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Based on our preceding discussions of atomic-resolution characterization techniques in Chapter 4, no technique has yet achieved ASAT. Combining information from FIM or (S)TEM along with APT has demonstrated some very promising results, and each combination seems to be a likely path toward ASAT. In this chapter, we propose how ASAT might be achieved using correlative and/or combined techniques such as (S)TEM + APT. Such a combination would allow several routes for determination of the ion transfer function, or how imaging occurs during an APT experiment. If we can determine the transfer function with high-enough fidelity, we make the argument that it should be possible to achieve ASAT using a combination of (S)TEM and APT with inputs from simulations.
A comprehensive guide on Atomic-Scale Analytical Tomography (ASAT) that discusses basic concepts and implications of the technique in areas such as material sciences, microscopy, engineering sciences and several interdisciplinary avenues. The title interrogates how to successfully achieve ASAT at the intersection of transmission electron microscopy and atom probe microscopy. This novel concept is capable of identifying individual atoms in large volumes as well as in 3D, with high spatial resolution. Written by leading experts from academia and industry, this book serves as a guide with real-world applications on cutting-edge research problems. An essential reading for researchers, engineers and practitioners interested in nanoscale characterisation, this book introduces the reader to a new direction for atomic-scale microscopy.
The crystal structures of 11 lanthanide terephthalate tetrahydrates have been refined using laboratory X-ray powder diffraction data and optimized using density functional techniques. The lattice parameters and R–O bonds exhibit expected trends based on the cation size. The R–O bond distances in the Rietveld-refined structures are similar. However, in the density functional theory (DFT)-optimized structures, the bond distances break into two distinct groups, longer and shorter R–O bonds. This indicates that the bond distance restraints imposed upon the refined structures may have a greater impact than is expected from their weights. The aromatic carboxyl groups were not completely planar, but it is known that the carboxyl groups can rotate to accommodate hydrogen bonding and coordination to the metal. Both water molecules coordinated to the lanthanides act as hydrogen bond donors, but only one of the three unique carboxyl groups acts as an acceptor.
Preterm infants show postnatal deficits of long-chain polyunsaturated fatty acids (LCPUFAs) which are essential for adequate growth and neurodevelopment. Human milk is a primary source of fatty acids (FAs) for the preterm infant, and therefore, knowledge about milk FA levels is required to design appropriate supplementation strategies. Here, we expanded on our previous study (Nilsson et al., 2018, Acta Paediatrica, 107, 1020–1027) determining FA composition in milk obtained from mothers of extremely low gestational age (<28 weeks) infants on three occasions during lactation. There was a clear difference in FA composition in milk collected at Day 7 and milk collected at postmenstrual weeks (PMW) 32 or PMW 40. Notably, the proportion of LCPUFAs was low and declined significantly during milk maturation. These results strengthen previous data that the content of FAs required by the preterm infant is not supplied in sufficient amounts when the mother’s own milk is the sole source of these essential nutrients.
Atmospheric simulation data present richer information in terms of spatiotemporal resolution, spatial dimension, and the number of physical quantities compared to observational data; however, such simulations do not perfectly correspond to the real atmospheric conditions. Additionally, extensive simulation data aids machine learning-based image classification in atmospheric science. In this study, we applied a machine learning model for tropical cyclone detection, which was trained using both simulation and satellite observation data. Consequently, the classification performance was significantly lower than that obtained with the application of simulation data. Owing to the large gap between the simulation and observation data, the classification model could not be practically trained only on the simulation data. Thus, the representation capability of the simulation data must be analyzed and integrated into the observation data for application in real problems.
Asteroid and cometary impacts have been considered one of the possible routes for exogenous delivery of organics to the early Earth. It is well established that amino acids can be synthesized due to impact-driven shock processesing of simple molecules and that amino acids can survive the extreme conditions of impact events. In the present study, we simulate impact-induced shock conditions utilizing a shock tube that can maintain a reflected shock temperature of about 5,500 K for 2 ms time scale. We have performed shock processing of various combinations of amino acids with subsequent morphological analysis carried out using Scanning Electron Microscope (SEM), revealing that the shock processed amino acids demonstrate an extensive range of complex structures. These results provide evidence for the further evolution of amino acids in impact-induced shock environments leading to the formation of complex structures and thus providing a pathway for the origin of life.
This article presents cyclic hardening/softening behaviors (experimental data) of the heat-treated aluminum-matrix nano-clay-composite (AlSi_N_HT6), compared to those of the piston aluminum alloy (AlSi) under strain-controlled loading. For such an objective, standard samples were fabricated by gravity and stir-casting methods. Low-cycle fatigue experiments were carried out under different strain amplitudes (0.20–0.45%) and at various temperatures (25–300°C). Obtained results implied that no obvious change was observed on material properties of aluminum alloy by reinforcements, but a decrement was observed due to increasing the temperature. Results also indicated that the increase of the temperature from 25°C to 200°C has changed the cyclic behavior of both materials (AlSi_N_HT6 and AlSi) from hardening to softening. Moreover, the temperature effect was more significant than the total strain amplitude influences in cyclic behaviors.
Environmental benign and stable kesterite Cu2ZnSnS4 (CZTS) photovoltaics provides an intriguing alternative to conventional solar cells. However, further development is required for boosting the Voc-deficit in CZTS photovoltaic to enhance the cell function. Intending to obtain high-quality CZTS powder as the basis, here we report a comprehensive study of the vacuum annealing process (including annealing temperature, duration, and heating rates) for synthesized powder with the ball-milling method, which leads to a high-quality kesterite structure. According to analysis outcomes, there are not any significant differences in structures of differently milled specimens while the optical and morphological findings exhibit distinctive results. In short, the 10 h milled powder annealed at 500 °C for 5 h with a 9 °C min−1 heating rate possesses a high-quality structure alongside the desired 1.53 eV bandgap and optimum morphological characteristics.
This study quantified CO2 emissions from tropical peat swamp soils in Brunei Darussalam. At each site, soil was collected from areas of intact and degraded peat and CO2 flux, and total organic content were measured ex situ. Soil organic content (~20–99%) was not significantly different between intact and degraded forest samples. CO2 flux was higher for intact forest samples than degraded forest samples (~1.0 vs. ~0.6 μmol CO2 m−2 s−1, respectively) but did not differ among forest locations. From our laboratory experiments, we estimated a potential emissions of ~10–20 t CO2 ha−1 y−1 which is in the lower range of values reported for other tropical peat swamps. However, our results are likely affected by unmeasured variation in root respiration and the lability of resident carbon. Overall, these findings provide experimental evidence to support that clearance of tropical peat swamp forests can increase CO2 emissions due to faster rates of decomposition.
Land equivalent ratio (LER) is a most widely used indicator of yield advantage of multi-crop farms over sole-crop farms, and usually measured using crop biomass yield per unit area. Most often, crop yields are compared between both systems using the same area. In this paper, we demonstrate that although the yield per unit area and the yield per plant are widely different, LER remains invariant. As a corollary, area time equivalent ratio and land use efficiency, derived from LER, also remain unchanged when using the two different measures of crop yields. We recommend that when the estimation of the exact land area is difficult due to complex crop planting designs, yield per plant estimate is much easier and equally valid for estimation of LER and its derivative indices.
The phenomenon of antimicrobial resistance represents a major public health risk. The activity of integral membrane transporter proteins contributes to antimicrobial resistance in pathogenic bacteria and proton gradient-driven multidrug efflux representatives of the major facilitator superfamily (MFS) of secondary transporters are the dominant antimicrobial efflux proteins in Escherichia coli. In many, but not all, of the characterized MFS multidrug transporters, an aspartic acid residue at position D+5 of the conserved signature Motif A is essential for transport activity. The present work extends those studies to the E. coli MFS multidrug/H+ antiporter MdtM and used a combination of mutagenesis, expression studies, antimicrobial resistance assays, and transport activity measurements to reveal that a negatively charged residue at position D+5 is critical for MdtM transport function.
Quantitative phase analysis is one of the major applications of X-ray powder diffraction. The essential principle of quantitative phase analysis is that the diffraction intensity of a component phase in a mixture is proportional to its abundance. Nevertheless, the diffraction intensities of the component phases cannot be compared with each other directly since the coherent scattering power per unit cell (or chemical formula) of each component phase is usually different. The coherent scattering power per unit cell of a crystal is well represented by the sum of the squared structure factors, which cannot be calculated directly when the crystal structure data is unavailable. Presented here is a way to approximate the coherent scattering power per unit cell based solely on the unit cell parameters and the chemical contents. This approximation is useful when the atomic coordinates for one or more of the phases in a sample are unavailable. An assessment of the accuracy of the approximation is presented. This assessment indicates that the approximation will likely be within 10% when X-ray powder diffraction data is collected over a sufficient portion of the measurable pattern.
Metamaterials, including their two-dimensional counterparts, are composed of subwavelength-scale artificial particles. These materials have novel electromagnetic properties, and can be artificially tailored for various applications. Based on metamaterials and metasurfaces, many abnormal physical phenomena have been realized, such as negative refraction, invisible cloaking, abnormal reflection and focusing, and many new functions and devices have been developed. The effective medium theory lays the foundation for design and application of metamaterials and metasurfaces, connecting metamaterials with real world applications. In this Element, the authors combine these essential ingredients, and aim to make this Element an access point to this field. To this end, they review classical theories for dielectric functions, effective medium theory, and effective parameter extraction of metamaterials, also introducing front edge technologies like metasurfaces with theories, methods, and potential applications. Energy densities are also included.
This Element introduces the exotic wave phenomena arising from the extremely small optical refractive index, and sheds light on the underlying mechanisms, with a primary focus on the basic concepts and fundamental wave physics. The authors reveal the exciting applications of ENZ metamaterials, which have profound impacts over a wide range of fields of science and technology. The sections are organized as follows: in Section 2, the authors demonstrate the extraordinary wave properties in ENZ metamaterials, analyzing the unique wave dynamics and the resulting effects. Section 3 is dedicated to introducing various realization methods of the ENZ metamaterials with periodic and non-periodic styles. The applications of ENZ metamaterials are discussed in Sections 4 and 5, from the perspectives of microwave engineering, optics, and quantum physics. The authors close in Section 6 by presenting an outlook on the development of ENZ metamaterials and discussing the key challenges addressed in future works.