic transformation implies that the outcome of electron-beam-initiated reactions can be controlled with careful molecular precursor design, which is important for the development and design of materials by electron beam lithography.

Conductive In Situ Reduced Graphene Oxide-Silk Fibroin Bionanocomposites.

This research paper describes the fabrication of bionanocomposites (BNCs) based on silk fibroin (SF) and reduced graphene oxide (rGO). The recorded UV–visible (UV–vis) spectra of the sample confirm the reduction of GO to rGO in SF by showing a plasmon resonance band within the wavelength range of 261–268 nm. The X-ray diffraction (XRD) peak at 11.6° corresponding to the GO intensity decreases with increasing reaction time, resulting in rGO in the SF host matrix. The morphological behavior of the SF–rGO BNCs is scrutinized using scanning electron microscopy (SEM), and the images clearly indicate the existence of rGO within the matrix. The increasing amount of GO in the SF shows broken graphene sheets, which can increase the surface roughness and establish a strong physical contact between the SF and rGO nanosheets. The high-resolution transmission electron microscope (HR-TEM) image of the bionanocomposite showed that the formed rGO encompassments of fewer layers are stacked, each with fewer wrinkles and folding. The Raman spectroscopy confirmed the formation of rGO by showing the increased intensity ratio of D to G band (ID/IG) in the bionanocomposite samples. The rGO effect on the electrical conductivity is measured, and the results show that DC conductivity increases from 1.28 × 10–9 to 82.4 × 10–9 S/cm with an increase in the GO content in the SF biopolymer. The investigations demonstrate loss of the insulation property and improved conducting behavior of the SF biopolymer.

Minimizing Convolutional Neural Network Training Data With Proper Data Augmentation for Inline Defect Classification

Detecting the defects of the semiconductor devices produced using manufacturing processes is essential for quality assurance, and it requires the acquisition and accurate classification of high-resolution scanning electron microscopy images. However, owing to the difficulty of automation, the classification process is costly, and its efficiency must also be improved. To improve the classification accuracy and reduce the cost of classifiers, which are the main bottlenecks of conventional technology, we proposed a deep convolutional neural network (CNN) based on the VGG16 architecture and performed appropriate data augmentations on training images. Reducing training images is an effective method for reducing the cost of creating classifiers. However, in this case, the classification accuracy is insufficient, as it greatly varies depending on the number of training images. The appropriate data augmentation of training images is an effective method for solving this problem. It was important to note that improper data augmentation reduces the classification accuracy. Also, we managed to find the optimal data augmentation type for a possible defect type.